Three-step preoperative sequential planning for pulmonary valve replacement in repaired tetralogy of Fallot using computed tomography.

OBJECTIVES: Our goal was to compare results between a standard computed tomography (CT)-based strategy, the 'three-step preoperative sequential planning' (3-step PSP), for pulmonary valve replacement in repaired tetralogy of Fallot versus a conventional planning approach. METHODS: We carried out a retrospective study with unmatched and matched groups. The 3-step PSP comprised the planning of mediastinal re-entry, cannulation for cardiopulmonary bypass (CPB) and the main procedure, using standard 3-dimensional videos. Operative times (skin incision to CPB, CPB time, end of CPB to skin closure and cross-clamp time) as well as postoperative length of stay and in-hospital mortality were compared. RESULTS: Eighty-two patients (49% classical tetralogy of Fallot) underwent an operation (85% with pulmonary homograft) with 1.22% in-hospital mortality. The 3-step PSP (n = 14) and the conventional planning (n = 68) groups were compared. There were no statistically significant differences in the preoperative characteristics. Differences were observed in the total operative time (P = 0.009), skin incision to CPB (P = 0.034) and cross-clamp times (74 ± 33 vs 108 ± 47 min; P = 0.006), favouring the 3-step PSP group. Eight matched pairs were compared showing differences in the total operative time (263 ± 44 vs 360 ± 66 min; P = 0.008), CPB time (123 ± 34 vs 190 ± 43 min; P = 0.008) and postoperative length of stay (P = 0.031), favouring the 3-step PSP group. CONCLUSIONS: In patients with repaired tetralogy of Fallot undergoing pulmonary valve replacement, preoperative planning using a standard CT-based strategy, the 3-step PSP, is associated with shorter operative times and shorter postoperative length of stay.

Caval blood flow distribution in patients with Fontan circulation: quantification by using particle traces from 4D flow MR imaging.

PURPOSE: To validate the use of particle traces derived from four-dimensional (4D) flow magnetic resonance (MR) imaging to quantify in vivo the caval flow contribution to the pulmonary arteries (PAs) in patients who had been treated with the Fontan procedure. MATERIALS AND METHODS: The institutional review boards approved this study, and informed consent was obtained. Twelve healthy volunteers and 10 patients with Fontan circulation were evaluated. The particle trace method consists of creating a region of interest (ROI) on a blood vessel, which is used to emit particles with a temporal resolution of approximately 40 msec. The flow distribution, as a percentage, is then estimated by counting the particles arriving to different ROIs. To validate this method, two independent observers used particle traces to calculate the flow contribution of the PA to its branches in volunteers and compared it with the contribution estimated by measuring net forward flow volume (reference method). After the method was validated, caval flow contributions were quantified in patients. Statistical analysis was performed with nonparametric tests and Bland-Altman plots. P < .05 was considered to indicate a significant difference. RESULTS: Estimation of flow contributions by using particle traces was equivalent to estimation by using the reference method. Mean flow contribution of the PA to the right PA in volunteers was 54% ± 3 (standard deviation) with the reference method versus 54% ± 3 with the particle trace method for observer 1 (P = .4) and 54% ± 4 versus 54% ± 4 for observer 2 (P = .6). In patients with Fontan circulation, 87% ± 13 of the superior vena cava blood flowed to the right PA (range, 63%-100%), whereas 55% ± 19 of the inferior vena cava blood flowed to the left PA (range, 22%-82%). CONCLUSION: Particle traces derived from 4D flow MR imaging enable in vivo quantification of the caval flow distribution to the PAs in patients with Fontan circulation. This method might allow the identification of patients at risk of developing complications secondary to uneven flow distribution. SUPPLEMENTAL MATERIAL: http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.12120778/-/DC1.

Hemodynamic assessment in patients with one-and-a-half ventricle repair revealed by four-dimensional flow magnetic resonance imaging.

We report hemodynamic findings in two patients with pulmonary atresia and intact ventricular septum (PAIVS) after "one-and-a-half ventricle repair" and placement of a bidirectional Glenn shunt using four-dimensional (4D) flow magnetic resonance imaging. Quantification of flow and analysis of flow patterns revealed the hemodynamic "battle" between the right ventricle (RV) and the Glenn shunt. Moreover, with a novel approach we calculated during Glenn anastomosis the flow distribution from the superior vena cava (SVC) to the pulmonary arteries. Our results showed a highly asymmetric flow distribution, with most of the flow from the SVC toward the RV and not to the lungs. The evidence provided by 4D flow demonstrates poor efficiency of this system and suggests that both patients might benefit from adding an artificial pulmonary valve to avoid right heart failure.

Congenital heart disease in children: coronary MR angiography during systole and diastole with dual cardiac phase whole-heart imaging.

PURPOSE: To assess the optimal timing for coronary magnetic resonance (MR) angiography in children with congenital heart disease by using dual cardiac phase whole-heart MR imaging. MATERIALS AND METHODS: The local institutional review board approved this study, and informed consent was obtained from parents or guardians. Thirty children (13 girls; overall mean age, 5.01 years) were examined with a 1.5-T MR system. A free-breathing three-dimensional steady-state free precession dual cardiac phase sequence was used to obtain MR angiographic data during end-systolic and middiastolic rest periods. Vessel length, diameter, and sharpness, as well as image quality of the coronary artery segments, were analyzed and compared by using Bland-Altman plots, linear regression analysis, the t test, and Wilcoxon signed rank tests. RESULTS: Optimal coronary artery imaging timing was patient dependent and different for each coronary artery segment (36 segments favored end systole, 28 favored middiastole). In 15 patients (50%), different segments favored different cardiac phases within the same patient. Image quality and vessel sharpness degraded with higher heart rates, with a similar correlation for end systole (right coronary artery [RCA], 0.39; left main [LM] coronary artery, 0.46; left anterior descending [LAD] artery, 0.51; and left circumflex [LCX] artery, 0.50) and middiastole (RCA, 0.34; LM, 0.45; LAD, 0.48; and LCx, 0.55). Mean image quality difference or mean vessel sharpness difference showed no indication to prefer a specific cardiac phase. CONCLUSION: The optimal cardiac rest period for coronary MR angiography in children with congenital heart disease is specific for each coronary artery segment. Dual cardiac phase whole-heart coronary MR angiography enables optimal coronary artery visualization by retrospectively choosing the optimal imaging rest period.