Introduction
Aging causes a progressive decline in various physiological processes of the body, resulting in health risks and diseases. It has a remarkable effect on the cardiovascular system, leading to an increased risk of cardiovascular diseases such as atherosclerosis, hypertension, stroke, and myocardial infarction. The term cardiovascular aging refers to not only the passage of time but also the challenging factors that drive the aging of the heart and its blood vessels.
What Is Cardiovascular Aging?
Age is a major determinant of a person’s cardiovascular health. Cardiovascular aging is a complex process that is associated with a decline in the structure and functions of the heart. The age-related structural and functional changes progress to cause cardiovascular diseases. Time-dependent changes in the cardiovascular system are aggravated by risk factors such as smoking, hypertension, and diabetes. Aging and other risk factors are responsible for causing cardiovascular diseases such as coronary artery disease, hypertension, atherosclerosis, atrial fibrillation, myocardial infarction, heart failure, stroke, and cardiovascular death.
What Are the Structural and Functional Changes in the Heart During Cardiovascular Aging?
-
Cardiovascular aging is associated with the thickening of the left ventricular wall and myocardial fibrosis due to excessive accumulation of collagen. Cardiac hypertrophy and fibrosis result in myocardial stiffening. An increase in left ventricular stiffness contributes to left atrial enlargement and a decline in diastolic function. It also slows the conduction of electric impulses throughout the heart.
-
Cardiovascular aging also causes a reduction in maximum ejection fraction and maximal heart rate resulting in a diminished maximal cardiac output. The compromised cardiac reserve capacity causes a reduction in peak oxygen consumption, thereby reducing the quality of life in the elderly.
-
As a result of aging, fibrous tissues and fat deposit in the pathways of the cardiac conduction system, and the sinoatrial node, a natural pacemaker of the heart which controls the heartbeat, loses some of its cells. These changes result in a slower heart rate.
-
Despite the increase in the size of the heart, the reserve capacity of the heart decreases due to the thickening of the heart wall. This causes slow ventricular filling.
-
Cardiovascular aging causes changes in the ECG (electrocardiogram). Abnormal rhythms, such as atrial fibrillation, are commonly seen in elderly people.
-
As a result of aging, a pigment called lipofuscin gets deposited in the heart. The cells in the heart muscle degenerate, and the valves become thicker and stiffer. The valve stiffness causes heart murmur, which is common in older people.
What Are the Structural and Functional Changes in the Cardiac Vessels During Cardiovascular Aging?
-
The lumina and the walls of the large vessels, such as the aorta and common carotid arteries, thicken as a result of aging. It is also associated with endothelial dysfunction. These changes contribute to an increase in the stiffness of central arteries and pulse wave velocity.
-
The aorta becomes thick and stiff due to changes in the connective tissue in the walls of the blood vessels. This increases blood pressure and makes the heart work hard, resulting in hypertrophy (thickening) of the heart muscle. The other vessels also thicken and stiffen, causing a moderate increase in blood pressure in elderly people.
-
Baroreceptors are located within the walls of the carotid sinus and the aortic arch. They sense changes in blood pressure and help in maintaining fairly constant blood pressure during activities or changes in position. These baroreceptors become less sensitive due to aging, and this causes orthostatic hypotension in older people. This is the reason for dizziness when a person stands from a lying or sitting position.
What Are the Pathological Features of Cardiovascular Aging?
The pathological changes associated with cardiovascular aging are luminal dilation, endothelial dysfunction, increased arterial stiffness, and intimal thickening. The central aorta and the carotid arteries are elastic, and they dilate with age, causing an increase in the lumen diameter. Cardiovascular aging also causes progressive thickening of the vasculature resulting in stiffness. Increased stiffness can be due to increased elastin degradation and collagen deposition in the media of the blood vessels. Endothelial dysfunction in aged vessels aggravates the thickening and fibrosis of the vessels. This increases vascular permeability and inflammation and leads to impaired angiogenesis.
The calcification of aortic and mitral valves is another important pathological change associated with cardiovascular aging. This causes stenosis or insufficiency resulting in increased pressure and volume overload. Myocardial fibrosis and stiffness impair left ventricular compliance causing a decline in systolic and diastolic function. Cardiovascular aging is also associated with decreased presence of collaterals to the infarct-related arteries in myocardial infarction. This contributes to poor prognosis in older patients with acute coronary syndromes.
What Are the Cardiovascular Diseases Associated With Cardiovascular Aging?
The following cardiovascular diseases are associated with cardiovascular aging:
-
Arrhythmias - Abnormal heart rhythms, such as atrial fibrillation, are common in older people.
-
Angina - Chest pain occurs due to a temporary reduction in blood flow to the heart muscles. Heart failure and shortness of breath can result from coronary artery disease.
-
Coronary Artery Disease - It is a common cardiovascular disease in elderly people, which occurs as a result of atherosclerosis.
-
Atherosclerosis - It is a condition in which the arteries harden due to fatty deposits and plaque formation inside the blood vessels, resulting in narrowing and blockage of the blood vessels.
-
Congestive Heart Failure - It is a chronic condition in which the pumping function of the heart is affected, resulting in heart failure.
-
Aortic stenosis (narrowing of the heart valve) and heart valve diseases are common in older people.
-
Transient ischemic attack or stroke occurs if the blood flow to the brain is affected.
-
High blood pressure and orthostatic hypotension (low blood pressure due to standing after sitting or lying down) are also common in older people.
-
Aging can also cause disorders like blood clots, thrombophlebitis (inflammation of the wall of a vein), deep vein thrombosis (a blood clot that forms in a vein deep inside), varicose veins (swollen, twisted, and enlarged veins under the skin), peripheral vascular disease, and aneurysms (widening or ballooning of a part of an artery).
Conclusion
Cardiovascular aging is an unavoidable phenomenon. Various molecular mechanisms take part in cardiovascular aging. It is not just time-dependent changes, and various risk factors also contribute to cardiovascular aging. Maintaining a healthy diet and a metabolic profile can help slow the process of cardiovascular aging.
