Hypertrophic cardiomyopathy management during pregnancy

Editors-In-Chief: C. Michael Gibson, M.S., M.D. [mailto:mgibson@perfuse.org]

Overview
Women with hypertrophic cardiomyopathy should be managed by a skilled cardiovascular specialist and a high-risk obstetrician during pregnancy. Any activity, drug or circumstance that increases left ventricular outflow obstruction, reduced left ventricular filling, or increases left ventricular afterload should be avoided.

Natural History, Complications And Prognosis In The Hypertrophic Cardiomyopathy Patient During Pregnancy
Among HCM patients who chronically have mild symptoms, pregnancy is generally well tolerated. Although pregnancy causes vasodilation which should exacerbate the outflow gradient, pregnancy also causes fluid retention and an increase in plasma volume which increases preload and offsets the reduction in afterload. In a series of 100 HCM patients, only one of 28 asymptomatic patients developed NYHA Class III or IV heart failure. Among 12 previously symptomatic patients, 5 patients developed NYHA Class III or IV heart failure. It is notable that two sudden deaths occurred in this series of 100 patients. One of the two patients had a resting gradient of 115 mm Hg. The other patient had a markedly positive family history with 8 family members sustaining any early death, 5 of which were sudden death.

Avoid Activities That Increase Left Ventricular Outflow Tract Obstruction
The following activities increase left ventricular outflow tract obstruction and should be avoided:
 * Epidural Anesthesia Should Be Avoided due to the potential for venous pooling.
 * Bleeding should be minimized. Blood should be crossed and typed in case a transfusion is needed for bleeding, which can exacerbate outflow obstruction.
 * Nausea and vomiting
 * Dehydration
 * Hypovolemia (i.e., use diuretics with caution)
 * Medications that reduce preload and left ventricular filling such as nitrates

Avoid Activities That Increase Afterload
The following activities increase left ventricular afterload should be avoided:
 * Intense isometric exercise

Beta Blockade and Calcium Channel Blockade
Although both beta blockers and verapamil may improve symptoms in the mother, the dosing should be limited to minimize the risk of fetal bradycardia, growth retardation and hypoglycemia. There is more experience with the use beta blockers during pregnancy.

Home Delivery Should Be Avoided
Home delivery without IV access is not preferred.

Vaginal Delivery Versus C-Section
Vaginal delivery is usually successful.