Correct!
2. Catheter pulmonary angiography
One could make an argument that CT pulmonary angiography should be the next appropriate step, but this test was not offered as a choice. When chronic thromboembolic disease is a leading diagnostic consideration, 133Xe-ventilation – 99mTc-perfusion scintigraphy is often the next recommended test, serving as a screening study. If this study is abnormal, then typically catheter pulmonary angiography is recommended for the diagnosis and confirmation of thromboembolic disease. Catheter pulmonary angiography has the major advantage of combining the assessment of hemodynamic parameters with imaging to allow both diagnosis and determination of the severity of chronic thromboemboli and to as a baseline to assess therapeutic interventions. Thoracic MRI and MRA can also establish the diagnosis of chronic thromboembolic disease, and recent advancement in MR techniques have allowed the accuracy of thoracic MRI and MRA for the diagnosis of chronic thromboembolic disease to approach that of CT pulmonary angiography. If CT pulmonary angiography were considered in this patient, but was not feasible for some reason, then thoracic MRI and MRA would potentially be a correct choice and could serve as an alternative to catheter pulmonary angiography. Echocardiography is a useful test for the assessment of possible chronic thromboembolic disease as it allows determination of right heart function and estimation of pulmonary hypertension, and would be a reasonable test to obtain, but a bubble study to assess for right-to-left shunt is not specifically required in this patient.
The patient underwent catheter pulmonary angiography (Figure 4), which showed the mean pulmonary artery pressure to be 20 mmHg.
Figure 4. Catheter pulmonary angiography of the right pulmonary arterial system in the arterial (A) and venous (B) phases shows no specific abnormalities. Catheter pulmonary angiography of the left pulmonary arterial system in the arterial (C) and venous (D) phases shows complete obstruction of the left interlobar and lower lobe arterial system (arrows) with absent perfusion to the left lower lobe (between arrowheads). The left superior pulmonary vein is well visualized (double arrowhead) but the left inferior pulmonary vein is not, owing to delayed contrast transit from the left lower lobe pulmonary arterial obstruction.
There was lack of pulmonary arterial filling at the left apex and left lower lobe (Figure 4C and D), corresponding to the locations of perfusion defects seen at 133Xe-ventilation – 99mTc-perfusion scintigraphy. Difficulty accessing the left pulmonary artery was noted during the study. The right pulmonary artery showed no evidence of occlusion, webs, or tortuosity to suggest chronic thromboembolic disease.
Which of the following represents the most appropriate next stepfor the managementof this patient? (Click on the correct answer to proceed to the seventh of nine pages, the correct answer has two large videos and may be slow to load)