2023 SCAI SHOCK

Recognizing Left Ventricular Distension: A Case of Low-Flow VA-ECMO as a Bridge-to-Transplant in a Patient with Significant Aortic Regurgitation

Presenter

Andrew H. Nguyen, DO, Inova Heart and Vascular Institute, Fairfax, VA
Andrew H. Nguyen, DO1, Thomas I Minik, DO1, Mohamud Mohamud, MD1, Mariyam Sheidu, MD2 and Shashank Sinha, MD, MSc3, (1)Inova Heart and Vascular Institute, Fairfax, VA, (2)Inova Heart and Vascular Institute, Falls Church, VA, (3)Inova Health System, Falls Church, VA

Title

Recognizing Left Ventricular Distension: A Case of Low-Flow VA-ECMO as a Bridge-to-Transplant in a Patient with Significant Aortic Regurgitation

Introduction

Veno-arterial extracorporeal membrane oxygenation (VA-ECMO) is a form of mechanical circulatory support (MCS) utilized in patients requiring significant biventricular support presenting with refractory cardiogenic shock (CS). Severe aortic regurgitation (AR) is traditionally a contraindication for VA-ECMO given concern for progressive left ventricular (LV) distension, pulmonary edema, and elevated thrombotic risk. We present a case of a patient with refractory CS and severe AR who underwent low-flow VA-ECMO as a bridge-to-transplant successfully. We also discuss the clinical markers to recognize significant LV distension.

Clinical Case

A 72-year-old male with long-standing nonischemic cardiomyopathy presented to our center for second opinion regarding his end-stage heart failure (HF). The patient had frequent hospitalizations for decompensated HF in which he was most recently discharged home with inotropic support. He continued to deteriorate, however, now with dyspnea at rest, severe fatigue, and volume overload. RHC prompting his admission confirmed severely elevated bi-ventricular filling pressures and reduced cardiac indices indicative of refractory CS. Transthoracic echocardiogram (TTE) demonstrated severely decreased bi-ventricular function, an LVEF of 9%, and severe AR. The patient was listed for orthotopic heart transplant (OHT) following presentation at a multidisciplinary transplant meeting. Temporizing measures including pulmonary artery-guided hemodynamic management with aggressive diuretic therapy unfortunately did not improve his condition. Further escalation of inotropic therapy was limited due to development of atrial tachyarrhythmias. Additionally, initiation of vasopressor therapy was required as signs of inadequate perfusion became apparent. MCS strategies including intra-aortic balloon pump (IABP), Impella, left ventricular assist device (LVAD), and VA-ECMO were discussed though concerns of his candidacy were raised given findings of severe AR. Ultimately, the decision was made to initiate VA-ECMO as a bridge-to-transplant with close monitoring for LV distension and fixed low-flow rate of no more than 3L/min until a suitable donor was identified. Two days after VA-ECMO initiation, the patient underwent OHT without complication.

Discussion

An effective bridge-to-transplant strategy for patients with severe AR remains a significant challenge. Traditionally, severe AR is a contraindication for initiation of VA-ECMO due to lack of an effective LV venting strategy (e.g., simultaneous Impella or IABP implementation) to reduce LV filling pressures, posing a risk of impaired LV performance leading to progressive LV distension, pulmonary edema, and thrombosis. Thus, in our patient without a viable LV venting strategy, adhering to a fixed low-flow pump rate and close monitoring for signs of LV distension was crucial. Reduced arterial pulsatility, for example, is often identified by a pulse pressure of <10 mmHg and is one of the earliest signs of LV distension. Furthermore, absence of the dicrotic notch on arterial waveforms reflect failure of aortic valve (AV) opening, suggestive of LV distension. Lastly, progressive increase in pulmonary artery and capillary wedge pressures may be observed in LV distension. These findings should prompt urgent investigation with TTE, where typical findings of LV distension include elevated LV end-diastolic diameter, LV thrombus, an increased E/e’ ratio, and intermittent or absent opening of the AV.