Coronary transport reserve in normal dogs

Area of Science:

• Cardiovascular Physiology
• Pharmacology
• Medical Imaging

Background:

• Accurate quantification of coronary blood flow (CBF) reserve and coronary capillary transport reserve requires a reliable method for achieving maximal coronary vasodilation.
• Previous methods may lack reproducibility or cause significant physiological disturbances.

Purpose of the Study:

• To determine an optimal method for inducing maximal coronary vasodilation for the assessment of coronary blood flow and capillary transport reserve.
• To evaluate the efficacy and reproducibility of adenosine (ADO) for achieving maximal vasodilation.

Main Methods:

• Anesthetized dogs underwent cannulation and pump-perfusion of the left anterior descending coronary artery.
• Continuous monitoring of hemodynamic parameters, ECG, blood gases, and CBF.
• Maximal vasodilation was induced using various agents including adenosine, dipyridamole, and papaverine.
• Myocardial extraction and permeability-surface area products (PS) were measured using the single-injection indicator-diffusion method.

Main Results:

• Adenosine (ADO) was selected as the optimal agent due to reproducible maximal CBF and PS, with minimal cardiovascular effects.
• Baseline PS averaged 20 +/- 2 ml x min-1 x 100 g-1 and showed no relationship with perfusion pressure.
• During maximal vasodilation, CBF and PS increased linearly with perfusion pressure.
• Constant pressure maximal vasodilation with ADO increased PS to 36 +/- 4 ml x min-1 x 100 g-1 and CBF by 380%.

Conclusions:

• Adenosine is a suitable agent for inducing reproducible maximal coronary vasodilation.
• Maximal vasodilation significantly enhances coronary capillary transport, demonstrating a linear relationship with coronary perfusion pressure and plasma flow.
• This method provides a reliable approach for quantifying coronary blood flow and capillary transport reserves.