The Pregnant Cardiac Patient

Table I.

Low risk (mortality < 1%)	-Repaired lesions without residual cardiac dysfunction-Uncomplicated left-to-right shunts-Mild pulmonic/tricuspid valvular abnormalities-Bioprosthetic valve-Corrected tetralogy of Fallot-Mitral valve prolapse-Bicuspid aortic valve without stenosis-Regurgitant valves with normal systolic function
Intermediate risk (mortality 1 – 5%)	-Metal valves-Large left-to-right shunt-Uncorrected coarctation of the aorta-Single ventricles-Systemic right ventricle; switch procedure-Unrepaired tetrology of Fallot or other unrepaired congenital cyanotic lesions-Mitral stenosis-Aortic stenosis-Severe pulmonic stenosis-Previous myocardial infarction-Moderate ventricular dysfunction-History of peripartum cardiomyopathy without residual dysfunction
High risk (mortality 5 – 30%)	-NYHA Class III or IV-Severe systemic ventricular dysfunction-Severe aortic stenosis-Marfan’s syndrome with aortic valve lesion or aortic dilatation-Pulmonary hypertension-History of peripartum cardiomyopathy with residual dysfunction

A prospective trial of pregnancy outcomes in women with heart disease identified four predictors associated with cardiac events: prior cardiac event, baseline NYHA class > II or cyanosis, left heart obstruction, and reduced systemic ventricular systolic function. The predictors of cardiac events were incorporated into a risk index in which one point was assigned for each risk factor. The estimated risk of a cardiac event in pregnancies with 0, 1, and >1 points was 5%, 27%, and 75%, respectively.

3. What are the implications of co-existing disease on perioperative care?

The spectrum of disease in pregnant cardiac patients is broad, and the implications will vary depending upon the pathophysiology and the clinical scenario.

Antepartum care

The pregnant cardiac patient should be followed carefully by providers comfortable with both cardiovascular physiology and pregnancy. The patient should be regularly questioned and evaluated for increasing fatigue, dyspnea, palpitations, and edema. Although these symptoms may be normal in pregnancy, if changes are reported, further evaluation for failure, cyanosis, end-organ dysfunction, or other complications of pregnancy (e.g. preeclampsia or preterm labor) is warranted.

Pregnant patients with a significant cardiac history will be followed with serial transthoracic echocardiography exams to evaluate function and guide care. A common screening regimen is to obtain a transthoracic echocardiography exam in each trimester, and as needed, to evaluate the patient following a clinical change. Other studies (e.g. Holter monitoring or a 12-lead electrocardiogram) may be obtained as indicated.

Peripartum risk reduction strategies

The pregnant cardiac patient will require careful evaluation upon admission to labor and delivery. A thorough history and physical exam and review of the most recent diagnostic studies should be performed. The management should be tailored for each individual patient, but some basic principles will apply. With rare exception, vaginal delivery with an assisted second stage is preferred, and cesarean delivery is reserved for obstetric indications.

Low-dose epidural analgesia is recommended for women with who are not on therapeutic anticoagulation. The combination of good pain control, limited sympathetic stimulation, and an assisted second stage limits myocardial oxygen consumption and hemodynamic lability. Invasive monitoring (e.g., arterial-line), telemetry, or delivery in an intensive-care unit may also be necessary to optimize the care of these complex patients.

b. Cardiovascular system

Atrial septal defect (ASD)

This is the most common congenital lesion in pregnancy. Approximately 20-30% of patients with an ASD will have mitral valve prolapse. Complications associated with an ASD include arrhythmias and pulmonary hypertension.

Ventricular septal defect (VSD)

This is infrequently diagnosed in pregnancy. Most VSDs either close spontaneously or are surgically corrected in childhood. Membranous VSDs may be associated with aortic regurgitation, and complications associated with a VSD include pulmonary hypertension and right ventricular failure.

Left-to-right shunts

Repaired defects (ASD, VSD, and patent ductus arteriosus) do not require any special treatment. Small left-to-right shunts are generally well-tolerated in pregnancy; however, a large defect with chronic shunting results in volume expansion that will be further increased with pregnancy. Chronic left-to-right shunts may lead to pulmonary hypertension, reversal of the shunt, and cyanosis. Echocardiography is recommended in pregnancy to evaluate cardiac function and detect pulmonary hypertension.

During labor and delivery, the left-to-right shunt may be transiently reversed following a Valsalva maneuver or with a sudden drop in systemic blood pressure, as may occur with regional anesthesia or a postpartum hemorrhage. In addition, pain-associated sympathetic stimulation can increase systemic vascular resistance (SVR), worsen the left-to-right shunting, and result in right ventricular failure. Goals during labor and delivery include limiting sympathetic stimulation, maintaining SVR to avoid reversal of the shunt, removal of air from intravenous lines and injections, and use of supplemental oxygen, if needed, to prevent hypoxia.

Eisenmenger's syndrome

This is the highest risk condition for the parturient. Chronic left-to-right shunting increases pulmonary blood flow, and over time this will induce vascular remodeling and pulmonary hypertension. When the pressures on the right side are greater than the left, reversal of the shunt and cyanosis will occur. Once Eisenmenger’s pathophysiology has been established, pulmonary hypertension is permanent. Maternal mortality in patients with Eisenmenger’s syndrome is estimated to be between 30-40%, and termination of the pregnancy is encouraged.

The physiologic changes of pregnancy are poorly tolerated in this population: the right ventricle is at risk for failure, as cardiac output increases and the normal pregnancy-related decrease in pulmonary vascular resistance (PVR) does not occur because PVR in these patients is fixed. Consequently, the physiologic decrease in SVR increases the shunt and worsens the cyanosis. During labor and delivery, the right-to-left shunt may be further increased from sympathetic stimulation, pain, hypercarbia, hypoxia, and/or acidosis.

Thus, the goal is to maintain SVR and intravascular volume, control pain and the sympathetic response to labor, and limit hypoxia. Supplemental oxygen and pulmonary artery vasodilators (e.g. inhaled nitric oxide or prostacyclin) may be helpful in management. Postpartum hemorrhage should be aggressively treated, keeping in mind that these patients will not tolerate volume overload. Lastly, thromboembolic events are a substantial cause of mortality in this patient population, and peripartum anticoagulation is common.

