Efficiency of energy transfer from pressure-volume area to external mechanical work increases with contractile state and decreases with afterload in the left ventricle of the anesthetized closed-chest dog.

Nozawa, Takashi; Yasumura, Yoshio; Futaki, Shiho; Tanaka, Norio; Uenishi, Masaaki; Suga, Hiroyuki

doi:10.1161/01.cir.77.5.1116

Cited by 115 publications

(64 citation statements)

References 23 publications

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“…Evaluation of left ventricular systolic performance in the PV plane during load alterations has given investigators a more specific tool to assess contractility in the in situ heart, because there appears to be less load dependency of such PV relationships than there is using single-beat preejection or ejection phase indices of performance (14,18,19). The conductance catheter has been used in the adult dog and human simultaneously with micromanometer pressure measurements for the repeated and instantaneous display and acquisition of PV loops without affecting ventricular function (13,26,29,36,43). PV loops have been analyzed by a variety of techniques (13,14,35,(44)(45)(46), but most commonly by generating ESPVR, to assess ventricular function in control conditions and in response to various hemodynamic perturbations.…”

Section: Parallel Conductance Versus Esv and Edvmentioning

confidence: 99%

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The End-Systolic Pressure-Volume Relationship in the Newborn Lamb: Effects of Loading and Inotropic Interventions

et al. 1991

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ABSTRACT. Indices of global systolic performance of the newborn left ventricle exceed those of the adult, despite isolated tissue studies showing immature contractile mechanisms. To evaluate contractility in situ, we investigated the end-systolic pressure-volume relationship (ESPVR) by the conductance technique in nine newborn lambs. After percutaneous placement of catheters, we generated ESPVR by inferior vena cava occlusion, aortic occlusion, and volume infusion in two control states, during three levels of dobutamine infusion, and after propranolol. We performed linear and nonlinear regression analyses of the end-systolic points and derived the slope (E.,) and volume at 14 kPa pressure. We found that reliable ESPVR could be obtained in almost all inferior vena cava and aortic occlusions (50 of 51 in each), but in only 18 of 27 volume infusions. Overall, linear regressions adequately defined the ESPVR (75 of 102 were not statistically different than nonlinear regressions; of those different, the mean linear R 2 was 0.934 ± 0.048). By multiple regression analysis, neither E es nor volume at 14 kPa significantly changed with dobutamine, but both changed after propranolol (23% less than control and 54% greater, respectively), supporting previous studies showing a limited contractile reserve in the newborn secondary to high resting p-adrenergic tone. Neither E., nor volume at 14 kPa was different between control states. However, E e , was 25% less steep when generated by inferior vena cava than by aortic occlusion. We conclude that the ESPVR can be generated reliably and reproducibly in the newborn lamb and is relatively linear and sensitive to changes in contractility, but that it is also sensitive to the technique of load intervention.

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Section: Parallel Conductance Versus Esv and Edvmentioning

confidence: 99%

“…In the adult, it has been extensively validated in situ in the dog and human (31)(32)(33) and in the isolated dog heart (34), and has been used to construct the ESPVR in both species (13,14,26,29,35,36). In the newborn, we have recently validated the catheter in the piglet against biplane cineangiography (37).…”

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confidence: 99%

The End-Systolic Pressure-Volume Relationship in the Newborn Lamb: Effects of Loading and Inotropic Interventions

et al. 1991

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“…So far, mechanical energy transfer using the PVA concept has been examined only under unphysiological states such as excised hearts or anesthetized animal models. [6][7][8][9] In the present study, we have extended the analysis of efficiency of energy transfer6'8 for the first time to human left ventricles. To clarify the insensitivity of mechanical efficiency to cardiac deterioration, we have examined, in patients with normal and moderately depressed hearts, how the changes in contractile state and afterload influence the MVo2-PVA relation and mechanical efficiency.…”

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confidence: 96%

Energy conversion efficiency in human left ventricle.

et al. 1992

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Background. Left ventricular mechanical efficiency is one of the most important measures of left ventricular pump performance. Several clinical studies, however, have shown that mechanical efficiency does not fall substantially as the heart fails. To clarify the insensitivity of mechanical efficiency to the change in pump performance, we analyzed human left ventricular mechanical efficiency, applying the concept of left ventricular systolic pressure-volume area (PVA).

