Passive leg raising: can it help in the diagnosis of pulmonary hypertension due to left heart disease
Authors: Volkov A , Nikolaeva E , Kurmukov I , Nasonov E 
Published: October 2021

Abstract

Pulmonary hypertension (PH) is a frequent hemodynamic condition that is highly prevalent in patients with left heart diseases (LHD). Patients with PH-LHD usually have post-capillary PH, which is now defined by a mean pulmonary arterial pressure (mPAP) of &gt;20 mm Hg and a pulmonary arterial wedge pressure (PAWP) of &gt;15 mm Hg. When assessing PAWP in LHD patients, it must also be acknowledged that pretreatment with diuretics leads to lowering of left-sided filling pressures and thus PAWP, and this bears the potential of misclassifying post- as pre-capillary PH if the PAWP should be lowered to a value below 15 mm Hg. In this context, in cases of borderline PAWP (13–15 mm Hg) a “volume challenge” (500 ml of saline within 5–10 min) has been proposed in order to reverse the diuretic effect and to uncover “occult HFpEF”, but the therapeutic consequences of such testing remain unclear. In acute circulatory failure, passive leg raising (PLR) is a test that predicts whether cardiac output will increase with volume expansion. By transferring a volume of around 300 mL of venous blood from the lower body toward the right heart, PLR mimics a fluid challenge. However, no fluid is infused and the hemodynamic effects are rapidly reversible, thereby avoiding the risks of fluid overload (safety). There are those who believe, that most PH in connective tissue diseases (CTD), espesially systemic sclerosis (SSc) is post-capillary and that many patients are receiving pulmonary vasodilator therapy inappropriately.
The aim of this study to investigate possibility PLR test in the diagnosis of PH due to left heart disease.
PLR test is applied during 77 catheterizations in 69 patients with CTD and PH, among them 14 patients with established PH-LHD and 55 patients with precapillary PH (45 with PAH, 10 with PH, associated with SSc interstitial lung diseases). The diagnosis of PH-LHD was established in the presence of lesions of the left heart (CHD or cardiomyopathy), identified using echocardiography, coronaroangiography and heart MRI.
It was determined that despite approaching a valid difference between the PAWP 12 (7; 14) mm Hg and 8.5 (6; 12) mm Hg, p=0.06), in the PLR test, the level of PAWP increased significantly only in patients with PH-LHD (up to 17 (11; 19) mmHg than precapillary PH (9 (8; 13) mm Hg, p=0.00026). The increase of PAWP was 4 (3; 8) mm Hg and total 1 (0; 3) mm Hg, respectively, differences are valid (p=0.ehab724.19142). The PAWP was measured before the test, and on 5 and 10 minutes during test. It was found that the maximum increase in PAWP occurred 10 minutes from the start of the test.
The ROC analysis of PAWP in this two groups showed the area under the curve was 0.837 (0.737; 0,937), p&lt;0,0001. The cutt-off of the growth of PAWP was 4 mm Hg with a sensitivity of 82% and a specificity of 73%.
Thus, an increase in PAWP more than 4 mm Hg can indicates the presence of PH-LHD in the patient with CTD.

Funding Acknowledgement
Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Ministry of science and higher education, Russian Federation