Successful use of extracorporeal cardiopulmonary membrane oxygenation in acute severe aortic regurgitation with cardiovascular collapse

Abstract

We report the case of a 55-year-old man who was transferred from an overseas institution with an initial impression of non-ST-elevation myocardial infarction (NSTEMI). Subsequent investigation found a severe aortic regurgitation (AR) complicated by acute ischemic hepatitis and acute renal injury, and the patient developed cardiopulmonary collapse with pulseless electrical activity perioperatively. Cardiopulmonary resuscitation was commenced immediately, venoarterial extracorporeal membrane oxygenation (ECMO) was immediately set up to bridge for emergency aortic-valve replacement surgery. The patient was subsequently weaned off ECMO and made a complete recovery. We demonstrate the successful use of ECMO for resuscitation in a patient with AR complicated by cardiovascular collapse.

Introduction

The use of an extracorporeal membrane oxygenation (ECMO) circuit is generally contraindicated in severe aortic regurgitation (AR). We present a case with atypical symptoms of acute severe AR complicated by acute ischemic hepatitis and acute renal injury, where ECMO is successfully used as part of the resuscitation efforts when the patient had a cardiovascular collapse with a pulseless electrical activity (PEA). The patient then underwent emergency aortic-valve replacement and made a complete recovery.

Case report

A 55-year-old Chinese male with a history of hypertension and dyslipidaemia presented to an overseas institution with recent chest pain, shortness of breath on exertion and epigastric discomfort for two weeks prior to the admission. The patient was hemodynamically stable upon physical examination, blood pressure 118/42 mmHg, heart rate 84 bpm, SpO₂ 100% on room air, no murmur recorded and there was no peripheral oedema. There was right hypochondrium and epigastric tenderness with hepatomegaly (3 cm below costal margin). An electrocardiogram showed Left bundle branch block (LBBB) and T-wave inversion inversion in V5/6 and elevated cardiac enzyme levels (CK 1043U/L, CKMB 11.6UG/L, Trop T 63NG/L). The initial impression was non-ST-elevation myocardial infarction (NSTEMI) and the patient was subsequently transferred to our hospital for further management. Further investigations revealed severe transaminitis (Alanine aminotransferase ALT 1780 to 3160 U/L, Aspartate transaminase AST 2403 to 5035 U/L) and markedly elevated serum creatinine. Chest X-ray showed very mild congestion.

A bedside 2D echocardiography found the patient to have severe AR, moderate mitral valve regurgitation, moderate tricuspid valve regurgitation and no vegetation was evident. The pulmonary artery systolic pressure was 39 mmHg and the left ventricular cavity size was normal with an ejection fraction of 60%–65%. A subsequent computed tomography (CT) aortogram did not show any dissection or aortic intramural hematoma.

The patient was scheduled for an urgent aortic-valve replacement. However, in view of the acute kidney injury and elevated liver enzymes, the issue of the acute nature of the AR was raised, and it was deemed that the patient’s condition could be optimised prior to surgery, and dialysis was initiated. However, the patient became progressively hypotensive and needed to be intubated and subsequently stabilised on inotropes. He was urgently transferred to the operating room for surgery. Prior to transfer to the operating table, he suffered PEA collapse. Immediate cardiopulmonary resuscitation (CPR) was commenced with intravenous adrenaline boluses. The decision was made to perform a venoarterial (VA) ECMO to establish flow while CPR was being performed.

ECMO was inserted via the right femoral artery and vein and 3.7L/min full flow was achieved. Meanwhile a 4-lumen central venous catheter (CVC) line was established via the right internal jugular vein and a right femoral intra-arterial line was placed. Once the surgical team was ready, sternotomy was made and the patient was then placed on cardiopulmonary bypass (CPB), and ECMO was discontinued. There was severe acute pulmonary oedema with large amounts of pink frothy fluid from the endotracheal tube. The patient received a total of 12 mg of adrenaline (bolus and infusion) and four direct current shocks for ventricular fibrillation before CPB.

