Chronic Pulmonary Thromboembolism and Pulmonary Thromboendarterectomy



Chronic Pulmonary Thromboembolism and Pulmonary Thromboendarterectomy


Michael M. Madani

Stuart W. Jamieson



Pulmonary thromboendarterectomy (PTE) for the treatment of chronic thromboembolic pulmonary hypertension (CTEPH) is an uncommon surgical procedure; however, it is the only curative option that provides immediate and permanent cure for this devastating disease. The condition is remarkably underdiagnosed, and as a result the procedure is uncommonly applied. Patients with chronic pulmonary hypertension secondary to thromboembolic disease may present with a variety of debilitating cardiopulmonary symptoms. However, once it is diagnosed, there is no curative role for medical management, and surgical removal of the thromboembolic material is the only therapeutic option.

The exact incidence of pulmonary embolism (PE) is unknown, but there are some valid estimates. Acute PE is the third most common cause of death (after heart disease and cancer). Approximately, 75% of autopsy-proven PEs are not detected clinically. It is estimated that PE results in approximately 700,000 symptomatic episodes in the United States yearly. The disease is particularly common in hospitalized elderly patients. Of the hospitalized patients who develop PE, 12% to 21% will die in the hospital, and another 24% to 39% die within 12 months. Thus, approximately 36% to 60% of the patients who survive the initial episode live beyond 12 months, and they may present later in life with a wide variety of symptoms.

The mainstay of treatment of patients with deep vein thrombosis (DVT) and acute PE is medical management. In general, cardiac surgeons rarely intervene in hospitalized patients who suffer a massive embolus that causes life-threatening acute right heart failure and severe hemodynamic compromise. In contrast, the only treatment for patients with chronic pulmonary thromboembolic disease is the surgical removal of the disease by means of PTE. Medical management in these patients is only palliative, and surgery by means of transplantation is an inappropriate use of resources with less than satisfactory results.

The prognosis for patients with pulmonary hypertension is poor, and it is worse for those who do not have intracardiac shunts, since the shunt will reduce right-sided pressures. Thus, patients with primary pulmonary hypertension and those with pulmonary hypertension secondary to pulmonary emboli fall into a higher risk category than those with Eisenmenger syndrome and have a higher mortality rate. In fact, once the mean pulmonary pressure in patients with thromboembolic disease reaches ≥50 mmHg, the 3-year mortality approaches 90%.

Surgical preferences are dependent on both the principal disease process and the reversibility of the pulmonary hypertension. With the exception of thromboembolic pulmonary hypertension, lung transplantation is the only effective therapy for patients with end-stage pulmonary hypertension. Although it has been performed less frequently in the last few years, pulmonary transplantation is still used in some centers as the treatment of choice for patients with thromboembolic disease. However, a true assessment of the effectiveness of any therapy should take into account the total mortality after the patient has been accepted and put on the waiting list. Thus, the mortality for transplantation (and especially double-lung or heart-lung transplantation) as a therapeutic strategy is much higher than is generally appreciated because of the significant loss of patients awaiting donors. Bearing in mind, in addition, the long-term use of immunosuppressants with their associated side effects, the higher operative morbidity and mortality, the inferior prognosis even after successful transplantation, and the long waiting period, one can see that transplantation is clearly an inferior alternative to PTE and should be considered an inappropriate and outdated form of therapy.


INCIDENCE

Determining an accurate incidence of CTEPH is almost impracticable. Most patients with this condition do not have a clear history of DVT or PE. Furthermore, the majority (about 75%) of autopsy-proven PEs are not clinically diagnosed. This makes the exact incidence of this disease even more difficult to determine than that of acute PE. A conservative estimate only considers patients who do have an acute PE and survive the episode. There are approximately 600,000 such patients every year in the United States. The incidence of chronic thrombotic occlusion in the population depends on what proportion of patients fails to resolve acute embolic material. Recent studies have shown that of these patients, up to 3.1% will have symptomatic CTEPH at 1 year and 3.8% will have it at 2 years. If these figures are correct, and if one counts only patients with symptomatic acute pulmonary emboli, approximately 18,000 to 22,000 individuals would progress to CTEPH in the United States each year. However, because many (if not most) patients diagnosed with chronic thromboembolic disease have no antecedent history of acute embolism, the true incidence of this disorder must be much higher.

Regardless of the exact incidence or the circumstances, it is clear that both acute embolism and its chronic relation, fixed chronic thromboembolic occlusive disease, are much more common than generally appreciated and are seriously underdiagnosed. Calculations extrapolated from mortality rates and the random incidence of major thrombotic occlusion found at autopsy support a postulate that more than 100,000 people in the United States currently have pulmonary hypertension that could be relieved by operation.





CLINICAL PRESENTATION

There are no specific signs or symptoms associated with pulmonary hypertension as a result of chronic pulmonary thromboembolism, which explains the degree of underdiagnosis with this condition. The most common symptom associated with thromboembolic pulmonary hypertension, as with all other causes of pulmonary hypertension, is exertional dyspnea. Generally, this dyspnea is out of proportion to any abnormalities found on clinical examination. Like complaints of easy fatigability, dyspnea that initially occurs only with exertion is often attributed to anxiety or being “out of shape.” In patients with more advanced disease and higher pulmonary artery pressures, syncope or presyncope (lightheadedness during exertion) is another common symptom.

Nonspecific chest pains occur in approximately 50% of patients with more severe pulmonary hypertension. Hemoptysis can occur in all forms of pulmonary hypertension and probably results from abnormally dilated vessels distended by increased intravascular pressures. Peripheral edema, early satiety, and epigastric or right upper quadrant fullness or discomfort may develop as the right heart fails (cor pulmonale). Some patients with chronic pulmonary thromboembolic disease present after an additional small acute pulmonary embolus that may produce acute symptoms of right heart failure. A careful history will bring out symptoms of dyspnea on minimal exertion, easy fatigability, diminishing activities, and episodes of angina-like pain or lightheadedness. Further examination reveals the signs of pulmonary hypertension.

The physical signs of pulmonary hypertension are the same no matter what the underlying pathophysiology. Initially, the jugular venous pulse is characterized by a large A wave. As the right heart fails, the V wave becomes predominant. The right ventricle is usually palpable near the lower left sternal border, and pulmonary valve closure may be audible in the second intercostal space. Occasional patients with advanced disease are hypoxic and slightly cyanotic. Clubbing is an uncommon finding.

As the right heart fails, a right atrial gallop is usually present, and tricuspid insufficiency develops. Because of the large pressure gradient across the tricuspid valve in pulmonary hypertension, the murmur is high pitched and may not exhibit respiratory variation. These findings are quite different from those usually observed in tricuspid valvular disease. A murmur of pulmonic regurgitation may also be detected.





Jun 15, 2016 | Posted by in CARDIAC SURGERY | Comments Off on Chronic Pulmonary Thromboembolism and Pulmonary Thromboendarterectomy

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