A healthy 80-year-old man has participated in a longitudinal study over the past 30 years to study the effects of aging on overall cardiovascular status. He has undergone annual testing with echocardiography and his left ventricular ejection fraction has remained stable throughout the 30 years. Which of the following changes is most likely responsible for the preserved left ventricular ejection fraction in this patient?

Question

A healthy 80-year-old man has participated in a longitudinal study over the past 30 years to study the effects of aging on overall cardiovascular status.  He has undergone annual testing with echocardiography and his left ventricular ejection fraction has remained stable throughout the 30 years.  Which of the following changes is most likely responsible for the preserved left ventricular ejection fraction in this patient?

Quizplus · Accepted Answer

11ec160b_3c83_e1c7_9249_13b218e4aeb4_MD0001_00 The cardiovascular system undergoes an array of age-related physiologic changes. Over time, cardiomyocytes are lost to both apoptosis and necrosis (ie, cardiomyocyte dropout), resulting in an overall reduced cardiomyocyte number. The loss of ventricular cardiomyocytes (Choice E) weakens contractile strength. In addition, the aorta and other large arteries stiffen with age, resulting in reduced arterial compliance (ie, reduced arterial reserve capacity) (Choice B) and increased left ventricular (LV) afterload. To compensate for the cardiomyocyte loss and increased afterload, cardiomyocyte hypertrophy (ie, mild concentric LV hypertrophy) occurs, allowing for maintenance of LV contractility and ejection fraction. Cardiomyocyte dropout also affects cardiac conduction cells, contributing to decreased maximal heart rate and slightly decreased resting heart rate. Decreased responsiveness to adrenergic stimuli with age also contributes to reduced maximal heart rate. (Choices C and D) The mild concentric LV hypertrophy that occurs with age results in reductions in LV compliance and LV end-diastolic volume. However, because these changes are relatively slight, stroke volume and cardiac output are mostly preserved. Educational objective: Cardiomyocyte hypertrophy (ie, concentric left ventricular hypertrophy) occurs with age to allow for maintenance of left ventricular contractility and ejection fraction despite cardiomyocyte dropout and increased left ventricular afterload (due to reduced aortic compliance).

A Healthy 80-Year-Old Man Has Participated in a Longitudinal Study