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Evaluation of a New Systolic Time Interval, the Q-V Peak: Effects of Heart Rate, Contractile State, and Loading Conditions in Dogs

The Third Department of Internal Medicine, Nagoya City University Medical School, Nagoya, Japan

Nobuyuki Ohte

The Third Department of Internal Medicine, Nagoya City University Medical School, Nagoya, Japan

Hitomi Narita

The Third Department of Internal Medicine, Nagoya City University Medical School, Nagoya, Japan

Kenji Kobayashi

The Third Department of Internal Medicine, Nagoya City University Medical School, Nagoya, Japan

Takao Fujinami

The Third Department of Internal Medicine, Nagoya City University Medical School, Nagoya, Japan

The authors investigated the effects of alterations in heart rate, contractility, and loading conditions on a newly defined systolic time interval, the Q-V peak, in 46 anesthetized dogs. The Q-V peak was measured as the time from the beginning of the electrocardiographic Q wave to the moment at which the blood flow rate reached its peak in the ascending aorta as determined with an electromagnetic flowmeter. The Q-V peak did not change significantly as the heart rate was varied by atrial pacing between 70 and 110 beats/minute. The Q-V peak shortened when the contractility was augmented with dobutamine (p=0.0001) and was prolonged when it was depressed with propranolol (p=0.0001). However, the Q-V peak did not change significantly when the left ventricular end-diastolic pressure or the mean aortic blood pressure was increased to 130% or decreased to 70% of the baseline values. These findings suggest that one may also evaluate left ventricular performance by measuring the time to systole, which the authors define as the Q-V peak.

Angiology, Vol. 43, No. 8, 685-692 (1992)
DOI: 10.1177/000331979204300809


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