Effects of Long-Term Nonpulsatile Left Heart Bypass on the Mechanical Properties of the Aortic Wall

Nishimura, Takashi; Tatsumi, Eisuke; Taenaka, Yoshiyuki; Nishinaka, Tomohiro; Nakatani, Takeshi; Masuzawa, Toru; Nakata, M; Nakamura, Makoto; Endo, Seiko; Takano, Hisateru

doi:10.1097/00002480-199909000-00017

Cited by 31 publications

(15 citation statements)

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“…In this study the pulse pressure was reduced to about 10mmHg, which we considered a clinically available level. Furthermore, although the purpose of this study was to investigate changes in vascular control status that were possibly affected by atrophic changes in the arterial systems accompanying reduced pulse pressure, Nishimura et al [4][5][6] reported that atrophic changes in the arterial system were observed with a pulse pressure of about 10mmHg.…”

Section: Discussionmentioning

confidence: 98%

“…The influences of reduced systemic pulse pressure have been investigated in nonpulsatile left heart bypass (NLHB). Nishimura et al [4][5][6] reported morphological changes in the arterial system caused by prolonged NLHB in a chronic animal study. There was an increase in the ratio of elastin, a decrease in arterial wall thickness, and atrophy of smooth muscle cells.…”

Section: Introductionmentioning

confidence: 99%

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Effect of prolonged nonpulsatile left heart bypass on vascular control status

et al. 2000

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We investigated the vascular control status, including vasoactive hormones, systemic vascular resistance (SVR), and baroreceptor sensitivity, in prolonged nonpulsatile left heart bypass (NLHB). Nine goats underwent pulsatile left heart bypass (PLHB) with a ventricular assist device (VAD). Two weeks postoperatively, the VAD was replaced with a centrifugal pump and NLHB was subsequently conducted for 4 weeks. Thirteen healthy goats were also evaluated to obtain normal control data. The aortic pulse pressure on average was 37 mmHg for controls; 36mmHg at the end of PLHB; and 11, 9, 12, and 12mmHg at the end of the first, second, third, and fourth NLHB weeks, respectively. Plasma norepinephrine (NE), vasopressin (VP), renin activity (RA), and endothelin-i (ET) levels were measured for controls and at each point during PLHB and NLHB. The baseline SVR and the minimum SVR values after nitroglycerin injection were determined at each point during PLHB and NLHB. Baroreceptor sensitivity was calculated as the regression slope between R-R intervals and mean aortic pressure for controls and at each point during PLHB and NLHB. The plasma levels of NE, VP, RA, and EN did not change significantly during the entire course of the experiments. The baseline and minimum SVR values after nitroglycerin injection remained unchanged during PLHB and NLHB. Furthermore, the baroreceptor sensitivity did not change significantly during the entire course of the experiments. These results indicate that prolonged NLHB does not affect vascular control

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Section: Discussionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

Effect of prolonged nonpulsatile left heart bypass on vascular control status

et al. 2000

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“…5). 27 This finding suggests that the opposite influences of changes in wall thickness and constituent volume ratios canceled each other out and, consequently, stabilized this mechanical property.…”

Section: Changes In Mechanical Propertiesmentioning

confidence: 92%

Aortic reaction to prolonged nonpulsatile left heart bypass

et al. 1999

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We investigated the reaction of the vascular system to prolonged nonpulsatile left heart bypass (LHB) using adult goats that underwent chronic nonpulsatile LHB. On morphological examination of the aorta, we found a decrease in wall thickness, a decrease in constituent volume ratio of smooth muscle, and an increase in the ratio of elastin. The atrophic change was further confirmed by an increase in smooth muscle cell density and an increase in smooth muscle cells, which exhibited atrophy-specific changes on electron microscopic observation. The changes in mechanical properties accompanying these morphological changes were evaluated according to stiffness parameter and pulse wave velocity. No significant changes in those parameters were caused by prolonged nonpulsatile LHB. The change in vascular contractility was evaluated by the response of systemic vascular resistance to norepinephrine and nitroglycerin administration. Vascular contractility was markedly decreased by prolonged nonpulsatile LHB. These results indicated that the significant morphological changes, including aortic structure and smooth muscle atrophy, were caused by prolonged nonpulsatile LHB. However, these changes did not accompany the changes in mechanical properties. In contrast, this distinctive LHB modality caused a decrease in vascular contractility. Key wordsNonpulsatile left heart bypass 9 Aorta -Morphology 9 Mechanical property 9 Systemic vascular resistance

