Acquired von Willebrand syndrome (AVWS) is a bleeding disorder caused by an acquired deficiency of von Willebrand factor (vWF). Some patients with AVWS show a low bleeding tendency and are diagnosed ...by the presence of a mild prolongation of activated partial thromboplastin time (APTT) preoperatively. Another cause of APTT prolongation is the presence of antiphospholipid antibody (aPL). We experienced a case of AVWS due to aortic valve stenosis in a patient with aPL in whom aortic valve replacement surgery was successful with vWF replacement. In patients with AVWS-associated disorders who are identified based on APTT prolongation at the preoperative examination, both vWF and aPL screening tests must be performed.
Background
A heart failure (HF) model using coronary microembolization in large animals is indispensable for medical research. However, the heterogeneity of myocardial response to microembolization ...is a limitation. We hypothesized that adjusting the number of injected microspheres according to coronary blood flow could stabilize the severity of HF. This study aimed to evaluate the effect of microsphere injection based on the left coronary artery blood flow in an animal model.
Methods
Microembolization was induced by injecting different numbers of microspheres (polystyrene, diameter: 90 μm) into the left descending coronary artery of the two groups of sheep (400 and 600 times coronary blood flow ml/min). Hemodynamic parameters, the pressure–volume loop of the left ventricle, and echocardiography findings were examined at 0.5, 1.5, 3.5, and 6.5 h after microembolization.
Results
End‐diastolic pressure and normalized heart rate increased over time, and were significantly higher in 600 × coronary blood flow group than those in 400 × coronary blood flow group (p = 0.04 and p < 0.01, respectively). The maximum rate of left‐ventricular pressure rise and normalized stroke volume decreased over time, and were significantly lower in 600 × coronary blood flow group than those in 400 × coronary blood flow group (p < 0.01 and p < 0.01, respectively). The number of microspheres per coronary blood flow was significantly correlated with the decrease in stroke volume and the maximum rate of left ventricular pressure rise in 6.5 h (r = 0.74, p = 0.01 and r = 0.71, p = 0.02, respectively).
Conclusions
Adjusting the number of injected microspheres based on the coronary blood flow enabled the creation of HF models with different degrees of severity.
In large animal models of coronary microembolization, the heterogeneity of myocardial response to microembolization is a limitation. We demonstrated that adjusting the number of injected microspheres based on the left coronary blood flow enabled the creation of heart failure models with different degrees of severity. CBF, coronary blood flow; LV dP/dt max, maximum rate of left ventricular pressure rise; LVEDP, left ventricular end‐diastolic pressure; ME, microembolization; SV, stroke volume.
We developed a new artificial placenta (AP) system consisting of a loop circuit configuration extracorporeal membrane oxygenation (ECMO) with a bridge circuit designed to be applied to the fetus in ...the form of an umbilical arterial–venous connection. We aimed to evaluate the feasibility of the AP system by performing a hydrodynamic simulation using a mechanical mock circulation system and fetal animal experiment. The effect of the working condition of the AP system on the fetal hemodynamics was evaluated by hydrodynamic simulation using a mechanical mock circulation system, assuming the weight of the fetus to be 2 kg. The AP system was introduced to two fetal goats at a gestational age of 135 days. The general conditions of the experimental animals were evaluated. The mock simulation showed that in an AP system with ECMO in the form of an umbilical arterial–venous connection in series, it could be difficult to maintain fetal hemodynamics when high ECMO flow was applied. The developed AP system could have high ECMO flow with less umbilical blood flow; however, the possibility of excessive load on the fetal right-sided heart should be noted. In the animal experiment, kid 1 (1.9 kg) was maintained on the AP system for 12 days and allowed to grow to term. In kid 2 (1.6 kg), the AP system could not be established because of the occlusion of the system by a thrombus. The developed AP system was feasible under both in vitro and in vivo conditions. Improvements in the AP system and management of the general fetal conditions are essential.
Under continuous-flow left ventricular assist device (CF-LVAD) support, the ventricular volume change and cardiac cycle between the left ventricle (LV) and right ventricle (RV) become dyssynchronous ...due to the shortening of the LV systole. The purpose of this study was to quantify interventricular dyssynchrony based on different CF-LVAD support conditions and assess its relationship with LV unloading. In this study, we evaluated seven goats (body weight 44.5 ± 6.5 kg) with normal hearts. A centrifugal LVAD was implanted under general anesthesia. We inserted the conductance catheters into the left ventricle (LV) and right ventricle (RV) to assess the volume signal simultaneously. We defined the interventricular dyssynchrony as a signal (increase or decrease) of LV volume (LVV) change opposite to that of RV volume (RVV) (i.e., (
d
LVV/
d
t) × (
d
RVV/
d
t) < 0). The duration of interventricular dyssynchrony (DYS) was reported as the percentage of time that a heart was in a dyssynchronous state within a cardiac cycle. The mean DYS of normal hearts, hearts with LVAD clamp and hearts supported by LVADs with a bypass rate of 50%, 75% and 100% were 5.6 ± 1.6%, 8.7 ± 2.4%, 8.6 ± 2.8%, 15.1 ± 5.1%, and 25.6 ± 8.0%, respectively. Furthermore, the DYS was found to be associated with the degree of LV stroke volume reduction caused by LV unloading. These findings may be useful for understanding interventricular interactions and physiology during CF-LVAD support. Influences on the right ventricular function and heart failure models warrant further study.
