Aging: Cardiovascular physiology


It is important to distinguish between changes in physiology that normally accompany aging and the pathophysiology of diseases common in the geriatric population. For example, atherosclerosis is pathological: it is not present in healthy elderly patients. On the other hand, a reduction in arterial elasticity caused by fibrosis of the media is part of the normal aging process. Reduced arterial compliance results in increased afterload, elevated systolic blood pressure, and left ventricular hypertrophy. The left ventricular wall thickens at the expense of the left ventricular cavity. Some myocardial fibrosis and calcification of the valves are common. In the absence of coexisting disease, diastolic blood pressure remains unchanged or decreases. Baroreceptor function is depressed. Similarly, whereas cardiac output typically declines with age, it appears to be maintained in well-conditioned healthy individuals. In the absence of disease, resting systolic cardiac function appears to be preserved even in octogenarians. Vagal outflow decreases with age, which may limit the ability of anticholinergics to increase heart rate.  Maximal heart rate declines by approximately one beat per minute per year of age over 50. Fibrosis of the conduction system and loss of sinoatrial node cells increase the incidence of dysrhythmias, particularly atrial fibrillation and flutter.

Elderly patients undergoing evaluation for surgery have a high incidence of diastolic dysfunction that can be detected with Doppler echocardiography. Marked diastolic dysfunction may be seen with systemic hypertension, coronary artery disease, cardiomyopathies, and valvular heart disease, particularly aortic stenosis. Patients may be asymptomatic or complain of exercise intolerance, dyspnea, cough, or fatigue. Diastolic dysfunction results in relatively large increases in ventricular end-diastolic pressure with small changes of left ventricular volume; the atrial contribution to ventricular filling becomes even more important than in younger patients. Atrial enlargement predisposes patients to atrial fibrillation and flutter. Patients are at increased risk for developing congestive heart failure.

Diminished cardiac reserve in many elderly patients may be manifested as exaggerated drops in blood pressure during induction of general anesthesia. A prolonged circulation time delays the onset of intravenous drugs but speeds induction with inhalational agents. Like infants, elderly patients have less ability to respond to hypovolemia, hypotension, or hypoxia with an increase in heart rate.



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Cardiovascular effects of aging