Magnetic resonance imaging: evaluation of palliative systemic-pulmonary artery shunts.

Abstract

Eleven patients with a total of 17 palliative systemic-pulmonary artery shunts underwent evaluation by electrocardiogram-gated magnetic resonance imaging (GMRI). GMRI CONGENITAL heart defects characterized by cyanosis and decreased pulmonary blood flow are often palliated by creation of systemic-pulmonary artery shunts. All of the operations that have been devised increase pulmonary blood flow and differ primarily in terms of which specific vessels are anastomosed. The evaluation of patients who have previously undergone palliative shunt procedures frequently includes imaging of the shunt and pulmonary arterial anatomy. This generally requires invasive angiographic studies, either during cardiac catheterization or, more recently, with digital subtraction techniques.Noninvasive imaging of systemic-pulmonary artery shunts has been unsatisfactory. Ultrasonography is limited by the poor echographic accessibility of these structures, which are extracardiac and enveloped by lung tissue. We have previously reported our experience with electrocardiogram-gated magnetic resonance imaging (GMRI) in patients with congenital heart defects.1 2 Included in our early work were two patients in whom palliative systemic-pulmonary artery From Patients and methodsEleven patients with cyanotic congenital heart disease in whom 17 palliative systemic-pulmonary artery shunts were present underwent evaluation by GMRI. Five patients had pulmonic atresia: two with intact ventricular septum, two with large ventricular septal defects, and one in association with a univentricular heart. Three patients had tricuspid atresia and the remaining three had atrioventricular septal defects, with severe pulmonic stenosis in two and a tight pulmonary arterial band in the other. Six patients had two shunts. There were nine BlalockTaussig shunts, six Glenn shunts, one Waterston shunt, and one Potts shunt. Patients ranged in age from 1 to 21 years (mean 13). Only one patient was under 2 years of age. This patient was sedated with 2 mg/kg meperidine. 1 mg/kg promethazine, and 1 mg/kg chlorpromazine. Informed consent was obtained in all cases from the patient or the patient's guardian.Images were obtained with a superconducting magnet operating at 0.3 T (Technicare; Solon, OH). At this field strength the resonant frequency for protons is 12.85 MHz. Infants were placed within a smaller 29 cm head-coil radio antenna inserted into the 100 cm magnet bore to improve signal-to-noise ratio. A 90 degree saturation-recovery pulse was followed in 15 msec by a 180 degree pulse, resulting in a peak ''read-echo 30 msec after the 90 degree pulse. Image acquisition was gated to systole by initiating the 90 degree saturation-recovery pulse at a prede-CIRCULATION

Clinical indications for cardiovascular magnetic resonance (CMR): Consensus Panel report?

“…[48][49][50][51] Patients with extracardiac ventriculopulmonary shunts often experience graft degeneration and echocardiographic imaging is difficult due to the retrosternal position of the graft. CMR provides accurate anatomic and functional information and is the technique of choice for following these patients.…”

Evaluation of Blalock-Taussig shunts in newborns: value of oblique MRI planes

“…Other authors have suggested that MR imaging may be helpful in the evaluation of palliative systemic-pulmonary shunts in older children. Jacobstein et al reported successful imaging in 11 of 17 angiographicaUy controlled shunts [1]. Didier et al mentioned that MR imaging accurately assessed 4 Blalock-Taussig shunts included in a series of 15 postoperative congenital heart patients [2].…”

“…ECG-gated MRI can be used in postoperative controls of a variety of surgical procedures [1,7]. Several of these studies [1,4] have included postoperative evaluation of palliative systemic shunts.…”

“…Several of these studies [1,4] have included postoperative evaluation of palliative systemic shunts. These studies have shown the limitations of MR imaging visualizing the shunts entirely on one single projection with conventionnal coronal imaging planes [1].…”

Noninvasive diagnosis of congenital left coronary artery to right ventricle fistula by nuclear magnetic resonance imaging

“…This technique, in addition to describing chamber enlargement and function, has the advantage of characterizing flow patterns in the CAVF and in the chamber of fistulous communication . Previous studies have demonstrated the utility of cardiac gated NMR to image many cardiac malformations including septal defects, great vessel malpositions, coarctation of the aorta, cardiac tumors, and surgically created aorticopulmonary shunts [1][2][3] . In addition, the proximal coronary artery has been visualized by the NMR imaging technique [7] .…”