X-ray fused with MRI guidance of pre-selected transcatheter congenital heart disease interventions.

OBJECTIVES: To determine whether X-ray fused with MRI (XFM) is beneficial for select transcatheter congenital heart disease interventions. BACKGROUND: Complex transcatheter interventions often require three-dimensional (3D) soft tissue imaging guidance. Fusion imaging with live X-ray fluoroscopy can potentially improve and simplify procedures. METHODS: Patients referred for select congenital heart disease interventions were prospectively enrolled. Cardiac MRI data was overlaid on live fluoroscopy for procedural guidance. Likert scale operator assessments of value were recorded. Fluoroscopy time, radiation exposure, contrast dose, and procedure time were compared to matched cases from our institutional experience. RESULTS: Forty-six patients were enrolled. Pre-catheterization, same day cardiac MRI findings indicated intervention should be deferred in nine patients. XFM-guided cardiac catheterization was performed in 37 (median age 8.7 years [0.5-63 years]; median weight 28 kg [5.6-110 kg]) with the following prespecified indications: pulmonary artery (PA) stenosis (n = 13), aortic coarctation (n = 12), conduit stenosis/insufficiency (n = 9), and ventricular septal defect (n = 3). Diagnostic catheterization showed intervention was not indicated in 12 additional cases. XFM-guided intervention was performed in the remaining 25. Fluoroscopy time was shorter for XFM-guided intervention cases compared to matched controls. There was no significant difference in radiation dose area product, contrast volume, or procedure time. Operator Likert scores indicated XFM provided useful soft tissue guidance in all cases and was never misleading. CONCLUSIONS: XFM provides operators with meaningful three-dimensional soft tissue data and reduces fluoroscopy time in select congenital heart disease interventions.

Right heart catheterization using metallic guidewires and low SAR cardiovascular magnetic resonance fluoroscopy at 1.5 Tesla: first in human experience.

BACKGROUND: Cardiovascular magnetic resonance (CMR) fluoroscopy allows for simultaneous measurement of cardiac function, flow and chamber pressure during diagnostic heart catheterization. To date, commercial metallic guidewires were considered contraindicated during CMR fluoroscopy due to concerns over radiofrequency (RF)-induced heating. The inability to use metallic guidewires hampers catheter navigation in patients with challenging anatomy. Here we use low specific absorption rate (SAR) imaging from gradient echo spiral acquisitions and a commercial nitinol guidewire for CMR fluoroscopy right heart catheterization in patients. METHODS: The low-SAR imaging protocol used a reduced flip angle gradient echo acquisition (10° vs 45°) and a longer repetition time (TR) spiral readout (10 ms vs 2.98 ms). Temperature was measured in vitro in the ASTM 2182 gel phantom and post-mortem animal experiments to ensure freedom from heating with the selected guidewire (150 cm × 0.035″ angled-tip nitinol Terumo Glidewire). Seven patients underwent CMR fluoroscopy catheterization. Time to enter each chamber (superior vena cava, main pulmonary artery, and each branch pulmonary artery) was recorded and device visibility and confidence in catheter and guidewire position were scored on a Likert-type scale. RESULTS: Negligible heating (< 0.07°C) was observed under all in vitro conditions using this guidewire and imaging approach. In patients, chamber entry was successful in 100% of attempts with a guidewire compared to 94% without a guidewire, with failures to reach the branch pulmonary arteries. Time-to-enter each chamber was similar (p=NS) for  the two approaches. The guidewire imparted useful catheter shaft conspicuity and enabled interactive modification of catheter shaft stiffness, however, the guidewire tip visibility was poor. CONCLUSIONS: Under specific conditions, trained operators can apply low-SAR imaging and using a specific fully-insulated metallic nitinol guidewire (150 cm × 0.035" Terumo Glidewire) to augment clinical CMR fluoroscopy right heart catheterization. TRIAL REGISTRATION: Clinicaltrials.gov NCT03152773 , registered May 15, 2017.

