Real-time video kinematic evaluation of the in situ beating right ventricle after pulmonary valve replacement in patients with tetralogy of Fallot: a pilot study

OBJECTIVES: The timing for pulmonary valve replacement (PVR) after tetralogy of Fallot repair is controversial, due to limitations in estimating right ventricular dysfunction and recovery. Intraoperative imaging could add prognostic information, but transoesophageal echocardiography is unsuitable for exploring right heart function. Right ventricular function after PVR was investigated in real time using a novel video-based contactless kinematic evaluation technology (Vi.Ki.E.), which calculates cardiac fatigue and energy consumption.METHODS: Six consecutive patients undergoing PVR at 13.8 +/- 2.6 years (range 6.9-19.8) after the repair of tetralogy of Fallot were enrolled. Mean right ventricular end-diastolic and end-systolic volume at magnetic resonance imaging were 115.6 +/- 16.2 ml/m(2) and 61.5 +/- 14.6 ml/m(2), respectively. Vi.Ki.E. uses a fast-resolution camera placed 45 cm above the open chest, recording cardiac kinematics before and after PVR. An algorithm defines cardiac parameters, such as energy, fatigue, maximum contraction velocity and tissue displacement.RESULTS: There were no perioperative complications, with patients discharged in satisfactory clinical conditions after 7 +/- 2 days (range 5-9). Vi.Ki.E. parameters describing right ventricular dysfunction decreased significantly after surgery: energy consumption by 45% [271 125 +/- 9422 (mm/s)(2) vs 149 202 +/- 11 980 (mm/s)(2) , P = 0.0001], cardiac fatigue by 12% (292 671 +/- 29 369 mm/s(2) vs 258 755 +/- 42 750 mm/s(2), P = 0.01), contraction velocity by 54% (3412 +/- 749 mm/s vs 1579 +/- 400 mm/s, P = 0.0007) and displacement by 23% (27 +/- 4 mm vs 21 +/- 4 mm, P = 0.01). Patients undergoing PVR at lower end-diastolic volumes, had greater functional recovery of Vi.Ki.E. parameters.CONCLUSIONS: Intraoperative Vi.Ki.E shows immediate recovery of right ventricular mechanics after PVR with less cardiac fatigue and energy consumption, providing novel insights that may have a prognostic relevance for functional recovery.