Pregnancy and Cardiac Considerations

Physiological Considerations in Pregnancy

• Marked pregnancy-induced anatomical and functional changes in cardiac physiology can profoundly affect underlying heart disease.
• Cardiac output increases by approximately 40% during pregnancy.
  • This increase takes place by 8 weeks and is maximal by mid-pregnancy.
  • The early rise stems from augmented stroke volume, resulting from lowered vascular resistance.
  • Greater end-diastolic ventricular volume results from pregnancy hypervolemia, leading to higher resting pulse and stroke volume.
• Normal left ventricular function is maintained.
• Pregnancy is not characterized by hyperdynamic function or a high cardiac output state.

Cardiac Disorders

• Includes congenital and acquired heart diseases/defects.
• Better care, screening, and surgical correction of defects mean that pregnant women with heart disease are identified more frequently today.

Effects and Incidence of Heart Disease on Pregnancy

• Pregnancy alters heart rate, blood pressure, and cardiac output.
• Incidence: 0.5%-2% of all pregnant women.

Predisposing Factors

• Syphilis, arteriosclerosis, renal and pulmonary disease, rheumatic fever, congenital heart defects, and surgical repair of defects.

Prognosis

• Depends on the heart's functional capacity.
• Complications that further increase cardiac load affect prognosis.
• The quality of healthcare is a factor.
• Maternal and fetal risk increases from NYHA Classes 1 to 4; women in Classes 3 and 4 will have serious problems in pregnancy.

NYHA Functional Heart Disease Classification

• Class I: Uncompromised, no limitation of physical activity nor symptoms of cardiac insufficiency or anginal pain.
• Class II: Slight limitation of physical activity; comfortable at rest, but ordinary physical activity results in discomfort (excessive fatigue, palpitation, dyspnea, or anginal pain).
• Class III: Marked limitation of physical activity; comfortable at rest, but less than ordinary activity causes excessive fatigue, palpitation, dyspnea, or anginal pain.
• Class IV: Severely compromised; inability to perform physical activity without discomfort; symptoms of cardiac insufficiency or angina may develop even at rest.

Modified World Health Organization (WHO) Classification of Maternal Cardiovascular Risk

• Risk classes exist for maternal mortality and morbidity.
• Classes range from no detectable increase in risk to extremely high risk, where pregnancy is contraindicated.
• Expert counseling and intensive monitoring may be needed in certain cases.

Pregnancy and Cardiac Disease

• The danger of pregnancy in a woman with cardiac disease occurs primarily due to increased circulatory volume.
• The most dangerous period is weeks 28 to 32, just after blood volume peaks.
• If heart disease is severe, symptoms can occur as early as the beginning of pregnancy.

Ventricular Function in Pregnancy

• Ventricular volumes and mass increase to accommodate pregnancy-induced hypervolemia.
• This change is reflected by greater end-systolic and end-diastolic dimensions.
• Adaptations return to pre-pregnancy values within a few months postpartum.

Diagnosis of Heart Disease - Symptoms

• Progressive dyspnea.
• Orthopnea.
• Nocturnal cough.
• Hemoptysis.
• Syncope.
• Chest pain.

Diagnosis of Heart Disease - Signs

• Cyanosis.
• Clubbing of fingers.
• Persistent neck vein distention.
• Systolic murmur grade 3/6 or greater.
• Diastolic murmur.
• Cardiomegaly.
• Persistent tachycardia and/or arrhythmia.
• Persistent split-second sound.
• Fourth heart sound ('atrial gallop', from atrial contraction pushing blood into a stiff ventricle).
• Criteria for pulmonary hypertension.

Labor and Delivery

• Vaginal delivery is preferred with labor induction being usually safe.
• Cesarean delivery is recommended for specific conditions.
  • Dialated aortic root >4 cm or aortic aneurysm or acute severe congestive heart failure.
  • Recent myocardial infarction or severe symptomatic aortic stenosis.
  • Warfarin administration within 2 weeks of delivery or the need for emergency valve replacement immediately after delivery.

During Labor

• During labor, the mother should be in a semi-recumbent position with a lateral tilt.
• PR >100 beats/minute and RR > 24/minute + dyspnea → ventricular failure.
• Delivery does not necessarily improve the maternal condition.
• Emergency cesarean delivery may be particularly hazardous.

Analgesia and Anesthesia

• Relief from pain and apprehension is important.
• Continuous epidural analgesia is recommended.

Major Problem - Maternal Hypotension

• Narcotic regional analgesia or general anesthesia may be preferable.
• Subarachnoid blockade (spinal anesthesia) is not recommended due to associated hypotension.
• Epidural analgesia is preferred by most clinicians for cesarean delivery.

Anticoagulation Recommendations

• Heparin is discontinued just before delivery.
• Protamine sulfate is given intravenously if extensive bleeding occurs during heparin administration.
• Anticoagulant therapy may be restarted 6 hours after vaginal delivery (usually without problems).
• ACOG advises resuming unfractionated or low-molecular-weight heparin 6-12 hours after cesarean delivery.

Additional Prognosis Information

• Pregnancy is contraindicated with severe disease, especially pulmonary artery changes.
• Prognosis is better with milder forms than other causes, and pregnancy is reasonably well tolerated.
• Pulmonary hypertension's final common pathway is right heart failure and death regardless of the etiology. The average survival length after diagnosis is <4 years.

Symptomatic Treatment

• Activity limitation, avoiding the supine position (orthopneic position for dyspnea).
• Diuretics, supplemental oxygen and pulmonary vasodilator drugs.
• Relief from pain and apprehension is important as well as anticoagulation from Heparin.
• During labor, women are at great risk when venous return and right ventricular filling are diminished.
• To avoid hypotension, assiduous attention is given to epidural analgesia induction and to blood loss prevention and treatment at delivery.