Tetralogy of Fallot

This is the most common form of cyanotic congenital heart disease, and involves four components: a large VSD, right ventricular outflow tract obstruction, overriding aorta, and right ventricular hypertrophy. Most patients reaching reproductive age will have had surgical correction, although some residual defects may be present. Surgical palliation, usually performed for symptomatic neonates and infants, involves a systemic to pulmonary shunt, like the Blalock shunt. Surgical correction is done in stable patients sometime between 6 months and 2 years of age, and involves closure of the VSD and relief of the right ventricular outflow tract obstruction.

Following repair, patients may have pulmonic valvular regurgitation, aortic valvular regurgitation, ventricular or atrial arrhythmias, right ventricular dilatation, or a residual VSD. Pregnancy may unmask residual defects or complications. Throughout pregnancy, patients should be closely followed with serial echocardiography exams and any associated complications should be aggressively treated.

Management during labor and delivery involves epidural anesthesia for good pain control and an assisted second stage. Arrhythmias are common, and telemetry may be useful. If patients have uncorrected physiology or significant residual defects, management should be tailored to prevent or minimize right-to-left shunting. A recent review of pregnancy outcomes for patients with repaired tetralogy of Fallot found outcomes were generally favorable, although management of congestive heart failure was necessary in 19% of deliveries.

Single ventricle and Fontan circulation

The Fontan procedure is used to treat congenital heart disease in which there is an anatomic or functional single ventricle. The procedure separates the pulmonary and systemic circulations by creating a direct connection between the right atrium or vena cava and the pulmonary artery. Consequently, flow through the pulmonary vasculature is driven by the pressure of the systemic venous return, which makes patients with Fontan circulation particularly susceptible to decreases in systemic venous return.

Long term complications in this patient population include impaired ventricular function, venous congestion, atrial arrhythmias, and thromboembolic events. During labor and delivery, care should be taken to avoid dehydration, hemorrhage, and aortocaval compression, which would decrease central venous pressure and blood flow through the lungs.

Coarctation of the aorta

This is a congenital narrowing of the descending aorta. More than 80% of patients with coarctation are diagnosed and repaired in childhood. Patients with a successful correction require no special monitoring or management during pregnancy. Patients with a gradient of > 20 mmHg between the upper and lower extremities, or unrepaired coarctation, are at risk for left ventricular failure, aortic rupture, and dissection. To minimize hemodynamic fluctuations, these patients may be offered a cesarean delivery. In patients with gradients < 20 mmHg, vaginal delivery with an epidural is preferred.

Marfan's syndrome

This is an autosomal dominant condition of disordered fibrillin synthesis. Cardiovascular manifestations include mitral valve prolapse and regurgitation, aortic valve regurgitation, and ascending aortic dilation and dissection. Patients with minimal disease tolerate pregnancy well. However, patients with a dilated aortic root (> 4 cm in diameter), aortic regurgitation, and left ventricular dysfunction or dilation are at risk for significant morbidity and mortality.

During pregnancy, patients with Marfan’s syndrome should have monthly transthoracic echocardiograms to measure aortic root diameter, and hypertension should be aggressively treated with beta-blockers. Dissection and rupture are most likely to occur in the third trimester or in the peripartum period. Patients with an aortic root diameter < 4 cm and no other significant cardiovascular manifestations may deliver vaginally with an assisted second stage. Patients with a dilated aortic root typically undergo an elective cesarean delivery to minimize hemodynamic instability, which could precipitate aortic dissection. As such, general anesthesia is usually avoided.

Aortic dissection

This occurs in pregnancy in association with preeclampsia, coarctation, congenital bicuspid aortic valve, or connective tissue disorders, like Marfan’s syndrome or Ehler’s-Danlos syndrome. It is most likely to occur in the third trimester or in the early postpartum period. The diagnosis of dissection is made with transesophageal echo, computed tomography, or magnetic resonance imaging.

Initial treatment involves aggressive blood pressure control, beta-blockers for reduction of shear stress with ventricular ejection, and pain control. Patients should have invasive blood pressure monitoring, and central venous access may be helpful. If operative repair is required, the decision regarding concurrent delivery is based upon fetal age and evidence of fetal compromise.

Aortic stenosis (AS)

The most common cause of AS in reproductive-aged women is a congenital bicuspid valve. Asymptomatic patients with mild to moderate disease usually tolerate pregnancy well. In contrast, patients with severe or symptomatic AS have a fixed stroke volume, and will have difficulty accommodating the increased cardiac output required in pregnancy. In severe, symptomatic pregnant patients, balloon valvuloplasty can be considered to relieve symptoms and minimize fetal complications.

Goals for labor and delivery include maintenance of SVR and intravascular volume, maintenance of sinus rhythm and a normal rate, and avoidance of aortocaval compression. If postpartum hemorrhage occurs, it should be aggressively treated to avoid hemodynamic collapse.

Mitral stenosis (MS)

This most often occurs as a result of rheumatic heart disease, and is the most common acquired valvular lesion in pregnancy. The expanded blood volume of pregnancy and increased heart rate in the setting of a significantly narrowed mitral valve lead to increased left atrial pressure, arrhythmias, and pulmonary edema. Medical management of patients with MS involves beta-blockade for control of heart rate and diuretics.

Symptomatic parturients who do not have adequate relief from medical management may benefit from valvuloplasty. Anti-coagulation should be considered in patients with severe left atrial enlargement, even in the absence of atrial fibrillation. As with aortic stenosis, vaginal delivery with an assisted second stage is preferred.

During labor and delivery, goals include maintenance of SVR and intravascular volume, prevention of hypercarbia, hypoxia, and acidosis, maintenance of sinus rhythm and a normal rate, and avoidance of aortocaval compression. After delivery, the increased preload may further compromise these patients, and careful monitoring is recommended for the postpartum period.

Aortic regurgitation (AR) and mitral regurgitation (MR)

Regurgitant lesions are relatively well-tolerated in pregnancy. The hemodynamic changes of pregnancy – decreased SVR, increased circulating volume, and increased heart rate – promote forward flow through the regurgitation valve. Patients who do become symptomatic may be treated medically with diuretics and vasodilators.

