Various Cardiac Signs in Respiratory Diseases

The heart and lungs are the two most important organs of the human body. The heart acts as a pump and circulates blood in the body. Lungs receive deoxygenated blood from the heart and supply oxygenated blood to the heart. These two organs act in close collaboration and maintain circulatory equilibrium in the body. As a result, any pathological conditions affecting the heart or lungs affect the functioning of the other organ also.

What Is the Relationship between the Heart and the Lungs?

The heart is a triangular-shaped muscular organ. It consists of four chambers. Blood from different parts of the body enters the heart via the right atrium. From the right atrium, blood goes to the right ventricle. The right ventricle pumps blood to the lungs. The blood reaches the lungs through pulmonary blood vessels. After reaching the lungs the deoxygenated blood is transformed into oxygenated blood through gaseous transfusion. Oxygenated blood then comes to the left atrium. From the left atrium, the blood goes to the left ventricle. The left ventricle pumps the blood to circulate into the whole body.

Anatomically the shape and the structure of the right ventricle are similar to the left ventricle. But the right ventricle is one-sixth the mass of the left ventricle. The passage of blood from the heart to the lungs and then back to the heart takes place via pulmonary circulation. Pulmonary circulation comprises arteries, veins, and lymphatic systems. The arterial circuit for pulmonary circulation arises from the right ventricle. The pulmonary artery is divided into numerous small branches. Numerous arteries, arterioles, and capillaries arise from the pulmonary artery. The thickness of the pulmonary artery is approximately one-third of the other arteries but the diameter is more. This creates less resistance (one-tenth of the systemic circulation) to the circulatory blood.

The pulmonary veins are formed by the anastomosis of the venules. These venules receive blood from capillaries around the alveoli. The pulmonary veins are also thinner with sustainable properties. These facilitate carrying more blood to the left atrium and also reduce the resistance of blood circulation. The lymphatic drainage of the pulmonary circulation help to remove accumulated fluid around pulmonary circulation.

What Is the Effect of Chronic Lungh Disorder?

Chronic lung diseases are responsible for several changes in the systemic circulation. Several changes in the physiologic conditions lead to this. One of the main effects of chronic lung disease is a lack of oxygen supply. This leads to the activation of chemoreceptors which causes dilation of the peripheral blood vessels. But pulmonary blood vessels are constricted. This pulmonary vasoconstriction helps to maintain ventilation and perfusion in the alveoli. This causes an increase in pulmonary artery pressure. This increase in pressure is ultimately responsible for pulmonary hypertension and an increase in vascular resistance. Asa result, a rise in cardiac output is observed.

Another factor, that is associated with such changes is hypercarbia. In this condition, the concentration of carbon dioxide in the blood is also increased. This causes hyperventilation and constriction of pulmonary blood vessels. Though, peripheral blood vessels are dilated.

In long-standing cases this can lead to the following changes:

1. Change in the morphology of the pulmonary vasculature. Muscularization and proliferation of the vascular media and intima (layers of the blood vessels) lead to the alteration in the tone of the pulmonary blood vessels.

2. Long-standing infection and inflammation lead to the loss of pulmonary vascular surface area.

3. Chronic lung diseases are associated with changes in the viscosity of the blood.

All these factors are responsible for increased vascular resistance in the pulmonary circulation. Chronic lung diseases associated with such changes are:

1. Chronic obstructive pulmonary disorder (COPD).

2. Lung fibrosis.

3. Interstitial lung disorders.

4. Cystic fibrosis.

5. Pulmonary embolism.

What Are the Effects on the Heart?

Changes in the pulmonary circulation, increased resistance of the pulmonary circulation, and pulmonary hypertension lead to increased preload and afterload on the ventricles. Cardiac output is also increased. Hypercapnia (elevation in the carbon dioxide tension in the blood vessels) is responsible for alterations in renal blood flow. As a result, water and salt absorption in the kidney is hampered. Vasodilation of the peripheral blood vessels is responsible for circulatory stasis. This is associated with the accumulation of fluid in the periphery.

All these factors lead to increased stroke volume, increased heart rate, and cardiac output. Swelling of the leg and accumulation of fluid in the peripheral blood vessels are also seen.

Increased pulmonary pressure and pulmonary hypertension are associated with increased afterload. As a result, increased force is necessary for the right ventricle to pump blood into the lungs. This causes hypertrophy (increased in size) of the right ventricle. Left-sided heart disorders are uncommon but can be observed in some conditions. Increased age, smoking, and COPD are potential risk factors in the development of left-sided lung disorders.

What Are the Symptoms?

The symptoms of right ventricular failure or cor pulmonale or right-sided heart failure are:

1. Discomfort in the chest, usually in the front left side of the chest.

2. Breathing discomfort after heavy work or exercise.

3. Chest pain.

4. Swelling in the body specifically in the lower extremities like the ankle.

5. Bluish discoloration of the fingers and lips.

6. Presence of wheezing or cracking sound in the chest due to chest discomfort.

On the clinical examination following details can be found:

1. The chest radiograph will show enlargement of the right ventricle and pulmonary artery.

2. Electrocardiogram will show hypertrophy of the right ventricle.

3. Doppler echocardiography can be used to detect pulmonary hypertension.

4. Magnetic resonance imaging (MRI) can be used to determine the dimensions and enlargement of the right ventricle.

5. Pulmonary function tests can be used to diagnose the presence of pulmonary disorders.

What Are the Treatment Options?

Treatment of the respiratory disorder is the primary mood of treatment in such cases. The oxygenation of the patient can be improved by oxygen therapy. Diuretics can be used to remove accumulated fluid from the body. Anticoagulants can be prescribed to reduce the chance of blood clot formation. ACE inhibitors and angiotensin II receptor blockers can be used to improve the functionality of the heart.

Conclusion:

The heart and the lungs are the two most vital organs in the human body. Pulmonary circulation plays a vital role in the gaseous exchange process. Chronic respiratory disorders are responsible for pulmonary hypertension and increased resistance to pulmonary circulation. This is responsible for right-sided heart failure.