Radiation-free CMR diagnostic heart catheterization in children

Abstract

Background: Children with heart disease may require repeated X-Ray cardiac catheterization procedures, are more radiosensitive, and more likely to survive to experience oncologic risks of medical radiation. Cardiovascular magnetic resonance (CMR) is radiation-free and offers information about structure, function, and perfusion but not hemodynamics. We intend to perform complete radiation-free diagnostic right heart catheterization entirely using CMR fluoroscopy guidance in an unselected cohort of pediatric patients; we report the feasibility and safety.

Methods: We performed 50 CMR fluoroscopy guided comprehensive transfemoral right heart catheterizations in 39 pediatric (12.7 ± 4.7 years) subjects referred for clinically indicated cardiac catheterization. CMR guided catheterizations were assessed by completion (success/failure), procedure time, and safety events (catheterization, anesthesia). Pre and post CMR body temperature was recorded. Concurrent invasive hemodynamic and diagnostic CMR data were collected.

Results: During a twenty-two month period (3/2015 - 12/2016), enrolled subjects had the following clinical indications: post-heart transplant 33%, shunt 28%, pulmonary hypertension 18%, cardiomyopathy 15%, valvular heart disease 3%, and other 3%. Radiation-free CMR guided right heart catheterization attempts were all successful using passive catheters. In two subjects with septal defects, right and left heart catheterization were performed. There were no complications. One subject had six such procedures. Most subjects (51%) had undergone multiple (5.5 ± 5) previous X-Ray cardiac catheterizations. Retained thoracic surgical or transcatheter implants (36%) did not preclude successful CMR fluoroscopy heart catheterization. During the procedure, two subjects were receiving vasopressor infusions at baseline because of poor cardiac function, and in ten procedures, multiple hemodynamic conditions were tested.

Conclusions: Comprehensive CMR fluoroscopy guided right heart catheterization was feasible and safe in this small cohort of pediatric subjects. This includes subjects with previous metallic implants, those requiring continuous vasopressor medication infusions, and those requiring pharmacologic provocation. Children requiring multiple, serial X-Ray cardiac catheterizations may benefit most from radiation sparing. This is a step toward wholly CMR guided diagnostic (right and left heart) cardiac catheterization and future CMR guided cardiac intervention.

Trial registration: ClinicalTrials.gov NCT02739087 registered February 17, 2016.

Keywords: Catheterization; Interventional Cardiovascular MRI; MRI fluoroscopy; Magnetic Resonance Imaging; Real-time MRI.

Fig. 1

Patient enrollment

Fig. 2

ICMR suite. CMR heart catheterization procedures were performed in an interventional CMR suite (Panel a) consisting of adjoining CMR room and biplane X-Ray fluoroscopy suite. The interventional cardiac MRI room is outfitted for invasive cardiac catheterization (Panels b, c). The patient and CMR scanner have sterile drapes. Operators observe sterile technique and wear noise-cancelling communication headsets. Commercially available passive catheters are connected to conventional pressure transducers that interface (panel b black box) with the commercial hemodynamic recording system. The room is equipped with commercial projectors that are shielded for CMR operation. Rear projected images show the commercial hemodynamic recording system (panel c, upper left), and real-time CMR console (panel c, lower left). Commercial hemodynamic monitor (panel c, upper right) and CMR host (panel c, lower right) are also shown

Fig. 3

CMR right heart catheterization. Panels (a, b, and c) show real time CMR catheter navigation to superior vena cava (SVC), right ventricle (RV), and right pulmonary artery (RPA) respectively. Panels (d, e, and f) show the same respective imaging planes after flow-sensitive saturation preparation pulse to null blood pool. Gadolinium filled balloon (white arrow) is easily and often better (best represented in panel b versus panel e) visualized during this real-time black blood imaging

Fig. 4

CMR cardiac catheterization in patient with pulmonary artery stent imaging artifact. Panel (a) shows imaging artifact (circled) from previously placed pulmonary artery stents; CMR right heart catheterization was successful. Panel (b) shows oblique axial imaging plane showing branch pulmonary arteries (thick white arrow = stent imaging artifact). Panel (e) and (g) show oblique coronal imaging planes for right and left pulmonary artery respectively. Panels c (RPA = right pulmonary artery), d (LPA = left pulmonary artery), f (RPA), h (LPA) show the same respective imaging planes after flow-sensitive saturation preparation pulse to null blood pool. Gadolinium filled balloon is easily visualized during this real-time black blood imaging

Fig. 5

Left heart CMR catheterization in patients with atrial septal defect and complete atrioventricular canal defect. Real-time CMR guided left heart catheterization in patients with atrial septal defect (panels a–d) and complete atrioventricular canal defect (panels e–h) are shown. Each two panel sequence (i.e., Panels a/b, etc.) are in the same imaging plane with standard real-time steady state free precession and after flow-sensitive saturation preparation pulse to null blood pool. Panel (b) shows the gadolinium filled balloon navigated from right atrium across the atrial septal defect to the right upper pulmonary vein (RUPV). Panel (d) shows the balloon navigated to the left ventricle (LV). Panel (f) shows the balloon in the left atrium (LA). Panel (h) shows the balloon after navigation to the left ventricle