Introduction
Chronic thromboembolic pulmonary hypertension is the most common form of pulmonary hypertension, which describes an increased pressure in the arteries of the lungs. Chronic thromboembolic pulmonary hypertension is seen in one to four percent of patients with acute pulmonary embolism (formation of blood clots in the arteries supplying the lungs). Pulmonary endarterectomy is a surgical procedure that is recommended for patients with chronic thromboembolic pulmonary hypertension and other conditions affecting the pulmonary artery.
What Is Chronic Thromboembolic Pulmonary Hypertension?
Chronic thromboembolic pulmonary hypertension (CTEPH) refers to a prevalent type of pulmonary hypertension. It develops when the blood pressure in the blood vessels of the lungs is abnormally high, which occurs as a complication of previous blood clots (pulmonary embolism). It is responsible for causing chronic pulmonary hypertension, which results in right heart failure and death. CTEPH causes a decrease in blood oxygen levels, which places additional strain on the heart, due to which the heart has to pump harder to transport blood to the lungs. Pulmonary endarterectomy and pulmonary balloon angioplasty are the treatment choices for CTEPH.
What Is Pulmonary Endarterectomy?
Pulmonary endarterectomy is a surgical procedure to remove blood clots in the pulmonary arteries. It is a complex surgical procedure that eliminates long-term blood clots in the lung's arteries that cannot be treated with medication. Pulmonary endarterectomy is also referred to as pulmonary thromboendarterectomy. Pulmonary endarterectomy remains the gold-standard treatment for patients with surgically accessible arterial obstructions in the pulmonary arteries. Pulmonary endarterectomy reduces pulmonary vascular resistance and helps alleviate right ventricular dysfunction. Pulmonary endarterectomy is the only procedure that can cure chronic thromboembolic pulmonary hypertension. If left untreated, chronic thromboembolic pulmonary hypertension can result in lung damage, heart failure, and even death.
Who Are Eligible for Pulmonary Endarterectomy?
Pulmonary endarterectomy is performed to treat chronic thromboembolic pulmonary hypertension. It is performed to remove the clots in the pulmonary arteries in those patients who do not respond to medications. If the clots do not respond to medications, it can result in scar tissue formation, which increases the blood pressure in the lungs and causes breathing difficulties.
The selection criteria for pulmonary endarterectomy depends on the following factors:
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The severity of chronic thromboembolic pulmonary hypertension and its symptoms.
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The location, extent, and degree of block in the pulmonary artery.
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The age, health, and heart and lung function of the patient.
American College of Chest Physicians recommends that pulmonary endarterectomy should be performed if the following criteria are met:
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New York heart association (NYHA) classification with symptoms of functional class III or IV.
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A pulmonary vascular resistance that is greater than 300 dyn.s.cm⁻⁵ preoperatively.
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Surgically accessible embolus in the lobar or segmental pulmonary arteries.
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No severe comorbidities.
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The absence of any underlying chronic lung disease, either restrictive or obstructive type.
Pulmonary endarterectomy is considered if the clots can be safely removed. However, about 40 percent of patients are not eligible for pulmonary endarterectomy due to the complexity of the technique. It is contraindicated in patients with hemodynamic or ventilation impairments. Oral medications and interventional procedures like balloon pulmonary angioplasty are considered for patients who are not eligible for pulmonary endarterectomy.
How Is Pulmonary Endarterectomy Performed?
Pulmonary endarterectomy is a bilateral technique because chronic thromboembolic pulmonary hypertension occurs as a bilateral disease in most cases. Pulmonary endarterectomy involves median sternotomy, cardiopulmonary bypass, deep hypothermia, and cardioplegia. Cardiopulmonary bypass involves the use of a machine that temporarily performs the function of the heart and lungs during the pulmonary endarterectomy. This machine bypasses the heart and lungs while circulating and oxygenating blood for the body. Deep hypothermia involves periods of cooling the body to stop the brain function. Deep hypothermia stops all blood circulation, resulting in circulatory arrest. This process provides better visibility of the surgical site. Also, the cooling process protects the brain from neurological damage during the surgery. The removal of the embolus is performed under deep hypothermia and periods of circulatory arrest. Cardioplegia refers to the cessation of a heartbeat using a crystalline fluid. It is initiated during the approach to the pulmonary arteries as the movement of the heart causes difficulties while working on the closely attached pulmonary arteries.
Hypothermia is essential as the embolus is high and may result in disruption. After cardioplegia, the pulmonary artery is dissected to visualize the clot. Hypothermia allows the visualization of the clot in a bloodless field. Once visualized, the clot is removed. The circulatory arrest is limited to a time interval of 20 minutes to protect brain function. After each interval of arrest, circulation is continued for 10 minutes or until the oxygen saturation is 90 percent. A surgeon removes the clot in the pulmonary artery within the periods of circulatory arrest. Once the procedure ends, the bypass machine is removed, the temperature is returned to normal, and the patient is put on a ventilator. During rewarming, the patient's body is rewarmed.
What Are the Advantages of Pulmonary Endarterectomy?
Pulmonary endarterectomy cures chronic thromboembolic pulmonary hypertension and improves breathing and the lung function of the patient. In the majority of patients, it eliminates the need for oxygen therapy and reverses the damage to the right heart. Pulmonary endarterectomy also improves the long-term survival of the patient.
What Are the Complications of Pulmonary Endarterectomy?
The risk of not surviving pulmonary endarterectomy is as low as one percent in most patients. Some patients may have some degree of pulmonary hypertension even after the surgery and may require medications. Some patients may develop pericardial effusion (fluid buildup around the heart) after surgery. Shortness of breath, fainting, or chest pain may be seen in some patients. A deep hypothermic circulatory arrest can cause various complications, such as coagulative disorders, lung-reperfusion injuries, renal failure, postoperative delirium, and neurological deficits. A new method of clamping was followed to avoid the complications of pulmonary endarterectomy.
Conclusion
Chronic thromboembolic pulmonary hypertension is the most common type of pulmonary hypertension, which may result in heart failure and death if left untreated. Pulmonary endarterectomy is a surgical technique that treats chronic thromboembolic pulmonary hypertension and other disorders of the pulmonary artery such as tumors and endarteritis. Pulmonary endarterectomy shows promising results by improving heart and lung function and providing long-term survival to patients with chronic thromboembolic pulmonary hypertension. Pulmonary endarterectomy cures chronic thromboembolic pulmonary hypertension and improves the overall survival of the patients eligible for undergoing this procedure.
