Quantitative assessment of pulmonary blood flow redistribution in the classification of group 1 and group 4 pulmonary hypertension.

BACKGROUND

All patients with pulmonary hypertension (PH), without left heart disease or lung diseases, need further distinguishing between pulmonary arterial hypertension (PAH) and chronic thromboembolic pulmonary hypertension (CTEPH). This study aimed to investigate the value of quantitative assessment of pulmonary blood flow redistribution in further classification.

METHODS

Forty-six patients who underwent echocardiography and computed tomography pulmonary angiography at The First Affiliated Hospital of Xi'an Jiaotong University were included in this cross-sectional study, and all patients were categorized into a non-PH group (18 cases), a PAH group (12 cases), and a CTEPH group (16 cases). The diameter of the left ventricle and right ventricle were measured. The volumes of the main, right, and left pulmonary arteries were calculated. The total blood volume (TBV), the blood volume of vessels at the cross-section with an area <5 mm (BV5), between 5 and 10 mm (BV5-10), and >10 mm (BV10), and the blood volume of the pulmonary arteries and veins, were quantitatively assessed. TBV, BV5, BV5-10 and BV10 were all normalized to the volume of the corresponding lung or lobe.

RESULTS

The diameter of the right ventricular, and the volumes of the main pulmonary artery, right pulmonary artery, and left pulmonary artery were not significantly different between the PAH and CTEPH group (P>0.05). The BV10 of CTEPH were significantly lower than those of the PAH group for the whole lung (32.69‰±13.53‰ 18.73‰±6.10‰; =6.234; P=0.004), right lung (29.06‰±15.01‰ 9.99‰±4.26‰; =10.819; P<0.001), left lung (32.41‰±15.83‰ 18.32‰±6.43‰; =4.322; P=0.020), right upper lobe (RUL) (22.26‰±12.07‰ 7.90‰±2.92‰; =8.991; P=0.001), right middle lobe (20.72‰±9.95‰ 7.54‰±5.32‰; =7.117; P=0.002), right lower lobe (RLL) (31.55‰±18.22‰ 12.40‰±5.99‰; =8.098; P=0.001), left upper lobe (28.23‰±14.82‰ 14.95‰±5.24‰; =5.630; P=0.007) and left lower lobe (31.04‰±14.85‰ 20.04‰±8.58‰; =2.477; P=0.096). The arterial TBV (42.18‰±13.67‰ 27.76‰±7.96‰; =6.544; P=0.003), arterial BV10 (18.19‰±7.29‰ 9.36‰±3.83‰; =7.758; P=0.001), venous TBV (35.58‰±16.35‰ 25.01‰±4.79‰; =3.727; P=0.033), and venous BV10 (14.50‰±7.09‰ 9.36‰±2.76‰; =3.676; P=0.034) were also significantly lower in the CTEPH group than those of the PAH group. Age [95% confidence interval (CI): 0.011 to 0.082; P=0.013] and BV10 of the RUL (95% CI: -0.102 to -0.004; P=0.034) were the most discriminative parameters, with an area under the curve of 0.950 in distinguishing PAH and CTEPH (P<0.05).

CONCLUSIONS

Pulmonary vessel volume increased in PAH, particularly in larger-caliber vessels and the pulmonary artery, while it decreased in CTEPH, especially in larger-caliber vessels and the RLL.