Energetics of the human heart∗

Levine, Herbert J.; Wagman, Richard J.

doi:10.1016/0002-9149(62)90155-8

Cited by 98 publications

(10 citation statements)

References 47 publications

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“…If diastolic volumes were the same or smaller in CH than SH, this implies that the extent of fiber shortening during contraction must also have been greater in CH (25). When atrial pressure was increased the occompanying rises in cardiac output and cardiac work in both CH and SH were proportionately greater than changes in myocardial oxygen consumption, and calculated efficiency increased significantly.…”

Section: Discussionmentioning

confidence: 99%

The effect of physical training upon the mechanical and metabolic performance of the rat heart

Penpargkul¹,

Scheuer²

1970

J. Clin. Invest.

112

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A B S T R A C T The dynamic and metabolic performance of rats conditioned by a swimming program (CH) and hearts of sedentary rats (SH) was studied in an isolated working rat heart apparatus. Heart rate, filling pressure, and afterload were controlled or kept constant, and heart weights were comparable in both groups.When compared with SH, CH had increased cardiac output and cardiac work. Atrial pacing at more rapid rates caused greater differences in these functions, and left ventricular pressure and maximal rate of pressure rise (dp/dt) became higher in CH than in SH. Atrial pacing was associated in CH with increased oxygen consumption but in SH by increased lactate and pyruvate production.When atrial filling pressure was elevated in order to perform ventricular function curves, CH showed greater dynamic responses than SH. There were also greater increments in oxygen consumption, and the ratio of aerobic to anaerobic energy production was also higher in CH.The mechanism of increasing oxygen consumption during stress in CH was mainly by improved coronary flow. In SH coronary flow did not change, but extraction of oxygen from the perfusing fluid increased.The results indicate that in physically trained rats the function of the heart as a pump is improved. These hearts have greater aerobic and mechanical reserve than hearts of sedentary animals. These effects appear to be at least partially due to improved mechanisms of oxygen delivery.

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Section: Discussionmentioning

confidence: 99%

The effect of physical training upon the mechanical and metabolic performance of the rat heart

Penpargkul¹,

Scheuer²

1970

J. Clin. Invest.

112

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“…To develop a given systolic pressure, a large EDV necessitates a large increase in the force of contraction by the ventricular muscle (17), simply to produce the same or even a smaller forward flow. The disadvantage for ventricular function can be enormous, and myocardial oxygen needs will be increased (18).…”

Section: Discussionmentioning

confidence: 99%

Left Ventricular Volume Measurements in Man by Thermodilution*

Bristow¹,

Crislip²,

Farrehi³

et al. 1964

J. Clin. Invest.

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A safe, rapid method for estimating left ventricular volume in man during the course of hemodynamic studies should prove helpful in the assessment of cardiac disease and useful in physiological research. It is the purpose of this report to present left ventricular volume measurements in man that were obtained by an indicator dilution method which employs cold as the indicator. This circulatory indicator has been studied by several workers (1-4) and has been used for left ventricular volume determinations in animals previously (5-10). The method employed was adapted from those used by Rapaport and his co-workers for left ventricular volume measurements in the dog (7) and right ventricular studies in man (11). MethodsThirty-eight patients were studied during diagnostic left heart catheterization. The left ventricle was catheterized by the percutaneous transseptal method, utilizing a Teflon catheter which has four side holes near its tip (12). Left atrial pressure was measured before and after ventricular catheterization. A brachial artery was cannulated percutaneously with a 15-cm length of polyethylene tubing. A 6F Teflon catheter was introduced percutaneously into the right femoral artery and advanced until its tip was slightly above the aortic valve, as judged fluoroscopically. Left heart pressures were measured with a P-23G strain gage' and systemic arterial pressure with a P-23D gage.' These pressures and the electrocardiogram were recorded with a direct-writing four channel oscillograph. system and that it present an exponential series of decreasing, steplike concentrations. In these studies cold was used as the indicator and was delivered rapidly into the left ventricle by injections of 5 ml of cooled saline. Rarely, 10-to 15-ml injections were given in patients with extremely large ventricular volumes. A bead thermistor in the proximal aorta served as the sampling system. The thermistor catheter was of nylon (o. d., 0.97 mm) with a closed end and had a rapidly responding thermistor bead mounted at its tip.3 This catheter was 1 cm longer than the radiopaque aortic catheter and was inserted into the latter when thermodilution curves were to be recorded. This placed the thermistor into the blood stream just above the aortic valve. Immediately after recording the thermodilution curves and cardiac output by dye dilution, the aortic catheters were removed to avoid the possibility of thrombosis.The thermistor was employed as one arm of a Wheatstone bridge that was activated by a mercury battery. Approximately 0.1 v was presented to the thermistor itself. The resulting signal was amplified by a type 53/54 D preamplifier4 and displayed with a type RM 565 oscilloscope.4 The electrocardiogram was displayed simultaneously by a type 3 A 74 amplifying electronic switch.4 Records were made by photographing the oscilloscope screen with 35-mm film.The thermistors were calibrated against known temperature in a water bath. The peak change in aortic blood temperature produced by the cold inj ections was usually between 0.3°an...

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“…This measure of pressure and time (hereafter referred to as pressure-time per minute), however, did not bear a constant relation to oxygen consumption during exercise in normal human subjects (10). As changes in ventricular dimensions during exercise had been reported (11), it was suggested that changes in radius and therefore of wall tension may have been responsible for the observed discrepancy between pressure-time per minute and oxygen consumption (10). Subsequently, oxygen consumption has been related to the product of mean myocardial tensile force and the systolic ejection period (force-time per minute).…”

mentioning

confidence: 90%

“…To estimate the dF/dl of the dog's left ventricle, the relationship between dF/dl and F in the cat papillary muscle was normalized for unit dimensions and extrapolated to the specific dimensions of each dog's left ventricle. This formula, which was derived in the preceding paper (15) 10, the muscle length, was obtained as 27rr, where r0 is the smallest end-diastolic chamber radius measured in a given dog, and A0, the cross-sectional area of muscle, was derived as 27rrot, where t is the wall thickness at that end-diastolic chamber size. The smallest end-diastolic chamber size was used to approximate the resting dimensions of the muscle.…”

mentioning

confidence: 99%