Prior prosthetic valve surgery

Patients with a history of prosthetic valve surgery are at increased risk for thromboembolic events, endocarditis, and valve failure. Patients with mechanical valves require chronic anticoagulation, and there are no clear guidelines for managing anticoagulation in pregnancy. In the antepartum period, patients are maintained on warfarin, unfractionated heparin, or low-molecular-weight heparin (LMWH), but may be switched to unfractionated heparin at or near term.

Some patients may require ongoing anticoagulation during labor and delivery, but for others, anticoagulation is typically held at the onset of labor and reinstituted following delivery. Neuraxial anesthesia should not be performed until 24 hours after the last therapeutic dose of LMWH, or until coagulation studies (e.g., PTT in patients on unfractionated heparin) have normalized.

Acute myocardial infarction (acute MI)

This is a rare event in women of reproductive age. Pregnancy increases the risk of an acute MI 3- to 6-fold over non-pregnant age-matched women. The increased cardiac output, myocardial oxygen demand, hypercoagulable state, medications administered during the peripartum period, and co-morbidities, like preeclampsia and postpartum hemorrhage, contribute to ischemic events.

The causes of MI in this patient population are different from that of the general population, with a much great proportion of patients having ischemia due to coronary dissection. Treatment is relatively unchanged in the pregnant population. Medical management, cardiac catheterization, and interventional procedures are viable treatments. Thrombolytic therapy should be used with caution because of limited experience and reports of placental abruption and fetal hemorrhage following administration. A vaginal delivery with an assisted second stage and epidural is preferred.

Peripartum cardiomyopathy

This is a rare form of heart failure manifesting in the last month of pregnancy or within the first five months postpartum. To make the diagnosis, the patient can have no prior history of heart failure and all other possible causes must be excluded. If the patient is pregnant, delivery is indicated, and a vaginal delivery with an assisted second stage is preferred. Medical management is largely supportive: diuretics, inotropic support, and vasodilators. Anticoagulation is also recommended, as these patients are at increased risk of thromboembolic complications.

Hypertrophic cardiomyopathy (HOCM)

This is an inherited cardiomyopathy characterized by intraventricular septal hypertrophy, decreased left ventricular chamber size, and left ventricular dysfunction. The ventricular changes predispose the patient to developing outflow obstruction with tachycardia and decreases in systemic vascular resistance. Many patients with HOCM tolerate pregnancy, although the presence of preconceptual symptoms closely correlates with poor pregnancy outcomes.

Medical management includes beta-blockers and aggressive treatment of arrhythmias, including placement of an implantable cardiac defibrillator, if indicated. During labor and delivery, the goal should be to control pain, maintain intravascular volume and SVR, control the heart rate, maintain sinus rhythm, prevent increases in myocardial contractility, and aggressively treat postpartum hemorrhage.

Pulmonary hypertension

Pulmonary hypertension is defined as a systolic pulmonary artery pressure (PAP) of > 35 mmHg, or a mean PAP > 25 mmHg. This condition is classified as either primary or secondary. Primary pulmonary hypertension is a rare disease which primarily affects young women of reproductive age. It is characterized by an imbalance in vascular mediators, which results in medial thickening and intimal fibrosis. Patients with pulmonary hypertension are at risk for ventricular failure when pregnancy-induced increases of blood volume and cardiac output are superimposed on a poorly-compliant vasculature.

The maternal mortality rate may be as high as 30%, and most deaths occur between 2 and 9 days postpartum. Medical management of the pregnant patient includes supplemental oxygen, inhaled nitric oxide, inhaled, subcutaneous, or intravenous (IV) prostacyclin, and sildenafil. Throughout pregnancy and delivery, hemodynamic goals should be to prevent pain, hypoxemia, acidosis, and hypercarbia, maintain SVR above right-sided pressures to ensure coronary perfusion of the right ventricle, maintain intravascular volume while avoiding volume overload, and avoid tachyarrhythmias.

c. Pulmonary

Reactive airway disease (asthma) is a common condition affecting many parturients, including those with cardiovascular disease. An asthma exacerbation may increase pulmonary artery pressures, and patients with preexisting pulmonary hypertension (primary or secondary), intracardiac shunts, or ventricular failure may clinically deteriorate. Attempts should be made to decrease the frequency and severity of asthma exacerbations. Those that occur should be aggressively treated to prevent additional complications.

d. Renal-GI:

Gastric emptying is reduced in labor. In addition, the physiologic changes associated with pregnancy (e.g. decreased lower esophageal sphincter tone and mechanical compression of the stomach) predispose this patient population to aspiration during induction of general anesthesia or manipulation of the airway. As such, laboring patients are typically induced using a rapid sequence technique. In the pregnant cardiac patient, however, the risks of a rapid induction with the potential for hemodynamic instability must be weighed against the risk of aspiration and individualized to the patient and clinical scenario.

e. Neurologic:

Some patients with underlying cardiovascular disorders (e.g. arrhythmias, dilated cardiomyopathy, mitral stenosis, and intracardiac shunts) are at risk for strokes or transient ischemic attacks (TIA). In a prospective trial of pregnancy outcomes in women with heart disease, one of the risk factors associated with cardiac complications was stroke or TIA preceding pregnancy. Thus, neurologic comorbidities imply severe disease and help predict which patients are at increased risk of poor outcomes.

f. Endocrine:

N/A

g. Additional systems/conditions which may be of concern in a patient undergoing this procedure and are relevant for the anesthetic plan (eg. musculoskeletal in orthopedic procedures, hematologic in a cancer patient)

Preeclampsia and eclampsia are a part of a spectrum of hypertensive disorders specific to pregnancy. The maternal manifestations are consistent with a process of vasospasm, local ischemia, and changes in the normal balance of autocoid and humoral mediators. Clinical signs and symptoms include hypertension, proteinuria, neurologic signs and symptoms, pulmonary edema, liver dysfunction, thrombocytopenia, and oliguria.

The treatment is administration of magnesium sulfate for seizure prophylaxis and delivery. Overall, patients with cardiovascular disease are at not at significantly greater risk of developing preeclampsia than the general population; however, some of the risk factors for preeclampsia, like preexisting hypertension, diabetes, advanced maternal age, and multiple gestations, overlap with risk factors for ischemic heart disease and peripartum cardiomyopathy. If preeclampsia does develop in this patient population, the disease itself and the treatments for it can further complicate care of these challenging patients.

