Question 19

College Answer

Many candidates described the pathological processes which might affect the aging heart 
rather than the physiological ones. Recognition that aging reduces cardiovascular reserve followed up with an outline of the effects of aging on the heart, the vasculature, endothelial function and the conducting system would be rewarded with a good mark.Few answers quantified the decrease of cardiac output with age and only even fewer ventured into the contribution of ventricular filling by atrial systole. No answer discussed endothelial changes with aging. Some answers were repetitious. Some answers included a significant discussion of  information that was not asked for (Laplace law/Poiseuille's law).

Discussion

• Structural changes:
  • Myocardial:
    • LV hypertrophy
    • Interventricular septal hypetrophy
    • LVOT narrowing
    • Valvular sclerosis
    • Degeneration of sympethetic innervation
  • Vascular:
    • Dilation of aorta and large arteries
    • Thickening of arterial walls
    • Decreased windkessel effect
• Functional changes:
  • Myocardial:
    • ​​​​​​​Increased systolic function
    • Decreased diastolic function
    • Increased atrial diastolic contribution (atrial "kick")
    • Decreased cardiac output (by 1% per year)
    • Decreased maximal heart rate
    • Increased cardiac workload (due to afterload increase)
    • Blunted baroreceptor reflexes
  • Electrophysiological:
    • SA node atrophy
    • Conductive tissue loss
    • Action potential prolongation
  • Vascular:
    • ​​​​​​​Decreased arterial compliance
    • Decreased endothelial NO-mediated vasodilatory function
    • Systolic blood pressure increases
    • Pulse pressure increases (diastolic pressure increases less than systolic)
    • Pulmonary arterial pressure increases
  • Neurohormonal:
    • ​​​​​​​Increased ANP secretion
    • Increased circulating catecholamine levels
    • Decreased  renin, angiotensin and aldosterone concentrations

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Ribera-Casado, J. M. "Ageing and the cardiovascular system." Zeitschrift für Gerontologie und Geriatrie 32.6 (1999): 412-419.

Ferrari, Alberto U., Alberto Radaelli, and Marco Centola. "Invited review: aging and the cardiovascular system." Journal of Applied Physiology 95.6 (2003): 2591-2597.

Karavidas, Apostolos, et al. "Aging and the cardiovascular system." Hellenic J Cardiol 51.5 (2010): 421-427.

Lam, Carolyn SP, et al. "Aortic Root Remodeling Over the Adult Life Course." Circulation 122.9 (2010): 884-890.

Lam, Carolyn SP, et al. "Age-associated increases in pulmonary artery systolic pressure in the general population." Circulation 119.20 (2009): 2663.

Ruan, Qinyun, and Sherif F. Nagueh. "Effect of age on left ventricular systolic function in humans: a study of systolic isovolumic acceleration rate." Experimental physiology 90.4 (2005): 527-534.

Brandfonbrener, Martin, MILTON LANDOWNE, and NATHAN W. SHOCK. "Changes in cardiac output with age." Circulation 12.4 (1955): 557-566.

Christou, Demetra D., and Douglas R. Seals. "Decreased maximal heart rate with aging is related to reduced β-adrenergic responsiveness but is largely explained by a reduction in intrinsic heart rate." Journal of applied physiology 105.1 (2008): 24-29.

McLean, Miriam R., Paula Bursztyn Goldberg, and Jay Roberts. "An ultrastructural study of the effects of age on sympathetic innervation and atrial tissue in the rat." Journal of molecular and cellular cardiology 15.2 (1983): 75-92.

TZUNODA, KAZUO, et al. "Effect of age on the renin-angiotensin-aldosterone system in normal subjects: simultaneous measurement of active and inactive renin, renin substrate, and aldosterone in plasma." The Journal of Clinical Endocrinology & Metabolism 62.2 (1986): 384-389.

Arora, Rohit R., et al. "Atrial kinetics and left ventricular diastolic filling in the healthy elderly." Journal of the American College of Cardiology 9.6 (1987): 1255-1260.