Intrathoracic pulmonary artery catheter allocation in the background of left atrial dilatation

AIM: The aim of the study was to find out whether dilatation of the left atrium (LA) influences the intra-thoracic distribution of thermodilution pulmonary artery (TPA) catheter in either branch of pulmonary artery and compare the measured cardiac output. METHODS: In this prospective study of 132 consecutive patients in a university hospital setting, LA size and ejection fraction was assessed by echocardiography, in the preoperative period. In 66 patients posted for coronary artery bypass grafting (Group 1), a standard anaesthesia regimen was used and TPA catheter was floated through the right internal jugular. In another 66 patients of long-standing mitral stenosis for mitral valve repair/replacement (Group 2), TPA catheters were similarly floated. Intrathoracic placement of the tip of the TPA catheter into the right or left pulmonary artery (PA) was confirmed on chest X-ray. TPA catheter length to its wedging, intra-arterial pressure, heart rate, PA pressure, pulmonary artery wedge pressure (PAWP) and cardiac output by thermodilution technique were noted. RESULTS: Leftwards TPA catheter placement was significantly (p<0.001) more frequent (71%) in mitral stenosis patients (group 2) than the CABG (group 1), (18%). On regrouping the observations of rightwards placed TPA (Group R) and leftwards placed TPA (Group L), we observed that large LA (> or = 25 mm3/m2) body surface area (BSA) and high PAWP (> or = 20 mmHg) was associated with significantly (p<0.001) higher incidence of leftwards TPA catheters. Positive predictive value of both the factors in combination was significantly higher (96%) than individual factors large LA (81%) and high PAWP (88%). CONCLUSION: In long standing mitral stenosis, left atrium enlargement, with high PAWP and the hypokinesia of left atrium (atrial fibrillation) likely to influence the angulation of left PA with main PA and so the predominant entry of TPA catheter tip in left PA.