Detecting deceased patients on cardiac device remote monitoring: A case series and management guide for cardiac device services

BACKGROUND

Remote monitoring (RM) of implantable cardiac devices provides substantial and complex information, presenting new challenges such as detection of a patient's death.

OBJECTIVE

This study aims to describe RM transmissions indicating death and propose a management strategy for services.

METHODS

The study included consecutive ambulatory outpatients whose deaths were detected via RM. Clinical and device data were collected from electronic records, and ethical approval was obtained from the service's institutional review board.

RESULTS

Over a 9-year period (2014-2023), 28 patients were detected. The deceased patients had implantable cardioverter-defibrillators, pacemakers, and implantable loop recorders. In 54% of the cases, the patient's death had already been recognized. Alert transmissions indicating death were commonly related to ventricular arrhythmia events, but also due to lead measurements, and implantable loop recorder battery status. Several diagnostic features may indicate a patient's death. The most reliable was the presenting electrogram, demonstrating base rate pacing with no capture. Device diagnostics, lead parameters, and arrhythmia recordings may indicate death; however, not all cases present with recordings and diagnosis may not be conclusive. A majority (82%) had ventricular arrhythmia at the time of death. In cases where defibrillator shocks were delivered, the arrhythmia reinitiated shortly after successful cardioversion. Delayed therapy was observed, and some patients did not receive defibrillator shocks because of discriminators or because the arrhythmia rate fell below the shock zone.

CONCLUSION

Detecting a patient death via RM presents unique challenges and considerations for services. Standard operational policies and legal consultation should be established to address the implications.

Quiet timer blanking in a dog with sick sinus syndrome and a permanent transvenous pacemaker

A 14-year-old, 5.8 kg (12.7 lb) male castrated Jack Russell Terrier was referred for investigation of syncope and an arrhythmia. Electrocardiogram showed pronounced variation in the sinus rate including long periods of sinus arrest and an inconsistent escape rhythm. Sick sinus syndrome was the presumptive diagnosis. A single lead permanent transvenous pacemaker was implanted and was programmed to perform ventricular-demand pacing. Postoperative pacemaker interrogation revealed undersensing and asynchronous pacing during episodes of supraventricular tachycardia (SVT). This intermittent pacemaker malfunction was attributed to a specific pacemaker programming feature called quiet timer blanking. Adjustment of pacemaker parameters did not restore normal function. Treatment with sotalol (5 mg per os q 12 h) was used to medically treat the SVT, and asynchronous pacing was not observed during follow-up visits. To the authors' knowledge, this is the first documented case of quiet timer blanking causing paroxysmal undersensing and asynchronous pacing in a dog with a permanent pacemaker.

Subcutaneous implantable cardioverter defibrillators in patients with left ventricular assist devices: case report and comprehensive review

Background

Left ventricular assist devices (LVAD) are increasingly used in patients with advanced heart failure, many of whom have been or will be implanted with an implantable cardioverter defibrillator (ICD). Interaction between both devices is a matter of concern. Subcutaneous ICD (S-ICD) obtains its signals through subcutaneous vectors, which poses special challenges with regards to adequate performance following LVAD implantation.

Case summary

We describe the case of a 24-year-old man implanted with an S-ICD because of idiopathic dilated cardiomyopathy, severe biventricular dysfunction, and self-limiting sustained ventricular tachycardias. After the implantation of a HeartMate 3™ (Left Ventricular Assist System, Abbott) several months later, the S-ICD became useless because of inappropriate sensing due to electromagnetic interference and attenuation of QRS voltage.

Discussion

We reviewed the reported cases in PubMed about the concomitant use of S-ICD and LVAD. Seven case reports about the performance of S-ICD in patients with an LVAD were identified, with discordant results. From these articles, we analyse the potential causes for these differing results. Pump location and operating rates in LVAD, as well as changes in the subcutaneous-electrocardiogram detected by the S-ICD after LVAD implantation are related to sensing disturbances when used in the same patient.

Reiterative ventricular fibrillation caused by R-on-T during temporary epicardial pacing: a case report

Epicardial pacemaker wire insertion is standard following cardiothoracic surgery. However, undersensing of pacing wires may cause the R-on-T phenomenon, which induces ventricular fibrillation. We report a case of a male patient with severe mitral regurgitation scheduled for mitral valve replacement who experienced two ventricular fibrillation episodes related to the R-on-T phenomenon caused by undersensing of the epicardial pacing wire. Both undersensing events happened despite an appropriately low sensing threshold. Notably, the stimulated T wave followed the QRS of the premature ventricular contraction (PVC). This case suggests that a PVC’s R wave may be undersensed despite a low sensing threshold. This critical complication may have occurred because pacemakers sense R waves using a slew rate, which is the quotient of voltage over time. As a result, pacemakers may undersense wide QRS waves such as PVCs. Avoiding this dangerous phenomenon completely is not possible using epicardial pacemakers; therefore we recommend carefully adapting epicardial pacing especially when PVC waves occur frequently.

Epileptic seizure in a patient with an implantable cardioverter-defibrillator: Quo vadis right ventricular lead?

The case of a 77-year-old man admitted for suspected epileptic seizure is reported. Patient history showed implantation of a single-chamber implantable cardioverter-defibrillator (ICD) after cardiac arrest in 2007 with replacement in 2012 due to battery depletion; the patient reported no previous syncope, unconsciousness or seizures. Interrogation records of the ICD showed five ventricular tachyarrhythmia episodes that corresponded to the "seizure". Further examination revealed incorrect position of the RV-lead. Diagnosis was a provoked epileptic seizure due to undersensing of ventricular tachycardia because of improper ICD lead implantation in the coronary sinus. Treatment consisted of implantation of a new device with an additional ICD lead into the right ventricle.

Investigation of optimal position for implantable loop recorders by potential mapping with Reveal DX

BACKGROUND

Electrode positioning is important for the operation of implantable loop recorders (ILRs). This study aimed to investigate optimal electrode positions for the implantation of ILRs.

METHODS

Fifteen male subjects participated in the study and R wave amplitude data were collected from 15 areas in the left anterior chest area, with 4 variations of electrode angles and body positions.

RESULTS

The estimated minimum R wave amplitude values were greater than 0.3 mV (manufacturer-recommended value) when electrodes were angled vertically and positioned on the midclavicular line of the third and the forth intercostal spaces or on the left sternal border of the fourth and fifth intercostal space and when angled at 45° to the right on the left sternal border of the third and the forth intercostal space.

CONCLUSIONS

Exploring areas around the left sternal border of the fourth intercostal space - where the R wave amplitudes are least affected by body positions - is a reliable method for choosing implantation locations for ILRs.