Pulmonary Vascular Disease

 The definition of pulmonary vascular disease is simply: any condition that affects the blood vessels along the route between the heart and lungs.

Blood travels from the heart, to the lungs, and back to the heart. This process continually refills the blood with oxygen, and allows carbon dioxide be exhaled. Here's how the process works:

• Oxygen-poor blood returns from the body's tissues through the veins back to the right side of the heart.
• The right heart pumps oxygen-poor blood through the pulmonary arteries into the lungs. This blood becomes filled with oxygen.
• The oxygen-rich blood returns from the lungs back to the left side of the heart. The left heart pumps the oxygen-rich blood into the body through the aorta and many other arteries.

Any part of the heart-lung blood circuit can become damaged or blocked, leading to pulmonary vascular disease.

Causes of Pulmonary Vascular Disease

The causes of pulmonary vascular disease vary according to which of the lungs' blood vessels are affected. Pulmonary vascular disease is divided into several categories:

Pulmonary Arterial Hypertension: Increased blood pressure in the pulmonary arteries (carrying blood away from the heart to the lungs). Pulmonary arterial hypertension can be caused by lung disease, autoimmune disease, or heart failure. When there is no apparent cause, it's called idiopathic pulmonary arterial hypertension.

Pulmonary Venous Hypertension: Increased blood pressure in the pulmonary veins (carrying blood away from the lungs, to the heart). Pulmonary venous hypertension is most often caused by congestive heart failure. A damaged mitral valve in the heart (mitral stenosis or mitral regurgitation) may contribute to pulmonary venous hypertension.

Pulmonary Embolism: A blood clot breaks off from a deep vein (usually in the leg), travels into the right heart, and is pumped into the lungs. Rarely, the embolism can be a large bubble of air, or ball of fat, rather than a blood clot.

Chronic Thromboembolic Disease: In rare cases, a blood clot to the lungs (pulmonary embolism) is never reabsorbed by the body. Instead, a reaction occurs in which multiple small blood vessels in the lungs also develop blood clots. The process occurs slowly, and gradually affects a large part of the pulmonary arterial system.

Symptoms of Pulmonary Vascular Disease

The symptoms of pulmonary vascular disease vary according to several factors:

• The suddenness of the process affecting the pulmonary blood vessels
• Which pulmonary blood vessels are affected (where the pulmonary vascular disease is)
• How much of the pulmonary vascular system is affected

For example, a sudden, large pulmonary embolism blocking a large pulmonary artery can cause severe shortness of breath and chest pain. But a very small pulmonary embolism (blocking only a small blood vessel) may cause no noticeable symptoms.

Although symptoms of pulmonary vascular disease can vary widely, each of the causes of pulmonary vascular disease has a set of usual symptoms:

Pulmonary arterial hypertension: This most often causes slowly progressive shortness of breath. As the condition worsens, chest pain or fainting (syncope) with exertion can occur.

Pulmonary embolism: A blood clot to the lungs typically occurs suddenly. Shortness of breath, chest pain (often worse with deep breaths), and a rapid heart rate are common symptoms. Pulmonary embolism symptoms range from barely noticeable to severe, based on the size of the blood clot(s).

Pulmonary venous hypertension: This form of pulmonary vascular disease also causes shortness of breath, due to the congestive heart failure that's usually present. Shortness of breath may be worse while lying flat, when blood pressure is uncontrolled, or when extra fluid is present (edema).

Tests for Pulmonary Vascular Disease

Computed tomography (CT scan): A CT scanner takes multiple X-rays, and a computer constructs detailed images of the lungs and chest. CT scanning can usually detect a pulmonary embolism in a pulmonary artery. CT scans can also uncover problems affecting the lungs themselves.

Ventilation/perfusion scan (V/Q scan): This nuclear medicine test takes images of how well the lungs fill with air. Those images are compared to pictures of how well blood flows through the pulmonary blood vessels. Unmatched areas may suggest a pulmonary embolism (blood clot) is present.

Echocardiography (echocardiogram): An ultrasound video of the beating heart. Congestive heart failure, heart valve disease, and other conditions contributing to pulmonary vascular disease can be discovered with an echocardiogram.

Right heart catheterization: A pressure sensor is inserted through a needle into a vein in the neck or groin. A doctor advances the sensor through the veins, into the right heart, then into the pulmonary artery. Right heart catheterization is the best test to diagnose pulmonary arterial hypertension.

Chest X-ray film: A simple chest X-ray can't diagnose pulmonary vascular disease. However, it may identify contributing lung disease, or show enlarged pulmonary arteries that suggest pulmonary arterial hypertension.

Pulmonary angiography (angiogram): Contrast dye is injected into the blood, and X-ray images of the chest show detailed images of the pulmonary arterial system. Angiography is very good at diagnosing pulmonary embolism but is rarely performed anymore because CT scans are easier, less invasive, and have lower risk.