Comparison of MR flow quantification in peripheral and main pulmonary arteries in patients after right ventricular outflow tract surgery: A retrospective study.

PURPOSE: To compare the quantification of pulmonary stroke volume (SV) by phase contrast magnetic resonance (PC-MR) in the main pulmonary artery (MPA) to the sum of SVs in both peripheral pulmonary arteries (PPA) in different right ventricular (RV) outflow pathologies. MATERIALS AND METHODS: Pulmonary SV was determined by PC-MR in the MPA and the PPA in healthy individuals (H, n = 54), patients after correction for tetralogy of Fallot with significant pulmonary regurgitation and without pulmonary or RV outflow tract stenosis (PR, n = 50), and in patients with RV outflow tract or pulmonary valve stenosis (PS, n = 50). Resulting SVs were compared to aortic SV in the ascending aorta. RESULTS: Mean age was similar between the groups: H 28 ± 17 vs. PR 24 ± 11 vs. PS 22 ± 10 years. Bland-Altman analyses revealed in all groups a relatively small systemic (bias) but large random error (limits of agreement) for pulmonary SV determined in the MPA as compared to summed SVs in the PPA. The largest limits of agreement were present in PS patients: H: MPA 3.9% (-11, + 19) vs. PPA 0.4% (-15, + 15); PR: MPA 5.2% (-25, + 36) vs. PPA 0.6% (-24, + 26); PS: MPA 5% (-36; + 46), PPA -0.03% (-34, + 35). CONCLUSION: The accuracy of PC-MR in the MPA is reasonable; however, a large random error (precision) is observed that is most pronounced in PS patients. This potential error should be taken into consideration when interpreting MPA flow measurements. LEVEL OF EVIDENCE: 3 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2017;46:1839-1845.

Evolution of right ventricular size over time after tetralogy of Fallot repair: a longitudinal cardiac magnetic resonance study.

AIMS: It is commonly believed that pulmonary regurgitation (PR) after surgical repair of tetralogy of Fallot (TOF) leads to progressive right ventricular (RV) enlargement. However, progressive RV dilatation has never clearly been documented in this patient population. Therefore, we studied the size of the RV over time in patients after surgical TOF repair. METHODS AND RESULTS: Fifty-one consecutive patients after surgical TOF repair underwent at least two cardiovascular magnetic resonance (CMR) exams using a single CMR scanner. Patients with RV outflow tract obstruction, interventions other than the initial repair and CMR exams with use of sedation were excluded. Three subgroups with different repair techniques were studied: transannular patch repair [n = 22, age 17 ± 10 years], subvalvular patch repair [n = 15, age 22 ± 8 years], or non-patch repair/infundibulectomy (n = 14, age 28 ± 11 years). Right ventricular end-diastolic volume index (RVEDVI) and PR fraction did not change during the 37 ± 21 months follow-up between first and last CMR in the whole group (RVEDVI: 118 ± 23 mL/m2 vs. 119 ± 23 mL/m2, P = 0.720; PR fraction: 33% (23-40%) vs. 32% (24-39%), P = 0.268). RVEDVI remained stable in all subgroups (transannular patch: 120 ± 21 mL/m2 vs. 122 ± 22 mL/m2, subvalvular patch: 112 ± 23 mL/m2 vs. 111 ± 23 mL/m2, non-patch: 123 ± 28 mL/m2 vs. 123 ± 23 mL/m2, P = 0.827). RVEDVI at last CMR did not differ between groups (P = 0.301). CONCLUSIONS: This study shows no progression of RV dilatation in patients after surgical repair of TOF with moderately dilated RVs and significant PR during a 3-year follow-up. RV dilatation in our patient group seems to be independent from surgical repair techniques.

More accurate quantification of pulmonary blood flow by magnetic resonance imaging than by lung perfusion scintigraphy in patients with fontan circulation.