Increasing propensity to pursue operative closure of atrial septal defects following changes in the instructions for use of the Amplatzer Septal Occluder device: An observational study using data from the Pediatric Health Information Systems database.

Concern for device erosion following transcatheter treatment of atrial septal defects (TC-ASD) led in 2012 to a United States Food and Drug Administration panel review and changes in the instructions for use of the Amplatzer Septal Occluder (ASO) device. No studies have assessed the effect of these changes on real-world practice. To this end a multicenter observational study was performed to evaluate trends in the treatment of ASD. METHODS: A retrospective observational study was performed using data from the Pediatric Health Information Systems database of all patients with isolated ASD undergoing either TC-ASD or operative ASD closure (O-ASD) from January 1, 2007, to September 30, 2015, hypothesizing that the propensity to pursue O-ASD increased beginning in 2013. RESULTS: A total of 6,392 cases from 39 centers underwent ASD closure (82% TC-ASD). Adjusting for patient factors, between 2007 and 2012, the probability of pursuing O-ASD decreased (odds ratio [OR] 0.95 per year, P = .03). This trend reversed beginning in 2013, with the probability of O-ASD increasing annually (OR 1.21, P = .006). There was significant between-hospital variation in the choice between TC-ASD and O-ASD (median OR 2.79, P < .0001). The age of patients undergoing ASD closure (regardless of method) decreased over the study period (P = .04). Cost of O-ASD increased over the study period, whereas cost of TC-ASD and length of stay for both O-ASD and TC-ASD was unchanged. CONCLUSIONS: Although TC-ASD remains the predominant method of ASD closure, the propensity to pursue O-ASD has increased significantly following changes in instructions for use for ASO. Further research is necessary to determine what effect this has on outcomes and resource utilization.

Acute Cardiac MRI Assessment of Radiofrequency Ablation Lesions for Pediatric Ventricular Arrhythmia: Feasibility and Clinical Correlation.

BACKGROUND: Arrhythmia ablation with current techniques is not universally successful. Inadequate ablation lesion formation may be responsible for some arrhythmia recurrences. Periprocedural visualization of ablation lesions may identify inadequate lesions and gaps to guide further ablation and reduce risk of arrhythmia recurrence. METHODS: This feasibility study assessed acute postprocedure ablation lesions by MRI, and correlated these findings with clinical outcomes. Ten pediatric patients who underwent ventricular tachycardia ablation were transferred immediately postablation to a 1.5T MRI scanner and late gadolinium enhancement (LGE) imaging was performed to characterize ablation lesions. Immediate and mid-term arrhythmia recurrences were assessed. RESULTS: Patient characteristics include median age 14 years (1-18 years), median weight 52 kg (11-81 kg), normal cardiac anatomy (n = 6), d-transposition of great arteries post arterial switch repair (n = 2), anomalous coronary artery origin post repair (n = 1), and cardiac rhabdomyoma (n = 1). All patients underwent radiofrequency catheter ablation of ventricular arrhythmia with acute procedural success. LGE was identified at the reported ablation site in 9/10 patients, all arrhythmia-free at median 7 months follow-up. LGE was not visible in 1 patient who had recurrence of frequent premature ventricular contractions within 2 hours, confirmed on Holter at 1 and 21 months post procedure. CONCLUSIONS: Ventricular ablation lesion visibility by MRI in the acute post procedure setting is feasible. Lesions identifiable with MRI may correlate with clinical outcomes. Acute MRI identification of gaps or inadequate lesions may provide the unique temporal opportunity for additional ablation therapy to decrease arrhythmia recurrence.

Real-time MRI guidance of cardiac interventions.

