Abstract
Chronic thromboembolic pulmonary hypertension (CTEPH) is one of the major causes of pulmonary arterial (PA) hypertension presenting with severe disability and often fatal outcome. Although this condition is often misdiagnosed as a disease showing similar pathophysiological characteristics such as primary pulmonary hypertension (PPH), it is potentially curable by thromboendarterectomy (PTE) if bilateral thrombotic legions in the proximal (main or lobar) PA are accurately assessed and definable for the surgical accessibility. Recent studies have shown that intravascular imaging provides direct evidence of lesions in PA as well as coronary and peripheral arteries. The purpose of this study is to clarify whether intravascular imaging is valuable in making the differential diagnosis and determining the surgical indication in patients with CTEPH. An angioscopy (XPF-30AL, Olympus, Tokyo, Japan) with an inflatable balloon on the distal tip and a mechanically rotated intravascular ultrasound imaging system (IVUS; SSD550, Aloka, Tokyo, Japan) were utilized. Direct visualization with these devices was performed in consecutive 25 patients initially diagnosed as CTEPH with angiographically equivocal surgical indication. Angioscopy was particularly useful in determining the location and extent of organized thrombi and thickened intima, recognized by the deformity of the intima and lumen in CTEPH. On the other hand, IVUS could quantify the magnitude of the thickness of intima and luminal thrombi, and therefore made iteasy to determine the surgical accessibility and procedure. A three layered structure with an intermediate echo-lucent zone and at hickening of the intima-media complex more than 1.0mm in the proximal PA determined by IVUS were reliable predictors for complete PTE in CTEPH, because ten patients whose images met to the criteria described above were successfully operated on. These images were also helpful in making final diagnosis in 7 of 25 patients Five with PPH and each one with neoplasm and vasculitis in PA, respectively.
In conclusion, intravascular imaging in PA might contribute significantly to the final diagnosis and surgical decision making in patients with CTEPH.
