BACKGROUND:Medical therapy is often prescribed to reduce the rate of aortic dilatation and prevent aortic dissection in patients with bicuspid aortic valve (BAV) despite a lack of evidence. We conducted an anonymous survey to gain insight into Canadian clinical practice regarding medical therapy used to slow the progression of aortic dilatation in patients with BAV. METHODS:A questionnaire was sent to 115 paediatric cardiologists and 18 adult congenital heart disease specialists in Canada. RESULTS:Ninety of 113 paediatric cardiologists (80%) completing the questionnaire reported prescribing medication to reduce the rate of aortic dilatation. Some 75% (61/81) of them reported prescribing medications on the basis of aortic size z scores, and 78% (48/61) considered medication at a z score between ≥ 2 and < 5. The remaining 25% of responders (20/81) reported prescribing medications on the basis of absolute aortic diameter, and 80% (16/20) of them considered initiating medical therapy at an aortic diameter > 40 mm to < 50 mm. For practical purposes, however, 40% of respondents (45/113) would not or rarely consider medical therapy for this indication because of variation in the threshold for initiating treatment. Ten of 14 adult congenital heart disease specialists' responses (71%), reported prescribing medications who were excluded because of missing data. CONCLUSION:The majority of Canadian paediatric cardiologists reported prescribing medications to slow the rate of aortic dilatation in patients with BAV. However, there is heterogeneity in the criteria to prescribe medical therapy. A multicenter randomized controlled trial is needed to establish the role of medical therapy in this patient population.

Objective: We describe a method to measure oxygen consumption (VO2) and pulmonary vascular resistive index (PVRI) based on thermodilution cardiac output in patients with complex mixing circulations. We apply this method to patients with a bidirectional cavopulmonary anastomosis (BDCPA). We compare our measured VO2 with a predicted VO2 based on a formula using height and weight.Methods: We reviewed data based on cardiac catheterization and thermodilution cardiac output in a series of 25 catheterizations in patients with BDCPA. We used this data to measure VO2 and PVRI, and looked for a correlation between the predicted and measured VO2. We also assessed whether any other hemodynamic parameter correlated with measured VO2.Results: There was no significant correlation between the predicted and the measured VO2 (correlation coefficient = -0.258, P= .21). We did find a significant correlation in the difference between the measured and predicted VO2 against the measured VO2 such that at a lower measured VO2 the predictive formula tended to overestimate VO2 and at a higher VO2 the formula underestimated VO2 (correlation coefficient = 0.963, P <. 0001). Body surface area did not correlate with measured VO2 (correlation coefficient = 0.28, P <. 16). Mixed venous oxygen content showed a weak negative correlation with VO2 (correlation coefficient = -0.54, P = .005).Conclusions: An assessment of PVRI that is based on a predicted VO2 is unreliable in this patient population. No hemodynamic parameter correlated well with VO2. The use of a measured VO2 is necessary in determining PVRI in these patients.

Objectives To determine if dexamethasone given to premature infants with bronchopulmonary dysplasia would result in cardiac diastolic dysfunction in early childhood, a topic unstudied in humans.Study design We compared seven children ages 3 to 8 years born at 26 weeks' gestation and given dexamethasone for bronchopulmonary dysplasia with eight gestation-matched and age-matched control children using echocardiography to assess measures of systolic and diastolic function. All dexamethasone patients had resolved hypertrophic cardiomyopathy.Results Dexamethasone patients had the same normal tau and isovolumic relaxation time (24.9 +/- 2.8 and 54.6 +/- 6.3 ms) as control patients (22.1 +/- 3.0 and 48.8 +/- 6.7 ms). Peak A velocities were the same in dexamethasone patients as in control patients (59.5 +/- 15 versus 49.4 +/- 5.8 cm/s, P = .10), resulting in unchanged E:A ratios (1.89 +/- 0.57 versus 2.15 +/- 0.43, P = .22). Peak E velocity and E-wave deceleration times were not different. We found no significant differences in measures of systolic function (heart rate-corrected velocity of circumferential fiber shortening, wall stress, and ejection fraction). Left ventricular mass was the same between the groups confirming resolution of hypertrophic cardiomyopathy.Conclusions These data are consistent with normal myocardial relaxation, suggesting that long-term diastolic function is reassuringly normal in children who received dexamethasone as premature infants with resolution of hypertrophic cardiomyopathy. (J Pediatr 2011; 159: 227-31).