The imaging modalities including ventilation-perfusion scan, computed tomography angiography (CTA), and magnetic resonance angiography (MRA) now provide much of the diagnostic information that can be derived from pulmonary angiography with less risk and at lower cost.¹,²,³,⁴,⁵ At the same time the number and variety of vascular interventional procedures in the pulmonary vasculature have increased moderately. On balance, the total number of pulmonary angiography performed for the diagnosis of pulmonary embolism (PE) has decreased with the introduction of contrast-enhanced CT, whereas the number of cases for intervention has significantly increased. Pulmonary angiography is generally requested only when pulmonary arterial vascular lesions are suspected or necessary information about the pulmonary arterial vasculature cannot be obtained by CTA or MRA. Pulmonary angiography is performed for the diagnosis of PE, to evaluate the etiology of pulmonary hypertension, to assess the extent and anatomy of the chronic PE before surgical intervention, before pulmonary catheter embolectomy and/or catheter-directed thrombolysis for massive or submissive PE, and for the diagnosis and treatment of pulmonary artery aneurysms and pseudoaneurysms, and arteriovenous malformations. This chapter (atlas) reviews the vascular anatomy as well as the techniques of pulmonary angiography and intervention in the diagnosis and treatment of pulmonary arterial vascular disease.

The main pulmonary artery arises from the conus of the right ventricle, commencing at the pulmonic valve. It courses 4 to 5 cm posterosuperiorly before dividing into the right and left pulmonary arteries (FIGURE 12.1). The right pulmonary artery courses horizontally, passing anterior to the right main stem bronchus and posterior to the ascending aorta and superior vena cava (SVC). The right upper lobe branch arises before reaching the right hilum and divides into the 3 segmental upper lobe arteries (apical, anterior, and posterior segmental). After the takeoff of the upper lobe artery, the pulmonary artery becomes pars interlobaris until the origin of the middle lobe artery (medial and lateral segmental). The artery then divides into 4 basal segmental branches (anterior, medial, lateral, and posterior basal) and superior segmental branch (FIGURE 12.2). Left pulmonary artery is a direct posterior continuation of the main pulmonary artery, crossing over the left main stem bronchus and gives rise to 3 segmental branches to the upper lobe and 2 lingular segmental branches (superior and inferior segmental). It then gives rise to 4 lower lobe basal segmental (anterior, medial, lateral, and posterior basal) and superior segmental branch (FIGURE 12.3).

Thorough understanding of the segmental anatomy of the lung is important in the performance and interpretation of ventilation and perfusion scan, CTA, and pulmonary angiography for the diagnosis of PE. When performing pulmonary arteriography, oblique views are recommended for optimal visualization of the pulmonary arterial vasculature.

All prior images of the lungs should be reviewed before starting the procedure. Digital subtraction techniques are used in pulmonary angiography.⁶ Conventional film-screen imaging techniques are no longer used. Selective and superselective catheterization of the pulmonary artery and the magnification technique are used. Digital subtraction angiography (DSA) is performed using a dilute nonionic contrast medium (240 or 270 mg iodine/mL).

Before the procedure, the operator explains the potential risks and benefits of the procedure and availability of alternative tests to the patient, and obtains a written consent. On the day of the procedure, the patient is allowed to take fluids by mouth, and an intravenous line is placed to hydrate the patient. A mild sedative and an analgesic are given 30 minutes before and during the
procedure. During the procedure, electrocardiogram, blood pressure, and oxygen saturation are monitored. Pulmonary angiography can be safely performed as an outpatient procedure. After completion of the procedure, the patient is observed in a radiology recovery room for 2 hours, and ambulation begins. The patient is discharged with an attendant. The attendant is advised to stay with the patient until the following morning and instructed to take certain measures if a complication arises. The patients from the medical intensive care units are usually intubated and attended by the nurse.