Cardiac magnetic resonance imaging (MRI) is appealing to guide complex cardiac procedures because it is ionizing radiation-free and offers flexible soft-tissue contrast. Interventional cardiac MR promises to improve existing procedures and enable new ones for complex arrhythmias, as well as congenital and structural heart disease. Guiding invasive procedures demands faster image acquisition, reconstruction and analysis, as well as intuitive intraprocedural display of imaging data. Standard cardiac MR techniques such as 3D anatomical imaging, cardiac function and flow, parameter mapping, and late-gadolinium enhancement can be used to gather valuable clinical data at various procedural stages. Rapid intraprocedural image analysis can extract and highlight critical information about interventional targets and outcomes. In some cases, real-time interactive imaging is used to provide a continuous stream of images displayed to interventionalists for dynamic device navigation. Alternatively, devices are navigated relative to a roadmap of major cardiac structures generated through fast segmentation and registration. Interventional devices can be visualized and tracked throughout a procedure with specialized imaging methods. In a clinical setting, advanced imaging must be integrated with other clinical tools and patient data. In order to perform these complex procedures, interventional cardiac MR relies on customized equipment, such as interactive imaging environments, in-room image display, audio communication, hemodynamic monitoring and recording systems, and electroanatomical mapping and ablation systems. Operating in this sophisticated environment requires coordination and planning. This review provides an overview of the imaging technology used in MRI-guided cardiac interventions. Specifically, this review outlines clinical targets, standard image acquisition and analysis tools, and the integration of these tools into clinical workflow. LEVEL OF EVIDENCE: 1 Technical Efficacy: Stage 5 J. Magn. Reson. Imaging 2017;46:935-950.

CMR fluoroscopy right heart catheterization for cardiac output and pulmonary vascular resistance: results in 102 patients.

BACKGROUND: Quantification of cardiac output and pulmonary vascular resistance (PVR) are critical components of invasive hemodynamic assessment, and can be measured concurrently with pressures using phase contrast CMR flow during real-time CMR guided cardiac catheterization. METHODS: One hundred two consecutive patients underwent CMR fluoroscopy guided right heart catheterization (RHC) with simultaneous measurement of pressure, cardiac output and pulmonary vascular resistance using CMR flow and the Fick principle for comparison. Procedural success, catheterization time and adverse events were prospectively collected. RESULTS: RHC was successfully completed in 97/102 (95.1%) patients without complication. Catheterization time was 20 ± 11 min. In patients with and without pulmonary hypertension, baseline mean pulmonary artery pressure was 39 ± 12 mmHg vs. 18 ± 4 mmHg (p < 0.001), right ventricular (RV) end diastolic volume was 104 ± 64 vs. 74 ± 24 (p = 0.02), and RV end-systolic volume was 49 ± 30 vs. 31 ± 13 (p = 0.004) respectively. 103 paired cardiac output and 99 paired PVR calculations across multiple conditions were analyzed. At baseline, the bias between cardiac output by CMR and Fick was 5.9% with limits of agreement -38.3% and 50.2% with r = 0.81 (p < 0.001). The bias between PVR by CMR and Fick was -0.02 WU.m2 with limits of agreement -2.6 and 2.5 WU.m2 with r = 0.98 (p < 0.001). Correlation coefficients were lower and limits of agreement wider during physiological provocation with inhaled 100% oxygen and 40 ppm nitric oxide. CONCLUSIONS: CMR fluoroscopy guided cardiac catheterization is safe, with acceptable procedure times and high procedural success rate. Cardiac output and PVR measurements using CMR flow correlated well with the Fick at baseline and are likely more accurate during physiological provocation with supplemental high-concentration inhaled oxygen. TRIAL REGISTRATION: Clinicaltrials.gov NCT01287026 , registered January 25, 2011.

Radiation-free CMR diagnostic heart catheterization in children.

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.

Dark blood late enhancement imaging.

