J. Tim Marcus, Berend E. Westerhof, Joanne A. Groeneveldt, Harm Jan Bogaard, Frances S. de Man, Anton Vonk Noordegraaf
European Respiratory Journal 2019; DOI: 10.1183/13993003.00625-2019
Vena cava (VC) backflow is a well-recognized clinical hallmark of right ventricular (RV) failure in pulmonary arterial hypertension (PAH). Backflow may result from tricuspid regurgitation during RV systole or from impaired RV diastolic filling during atrial contraction. Our aim was to quantify forward and backward flow in the VC and to establish the main cause in PAH.
In 62 PAH patients, cardiac magnetic resonance measurements provided volumetric flows (mL·s−1) in the superior and inferior VC; time-integration of flow gave volume. “Backward fraction” was defined as the ratio of backward and forward volume in the VC, expressed as percentage. Time of maximum VC backflow was expressed as percentage of the cardiac cycle. RV volumes and aortic stroke volume were determined. Right heart catheterisation gave RV and right atrial pressures. RV end-diastolic stiffness was determined with the single beat method.
The backward fraction was 12 (IQR:3–24)% and larger than 20% in 21 patients. Maximum backflow occurred at near 90% of the cardiac cycle, coinciding with atrial contraction. The backward fraction was associated with maximal right atrial pressure (Spearman's r=0.77), RV end-diastolic stiffness (r=0.65), RV end-diastolic pressure (r=0.77), and was negatively associated with stroke volume (r=–0.61; all p<0.001).
Significant backward flow in the VC was observed in a large group of PAH-patients and occurred mostly during atrial contraction as a consequence of impaired RV filling due to RV diastolic stiffness. Backward flow due to tricuspid regurgitation was of significance in only a small minority of patients.
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Conflict of interest: Dr. Marcus reports personal fees from consultant for Actelion Pharmaceuticals, outside the submitted work.
Conflict of interest: Dr. Westerhof reports grants from The Netherlands Organisation for Scientific Research, during the conduct of the study.
Conflict of interest: Dr. Groeneveldt has nothing to disclose.
Conflict of interest: Dr. Bogaard has nothing to disclose.
Conflict of interest: Dr. de Man has nothing to disclose.
Conflict of interest: Dr. vonk noordegraaf reports personal fees from actelion and msd outside the submitted work.