A number of changes occur in the neck vessels, cardiac output, heart sounds, and murmurs.
1. Neck Vessels
Lengthening and tortuosity of the aorta and its branches occasionally result in kinking or buckling of the carotid artery low in the neck, especially on the right. The resulting pulsatile mass, occurring chiefly in women with hypertension, may be mistaken for a carotid aneurysm—a true dilatation of the artery. A tortuous aorta occasionally raises the pressure in the jugular veins on the left side of the neck by impairing their drainage within the thorax.
In older adults, systolic bruits heard in the middle or upper portions of the carotid arteries indicate stenosis from atherosclerotic plaque. Cervical bruits in younger people are usually innocent.
2. Cardiac Output
Myocardial contraction is less responsive to stimulation from β-adrenergic catecholamines. There is a modest drop in resting heart rate, but a significant drop in the maximum heart rate during exercise. Although heart rate drops, stroke volume increases, so cardiac output is maintained. Diastolic dysfunction arises from decreased early diastolic filling and greater dependence on atrial contraction. There is increased myocardial stiffness, notably in the left ventricle, which also hypertrophies.
Risk of heart failure increases with loss of atrial contraction and onset of atrial fibrillation due to decreased ventricular filling.
3. Extra Heart Sounds—S3 and S4
A physiologic third heart sound, commonly heard in children and young adults, may persist as late as age 40 years, especially in women. After age 40 years, however, an S3 strongly suggests heart failure from volume overload of the left ventricle in conditions like heart failure and valvular heart disease (e.g., mitral regurgitation). In contrast, a fourth heart sound is seldom heard in young adults other than wellconditioned athletes. An S4 can be heard in otherwise healthy older people, but often suggests decreased ventricular compliance and impaired ventricular filling.
4. Cardiac Murmurs
Middle-aged and older adults commonly have a systolic aortic murmur. This murmur is detected in approximately one third of
people at age 60 years, and in more than half of those reaching 85 years. With aging, fibrotic changes thicken the bases of the aortic cusps. Calcification follows, resulting in audible vibrations. Turbulence produced by blood flow into a dilated aorta may further augment this murmur. In most older adults, the process of fibrosis and calcification, known as aortic sclerosis, does not impede blood flow. In some, the aortic valve leaflets become calcified and immobile, resulting in aortic stenosis and outflow obstruction. A brisk carotid upstroke can help distinguish aortic sclerosis from aortic stenosis, which has a delayed carotid upstroke, but clinically distinguishing these conditions is difficult. Both carry increased risk for cardiovascular morbidity and mortality.
Similar changes alter the mitral valve, but usually about one decade later than the aortic valve. Calcification of the mitral valve annulus, or valve ring, impedes normal valve closure during systole, causing the systolic murmur of mitral regurgitation. This change in the configuration of the valve may become pathologic as volume overload increases in the left ventricle.
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