Possible causes of dissociation between pulmonary embolism volume and right ventricular dysfunction degree

Aim. To study possible causes of the dissociation between pulmonary embolism volume and right ventricular (RV) dysfunction degree. Material and methods. The main group included 37 patients with pulmonary embolism (PE); the comparison group consisted of 15 patients with coronary heart disease (CHD) and NYHA functional class (FC) I–II heart failure (HF). All participants underwent ventilation-perfusion lung scintigraphy, gated blood pool single photon emission computed tomography (GBPS), and the measurement of plasma levels of stable NO metabolites, endotelin‑1, and 6‑keto-prostaglandin (Pg) F1α. Results. In PE patients, RV contractility parameters were significantly lower than those in the comparison group. Among patients with moderate PE volume (3–7 bronchopulmonary segments), no correlation was observed between the number of hypoperfused segments and RV dysfunction degree. In PE patients, compared to the comparison group, plasma levels of endotelin‑1, stable NO metabolites, and stable prostacyclin metabolite 6‑keto-Pg F1α were significantly higher. Conclusion. In PE patients, the most important GBPS parameters of RV dysfunction included reduced ejection fraction, stroke volume, peak ejection rate, and mean filling rate. The dissociation between PE volume and RV dysfunction degree could be caused by disturbed humoral regulation of pulmonary vascular tone.