Cross-sectional echocardiography was performed on 108 healthy children (7 days – 17 years old) and 55 children (6 months - 16.5 years old) with interatrial communication. Right ventricular end-diastolic volume, end-systolic volume, stroke volume, ejection fraction, muscle volume, and the ratio of muscle to cavity were calculated on the basis of outlined cavity and myocardium of an apical fourchamber view.

In the normal subjects right ventricular end-diastolic volume, end-systolic volume, stroke volume and muscle volume correlated with body surface area (end-diastolic volume: y=12.5x+7.8x2, r=0.99; end-systolic volume: y=4.8x+3.6x2, r=0.98; stroke volume: y=7.7x+4.2x2, r=0.98; muscle volume: y=14.1x+2.9x2, r=0.97), muscle/cavity ratio (0.85±0.17) and ejection fraction (58.9 ± 6.2%) were unrelated to body surface area. In the subjects with interatrial communication, the right ventricular volumes were significantly larger (p<0.001) than the normal values with a linear relationship to the ratio of pulmonary to systemic flows.

Right ventricular volumes can be determined in normal children with acceptable repeatability using a standard apical four-chamber view. The growth related normal values provide a basis for future quantitative studies.

Objective: To assess the impact of a computerised system to support decision-making concerning the management of warfarin used in maintenance of anti-coagulation. Design: Retrospective case series study comparing manual and computerised records of prescribing. Setting: A tertiary paediatric cardiology department in a teaching hospital. Participants: The 26 children receiving warfarin to maintain anticoagulation at the time of introduction of a computerised system to support decision-making. Interventions: A rules-based computerised system to support decisions, based on existing departmental guidelines, for management of anticoagulation using warfarin was introduced to aid prescribing physicians. Main outcomes: We assessed the stability of the International Normalised Ratio, along with the number of checks made of the ratio, and the adjustments of dosage. Dosages, and recheck interval prescriptions, were compared to the guidelines established by our department. Results: We compared 274 prescriptions made manually, and 608 made using the computerised system to support decision-making, covering periods of 4, and 11, months respectively. The mean proportion of time spent by the patients within their target range for the International ratio was maintained during the period studied, at 76 percent versus 79 percent (p = 0.79). The median number of checks of the ratio made for each patient over a period of 28 days was unchanged, at 1.9 versus 2.1 (p = 0.58). There was a significant change in prescribing practices, which more closely followed the departmental guidelines. Conclusion: The introduction of a computerised system to support decision-making maintained the stability of the International ratio using warfarin, without increasing the number of checks or adjustments of dosages, in a point-of-care service for anticoagulation in children.

We describe the electrophysiological studies undertaken in four patients with atrioventricular nodal reentry tachycardia in the setting of concordant atrioventricular and discordant ventriculo-arterial connections (transposition). Radiofrequency ablation was attempted in three, all with success. Clear evidence of dual antegrade pathways through the atrioventricular node was present in only one of the four, but other characteristics of discrete fast and slow pathways into the atrioventricular node were present in all. Atrioventricular nodal reentry tachycardia was inducible in all. In the three patients in whom ablation was attempted, the application of radiofrequency energy to the low medial regions of the systemic venous atrium (morphologically left) consistently caused junctional accelerated rhythm, but these lesions were not successful in eliminating the tachycardia. Successful radiofrequency ablation required a retrograde approach to the region of the slow pathway in the pulmonary venous atrium (morphologically right).

After repair of an atrioventricular septal defect with common atrioventricular junction in a 2-month-old girl, rapid atrial tachycardia, in combination with junctional ectopic tachycardia, led to severe postoperative cardiovascular compromise. Intercurrent runs of ectopic atrial tachycardia made atrial pacing impossible, despite high doses of intravenous amiodarone. Following the addition of flecainide to the infusion, we were able to control the rhythm, and when combined with atrial pacing, this led to an immediate haemodynamic improvement. Treatment of refractory supraventricular tachycardias with amiodarone combined with flecainide can be very effective in the setting of postoperative cardiac intensive care.

Aims: To determine the accuracy of data relating to pulmonary vascular resistance data in patients with a bidirectional Glenn anastomosis as calculated using predicted versus measured uptake of oxygen. Methods: We studied retrospectively the data from 33 patients with a bidirectional Glenn anastomosis who underwent cardiac catheterisation prior to surgery to complete the Fontan circulation. Their weight ranged from 5.4 to 51.7 kg, and they were aged up to 12 years. Uptake of oxygen was measured using the Deltatrac II metabolic monitor. From the calculated indexed pulmonary vascular resistance, cases were stratified according to the risk of failure of the subsequent Fontan circulation. The six patients with a resistance of greater than 4 Um2 were deemed at high risk, the six with a resistance from 3 to 4 Um2 at moderate risk, and the 21 patients with a resistance less than 3 Um2 at low risk. Uptake of oxygen was also estimated from the predictive formulas of Lindahl, Lundell et al. and LaFarge and Miettinen. The indexed resistance was similarly calculated using these formulas and a comparable stratification of risk made from this data. Results: The predicted values for uptake of oxygen were consistently higher than those measured, leading to an underestimation of indexed resistance, with mean difference between −0.62 and −1.57 Um2. This difference resulted in misclassification of between five and nine of the 12 patients considered at moderate or high risk as being at low-risk. No other haemodynamic data could reliably separate the subjects deemed at low-risk from those considered to be at high-risk. A transpulmonary gradient of greater than 7 mm of mercury was found to be 100 percent specific for elevated indexed resistance, but only 60 percent sensitive. Conclusions: In patients with bidirectional Glenn anastomoses, all formulas based on predictive uptake of oxygen lead to underestimation of the true indexed pulmonary vascular resistance, to an extent that could significantly influence clinical decision-making. The transpulmonary gradient is not a reliable surrogate for indexed pulmonary vascular resistance.