Hemodynamic Basis for Exercise Intolerance in Right Heart Failure Due to Tricuspid Regurgitation

Abstract

IntroductionTricuspid regurgitation (TR) is associated with symptoms of exertional fatigue and dyspnea, but the hemodynamic basis for functional limitation in TR is not well understood. Elevated pulmonary capillary wedge pressure (PCWP) is often assumed to indicate primary left heart failure, but may be observed with right heart congestion owing to pericardial restraint.Methods and Results15 patients with normal LVEF and grade ≥3 TR (10 women, age 76±7) underwent invasive supine exercise testing with expired gas analysis and were compared to 13 age and sex-matched controls. At rest, TR patients had lower cardiac output (CO) (3.9±1.4 vs 5.1±1.9 L/min; p=0.08), increased right atrial pressure (RAP) (12±5 vs 4±1 mmHg; p<0.0001) and higher PCWP (18±5 vs 9±3 mmHg; p<0.0001). However, left ventricular transmural pressure (LVTMP=PCWP-RAP), which better reflects LV preload independent of right heart and pericardial restraint, was similar in TR and controls (6±3 vs 4±2 mmHg, p=0.11). With exercise, TR patients displayed lower CO (6.3±1.5 vs 10.3±3.3 L/min; p=0.001) and VO2 (7.4±2.6 vs 11.1±4.2 ml/min/kg; p=0.01), with less increase in CO relative to VO2 (Figure 1). TR patients displayed higher PCWP with exercise (Figure 2), but this was solely due to right atrial hypertension (26±8 vs 8±3 mmHg, p<0.0001), as LVTMP fell with exercise, suggesting inadequate left heart filling despite high PCWP (Figure 3).ConclusionFigure 2View Large Image Figure ViewerDownload Hi-res image Download (PPT)Figure 3View Large Image Figure ViewerDownload Hi-res image Download (PPT) IntroductionTricuspid regurgitation (TR) is associated with symptoms of exertional fatigue and dyspnea, but the hemodynamic basis for functional limitation in TR is not well understood. Elevated pulmonary capillary wedge pressure (PCWP) is often assumed to indicate primary left heart failure, but may be observed with right heart congestion owing to pericardial restraint. Tricuspid regurgitation (TR) is associated with symptoms of exertional fatigue and dyspnea, but the hemodynamic basis for functional limitation in TR is not well understood. Elevated pulmonary capillary wedge pressure (PCWP) is often assumed to indicate primary left heart failure, but may be observed with right heart congestion owing to pericardial restraint. Methods and Results15 patients with normal LVEF and grade ≥3 TR (10 women, age 76±7) underwent invasive supine exercise testing with expired gas analysis and were compared to 13 age and sex-matched controls. At rest, TR patients had lower cardiac output (CO) (3.9±1.4 vs 5.1±1.9 L/min; p=0.08), increased right atrial pressure (RAP) (12±5 vs 4±1 mmHg; p<0.0001) and higher PCWP (18±5 vs 9±3 mmHg; p<0.0001). However, left ventricular transmural pressure (LVTMP=PCWP-RAP), which better reflects LV preload independent of right heart and pericardial restraint, was similar in TR and controls (6±3 vs 4±2 mmHg, p=0.11). With exercise, TR patients displayed lower CO (6.3±1.5 vs 10.3±3.3 L/min; p=0.001) and VO2 (7.4±2.6 vs 11.1±4.2 ml/min/kg; p=0.01), with less increase in CO relative to VO2 (Figure 1). TR patients displayed higher PCWP with exercise (Figure 2), but this was solely due to right atrial hypertension (26±8 vs 8±3 mmHg, p<0.0001), as LVTMP fell with exercise, suggesting inadequate left heart filling despite high PCWP (Figure 3). 15 patients with normal LVEF and grade ≥3 TR (10 women, age 76±7) underwent invasive supine exercise testing with expired gas analysis and were compared to 13 age and sex-matched controls. At rest, TR patients had lower cardiac output (CO) (3.9±1.4 vs 5.1±1.9 L/min; p=0.08), increased right atrial pressure (RAP) (12±5 vs 4±1 mmHg; p<0.0001) and higher PCWP (18±5 vs 9±3 mmHg; p<0.0001). However, left ventricular transmural pressure (LVTMP=PCWP-RAP), which better reflects LV preload independent of right heart and pericardial restraint, was similar in TR and controls (6±3 vs 4±2 mmHg, p=0.11). With exercise, TR patients displayed lower CO (6.3±1.5 vs 10.3±3.3 L/min; p=0.001) and VO2 (7.4±2.6 vs 11.1±4.2 ml/min/kg; p=0.01), with less increase in CO relative to VO2 (Figure 1). TR patients displayed higher PCWP with exercise (Figure 2), but this was solely due to right atrial hypertension (26±8 vs 8±3 mmHg, p<0.0001), as LVTMP fell with exercise, suggesting inadequate left heart filling despite high PCWP (Figure 3). ConclusionFigure 3View Large Image Figure ViewerDownload Hi-res image Download (PPT)