The role of epicardial echocardiography in the measurement of transvalvular flow velocities during aortic valve replacement.

OBJECTIVE: The purpose of this study was to compare transvalvular flow velocities obtained by transesophageal echocardiography and epicardial echocardiography (EE) during aortic valve replacement (AVR). DESIGN: Prospective observational study. SETTING: University hospital. PARTICIPANTS: Patients undergoing AVR for aortic stenosis. INTERVENTIONS: After institutional review board approval, 17 patients undergoing AVR consented. Deep transgastric (deep TG LAX) and transgastric long-axis (TG LAX) views and epicardial aortic valve long-axis views (S8 probe) were obtained on a SONOS 5500 (Phillips Medical Systems, Bothell, WA) before and after AVR. Transvalvular flow velocity and velocity time integral (VTI) were recorded via each technique. Measurements were made offline by 2 independent reviewers. Agreement between measurements made by different views was evaluated by using Bland-Altman analysis. MEASUREMENTS AND MAIN RESULTS: The epicardial probe was well tolerated. Quality images were obtained in all patients with TEE and 30 of 34 studies via epicardial scanning. The mean bias for peak velocities derived through EE and deep TG LAX was 96.3 cm/s (95% confidence interval [CI], 51.1-141.4) before AVR and 58 cm/s (95% CI, 32.4-83.7) after AVR. The mean bias for peak velocities between EE and TG LAX was 70 cm/s (95% CI, 31.1-108.9) before and 84.7 cm/s (95% CI, 55.6-113.7) after AVR. Similar results were obtained for VTI. CONCLUSIONS: Peak transaortic valve velocities and VTI measured with epicardial echocardiography are higher in comparison to measurements via TEE in patients undergoing AVR. The precise role of epicardial echocardiography in the comprehensive echocardiographic examination of patients undergoing aortic valve replacement needs further evaluation.

Cardiac output monitoring using a brachial arterial catheter during off-pump coronary artery bypass grafting.

OBJECTIVE: To investigate the accuracy of cardiac output measurements by transpulmonary thermodilution and pulse contour analysis using a brachial arterial catheter. STUDY DESIGN: Criterion standard study. SETTING: University hospital, single institution. POPULATION: Twenty-three adult patients undergoing off-pump coronary artery bypass grafting. MEASUREMENTS AND MAIN RESULTS: Cardiac output was measured with a thermistor-tipped brachial arterial catheter using pulse contour analysis (COpc) and transpulmonary thermodilution (COba), which serves to calibrate COpc in the system tested. Both methods were compared separately with standard pulmonary artery thermodilution (COpa). COba was closely correlated with COpa (r = 0.93, p < 0.001). Bland-Altman analysis showed a bias of 0.91 L/min with limits of agreement of +/-0.98 L/min. COpc was also closely correlated (r = 0.80, p < 0.001) with COpa and was found to have a bias of 1.08 L/min with limits of agreement of +/-1.50 L/min. During the surgical procedure, changes in COpa from baseline were closely correlated with changes in COba (r = 0.90, p < 0.01) and COpc (r = 0.81, p < 0.01). CONCLUSIONS: The brachial arterial access allows a reliable assessment of cardiac output by transpulmonary thermodilution and pulse contour analysis in patients undergoing off-pump coronary artery bypass grafting.