BACKGROUND: Quantitative evaluation of pulmonary perfusion using lung perfusion scintigraphy in patients with atriopulmonary anastomosis (APA) or total cavopulmonary connection (TCPC) or partial cavopulmonary connection (PCPC) is difficult because of preferential draining of the venae cavae to one lung. Scintigraphy is the gold standard. Phase-velocity MRI (PV-MRI) is a new technique for determining pulmonary perfusion. The aim of this study was therefore to determine whether PV-MRI is more accurate than scintigraphy for quantitative evaluation of pulmonary perfusion ratios in patients with APA, TCPC, or PCPC. METHODS AND RESULTS: We studied 15 patients with APA, TCPC, or PCPC (16+/-7 years old, 4 female). Twelve patients (15+/-8 years old, 3 female) with a single pulmonary blood source supplied by a subpulmonary ventricle, ensuring complete mixing of the radioactive tracer before entering the pulmonary circulation, served as controls. Pulmonary scintigraphy and PV-MRI were performed in all patients. Bland-Altman analysis showed a clinically unacceptable difference of 7.1% right pulmonary blood flow (27.2% upper and -13.0% lower limit of agreement) between the two methods in the study group. The two methods agreed excellently in the control group (difference, 1.6%; 4.0% upper and -7.2% lower limit of agreement), showing that the bad agreement in the study group was caused by the problems encountered using pulmonary scintigraphy in patients with APA, TCPC, or PCPC. CONCLUSIONS: Because of preferential caval flow into either lung, PV-MRI is more accurate for evaluating pulmonary perfusion ratios than lung perfusion scintigraphy in patients with Fontan-like circulation.

Long-term myocardial scarring after operation for anomalous left coronary artery from the pulmonary artery.

BACKGROUND: Anomalous left coronary artery from the pulmonary artery (ALCAPA) is a very rare disease. Accordingly, the incidence and distribution of myocardial scarring in long-term follow-up of patients after successful surgery of ALCAPA is unknown. Therefore, the aim of this study was to describe the distribution of left ventricular (LV) myocardial scarring by late gadolinium enhancement magnetic resonance in these patients. METHODS: Fourteen consecutive patients over 12 years of age with ALCAPA without any further cardiac abnormalities, and after corrective surgery at our center, participated prospectively in this study. All patients underwent cardiac magnetic resonance including LV function analysis and late gadolinium enhancement magnetic resonance. Of these 14 patients, 12 patients also underwent cardiopulmonary exercise testing. RESULTS: Four patients had no evidence of myocardial scarring. The median extent of the myocardial scar of all patients by late gadolinium enhancement magnetic resonance, expressed as a percentage of the total LV myocardial volume, was only 2% (range, 0% to 11%). Median LV ejection fraction was 0.55 (range, 0.31 to 0.73). Median LV end-diastolic volume indexed to body surface area was 84 mL/m(2) (39 to 120 mL/m(2)). Median peak oxygen uptake during cardiopulmonary exercise was 24 mL · kg(-1) · minute(-1) (range, 19 to 51 mL/kg/minute). CONCLUSIONS: We conclude that despite often severely compromised LV function and evidence of scarring before corrective surgery of patients with ALCAPA, in long-term follow-up scar tissue is relatively scarce.

Patients after atrial switch operation for transposition of the great arteries can not increase stroke volume under dobutamine stress as opposed to patients with congenitally corrected transposition.

BACKGROUND: Patients after atrial switch operation for transposition of the great arteries have limited exercise performance. Rigid atrial baffles may cause a relative preload reduction. Previous studies have had suboptimal control groups, which ideally should consist of patients with congenitally corrected transposition of the great arteries (ccTGA) without previous heart surgery, having a systemic right ventricle, but lacking rigid atrial baffles. Therefore the aim of this study was to test the impact of atrial baffles by comparing 12 atrial switch patients with 11 ccTGA patients. METHODS AND RESULTS: Systemic right ventricular stroke volume (SV), heart rate, cardiac index, and other parameters were assessed during rest and dobutamine stress magnetic resonance imaging. The most important difference between the groups was that the atrial switch patients could not increase SV during stress, whereas ccTGA patients increased it significantly. There was no difference between groups in the rise of the cardiac index. Heart rate increased significantly more in atrial switch patients than in ccTGA patients. CONCLUSIONS: The results support the hypothesis that atrial baffles restrict a rise in SV under dobutamine stress in patients after atrial switch operation for transposition of the great arteries.