A 44-year-old female, G1P0, at 36 weeks gestation presents with worsening shortness of breath, lower extremity edema, and fatigue. Vital signs are notable for blood pressure of 84/58 mm Hg, heart rate of 144 beats per minute, respiratory rate 38 breaths per minute, and oxygen saturation of 92% while breathing room air. Examination is notable for 2+ bilateral lower-extremity pitting edema and bibasilar rales extending one-third of the way up bilateral lung fields. Urinalysis shows no protein and indices of renal and hepatic function are normal. Diuretics and afterload reduction with hydralazine and nitrates are started. Echocardiography shows left ventricular dilatation and severe left ventricular dysfunction with ejection fraction of 15%. Cesarean section delivery is performed, but her hemodynamics continue to worsen. Further diagnostic testing including coronary angiography at time of pulmonary artery catheter placement does not reveal alternate etiology, but she is noted to have a cardiac output of 2.1 L/min (cardiac index of 1.3 L/min/m2 ). Unfortunately, her clinical condition worsens and she develops progressive cardiogenic shock refractory to medical therapy including norepinephrine, milrinone, and epinephrine.
The most appropriate next step in management is:
A. PhenylephrineCorrect Answer: C
Peripartum cardiomyopathy is a condition that can occur from 1 month before delivery up to 5 months following delivery and is characterized by left ventricular ejection fraction <45%, and no prior history of cardiac disease. Peripartum cardiomyopathy is a diagnosis of exclusion and other causes of heart failure must be exonerated. Diagnostic testing should be driven by an interdisciplinary team and often includes transthoracic echocardiography, as well as cardiac MRI, endomyocardial biopsy, and coronary angiography. Cardiac workload increases during pregnancy as a result of increased circulating volume, heart rate, and stroke volume. This results in a net increase in cardiac output of approximately 20% to 50%. Vascular resistance decreases by about 20% but rises in the third trimester.
Management of peripartum cardiomyopathy is similar to management of other etiologies of heart failure, but with mindfulness regarding teratogenicity of medications. During the gravid period, beta blockers and hydralazine may be used for medical afterload reduction under close monitoring to avoid decreases in uretoplacental perfusion. The main stays in medical management following delivery are ACE inhibitors and beta blockers. Optimization of volume status and management of anemia are additional considerations in management. Peripartum cardiomyopathy is associated with atrial and ventricular arrhythmias, the most common of which is atrial fibrillation.
As with other cardiomyopathies, management of patients with shock and clinical instability should include vasopressors and inotropes. However, phenylephrine should be avoided as it primarily increases afterload without providing inotropy. Appropriate consideration of mechanical circulatory support includes ventricular assist devices and extracorporeal membrane oxygenation, whether as a bridge to recovery or transplantation. For patients with hemodynamic instability, cesarean delivery is preferred to minimize hemodynamic stressors of vaginal birth. Over 50% of women with peripartum cardiomyopathy eventually recover ejection fraction. However, some will require mechanical support as a bridge to transplant or recovery. Those requiring mechanical support have better survival than women with other nonischemic or ischemic cardiomyopathies.
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