Use of Two Intracorporeal Ventricular Assist Devices As a Total Artificial Heart

Summary

Here, we present a protocol using two centrifugal pumps as a total artificial heart replacement.

Abstract

Mechanical circulatory support (MCS) has been introduced as a viable alternative to heart transplantation primarily through the use of intracorporeal ventricular assist devices (VADs) for support of the left ventricle. However, certain clinical scenarios warrant biventricular mechanical support. One strategy for some patients is the excision of both ventricles and the implantation of two VAD pumps as a total artificial heart (TAH). This has recently been made possible by the improvements in device design and the small profile of centrifugal devices. This TAH approach remains experimental with many important challenges such as the device settings to balance the right and left circulation, the orientation of the devices and the outflow graft with their influence on hemolysis and stability, and the outcome of chronic support using such an orientation. This protocol aims to provide a reproducible approach for total artificial heart replacement with two intracorporeal centrifugal VADs in a cow model.

Introduction

There has been growth in the number of patients with heart failure, with an estimated 5.7 million adults suffering from this condition in the United States today¹. Around 300,000 patients have end stage heart failure with a life expectancy of less than one year. While heart transplantation remains the gold standard therapy for end stage heart failure, it is greatly limited by the number of available donor organs. MCS has been introduced as a viable alternative to heart transplantation especially through the use of VADs². VADs work by unloading the left ventricle and providing forward flow (supported by a pump) directly i....

Protocol

Age-matched (for blood donation if needed) calves (weight 80–90 kg) are cared for in the animal facility. Housing and all treatment procedures are performed in accordance with the guidelines of the Animal Care and Use Committee of Duke University Medical Center.

1. Initiation of Anesthesia

1. After fasting for 8–12 h, pre-medicate the calf with Telazol (4.5 mg/kg/intramuscularly) and then administer isoflurane (1–4%) via a face mask.
2. Place the cow in a supine position on a heated table and intubate. Fix the extremities to the table using heavy ties.
3. Place an intravenous catheter (14–20 ga....

Results

Demonstrated in Figure 1 is the attachment of the sewing rings. Figure 1A shows the "bunching" of the ventricle tissue that may create a problem with pump attachment. Figure 1B represents the correct attachment.

Figure 2 and Figure 3 are two different orientations of the pumps. In .......

Discussion

In this manuscript, we describe the use of two centrifugal flow VADs as an intracorporeal TAH. This technique maybe very useful to study the effect of artificial circulation on secondary organs such as the lungs and liver. Furthermore, it may be useful for the study of the hemodynamic changes from different pump orientations and flow scenarios. The critical steps within this protocol involve how the sewing rings are attached to the ventricular tissue while also incorporating the valvular annuli for strength. It is crucia.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
SPO2  and heart rates are to be monitored: Multiparameter	Meditech Equipment, Co., Ltd.	MD-908	hemodynamic monitor intraoperatively
Viscot Mini XL Surgical Markers	Amazon	B007P550WG	marking sternum before incision
60W High Power Electric Pet Cat Rabbits Horse Animal Hair Cutting Clipper	LILY International Business CO., LIMITED	ZP-293	Fur shaving
No. 10 scalpel blade	Swann-Mortan, England	301	Skin incision
Matzenbaum scissor	BD-V. Mueller, USA	CH2006-001	Vascular exploration
Scissors	Felco, USA	FELCO 200A-50, Felco Professional Bypass Lopper	For sternotomy
A self-retractor	BD-V. Mueller, USA	AU19270	SCHUKNECHT Self-Retaining Postauricular Retractor,
Sternal retractor	BD-V. Mueller, USA	CH6950-007	Cooley sternal retractor
Pressure transducer (Millar Mikro-Tip, 5Fr)	Millar, USA	MillarMikro-Tip, SPR-350S	Assessment for pulmonary artery or venous pressure
AD instruments (PowerLab)	AD instruments, USA	PowerLab 16/35	Pressure signal transduction
Umbilical tapes	Medline industries Inc., USA	U11	For isolation and snaring of superior or inferior vena cava
Vessel loops	Aspen Surgical, USA	3901, 3902 and 3904	Isolation of vessels
Silk sutures, 2-0	Ethicon US, LLC, USA	SA11G	For snare of superior or inferior vena cava
Ticron 2-0	Covidien, USA	TicronTM suture	Vascular suture
Prolene, 7-0	Covidien, USA	Surgipro II	Vascular suture
Prolene, 6-0	Covidien, USA	Surgipro II	Vascular suture
Prolene, 4-0	Covidien, USA	Surgipro II	Vascular suture
Prolene, 3-0	Covidien, USA	Surgipro II	Vascular suture
Aortic cannula, 15-18 Fr	Medtronic, USA	Elongated-One-Piece-Arterial cannula 3D	Aortic cannula for setting of cardiopulmonary bypass
Venous cannula, 28Fr	Edwards Lifesciences	single stage	Venous cannula for setting of cardiopulmonary bypass