Can lung disease cause heart disease?
Heart disease as a consequence of lung disease is known as cor pulmonale. ‘Cor’ means related to heart and ‘pulmonale’ means related to the lungs. When there is severe lung disease, the blood vessels in the lung get destroyed or contract, increasing the blood pressure in the main blood vessels taking deoxygenated blood to the lung for oxygenation (pulmonary arteries). When the pressure in the pulmonary arteries rise (pulmonary hypertension), the strain on the right ventricle which pumps blood to the lungs increases. The right ventricular muscle gets thickened (right ventricular hypertrophy). When the load is more, the right ventricle becomes enlarged in addition to being thickened. If the lung disease is progressive, a stage may come when the right ventricle is unable to bear the extra load and may fail. When the right ventricle fails, the pressure in the right atrium increases. Walls of the right atrium gets thickened. Back pressure into the great veins which bring blood to the right atrium causes prominent distended neck veins (jugular veins). Increased pressure in the venous system of the abdomen and lower limbs cause excess fluid (edema) to collect in the lower limbs and abdomen (ascites). Increased pressure in the veins of the face give the face a congested appearance.
What are the inherited heart diseases?
The most common among the inherited heart diseases is a particular disease of the heart muscle known as hypertrophic cardiomyopathy – HCM. In hypertrophic cardiomyopathy heart muscle gets progressively thickened so that in some cases it obstructs the flow of blood from the left ventricle into the aorta (hypertrophic obstructive cardiomyopathy – HOCM). But in most cases there is no obstruction to the blood flow and it is called hypertrophic non obstructive cardiomyopathy (HNOCM). Some forms of heart muscle coming under the group of familial dilated cardiomyopathy are also inherited. In these cases, the heart muscle becomes weak and heart progressively enlarges and fails.
Another group of inherited disorders of the heart are inherited electrical disorders of the heart (cardiac ion channel disorders or cardiac channelopathies). This broad group has several disorders like long QT syndromes, short QT syndromes, Brugada syndrome and arrhythmogenic cardiomyopathy. These produce life threatening abnormalities of heart rhythm which can lead to sudden death.
Some of the birth defects of the heart (congenital heart disease) can also run in families. Some cases of atrial septal defects can be familial.
Beyond these truly genetic disorders of the heart, the most common form of heart disease in adults due to disease of the blood vessels of the heart known as coronary artery disease also has a familial predisposition. Family history of premature coronary artery disease is an important non modifiable risk factor for heart attacks.
What are the different types of heart disease?
Important types of heart diseases are congenital heart disease, rheumatic heart disease, hypertensive heart disease, ischemic heart disease and inflammatory heart disease. Congenital heart diseases are birth defects of the heart. Though they are present at birth, they need not manifest at birth. Many of them manifest only in adult life. Rheumatic heart disease is a sequelae of rheumatic fever and affects predominantly the valves of the heart, leading to valvular heart disease. Hypertensive heart disease occurs due to high blood pressure. Ischemic heart disease is due to decreased blood supply to the heart, usually as a result of partial or complete blocks in the coronary arteries which supply oxygenated blood to the heart muscle. Inflammatory heart disease could be secondary to infection or due to abnormal immune mechanisms. It can involve any of the three layers of the heart. Disease of the outer layer is known as pericarditis. Muscular part of the heart is involved in myocarditis. Inner layer is involved in endocarditis. Endocarditis is mostly infections of the heart valves which are derived from the inner layer (endocardium). Endocarditis most often occurs in valves which have been already damaged by some other disease like rheumatic heart disease. Another form of heart disease is cardiomyopathy in which heart muscle is primarily diseased. There are several varieties of cardiomyopathies or heart muscle disorders, some of which can also be inherited or run in families. Tumors though rare, can sometimes occur in the heart. Tumors of the heart are most often secondary, spreading from diseases elsewhere in the body, though primary ones are also seen occasionally.
Any of these forms of heart diseases, if severe, can lead to failure of the functions of the heart (heart failure). In addition to these different types of heart disease mentioned above, there are several disorders of the heart rhythm or electrical disorders of the heart (cardiac arrhythmia). Heart rhythm disorders can also lead to heart failure if the heart rate remains high for a long period. Heart rhythm disorders can be associated with other structural disorders of the heart listed above.