Fontan procedure: imaging of normal post-surgical anatomy and the spectrum of cardiac and extracardiac complications.

Univentricular congenital heart diseases include a range of entities that result in a functionally single ventricular chamber. Although the only curative therapy is cardiac transplantation, there are several palliative surgical techniques that prevent ventricular volume overload, diverting part or all the systemic venous circulation into the pulmonary arteries. The modern Fontan procedure, which consists of anastomosing both the superior (SVC) and inferior vena cava (IVC) to the right pulmonary artery (RPA), is nowadays the last step before transplantation. The importance of imaging in these entities lies not only in the understanding of the new circuit established after surgical correction, but also in the early detection of the wide spectrum of cardiac and extracardiac complications that can occur due to the new physiological condition. Due to the increased survival of these patients, long-term complications are becoming more common. The main cardiac complications are atrial enlargement, ventricular dysfunction, and stenosis or thrombosis of the conduit. Pulmonary artery stenosis, pulmonary arteriovenous fistulae (PAVF), systemic-pulmonary veno venous shunts (VVS), hepatic congestion, cardiac cirrhosis, and protein-losing enteropathy are potential extracardiac complications.

Multislice CT in graft vascular disease. A pilot study.

INTRODUCTION: Graft vessel disease (GVD) is one of the main long-term complications in heart transplant (HT) patients. At present, the diagnosis of this complication requires invasive procedures. Multislice CT is an emerging technique that allows visualization of the coronary anatomy, including the vascular lumen and wall thickness. Our objective was to establish the value of 16-detector multislice CT in the detection of GVD, compared with angiography and intravascular ultrasound (IVUS). PATIENTS AND METHODS: We studied 32 HT patients, who had a mean follow-up of 2016 days. CT was performed 24 hours prior to angiography, associated with IVUS if the latter proved normal. Comparisons were subsequently made using contingency tables to establish the sensitivity, specificity, and predictive values of the CT. RESULTS: Angiography was not performed on two patients, and eight were excluded from CT assessment due to serum creatinine values >1.5 mg/dL. Comparison of the CT findings with the invasive techniques yielded a sensitivity of 50%, a specificity of 81%, a negative predictive value of 81%, a positive predictive value of 50%, and a precision of 72%. CONCLUSIONS: Our results suggested good performance of the technique in screening for GVD because a high negative predictive value was recorded. We plan to increase the number of patients and use the 64-detector CT system to ensure greater time and spatial resolution.

Utility of cardiac magnetic resonance imaging for the diagnosis of heart transplant rejection.

OBJECTIVES: To assess the value of the use of cardiac MRI to detect rejection (necrosis) and its ability to discriminate it from other pathologic alterations (edema and fibrosis). MATERIALS AND METHODS: A prospective and consecutive study was designed in which cardiac MRI was performed at the same time as the scheduled endomyocardial biopsy. The study period was from 31-10-01 to 01-05-02. Ten patients with claustrophobia were excluded. Sixty-four examinations were performed in the remaining 40 patients. MRI assessment was blinded to the biopsy result. The 17 biopsies performed were insufficient (too small sample). Rejection was defined as the presence of at least 1 focus of myocyte necrosis. Technique. A high-field (1.5 T) GE CV/i magnetic resonance imaging system was used to obtain pre- and postcontrast white and black blood anatomic sequences (breathhold fast spin-echo T1-weighted images), as well as myocardial cine, perfusion and viability sequences. Variables analyzed. Ejection fraction, ventricular volumes, pericardial effusion, hypertrophy, absolute and relative myocardial intensity and uptake. Statistics. Variables were normally distributed. Student's t test was used for quantitative variables and the chi2 test for proportions. RESULTS: Mean age, 51+/-13 years. Women 5, men 35. Time since HT, 13 to 3725 days. No significant differences were found between rejection and ventricular volumes or the presence of effusion and hypertrophy. Visual estimation of myocardial perfusion and viability sequences did not detect any significant changes. Uptake showed a clear trend to increase in patients with necrosis: 34+/-21 versus 23+/-17 for relative uptake, P<.05. There were also differences in uptake when fibrosis was present: 68+/-47 versus 102+/-48 in the group without fibrosis, P <.05; but not in the presence of edema: 93+/-55 versus 94 +/- 45 for absolute uptake. CONCLUSIONS: (1) Cardiac MRI is a promising technique for diagnosis of rejection. (2) Patients with myocyte necrosis show a clear trend toward increased myocardial uptake. (3) Interstitial fibrosis is associated with decreased levels of uptake.