Cardiovascular magnetic resonance imaging for intensive care infants: safe and effective?

BACKGROUND: Cardiac magnetic resonance imaging (MRI) is an important diagnostic tool for congenital heart disease (CHD), as reflected by class 1 recommendations for the use of cardiac MRI by various consensus panels. However, little is known about the safety and clinical utility of cardiac MRI for these critically ill infants with CHD, whose further management cannot be directed by echocardiography. This study aimed to assess the safety, the potential hemodynamic side effects, and the clinical benefits of cardiac MRI for infants with complex CHD during their intensive care unit stay. METHODS: Infants referred from the pediatric cardiac intensive care unit (PCICU) to the authors' cardiac MRI program in the past 2 years were retrospectively analyzed using the electronic chart system available at their institution. Data collected included age, diagnosis, inotropic support, urine output, diuretic medication, body temperature and lactate levels, length of MRI examination, adverse effects during and after the procedure, clinical implications of MRI, length of stay in the PCICU, and mean blood pressure and heart rate before, during, and after MRI. RESULTS: Among 592 patients in the past 2 years, 20 (3.4%) were referred for MRI testing during their stay in the PCICU. The mean age of the infants was 4.8+/-3.2 months. Four of the patients were neonates, and eight were postoperative patients. Intracardiac malformations were present in 16 of the infants, vascular rings causing tracheal stenosis in 3 patients, and cardiomyopathy in 1 patient. The mean stay in the PCICU was 28+/-43 days. Eight of the infants were ventilated, with a mean fraction of inspired oxygen (FiO2) of 0.30+/-0.15. Four were receiving inotropic support. All the nonventilated children were intubated for the MRI and extubated in the MRI laboratory. The mean duration of the MRI (door-to-door time) was 110+/-27 min. All except one patient were hemodynamically stable, and no increase in catecholamine support was necessary during or after the scans. A 10-month-old girl receiving inotropic support needed a single dose of epinephrine due to a short episode of bradycardia after a breathhold for a contrast agent MRI angiography. Mean body core temperature at arrival to the PCICU was 36.8+/-0.7 degrees C. The mean serum lactate level after the MRI was 1.2+/-0.4 mmol/l. The mean blood pressure and heart rate before, during, and after MRI were unchanged. The mean diuresis on examination day was insignificantly lower (2.4%) than the day before with unchanged medication (5.09+/-1.58 vs 5.53+/-1.77 ml/kg/h). For 14 (70%) of the 20 patients, surgical or catheter interventional procedures were initiated based on novel MRI information. CONCLUSION: Cardiac MRI can be performed safely with low risk and limited hemodynamic changes for infants during their stay in the PCICU. Cardiac MRI provides key information for invasive management decisions in this subset of patients.

Anterograde stent implantation for treatment of recurrent coarctation after Norwood operation.

Although balloon angioplasty (BA) has become the standard therapy for recurrent aortic arch obstruction, pressure gradient relief is often not complete, with a high incidence of restenosis after BA. We report our experience with anterograde stent implantation for treatment of recurrent arch obstruction in patients with hypoplastic left heart syndrome after Norwood operation. Between March 2003 and January 2006, seven patients with the Norwood procedure required BA. The average weight was 6.3 kg (range, 4.4-9.8 kg). Four patients had undergone prior BA. For the purpose of relieving aortic arch obstruction, we used five Palmaz Genesis (PG) XD stents, and for palliative purposes we used one PG 124P stent and one Jostent, 6-12 mm. The average time after Norwood stage I was 177 days (range, 56-365 days). In six of seven patients the procedure was performed antegradely from the femoral vein. In all patients the procedure was effective. The peak systolic gradient fell from 29 mm Hg (range, 5-70 mm Hg) to 3 mm Hg (range, 0-10 mm Hg). There were no complications. No aneurysm, stent dislocation, or severe bleeding was observed. In two of seven patients three growth-related redilatations were performed. We conclude that implantation of stents at the site of recurrent coarctation after Norwood operation shows excellent gradient relief. To reduce the risk of vascular complications due to arterial access in this small group of patients, the procedure can be done safely anterogradely.

Implantation of stents for treatment of recurrent and native coarctation in children weighing less than 20 kilograms.

We report our experience with implantation of stents for treatment of recurrent and native aortic coarctation in children weighing less than 20 kilograms. We treated 9 such patients between March, 2003, and January, 2006. In 2 patients, the coarctation had not previously been treated, while in 7 it had recurred after surgery. The patients had a median weight of 14 kilograms, with a range from 5.5 to 19 kilograms. Balloon dilation was needed in 1 patient before the stent was implanted. We used Palmaz Genesis XD stents in 7 patients, these having lengths from 19 to 29 millimetres, 1 Palmaz Genesis 124P stent, and 1 peripheral JoStent with a diameter of 6 to 12 millimetres. Implantation was effective in all patients. Immediately after implantation, the mean peak systolic gradient decreased from 30 millimetres of mercury, the range having been 15 to 50 mm, to 3 millimetres of mercury, with the final range from zero to 10 mm. There were no complications, with no observations of aneurysms, dissections, or dislocated stents. In 1 patient, the peripheral pulse was weak secondary to arterial access, but treatment with Heparin led to complete resolution. It was necessary to re-dilate the stent in another patient, while 2 others are scheduled for redilation because of growth-related restenosis. Our findings suggest that implantation of stents can produce excellent relief of the gradient produced by recurrent or native coarctation. The process is safe and effective in patients weighing less than 20 kilograms.

Resolution of protein-losing enteropathy after radiofrequency perforation and subsequent stent implantation for relief of complete occlusion of a redirected left superior vena cava.

The application of radiofrequency (RF) technologies in the treatment of congenital heart defects has provided a safe and effective alternative to conventional therapies in the restoration of vascular patency for a variety of arterial and venous occlusions. This report concerns an 8-year old girl that developed protein-losing enteropathy and elevated central venous pressure after occlusion of a surgically redirected anomalous draining left superior vena cava (SVC). Cardiac catheterization revealed complete obstruction of the anastomosis of the SVC into the coronary sinus. Transcatheter recanalization by RF perforation and subsequent stent implantation led to the restoration of upper venous blood flow and the resolution of her symptoms.