Histological Changes of Pulmonary Arteries Treated by Balloon Pulmonary Angioplasty in a Patient With Chronic Thromboembolic Pulmonary Hypertension

Abstract

A 41-year-old man was referred to our hospital for the treatment of chronic thromboembolic pulmonary hypertension (CTEPH). On admission, he was in World Health Organization functional class III. Right heart catheterization demonstrated that pulmonary arterial pressure (systolic/diastolic/mean) was 140/42/71 mm Hg, cardiac index was 1.6 L/min/m2 and pulmonary vascular resistance was 1663 dyn ·s·cm -5 . The patient had severe pulmonary hypertension and was considered inoperable because of peripheral organized thrombi and coexisting seminoma; therefore, balloon pulmonary angioplasty (BPA) was performed. After BPA, pulmonary angiography showed improvement of pulmonary arterial flow ( Figure 1A). Pulmonary arterial pressure was 108/42/67 mm Hg and cardiac index was 2.5 L/ min/m 2 when he returned to the cardiac care unit after BPA. His condition temporarily improved; however, 2 hours later, it deteriorated because of reperfusion pulmonary injury and gastrointestinal bleeding. He required mechanical ventilation and percutaneous cardiopulmonary support. To improve hemodynamics, another session of BPA was tried 9 days later (Figures 2A and 3A) and pulmonary arterial pressure seemed to improve to 83/48/58 mm Hg. However, he died from right heart failure on day 26 after BPA despite intensive care.Histological analysis of the autopsy specimens showed recanalized thrombi in the bilateral elastic pulmonary arteries ( Figure 4). Diffuse pulmonary arterial medial and intimal thickening were also observed in muscular pulmonary arteries. These findings are consistent with CTEPH and the diagnosis was confirmed. The arterial media was dissected near the lamina elastica interna by BPA ( Figures 1B, 2B, and 3B). The organized thrombi were forced to one side and the dissection formed pseudovascular spaces that configured new lumina, which were larger than the original channels. Newly formed intima was observed on the inner surface of these pseudovascular spaces ( Figures 1B-c, 2B-b, and 3B-b, black arrowheads).According to the guidelines for the diagnosis and treatment of pulmonary hypertension, pulmonary endarterectomy is a standard therapy for patients with CTEPH with proximal thrombi.1 However, not all patients can undergo this curative surgery because of the presence of thrombi in distal pulmonary arteries, difficulty of the operation, or comorbidities. We have reported that BPA could improve hemodynamics in inoperable patients with CTEPH.2 However, it is unknown how pulmonary arteries are changed by BPA and the mechanism by which hemodynamic improvement is achieved, although thrombi are not removed from the affected arteries. We have recently reported a case in which we were able to examine a pulmonary artery in a single lobe after BPA.3 A pathological examination of the dilated lesion showed that the vascular lumen was dilated by a small incision and compression of the thrombi without dissection. In contrast, the histology of the present case demonstrated that the lumina were dilated by the dissection at a plane in the media (...

Novel Angiographic Classification of Each Vascular Lesion in Chronic Thromboembolic Pulmonary Hypertension Based on Selective Angiogram and Results of Balloon Pulmonary Angioplasty

“…It is essential that physicians performing angioplasty and other 14 We need to understand the outcomes of severe complications (such as dissection or perforation of pulmonary arteries) and how to manage these complications when performing BPA for CTEPH. 21,22 In conclusion, we reclassified thromboembolic lesions of CTEPH into 5 types by modifying the widely used previous angiographic classification and demonstrated that the outcome and complication rate of BPA are closely related to the location and morphology of the thromboembolic lesion. This novel classification might be helpful in developing strategies to perform BPA in patients with CTEPH who are unsuitable for PEA.…”

Treatment of Chronic Thromboembolic Pulmonary Hypertension: The Role of Medical Therapy and Balloon Pulmonary Angioplasty

“…In the second, the media of the PA was dissected by angioplasty and the organized thrombi were forced to one side, leaving a larger pseudo-lumen with formation of a new intimal layer. 40 …”

After the Dawn ― Balloon Pulmonary Angioplasty for Patients With Chronic Thromboembolic Pulmonary Hypertension ―

“…Vessel diameter spontaneously expanded over time and ultimately the pressure gradient across the lesion was eliminated. Given our previous observation of vessel wall dissection caused by BPA, 31 we speculate that pressure overload in the pulmonary artery with partial detachment of an organized thrombus may cause dilatation of the artery distal to the occlusion. For this reason, we recently began to use small balloons at the initial dilatation, increasing the diameter of dilatation at subsequent procedures, a protocol that increases safety by avoiding vascular complications.…”

“…In pathologically examined lesions after BPA, we found a small incision through the organized thrombus in 1 case, 30 and dissection of the tunica media with partial detachment of the organized thrombus from the vascular wall in other cases (Figure 3). 31 Thus, the thrombi were not extracted from inside the blood vessel as in PEA, but were forced to one side to enlarge the lumen.…”

“…We chronologically measured perfusion pressure in the 31 ) Structure of a pulmonary artery with organized thrombus (green) and recanalized channels (red) (Left) is thought to be changed by BPA (Right). The lumen is opened wide by dissection in the medial wall and the organized thrombus is compressed to one side.…”