Effect of tachycardia on left ventricular blood flow distribution during coronary occlusion

Research output: Contribution to journalArticlepeer-review

Abstract

The effect of heart rate on the amount and distribution of collateral blood flow was determined in open chested dogs 1 h after coronary artery ligation. Flows to ischemic and nonischemic regions of left ventricle were measured with 7 to 10 μm diam radioactive microspheres during base line conditions (118 ± 6 beats/min) and again during atrial pacing at rates 20 and 40% above control (141 ± 7 and 165 ± 9 beats/min). During pacing aortic and left atrial pressures and cardiac output did not change significantly, whereas ST segment elevation in epicardial electrograms increased markedly. In nonischemic myocardium, mean flow increased approximately in proportion to the increase in rate, but subepicardial (EPI) flow increased somewhat more than subendocardial (ENDO) flow. In ischemic myocardium, overall flow did not change significantly, but a redistribution from ENDO to EPI was seen. At the faster rate ENDO flow fell 25% (P < 0.02), EPI flow increased slightly, and ENDO/EPI fell in 8/9 animals (mean 0.54-0.43, P<0.01). The ENDO/EPI maldistribution present in ischemic muscle is thus accentuated by tachycardia; this may account for part of the harmful effect of tachycardia in acute myocardial infarction and may help explain the disproportionate ENDO ischemia seen in angina pectoris.

Original languageEnglish (US)
Pages (from-to)1072-1077
Number of pages6
JournalAmerican Journal of Physiology
Volume230
Issue number4
StatePublished - Dec 1 1976
Externally publishedYes

ASJC Scopus subject areas

  • Physiology (medical)

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