4. What are the patient's medications and how should they be managed in the perioperative period?

In contrast to the typical pregnant woman who will be on few, if any, chronic medications, the pregnant cardiac patient may need multiple agents to optimize her cardiovascular status. Common medications in this patient population include beta-blockers, diuretics, aspirin, anti-hypertensives, and anticoagulants.

h. Are there medications commonly seen in patients undergoing this procedure and for which should there be greater concern?

Below are some of the most common medications administered during labor and delivery, with emphasis on their cardiovascular effects.

Uterotonics are agents which stimulate uterine contractions. Oxytocin is a synthetic hormone commonly administered intravenously (IV) during labor and delivery. It is given as an infusion for initiation or augmentation of contractions during labor. It is also indicated for use in higher doses to improve uterine tone following the second stage of labor, or in response to postpartum hemorrhage from atony.

Intravenous bolus doses are contraindicated, as they will lead to acute drops in afterload and the need for increased cardiac output to maintain blood pressure. Side effects include tachycardia, hypotension, hypertension, arrhythmias, and hyponatremia. Although the lower doses used for induction of labor are generally well-tolerated, in the setting of postpartum hemorrhage and high dose administration, alternatives should be considered in patients with significant lesions and a tenuous state.

Prostaglandins are widely used for cervical ripening and induction of labor and for the treatment of postpartum hemorrhage. When placed vaginally and used in low doses for cervical ripening, prostaglandins are generally well-tolerated with few systemic side effects. Two agents, misoprostol and carboprost, are used to treat uterine atony. Misoprostol (Cytotec®) may be given vaginally, rectally, or intra-uterine, and the most common side effect is pyrexia. Cardiac dysrhythmias and myocardial infarction have been reported but are very rare.

Carboprost (Hemabate®) is administered intramuscularly, and has a number of well known side effects including nausea, vomiting, diarrhea, bronchospasm, and hypertension. Pulmonary edema and increased pulmonary vascular resistance have been reported, but are rare.

Methergine® is an ergot alkaloid given for treatment of atony and postpartum hemorrhage. Intramuscular (IM) administration is recommended because IV injection has been associated with severe hypertension, stroke, coronary vasospasm, myocardial infarction, pulmonary hypertension, and pulmonary edema. Side effects may still occur with IM injection, and caution or avoidance of the drug is recommended in patients with underlying hypertension, pulmonary hypertension, peripheral vascular disease, preeclampsia, or coronary artery disease.

Tocolytics are used to delay or stop premature labor in patients with viable fetuses less than or equal to 34 weeks gestation, with no maternal or fetal indications for delivery. Beta-adrenergic agonists (e.g. terbutaline) are commonly used to delay premature labor in patients. These agents act via a second-messenger system to inhibit myometrial contractions and relax smooth muscle.

They affect other organ systems with beta-adrenergic receptors, and can produce bronchodilation, vasodilatation, tachycardia, hyperglycemia, hypokalemia and metabolic acidosis. Pulmonary edema and chest pain may develop, but are rare in the setting of less than 24 hours of therapy. Many patients with preexisting cardiac disease will not tolerate the tachycardia and hypotension commonly associated with these drugs, and alternative therapies should be considered.

Magnesium sulfate is used for the prevention of preeclamptic seizures and as a tocolytic agent. Magnesium sulfate antagonizes intracellular calcium and inhibits myometrial contraction. Side effects of magnesium sulfate treatment include hyporeflexia, weakness, lethargy, hypotension, and nausea. At higher concentrations, ECG changes and pulmonary edema are possible.

Calcium channel blockers (e.g., nifedipine) directly block the influx of calcium through the cell membrane and the subsequent release of calcium from the sarcoplasmic reticulum, thus inhibiting uterine contractions. Calcium channel blockers are effective tocolytics, but side effects include hypotension and reflexive tachycardia. Cyclooxygenase inhibitors, like indomethacin, inhibit arachidonic acid conversion to prostaglandins, which are necessary for parturition. Maternal side effects are uncommon.

Vasopressors are another common class of medication used during labor and delivery. Regional anesthesia produces a sympathetic blockade and decreased systemic vascular resistance, both of which may lead to maternal hypotension and uteroplacental insufficiency. The ideal vasopressor is one which raises maternal blood pressure and improves uteroplacental blood flow.

Phenylephrine is a post-synaptic alpha-adrenergic agonist which causes vasoconstriction and a reflexive bradycardia. Phenylephrine is commonly used to increase maternal blood pressure by increasing preload and afterload after regional anesthesia or induction of general anesthesia. It is a good choice for many patients with cardiac disease because it induces a reflex bradycardia, although alternative medications should be considered in patients with regurgitant valves or ventricular failure.

Ephedrine is an indirect sympathomimetic that stimulates both alpha- and beta-adrenergic receptors, increasing blood pressure via peripheral vasoconstriction and cardiac stimulation. The beta-adrenergic activity increases heart rate, myocardial contractility, and oxygen demand, making this medication less attractive for patients with stenotic valvular lesions, coronary artery disease, and hypertrophic cardiomyopathy. More potent vasopressors, such as epinephrine and norepinephrine, may be appropriate in this patient population, but their use should be determined on an individual basis.

i. What should be recommended with regard to continuation of medications taken chronically?

• Cardiac: the pregnant cardiac patient may be on more than one cardiovascular medication, and with rare exception, cardiac medications should be continued through the peripartum period for optimal hemodynamics. The most common cardiac medications in this patient population are beta-blockers, calcium channel blockers, digoxin, hydralazine, IV prostaglandins, and antiarrhythmics. Continuing these medications through labor and into the postpartum period is appropriate and unlikely to have any significant interactions with medications administered during labor.

• Pulmonary: chronic medications should be continued through the peripartum period, including inhaled beta-agonists, inhaled steroids, systemic steroids, and supplemental oxygen.

• Renal: patients with ventricular failure or valvular lesions may be on diuretic therapy. The decision to continue these medications should be individualized to each patient. If a decision is made to hold the administration during labor, they should be initiated as soon as possible in the postpartum period to avoid volume overload.

