Implantation of a Berlin Heart EXCOR

A previously healthy two-month-old infant born at thirty-six weeks presented with increasing fussiness, a respiratory rate of sixty breaths per minute and an oxygen saturation of 85 percent. A chest X-ray revealed significant cardiomegaly. A transthoracic echocardiogram demonstrated a severely dilated left ventricle with an ejection fraction of 26 percent. The patient’s hemodynamic stability was supported by milrinone at 0.5 mcg/kg/min and epinephrine at 0.04 mcg/kg/min. Because of her diagnosis of cardiomyopathy and critical status, the surgical team decided to proceed with operative implantation of the Berlin Heart EXCOR.

The Surgery

First, a midline sternotomy was performed. Aortic cannulation was conducted high on the patient's left lateral aortic arch to ensure enough space for future placement of the inflow cannula. The team commenced cardiopulmonary bypass, and the patient remained warm throughout the procedure. 

Next, the cardiac mass was elevated out of the pericardial well, and a single 5-0 polypropylene stitch was placed in the right ventricle to facilitate exposure. A pen was used to mark the site for the proposed cannula in the cardiac apex followed by identification of the left obtuse marginal and left anterior descending coronary arteries. A 2-0 silk suture was placed in the cardiac apex to serve as a retraction suture for ventriculotomy. An 11-blade scalpel was then used to make a ventriculotomy and all obstructing muscle below was excised. The inflow cannula was anchored with two pledgets at the nine o’clock and three o’clock positions. The remainder of the graft was sewn counterclockwise with 4-0 polypropylene in a running fashion between the pledgets. The inflow tunnel site was created superior to the rectus muscle, and the inflow cannula was brought through the tunnel.

Attention was then turned to the outflow cannula anastomosis. An 8-French Hemashield (collagen impregnated polyester) graft was connected to the Berlin cannula and tied with 2-0 silk ligature twice. An angled c-clamp was positioned on the right lateral anterior wall of the ascending aorta. An aortotomy was then created. The anastomosis of the graft to the aorta was performed using 5-0 polypropylene in a running continuous fashion. Similar tunneling was carried out to externalize the outflow cannula.

The cannulae were then deaired and connected to the pneumatic pump. A needle was inserted into the pump to withdraw remaining air. The pump chamber and valves were inspected for air bubbles, and none were found. The team then began to step up the pneumatic flow to thirty beats per minute. As the LVAD rate was increased, flow rates on the cardiopulmonary bypass machine were decreased. Deairing was continued through the needle in the pump until no air was present on the transesophageal echo. 

The patient successfully came off cardiopulmonary bypass with stable hemodynamics. Evaluation of the Berlin Ikus showed a well-functioning ventricular assist device. The total pump time was 59 minutes. Intraoperative TEE demonstrated a well-positioned apical inflow cannula in the LV apex with adequate decompression of the LV. There was no aortic insufficiency and good RV function.

Bivalirudin was started forty-eight hours postoperatively. Institutional protocol aims for a goal PTT of seventy to ninety seconds and to titrate the dose of bivalirudin accordingly. The patient’s dose ranged from 0.48-0.77 mg/kg/hr. The patient was extubated on postoperative day fourteen. She remains in the CVICU and is currently listed as status 1A for a heart transplant.

References

1. Zafar F, Conway J, Bleiweis MS, et al. Berlin Heart EXCOR and ACTION Post-approval Surveillance Study Report. J Heart Lung Transplant. 2021;40(4):251-259.
2. Bigdeli AK, Michel S, Kaczmarek I, et al. Modified Implantation Technique for the Berlin Heart EXCOR Assist Device in Adults. Artificial Organs. 2012;36: E48-E52.
3. Goswami D, DiGiusto M, Wadia R, et al. The Use of Bivalirudin in Pediatric Cardiac Surgery and in the Interventional Cardiology Suite. J Cardiothorac Vasc Anesth. 2020;34(8):2215-2223.

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