Myocardial Infarction & Peripheral Vascular Diseases Q 5

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An older, sedentary adult may not respond to emotional or physical stress as well as a younger individual because of:

  

     A. Left ventricular atrophy

     B. Irregular heartbeats

     C. Peripheral vascular occlusion

     D. Pacemaker placement

    

    

Correct Answer: A. Left ventricular atrophy

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In older adults who are less active and do not exercise the heart muscle, atrophy can result. Disuse or deconditioning can lead to abnormal changes in the myocardium of the older adult. As a result, under sudden emotional or physical stress, the left ventricle is less able to respond to the increased demands on the myocardial muscle. While aging does not itself cause heart failure (HF), it does lower the threshold for the manifestation of the disease. As the populations of most developed countries continue to become older, on average, the importance of aging as a risk factor for all cardiovascular diseases increases in kind.

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Option B: There are a number of functional changes and compensatory responses that the aged heart undergoes that diminish its ability to respond to increased workload and decrease its reserve capacity. Changes in maximal heart rate, end-systolic volume (ESV), end-diastolic volume (EDV), contractility, prolonged systolic contraction, prolonged diastolic relaxation, sympathetic signaling, etc.

Option C: There is a progressive increase in the prevalence of cardiovascular disease (CVD); e.g. coronary artery disease (CAD), hypertension, and diabetes leading to the development of ischemic, hypertensive, or diabetic cardiomyopathy. Autopsy reports published as early as 1910 described age-associated aortic thickening. Cross-sectional studies using ultrasound imaging have demonstrated the intimal-medial layer thickens nearly threefold between the ages of 20 and 90 years in apparently healthy individuals.

Option D: Aging is associated with a generalized increase in elastic and collagenous tissue. Fat accumulates around the sinoatrial node, sometimes creating a partial or complete separation of the node from the atrial tissue. A pronounced decline in the number of pacemaker cells occurs after age 60; by age 75 less than 10% of the number seen in young adults remains.

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