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  • br Method br Results br

    2019-06-25


    Method
    Results
    Discussion
    Conclusions
    Conflict of interest
    Acknowledgments
    Introduction Cardiac sarcoidosis is a known cause of atrioventricular (AV) block, especially in younger people. Its progression can lead to ventricular tachycardia or heart failure [1]. Steroid therapy or immune suppressive therapy is moderately effective in the treatment of cardiac sarcoidosis [2,3], provided it is diagnosed early. Cardiac MRI is an important diagnostic tool for cardiac sarcoidosis [4]. However, until recently, since MRI conditional pacemakers and ICDs were approved for use, the use of MRI was contraindicated in patients with implanted devices [5,6].
    Case report A 50-year-old man presented to the emergency department with repeated episodes of fainting and exertional dyspnea for 10 days, and was found to have an AV block. Chest radiography and transthoracic echocardiography results were normal, without any evidence of heart failure, wall motion abnormalities, interventricular septum thinning, or bilateral hilar lymphadenopathy. A temporary pacemaker was implanted, followed by a permanent pacemaker. Subsequent chest computed tomography (CT) with Lubiprostone molecular enhancement did not show any abnormalities, including patent coronary arteries, lymph node adenopathy, and pulmonary abnormalities. An MRI conditional dual chamber pacemaker and leads (Advisa DR MRI™ SureScan™ with 5086 leads; Medtronic, Minneapolis, USA) were thereafter implanted (Fig. 1). Six weeks following the implant, a cardiac MRI was performed to test for cardiac sarcoidosis. Although cine imaging showed normal left and right ventricular function, late gadolinium enhancement demonstrated multiple enhanced uptakes (Fig. 2). Gallium scintigraphy revealed multiple uptakes in the heart, along with axillary and inguinal lymph nodes (Fig. 3). A PET–CT of the heart demonstrated multiple enhanced uptakes appearing on the interventricular septum and left ventricular free wall (Fig. 4).
    Discussion MRI can induce several hazardous effects, including device inhibition, rapid pacing, mechanical torque and rotation of the device, device failure, resetting, and lead heating. Therefore, the components in MRI conditional devices have been redesigned to minimize the energy induced and discharged due to static, gradient, and combined field effects. This includes protecting the power supply circuit, changing the lead design to minimize and attenuate any radiofrequency energy discharges at the tip, changing firmware to provide MRI conditional protection, and changing from a reed-switch to a Hall sensor [7]. Moreover, a specific MRI conditional mode was created to ensure appropriate device operation and pacing therapy. Owing to these changes, MRI conditional devices were deemed clinically safe for use [8]. In relatively younger patients who present with AV block, cardiac sarcoidosis should be considered a differential diagnosis [9]. Steroid or immunosuppressive therapy should be initiated if the disease is in the active stage [10]. During the chronic phase of cardiac sarcoidosis, cardiac MRI is useful for evaluating disease progression or scar characteristics of the substrate of a ventricular arrhythmia [11].
    Conclusions
    Conflict of interest
    Case report A 67-year-old man with non-obstructive hypertrophic cardiomyopathy had received a dual-chamber implantable cardioverter-defibrillator (ICD) (7278 Maximo® DR, Medtronic, Minneapolis, MN, USA) 5 years earlier for an unstable, sustained ventricular tachycardia (VT) induced by programmed stimulation during an electrophysiological study (EPS). The ICD was programmed to provide atrial overdrive suppression for paroxysmal atrial fibrillation and to avoid unnecessary ventricular pacing. The electrophysiological study (EPS) record during ICD implantation revealed a maximum sinus node recovery time of 11,100ms; moreover, the patient\'s 12-lead electrocardiogram (ECG) showed first-degree atrioventricular block (DDIR) with a lowered heart rate of 80beats/min (bpm). The atrioventricular (AV) delay after atrial pacing was 350ms. The postventricular atrial refractory period (PVARP) was maintained at 310ms for containing retrograde ventriculoatrial (VA) conduction, with a VA conduction time of approximately 190ms. In addition, we prescribed 160mg/day sotalol to prevent ventricular tachycardia.