Abstract Background In valve-sparing aortic root replacement (VSARR), how to reproduce Valsalva sinus has been an issue. In the original David V procedure, they put plication stitches at sinotubular ...junction level, although the reefing effect is limited and distal graft remains larger than native. Other modified techniques are two-grafts technique and ready-made Valsalva graft. However, the former needs graft–graft anastomosis and may not be cost-effective, while in the latter, the shape of sinus is fixed and minor adjustment is difficult. David V University of Tokyo modification (David V-UT) is our original solution to that, creating pseudosinus with one straight graft by longitudinal size-reduction running sutures above each pseudosinus. The purpose of the present study is to investigate long-term outcome of David V-UT. Methods We analyzed 59 David V-UT patients from February 2004 to February 2013 and long-term outcomes were investigated by Kaplan–Meier methods. Risk factors for adverse events “death or recurrent aortic insufficiency (AI) with or without aortic valve reoperation” were analyzed by using Cox proportional hazard models. Results Mean age was 33.1 ± 14.5 years, and 38 patients (64%) were male. Marfan syndrome (MFS) accounts for 47 patients (80%). Only one patient was with bicuspid aortic valve. No in-hospital mortality was observed. Mean follow-up was 4.9 ± 2.4 years. Estimated survival was 94.0 ± 3.4% at 5 years. Freedoms from aortic valve reoperation and recurrent AI greater than mild were 95.7 ± 3.0% and 88.9 ± 4.7% at 5 years, respectively. In Cox proportional hazard analysis, preoperative AI greater than mild and Z score of annular diameter were significant risks for adverse events ( p = 0.027 and 0.045, hazard ratio 6.084 and 1.432, 95% C.I. 1.225–30.21 and 1.008–2.035, respectively). Conclusions Even in Marfan-characterized population, David V-UT provided satisfactory long-term outcome, comparable to other VSARR modifications. It is simple but can freely reproduce trilobed sinus with one straight graft.
The purpose of this study was to observe and clarify the interventricular dysscynchrony caused by continuous-flow left ventricular assist device (CF-LVAD) support using the conductance method. During ...CF-LVAD support, the systolic phase of the left ventricle (LV) becomes shorter than that of the right ventricle (RV). Accordingly, timing of the systole and diastole during the cardiac cycle is not synchronous between the LV and RV. In this study, we evaluated this phenomenon in a normal heart model using the adult goat (
n
= 5, body weight 44.5 ± 2.9 kg). A centrifugal LVAD was implanted under general anesthesia. We inserted the conductance catheter into the RV and LV to obtain the pressure–volume relationship of the two ventricles simultaneously. We defined the dyssynchronous status as the sign (plus or minus) of the LV volume-change opposite to that of RV volume-change. Dyssynchronous phase of the cardiac cycle was observed in 5.6 ± 0.65% of hearts under LVAD pump-off and 25.3 ± 3.3% under LVAD full bypass, respectively (
p
< 0.05). To the best of our knowledge, this is the first experimental report clarifying interventricular dyssynchrony during CF-LVAD support using the conductance method. Quantification of this phenomenon under various support conditions and assessment of influences on the right ventricular function will be studied in future studies.
Continuous-flow left ventricular assist devices (LVADs) have improved the prognosis of end-stage heart failure. However, continuous-flow LVADs diminish pulsatility, which possibly result in bleeding, ...aortic insufficiency, and other adverse effects. We previously developed a novel control system for a continuous-flow LVAD (EVAHEART
®
; Sun Medical), and demonstrated that we could create sufficient pulsatility by increasing its rotational speed (RS) in the systolic phase (Pulsatile Mode) in the normal heart model. Here, we aimed to evaluate differences between systolic assist with advanced and delayed loads by shifting the timing of increased RS. We implanted EVAHEART in six goats (55.3 ± 4.3 kg) with normal hearts. We reduced their heart rates to <60 bpm using propranolol and controlled the heart rates at 80 and 120 bpm using ventricular pacing. We shifted the timing of increasing RS from −60 to +60 ms in the systolic phase. We found significant increases in all the following parameters when assessments of delayed timing (+60 ms) were compared with assessments of advanced timing (−60 ms): pulse pressure, mean d
P
/d
t
max of aortic pressure, and energy-equivalent pulse pressure. During continuous-flow LVAD support, pulsatility can be controlled using a rotary pump. In particular, pulsatility can be shifted by delaying increased RS.
