Bedside Echo-Guided Implantation of MoyoAssist® as a Bridge to Heart Transplantation

A multidisciplinary team at Southern Medical University Southern Hospital successfully applied the MoyoAssist® extracorporeal ventricular assist device (VAD) as a bridge to heart transplantation in a critically ill patient with end-stage heart failure. The procedure was performed at the bedside under transesophageal echocardiography (TEE) guidance, ensuring hemodynamic stability without the risks associated with patient transfer.

The case highlights the role of MoyoAssist® in providing temporary circulatory support and demonstrates the value of coordinated, multidisciplinary management in complex cardiovascular disease.

Patient Profile

• Age: 27, male

• Medical history: Hypertension, hyperuricemia, and Post ventricular septal defect repair, right ventricular outflow tract reconstruction, and mechanical aortic valve replacement.

• Condition: Post-valve replacement, left ventricular ejection fraction (LVEF) remained <20%. On postoperative day 10, the patient developed ventricular fibrillation and required intensive care with mechanical ventilation and IABP support.

• Assessment: Echocardiography showed normal prosthetic valve function but severely impaired ventricular function (LVEF 13%).The cardiac function was irreversible, thus surgeons decided to do the heart transplantation for heart transplantation.

Ultrasound Diagnosis:

Status post ventricular septal defect repair, right ventricular outflow tract, and aortic mechanical valve replacement:

1. Aortic prosthetic mechanical valve function normal with moderate orifice regurgitation; follow-up recommended.

2. Increased forward flow velocity at distal right ventricular outflow tract-pulmonary valve orifice.

3. Mild mitral and tricuspid regurgitation.

4. Left ventricular enlargement, left atrial slight enlargement.

5. Small pericardial effusion.

6. Significantly reduced LVEF.

Key Findings

• After aortic valve replacement, the patient’s left ventricular ejection fraction (LVEF) remained critically low (<20%).

• On postoperative day 10, he developed ventricular fibrillation and required intensive care with mechanical ventilation and intra-aortic balloon pump (IABP) support.

• Echocardiography confirmed normal prosthetic valve function but a severely reduced LVEF of 13%.

• The left ventricular dysfunction was considered irreversible, establishing the indication for heart transplantation.

• Conventional support with IABP was inadequate, while extracorporeal membrane oxygenation (ECMO) carried the risk of increased left ventricular afterload.

Diagnoses

• Pre-operative aortic insufficiency and ventricular septal defect

• End-stage heart failure following valve replacement with irreversible LV dysfunction (LVEF 13%)

• Recurrent ventricular fibrillation (“electrical storm”)

Procedure Strategy

To bridge the patient to transplantation, the team elected to implant a temporary extracorporeal left ventricular assist device (MoyoAssist® Extra VAD). To minimize the risk of deterioration during transport, the device was implanted at the bedside in the intensive care unit under transesophageal echocardiography (TEE) guidance. A drainage circuit was established by placing a 21Fr venous cannula into the left atrium via the right femoral vein after transseptal puncture. Following removal of the IABP catheter, a 17Fr arterial cannula was inserted into the right femoral artery to complete the perfusion circuit. The device was initiated at a flow of 3 L/min, achieving stable hemodynamics.

Jul 21st BNP/NT-proBNP

Aug 2nd BNP/NT-proBNP

Echocardiogram result on the 6th day of assistance

Ultrasound Diagnosis:

Status post ventricular septal defect repair, right ventricular outflow tract (dilatation), mechanical aortic valve replacement, and left ventricular assist device implantation:

1. Normal function of prosthetic mechanical aortic valve with moderate regurgitation

2. Mild mitral and tricuspid regurgitation

3. Increased forward flow velocity in pulmonary valve and main pulmonary artery (recommend follow-up)

4. Left ventricular enlargement

5. Small pericardial effusion

Echocardiogram result on the 13th day of assistance

Ultrasound Diagnosis:

1. Status post ventricular septal defect repair, right ventricular outflow tract dilatation, aortic valve mechanical replacement + left ventricular assist device implantation

2. Aortic prosthetic mechanical valve function normal with mild-moderate valvular regurgitation

3. Mitral and tricuspid regurgitation (mild)

4. Left ventricular enlargement; left ventricular wall hypokinesis

5. Pericardial effusion (small amount)

6. Significantly reduced LVEF

7. Note: Left pleural effusion

Echocardiogram on the 8th day after heart transplantation

Ultrasound Diagnosis:

1. Post-cardiac transplantation:

2. Slight thickening of interventricular septum and left ventricular posterior wall

3. Tricuspid regurgitation (mild)

4. Normal LVEF

Postoperative Course

The Extra VAD provided circulatory support for 14 days. The patient was extubated on Day 7. After a suitable donor heart became available, the patient underwent successful heart transplantation, during which the device was explanted. Post-transplant recovery was stable, with discontinuation of vasoactive medications and removal of invasive lines prior to transfer to the general ward.

Clinical Insights

The Extra VAD played a pivotal role as a bridge to transplantation by providing reliable circulatory support. Bedside implantation under TEE guidance reduced the risk associated with transporting a critically ill patient. The case highlights the value of a coordinated, multidisciplinary approach in managing advanced heart failure and supports the role of MoyoAssist® as a technical option for individualized treatment strategies in end-stage disease.