Velocity of contraction as a determinant of myocardial oxygen consumption

Sonnenblick, Edmund H.; Ross, John; Covell, James W.; Kaiser, Gerard A.; Braunwald, Eugene

doi:10.1152/ajplegacy.1965.209.5.919

Cited by 302 publications

(82 citation statements)

References 14 publications

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“…Since LVSP was positively correlated with the correct ed MVO, while TTI was negatively correlated, it is likely that tension development plays a more important role in determination of myocardial oxygen consumption than tension maintenance. The close relationship between the corrected MVO2 and Vmax in this study will support a hypothesis (Sonnenblick et al 1965) that the contractile state is one of the most important determinants. It is interesting that TTI was not positively correlated with MVO2 but negatively correlated in this study.…”

Section: Discussionsupporting

confidence: 84%

“…Starling et al (1926-27) observed a direct proportionality between MVO, and the increment in the ventricular diastolic volume. Some other indices such as TTI (Sarnoff et al 1958), LVSP multiplied by heart rate (Katz and Feinberg 1958) and velocity of contraction (Sonnenblick et al 1965) were advocated as MVO2 determinant. In this experi ment MVO2 increased in proportion to the increment of heart rate as shown in Fig.…”

Section: Discussionmentioning

confidence: 99%

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Effects of Heart Rate on Ventricular Performance, Myocardial Contractile State and Coronary Circulation

Ikeda

1974

Tohoku J. Exp. Med.

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IKEDA, S. Effects of Heart Rate on Ventricular Performance, Myocardial Contractile State and Coronary Circulation. Tohoku J. exp. Med., 1974, 112 (1), 89-100-Effects of heart rate on ventricular performance, myocardial contractile state and coronary circulation were studied under constant cardiac output in right heart by-passed anesthetized dogs. Myocardial contractile state (Vmax) was elevated as heart rate increased, and this was considered to play an important role in impeding further increase of systolic time ratio which would have occurred unless this elevation had occurred. Myocardial oxygen consumption (MV02) was mainly influenced by heart rate, left ventricular systolic peak pressure and the contractile state of the left ventricle, but neither by stroke volume of the left ventricle nor left ventricular work. After administration of propranolol, the left ventricle was deteriorated at tachycardia more than 210 beats per minute, and Vmax did not rise at such a tachycardia. These results suggest that adrenergic beta-receptor plays an important role in augmenting the contractile state of the left ventricle and in preventing it from being deteriorated at tachycardia. heart rate; myocardial contractility; coronary circulation; myocardial oxygen consumption; propranolol Bowditch (1871) reported a staircase phenomenon in the frog ventricle. That is, when the ventricle was stimulated at a constant rate, the strength of contrac tion reached a plateau, and when it was stimulated at a faster or slower rate, the strength reached a higher or lower plateau, respectively. This phenomenon was demonstrated in mammalian cardiac muscles (Woodworth 1902; Abbott and Mommaerts 1959;Blinks and Koch-Weser 1961;Sonnenblick 1962). The effects of heart rate on the intact pumping ventricle have also been examined, but the conclusions are controversial. Sarnoff et al. (1963 and Covell et al. (1967) concluded that myocardial contractility was increased as heart rate increased, while Noble et al. (1966Noble et al. ( , 1969 reported that it was not altered by changes in heart rate in conscious dogs. On the other hand, it is generally accepted that coronary circulation is influenced greatly by heart rate and ventri cular performance.This experiment was designed to ascertain whether the changes in heart rate varies the myocardial contractile state and which factors contribute to alteration of coronary blood flow and myocardial oxygen consumption. Heart rate was changed by atrial pacing, and the left ventricular pressure, its dp/dt and the total coronary venous return were measured in right heart by-passed dogs. The experiment was also performed after administration of propranolol in order to ascertain whether the activation of beta-receptor mediates the effects of heart rate on myo cardial contractile state, ventricular performance and coronary circulation. METHODEight mongrel dogs of both sexes weighing from 12 to 20 kg were anesthetized with pentobarbital sodium (30 mg/kg) given intravenously. Ventilation was provided by a positive pre...

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Section: Discussionsupporting

confidence: 84%

Section: Discussionmentioning

confidence: 99%

Effects of Heart Rate on Ventricular Performance, Myocardial Contractile State and Coronary Circulation

Ikeda

1974

Tohoku J. Exp. Med.