• Anticoagulation: cardiovascular indications for anticoagulation during pregnancy include poor ventricular function, atrial fibrillation, mechanical valves, and pulmonary hypertension. Most patients who require anticoagulation during pregnancy will receive LMWH or UFH. However, some patients with mechanical valves may be maintained on warfarin for the majority of their pregnancy, and transitioned to LMWH or UFH within a week or two of the expected delivery. The decision to continue or stop anticoagulation for delivery should be made on a case-by-case basis. If anticoagulation is continued, it precludes the administration of neuraxial anesthesia. Even in patients for whom anticoagulation is temporarily held, neuraxial anesthesia should not be performed – or an epidural catheter removed – until 24 hours after the last dose of therapeutic LMWH or near-normal coagulation parameters.

• Antiplatelet therapy: low-dose (< 150 mg) aspirin therapy is thought to be safe in pregnancy, and it may be continued until delivery and should not impact placement of neuraxial anesthesia. Limited information is available regarding the safety of clopidogrel in pregnancy, and patients with acute myocardial infarction and stent placement will need antiplatelet therapy for some period of time. Stopping therapy in time for delivery may not be safe or feasible. Neuraxial anesthesia should not be performed until one week after discontinuation of therapy.

j. How To modify care for patients with known allergies –

N/A

k. Latex allergy- If the patient has a sensitivity to latex (eg. rash from gloves, underwear, etc.) versus anaphylactic reaction, prepare the operating room with latex-free products.

N/A

l. Does the patient have any antibiotic allergies- – Common antibiotic allergies and alternative antibiotics]

Please see below.

m. Does the patient have a history of allergy to anesthesia?

• Malignant hyperthermia:

  Documentedavoid all trigger agents such as succinylcholine and inhalational agents:

  Proposed general anesthetic plan: Regional anesthesia is used extensively in obstetric patients. With few exceptions, most pregnant cardiac patients will receive regional anesthesia. If general anesthesia is needed, a clean technique is recommended.

  MH protocol:

  – If a patient with documented MH is admitted to labor and delivery, a dedicated clean machine and operating room should be reserved. In addition, triggering agents (succinylcholine and volatile agents) should be removed from the room.

  Family history or risk factors for MH: Pregnant patients with cardiovascular disease are less likely to tolerate the hyperdynamic state and hemodynamic instability. MH precautions should be taken if there is any reasonable concern for MH susceptibility.

• Local anesthetics: A true local anesthetic allergy is exceedingly rare. Events that may be mistaken for an allergic reaction include vasovagal episodes with injection and intravascular injection of local anesthetic and/or epinephrine. Allergies to the metabolite of ester-type local anesthetics, or common local anesthetic additives (methylparaben and meta-bisulfite) do occur and can easily be confused with a local anesthetic allergy. A careful history is often sufficient to rule out a local anesthetic allergy, but sometimes allergy testing may be required. Neuraxial anesthesia is the mainstay of obstetric anesthesia, and the pregnant cardiac patient derives significant benefit from regional techniques. If the patient has a true local anesthetic allergy, the pharmacologic alternative for pain management is opioid medications for labor and vaginal delivery. General anesthesia or a meperidine spinal are options for cesarean delivery.

5. What laboratory tests should be obtained and has everything been reviewed?

• Complete blood count (CBC) is drawn upon admission and is needed to establish the baseline hemoglobin and hematacrit and to evaluate the platelet level to determine if neuraxial anesthesia may be placed safely.

• Blood type and antibody screen should be sent on all obstetric patients on admission. The decision to type and cross the patient should be individualized to each patient using criteria such as the starting hemoglobin, presence or absence of antibodies, likelihood of transfusion, etc.

• Patients who are anticoagulated should have the appropriate coagulation studies drawn: prothrombin time (PT) and international normalized ratio (INR) for patients on warfarin, or partial thromboplastin time (PTT) for patients on UFH. Normal, or near-normal, labs are necessary before neuraxial anesthesia can be safely placed. LMWH is monitored and adjusted using anti-factor Xa levels. Because it is not clear whether the anti-factor Xa level predicts the risk of bleeding complications, the recommend practice is to wait at least 12 hours after the last prophylactic dose, and 24 hours after the last therapeutic dose, before performing neuraxial anesthesia.

• Electrolytes may be useful in patients with arrhythmias, failure, or on chronic diuretics.

• If myocardial ischemia is suspected, troponin I is the preferred biochemical marker to diagnose or rule out ischemia.

• If preeclampsia is suspected, additional labs which may be sent include aspartate aminotransferase (AST), alanine transaminase (ALT), serum creatinine (Cr), uric acid, lactate dehydrogenase (LDH), total bilirubin, a peripheral smear, and a urine sample or timed urine collection to evaluate proteinuria.

Diagnostic studies in this patient population to review or obtain may include:

Transthoracic Echocardiography (TTE):

Patients with known cardiac disease will usually have at least one TTE during their pregnancy; review of the most recent study is prudent. If the patient has had symptomatic change in the interim, another study is indicated.

Transesophageal Echocardiography (TEE):

May be used in this patient population to rule out or diagnose an aortic dissection or endocarditis. Additionally, if a patient has a general anesthetic (for cesarean delivery or another procedure), the TEE may be helpful in guiding fluid management and obtaining real-time information about the patient’s cardiac function.

Electrocardiogram (ECG):

Should be reviewed for patients with arrhythmias and known or suspected ischemic disease.

Chest X-Ray (CXR):

May be helpful to evaluate patients with ventricular failure, pulmonary edema, or suspected aortic dissection. The fetal exposure to radiation from a single CXR is estimated to be 0.02-0.07 mrad, well below the recommended threshold of 5 rad.

Computed Tomography (CT):

Is used in to diagnose or rule out aortic dissection. A spiral CT of the chest may be used to look for evidence of a pulmonary embolus. A CT of the chest exposes the fetus to less radiation than a ventilation-perfusion lung scan. The estimated fetal radiation exposure is < 1 rad for a CT scan of the head or chest.

