In this work, we report an energy-efficient switched capacitor based millimeter-scale pacemaker (5 mm ×7.5 mm) and a multi-receiver wireless energy transfer system operating at around 200 MHz, and use them in a proof-of-concept multi-site heart pacing study. Two pacemakers were placed on two beating Langendorff rodent heart models separately. By utilizing a single transmitter positioned 20-30 cm away, both Langendorff hearts captured the stimuli simultaneously and were electromechanically coupled. This study provides an insight for future energy-efficient and distributed cardiac pacemakers that can offer cardiac resynchronization therapies.
A 78-year-old man presented with worsening dyspnea and edema. He had undergone coronary artery bypass grafting in 2001. At the current presentation, he had ischemic cardiomyopathy with a left ventricular (LV) ejection fraction of 0.20 and was taking home inotropic therapy. Two months previously, he had begun cardiac resynchronization therapy with use of an implanted biventricular pacemaker.Physical examination revealed elevated jugular venous pressure, bibasilar crackles, and pitting edema above both knees. An electrocardiogram (ECG) was obtained (Fig. 1).What is the cause of this ECG pattern?The patient's baseline ECG 2 months earlier (Fig. 2) had shown atrioventricular sequential biventricular pacing with a V-V interval programmed at 80 ms, and with LV pacing preceding that of the RV. There was a prolonged isoelectric period, followed by a dominant R wave in lead V1. This pattern confirms the contribution of LV pacing preceded by a prolonged latency from the pacer spike.In contrast, the patient's presenting ECG shows a QS pattern in lead V1, as well as an S wave in leads I and aVL (Fig. 1). This pattern indicates an RV preponderance of the depolarization pattern consistent with loss of LV lead capture.1A frequently used algorithm for determining loss of LV lead capture requires an R/S ratio <1 in lead V1, and >1 in lead I.2 The algorithm has a sensitivity of 94% and a specificity of 96%. Both criteria were evident on our patient's ECG.Loss of LV lead capture has substantial clinical implications. Investigators who studied the specific effects of acute lead dislodgments reported an adjusted odds ratio of 5.62 for the combined endpoints of cardiac arrest, tamponade, pneumothorax, and infection—and a 2.66 odds ratio for in-hospital death.3 Recognizing loss of LV lead capture early might help to mitigate adverse outcomes if successful, timely cardiac resynchronization can be achieved.
ABSTRACT Background Active esophageal cooling reduces the incidence of endoscopically identified severe esophageal lesions during radiofrequency (RF) catheter ablation of the left atrium for the treatment of atrial fibrillation. No atrioesophageal fistula (AEF) has been reported to date with active esophageal cooling, and only one pericardio-esophageal fistula has been reported; however, a formal analysis of the AEF rate with active esophageal cooling has not previously been performed. Methods Atrial fibrillation ablation procedure volumes before and after adoption of active cooling using a dedicated esophageal cooling device (ensoETM, Attune Medical) were determined across 25 hospital systems with the highest total use of esophageal cooling during RF ablation. The number of AEFs occurring in equivalent time frames before and after adoption of cooling were then determined, and AEF rates were compared using generalized estimating equations robust to cluster correlation. Results Throughout the 25 hospital systems, which included a total of 30 separate hospitals, 14,224 patients received active esophageal cooling during RF ablation, with the earliest adoption beginning in March 2019 and the most recent beginning in March 2022. In the time frames prior to adoption of active cooling, a total of 10,962 patients received primarily luminal esophageal temperature (LET) monitoring during their RF ablations. In this pre-adoption cohort a total of 16 AEFs occurred, for an AEF rate of 0.146%, in line with other published estimates of <0.1% to 0.25%. No AEFs were found in the cohort treated after adoption of active esophageal cooling, yielding an AEF rate of 0% (P<0.0001). Conclusion Adoption of active esophageal cooling during RF ablation of the left atrium for the treatment of atrial fibrillation was associated with a significant reduction in AEF rate.
Abstract Introduction Epicardial catheter ablation is increasingly used to treat arrhythmias with an epicardial component. Nevertheless, percutaneous epicardial access remains associated with a significant risk of major complications. Developing a technology capable of confirming proper placement within the pericardial space could decrease complication rates. The purpose of this study was to examine differences in bioimpedance among the pericardial space, anterior mediastinum, and right ventricle. Methods An ovine model (n = 3) was used in this proof‐of‐concept study. A decapolar catheter was used to collect bipolar impedance readings; data were collected between each of five electrode pairs of varying distances. Data were collected from three test regions: the pericardial space, anterior mediastinum, and right ventricle. A control region in the inferior vena cava was used to normalize the data from the test regions. Analysis of variance was used to test for differences among regions. Results A total of 10 impedance values were collected in each animal between each of the five electrode pairs in the three test regions (n = 340) and the control region (n = 145). The average normalized impedance values were significantly different among the pericardial space (1.760 ± 0.370), anterior mediastinum (3.209 ± 0.227), and right ventricle (1.024 ± 0.207; P < 0.0001). In post hoc testing, the differences between each pair of regions were significant, as well (P < 0.001 for all). Conclusion Impedance values are significantly different among these three anatomical compartments. Therefore, impedance can be potentially used as a means to guide percutaneous epicardial access.
We present a battery-less mm-sized wirelessly powered pacemaker microchip with on-chip antenna in 180nm CMOS process. The microchip harvests RF radiation from an external source in the X-band frequency, with the size of 4mm by 1mm. The in-vivo experiment is demonstrated successfully on a live pig heart. The pacemaker can be wirelessly powered with a distance of 2cm. It generates a stimulation pulse signal with a voltage magnitude of 1.3V. The wireless pacing testing was successfully demonstrated by changing the heart rhythm frequency from 1.67Hz to 2.87Hz.
