Case Report

Use of Intra-Aortic Balloon Counterpulsation During Emergent Cesarean Section in a Pregnant Patient with Myocardial Infarction

Mahazarin Ginwalla, MD, Dilip Pillai, MD, Sanjay Gandhi, MD
Mahazarin Ginwalla, MD, Dilip Pillai, MD, Sanjay Gandhi, MD
   ABSTRACT: The intra-aortic balloon pump (IABP) is a tool to help improve myocardial perfusion, reduce afterload, and decrease myocardial demand by reducing cardiac work. We describe a unique case of an IABP placement in a pregnant woman in her third trimester with a non-ST elevation myocardial infarction. The IABP allowed safe delivery of the fetus by cesarean section prior to a successful percutaneous intervention for complex two-vessel coronary artery disease. This case report also describes the first-time use of an IABP during cesarean section. J INVASIVE CARDIOL 2010;22:E104–E106    Key words: intra-aortic balloon pump (IABP), non-ST elevation myocardial infarction (NSTEMI)    The intra-aortic balloon pump (IABP) has emerged as an effective and widely used invasive circulatory assist device. It produces its hemodynamic effects by inflating during diastole, thereby displacing blood from the descending aorta, and then deflating immediately before systole, creating a void in the aorta.1 This diastolic inflation leads to a rise in aortic pressure that improves coronary perfusion pressure and flow, referred to as diastolic augmentation. Increased coronary blood flow is most enhanced in coronary vascular beds maximally dilated by ischemia, as in this setting, autoregulation is at a maximal level and flow becomes pressure-dependent.2 Left ventricular work is also reduced by the reduction in afterload, which translates into decreased myocardial oxygen demand.1    The incidence of acute MI has been found to be 6.2 in 100,000 pregnancies, with a 3- to 4-fold increase as compared to non-pregnant women. In addition to the risk factors encountered in non-pregnant women like smoking, diabetes, hypertension, and advanced age, thrombophilia and post-partum infection also appear to be independent risk factors. Most cases occur in the third trimester and six-week post-partum period, and commonly involve the anterior wall. Coronary artery morphology evaluated by arteriography and autopsy revealed the presence of coronary atherosclerosis with or without intracoronary thrombus in 43%, thrombus in a normal coronary artery (21%), coronary artery dissection (16%), and normal coronary arteries (29%). Early diagnosis is often hindered by the normal changes of pregnancy and low clinical suspicion.3    We report the case of a 34-year-old pregnant woman with non-ST elevation myocardial infarction (NSTEMI) and complex two-vessel coronary artery disease (CAD) whose child was delivered safely by an emergent C-section after placement of an IABP. She subsequently had successful percutaneous intervention with placement of bare metal stents and was discharged home without any recurrence of her symptoms.    Case Report. A 34-year-old female with history of obesity, smoking, and sleep apnea was admitted during the 34th week of her third pregnancy for evaluation of exertional chest pain and dyspnea of 4 weeks duration. Her chest pain episodes had recently become more frequent and she had a few episodes of chest pain at rest leading to admission for unstable angina. On admission, the patient’s blood pressure was 99/55 mmHg and her heart rate was 109 bpm. Her initial troponin was elevated at 0.54 (normal limit up to 0.120). There were no significant acute ischemic ECG changes. A transthoracic echocardiogram did not show any significant wall motion abnormality or valve disease with an estimated left ventricular ejection fraction (LVEF) of 65%. Given her advanced pregnancy with ongoing angina despite medical therapy, the decision was made to proceed with coronary angiography after discussion with the patient and her obstetrician. The patient was brought to the catheterization laboratory with fetal monitoring. Limited angiography was performed revealing significant two-vessel coronary artery disease (CAD) (Figures 1A and 2A) with complex bifurcation stenosis of the LAD and diagonal branch and tubular 70% stenosis in an obtuse marginal branch. Given her coronary anatomy, the therapeutic options at this stage included complex PCI prior to delivery or coronary artery bypass surgery (CABG). She was not considered to be a candidate for PCI given her near delivery and inability to take clopidogrel and it was felt that CABG would also jeopardize fetal circulation.    