Cardiac Catheterization:

Should be considered in patients with symptoms of acute ischemia, concerning ECG changes, or elevated troponin levels. The amount of fetal radiation exposure will vary depending upon the length of the procedure and the number of views required for diagnosis and/or treatment.

Intraoperative Management: What are the options for anesthetic management and how to determine the best technique?

The aim of obstetric anesthesia in the cardiac patient is to reduce the stress response to labor and delivery while maintaining cardiac output and uteroplacental perfusion. This is accomplished with the combination of good pain relief, judicious fluid management, and appropriate monitoring. With few exceptions, vaginal delivery with an assisted stage is the preferred method of delivery for patients with significant cardiac disease, and cesarean delivery is reserved for obstetric indications.

For a vaginal delivery, early establishment of low-dose epidural analgesia is recommended for women who are not on therapeutic anticoagulation. Epidural anesthesia may also be employed for patients who require cesarean delivery, as it allows for slow and careful titration of the anesthetic level and tight control of the hemodynamic effects. Spinal and general anesthesia are less frequently employed in the pregnant cardiac population.

Patients who have conditions associated with higher risks of morbidity and mortality or patients with significant symptoms are most likely to benefit from invasive blood pressure monitoring and postpartum admission to an intensive care unit. The utility of central venous catheters or pulmonary artery catheters is less clear and should be individualized. Patients with known arrhythmias, or patients in whom arrhythmias would poorly tolerated (e.g. mitral stenosis, hypertrophic cardiomyopathy), should be monitored with continuous telemetry.

Regional anesthesia

is used extensively in obstetric patients.

Epidural analgesia and anesthesia

• Benefits:

  Decreases the need for systemic pain medications during labor.

  Analgesia decreases endogenous catecholamine secretion and myocardial oxygen demand and may improve uteroplacental perfusion.

  Controlling pain reduces maternal hyperventilation, minute ventilation, and oxygen consumption.

  If a laboring patient needs an operative delivery, the epidural may be used to provide surgical anesthesia.

  Compared with general anesthesia, there is a lower risk of maternal pulmonary aspiration.

• Drawbacks:

  Hypotension can occur and may produce uteroplacental insufficiency. In patients with intracardiac shunts, systemic hypotension may reverse left-to-right shunts, or worsen cyanosis in patients with right-to-left shunts. Hypotension in patients with stenotic valvular lesions or coronary disease may precipitate ischemia and failure. Lastly, in patients with hypertrophic cardiomyopathy, a drop in SVR will worsen the outflow tract obstruction and decrease the cardiac output.

  With increased intra-abdominal pressure, the epidural veins become distended, making a bloody tap or IV catheter placement more common. Unrecognized intravascular injection of local anesthetic may lead to systemic toxicity.

  Unexpected high block is possible.

  Unintended dural puncture occurs in approximately 1-2% of laboring patients.

• Contraindications:

  Patient refusal.

  Coagulation disorder, residual or continued anticoagulation, and significant thrombocytopenia.

  Infection at the site of catheter placement.

  Increased intracranial pressure, predisposing the patient to herniation.

• Technique:

  Adequate IV access and appropriate monitoring should be established. Monitors in the pregnant cardiac patient with significant disease include ECG, SpO2, invasive blood pressure monitoring, and fetal heart rate monitoring. Patients may be in the lateral decubitus or sitting position, and typically do not receive any IV sedation for placement. In select patients (e.g. patients with ischemic heart disease or severe aortic stenosis), a test dose without epinephrine may be chosen to avoid hypertension and tachycardia if the catheter is intravascular.

  For labor analgesia, an infusion of a dilute local anesthetic (e.g. 0.1% bupivacaine) with added narcotic will provide good analgesia with minimal motor block and hemodynamic consequence. Whenever a bolus dose is administered, blood pressure should be carefully monitored for 15-30 minutes, with vasopressors given as needed to maintain blood pressure and cardiac output.

  An epidural is an alternative for patients having an elective cesarean delivery, and is common in patients who transition from labor. For operative deliveries, a common choice of local anesthetic is 2% lidocaine with epinephrine. Epinephrine potentiates the block, but may be omitted in patients for whom the side effects of an inadvertent vascular injection are a concern. For patients with cardiac disease, a slow titration of the epidural with careful attention to hemodynamics is important. Epidural morphine may be given for improved post-operative analgesia.

Spinal anesthesia

• Benefits:

  Simple and reliable technique for providing anesthesia.

  Rapid onset of dense surgical anesthesia.

  Low doses of local anesthetic and opioid required for adequate block.

• Drawbacks:

  Limited duration with a single shot technique.

  With a single shot technique, slow titration of the block is not possible, consequently hemodynamic stability is difficult to ensure. Acute hypotension and reflexive tachycardia are more likely than with an epidural. As a result of the sudden decrease in SVR, patients with intracardiac shunts, stenotic valvular lesions, coronary disease, or hypertrophic cardiomyopathy may have cardiovascular compromise. Because of the potential for hemodynamic instability with spinal anesthesia, it is not commonly used for the pregnant cardiac patient with significant disease.

• Contraindications:

  Patient refusal.

  Coagulation disorder, residual or continued anticoagulation, and significant thrombocytopenia.

  Increased intracranial pressure predisposing the patient to herniation.

• Technique:

  As with epidural placement, adequate IV access and appropriate monitoring should be established prior to initiation of the procedure. The block is placed using aseptic technique with the patient in the sitting or lateral decubitus position.

  For cesarean delivery, the most common local anesthetic is 0.75% hyperbaric bupivacaine with or without narcotics. The addition of a long-acting narcotic will improve post-operative pain control, but patients should be monitored carefully to watch for signs and symptoms of respiratory depression.

  Spinal analgesia may be used during labor. Intrathecal injection of small doses of short-acting, lipophilic opioid (e.g. fentanyl) with or without a local anesthetic may be performed as a single shot technique if only short-duration analgesia is required, or in combination with epidural placement. If a combined spinal-epidural technique is chosen, avoiding intrathecal injection of local anesthetics will minimize hemodynamic effects.

  Continuous spinal analgesia may be used following intentional dural puncture with an epidural needle and threading the catheter into the CSF. This provides a route to use continuous neuraxial opioid infusion without the risk of sympathectomy associated with local anesthetics. The catheter can be dosed incrementally if cesarean delivery is needed.

