ABSTRACT
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.
Subject(s)
Humans , Cardiovascular System , Diastole , Heart Failure , Heart Rate , Heart-Assist Devices , Hemodynamics , Models, CardiovascularABSTRACT
Purpose : Easy and safe implantability, good post-operative valve function and good long-term durability are required for any bioprosthetic valve implanted in aortic position. The Carpentier Edwards Perimount Magna valve (Magna) was introduced in 2009 and the St. Jude Medical Trifecta valve (Trifecta) was introduced in 2012 to our institution. In this study, we compared implantability, early post-operative valve function and structural valve deterioration (SVD) between these two valves. Patients and Methods : Between January 2009 and December 2019, Magna or Trifecta were electively implanted for 254 patients (Magna 151 patients and Trifecta 103 patients) and these patients were included in this study. Implantability was evaluated by occurrence of intraoperative valve dysfunction. Early post-operative valve function was evaluated by mean pressure gradient (m-PG) and indexed aortic valve area (AVAI) by ultrasonography performed 10 days after surgery. The relationship between indexed bioprosthetic valve orifice area calculated from internal diameter (GOAI) and AVAI was evaluated. If there was a significant relationship between GOAI and AVAI, maximum body surface area (BSA) to obtain AVAI≥0.85 cm2/m2 was estimated from 99% reliable interval of regression line. Results : Age, gender, and BSA did not differ between the two groups. There was no intraoperative valve dysfunction in Magna ; however we experienced one patient with severe aortic regurgitation due to stent distortion by the aortic wall during surgery with the 25 mm Trifecta valve. For this patient, Trifecta was replaced with Magna intra-operatively. In the 19 mm valve, AVAI was significantly larger (1.12±0.27 cm2/m2 vs. 0.88±0.21 cm2/m2, p<0.001) and m-PG was significantly lower (8.7±2.7 mmHg vs. 17.2±6.3 mmHg, p<0.001) in Trifecta. The frequency of AVAI<0.85 cm2/m2 (24% vs. 49%, p=0.036) and the frequency of m-PG≥20 mmHg (0% vs. 26%, p=0.006) were significantly less in Trifecta. There was significant relationship between GOAI and AVAI in both valves. Maximum BSA to obtain AVAI ≥0.85 cm2/m2 was estimated as 1.35 m2 in Magna and 1.50 m2 in Trifecta. In the 21 mm valve, AVAI was significantly larger (1.14±0.23 cm2/m2 vs. 0.92±0.22 cm2/m2, p<0.001) and m-PG was significantly lower (7.8±3.2 mmHg vs. 14.6±4.7 mmHg, p<0.001) in Trifecta. The frequency of AVAI<0.85 cm2/m2 was significantly less in Trifecta (11% vs. 42%, p=0.002) ; however, the frequency of m-PG≥20 mmHg did not differ significantly. There was a significant relationship between GOAI and AVAI in Magna and Trifecta. Maximum BSA to obtain AVAI ≥0.85 cm2/m2 was estimated as 1.49 m2 in Magna and 1.70 m2 in Trifecta. In the 23 and 25 mm valves, AVAI was significantly larger and m-PG was significantly lower in Trifecta. However neither the frequency of AVAI<0.85 cm2/m2 nor m-PG≥20 mmHg differed between the two valves. There was one early (27 months after surgery) SVD due to leaflet tear in Trifecta and two SVDs due to leaflet calcification more than 10 years after surgery in Magna. Conclusion : For Trifecta implantation, valve size selection seemed to be important and larger valves should be avoided with narrow ST junctions. Selection of 19 and 21 mm Magna valves should be limited for the patient with a BSA less than 1.35 and 1.49 m2 respectively. In Trifecta, early SVD might occur and careful follow-up is necessary.
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@#Objective To compare vein valve function following pharmacomechanical thrombolysis (PMT) with simple catheter-directed thrombolysis (CDT) for deep vein thrombosis. Methods We retrospectively analyzed the clinical data of sixty patients who suffered acute lower extremity deep vein thrombsis in our hospital between October 2016 and March 2017. All patients underwent contralateral preprocedural duplex and bilateral postprocedure duplex to access patency and valve function. The patients were divided into three groups including a group A with catheter-directed thrombolysis (CDT) alone (36 patients with 20 males and 16 females at average age of 56 years), a group B with PMT alone (15 patients with 8 males and 7 females at average age of 55 years), and a group C with PMT combined CDT (9 patients with 4 males and 5 females at average age of 56 years). The valve function was compared among the Group A, Group B and Group C. Results There were 40.0% (24/60) patients with bilateral femoral vein valve reflux, 40.0% (24/60) patients with unilateral femoral vein valve reflux (all in the treated limbs), 20% (12/60) patients had no reflux in both limbs. Of the limbs treated with CDT alone, PMT alone and PMT combined CDT, the rate of valve reflux was 38.9% (14/36), 33.3% (5/15), and 55.6% (5/9) respectively (P=0.077). Conclusion In the patients suffering acute DVT, PMT or PMT combined CDT does not hamper valve function compared with CDT alone.
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Objective To evaluate improved effect for deep venous valve function after superficial vein surgery of lower extremity in the intermediate stage.Methods Totally 43 patients (55 limbs) with varicose veins of lower extremity were enrolled to accept surgical management of vein systems in our department from March 2006 to October 2006.All patients were respectively followed up after 6 months and 4 years about the changes of deep venous valve function with color Doppler ultrasonography.Results Thirty-nine patients’ deep venous valve function kept well up to now,and there was no significant difference between the two results.Four patients without proximal saphenous vein ligation recurred,and there was reflux in deep venous.Conclusion Endovenous laser treatment and ablation of varicose veins of lower extremity with deep venous insufficiency could improve deep venous valve function effectively.Proximal great saphenous vein ligation is important for successful operation.