After discussion with her obstetrician, primary cardiologist, and the CT surgery service, it was felt that that best approach would be to deliver the baby by cesarean section and proceed to revascularization. A prophylactic intra-aortic balloon pump (Datascope Cardiac Assist, Fairfield, New Jersey) was placed because of her high-risk disease and increased cardiac demands during C-section. A C-section was preferred over normal vaginal delivery as she had already had a C-section with an earlier pregnancy and because the expected cardiac output increase during C-section would be much higher than that during a normal vaginal delivery.    She had an emergent C-section under epidural anesthesia the following day. Following the C-section, she was monitored closely in the cardiac intensive care unit. She remained free of chest pain. The IABP was kept on 1:1 augmentation. It was weaned and removed four days later as she remained chest-pain free. Her post- operative course was complicated by abdominal wound dehiscence, for which she had to be taken back to the OR.    Due to her poor wound healing, recent abdominal wound de- hiscence, and obesity, PCI was preferred for revascularization rather than CABG. She was taken back to the catheterization lab for intervention. A 3.5 x 18 mm bare-metal stent (Multi-Link Vision®, Abbott Vascular, Santa Clara, California) was placed in the proximal LAD with occlusion of the small second diagonal (Figure 1B). The tubular lesion of the proximal large obtuse marginal artery was covered with a 3.5 x 15 mm bare metal stent (Multi-Link Vision, Abbott Vascular, Figure 2B). Bare metal stents were preferred due to her psychosocial issues and previous non-adherence to medications. The patient did well post PCI and was discharged home in stable condition. She was also doing well at her thirty-day follow-up visit.    Discussion. Myocardial infarction is an uncommon event during pregnancy, but it can have devastating consequences for the mother and baby. The effects of an IABP on the fetal circulation are unknown and its use in pregnant patients is limited. We describe the successful implantation of an IABP in a woman in her mid-third trimester of pregnancy with significant CAD and acute NSTEMI. The IABP allowed successful delivery of her fetus by C-section. No bleeding or vascular complications secondary to IABP use were encountered in our patient.    Allen et al reported the first use of the IABP in a pregnant woman in her third trimester with an anterior wall infarction in 1990.4 Since then, there has been only one other report of its use in a pregnant patient with an acute anterior myocardial infarction at 25 weeks pregnancy to bridge her to CABG.5 Despite limited experience in this patient population, it appears to be a useful tool in pregnant patients with ongoing ischemia and significant CAD. Willcox et al report the use of the IABP to improve uterine perfusion and relieve profound fetal bradycardia after termination of a long cardiopulmonary bypass operation. They also used it to provide pulsatile flow during a bypass surgery to improve fetal hemodynamics.6 Thus, the IABP may also help optimize fetal hemodynamics and blood flow in addition to improving maternal hemodynamics.    Sudden and significant hemodynamic changes occur at the moment of delivery, whether natural or by cesarean section. During normal vaginal labor and delivery, cardiac out-put increases by 25% during the active phase of labor, up to 50% during the pushing phase, and up to 80% immediately after delivery.7 At the point of delivery by C-section, there is a 47% increase in cardiac output and a 39% decrease in systemic vascular resistance index. These changes occur within 2 minutes of delivery, and persist for 10 minutes on average post delivery. Thus, intact physiological cardiovascular compensation mechanisms are important to adapt to these changes.8    The use of the IABP in early postpartum patients has been limited. The IABP may help stabilize the coronary circulation during the increased demands associated with delivery and early postpartum, as demonstrated by our patient. Previously, it has been used successfully in postpartum myocardial infarction9 and postpartum-hemorrhage-associated cardiac failure.10    This case underscores the importance of quick intervention and stabilization of pregnant patients with severe CAD to relieve ongoing ischemia and improve feto-maternal out-come. This case illustrates the safe use of IABP in a patient with advanced pregnancy.

References

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_________________________________________________ From the Division of Cardiology, Case Western Reserve University-Metro-Health Medical Center, Cleveland, Ohio. The authors report no conflicts of interest regarding the content herein. Manuscript submitted October 2, 2009, provisional acceptance November 3, 2009, final version accepted November 12, 2009. Address for correspondence: Sanjay Gandhi, MD, Department of Cardiology, Case Western Reserve University-MetroHealth Medical Center, Cleveland, OH 44109. E-mail: sgandhi@metrohealth.org