Ventricular assist device implantation in a patient with systemic right ventricle and pectus excavatum

Systemic right ventricular failure is a common finding in patients with transposition of the great arteries. Some of these patients require ventricular assist device implantation. We describe the feasibility of HeartMate 3 [Abbott, Illinois, United States] implantation in a patient with transposition of the great arteries, high human leukocyte antigen sensitization, and severe pectus excavatum using a two-stage approach. Learning objectives 1. To notice the challenges faced while implanting HeartMate 3 [Abbott, Illinois, United States] in patients with congenital heart disease and anatomical limitations.2. To understand that despite the difficulties, HeartMate 3 implantation is possible, worthwhile, and sometimes the only choice in a patient with end-stage heart failure and congenital heart disease.


Introduction
Patients with a systemic right ventricle, such as transposition of the great arteries (TGA) after Mustard correction, can experience advanced heart failure, eventually requiring heart transplantation [1]. Heart transplantation is not always an option due to the shortage of donor hearts, anatomical considerations, human leukocyte antigen (HLA) sensitization, and comorbidities. In particular, patients with (surgically corrected) congenital heart disease, who have had multiple operations in childhood, have a higher risk of unfavorable cardiac anatomy, as well as the risk of HLA sensitization [2]. Some of these patients may be suitable for ventricular assist device implantation, either as bridge to transplant or destination therapy (DT) [1].

Case report
A 43-year-old Caucasian woman with history of TGA and Mustard procedure was referred to our heart transplant center for a second opinion because of progressive dyspnea and exercise intolerance as a result of end-stage heart failure. On physical examination, she had normal body mass index of 24.9 kg/m 2 , blood pressure of 105/61 mmHg, and normal temperature and respiratory rate. There were no significant murmurs, no leg edema, and normal breathing sounds. Her thorax was deformed by a severe pectus excavatum. Her past medical history is summarized in the timeline (Table 1).

Investigations
Initial echocardiography showed a dilated systemic right ventricle with severe impairment. There was severe systemic atrioventricular (tricuspid) valve insufficiency, with a vena contracta of 10 mm. We could find no evidence of residual baffle obstruction (Videos 1, 2).
On laboratory examination, she had a creatinine of 1.07 mg/dL (95 μmol/L), potassium of 3.5 mmol/L, and sodium of 137 mmol/L. The high-sensitivity C-reactive protein level was 8 mg/l and the Nterminal pro-B-type natriuretic peptide level was 5309 ng/L.
The electrocardiogram showed an AV-paced rhythm with wide QRS complexes with right bundle branch block and left anterior fascicular block with an extreme axis.
Initially, right heart catheterization showed severe combined preand post-capillary pulmonary hypertension, with low cardiac output based on a pulmonary capillary wedge pressure (PCWP) 26 mmHg, mean pulmonary artery pressure (mPAP) 54 mmHg, right atrial pressure (RAP) 18 mmHg and cardiac index (CI) 1.6 L/min/m 2 . Reversibility testing did reduce pulmonary vascular resistance (PVR) but increased the filling pressures, suggestive of severe systemic AV valve insufficiency in combination with ventricular failure.
After intensification of high-dose loop diuretic therapy (bumetanide 10 mg/24 h) and treatment with dobutamine, a right heart catheterization was repeated which showed marked improvement (PCWP 13, mPAP 26 mmHg, RAP 8 mmHg, CI 3.1 L/min/m 2 ), but after downtitrating of inotropes and intravenous diuretics, hemodynamics and renal function worsened. Computed tomography (CT) scan for determination of vascular access and extent of pectus excavatum showed absence of important collaterals, normal abdominal, and femoral access, and the known cardiac condition. Based on a Haller index of 3.5 ( Fig. 1A-C), the pectus excavatum was considered severe [3], with also rotation of the sternum. Renewed HLA investigation showed a high degree of panel-reactive antibody (>75%, most conservative 84%, DR1, DR4, DQ7, DQ8, DQ10).