General Anesthesia

General anesthesia is not commonly used in obstetric patients, but may be chosen for patients on anticoagulation who require operative delivery or in emergent situations.

• Benefits:

  Rapid induction allows surgery to be started immediately.

  May be safely performed on anticoagulated patients.

  Definitive control of the airway and ventilation can be achieved.

  In patients with cardiac disease, general anesthesia may facilitate DC cardioversion or monitoring with TEE.

  Acute falls in preload and afterload are not as dramatic as with rapid onset of neuraxial anesthesia.

• Drawbacks

  In the pregnant cardiac patient, sympathetic stimulation with laryngoscopy, hemodynamic instability at the time of induction and emergence, and negative inotropic effects of volatile agents make hemodynamic control challenging.

  In patients with Fontan physiology, positive pressure ventilation may compromise venous return, pulmonary circulation, and oxygenation.

  Volatile anesthetics cause uterine relaxation and may predispose the patient to uterine atony and postpartum hemorrhage. Postpartum hemorrhage will further reduce the SVR, making management of the cardiac patient more complex.

  Awareness under anesthesia is a concern, both during an emergent procedure and in the pregnant patient with cardiac disease.

  Anesthetic agents cross the placenta and may contribute to neonatal depression.

• Airway concerns

  Safely securing the airway in the pregnant patient population remains a concern for many practitioners, although the incidence of failed intubation may not differ significantly from the general population.

  The risk of aspiration is increased in the laboring patient.

Monitored Anesthesia Care

Monitored anesthesia care is rarely used in this patient population, as pain control will be inadequate for labor analgesia or cesarean delivery.

• Benefits:

  May provide adequate analgesia for short procedures.

  Avoidance of general or neuraxial anesthesia.

  Can be used in patients who require intrapartum anticoagulation.

• Drawbacks:

  Insufficient for assisted second stage or operative delivery.

  Will decrease respiratory rate and increase pCO2, which can lead to an increase in pulmonary artery pressures. Patients with intracardiac shunts, pulmonary hypertension, and Fontan physiology may not tolerate additional increases in right-sided pressure without compromise.

  Does not control the sympathetic response to pain; consequently, heart rate, cardiac output, and myocardial oxygen demand will increase.

  The unsecured airway in a pregnant patient predisposes them to aspiration.

  Will cross the placenta, and may contribute to neonatal depression.

6. What is the author's preferred method of anesthesia technique and why?

Although any technique may be performed in pregnant patients with cardiac disease, the preferred technique is an epidural anesthetic. Epidural anesthesia allows for excellent pain control in labor, slow and careful titration of the sensory level, and a smooth transition to a surgical block in the event that a cesarean delivery is necessary.

What do I need to know about the surgery to optimize my anesthetic care?

In patients with cardiac disease, epidural anesthesia should be established early in labor or before an induction of labor.

• For labor analgesia, a dilute local anesthetic with a narcotic will provide good pain control with minimal hemodynamic effects. The anesthetic may be delivered via a continuous infusion, or patient-controlled epidural analgesia with intermittent patient-initiated boluses. Patients with cardiac disease should be carefully monitored during the initiation of anesthesia and throughout labor.

• An assisted second stage with forceps or a vacuum may require a denser block to tolerate the instrumentation. A small epidural bolus of a concentrated local anesthetic (e.g., 2% lidocaine with epinephrine) with or without the addition of a short-acting lipophilic narcotic like fentanyl will improve the quality of the block and facilitate the assisted delivery.

• For a cesarean delivery, administration of a concentrated local anesthetic in repeated doses and titrated to affect, will provide surgical anesthesia. The level may be reached slowly (especially if using bupivacaine or ropivacaine), allowing appropriate time to minimize hemodynamic changes.

What are the most common intraoperative complications and how can they be avoided/treated?

Systemic hypotension is a common side effect or complication of both neuraxial anesthesia and general anesthesia, and will be poorly tolerated by most cardiac patients. Slow titration of an epidural is one option for minimizing the hemodynamic effects of anesthesia. Other important maneuvers include left uterine displacement or lateral decubitous position to avoid aortocaval compression and judicious use of IV fluids and vasopressors.

Postpartum hemorrhage is another complication. Uterine atony is the most common cause of postpartum hemorrhage. Patients with underlying cardiac disease who will not tolerate a sudden or significant drop in SVR (e.g., stenotic valvular lesions, intracardiac shunts, etc.) need aggressive treatment and resuscitation in the event of a postpartum hemorrhage.

Following delivery, mechanical maneuvers (e.g., uterine massage) will help improve uterine tone. In most patients, an oxytocin infusion will be started immediately after delivery to improve tone and minimize blood loss. Other uterotonic agents and resuscitative fluids or blood products should be administered as indicated.

Antibiotic administration

a. Routine prophylaxis

1. Vaginal delivery: Antibiotics are not routinely given for vaginal delivery. Antibiotics may be given during labor for neonatal protection against Group B Streptococcus infection in preterm patients or in women who are known to be colonized with the bacteria.

2. Cesarean delivery: Typical surgical prophylaxis is a first generation cephalosporin, such as cefazolin 1 to 2 grams IV, given prior to skin incision.

b. Endocarditis prophylaxis

1. Routine endocarditis prophylaxis is not recommended for vaginal or cesarean delivery in the absence of infection. Current recommendations are for endocarditis prophylaxis only in patients who have cardiac conditions associated with the highest risk of adverse outcomes and an established infection which could cause bacteremia (e.g., chorioamnionitis).

2. Cardiac lesions considered to be high risk for adverse outcomes include prosthetic heart valves, history of endocarditis, unrepaired cyanotic congenital heart disease (with or without palliative shunts), repaired congenital heart disease with residual defects adjacent to prosthetic material, completely repaired congenital lesions with prosthetic material within 6 months of the repair, and cardiac transplant patients with valvulopathy.

3. Appropriate IV antibiotic choices for endocarditis prophylaxis 30 to 60 minutes prior to the procedure include ampicillin 2 grams or cefazolin or ceftriaxone 1 gram.

c. The patient with antibiotic allergies

1. Routine prophylaxis: For patients undergoing a cesarean delivery with a significant allergy (e.g., anaphylaxis) to cephalosporins or penicillin, clindamycin 600 mg IV is a reasonable alternative.

