ofM mode derived indices

Objective-To compare M mode derived indices of left ventricular performance obtained with transthoracic and transoesophageal echocardiography in children with congenital heart disease. Design-Transthoracic and transoesophageal M mode echocardiograms were obtained under general anaesthesia before cardiac catheterisation. Recordings were digitised by dedicated software. Indices of cavity dimension and left ventricular wall dynamics were compared. Patients-16 unselected patients with congenital heart disease. Results-Group data for simple measurements of ventricular dimension and wall thickness were similar with the two techniques and had acceptable coefficients of repeatability, but there were considerable individual differences. Correlation was poor with unacceptable repeatability for derived indices of cavity and ventricular wall dynamics. Conclusion-Both transthoracic and transoesophageal echocardiography can be used to obtain M mode derived indices of left ventricular performance but the resultant measurements are not directly comparable, presumably because of regional non-uniformity of function. (Br Heart J 1992;87:485-7) With increasing availability and reduction in size of transoesophageal echocardiographic equipment transoesophageal echocardiography is rapidly becoming the imaging technique of choice in children in operating theatres, intensive care units, and during interventional cardiac catheterisation. The accurate assessment of ventricular performance is clearly important in all of these areas. Until now the assessment of left ventricular performance with M mode echocardiography has largely been restricted to recordings obtained through the transthoracic window. It should be possible, however, to obtain potentially comparable information during transoesophageal echocardiography and the purpose of this study was to compare indices of left ventricular performance obtained from children with congenital heart disease undergoing simultaneous transthoracic and transoesophageal echocardiography. Patients and methods Twenty two unselected children with congenital heart disease were studied. All were undergoing cardiac catheterisation with general anaesthesia as part of their preoperative assessment. The transthoracic M mode recordings were unsatisfactory in six patients leaving 16 in whom comparative data were available. The ages of these patients ranged from three months to 17 years (median five years and four months) and their weight ranged from 4-9-55-4 kg (median 19 kg). Table 1 gives the full sequential diagnosis for each of the 16 patients. The procedure was identical in all patients. After endotracheal intubation a transoesophageal probe was inserted. In children over 12 kg a standard adult sized 5 mHz single plane phased array transducer was used. In three patients a developmental paediatric probe was used. This had a shaft diameter of 6 mm and a switchable 7-5-5 mHz single plane phased array transducer mounted at its tip. Both probes were interfaced with a Hewlett-Packard sonus 1000 ultrasound system. A transoesophageal gastric short axis view of the left ventricle was taken from each patient. Left ventricular M mode recordings were taken across its maximal dimension at the level of the mitral valve tips. As soon as possible after this, with the transoesophageal probe in place, a transthoracic recording of the left ventricular M mode, again at the level of the mitral valve leaflet tips, was obtained in either parasternal short axis or long axis sections. Care was taken to maintain all haemodynamic variables unchanged throughout Table I Diagnoses of individual patients