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“…Although the prime determinants of myocardial oxygen consumption are HR, 18 myocardial contractility, 19 and peak tension, 20 RPP is commonly used for clinical studies. [13][14][15][16][17] As an estimate of left ventricular efficiency (E), we calculated useful work (ie, CO ϫ P Ao ) and divided that product by an estimate of myocardial oxygen demand (ie, HR ϫ P Ao ϫ dP/dt max ).…”

Section: Methodsmentioning

confidence: 99%

“…Myocardial oxygen consumption (MVO 2 ) was not measured directly but was estimated by the product of heart rate (HR) and mean systemic arterial pressure (P Ao ), termed the rate-pressure-product (RPP). [13][14][15][16][17] MVO 2 ഡ HR ϫ P AoAlthough the prime determinants of myocardial oxygen consumption are HR, 18 myocardial contractility, 19 and peak tension, 20 RPP is commonly used for clinical studies. [13][14][15][16][17] As an estimate of left ventricular efficiency (E), we calculated useful work (ie, CO ϫ P Ao ) and divided that product by an estimate of myocardial oxygen demand (ie, HR ϫ P Ao ϫ dP/dt max ).…”

mentioning

confidence: 99%

Cardiovascular Effects of Intravenous Diltiazem in Dogs with Iatrogenic Atrial Fibrillation

Miyamoto

Nishijima

Nakayama

et al. 2000

Veterinary Internal Medicne

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Atrial fibrillation (AF) was induced in anesthetized Beagle hounds to determine the dose of diltiazem (D) that resulted in hemodynamic function similar to that observed during sinus rhythm (SR). Dogs were instrumented to record hemodynamic and electrophysiological parameters. Six dogs were given D, IV at cumulative doses of 0.063, 0.188, 0.438, 0.938, and 1.938 mg/kg, whereas 6 other dogs received vehicle in equivalent volumes. Plasma concentrations (PC) of D were measured. A cumulative dose of D between 0.438 and 0.938 mg/kg produced PC of 67.8 to 117.4 ng/mL and resulted in a heart rate (HR) closest to that observed during SR. At doses up to 0.938 mg/kg, no parameter of systolic function fell below that obtained during SR. At a dose of 0.938 mg/kg, the left ventricular end-diastolic and right atrial pressures exceeded those during SR. The rate-pressure product did not differ from that during SR at a dose of 0.938 mg/kg and fell below that during SR at the dose of 1.938 mg/kg. Left ventricular efficiency decreased from SR to AF, returned to values not different from those during SR at a dose of 0.938 mg/kg, and increased to values above those observed during SR at a dose of 1.938 mg/kg. In AF, slowing the HR with 0.438-0.938 mg/kg of D with resultant PC of 67.8-117.4 ng/mL results in cardiovascular function not different from that observed during SR.Key words: Cardiac efficiency; Heart rate.blocks L-type calcium channels, 1 and has proven useful in both humans 1-8 and dogs 9-12 for slowing the ventricular response in patients with atrial fibrillation (AF). Because of the dose-response relationship, it is possible to slow the ventricular rate (ie, response) to almost any degree, even to rates too low to sustain life. Although it is agreed that a ventricular rate of 250/min in a patient with AF is too fast, there is little agreement on what range of ventricular rates minimizes myocardial oxygen consumption and right atrial pressure but sustains cardiac output and systemic arterial pressure at levels appropriate for optimal performance.The purpose of this study is to report the effects of graded doses of D on parameters of cardiovascular function in dogs with AF produced by rapid atrial pacing. Our hypothesis was that D could produce a ventricular pressure (termed optimal) at which the pressure-rate product (the prime determinant of myocardial oxygen consumption) and right atrial pressure are low and systemic arterial pressure is sustained at nearly normal levels (ie, near values obtained during sinus rhythm [SR]). Such a result should optimize ventricular efficiency (ie, the ratio of useful work to myocardial oxygen consumption). Materials and MethodsTwelve, young adult, healthy Beagles of both sexes were anesthetized with thiopental (12 mg/kg IV) and ␣-chloralose a (100 mg/kg IV), and anesthesia was maintained with ␣-chloralose (30 mg/kg/h IV). Dogs were intubated and ventilated with a tidal volume of 12.5 mL/ kg (room air) and at a frequency of 12-15 breaths per minute to sustain PaCO 2 35-45 mmHg. Dogs were pl...

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“…Clearly, it would be desirable to produce the least increase in afterload consistent with adequate coronary perfusion by using low doses of these compounds and to avoid an excessive inotropic effect, since myocardial oxygen requirements are increased by positive inotropic influences at a constant level of external ventricular work.8 9 Inotropic agents, such as isoproterenol and digitalis, may also increase the aortic pressure by improving the contractility and output of the failing ventricle.…”

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confidence: 99%