A Rapidly Evolving Case of Syncope During Pregnancy
Patient presentation: A 25-year-old G2P1001 woman in her 36th week of pregnancy presented to the emergency department after experiencing a syncopal episode at home. Approximately 3 weeks previously, she began to experience progressive dyspnea at rest that was exacerbated by exertion and associated with chest discomfort. Further review of systems was negative for cough, abdominal pain, vaginal discharge, and neurologic deficit. Her obstetric and medical history was notable for iron deficiency anemia. Medications included oral ferrous sulfate and a prenatal vitamin. There was no personal or family history of cardiac or clotting disorders.
In the emergency department, the patient appeared uncomfortable and anxious. Her heart rate was 119 and blood pressure was 94/55 mm Hg. Oxygen saturation was 94% while breathing room air and body mass index was 27 kg/m2. Cardiac examination revealed a regular tachycardia without murmurs or gallops. Lung sounds were clear bilaterally. The abdomen was soft and gravid, without tenderness or contusion. Extremities were warm, with intact distal pulses. There was no peripheral edema.
在急诊室，患者显得不舒服和焦虑。她的心率是119，血压是94/55mmHg。呼吸室内空气时的氧饱和度为94％，体重指数为27 kg / m 2 。心脏检查发现正常心动过速，没有杂音或奔马律。两侧的肺音清晰。腹部柔软，无压痛或挫伤。四肢温暖，远端脉搏完整。没有周围水肿。
Abnormal basic laboratory test results included a hemoglobin level of 9.4 g/dL (third trimester reference, 9.5 to 15.0 g/dL) and a cardiac troponin I level of 0.17 ng/mL (reference, 0.00 to 0.04 ng/mL). Otherwise, blood work was normal, including platelets, serum sodium and creatinine, liver function tests, thyroid-stimulating hormone, and plasma brain natriuretic peptide. Admission ECG showed sinus tachycardia with a rightward axis, S1Q3T3 pattern, and additional T-wave inversions in leads V1and V2.
Patient presentation (continued): Computed tomographic pulmonary angiography was obtained and revealed a thin saddle PE (Figure 1A) with extensive thrombus burden in the left (Figure 1B) and right (Figure 1C) main pulmonary arteries (PAs). There was further extension into the lower lobar, segmental, and subsegmental segments. The right ventricle (RV) was severely dilated with a right to left ventricular ratio of 1.5 and bowing of the interventricular septum into the left ventricle (Figure 1D). Transthoracic echocardiogram (Figure 2) showed a hyperkinetic RV apex and a hypokinetic RV free wall (McConnell sign).
Figure 1.Computed tomographic pulmonary angiography obtained on admission showing saddle pulmonary embolism with large thrombus burden bilaterally.A, Thin saddle embolism extending over the bifurcation of the main pulmonary artery with more extensive thrombus burden (black arrows) in the left main (B) and right main (C) pulmonary arteries. D, Severely dilated right ventricle with a right-to-left ventricular ratio of approximately 1.5, suggestive of right ventricle strain.
Figure 2.Transthoracic echocardiogram on admission.A, Parasternal short axis view at end-systole showing a severely dilated right ventricle (RV). B, Apical 4-chamber view at end-systole showing severe RV dilation and interventricular septum flattening, suggestive of RV strain. C, RV-focused view at end-systole. In motion, the RV apex was hyperkinetic and free wall hypokinetic (McConnell sign). D, Continuous wave Doppler through the tricuspid valve demonstrating at least moderate tricuspid regurgitation and elevated pulmonary arterial pressures. bpm indicates beats per minute; PG, peak gradient; and Vel, velocity.
Therapeutic anticoagulation was initiated, and the patient was admitted for continuous hemodynamic monitoring. The PE response team and maternal–fetal medicine services were consulted. At hour 7 of admission, the patient developed painful uterine contractions consistent with the initiation of spontaneous labor. She remained hemodynamically stable and was transferred urgently to the labor and delivery unit.
The patient gave birth to a viable newborn through normal spontaneous vaginal delivery at hour 19 of admission without complication. Her tachycardia subsequently resolved and the remainder of her hemodynamic parameters remained stable. She was transferred to a general medical floor with continuous cardiac telemetry.
At hour 45 of admission, the patient experienced a witnessed cardiac arrest. Return of spontaneous circulation was achieved after 8 minutes of cardiopulmonary resuscitation, although persistent hypotension required the initiation of vasopressor support. During resuscitative efforts, the patient was intubated emergently and cannulated for VA-ECMO. A subsequent transthoracic echocardiogram showed new biventricular dysfunction. The left ventricle demonstrated global hypokinesis with a left ventricular ejection fraction of 26%. The RV was severely dilated with a moderate decrease in systolic function. There was diastolic flattening of the interventricular septum, consistent with RV overload.