BACKGROUND: Bright blood late gadolinium enhancement (LGE) imaging typically achieves excellent contrast between infarcted and normal myocardium. However, the contrast between the myocardial infarction (MI) and the blood pool is frequently suboptimal. A large fraction of infarctions caused by coronary artery disease are sub-endocardial and thus adjacent to the blood pool. It is not infrequent that sub-endocardial MIs are difficult to detect or clearly delineate. METHODS: In this present work, an inversion recovery (IR) T2 preparation was combined with single shot steady state free precession imaging and respiratory motion corrected averaging to achieve dark blood LGE images with good signal to noise ratio while maintaining the desired spatial and temporal resolution. In this manner, imaging was conducted free-breathing, which has benefits for image quality, patient comfort, and clinical workflow in both adults and children. Furthermore, by using a phase sensitive inversion recovery reconstruction the blood signal may be made darker than the myocardium (i.e., negative signal values) thereby providing contrast between the blood and both the MI and remote myocardium. In the proposed approach, a single T1-map scout was used to measure the myocardial and blood T1 using a MOdified Look-Locker Inversion recovery (MOLLI) protocol and all protocol parameters were automatically calculated from these values within the sequence thereby simplifying the user interface. RESULTS: The contrast to noise ratio (CNR) between MI and remote myocardium was measured in n = 30 subjects with subendocardial MI using both bright blood and dark blood protocols. The CNR for the dark blood protocol had a 13 % loss compared to the bright blood protocol. The CNR between the MI and blood pool was positive for all dark blood cases, and was negative in 63 % of the bright blood cases. The conspicuity of subendocardial fibrosis and MI was greatly improved by dark blood (DB) PSIR as well as the delineation of the subendocardial border. CONCLUSIONS: Free-breathing, dark blood PSIR LGE imaging was demonstrated to improve the visualization of subendocardial MI and fibrosis in cases with low contrast with adjacent blood pool. The proposed method also improves visualization of thin walled fibrous structures such as atrial walls and valves, as well as papillary muscles.

Use of Pulmonary Hypertension Medications in Patients with Tetralogy of Fallot with Pulmonary Atresia and Multiple Aortopulmonary Collaterals.

Tetralogy of Fallot (TOF) with pulmonary atresia (PA) and multiple aortopulmonary collaterals (MAPCAs) is a rare and severe form of congenital heart disease with poor prognosis. Aortopulmonary collaterals expose pulmonary arterioles to systemic pressure resulting in pulmonary hypertension (PH). To date, reports regarding the role of PH medications in this population are sparse. The objective of this study was to assess the effect of PH medications in patients with TOF, PA and MAPCAs or similar anatomy, with emphasis on symptoms, echocardiography and invasive hemodynamics. A retrospective review was performed for patients at a single tertiary care pediatric center. Twelve of 66 patients were treated with PH medications (18 %), and eight of these patients had adequate follow-up for further analysis. Median age at last follow-up was 6 years (range 1.4-21 years). Median length of therapy with PH medication was 4 years (range 0.3-17 years). PH medications included sildenafil, bosentan, ambrisentan, inhaled treprostinil and prostacyclin infusion. PH therapy was associated with improvement in symptoms in all patients and improvement in PH by hemodynamic measures in the majority of patients. All patients underwent at least one cardiac intervention by catheterization or surgery while taking PH medication. Two patients died from non-PH-related causes. The remaining six patients are alive and remain on PH medication. This review indicates that PH medications are well tolerated by this patient group and provide symptomatic improvement. Further studies are required to determine whether PH medications provide long-term survival benefit for patients with complex congenital heart disease.

Ablation of ventricular arrhythmia originating from the aortic sinus of Valsalva in an adolescent with anomalous origin of the right coronary artery.

A 16-year-old patient underwent successful ablation of ventricular arrhythmia originating from the aortic sinus of Valsalva following surgical unroofing of an anomalous right coronary artery. This case illustrates the complexity of decision making in the management of patients with anomalous coronary arteries and the importance of keeping an open mind when determining ventricular arrhythmia aetiology and origin.

