[Effect of a delay mode of a ventricular assist device on hemodynamics of the cardiovascular system].

The implantation of biventricular assist device (BiVAD) is more challenging than that of left ventricular assist device for the interaction in the process of multiple input and output. Besides, ventricular assist device (VAD) often runs in constant speed (CS) mode in clinical use and thus BiVAD also faces the problems of low pulsation and imbalance of blood volume between systemic circulation and pulmonary circulation. In this paper, a delay assist mode for a VAD by shortening the support time of VAD was put forward. Then, the effect of the delay mode on cardiac output, pulsation and the function of the aortic valve was observed by numerical method and the rules of hemodynamics were revealed. The research showed that compared with VAD supported in CS mode, the VAD using delay mode in systolic and diastolic period proposed in this paper could meet the demand of cardiac output perfusion and restore the function of the arterial valves. The open ratio of aortic valve (AV) and pulmonary valve (PV) increased with the time set in delay mode, and the blood through the AV/PV helped to balance the left and the right cardiac volume. Besides, delay mode also improved the pulsation index of arterial blood flow, which is conducive to the recovery of the ventricular pulse function of patients.

Effect of a delay mode of a ventricular assist device on hemodynamics of the cardiovascular system / 生物医学工程学杂志

The implantation of biventricular assist device (BiVAD) is more challenging than that of left ventricular assist device for the interaction in the process of multiple input and output. Besides, ventricular assist device (VAD) often runs in constant speed (CS) mode in clinical use and thus BiVAD also faces the problems of low pulsation and imbalance of blood volume between systemic circulation and pulmonary circulation. In this paper, a delay assist mode for a VAD by shortening the support time of VAD was put forward. Then, the effect of the delay mode on cardiac output, pulsation and the function of the aortic valve was observed by numerical method and the rules of hemodynamics were revealed. The research showed that compared with VAD supported in CS mode, the VAD using delay mode in systolic and diastolic period proposed in this paper could meet the demand of cardiac output perfusion and restore the function of the arterial valves. The open ratio of aortic valve (AV) and pulmonary valve (PV) increased with the time set in delay mode, and the blood through the AV/PV helped to balance the left and the right cardiac volume. Besides, delay mode also improved the pulsation index of arterial blood flow, which is conducive to the recovery of the ventricular pulse function of patients.

Sex-differences in echocardiographic assessment of aortic valve in young adult LDLr-/-/ApoB100/100/IGF-II+/- mice.

BACKGROUND: LDLr-/-/ApoB100/100/IGF-II+/- mice are used as a calcific aortic valve disease (CAVD) model. However, normal aortic valve hemodynamics i.e. remotely from CAVD onset and the sex-related differences are poorly known. METHODS AND RESULTS: Four groups of mice, intact males (IM, n = 49) and females (IF, n = 50), castrated males (CxM, n = 79) and ovariectomized females (OxF: 73), underwent a Doppler-echocardiography at 12 weeks of age. Gonadectomy was performed at 8 weeks. Aortic valve assessment using effective orifice area (EOA, using the continuity equation) and peak aortic transvalvular velocity (VPeak) was feasible in 89% of the mice with good to excellent reliability (intraclass correlation coefficients ranging from 0.90 to 0.98, p < 0.001). Mean VPeak was 104 ± 17 cm/s and mean EOA was 1.18*10-2 ± 0.22*10-2 cm2. EOA indexed to body surface area was 1.5 ± 0.3 cm2/m2. The 95th percentile of Vpeak was 132 cm/s and the 5th percentile of indexed EOA was 1.0 cm2/m2. Interestingly, IM had the highest VPeak (114 ± 14 cm/s) vs each of the other groups (CxM: 106 ± 19 cm/s, OxF: 97 ± 13 cm/s and IF: 96 ± 12 cm/s, ANOVA and corrected p < 0.001). This was mostly explained by a higher stroke volume (ANOVA and corrected p < 0.001) in IM compared to other groups. There were no major sex-differences in ventricular systolic function parameters. CONCLUSION: In LDLr-/-/ApoB100/100/IGF-II CAVD mice model, an aortic EOA <0.8*10-2 cm2 (or indexed EOA <1.0cm2/m2), and a peak aortic valve velocity > 132 cm/s may be proposed as thresholds to define CAVD. Intact male mice appear to have higher velocities.

