Comparison of hemodynamics and root configurations between remodeling and reimplantation methods for valve-sparing aortic root replacement: a pulsatile flow study.

PURPOSE: To compare the characteristics of reimplantation (RI) using grafts with sinuses and remodeling (RM) with/without external suture annuloplasty using a pulsatile flow simulator. METHODS: Porcine aortic roots were obtained from an abattoir, and six models of RM and RI with sinuses were prepared. External suture annuloplasty (ESA) was performed in the RM models to decrease the root diameter to 22 mm (RM-AP22) and 18 mm (RM-AP18). Valve models were tested at mean pulsatile flow and aortic pressure of 5.0 L/min and 120/80 (100) mmHg, respectively, at 70 beats/min. The forward flow, regurgitation, leakage, backflow rates, valve-closing time, and mean and peak pressure gradient (p-PG) were evaluated. Root configurations were examined using micro-computed tomography (micro-CT). RESULTS: The backflow rate was larger in the RM models than in the RI models (RI: 8.56% ± 0.38% vs. RM: 12.64% ± 0.79%; p < 0.01). The RM-AP and RI models were comparable in terms of the forward flow, regurgitation, backflow rates, p-PG, and valve-closing time. The analysis using a micro-CT showed a larger dilatation of the sinus of the Valsalva in the RM groups than in the RI group (Valsalva: RI, 26.55 ± 0.40 mm vs. RM-AP22, 31.22 ± 0.55 mm [p < 0.05]; RM-AP18, 31.05 ± 0.85 mm [p < 0.05]). CONCLUSIONS: RM with ESA and RI with neo-sinuses showed comparable hemodynamics. ESA to RM reduced regurgitation.

Aortic root geometry following valve-sparing root replacement with reimplantation or remodeling: experimental investigation under static continuous pressure.

The differences in aortic root geometry associated with various valve-sparing root replacement (VSRR) techniques have not fully been understood. We evaluated the root configuration of current VSRR techniques by developing in vitro test apparatus. Six fresh porcine hearts were used for each model. The aortic root remodeling control group involved replacement of the ascending aorta with diameter reduction of sino-tubular junction (STJ) (C1). The aortic valve reimplantation control group involved replacement of the ascending aorta alone (C2). VSRR included remodeling without (RM) or with annuloplasty (RM + A) and reimplantation with a tube (RI) or a handmade neo-Valsalva graft (RI + V). The root geometry of each model in response to closing hydraulic pressures of 80 and 120 mmHg was investigated using echocardiography. Among the VSRR models, RM yielded the largest aorto-ventricular junction (AVJ), which was similar to those in non-VSRR models [mean AVJ diameter (mm) at 80 mmHg; RM = 25.1 ± 1.5, RM + A = 20.9 ± 0.7, RI = 20.7 ± 0.9, RI + V = 20.8 ± 0.4]. RI + V yielded the largest Valsalva size and largest ratio of Valsalva/AVJ, which was similar to the control group [mean Valsalva diameter (mm) at 80 mmHg; RM = 28.4 ± 1.4, RM + A = 25.8 ± 1.3, RI = 23.6 ± 1.0, RI + V = 30.5 ± 0.8, ratio of Valsalva/AVJ at 80 mmHg; RM = 1.14 ± 0.06, RM + A = 1.24 ± 0.06, RI = 1.15 ± 0.06, RI + V = 1.47 ± 0.05]. The STJ diameter at 80 mmHg was numerically smaller with RM + A (22.4 ± 1.2 mm) than with RM (24.8 ± 2.3 mm, p = 0.11). There were no significant differences in AVJ, Valsalva, or STJ distensibility or ellipticity between procedures. Current modifications, including annuloplasty for remodeling or reimplantation in the setting of neo-Valsalva graft, yield near-physiological root geometries.