Dr Kumud Kumar Dhital is a Program & Surgical Director, Institute of Heart & Lung Transplantation Yashoda Group of Hospitals, Hyderabad
There are several life saving surgeries that have increased, if not more, the life span of patients suffering from dangerous diseases. A case in point is Pulmonary Endarterectomy, a specialist surgical procedure for Pulmonary Hypertension (PH) resulting from a condition called Chronic Thromboembolic Pulmonary Hypertension (CTEPH). In the context of CTEPH, untreated pulmonary hypertension of >40mmHg has a poor prognosis with a five-year survival of 30% and if the pulmonary pressure is >50 mmHg, then the five-year survival is only 10%.
The following describes what CTEPH is, how it presents, how it is diagnosed and what treatment options are available.
Chronic Thromboembolic Pulmonary Hypertension (CTEPH) is a relatively rare, but potentially lethal and significantly underdiagnosed condition. It is one of many conditions that leads to PH and usually caused by blood clots or thrombi which narrow or block one or more arteries in the lung. An estimated 800 individuals per million population will have a PE of which 4% will develop CTEPH and up to a quarter of them will benefit from a surgical procedure called Pulmonary Endarterectomy (PEA). If these blood clots, which stick to the internal walls of the pulmonary arteries, do not disappear on their own or following treatment with blood thinning medication, then the right ventricle struggles to pump blood into the lung circulation so that less oxygen is available for normal activity. This triggers the onset of symptoms. In time, these unresolved blood clots become organised into a chronic scar tissue and continue to restrict the normal flow of blood within the pulmonary circulation.
The diagnosis of CTEPH is confirmed once there is evidence of chronic clots within the pulmonary arteries despite three months of treatment with blood-thinning anticoagulant medication and the mean pulmonary artery pressure is equal to or more than 25 mmHg on a right heart catheter study with normal left heart function.
PEA, historically referred to as Pulmonary Thromboendarterectmy, is a complex surgical procedure that is a curative treatment for selected patients diagnosed with advanced CTEPH. Surgery involves general anaesthesia, a midline opening of the chest (sternotomy) as per most heart operations and the use of the heart-lung machine. As it is impossible to see through blood, the procedure requires cooling the body to 20 degree Celsius (deep hypothermia) and periods of circulatory arrest so that no blood is flowing. This technique of deep hypothermic circulatory arrest is a very safe and well established practice in cardiothoracic surgery. It permits excellent visualisation of the disease so that all of the obstructive material can be removed to re-establish adequate blood flow in the pulmonary arteries. Sometimes, a portion of the disease that is very distal in the pulmonary arteries may not be amenable to PEA surgery. This results in some patients being left with a degree of residual disease and associated PH which may necessitate a combination of medical and BPA treatment.
The outcomes from PEA surgery depend on the degree of PH, the extent and distribution of the disease, as well as patient age and other concomitant medical conditions. In experienced centres with a focused CTEPH team, the immediate risk of surgery is under 5%. For those patients whose pulmonary pressures return to normal immediately after surgery, the outcome is excellent with a survival prognosis similar to peers of the same age in the community. When all high and low risk patients are grouped together, the expected survival following hospital discharge is around 90% at five years, 80% at 10 years and 60% at 15 years.