Pulmonary microvascular disease in chronic thromboembolic pulmonary hypertension.
ABSTRACT Distal, small-vessel vasculopathy is generally considered a major contributor to the progression of pulmonary hypertension (PH) as chronic thromboembolic pulmonary hypertension (CTEPH) develops over time and is a major determinant of postoperative outcome after pulmonary endarterectomy (PEA). The pathogenesis and natural history of microvascular disease in CTEPH remain uncharacterized. Mechanisms for significant distal disease may involve the following processes: (1) predominant obstructions of "small" subsegmental elastic pulmonary arteries, (2) classical pulmonary arteriopathy of small muscular arteries and arterioles distal to nonobstructed vessels, (3) pulmonary arteriopathy of small muscular arteries and arterioles distal to totally or partially obstructed vessels. Patients in whom obstructed vessels are mainly subsegmental are considered poor surgical candidates. Distal pulmonary vasculopathy in both the occluded and nonoccluded pulmonary vascular bed is characterized by lesions considered typical for idiopathic pulmonary arterial hypertension, including plexiform lesions. The pathogenesis and time course of these vascular lesions remain unclear, but may involve endothelial and/or platelet production and release of mediators and/or altered pulmonary blood flow. The reciprocal contribution of large-vessel (operable) and small-vessel lesions in CTEPH is crucial for the indication and results of PEA. A combination of investigations is used to identify the extent of small-vessel disease, including right-heart catheterization, perfusion lung scan, multidetector spiral computed tomography, pulmonary angiography, and pulmonary arterial occlusion wave-form analysis. Preliminary evidence suggests that medical therapy may provide hemodynamic and clinical benefits for patients in whom PEA cannot be applied, in those who have persistent postoperative PH, or in selected patients with advanced preoperative hemodynamic changes.
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ABSTRACT: In the 2009 European Guidelines on the diagnosis and treatment of pulmonary hypertension (PH), one section covers aspects of pathophysiology, diagnosis and treatment of chronic thromboembolic pulmonary hypertension (CTEPH). The practical implementation of the guidelines for this disease is of crucial importance, because CTEPH is a subset of PH which can potentially be cured by pulmonary endarterectomy (PEA). Nowadays, CTEPH is commonly underdiagnosed and not properly managed. Any patient with unexplained PH should be evaluated for the presence of CTEPH, and a ventilation/perfusion (V/Q) lung scan is recommended as screening method of choice. If the V/Q scan or CT angiography reveals signs of CTEPH, the patient should be referred to a specialized center with expertise in the medical and surgical management of this disease. Every case has to be reviewed by an experienced PEA surgeon for the assessment of operability. In this updated recommendation, important contents of the European guidelines were commented, and more recent information regarding diagnosis and treatment was added.International journal of cardiology 12/2011; 154 Suppl 1:S54-60. DOI:10.1016/S0167-5273(11)70493-4 · 6.18 Impact Factor