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“…Westaby, et al and Nishimura, et al have demonstrated that remodeling of the aortic root emerges along with thinning of the aortic wall under reduced pulsatility, which is attributable to apoptosis of smooth muscle cells and fragmentation of elastic fibers. 58,59) Remodeling and dilatation of the aortic root is associated with a higher prevalence of AI as well as the degeneration of the aortic valve and enlargement of the aortic ring. 20) Other than reduced pulsatility, we have to take into consideration geometric alteration of AV by commissural fusion and flow turbulence in the ascending aorta.…”

Section: Opening Of Native Av and Aimentioning

confidence: 99%

Preoperative Prediction of Aortic Insufficiency During Ventricular Assist Device Treatment

Imamura

Kinugawa

2016

Int. Heart J.

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SummarySurvival rate in patients with stage D heart failure has improved significantly owing to the development of continuous flow left ventricular assist devices (LVAD), but aortic insufficiency (AI) still remains one of the major unsolved complications that impairs patient quality of life. There are no established treatments for AI, and preoperative prediction and prevention of AI is needed. The opening of a native aortic valve (AV) is a sufficient condition for prevention of AI, and improvement of LV ejection fraction due to LV reverse remodeling (LVRR) is essential to open a native AV. Preoperative insufficient β-blocker treatment and pulsatile flow LVAD usage are keys for LVRR, opening of an AV, and prevention of AI. The second mechanism that leads to AI is remodeling of the aortic root and degeneration of a native AV, which results from reduced pulse pressure during LVAD support. Centrifugal or pulsatile flow LVAD usage has an advantage in terms of preserving pulsatility, and may prevent AI compared with an axial pump. There is less probability of avoiding AI with sufficient β-blocker treatment, and these patients may be good candidates for concomitant surgical intervention to a native AV at the time of LVAD implantation. (Int Heart J 2016; 57: 3-10)Key words: Pulsatility, VAD, Carvedilol, Aortic valve C urrently, the survival rate in patients with advanced heart failure (HF) has improved due to the development of continuous flow (CF) left ventricular assist device (LVAD) treatment and improvement of perioperative management procedures.1-9) However, quality of life during CF LVAD is still not satisfactory because of several unresolved postoperative complications. 4,10,11) One of the major complications is aortic insufficiency (AI), which is characterized as continuous aortic regurgitation during both systolic and diastolic phases through a degenerated and occasionally fusional native aortic valve (AV) ( Figure 1AB). 12,13) Native AV, which is apparently normal before LVAD implantation, can be associated with a considerable level of AI after LVAD implantation. Post-LVAD AI can develop even in the preoperative setting in which there is no aortic regurgitation at all. 12,14,15) In 2000, Rose, et al first documented acquired AV disease during pulsatile flow (PF) LVAD. They identified evidence of commissural fusion of native AV.16) In 2006, Frazier, et al summarized the relationship between commissural fusion of native AV and development of AI during CF LVAD treatment.17) We also showed that AI was more frequently observed in patients with CF LVAD as compared with PF pump in 2011 ( Figure 1C). 18) Since then, a number of single-center studies have documented a wide-ranging prevalence of AI during LVAD treatment. 15,[19][20][21] The development of AI during LVAD treatment is considered to be a multifactorial phenomenon and a result of altered AV and aortic root biomechanics due to chronic and continuous ventricular unloading. Unloading of LV results in ventricular decompression, and the combination of systolic ...

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Effects of Long-Term Nonpulsatile Left Heart Bypass on the Mechanical Properties of the Aortic Wall

Cited by 31 publications

References 0 publications

Effect of prolonged nonpulsatile left heart bypass on vascular control status

Effect of prolonged nonpulsatile left heart bypass on vascular control status

Aortic reaction to prolonged nonpulsatile left heart bypass

Preoperative Prediction of Aortic Insufficiency During Ventricular Assist Device Treatment

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