The heart was found to be severely dilated and the aortic-valve leaflets were normal and no vegetation was evident. The aortic valve was replaced with a 23-mm Perimount Magna aortic valve. At the end of operation, the patient was weaned off CPB with inotropic support and remained on VA ECMO and transferred to the intensive care unit.

Continuous Renal Replacement Therapy (CRRT) was continued into the post-operative period. An immediate post-operative 2D echo showed poor ejection fraction, which improved by the fourth post-operative day. The patient was weaned off ECMO support by the third post-operative day and was on an intra-aortic balloon pump until a successful wean on the seventh post-operative day. The patient was then extubated and was neurologically intact. The patient remained well until discharge on the 14th post-operative day, with normalisation of the liver and renal function. Post-operative histology showed myxomatous degeneration and mild fibrosis in the aortic valve.

Discussion

AR is characterised by regurgitation of blood from the aorta to the left ventricle during diastole. The acute onset of severe AR is a medical emergency due to the inability of the left ventricle to quickly adapt to the rapid increase in end-diastolic volume caused by regurgitant blood.^1–3 If not surgically corrected, acute severe AR commonly results in profound hypotension and cardiogenic shock with acute pulmonary oedema.

However, acute severe AR may be difficult to recognise clinically due to the subtle examination findings, ² and the diagnosis can be missed initially, as seen in our patient. His presentation was mistaken for an acute coronary event and it was unusual that the patient remained relatively well compensated despite liver and renal dysfunction. The liver function test revealed markedly elevated AST and ALT, which was associated with low output status leading to hepatic hypoxia. Similarly, the marked increment in serum creatinine was also related to ischemic injury to the kidney. Once the insult had been corrected, there was a remarkable return of renal function to the baseline.

ECMO is an extracorporeal technique of providing prolonged cardiac and respiratory support to persons whose heart and lungs are unable to provide an adequate amount of gas exchange or perfusion to sustain life. The technology for ECMO is largely derived from CPB, which provides shorter-term support.^4,5 The most common cardiac indication for ECMO in adults is cardiogenic shock/severe cardiac failure due to almost any cause, including the inability to wean from a CPB circuit following cardiac surgery, a bridge to cardiac transplant or longer-term ventricular assist device support, post-heart-transplant primary graft failure, as well as periprocedural support for high-risk percutaneous cardiac interventions.^4,5

Currently, there is some evidence showing better hospital survival rates after receiving the extracorporeal CPR in cardiac arrest of cardiac origin. In a retrospectively analysis, for a total of 406 adult patients with witnessed in-hospital cardiac arrest receiving CPR for >10 min from January 2003 to June 2009, in the matched population, the survival discharge rate and six-month survival rates with minimal neurologic impairment in the extracorporeal CPR group were significantly higher than those in the conventional CPR group. ⁶ Chen et al. carried out a three-year prospective observational study for patients aged 18–75 years with witnessed in-hospital cardiac arrest; findings suggest that the 975 patients with in-hospital cardiac arrest events who underwent CPR for longer than 10 min, in both matched and unmatched patients who underwent extracorporeal CPR, had a higher survival rate to discharge and a better one-year survival than those who received conventional CPR. ⁷

The use of ECMO has been contraindicated for acute aortic insufficiency – the backward flow from severe regurgitation may cause left ventricle overloading. However, in our patient, due to the urgency of the situation, compared to CPB, ECMO was relatively easier to set up initially and less anticoagulant was required; we also thought VA ECMO was helpful for bridging to aortic-valve replacement. Although there was severe regurgitation, there was still some flow to the coronaries and brain in this cardiac arrest circumstance.

Conclusion

Our successful use of extracorporeal cardiopulmonary membrane oxygenation as part of the effort for CPR before acute aortic replacement showed that ECMO should still be considered for use in a cardiovascular collapsed patient with acute severe AR.