Hemodynamic Predictors of Myocardial Oxygen Consumption During Static and Dynamic Exercise

Abstract

Hemodynamic predictors of myocardial oxygen consumption (MVO 2 ) during static and dynamic exercise were examined in ten normal subjects. Studies were done under the following circumstances: 1) during upright bicycle exercise at an average heart rate of 147 beats/min, 2) during static exercise with an isometric load in the left hand equal to 17% of the maximal voluntary contraction (MVC), and 3) during combined dynamic exercise (average heart rate 147 beats/min) and static exercise using 17% MVC of the left hand. Mean myocardial blood flow (MBF) was 181 ml/100 gm LV/min during dynamic exercise, 98 ml/100 gm LV/min during static exercise, and 201 ml/100 gm LV/min during combined static and dynamic exercise. Addition of a static load to the dynamic load resulted in a higher blood pressure (average 12 mm Hg), MVO 2 and MBF than during dynamic exercise alone. MVO 2 correlated best with products of heart rate and blood pressure regardless of whether the blood pressure was obtained by a central aortic catheter ( r = 0.88) or by a blood pressure cuff ( r = 0.85). When the current data were combined with previous data, 82 determinations of MVO 2 and MBF in 29 normal subjects during several levels of upright exercise were available for analysis. Forty-four determinations were done during dynamic upright exercise, 18 during exercise after propranolol, ten during combined static and dynamic work, and ten during static work alone. MVO 2 correlated best with the product of heart rate and blood pressure ( r = 0.86). Heart rate alone correlated better with MVO 2 ( r = 0.82) than did the tension time index ( r = 0.65) or the product of systolic blood pressure, heart rate, and ejection time ( r = 0.68). The readily measured variables of heart rate and of heart rate x blood pressure correlated well with MVO 2 in normal young men during exercise under a wide variety of circumstances.

[11C]Acetate rest–stress protocol to assess myocardial perfusion and oxygen consumption reserve in a model of congestive heart failure in rats

“…We noticed that either positive or negative stimulation of the beta-adrenergic receptor led to a decrease in mean systemic blood pressure, although with dobutamine, this effect did not reach statistical significance (p = 0.08). Nevertheless, the RPP, which is known to be well correlated with the oxygen consumption [23], was found to hold true even when the blood pressure was decreased through pharmacological manipulation. In the current study, we were therefore able to confirm the relationship between the RPP and myocardial oxygen consumption.…”

“…Among the various parameters that have been proposed to measure the oxygen demand in healthy subjects [8], the heart rate-pressure product (RPP) (heart rate × systolic pressure) is recognized to be a good index of MVO 2 [8,[21][22][23]. In the validation experiment, we were able to calculate the RPP using the heart rate and the measurements of the systolic pressure obtained with the arterial pressure analyzer.…”

<b>Comparison of Cardiovascular Responses to Isometric (Static) and Isotonic (Dynamic) Exercise Tests in Chronic Atrial Fibrillation</b>

“…20) Hornsten and Bruce 20) demonstrated that 74% of the total variation in HR was at the first stage of exercise in AF patients. Other studies 8,[17][18][19][20] have found that the increase in HR was maximal at the lowest stage of workload (for example: at 3.0 mph, 0% grade, and under anaerobic conditions) compared to the values at rest; and that less of an increase in HR compared to the first increase occurred at the maximal stage. Therefore, they reported that exercise tests can be used to evaluate the activities of pharmacologic agents for controlling HR in AF patients.…”

“…HR increases directly proportional to oxygen uptake and the applied workload. 3) It has been reported that a rapid ventricle response beyond normal was seen at the first stage of static exercise in AF patients 8,[17][18][19] and that this response was higher than in normal subjects. 20) Hornsten and Bruce 20) demonstrated that 74% of the total variation in HR was at the first stage of exercise in AF patients.…”

Comparison of cardiovascular response to combined static-dynamic effort, postprandial dynamic effort and dynamic effort alone in patients with chronic ischemic heart disease.

“…Neither the extent of STsegment depression nor the attainment of a target heart rate was used as an end point. Maximal voluntary contraction (MVC) for handgrip was determined in the right hand using a Jaymar hand dynamometer 15 mCi of technetium-99m labeled to human serum albumin was injected 2 hours later.…”