Pulmonary hypertension after pulmonary emboli: an underrecognized condition

• Published in: Canadian Medical Association journal (CMAJ) 2006-06, Vol.174 (12), p.1706-1706
• Main Authors: de Perrot, Marc, Granton, John, Fadel, Elie
• Format: Article
• Language: English
• Subjects: Analysis; Cardiovascular disease; Diagnosis, Differential; Endarterectomy; Health risk assessment; Humans; Hypertension; Hypertension, Pulmonary - diagnosis; Hypertension, Pulmonary - etiology; Medical diagnosis; Prognosis; Pulmonary arteries; Pulmonary Artery - surgery; Pulmonary Embolism - complications; Pulmonary Embolism - diagnosis; Pulmonary Embolism - surgery; Surgery; Tomography
• ISSN: 0820-3946; 1488-2329
• DOI: 10.1503/cmaj.051646

The definitive diagnosis of pulmonary hypertension is based on measurements made during a right-heart catheterization. If a pulmonary embolus is suspected on the ventilation-perfusion scan and signs of pulmonary hypertension are seen on the echocardiogram, a right-heart catheterization must always be performed to confirm and determine the severity of the pulmonary hypertension. It is occasionally difficult to differentiate between acute pulmonary emboli and CTEPH, and it is only by measuring the right-heart pressures and pulmonary vascular resistance during a cardiac catheterization that the distinction between the 2 clinical entities can be made. Because the normal right ventricle cannot tolerate even moderate elevations in pulmonary vascular resistance, the finding of a mean pulmonary artery pressure greater than 40 mm Hg in the presence of demonstrable pulmonary emboli supports a diagnosis of CTEPH.4 Pulmonary endarterectomy is the treatment of choice for patients with CTEPH. Candidates for surgery are determined on the basis of pulmonary angiography results and helical CT of the chest (Fig. i). Pulmonary angiography confirms the diagnosis of CTEPH and helps in determining whether endarterectomy is feasible by demonstrating the location of the obstruction. Obstructions starting at the level of the Iobar and segmentai branches of the pulmonary artery are usually accessible to pulmonary endarterectomy. Newgeneration helical CT can show partial obstruction of the arterial lumen and abnormal thickening of the arterial wall down to the segmentai branches, and it is therefore a good complement to pulmonary angiography for assessing patients for surgery. However, a normal CT scan result does not exclude the diagnosis of CTEPU, nor does it preclude the possibility of endarterectomy. All patients presenting with pulmonary arterial hypertension and segmentai perfusion defect on the ventilation-perfusion scan must have a pulmonary angiogram to determine the feasibility of endarterectomy. Pulmonary endarterectomy can restore near-normal cardiopulmonary function after surgery. The surgery is performed on cardiopulmonary bypass with a period of circulatory arrest to remove the obstructive material from each lobar and segmentai branches of the pulmonary artery. The intraluminal material is composed of fibrous tissue that is inseparable from the intima, and it is thus inaccessible to thrombectomy or thrombolysis. Hence, a true endarterectomy is required, starting at th