Noninvasive assessment of repaired tetralogy of Fallot by magnetic resonance imaging and dynamic radionuclide studies

Trends in pediatric cardiovascular magnetic resonance imaging

Cardiac magnetic resonance (CMR) imaging has significantly evolved over the last decade, becoming an integral part of the contemporary assessment of both congenital and acquired pediatric heart disease. Recent trends show that there is a growing interest in clinical applications and research in this field. An attempt to discuss the evolving technologies, techniques, and applications of CMR in pediatrics is not complete without understanding the current strengths of the modality. CMR complements readily available echocardiography, in many cases information from CMR can remove the need for invasive angiographic catheterization, and in other cases can be used to augment cardiac catheterisation.

4D cardiovascular magnetic resonance velocity mapping of alterations of right heart flow patterns and main pulmonary artery hemodynamics in tetralogy of Fallot

BACKGROUND

To assess changes in right heart flow and pulmonary artery hemodynamics in patients with repaired Tetralogy of Fallot (rTOF) we used whole heart, four dimensional (4D) velocity mapping (VM) cardiovascular magnetic resonance (CMR).

METHODS

CMR studies were performed in 11 subjects with rTOF (5M/6F; 20.1 ± 12.4 years) and 10 normal volunteers (6M/4F; 34.2 ± 13.4 years) on clinical 1.5T and 3.0T MR scanners. 4D VM-CMR was performed using PC VIPR (Phase Contrast Vastly undersampled Isotropic Projection Reconstruction). Interactive streamline and particle trace visualizations of the superior and inferior vena cava (IVC and SVC, respectively), right atrium (RA), right ventricle (RV), and pulmonary artery (PA) were generated and reviewed by three experienced readers. Main PA net flow, retrograde flow, peak flow, time-to-peak flow, peak acceleration, resistance index and mean wall shear stress were quantified. Differences in flow patterns between the two groups were tested using Fisher's exact test. Differences in quantitative parameters were analyzed with the Kruskal-Wallis rank sum test.

RESULTS

4D VM-CMR was successfully performed in all volunteers and subjects with TOF. Right heart flow patterns in rTOF subjects were characterized by (a) greater SVC/IVC flow during diastole than systole, (b) increased vortical flow patterns in the RA and in the RV during diastole, and (c) increased helical or vortical flow features in the PA's. Differences in main PA retrograde flow, resistance index, peak flow, time-to-peak flow, peak acceleration and mean wall shear stress were statistically significant.

CONCLUSIONS

Whole heart 4D VM-CMR with PC VIPR enables detection of both normal and abnormal right heart flow patterns, which may allow for comprehensive studies to evaluate interdependencies of post-surgically altered geometries and hemodynamics.

The role of cardiovascular magnetic resonance in pediatric congenital heart disease

Cardiovascular magnetic resonance (CMR) has expanded its role in the diagnosis and management of congenital heart disease (CHD) and acquired heart disease in pediatric patients. Ongoing technological advancements in both data acquisition and data presentation have enabled CMR to be integrated into clinical practice with increasing understanding of the advantages and limitations of the technique by pediatric cardiologists and congenital heart surgeons. Importantly, the combination of exquisite 3D anatomy with physiological data enables CMR to provide a unique perspective for the management of many patients with CHD. Imaging small children with CHD is challenging, and in this article we will review the technical adjustments, imaging protocols and application of CMR in the pediatric population.

Tetralogy of Fallot in teenagers and adults: surgical experience and follow-up

OBJECTIVE

The aim of this study was to review short- and long-term outcomes following total correction in patients with tetralogy of Fallot that presented during adulthood.

METHODS

It was a retrospective analysis of 284 patients (aged 14-50 years, mean 19.4 +/- 2.5 years) with tetralogy of Fallot who underwent total correction at our institution between January 1991 and December 2001. Thirty patients were subjected to postoperative first-pass radionuclide angiocardiography scans. A Hindi version of the standard World Health Organization quality of life proforma was mailed to 120 patients operated on during the first half of the study period.

RESULTS

Altogether, 45 (15.8%) patients had palliative shunts, and 32 (11%) had preoperative coil embolization. The transatrial/transpulmonary artery approach was used in 62 (22%) patients, the transventricular approach in 86 (30%) patients, and a combined approach in 136 (48%) patients. A transannular pericardial patch was used in 200 (70%) patients. A total of 61 (21%) patients had nonfatal complications. There were 28 hospital deaths. Follow-up ranged from 1 month to 10 years (mean 4.6 +/- 2.3 years). There were 7 (2.5%) late deaths and 6 (2.1%) reoperations. Altogether, 94% of patients were in New Yk Heart Association (NYHA) class I. Radionuclide angiocardiography showed normal right ventricular and left ventricular function in 18 (60%) and 22 (73%) patients, respectively. All of the 66 respondents perceived an improved quality of life. The actuarial survival and freedom from reoperation at 10 years were 82.88% +/- 3.80% and 92.82% +/- 3.40%, respectively.

CONCLUSION

Total correction in this subset of patients offers the best option for long-term symptom-free survival.

Assessment of blood flow and valvular heart disease using phase-contrast cardiovascular magnetic resonance

Measurement of blood flow is important for assessing the severity of disease processes involving the cardiovascular system. Phase-contrast cardiovascular magnetic resonance (PC-CMR) can be used to measure blood flow noninvasively without ionizing radiation or limitations imposed by body habitus. This review describes the performance of PC-CMR and its clinical utility in assessing patients with cardiovascular or valvular heart disease.

Cardiac MRI Is an Important Complementary Tool to Doppler Echocardiography in the Management of Patients with Pulmonary Regurgitation

Cardiac MRI (CMR) is a noninvasive diagnostic tool with comprehensive capabilities similar to that of two-dimensional echocardiography with Doppler. In addition to the ability to evaluate the etiology and severity of pulmonary valve regurgitation (PR), CMR is well designed to serially monitor the impact of the PR on the right ventricle (RV). Importantly, RV dilation and dysfunction is a critical determinate to time surgical intervention. CMR gives the silent RV, suffering from PR, a voice.