Feasibility of adenosine stress cardiovascular magnetic resonance perfusion imaging in patients with MR-conditional transvenous permanent pacemakers and defibrillators

Background The use of stress perfusion-cardiovascular magnetic resonance (CMR) imaging remains limited in patients with implantable devices. The primary goal of the study was to assess the safety, image quality, and the diagnostic value of stress perfusion-CMR in patients with MR-conditional transvenous permanent pacemakers (PPM) or implantable cardioverter-defibrillators (ICD). Methods Consecutive patients with a transvenous PPM or ICD referred for adenosine stress-CMR were enrolled in this single-center longitudinal study. The CMR protocol was performed using a 1.5 T system according to current guidelines while all devices were put in MR-mode. Quality of cine, late-gadolinium-enhancement (LGE), and stress perfusion sequences were assessed. An ischemia burden of ≥ 1.5 segments was considered significant. We assessed the safety, image quality and the occurrence of interference of the magnetic field with the implantable device. In case of ischemia, we also assessed the correlation with the presence of significant coronary lesions on coronary angiography. Results Among 3743 perfusion-CMR examinations, 66 patients had implantable devices (1.7%). Image quality proved diagnostic in 98% of cases. No device damage or malfunction was reported immediately and at 1 year. Fifty patients were continuously paced during CMR. Heart rate and systolic blood pressure remained unchanged during adenosine stress, while diastolic blood pressure decreased (p = 0.007). Six patients (9%) had an ischemia-positive stress CMR and significant coronary stenoses were confirmed by coronary angiography in all cases. Conclusion Stress perfusion-CMR is safe, allows reliable ischemia detection, and provides good diagnostic value.

Magnetic Resonance Imaging of the Knee in the Presence of Bridging External Fixation: A Comparative Experimental Evaluation of Four External Fixators, Including Dolphix®

Performing MR investigation on patients instrumented with external fixators is still controversial. The aim of this study is to evaluate the quality of MR imaging of the knee structures in the presence of bridging external fixators. Different cadaveric lower limbs were instrumented with the MR-conditional external fixators Hofmann III (Stryker, Kalamazoo, MI, USA), Large external Fixator (DePuy Synthes, Raynham, MA, USA), XtraFix (Zymmer, Warsaw, IN, USA) and a newer implant of Ketron Peek CA30 and ERGAL 7075 pins, Dolphix®, (Citieffe, Bologna, Italy). The specimens were MR scanned before and after the instrumentation. The images were subjectively judged by a pool of blinded radiologists and then quantitatively evaluated calculating signal intensity, signal to noise and contrast to noise in the five regions of interest. The area of distortion due to the presence of metallic pins was calculated. All the images were considered equally useful for diagnosis with no differences between devices (p > 0.05). Only few differences in the quantification of images have been detected between groups while the presence of metallic components was the main limit of the procedure. The mean length of the radius of the area of distortion of the pins were 53.17 ± 8.19 mm, 45.07 ± 4.33 mm, 17 ± 5.4 mm and 37.12 ± 10.17 mm per pins provided by Zimmer, Synthes, Citieffe and Stryker, respectively (p = 0.041). The implant of Ketron Peek CA30 and ERGAL 7075 pins showed the smallest distortion area.

Temporary device malfunction of an MR conditional cardiac resynchronization defibrillator when undergoing MRI without appropriate re-programming: a case report

Background Magnetic resonance (MR) imaging (MRI) for patients with implantable cardiac devices is becoming more routine, with the development of MR conditional devices allowing more patients access to the imaging they need. However, for this to be performed safely, strict protocols must be followed necessitating close collaboration between cardiology and radiology departments. We present a case where mandatory device re-programming of a cardiac resynchronization therapy defibrillator device into MRI mode was not performed pre-scan leading to temporary device dysfunction with no clinical consequences. Case summary A 72-year-old man presented to a device clinic for a routine device interrogation. An atrial tachycardia response episode was recorded at the same time as the patient reported having undergone an MRI scan at a local centre. The electrogram demonstrated temporary right ventricular loss of capture with standard output programming, and a short episode of oversensing on the atrial and ventricular channel which was not sustained for long enough to meet tachycardia detection. Discussion We demonstrate two potential electrophysiological effects of MRI on pacemakers, where the device had not been appropriately re-programmed pre-procedure. This illustrates that whilst MRI in patients with implantable cardiac devices is safe, strict protocols must be followed requiring robust multidisciplinary communication.

Subclinical cardiac perforation by cardiac implantable electronic device leads detected by cardiac computed tomography

Background The relationship between the characteristics of cardiac implantable electronic device (CIED) leads and subclinical cardiac perforations remains unclear. This study aimed to evaluate the incidence of subclinical cardiac perforation among various CIED leads using cardiac computed tomography (CT). Methods A total of 271 consecutive patients with 463 CIED leads, who underwent cardiac CT after CIED implantation, were included in this retrospective observational study. Cardiac CT images were reviewed by one radiologist and two cardiologists. Subclinical perforation was defined as traversal of the lead tip past the outer myocardial layer without symptoms and signs related to cardiac perforation. We compared the subclinical cardiac perforation rates of the available lead types. Results A total of 219, 49, and 3 patients had pacemakers, implantable cardioverter-defibrillators, and cardiac resynchronization therapy, respectively. The total subclinical cardiac perforation rate was 5.6%. Subclinical cardiac perforation by screw-in ventricular leads was significantly more frequent than that caused by tined ventricular leads (13.3% vs 3.3%, respectively, p = 0.002). There were no significant differences in the incidence of cardiac perforation between atrial and ventricular leads, screw-in and tined atrial leads, pacing and defibrillator ventricular leads, nor between magnetic resonance (MR)-conditional and MR-unsafe screw-in ventricular leads. Screw-in ventricular leads were significantly associated with subclinical cardiac perforation [odds ratio, 4.554; 95% confidence interval, 1.587–13.065, p = 0.005]. There was no case subclinical cardiac perforation by septal ventricular leads. Conclusions Subclinical cardiac perforation by screw-in ventricular leads is not rare. Septal pacing may be helpful in avoiding cardiac perforation.

