Despite the increasing use of Doppler echocardiographic (DE) techniques to determine pulmonary arterial pressure in the neonate undergoing intensive care, there have been no studies comparing their repeatability in this population. Our objective was to compare the repeatability of four such techniques in neonates. The study was conducted in two regional neonatal units serving the North East of England. Group A (repeatability between observers): Two experienced observers performed detailed DE examinations, one directly after the other. Group B (within observer repeatability/temporal variability): One observer performed two examinations 1 hour apart. Group A comprised 15 preterm babies (26-36 weeks' gestation, 975-2915 g), most with mild respiratory failure; 4 healthy term babies; and 7 with congenital heart disease, in whom tricuspid regurgitation (TR) only was measured. Their ages were 18 hours to 12 days. Group B comprised 11 babies aged 12-64 hours with moderate to severe respiratory failure; 10 were preterm (26-36 weeks, 785-2800 g). We recorded four measurements: (1) Peak velocity of TR in m/s; (2) peak left-to-right ductal flow velocity (PDAmax in m/s); (3) TPV/RVET ratio; and (4) PEP/RVET ratio, where TPV = time to peak velocity at the pulmonary valve, PEP = right ventricular preejection period, and RVET = right ventricular ejection time. The Bland-Altman analysis was used to produce the coefficient of repeatability (CR: 95% confidence limits of repeatability), also expressed as a repeatability index (CR/mean value) and as a number of "confidence steps"-a measure of sensitivity of the technique to hemodynamic change (range of values within the population/CR). Between-observer and within-observer repeatabilities were similar. Within-observer CR and index (%) results were for TR +/- 0.26 m/s (9%); for PDAmax, +/- 0.48 m/s (39%); TPV/RVET 0.1:1.0 (34%), PEP/RVET 0.12:1.00 (36%). TR and PDAmax had the largest number of confidence steps in the expected range of values (TR 8.5; PDA max 6.5; TPV/RVET 3.2; PEP/RVET 3.2). The most repeatable technique was TR, but PDAmax would also be useful for a serial study owing to the potential for large change. Systolic time interval ratios were less repeatable and likely to be less sensitive indicators of hemodynamic change.

Doppler and direct measurements of right ventricle to right atrial pressure drop were made during cardiac catheterisation on 28 occasions in 26 infants with congenital heart disease. Age was 10 days to 12 months (median 4 5 months), and weight was 3-1 to 9-0 kg (median 4*7 kg). We measured peak velocity of The tricuspid valve is obviously much smaller in babies, and although the area of regurgitation cannot be measured accurately, it is logical to assume that this is also much smaller; and probably less than 3-5 mm in diameter in the newborn, particularly when the regurgitation is trivial. The combination of low velocity (less than 3 m/sec), which is common in the newborn,'2 13 with small regurgitant area could theoretically lead to significant underestimation of the true pulmonary arterial pressure.The original aims of this study were to investigate the validity and repeatability of the method in the newborn. However, as neonatal cardiac catheterisation is now rare in paediatric cardiology, the study group was expanded to include babies up to 1 year of age. The aims of this study were therefore: (1)

TyneSUMMARY The variability ofDoppler echocardiographic estimation of cardiac output at the aortic orifice was investigated in eight healthy subjects. Cross sectional echocardiograms of the aortic orifice and aortic Doppler velocities were recorded and measured by four echocardiographers. Between subject variability was significantly larger than within subject variability for all variables. Variability owing to different echocardiographers and different measurement times was small compared with total variability. Coefficients ofvariation for aortic annular diameter, aortic velocity integral, and heart rate were 4a 1 %, 6-4%, and 5 0% respectively.

Right ventricular dilatation is an infrequent finding at fetal echocardiography. Previous studies have documented an association with aortic coarctation. However, there are associations with other congenital abnormalities. We reviewed our experience of fetal right heart dilatation in order to recognize concurrent anomalies and to assess the outcome of the affected fetuses. We studied all fetuses with right ventricular dilatation over a 5-year period. We documented associated cardiac and noncardiac lesions, and outcome data were assessed in terms of the number of fetuses that were born live and the number surviving to 2 months of age. Forty-three fetuses with right heart dilatation were seen. Fifteen had associated cardiac abnormalities: most commonly coarctation (n = 4) and VSD (n = 4). Seven had associated noncardiac abnormalities. There were seven fetuses who also had chromosomal abnormalities. In total, there were three terminations of pregnancy, four intrauterine deaths, one stillbirth and 35 live-births. Twenty-eight were alive at 2 months of age (70% of the nonterminated pregnancies). Fetal right heart dilatation is frequently associated with both cardiac and noncardiac congenital abnormalities. Our outcome figures suggest a guarded prognosis be given during counseling of parents of fetuses with right heart dilatation.

SUMMARY The haemodynamic responses to isometric exercise of eight recipients of orthotopic heart transplants and eight healthy controls were studied. Each performed sustained exercise at 30% of maximal voluntary contraction for three minutes on a handgrip dynamometer. Cardiac output was measured by combined Doppler and cross sectional echocardiography before exercise and every 30 seconds during and after exercise. In the controls cardiac output and blood pressure increased significantly owing to an increase in heart rate with no change in stroke volume. In the transplant group cardiac output, heart rate, and stroke volume remained unchanged throughout exercise.In contrast with its response to dynamic exercise the denervated human heart is unable to increase cardiac output during isometric exercise. The pressor response that occurs is mediated via an increase in peripheral vascular resistance.Although reinnervation of the transplanted heart has been well documented after orthotopic transplantation of the canine heart,' the transplanted human heart seems to remain both functionally and anatomically denervated indefinitely.2 Studies in normally innervated human hearts have shown that isometric exercise results in significant increases in cardiac output, heart rate, and mean blood pressure without changes in stroke volume, ventricular dimensions, or myocardial contractility." Although the transplanted denervated heart is able to maintain a relatively normal cardiac output during dynamic exercise' through the Frank-Starling mechanism, it is difficult to envisage how it can produce an appropriate increase in cardiac output during semisupine static exercise.Cardiac output can be calculated from blood velocity in the ascending aorta, measured by Doppler ultrasound, combined with aortic orifice area, measured by cross sectional echocardiography.9"0 The technique is reproducible" 12 and allows quick, non-invasive measurements of cardiac output both at rest and during supine and upright exercise."'5 Left ventricular size and performance can be accuratelyRequests for reprints to Dr S S Furniss, Regional Cardiothoracic Centre, Freeman Hospital, Newcastle upon Tyne NE7 7DN.Accepted for publication 29 November 1988 measured by M mode echocardiography.'6 '7 We used these techniques to investigate the haemodynamic changes during handgrip isometric exercise in recipients of orthotopic heart transplants and in controls. Patients and methodsEight recipients of orthotopic heart transplants (six men) were recruited. The details of the group were as follows: mean (SD) age 40 (10) years, mean (SD) height 1-71 (0-08) m, mean (SD) weight 64-8 (9.5) kg.All patients were clinically and functionally well with no clinically significant biochemical or haematological abnormality at the time of the study.Mean haemoglobin was 12 3 g/l and mean creatinine clearance was 58 ml/min. The mean length of survival after transplantation was 11 (range 5-21) months and all patients were receiving standard immunosuppressive treatment (prednisolone, azath...