Functional state of peripheral and microcirculatory blood flow in patients with pulmonary hypertension on the background of systemic connective tissue diseases

Aim. To study the functional state of peripheral and microcirculatory blood flow in patients with pulmonary hypertension associated with systemic connective tissue diseases (PH-SCTD). Material and methods. The study included 22 patients (50,1±14,7) with PH-SCTD I–III functional class. 18 patients had systemic scleroderma, 3 – systemic lupus erythematosus, and 1 patient suffered from rheumatoid arthritis. The control group (CG) comprised 25 healthy volunteers (39,3±10). The studies were performed using finger photoplethysmography (FPG), laser Doppler flowmetry (LDF), and capillaroscopy (CS). Results. According to the FPG data, patients with PH-SCTD relative to CG have lower values of occlusion index in the amplitude of 1,51±0,37 and 2,28±0,46 respectively (<0.05). According to LDF data, signs of venular plethora are observed in patients with PH-SCTD, which is manifested by an increase in the amplitude of respiratory-induced fluctuations in blood flow to 0,17±0,11 (PU) versus 0,13±0,07 (PU) in CG (<0.05), an increase in the constrictor reaction in the cold test was 56,4±16,8 % and 42,1±17,9 % (<0.05) and a venous occlusion test was 56,8±18,7 % and 45,2±17,9 % (<0.05), respectively. According to CS data, patients with PH-SCTD have a noticeable increase in the degree of hydration of the interstitial space, which manifests itself in an increase in the size of the pericapillary space to 160,8±37,3 μm against 114,1±17,4 μm in the CG (<0.00001). Conclusions. In patients with PH-SCTD, all regulatory mechanisms and structural components of microvessels, including endothelial and smooth muscle cells, are involved in the pathological process, which is manifested by an increase in the constrictor activity for all types of stimuli and a violation of the filtration-reabsorption mechanism of metabolism.