**4. Aortic valve abnormalities**

Only a small number of heart transplants with concomitant aortic valve replacement for moderate-to-severe aortic insufficiency or aortic stenosis have been documented [6, 7, 9, 10, 12, 15]. It has been reported [7] that a bioprosthetic valve is preferred on a predicted average donor heart survival of 10–15 years [2] and the relatively frequent need for endocardial biopsies early after transplantation. The need for warfarin after mechanical valve replacement could lead to frequent bridging and interruption of anticoagulation during scheduled endocardial biopsies. In addition, it was considered that a large bioprosthesis would likely outlast the life of the allograft. When the donor has a bicuspid valve, the donor's aorta carries an increased risk of expansion due to the inherent nature of the bicuspid aortic valve. In younger individuals with normal life expectancy, aortic valve repair may be an excellent alternative since the risk of structural valve deterioration of aortic bioprosthesis is known to be higher in younger patients. Rates of reoperation as high as 50% in 15 years have been reported in 25-year-old patients [19].

If aortic valve replacement is considered for a donor heart, careful evaluation of LVH status and expected ischemic time is mandatory. This is because significant LVH and prolonged ischemic time has been proven to jeopardize transplant outcomes.

The use of donor hearts with LVH has yielded mixed results in terms of recipient outcomes. Kuppahally et al. [20] reported that recipients of donor hearts with LVH (≥ 1.2 cm) had worse survival and a higher incidence of cardiac allograft vasculopathy (CAV). Subsequently, Pinzon et al. [21] reviewed the UNOS database between 2006 and 2010 with almost 3000 recipients and stratified donor hearts into groups without LVH (< 1.1 cm), with mild LVH (1.1–1.3 cm), and with moderate-severe LVH (≥ 1.4 cm). They found similar 30-day and 1-year survival rates across the recipients in all three groups. However, hearts from donors with additional risk factors such as older age or prolonged cold ischemic time (≥4 h) exhibited worse survival [21], suggesting an association between LVH and other donor risk factors. The 2010 ISHLT guidelines for the care of heart transplant recipients state that using donor hearts with LVH (wall thickness < 1.4 cm) and without accompanying electrocardiograms (ECG) findings of LVH may be appropriate (class IIa; level of evidence C) [22]. Thus, the authors suggest that it is reasonable to avoid a donor heart presenting with posterior wall and interventricular septum thickness > 14 mm during diastole. The presence of aortic valve disease (stenosis or insufficiency) in the absence of left ventricular hypertrophy should not preclude donor considerations.

Careful attention must be paid to allograft ischemic time since bench valve surgery requires additional warm ischemic time. Currently, the allograft ischemic time is limited to 4–6 h. In fact, a study utilizing the UNOS database that included over 11,700 patients undergoing heart transplantation reported that ischemic time was an independent risk factor for survival in patients with an ischemic time > 6 hours [OR 1.7 (1.0–2.8), p < 0.05] and in patients with an ischemic time between 4 and 6 hours [OR 1.4 (1.3–1.6), p < 0.05] [23]. Several reports have shown that longer ischemic time is associated with a higher risk of mortality [24, 25]. Moreover, it has been reported that long cold ischemic time may introduce primary graft dysfunction, CAV, and increased length of stay in intensive care [26, 27]. Conversely, some

investigators have demonstrated that a prolonged ischemic time does not negatively impact the 1-year survival following heart transplantation [28, 29]. After the heart allocation policy was revised in the United States [3], it was reported that the mean total allograft ischemic time increased from 3.0 to 3.4 h (*P* < 0.001), with a concurrent increase in median distance between donor and recipient transplant centers from 83 to 216 miles [30]. Therefore, the acceptable maximum allograft ischemic time remains a matter of debate; however, a longer allograft ischemic time is not without risk.
