Dobutamine decreases LVEDP; this contributes to which change in coronary perfusion pressure (CPP)?

Dobutamine decreases LVEDP; this contributes to which change in coronary perfusion pressure (CPP)?

• A. CPP decreases
• B. CPP unchanged
• C. CPP increases
• D. CPP depends on afterload

Answer: (C)

Coronary perfusion pressure is the driving pressure for coronary blood flow, mainly determined by the difference between diastolic aortic pressure and LV end-diastolic pressure. When dobutamine lowers LVEDP, the gradient between aortic diastolic pressure and LVEDP widens. With the aortic diastolic pressure remaining the same, a lower LVEDP increases this gradient, so CPP rises. Although heart rate may increase and diastolic time shorten, the reduced LV filling pressure tends to dominate, leading to increased CPP.

Coronary perfusion pressure is the driving pressure for coronary blood flow, mainly determined by the difference between diastolic aortic pressure and LV end-diastolic pressure. When dobutamine lowers LVEDP, the gradient between aortic diastolic pressure and LVEDP widens. With the aortic diastolic pressure remaining the same, a lower LVEDP increases this gradient, so CPP rises. Although heart rate may increase and diastolic time shorten, the reduced LV filling pressure tends to dominate, leading to increased CPP.