Objective We previously developed a native heart load control system for a continuous-flow left ventricular assist device and demonstrated that the rotational speed synchronized with the cardiac ...cycle can alter left ventricular preload and myocardial oxygen consumption. In the present study, we assessed this system in a conscious goat model of chronic heart failure. Methods Chronic heart failure was induced by coronary microsphere embolization of the left ascending artery and subsequent rapid ventricular pacing in 6 goats. After 4 to 6 weeks of rapid pacing, the goats showed a decreased ejection fraction (from 89.7% ± 3.1% to 53.3% ± 5.4%) measured during sinus rhythm. The assist device was implanted by way of a left thoracotomy, and we examined the effects of the continuous, co-pulse, and counterpulse mode on the end-diastolic volume and stroke work, determined from the left ventricular pressure–volume loops. Results Significant decreases were found in the end-diastolic volume and stroke work in the counterpulse mode relative to the values observed with 0% bypass (63.4% ± 15.2% and 39.1% ± 18.2%, respectively; P < .01). Furthermore, both increased in the co-pulse mode (82.1% ± 17.6% and 68.3% ± 22.2%; P < .01) compared with those in the continuous mode (69.6% ± 15.4% and 54.6% ± 21.6%) with 100% bypass. Conclusions The system offers the possibility to control the left ventricular load by changing the rotational speed of a continuous-flow assist device in synchronization with the cardiac cycle. This system should provide the most favorable left ventricular loading conditions for recovery of the native heart.
We have previously developed a native heart load control system for a continuous-flow left ventricular assist device (LVAD) ((EVAHEART
®
; Sun Medical) and demonstrated that the rotational speed (RS) ...in synchronization with the cardiac cycle can alter pulsatility and left ventricular (LV) load under general anesthesia. In this study, we assessed the effects of different levels of increase in RS on pulsatility and LV load in the chronic awake phase. We implanted the EVAHEART via left thoracotomy in 7 normal goats (59.3 ± 4.6 kg). Two weeks after implantation, we examined the effects of co-pulse mode (increased RS in the systolic phase) and counter-pulse mode (increased RS in the diastolic phase), as well as shifting the change in RS from 250 to 500 rpm, and 750 rpm in both modes on pulsatility and LV load. Pulsatility was assessed using pulse pressure and mean dP/dt max of aortic pressure. LV load was assessed using stroke work and left ventricle end-diastolic volume determined from LV pressure–volume loops. In the co-pulse mode, pulsatility values increased as the change in RS increased. By contrast, in the counter-pulse mode, these values decreased as the change in RS increased. LV load increased significantly in the co-pulse mode compared with the counter-pulse mode, but there were no significant differences among the three levels of RS increase in either mode. Increasing RS to varying degrees with our newly developed system could contribute to pulsatility. However, it appeared to have little effect on LV load in normal hearts.
Excessive left ventricular (LV) volume unloading can affect right ventricular (RV) function by causing a leftward shift of the interventricular septum in patients with mitral regurgitation (MR) ...receiving left ventricular assist device (LVAD) support. Optimal settings for the LVAD should be chosen to appropriately control the MR without causing RV dysfunction. In this study, we assessed the utility of our electrocardiogram‐synchronized rotational speed (RS) modulation system along with a continuous‐flow LVAD in a goat model of MR. We implanted EVAHEART devices after left thoracotomy in six adult goats weighing 66.4 ± 10.7 kg. Severe MR was induced through inflation of a temporary inferior vena cava filter placed within the mitral valve. We evaluated total flow (TF; the sum of aortic flow and pump flow PF), RV fractional area change (RVFAC) calculated by echocardiography, left atrial pressure (LAP), LV end‐diastolic pressure (LVEDP), LV end‐diastolic volume (LVEDV), and LV stroke work (LVSW) with a bypass rate (PF divided by TF) of 100% under four conditions: circuit‐clamp, continuous mode, co‐pulse mode (increased RS during systole), and counter‐pulse mode (increased RS during diastole). TF tended to be higher in the counter‐pulse mode. Moreover, RVFAC was significantly higher in the counter‐pulse mode than in the co‐pulse mode, whereas LAP was significantly lower in all driving modes than in the circuit‐clamp condition. Furthermore, LVEDP, LVEDV, and LVSW were significantly lower in the counter‐pulse mode than in the circuit‐clamp condition. The counter‐pulse mode of our RS modulation system used with a continuous‐flow LVAD may offer favorable control of MR while minimizing RV dysfunction.
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