Safety, feasibility and prognostic value of stress perfusion CMR in patients with pacemaker

Funding Acknowledgements Type of funding sources: None. BACKGROUND Several studies have shown the excellent prognostic value of stress cardiovascular magnetic resonance (CMR). However, its prognostic value in patients with pacemaker (PM) remains unknown because most studies excluded PM patients. PURPOSE This study aimed to assess the prognostic value of vasodilator stress perfusion CMR in patients with PM. METHODS Consecutive patients with MR-conditional pacemakers referred for stress perfusion CMR at 1.5 T were followed for the occurrence of major adverse cardiovascular events (MACE), defined by cardiovascular death or nonfatal myocardial infarction. Cox regressions analyses were performed to determine the prognostic value of CMR-parameters. The quality of CMR was rated by two observers blinded to clinical details. Data on pacemaker and leads were collected pre- and post-CMR. RESULTS Of 224 patients who completed the stress CMR protocol, 2 patients had inconclusive stress CMR due to artefact and 203 patients (72.9% male, mean age 71.4 ± 8.7 years) completed the follow-up (median [interquartile range], 7.0 [5.2-7.3] years). Among those, 23 experienced a MACE (11.3%). Stress CMR was well tolerated with no major adverse events. All scans were completed successfully with no significant change in lead thresholds or pacing parameters. Overall, the image quality was rated good or excellent in 84.1% of segments. Using Kaplan-Meier analysis, inducible ischemia and late gadolinium enhancement (LGE) were significantly associated with the occurrence of MACE (hazard ratio, HR: 11.80 [95% CI, 4.63-30.30]; and HR: 6.74 [95% CI, 2.47-18.40], both p < 0.001; respectively). In multivariable Cox regression, inducible ischemia and LGE were independent predictors of a higher incidence of MACE (HR: 5.24 [95% CI, 2.61-14.40]; and HR: 2.98 [95% CI, 2.25-4.02]; both p < 0.001; respectively). In patients with ischemia, CMR-related coronary revascularization showed no benefit in reducing MACE (p = 0.25). CONCLUSION Stress CMR is safe, feasible and has a good discriminative prognostic value in consecutive patients with PM.

Body-Mounted Robotic System for MRI-Guided Shoulder Arthrography: Cadaver and Clinical Workflow Studies

This paper presents an intraoperative MRI-guided, patient-mounted robotic system for shoulder arthrography procedures in pediatric patients. The robot is designed to be compact and lightweight and is constructed with nonmagnetic materials for MRI safety. Our goal is to transform the current two-step arthrography procedure (CT/x-ray-guided needle insertion followed by diagnostic MRI) into a streamlined single-step ionizing radiation-free procedure under MRI guidance. The MR-conditional robot was evaluated in a Thiel embalmed cadaver study and healthy volunteer studies. The robot was attached to the shoulder using straps and ten locations in the shoulder joint space were selected as targets. For the first target, contrast agent (saline) was injected to complete the clinical workflow. After each targeting attempt, a confirmation scan was acquired to analyze the needle placement accuracy. During the volunteer studies, a more comfortable and ergonomic shoulder brace was used, and the complete clinical workflow was followed to measure the total procedure time. In the cadaver study, the needle was successfully placed in the shoulder joint space in all the targeting attempts with translational and rotational accuracy of 2.07 ± 1.22 mm and 1.46 ± 1.06 degrees, respectively. The total time for the entire procedure was 94 min and the average time for each targeting attempt was 20 min in the cadaver study, while the average time for the entire workflow for the volunteer studies was 36 min. No image quality degradation due to the presence of the robot was detected. This Thiel-embalmed cadaver study along with the clinical workflow studies on human volunteers demonstrated the feasibility of using an MR-conditional, patient-mounted robotic system for MRI-guided shoulder arthrography procedure. Future work will be focused on moving the technology to clinical practice.

Access to MRI for patients with cardiac pacemakers and implantable cardioverter defibrillators

ObjectiveTo determine provision of MRI for patients with cardiac implantable electronic devices (CIEDs; pacemakers and defibrillators) in England, to understand regional variation and assess the impact of guideline changes.MethodsRetrospective data related to MRI scans performed in patients with CIED over the preceding 12 months was collected using a structured survey tool distributed to every National Health Service Trust MRI unit in England. Data were compared with similar data from 2014/2015 and with demand (estimated from local CIED implantation rates and regional population data by sustainability and transformation partnerships (STPs)).ResultsResponses were received from 212 of 223 (95%) hospitals in England. 112 (53%) MRI units’ scan patients with MR-conditional CIEDs (10% also scan non-MR conditional devices), compared with 46% of sites in 2014/2015. Total annual scan volume increased over fourfold between 2014 and 2019 (1090 to 4896 scans). There was widespread geographical variation, with five STPs (total population >3·5 million representing approximately 25 000 patients with CIED) with no local provision. There was no correlation between local demand (CIED implantation rates) and MRI provision (scan volume). Complication rates were extremely low with three events nationally in 12 months (0·06% CIED–MRI scans).ConclusionsProvision of MRI for patients with CIEDs in England increased over fourfold in 4 years, but an estimated 10-fold care gap remains. Almost half of hospitals and 1 in 10 STPs have no service, with no relationship between local supply and demand. Availability of MRI for patients with non-MR conditional devices, although demonstrably safe, remains limited.