Problems of bronchitis and chronic cough are seen frequently in our elderly population, though younger population is not immune from This can affect the heart and in advanced cases lead to heart failure which can progress to severe desaturation of blood with oximeter showing saturation as low as 60 to 65%, which is dangerously low and can be fatal if not managed with oxygen treatment using a mask or nasal prongs. The lips, tongue and nail beds often become blue.
How does lung disease affect the heart?
The teamwork of the heart and lungs ensures that the body has a constant supply of oxygen for metabolic activities and that the major waste product of metabolism, carbon dioxide, is continuously removed. This occurs through the circulation of lungs, with the heart supplying blood that has moved through the body to the lungs. The heart and lungs work together to deliver oxygen to and remove carbon dioxide from the body’s tissues.
When you inhale, oxygen enters the blood via little sacs in the lungs called alveoli. The oxygenated blood travels through the pulmonary veins to the left side of the heart, where it is pumped throughout the body. The deoxygenated blood then returns to the right side of the heart and is pumped through the pulmonary arteries to the lungs. When you exhale, carbon dioxide exits your body and the cycle starts again.
But this process can go wrong in people with lung diseases. Low oxygen levels in the alveoli cause the arteries of the lungs to constrict (narrow) and the normally low pressure in the arteries to rise. If the pressure in the pulmonary arteries rises to a sufficiently high level, a condition called secondary pulmonary hypertension (high blood pressure in lung arteries) develops. In pulmonary hypertension, the right side of the heart must work harder to push blood through the pulmonary arteries into the lungs. Over time, the heart’s right ventricle becomes thick and enlarged and the heart’s pumping action may deteriorate. The result of this damage may be heart failure. Heart failure because of lung diseases is also called “Cor Pulmonale”. This is often due to chronic lung problems and is a significant cause of morbidity and mortality and needs vigil and timely management. The consequences are very serious with a very high mortality.
The common causes of Chronic Cor Pulmonale in our setting are:
1. chronic obstructive lung disease, due to chronic bronchitis seen often in smokers often called winter bronchitis 2. Uncontrolled persistent asthma 3. Interstitial lung disease. 4. Obstructive sleep apnea (OSA) , a problem seen in obese persons who have sleep disorders and snore a lot during sleep.
Diagnosis of this condition at times needs a thorough history and clinical examination. The common symptoms are shortness of breath occurring on exertion and in later stages even at rest. Wheezing, chronic wet cough, swelling of feet, ankles and later abdomen with fluid accumulation are common associations. Other features seen along with these features are the enlargement of neck veins and facial veins, enlargement of liver due to congestion with bluish discolouration of skin.
X Ray chest showing telltale shadows of lung damage or increased air trapped called emphysematous changes. This is often associated with shadows of enlarged arteries of the lungs and right side of the heart.
ECG is also a useful investigation which can show signs of increased thickness and enlargement of right sided chambers of the heart.
Echocardiography is a very useful investigation which can visualize the enlarged right sided chambers of the heart and the Doppler study actually measures the elevated pressures and often shows leakage of the tricuspid valve. CT Scan of the chest is often prescribed to visualize the lung structure and document the abnormalities which can be diagnostic.
Elimination of the cause is the most important intervention. Smoking must be completely stopped, exposure to dust, flames, household smoke and to cold weather is avoided. If there is evidence of respiratory infection, it should be treated with appropriate antibiotics. Diuretics (Water pills) for removing excessive fluid help in relieving the symptoms of congestion. Many patients additionally need blood thinners to prevent strokes due to abnormal heart rhythm like atrial fibrillation.
Oxygen is often required to resolve the shortness of breath. Plus, oxygen to the lungs also helps relax the blood vessels and eases right heart failure. Oxygen is given at the rate of not more than 2 liters per minute. Excess oxygen can be harmful to patients because hypoxia is the main stimulus to respiration. If such hypoxia is suddenly corrected by overflow of oxygen, such stimulus to the respiratory center is suddenly withdrawn and respiratory arrest may occur. Therefore, use of domiciliary oxygen should always be under supervision of a physician. Too much oxygen contrary to the expectations can be catastrophic.
When wheezing is present, majority of the patients require agents which expand the bronchi. These drugs can be short or long acting. These agents are often used through sprays and nebulisation’s. A variety of drugs have been developed to relax the blood vessels in the lung. There are a number of new drugs which help in patients whose pulmonary artery pressures are very high. These agents are only prescribed by specialists and include agents like bosentan, ambrisentan and sildenafil etc. When medical therapy fails, one may require a transplant. However, since the lungs and heart both are damaged, both the organs need to be transplanted. This therapy however is very rarely used even in the developed countries of North America and Europe because of its complexity and non-availability of donor organs.
While not all lung diseases can be prevented one can certainly reduce the risk of lung disease. This means avoiding or discontinuing smoking. Patients with end stage lung diseases like chronic obstructive lung disease always end up with right heart failure. When working in environments where there are chemicals, wear masks to prevent inhalation of dust particles. Needless to say, an early diagnosis always helps to prevent serious complications.
Disclaimer: The views and opinions expressed in this article are the personal opinions of the author.
The facts, analysis, assumptions and perspective appearing in the article do not reflect the views of GK