Decellularized aortic homografts for aortic valve and aorta ascendens replacement

Abstract

Objectives: The choice of valve prosthesis for aortic valve replacement (AVR) in young patients is challenging. Decellularized pulmonary homografts (DPHs) have shown excellent results in pulmonary position. Here, we report our early clinical results using decellularized aortic valve homografts (DAHs) for AVR in children and mainly young adults.

Methods: This prospective observational study included all 69 patients (44 males) operated from February 2008 to September 2015, with a mean age of 19.7 ± 14.6 years (range 0.2-65.3 years). In 18 patients, a long DAH was used for simultaneous replacement of a dilated ascending aorta as an extended aortic root replacement (EARR). Four patients received simultaneous pulmonary valve replacement with DPH.

Results: Thirty-nine patients (57%) had a total of 62 previous operations. The mean aortic cross-clamp time in isolated cases was 129 ± 41 min. There was 1 conduit-unrelated death. The mean DAH diameter was 22.4 ± 3.7 mm (range, 10-29 mm), the average peak gradient was 14 ± 15 mmHg and the mean aortic regurgitation grade (0.5 = trace, 1 = mild) was 0.6 ± 0.5. The mean effective orifice area (EOA) of 25 mm diameter DAH was 3.07 ± 0.7 cm(2). DAH annulus z-values were 1.1 ± 1.1 at implantation and 0.7 ± 1.3 at the last follow-up. The last mean left ventricle ejection fraction and left ventricle end diastolic volume index was 63 ± 7% and 78 ± 16 ml/m(2) body surface area, respectively. To date, no dilatation has been observed at any level of the graft during follow-up; however, the observational time is short (140.4 years in total, mean 2.0 ± 1.8 years, maximum 7.6 years). One small DAH (10 mm at implantation) had to be explanted due to subvalvular stenosis and developing regurgitation after 4.5 years and was replaced with a 17 mm DAH without complication. No calcification of the explanted graft was noticed intraoperatively and after histological analysis, which revealed extensive recellularization without inflammation.

Conclusions: DAHs withstand systemic circulation, provide outstanding EOA and appear as an alternative to conventional grafts for AVR in young patients. EARR using DAH is a further option in aortic valve disease associated with aorta ascendens dilatation as it avoids the use of any prosthetic material.

Keywords: Aortic valve; Decellularized homografts; Valve prosthesis; Valve replacement.

Figure 1:

Echocardiographic mean gradient over time in the DAH. Different colours represent different patients; loess-smoothed lines are interpolated between the measurements for each individual. Some individuals show gradients that decrease over time.

Figure 2:

Valvular regurgitation over time in DAH (0 = none, 0.5 = trace, 1 = mild, 1.5 = mild to moderate, 2 = moderate, 2.5 = moderate to severe and 3 = severe). This figure shows the individual aortic valve insufficiency development and loess-smoothed interpolation lines. The decrease of insufficiency is not uncommon.

Figure 3:

Freedom from explantation including the percentage of conduits with degeneration signs for the DAH (peak gradient >49 mmHg and/or at least moderate regurgitation). For 3 Moldavian patients, only clinical follow-up was available.

Figure 4:

z-Value development of DAH annulus size for subgroups over time. Black lines delineate patients younger than 10 years with a DAH smaller than 15 mm at implantation, green—patients younger than 10 years with a DAH bigger than 15 mm and red—patients older than 10 years. z-Value development of DAH annulus size over time. Package labelled annulus diameter was rounded to z-value integers, and each postoperative measurement is again expressed as a z-value according to the actual height and weight of the patient. A loess fit curve was then drawn for each implant size group. The green area shows the normal range in the middle of which the lines should converge.

Figure 5:

(A) Preoperative echocardiography demonstration subvalvular stenosis and sufficient annulus size; (B) intraoperative aspect of the DAH before explantation (explantation performed after completion of the patients enrolment in the study); (C) postoperative echocardiography after implantation of a 17-mm DAH and resection of subvalvular stenosis; (D) HE staining of the non-coronary cusp; (E) Pentachrom staining of the non-coronary cusp; (F) Van Kossa staining of the non-coronary cusp; (G) HE staining of the non-coronary sinus; (H) Pentachrom staining of the non-coronary sinus; (I) Van Kossa staining of the non-coronary sinus.

Figure 6:

Preoperative aspects of the severely calcified and stenotic conventional pulmonary homograft and calcified dilated aortic bulbus in a Ross patient are shown in the first row. The second row shows the intraoperative aspect after double valve replacement with decellularized homografts including EARR by a long DAH and CMR images after 14 months.