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“…LV-arterial coupling, which regulates SV at a given preload (51) and closely relates to LV mechanical efficiency (43), is a key determinant of optimal cardiovascular function. Previously, we demonstrated that normal-functioning LV and arterial system are nearly optimally coupled to produce SW both at rest and during exercise.…”

Section: Reversal Of the Adverse Effects Of Tachycardia On Lvarterialmentioning

confidence: 99%

Levosimendan restores the positive force-frequency relation in heart failure

Masutani

Cheng

Tachibana

et al. 2011

American Journal of Physiology-Heart and Circulatory Physiology

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Masutani S, Cheng HJ, Tachibana H, Little WC, Cheng CP. Levosimendan restores the positive force-frequency relation in heart failure. Am J Physiol Heart Circ Physiol 301: H488 -H496, 2011. First published May 13, 2011; doi:10.1152/ajpheart.01116.2010.-Frequency potentiation of contractile function is a major mechanism of the increase in myocardial performance during exercise. In heart failure (HF), this positive force-frequency relation is impaired, and the abnormal left ventricular (LV)-arterial coupling is exacerbated by tachycardia. A myofilament Ca 2ϩ sensitizer, levosimendan, has been shown to improve exercise tolerance in HF. This may be due to its beneficial actions on the force-frequency relation and LV-arterial coupling (end-systolic elastance/arterial elastance, EES/EA). We assessed the effects of therapeutic doses of levosimendan on the forcefrequency relation and EES/EA in nine conscious dogs after pacinginduced HF using pressure-volume analysis. Before HF, pacing tachycardia increased E ES, shortened , and did not impair EES/EA and mechanical efficiency (stroke work/pressure-volume area, SW/PVA). In contrast, after HF, pacing at 140, 160, 180, and 200 beat/min (bpm) produced smaller a increase of EES or less shortening of , whereas EES/EA (from 0.56 at baseline to 0.42 at 200 bpm) and SW/PVA (from 0.52 at baseline to 0.43 at 200 bpm) progressively decreased. With levosimendan, basal E ES increased 27% (6.2 mmHg/ml), decreased 11% (40.8 ms), EES/EA increased 34% (0.75), and SW/PVA improved by 15% (0.60). During tachycardia, E ES further increased by 23%, 37%, 68%, and 89%; decreased by 9%, 12%, 15%, and 17%; and EES/EA was augmented by 11%, 16%, 31%, and 33%, incrementally, with pacing rate. SW/PVA was improved (0.61 to 0.64). In conclusion, in HF, treatment with levosimendan restores the normal positive LV systolic and diastolic force-frequency relation and prevents tachycardia-induced adverse effect on LV-arterial coupling and mechanical efficiency.drugs; contractility; diastole; heart rate UNDER NORMAL CONDITIONS, an increase in heart rate (HR) augments myocardial contractility and the rate of relaxation (15,39,44). This force-frequency behavior is determined by both calcium handling and myofilament properties (26). It has been shown that the integrated dynamic balance of the intracellular Ca 2ϩ concentration ([Ca 2ϩ ] i ) is the primary cellular mechanism responsible for the force-frequency relation (FFR) and is determined by sarcoplasmic reticulum (SR) Ca 2ϩ load and Ca 2ϩ flux through the sarcolemma via L-type Ca 2ϩ channels and the Na ϩ -Ca 2ϩ exchanger (13). The positive FFR and relaxation-frequency relation (RFR) enhance cardiac performance during stress or exercise (7,36,39,44,52). In heart failure (HF), the positive FFR and RFR are impaired (16,24,28,29,44), and the abnormal left ventricular (LV)-arterial coupling is exacerbated by tachycardia. This contributes to exercise intolerance in HF (44, 52). The altered responses of LV contraction and relaxation to HR in HF may at least partially ...

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Efficiency of energy transfer from pressure-volume area to external mechanical work increases with contractile state and decreases with afterload in the left ventricle of the anesthetized closed-chest dog.

Cited by 115 publications

References 23 publications

The End-Systolic Pressure-Volume Relationship in the Newborn Lamb: Effects of Loading and Inotropic Interventions

The End-Systolic Pressure-Volume Relationship in the Newborn Lamb: Effects of Loading and Inotropic Interventions

Energy conversion efficiency in human left ventricle.

Levosimendan restores the positive force-frequency relation in heart failure

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