Clinicopathological Aspects of Chronic Pulmonary Thromboembolic Hypertension with Special Reference to Pulmonary Thromboendarterectomy in Japan

Summary

The incidence of chronic pulmonary thromboembolic hypertension (CPTEH) has been gradually increasing in Japan. Pulmonary thromboendartectomy has been recently performed, but the success rate of this operation is not as good as that in the San Diego group. To clarify the factors leading to a satistactory outcome in this operation, we have clinicopathologically compared seven autopsy cases, including three patients with CPTEH who died after operation, to 11 surgically successful patients. We have classified CPTEH to assess operative indication.

Total surgical specimens and whole pulmonary arterial trees dissected out from the proximal lobar artery to subsegmental arteries were submitted for histological examination. Serial cross sections of these specimens were made by traditional processing, cut at 5 μm in thickness, and stained with H & E, Masson trichrome, and elastica von Gieson stains. Deep vein thrombi were also sought whenever CPTEH was identified.

The results and conclusions were as follows. (1) There were minor differences in numbers and diameter, nothing less than 70%, of occluded segmental arteries between surgically successful patients and autopsy cases. The most obvious difference between them was the thickness of intima of the proximal lobar artery. In patients with surgical success, the intima of lobar arteries was thicker than that of autopsy cases. (2) The sufficient intimal thickening for successful surgery was significantly associated with a known hypercoagulable state (CPTEH-paradox?). (3) Intimal thickening of proximal lobar arteries may be required for obtaining good surgical outcome; therefore, it is of great importance to evaluate the degree of intimal thickening of the lobar artery before operation.