Cardiac Magnetic Resonance Stress-perfusion Study in Patinets with Fontan Circulation

Att Överleva Och Leva Som Vuxen Med Enkammarhjärta I Sverige

Univentricular heart (UVH) is a severe congenital heart disease. Accurate advanced non-invasive diagnostic methods is limited. Cardiovascular magnetic resonance (CMR) imaging has evolved as a particularly useful tool for the study of patients with adult congenital heart disease (ACHD) considering its ability to determine detailed anatomy and detect early cardiac dysfunction without the need for radiation exposure. Most of contemporary treatment recommendations are based on consensus opinions/documents and small studies from local, or national registries. Improved knowledge is needed in all these areas to facilitate clinical decisions regarding treatment, monitoring and follow-up.

This study seeks to answer if early detection of deterioration in cardiac function, venous pressure and microvascular dysfunction can identify patients before the symptoms progress and thus help to initiate early treatment. The hypothesis is that quantitative myocardial stress-perfusion maps improves the pathophysiological insight in patients with UVH.

The overall goal with this research proposal is to implement combined advanced CMR imaging for a comprehensive non-invasive mapping of functional cardiovascular behavior in patients with complex UVH disease. The outcome of this research may benefit this young adult patient population due to early detection of cardiac disease, less hospitalizations because of heart failure, and eventually decrease morbidity and mortality.

CMR is performed supine with a Magnetom Aera® 1.5 Tesla (T) scanner (Siemens Healthcare, Erlangen, Germany), with a phased-array 18-channel body matrix coil and a spine matrix coil. A venous blood sample is drawn to determine hematocrit and blood creatinine prior to imaging. Full coverage retrospective electrocardiographic (ECG)-gated balanced steady state free precession (bSSFP) cine imaging is acquired in standard three long-axis and short-axis slices. Typical imaging parameters are flip angle 68°, pixel size 1.4 × 1.9 mm2, slice thickness 8.0 mm, echo time (TE)/repetition time (TR) 1.19/37.05 ms, matrix size 256 × 144 and field of view (FOV) 360 × 270 mm2.

Using first-pass perfusion imaging, quantitative perfusion maps (ml/min/g) are acquired in one short-axis and one long-axis slice (mid-ventricular, 2-chamber) during administration of an intravenous contrast-agent bolus (0.05 mmol/kg, gadobutrol, Gadovist, Bayer AB, Solna, Sweden), during adenosine infusion (110 µg/kg/min or increased according to clinical routine to 140 µg/kg/min in the absence of adequate response to adenosine (Adenosine, Life Medical AB, Stockholm) and in subsequent rest. Adenosine response is assessed clinically based on symptoms and heart rate response. Adenosine and contrast agent are administered in two different cannulas. Subjects abstained from caffeine for 24 hours prior to CMR examination. A distributed tissue exchange model is used to compute the perfusion maps and the Gadgetron (reconstruction computer) inline perfusion mapping software is used to generate the perfusion maps.Typical imaging parameters were bSSFP single shot readout, flip angel 50°, slice thickness 8.0 mm, TE/TR 1.04/2.5 ms, bandwidth 1085 Hz/pixel, FOV 360 × 270 mm2 and saturation delay/trigger delay (TD) 95/40 ms.

Inclusion Criteria:

• Patients who had undergone total cavo-pulmonary connection (TCPC) surgery resulting in Fontan circulation.
• NYHA (New York Heart Assosiation) class I-II.
• Understanding the study information (signed informed consent).
• >18 years old.

Exclusion Criteria:

• Device therapy (pacemaker, ICD).
• Failing Fontan (NYHA III-IV).
• Kidney failure (GFR<30ml/h).
• Arrythmia (atrial fibrillation).
• Pregnancy.