By Robert A. Sandhaus, MD, Ph.D., FCCP – Medical Director, AlphaNet
Note: This is not an exhaustive discussion of pulmonary hypertension in general but limited to the major issues related to this condition faced by the Alpha-1 community.
Nearly everyone has heard the fancy medical word for high blood pressure: hypertension. This very common condition is easy to diagnose by wrapping a blood pressure cuff around someone’s arm and taking a reading. But many Alphas with lung disease suffer from a much more difficult-to-diagnose type of hypertension that can have serious health consequences if not identified: pulmonary hypertension.
Pulmonary hypertension is an elevation of the pressures in the blood vessels feeding the lungs. This often occurs without any elevation in the blood pressure in the rest of the body. When significant pulmonary hypertension is present it can lead to a variety of symptoms including increased shortness of breath often with exertion, chest pain, liver swelling, fluid accumulation in the legs or abdomen, and a form of heart failure known as cor pulmonale (see below). A major problem with diagnosis is that when pulmonary hypertension is still in its early stages and the pressures in the blood vessels are only mildly elevated, there are often no symptoms at all. The earlier that pulmonary hypertension is identified, the easier it is to treat.
So what is the relationship between pulmonary hypertension and Alpha-1?
Alpha-1 itself does not directly lead to pulmonary hypertension but individuals with lung disease due to Alpha-1 are at risk of a form of this condition known as secondary pulmonary hypertension. Secondary pulmonary hypertension is due to prolonged low oxygen levels in the lung. The lung has a built-in mechanism that is designed to close down the blood supply to parts of the lung that are not receiving enough oxygen. Presumably, this is a defense mechanism that would shunt blood away from a section of the lungs that might have a blocked airway (caused by aspiration of a foreign body like a peanut, for example) or a damaged area of the lung (such as in severe pneumonia localized to one or two lobes of the lung). Closing down these blood vessels will effectively shunt the blood supply of the lung away from these ineffective areas to more normal areas of the lung, allowing the blood to continue to pick up normal amounts of oxygen.
But what happens if the damage to the lungs and low oxygen levels are spread throughout the lung as in someone with the generalized emphysema of Alpha-1?
In that case, all the blood vessels in the lung start to spasm and close down. This results in elevation of the pressures of the major blood vessels that bring blood into the lungs from the right side of the heart, leading to pulmonary hypertension. It is called secondary pulmonary hypertension in this setting because the elevated pressures are the result of (or secondary to) the low oxygen levels in the lungs.
When pulmonary hypertension becomes severe, it strains the function of the right side of the heart. The right heart chambers enlarge or dilate, and if this continues long enough, the pumping action of that side of the heart becomes much less effective. This is called ‘right heart failure.’ When right heart failure is due to pulmonary hypertension from lung disease this is known as cor pulmonale (pronounced core’-pul-mon-a’-ly). When the right side of the heart fails, fluid “backs up” into the veins that feed the right heart. These veins normally drain the extremities and the abdomen so the result can be fluid (or edema) swelling the liver, the ankles and legs, and very full jugular veins in the neck.
The good news about this type of secondary pulmonary hypertension is that maintaining adequate oxygen levels with supplemental oxygen can prevent it from ever occurring. Individuals with early signs of pulmonary hypertension can reverse these changes by starting supplemental oxygen in a timely fashion. Even those with advanced cor pulmonale will benefit from returning their oxygen levels back to normal by using supplemental oxygen 24 hours a day.
So how do you know if you have pulmonary hypertension?
There is no simple office test that can make the diagnosis. If someone with lung disease and low oxygen begins to show signs of right heart failure, then pulmonary hypertension is likely. But it is important to make this diagnosis before such heart effects are seen.
There are some changes that can be seen in a simple EKG when pulmonary hypertension strains the heart. The most common non-invasive method to evaluate the blood pressure in the pulmonary arteries is a cardiac echo or ultrasound, also called an echocardiogram. The echocardiogram can look for enlargement of the pulmonary artery and can also make indirect measurements of pulmonary artery pressure. The problem with the echocardiogram is that air in the lungs can block the sound waves that produce the image of an echocardiogram. People with lung disease due to Alpha-1 usually have hyperexpanded lungs and air trapping that make imaging the pulmonary arteries difficult.
Another indirect method of looking for pulmonary hypertension is a chest x-ray or CT scan of the chest. These types of x-ray studies produce images of the pulmonary arteries that can be evaluated for enlargement of these vessels which can be an early sign of increased blood pressure.
The “gold standard” for evaluating pulmonary artery blood pressure is heart catheterization. This technique involves threading a catheter into one of the main veins draining the leg, arm or neck, and advancing it into the heart to measure pressure directly. This is more invasive and is often not needed in the setting of secondary pulmonary hypertension, but may be required if other techniques don’t give a reliable answer.
If there is a bottom line to this story, it is a reinforcement that when supplemental oxygen is indicated for patients with lung disease due to Alpha-1 because of low oxygen levels at rest, with exercise, or during sleep, its use will not only improve your ability to function today but it will also prevent the more serious complication of secondary pulmonary hypertension in the future.
There is also a form of pulmonary hypertension known as idiopathic pulmonary arterial hypertension. This is often a serious medical condition in which there are abnormalities of the small blood vessels within the lungs leading to elevated pressures in the pulmonary arteries without any apparent lung disease. This can be life-threatening but, fortunately, there are a variety of new therapies that are available for this population. There is no evidence that people with Alpha-1 are at higher risk of developing this form of pulmonary hypertension.
Lastly, there is a form of pulmonary hypertension that results from liver disease. The bottom line is that swelling in the abdomen or feet is not just part of getting older and should be evaluated.