2. Endocarditis prophylaxis: For patients with an insignificant penicillin allergy, cefazolin or ceftriaxone 1 gram IV 30 to 60 minutes prior to the procedure is an acceptable alternative. If a significant reaction (e.g., anaphylaxis) is reported, clindamycin 600 mg should be given IV 30 to 60 minutes prior to the procedure.

a. Neurologic:

N/A

b. If the patient is intubated, are there any special criteria for extubation?

Standard criteria for extubation may be applied in this population.

Cardiopulmonary resuscitation in the parturient

Although cardiopulmonary resuscitation is a rare event in pregnancy, patients with preexisting cardiac disease are at increased risk over the general obstetric population. In general, standard advanced cardiac life support (ACLS) protocols are unchanged for pregnant women, and maternal resuscitation is the best therapy for the fetus. Vasoactive medications and defibrillation should be administered as in the nonpregnant population.

Important considerations unique to the parturient include:

a. Airway: The pregnant patient should be intubated soon after initiation of cardiopulmonary resuscitation (CPR) to protect the airway from aspiration and facilitate oxygenation and ventilation.

b. Circulation: Cardiac output is significantly affected by patient positioning after 20 weeks gestation. Aortocaval compression by the gravid uterus can significantly compromise preload and cardiac output. A critical component of resuscitation in the obstetric population involves left uterine displacement, accomplished with a wedge or pillow under the patient’s right hip, or by manual displacement of the uterus to the left.

c. Delivery: If cardiac arrest occurs before 24 weeks gestation (age of fetal viability), the rescuer’s efforts should be directed exclusively toward the mother. If arrest occurs after 24 weeks, the fetus should be delivered within 5 minutes of initiation of CPR if CPR has not been successful in establishing a cardiac rhythm. Prompt delivery minimizes the risk of hypoxic insult to the fetus and improves maternal cardiac output by relieving aortocaval compression, decreasing metabolic demands, and allowing for more effective chest compressions. Delivery may be considered even in a nonviable pregnancy to improve resuscitation of the mother.

d.Venous access should be secured in the upper extremities.

c. Postoperative management

What analgesic modalities can I implement?

Vaginal delivery:

• Most patients who have a vaginal delivery will require only oral pain medications, such as non-steroidal anti-inflammatory medications (NSAIDs), acetaminophen, or acetaminophen-narcotic combinations. However, patients with extensive lacerations and repairs may have more significant pain and could benefit from parenteral or epidural narcotics. If either option is chosen, patients should be closely monitored for any evidence of respiratory compromise. Postpartum anticoagulation may prevent use of NSAIDs and epidural analgesia.

Cesarean delivery:

• Patients who have a neuraxial anesthetic for their surgery will most commonly have epidural or intrathecal morphine for post-operative pain control. As above, if epidural morphine is administered, patients should be carefully monitored for evidence of respiratory depression. Patients who have a general anesthetic for their delivery will most likely need IV narcotics, administered via a patient-controlled analgesia (PCA) pump, or given as needed by care providers. Use of adjunctive medications (NSAIDs or acetaminophen) is helpful and will reduce the amount of narcotics administered. TAP blocks under ultrasound guidance also provide effective post-cesarean pain relief.

What level bed acuity is appropriate?

• Patients with cardiac disease may deliver on a general obstetric unit or they may require intensive management and intensive care. The decision of where the patient should go for the immediate postpartum period should be individualized in discussion with her cardiologist. In general, patients with significant disease or complicated deliveries (e.g. uterine atony and hemorrhage) will benefit from intensive care.

What are common postoperative complications, and ways to prevent and treat them?

Volume overload:

• Immediately after delivery, cardiac output peaks. Although cardiac output will return to prelabor levels within several hours, circulating volume will remain high as extravascular fluid is mobilized. Patients with limited ability to increase their cardiac output or to tolerate an increase in intravascular volume must be carefully observed. Patients at particular risk in the postpartum period include those with pulmonary hypertension, ventricular failure, mitral stenosis, and a single ventricle.

Thromboembolic events:

• Pregnancy is a hypercoagulable state, and the first 3 to 5 days postpartum may be associated with a further increase in coagulation. The coagulation profile returns to the nonpregnant state within two weeks postpartum. Patients at risk for thromboembolic events (e.g. pulmonary hypertension, ventricular failure, atrial fibrillation, and mechanical valves) should be restarted on prophylactic or therapeutic anticoagulation as soon as it is safe to do so in the postpartum period – typically 6 hours after vaginal delivery and 12 hours after cesarean delivery. Removal of an epidural catheter must be coordinated with the obstetric service who is ordering her anticoagulant medications.

What's the Evidence?

Anesth Analg. vol. 113. 2011. pp. 307-17. A case series of the anesthetic management of parturients with surgically repaired tetralogy of Fallot.(Review of management of this lesion in several cases.)

J Am Coll Cardiol. vol. 48. 2006. pp. e1-148. (Not specific to pregnancy, but national recommendations from ACC.)

Curr Opin Crit Care. vol. 11. 2005. pp. 430-4. (Good review of optimization during pregnancy.)

Curr Opin Crit Care. vol. 11. 2005. pp. 435-48. (Good review of the management of these lesions during pregnancy.)

Anesthesiology. vol. 114. 2011. pp. 949-57. Case scenario: cesarean section complicated by rheumatic mitral stenosis.(An example of a management plan for this lesion.)

Br J Anaesth. vol. 93. 2004. pp. 428-39. (Another excellent review of the management of these lesions during pregnancy.)

Int J Obstet Anesth. vol. 15. 2006. pp. 137-44. (Review of the management of congenital lesions.)

Int J Obstet Anesth. vol. 19. 2010. pp. 306-12. (Review of antepartum and intrapartum management of these lesions.)

J Am Coll Cardiol. vol. 52. 2008. pp. 171-80. (Case review and management of MI during pregnancy.)

BJOG. vol. 118. 2011. pp. 345-52. Chronic heart disease and severe obstetric morbidity among hospitalisations for pregnancy in the USA: 1995-2006.(Chronic heart disease and outcomes during pregnancy.)

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