Author(s)

Jacques R. Rouleau, Bernard Cantin, John G. Kingma Jr

Institut universitaire de cardiologie et de pneumologie de Québec-Université Laval 2725, Chemin Ste-Foy, Ste-Foy (Quebec) Canada.

Changes in intramyocardial tissue pressure modulate the relationship between coronary pressure and flow during the cardiac cycle. The present study compared the relation between measured and calculated diastolic subendocardial tissue pressure and coronary pressure at zero flow in anesthetized dogs after modulation of either coronary sinus (i.e. Fogarty catheter) or left ventricular intracavity (i.e. volume loading) pressure. Experiments were conducted in anesthetized, instrumented dogs; coronary pressure flow relations were constructed during pharmacologic vasodilatation and intramyocardial tissue pressure was measured using micromanometer pressure sensors. Elevated coronary sinus pressures did not affect subendocardial pressure-flow relations signifying that diastolic tissue pressure within this layer is the effective coronary back pressure. Higher left ventricular intracavity pressure did not affect either diastolic subendocardial tissue pressure or pressure flow relations within this layer. Results show a direct linear relation (y = 1.106x - 0.652; r² = 0.59. P = 0.001) between measured and calculated diastolic subendocardial tissue pressure and coronary pressure at zero-flow over a wide range of pressures after either LV systemic or coronary sinus pressure modulation. Knowledge of back pressure in the subendocardium is useful for the evaluation of efficacy of cardiac interventions on myocardial perfusion particularly at the level of the microcirculation.

Intramyocardial Tissue Pressure, Pressure-Flow Relations, Transmural Myocardial Blood Flow, Microspheres, Coronary Sinus Pressure, Volume Overload

Rouleau, J. , Cantin, B. and Kingma Jr, J. (2017) Comparison between Diastolic Subendocardial Tissue Pressures Measured Directly or Calculated from Pressure-Flow Relations. World Journal of Cardiovascular Diseases, 7, 213-224. doi: 10.4236/wjcd.2017.77020.