At hour 63 of admission, the patient was taken to the cardiac catheterization laboratory for catheter-based embolectomy while on VA-ECMO. The PA angiography demonstrated significant occlusive thrombus burden in the distal left and right main PAs, with impaired bilateral lower lobe perfusion (Figure 3A). A large-bore catheter-based device that mechanically engages thrombi for manual aspiration (FlowTriever System; Inari Medical, Irvine, CA) was used to perform aspiration embolectomy of the right main PA and upper lobar arteries and the left distal main PA and interlobar artery. A final PA angiogram showed improved perfusion in the bilateral PAs and lung fields (Figure 3D). VA-ECMO was weaned over the next 3 days. The patient was decannulated, extubated, and weaned off vasopressor support. Her mental status was at baseline. A repeat transthoracic echocardiogram showed normal RV and left ventricle size and function with left ventricular ejection fraction of 71% and RV systolic pressure of 28 mm Hg (Figure 4). She was discharged home on low-molecular-weight heparin without complication.
在入院第63小时，患者在进行VA-ECMO时被带至心脏导管室进行经导管取栓术。PA血管造影显示左，右主PA远端有明显的闭塞性血栓负担，双侧下叶灌注受损（图3A）。基于大口径导管的机械装置可与血栓机械接合以进行手动抽吸（FlowTriever 系统；Inari Medical，Irvine，CA）用于进行右主PA和上肺动脉以及左远端主PA和叶间动脉的栓塞取出术。最终的PA血管造影显示双侧PA和肺野的灌注得到改善（图3D）。VA-ECMO在接下来的三天内撤机，并拔除了气管插管，并停用了血管加压药。她的心理状态处于基线状态。再次经胸超声心动图显示正常RV，左心室大小和功能，左心室射血分数为71％，RV收缩压为28 mm Hg（图4）。她使用低分子量肝素出院，无并发症。
Figure 3.Pulmonary artery (PA) angiography during catheter-based embolectomy.A, Initial bilateral PA angiography showing large occlusive thrombus burden in the distal right main PA, with impaired perfusion and distal blush in the right lower lobe. On the left, there is significant thrombus burden in the distal left main PA and interlobar artery with impaired perfusion to the left lower lobe. B, Selective right PA angiography showing improved perfusion in the right lower lobe after catheter-based embolectomy. C, Selective left PA angiography showing thrombus in the distal left main PA and interlobar artery before catheter-based embolectomy. D, Final bilateral PA angiography showing improved bilateral PA perfusion after catheter-based embolectomy, particularly within the lower lobes.
Figure 4.Transthoracic echocardiogram after catheter-based embolectomy.A, Parasternal short axis view at end-systole showing normal right ventricle size. B, Apical 4-chamber view at end-systole showing normal right ventricle size. In motion, right ventricle function normalized.
PE is a leading cause of maternal mortality in the United States, accounting for 9.0% of all pregnancy-related deaths. Pregnancy is a dynamic physiologic state in which both the cardiovascular and coagulation systems undergo significant adaptation.
The cardiovascular changes associated with pregnancy have important hemodynamic implications in PE. In the antepartum phase, cardiac output increases because of an expansion of circulating blood volume, a decrease in systemic vascular resistance, and a rise in the baseline heart rate. Intrapartum, sympathetic activation increases myocardial oxygen demand while repetitive Valsalva maneuvers simultaneously cause rapid transient decreases in cardiac preload. Immediately postpartum, autotransfusion and the release of mechanical pressure off of the venocaval system causes a sudden increase in cardiac preload. These collective physiologic changes serially increase RV workload. In the context of massive PE and elevated pulmonary vascular resistance, the sudden increase in cardiac preload may exacerbate pre-existing high RV stress, increasing the risk of acute RV failure and subsequent death.
Anticoagulation remains the cornerstone of treatment for all forms of PE. Available evidence for the advanced management of peripartum massive PE is derived largely from case studies of thrombolysis, which demonstrate maternal and fetal survival rates of 94% and 88%, respectively, at the cost of an increase in major bleeding.Given these data, along with the significant risks associated with surgical embolectomy, catheter-based embolectomy may be a reasonable first-line interventional therapy in this setting. VA-ECMO is an evolving therapeutic strategy for hemodynamic support in pregnancy and postpartum, although its effects on uterine circulation remain unknown.
We highlight a case of peripartum massive PE complicated by spontaneous labor, obstructive shock, and cardiac arrest. VA-ECMO as a bridge to catheter-based embolectomy may be a reasonable interventional strategy in this extremely high-risk clinical setting.