Veno-arterial mechanical support as bridge to surgery in a patient with severe aortic regurgitation: a case report

Introduction

Veno-arterial extracorporeal membrane oxygenation (VA-ECMO) is a technique indicated for patients, with reversible disease or a treatable condition, in cardiogenic shock despite adequate intravascular volume and inotropic support. Presence of aortic regurgitation is commonly considered as a contraindication for ECMO because of the risk of serious left ventricular distension due to retrograde flow without aortic valve competence. ¹

In this case report, we describe the use of ECMO in a young patient referred to our centre when in profound cardiac failure and dysfunctioning mechanical aortic valve.

Case report

A 38-year-old female patient admitted to the emergency department of her local hospital during the night due to increasing shortness of breath (SOB) and symptoms of cardiac failure in the few days preceding the admittance. Five years before she had a mechanical valve replacement plus a separate interposition graft for ascending aorta replacement secondary to bicuspid valvulopathy and ascending aorta enlargement. Furthermore, she previously had two ischemic strokes without residual neurological signs. Anticoagulant therapy was stopped recently for unknown reasons. After arrival in the emergency department she was intubated, and inotropes were commenced to sustain her cardiovascularly. Systemic pressure 70/40 mmHg despite high doses of inotropes and vasoconstrictors (epinephrine, norepinephrine and vasopressin), tachycardic, mottled and cold peripherally. A transthoracic echocardiography was then performed showing severely reduced left ventricular function. ECMO retrieval team from the Royal Brompton Hospital in London was then contacted.

At the arrival of the ECMO team (around 45 minutes afterward), the patient was still haemodynamically unstable with high doses of inotropes and vasoconstrictors, increased lactate (12 mmol.L-1 rising) and reduced SvO2 (<50%). A new transthoracic echocardiogram (no transoesophageal echocardiography (TOE) available) was repeated which confirmed a severely reduced left ventricular (LV) ejection fraction around 10/15%, severe aortic regurgitation, moderate mitral regurgitation, no tricuspid regurgitation and normal right ventricular function. Abnormal movement of the aortic mechanical leaflets was detected.

Risks and benefits of commencing extracorporeal circulation in a patient with severe aortic regurgitation were then discussed within the team, and the family was involved in the discussion. Due to young age and possible correctable cause of acute cardiac failure, the decision was taken to support the circulation with VA-ECMO.

Bedside percutaneous cannulation was achieved via an aseptic procedure. Ultrasound-guided puncture of the right femoral vein and the left common femoral artery were achieved using the Seldinger technique and sequential dilation of both vessels. Seventeen French single-stage cannula (Medtronic®, Minneapolis, USA) was positioned in the iliac artery as return cannula, and 25 French multistage (Medtronic®) as access cannula into the right atrium. A distal leg perfusion cannula was not placed at this stage as it is our current practice to place this later in our hospital. VA-ECMO was commenced using a Cardiohelp machine (Maquet®, Getinge Group, Rastatt, Germany) with blood flows of 4.9 L.min-1

The patient was stabilized with reduction of inotropic support and lactate (stable at 12 mmol/L after cannulation, 8.8 mmol/L 2 hours after ECMO commencement). Mean arterial pressure (MAP) >60 was maintained during the transfer to the tertiary referral cardiac centre for ongoing care.

On arrival TOE revealed severe aortic regurgitation with lack of movement of the mechanical valve leaflets (Figure 1). The left ventricle was 52 mm in size with moderate to severely impaired function and severe mitral regurgitation. Decision was made to perform urgent reoperation on the aortic valve. She was transferred to the operating room, and median sternotomy was performed. Cannulation was changed to central aortic and right atrial/inferior vena cava, and cardiopulmonary bypass was commenced. The aortic valve was inspected and found to be defective with pannus obstructing the normal function causing fixed opening of both leaflets (Figure 2). The valve was replaced with a bioprosthetic valve (Magna Ease size 21 mm; Edwars Lifescience®, Irvine, CA, USA). An attempt was made to come off bypass. This was impossible due to poor ventricular contractility and high ventilatory pressures. Aortofemoral VA-ECMO was then instituted, and the patient was transferred back to the intensive care unit in a stable condition. A femoral embolectomy was performed as the right leg was dusky and showing signs of ischaemia, with resolution of signs and clinical improvement afterwards.

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Figure 1.

Transoesophageal echocardiography (mid-oesophageal long axis view) showing abnormal aortic valve (mechanical) opening.

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Figure 2.

Intraoperative (anaesthetic view): aortic mechanical valve blocked by a mass.

The VA-ECMO blood flow was weaned slowly and progressively with TOE guidance and removed 5 days later without complications, with improvement in ventricular function (ejection fraction 45%) on low-dose epinephrine infusion (0.05 mcg.kg-1.min-1). The post-operative recovery was complicated by need for surgical evacuation of a post-operative pericardial effusion, acute kidney injury requiring renal replacement therapy and prolonged mechanical ventilation, with a percutaneous tracheostomy performed to facilitate weaning. The patient was treated with teicoplanin, rifampicin and gentamicin for 6 weeks, but no positive cultures were isolated. Three weeks after admission, tracheostomy was removed and she was discharged from intensive care. Eleven days later she was discharged from the hospital to a local hospital for physical rehabilitation.

Discussion

This case report describes the successful application of circulatory support of a patient in cardiogenic shock with severe aortic regurgitation using ECMO.

A case report by Sidebotham et al. ² described the unsuccessful use of VA-ECMO in a patient presenting with myocarditis and mild aortic regurgitation. After ECMO commencement, the regurgitation worsened and the patient presented signs of pulmonary oedema and acute left ventricular thrombus. The mechanics of left ventricular distension associated with ECMO in aortic regurgitation is known and has been considered as a contraindication to veno-arterial mechanical support. ³ Pappalardo et al. ⁴ studied the haemodynamic effects of ECMO on high-risk patients undergoing elective institution of ECMO as support for elective procedures (high-risk ventricular ablations or transcatheter aortic valve implantation (TAVI)). The main finding of the study was that, in the presence of moderate aortic regurgitation (AR), VA-ECMO was not able to effectively unload the LV. Despite this, VA-ECMO did provide effective circulatory support with acceptable MAPs and markers of end-organ perfusion.

ECMO can be used successfully in patients undergoing TAVI as a prophylactic or rescue manoeuvre. ⁵ During this procedure there is often a short phase of severe aortic regurgitation which was well tolerated in this group of patients.

As stated by Mulaikal et al., ⁶ the technological advances reached by extracorporeal techniques are giving to clinicians the possibility to push forward the boundaries enlarging the indications to this type of assistance.

Despite concerns about the consequences of potential exacerbation of ventricular distension and loading, our patient underwent surgical repair of the aortic valve and went on to make a full recovery with reversal of end-organ dysfunction and return to normal function of the left ventricle. Undoubtedly, the reason for success was the short duration of VA-ECMO, in so much that there was insufficient time for complications relating to ventricular distension to manifest.

Conclusion

This case report describes our experience of a patient where the use of VA-ECMO in a patient with severe aortic regurgitation did not lead to complications when operated on in the acute phase.

This shows that the presence of aortic regurgitation may not necessarily be an absolute contraindication for VA-ECMO which may be feasible and indeed life-saving as a rescue therapy in patients with aortic regurgitation and as a bridge to decision making or further treatment as long as there is a plan for expedient surgical plans for venting or intervention on the incompetent aortic valve.