Caesarian Dissection

Abstract

Forward Information about a real patient is presented in stages (boldface type) to an expert clinician (Dr Nandita S. Scott), who responds to the information, sharing her reasoning with the reader (regular type). A discussion by the authors follows.A 35-year-old woman, G2P1, with a history of Hashimoto's thyroiditis, vitiligo, and gestational diabetes mellitus presented in the 30th week of pregnancy with premature labor. She was admitted to the obstetrics service for monitoring and tocolytic therapy. On hospital day 2, the patient complained of chest heaviness and left arm discomfort, but her assessment was confounded by pain secondary to frequent uterine contractions. On hospital day 3, fetal monitoring disclosed a nonreassuring fetal heart rate pattern, prompting transfer to the operating room for urgent Caesarian section. A viable female infant was delivered, but the immediate postoperative course was complicated by acute dyspnea, coughing, and hypoxia.Dr Nandita S. Scott: Dyspnea is quite common during pregnancy as a result of physiological changes including weight gain, dilutional anemia of pregnancy, and progesterone-induced hyperventilation. This can make the distinction between pathology and normal dyspnea of pregnancy difficult. In contrast, hypoxia during pregnancy is never normal. The cardiac causes of hypoxia in the peripartum period can be broadly separated into 2 categories: congestive heart failure from preexisting cardiac conditions (eg, cardiomyopathy, valvular disease, or congenital heart disease) or congestive heart failure attributable to pregnancy-induced cardiac conditions (eg, peripartum cardiomyopathy or acute ischemic events). Pulmonary causes such as pulmonary embolism and amniotic fluid embolism also need to be considered.Pregnancy poses a large hemodynamic burden on the cardiovascular system. A 30% to 50% rise in blood volume and cardiac output, increase in heart rate, reduction in systemic vascular resistance resulting from the low-resistance placental unit, physiological anemia, and positional reduction in cardiac output attributable to compression of the inferior vena cava all contribute to stress the heart. 1 Pregnancy may therefore unmask a preexisting cardiac condition that was unknown before conception. At delivery, this hemodynamic burden increases further as a result of the autotranfusion of uteroplacental blood, tachycardia from pain, and the loss of the low-resistance placental unit. Consequently, the cardiovascular adaptations of pregnancy remain clinically relevant after delivery of the fetus. Indeed, it may be months before the circulation fully returns to normal.This patient had no preexisting cardiac conditions that we are aware of. On hospital day 2 she developed chest pain, which suggests a possible ischemic cause for her symptoms. Peripartum cardiomyopathy is a less likely explanation for her symptoms, because this patient was only 30 weeks pregnant and peripartum cardiomyopathy occurs most often in the last month of pregnancy and the first 5 months after delivery.I...