Pathophysiology of Cardiac Performance

Cardiac performance depends on the heart rate, heart rhythm, myocardial contraction, and blood flow.

The heart's rate and rhythm are regulated by a specialized conducting system. They coordinate synchronized contractions through cardiomyocytes via voltage-sensitive channels.

Abnormalities in this system, like myocardial damage, conducting system defects, or increased sympathetic activity, can result in arrhythmias.

Within the cardiac muscles, the interaction of actin and myosin filaments triggers myocardial contraction, enabling the heart to pump blood.

The force of this contraction determines the cardiac output, which is the product of the heart rate and the mean ventricular stroke volume. It is influenced by the intrinsic contractility, preload —cardiac filling pressure, and afterload—the peripheral resistance during blood pumping.

Myocardial ischemia and cardiomyopathies can impair contractility, increasing cardiac workload and oxygen consumption.

Myocardial oxygen consumption relies on coronary blood flow, which is regulated by various physiological factors.

Conditions such as atherosclerosis and hormonal or metabolic responses to stress may reduce coronary flow, leading to ischemia or angina.