Decision making
The patient was discussed in our advanced heart failure team and given the unfavorable anatomy, high degree of HLA sensitization, and severe pulmonary hypertension declined for heart transplantation at our center. She was accepted for ventricular assist device (VAD) placement in the systemic right ventricle as Destination Therapy (DT), together with minimal surgical correction of pectus excavatum to allow anastomosis of the outflow graft to the ascending aorta.

Procedure
Before VAD placement, the patient was placed on cardiopulmonary bypass using a femoral approach for both arterial and venous access. To get access the distal sternum was mobilized by removing the cartilage and by transection below the manubrium followed by adhesiolysis of the heart, which was extremely displaced to the left thoracal cavity. Then the position for the inflow cannula in the systemic right ventricle was determined by visual inspection and transesophageal (TEE) assessment.
The most optimal position for the HeartMate 3 [Abbott, Illinois, United States] motor casing in the thorax was determined to be at the transition from the margo acutus to the right ventricular anterior wall. Some right ventricular trabeculae needed to be resected for optimal placement of the inflow cannula. The HeartMate 3 was also somewhat tilted by using asymmetric felt placement for a good position of the inflow cannula in regard to the interventricular septum and tricuspid valve. This was checked by TEE (Videos 3, 4).
After 4 days (time taken to evaluate possible bleeding risk and need for reoperation) the pectus excavatum was partially corrected (cranial part) and the wound closed.

Postoperative period
The early postoperative period was uneventful besides atrial tachycardias (for which cardioversion was carried out) and delirium. The CT scan of the patient is shown in panels D and E of Fig. 1. The patient was discharged from the intensive care to the coronary care unit on day 7, discharged to the ward on day 15, and to the rehabilitation facility on day 26.
The later inpatient postoperative period was remarkably stable, with normalized renal function. Initial VAD speed was set at 4800 rpm, and increased to 5000 rpm at day 1, and subsequently to 5200 rpm at day 8. This resulted in a pump flow of around 4.3 L/min. Transthoracic echocardiography showed normal pulmonary (left) ventricular function, a systemic (right) ventricular function that remained poor (Video 5) with also severe systemic AV valve insufficiency remaining. The inflow cannula was visible in the lateral free wall of the right ventricle, with unobstructed flow visible into the inflow cannula.

Follow-up
Her exercise tolerance slowly increased in the first year after VAD placement. She feels comfortable at rest and mild to moderate exercise, can ride a bike and she has not been readmitted since discharge from the rehabilitation center. She has had no major adverse events since VAD implantation.

Discussion
The management of heart failure due to failure of systemic right ventricles is complex. Heart transplantation and VAD implantation are challenging because of anatomical variations of the heart and great vessels, and HLA sensitization is frequent, limiting heart transplantation in these patients. We report the feasibility and safety of LVAD   HeartMate 3 implantation for a patient with high HLA sensitization and pectus excavatum.
There have been limited reports on the implantation of VADs in systemic right ventricles, either in TGA or CCTGA, and both as a bridge to transplant or destination therapy [1,[4][5][6][7]. Regarding the type of VAD, less is known on the use of HeartMate 3 in such patients. We do know that the motor housing dimensions are slightly greater as compared with the Heartware HVAD [Medtronic, United States] (now discontinued), making positioning below the sternum somewhat more challenging.
The implantation procedure and the type of VAD are important factors for successful mechanical support in patients with systemic right ventricular failure. Other studies reporting the use of HeartMate 3 in TGA patients are summarized in Table 2 [1,[4][5][6].
The patient described in this case report had a severe pectus excavatum, which further compromised the available space for the motor housing of the HeartMate 3. We used pre-operative CT scanning to determine if there was enough space for VAD implantation and opted for a two-stage approach where at first a) the VAD was implanted in the systemic right ventricle and b) after 4 days (after stabilization and making sure no bleeding complications developed) a partial pectus correction (cranial part of the sternum) was carried out. To our knowledge, our case is the first report on the use of the HeartMate 3 in a patient with TGA and limited anatomical space due to pectus excavatum.

Conclusions
This case showed that implantation of a VAD (HeartMate 3) is possible in patients with complex congenital anatomy, complicated by limited intrathoracic space due to pectus excavatum.

Declaration of competing interest
None.