Mid-term Clinical Outcomes in a Cohort of Asymptomatic or Mildly Symptomatic Korean Patients with Bicuspid Aortic Valve in a Tertiary Referral Hospital.

BACKGROUND: Although bicuspid aortic valve (BAV) is one of the most common congenital heart diseases, clinical outcome data regarding BAV are still limited. We evaluated clinical characteristics and mid-term clinical outcomes of asymptomatic Korean patients with bicuspid aortic valve. METHODS: We initiated a prospective registry in 2014 at a tertiary referral hospital. To develop a cohort of asymptomatic patients, we excluded patients who previously underwent open heart surgery (OHS) or who had OHS within 6 months of referral. RESULTS: A total of 170 patients (117 male [69%], age 50 ± 13 years) were enrolled. More than 70% (n = 124, 73%) were incidentally diagnosed with BAV during routine health examinations or preoperative screening for non-cardiac surgery. At the time of enrollment, moderate to severe aortic stenosis (AS) or regurgitation (AR) was present in 77 patients (45%) and 98 (58%) showed aortic dilation: 42 (25%) had non-significant valvular dysfunction without aortic dilation. During a median follow-up of 4 years, AS severity increased significantly (p < 0.001), while there was no significant change in AR severity (p = 0.361). A total of 27 patients (16%) underwent OHS, including isolated aortic valve (AV) surgery (n = 11, 41%), AV with combined aortic surgery (n = 12, 44%), and isolated aortic surgery (n = 4, 15%): no patient developed aortic dissection. Moderate to severe AS (hazard ratio [HR] 4.61; 95% confidence interval [CI] 1.83-11.62; p = 0.001), NYHA class ≥ 2 (HR 2.53; 95% CI 1.01-6.35; p = 0.048) and aortic dilation (HR 2.13; 95% CI 0.87-5.21; p = 0.099) were associated with surgical events. CONCLUSIONS: Progression patterns of valvular dysfunction and impacts of BAV phenotype on OHS should be explored in future studies with longer follow-up durations.

Outcome in Children Operated for Membranous Subaortic Stenosis: Membrane Resection Plus Aggressive Septal Myectomy Versus Membrane Resection Alone.

BACKGROUND: The optimal surgical procedure for treatment of fibromembranous subaortic stenosis has been a subject of debate. We report our experience with patients treated for membranous subaortic stenosis using membrane resection alone and membrane resection plus aggressive septal myectomy. METHODS: Patients followed in the pediatric cardiology clinic of a university hospital, who had undergone surgery for subaortic stenosis between 2002 and 2013 were reviewed. Recurrence of subaortic membrane, residual left ventricular outflow gradient, and aortic valve function were analyzed. RESULTS: Forty-six patients underwent surgery for subaortic membrane. Of these, 19 had membrane resection plus aggressive septal myectomy, while 27 had membrane resection alone. Mean age at surgery for the membrane resection group was 7.7 ± 3.9 years and 10.9 ± 3.6 years for the membrane resection plus aggressive myectomy group. Preoperative subaortic gradient for the membrane resection group was 75.5 ± 26.7 mm Hg and 103.2 ± 39.7 mm Hg for the membrane resection plus aggressive myectomy group. The mean follow-up left ventricular outflow tract gradient was 42.3 ± 31.3 mm Hg in the membrane resection group, while it was 11.6 ± 6.3 mm Hg in the aggressive septal myectomy group. Nine patients from the membrane resection group had significant regrowth of the subaortic membrane during the follow-up period, while none of the aggressive septal myectomy group had detectable membrane on echocardiography. Seven of the nine patients with recurrence of the subaortic membrane underwent subsequent membrane resection plus aggressive septal myectomy. Intraoperative finding in all these redo cases was recurrence (growth) of a subaortic membrane. CONCLUSION: Aggressive septal myectomy offers less chance of recurrence, freedom from reoperation, and an improved aortic valve function. This is especially important in sub-Saharan settings where a chance of getting a second surgery is unpredictable.