Tricuspid Valve Size Relationship to Right Ventricular Volume in Post-operative Tetralogy of Fallot Patients.

In post-operative Tetralogy of Fallot (TOF) patients cMRI data are used for determining right ventricle (RV) dilation to justify the pulmonary valve placement. Echocardiogram analysis of RV volumes has inherent accuracy issues. There are no data exploring the relationship of transthoracic echocardiography tricuspid valve (TV) annulus size and cMRI RV dilation. Retrospective study in post-operative TOF patients. Patients less than 21 years old and with high-quality transthoracic echocardiogram and MRI within 6 months of each other were included. We collected demographic data, type of initial repair, echocardiographic, and cMRI data. A single reviewer measured echocardiogram TV size. Boston z-scores were used. 77 echocardiogram and cMRI pairs were analyzed. Average age was 14 years old. There is not a strong linear relationship between TV z-score and indexed right ventricular end diastolic volume (RVEDVi) (R2 = 0.31). Twenty patients had RVEDVi's of greater than 150 ml/m2. From those 20 patients, 9 patients had a TV z-score of > 2. No patient had a TV z-score > 2 and a normal RVEDVi. For a TV z-score < 2, there was a positive predictive value of 100%, a negative predictive value of 83%, specificity of 100%, and sensitivity of 45%. In our study population, the TV z-score is not sufficient to predict RV dilation. However, TV z-score > 2 has a high positive predictive value for an RVEDVi of > 150 ml/m2. This would suggest that a cMRI should be done if the TV z-score is > 2 on echocardiography.

The Use of Automated Atrial CMR Measures and a Novel Atrioventricular Coupling Index for Predicting Risk in Repaired Tetralogy of Fallot.

Atrial size and function have been recognized as markers of diastolic function, and diastolic dysfunction has been identified as a predictor of adverse outcomes in repaired tetralogy of Fallot (rTOF). This was a retrospective single-center study with the objective of investigating the use of atrial measurements obtained via CMR for predicting outcomes in rTOF patients. Automated contours of the left and right atria (LA and RA) were performed. A novel parameter, termed the Right Atrioventricular Coupling Index (RACI), was defined as the ratio of RA end-diastolic volume to right ventricle (RV) end-diastolic volume. Patients were risk-stratified using a previously validated Importance Factor Score for the prediction of life-threatening arrhythmias in rTOF. Patients with a high-risk Importance Factor Score (>2) had a significantly larger minimum RA volume (p = 0.04) and RACI (p = 0.03) compared to those with scores ≤2. ROC analysis demonstrated RACI to be the best overall predictor of a high-risk Importance Factor Score (AUC 0.73, p = 0.03). Older age at the time of repair and a diagnosis of pulmonary atresia were associated with a larger RACI. Automated atrial CMR measurements are easily obtained from standard CMRs and have the potential to serve as noninvasive predictors of adverse outcomes in rTOF.

Effect of methadone on QTc in infants.

OBJECTIVE: Methadone has been associated with prolongation of the QTc interval (QTc) on electrocardiogram (ECG). In infants, the effects of methadone on the QTc are not well described. Our study's objective is to evaluate the QTc in infants being treated with methadone. METHODS: We conducted a retrospective study in infants receiving methadone. We collected demographic data, methadone dose, and QTc. A blinded-to-disease-state pediatric electrophysiologist determined the QTc. Baseline ECG was defined as an ECG obtained while not on methadone therapy, and QTc on baseline ECG was compared with treatment QTc. A significant change was defined as any absolute QTc greater than 500 or a QTc greater than 460 with an increase from baseline of greater than 40 ms. RESULTS: A total of 44 infants comprised the study population. The mean gestational age was 32.3 ± 5.51 weeks. The median age of initiation was 66 days. The median dose was 0.52 mg/kg/day in oral methadone equivalents. Nine patients were on high dose methadone (>1 mg/kg/day in oral methadone equivalents). The mean baseline QTc was 421 ± 27 and the mean change on methadone was -2 ms. No patient had a QTc greater than 500 on methadone. One patient had a QTc of 467 and 46 ms change from baseline, with no clinically significant impact. CONCLUSION: In our study population, methadone did not significantly prolong the QTc. Further prospective study is warranted to determine the utility and frequency of ECGs in infants receiving methadone.