Coronary vasodilation after a single ventricular extra-activation in the conscious dog.


Journal Article

This study was undertaken to determine if coronary blood flow can be regulated in response to a transient increase in cardiac metabolic demand. Eight conscious dogs with experimentally produced complete heart block, a chronically implanted electromagnetic flow probe on the left circumflex coronary artery, and fluid-filled catheters for measurement of left ventricular and aortic pressures were studied. At a paced heart rate of 60 beats/min, a single ventricular extra-stimulus was introduced with a delay of 150-200 msec from the preceding R-wave. The extra-stimulus produced a ventricular extra-activation, but not a discrete mechanical extra-systole. The ensuing beats exhibited systolic potentiation, manifest by a 50 +/- 8% increase from control in maximum left ventricular dp/dt in the first potentiated beat, presumably accompanied by increased myocardial oxygen demand. In the diastole immediately following the first potentiated systole, the coronary vascular resistance index (mean aortic pressure/mean coronary flow in that diastole) fell significantly from control by 12 +/- 2%. The results indicate that a transient increase in cardiac metabolic demand is followed immediately by a compensatory coronary vasodilation that occurs within the same cardiac cycle.

Full Text

Duke Authors

Cited Authors

  • Schwartz, GG; McHale, PA; Greenfield, JC

Published Date

  • January 1, 1982

Published In

Volume / Issue

  • 50 / 1

Start / End Page

  • 38 - 46

PubMed ID

  • 7053876

Pubmed Central ID

  • 7053876

International Standard Serial Number (ISSN)

  • 0009-7330

Digital Object Identifier (DOI)

  • 10.1161/01.res.50.1.38


  • eng

Conference Location

  • United States