Chapter 19: heart failure and dysrhythmias: common sequelae of cardiac diseases. Hf is a potential consequence of most cardiac disorders. Hf occurs when the heart is unable to provide sufficient cardiac output to meet normal metabolic functions of the body. The most common cause of hf is myocardial ischemia from coronary artery disease, followed by hypertension and dilated cardiomyopathy. Impaired contractility resulting in systolic failure is frequently associated with hf. The biochemical basis of impaired contractility involves loss of cardiac muscle cells, -receptor down-regulation, and reduced atp production. In about half of hf patients, systolic function is preserved and diastolic dysfunction predominates. Hf with normal ef is particularly likely to develop in the elderly, in women, and in those without history of mi. Left ventricular pressure-volume loops characterize the differences in systolic and diastolic dysfunction. High diastolic volume and reduced ef indicate systolic failure, whereas diastolic failure is characterized by higher diastolic pressure and low volume.