The Role of 3-D Heart Models in Planning and Executing Interventional Procedures.

Percutaneous interventions aimed at addressing congenital and structural heart disease are simultaneously becoming more common and more complex as time progresses. An increasing number of heart defects that had previously required open heart surgery can now be successfully addressed in the cardiac catheterization laboratory. Adequate preprocedural preparation for these novel, complex procedures is critical to ensure their success. Diagnostic data can be collected before the intervention and displayed in multiple formats during the procedure. Advanced cardiac imaging, including cardiac magnetic resonance and cardiac computed tomography form the basis of this preparatory information. Novel methods of displaying these images are becoming more widespread and more useful, including 3-D printed models, 3-D digital models displayed on a virtual or augmented reality system and 3-D digital models overlaid onto a fluoroscopy system. In this review we summarize these state-of-the-art technologies and how they are able to help interventional cardiologists push the boundaries of what is possible in the cardiac catheterization laboratory.

Multicenter Experience Evaluating Transcatheter Pulmonary Valve Replacement in Bovine Jugular Vein (Contegra) Right Ventricle to Pulmonary Artery Conduits.

BACKGROUND: Follow-up of transcatheter pulmonary valve replacement (TPVR) with the Melody valve has demonstrated good short-term and long-term outcomes, but there are no published studies focused on valve performance in the Contegra bovine jugular vein conduit. METHODS AND RESULTS: This is a retrospective, multicenter study of the short- and intermediate-term outcomes of Melody TPVR within the Contegra conduit in the right ventricle to pulmonary artery position. Data from 13 centers were included in the analysis. During the study period, 136 patients underwent 139 catheterizations for attempted Melody TPVR with a median follow-up of 3 years (1 day to 9.1 years). Of the 136 patients, 117 underwent successful Melody TPVR. Two patients underwent a second Melody TPVR. The majority of patients underwent placement of ≥1 stents before transcatheter pulmonary valve implantation. There was a significant reduction in peak conduit pressure gradient acutely after transcatheter pulmonary valve implantation (39 versus 10 mm Hg; P<0.001). At most recent follow-up, the maximum pulmonary valve gradient by echocardiogram remained significantly reduced relative to prevalve implant measurements (65.9 versus 27.3 mm Hg; P<0.001). The incidence of Melody transcatheter pulmonary valve stent fracture (3.4%) and infectious endocarditis (4.3%) were both low. Serious adverse events occurred in 3 patients. CONCLUSIONS: Melody TPVR in Contegra conduits is safe and effective and can be performed in a wide range of conduit sizes with preserved valve function and low incidence of stent fracture and endocarditis.

Cardiac findings in fetal and pediatric autopsies: a five-year retrospective review.

This review aims to determine the spectrum of cardiac findings in our fetal and pediatric postmortem population and provide an analysis of associated extracardiac malformations and genetic abnormalities. Pediatric autopsy reports from 2003 to 2007 inclusive were reviewed and cases with cardiac pathology selected for analysis. Over the 5-year period, 119 cases (10.8%) with abnormal cardiac findings were identified from a total of 1102 postmortem examinations. Of these cardiac cases, 42% were after termination of pregnancy for fetal anomaly, 29% after fetal demise, 14% after neonatal unit death, 3% after hospital inpatient death, and 11% after sudden unexpected death. Structural abnormality cases numbered 107 (90%), with ventricular septal defect as the most common individual defect. Nonstructural abnormality cases, such as myocarditis, numbered 12 (10%). Extracardiac malformations were identified in 78%. Chromosome or gene aberrations were detected in 37%. This review highlights the potential benefit of introducing routine fetal anomaly scanning, the need for cardiac pathology training for pediatric pathologists, and the importance of examination of the heart and associated vessels in all cases to provide parents with as much information as possible and aid identification of the etiology and associations of cardiac pathology.