Interventional Imaging Roadmap to Successful Balloon Pulmonary Angioplasty for Chronic Thromboembolic Pulmonary Hypertension

Abstract

Balloon pulmonary angioplasty (BPA) is an evolving treatment modality for patients with chronic thromboembolic pulmonary hypertension (CTEPH) who are not candidates for pulmonary endarterectomy. Although several imaging modalities currently exist for evaluating CTEPH, their individual use, specifically in the clinical practice of BPA, has not been well described. In this article, we provide a preprocedural, intraprocedural, and postprocedural interventional imaging roadmap for safe and effective BPA performance in routine clinical practice. Preprocedural assessment includes transthoracic echocardiography for right ventricular assessment, ventilation/perfusion scan to identify pulmonary segments with the highest degree of hypoperfusion, cross-sectional chest imaging excluding alternative causes of mismatched defects and providing anatomic and perfusion imaging concurrently, and nonselective invasive pulmonary angiography for risk stratification of individual lesion subtypes. Intraprocedural assessment includes subselective segmental angiography (SSA) for delineating segmental and subsegmental branch anatomy, lesion identification, and vessel sizing. Intravascular ultrasound and optical coherence tomography serve as adjunctive intraprocedural tools for more accurate vessel sizing and lesion characterization when SSA alone is insufficient. Postprocedural considerations include chest radiography to monitor for immediate postprocedure complications and echocardiography for the interval assessment of the right ventricle on longer-term follow-up.

Graphical abstract

Figure 1

Characteristic appearance of chronic thromboembolic pulmonary hypertension on ventilation/perfusion scan. Ventilation/perfusion scan showing (A) Multiple perfusion defects with normal ventilation. (B) Mismatched defects.

Figure 2

Features of chronic thromboembolic pulmonary hypertension commonly seen on CTPA. Contrast-enhanced axial computed tomographic image (A) shows an eccentric filling defect making obtuse angles with the pulmonary arterial wall (arrow), consistent with chronic thromboembolic disease. Another image more caudally (B) shows a web-like filling defect in a right lower lobe subsegmental artery (arrow). CTPA, computed tomography pulmonary aniography.

Figure 3

Utility of CT in differentiating pulmonary arterial lesions. Ventilation/perfusion scan with multiple moderately sized perfusion mismatch defects. On coronal contrast-enhanced CT, this corresponded to an occlusive unilateral filling defect in the right pulmonary artery. This defect increased in size on a subsequent CT chest and was proven to be a pulmonary artery sarcoma. CT, computed tomography.

Figure 4

A 70-year-old woman with chronic thromboembolic pulmonary hypertension who underwent BPA. Perfusion maps in the axial (gray scale, A) and coronal (color map, B) planes are shown before BPA. Note the narrowing of the right lower lobe posterior segmental branch (solid arrow, A) compared with the normal appearance of the other right lower lobe segmental branches (dashed arrows, A). This corresponds to a perfusion defect (asterisk, A and B). Additional perfusion defects are also seen bilaterally (darker areas of the lung). After BPA, the revascularized vessel (arrow, C) shows improved patency and enhancement with associated improvement in lung parenchymal perfusion. BPA, balloon pulmonary angioplasty.

Central Illustration

Preprocedural, intraprocedural, and postprocedural considerations of patients undergoing BPA. BPA, balloon pulmonary angioplasty; CTPA, computed tomography pulmonary angiogram; DECT, dual-energy computed tomography; IPA, invasive pulmonary angiography; RV, right ventricular; SSA, subselective segmental angiography; TTE, transthoracic echocardiogram; V/Q, ventilation/perfusion.

Figure 5

Anatomical definitions of chronic thromboemoblic disease. IPA demonstrating generally accepted pulmonary arterial anatomical definitions and indications for PEA and BPA. BPA, balloon pulmonary angioplasty; IPA, invasive pulmonary angiography; PEA, pulmonary endarterectomy; PA, pulmonary artery.

Figure 6

Various lesion abnormalities seen on subselective pulmonary angiography in patients with CTEPH. Subselective pulmonary angiogram appearance of band-like stenosis (solid arrow, A), intravascular webbing (asterisk, B), subtotal occlusion (dashed arrow, C), total occlusion (double asterisk, D), tortuous and diseased vessels (E), optical coherence tomography image of intravascular webbing (F), and pressure gradient measurement during BPA (G and H). BPA, balloon pulmonary angioplasty; CTEPH, chronic thromboembolic pulmonary hypertension.