Left Axillary Implantation of Loop Recorder

Background: We compared the clinical course of 10 patients who received an implantable loop recorder (ILR) at a traditional site with 11 patients whose ILRs were implanted via a subpectoral site via a left axillary approach without complications. Methods and Results: R‐wave amplitude was determined at implantation and during follow‐up. Each patient was followed after 7 days to optimize device setting and then at 1 and 3 months. The R‐wave amplitude obtained with the new technique was significantly higher and more stable than that obtained with the standard procedure. Our preliminary experience suggests that axillary access for ILR implantation is feasible, safe, well tolerated, and reliable in terms of sensing function and device performance. Moreover, it is superior aesthetically to the standard approach and carries the potential of minimizing permanent scarring after ILR extraction. (PACE 2010; 999–1002)     

Electromagnetic Interference of an Implantable Loop Recorder by Commonly Encountered Electronic Devices

De COCK, C.C., et al. : Electromagnetic Interference of an Implantable Loop Recorder by Commonly Encountered Electronic Devices. Electromagnetic interference of pacemaker systems has been well established and can lead to an inappropriate function of these devices. Recently, an implantable loop recorder (ILR) (REVEAL, Medtronic Inc.) has been introduced to evaluate the possible arrhythmic etiology of patients with recurrent syncope. We evaluated the interference of this device in two patients with implantable ILR and in three nonimplanted ILRs with four electromagnetic sources: cellular phones (GSMs), electronic article surveillance systems (EASs), metal detector gates (MDGs), and magnetic resonance imaging (MRI). The GSM did not affect appropriate function of the ILR whereas radiofrequency (RF) EAS could interfere with normal function in implanted and nonimplanted systems. The MDG had no influence on ILR function. The magnetic field induced by the MRI resulted in an irreversible error in one nonimplanted ILR. Therefore, although interference between electromagnetic sources and ILRs appears to be rare in our study, physicians should be aware of possible malfunctioning of these devices.     

Demonstration of Myocardial Ischemia by an Internal Loop Recorder

VLAY, S.C., et al. : Demonstration of Myocardial Ischemia by an Internal Loop Recorder. An internal loop recorder (ILR) implanted to evaluate syncope was activated during an episode of chest pain. Analysis of the recorded event revealed a marked increase in the amount of ST-segment depression over baseline. In addition to rhythm analysis, the ILR may be able to assess myocardial ischemia. Further refinements of filtering may make analysis more accurate.     

Maturation of the Sensed Electrogram Amplitude Over Time in a New Subcutaneous Implantable Loop Recorder

The cause of recurrent syncope may be difficult to determine if the diagnosis is not establisbed from initial noninvasive and invasive testing. Eighteen patients with recurrent syncope and negative tilt table and electrophysiological testing underwent implantation of a left pectoral subcutaneous loop recorder. This device "freezes" the preceding 7.5 or 15 minate rhythm strip after magnet application after spontaneous syncope. Baseline and follow-up electrograms were routinely recorded, and patients were followed until syncope recurred. Three patients bad syncope within 1 month of implantation and were excluded from this report. Implantation electrogram amplitude was 250 ±124 /μV and increased to 291 ±114 μV at 2–3 months, and increased further to 353 ± 167 μV at 4–6 months (P < 0.001, ANOVA). Syncope recurred in 14 of the 15 patients. An arrhythmic basis for syncope was established (n = 7) or excluded (n = 7) in every patient who had recurrent syncope. All syncopal episodes were associated with diagnostic sensed electrograms. The increase in sensed electrogram amplitude over time suggests a maturation of the device-tissue interface. These results support the long-term viability of this implantable monitoring technique.     

How Revealing Are Insertable Loop Recorders in Pediatrics?

Introduction: An insertable loop recorder (ILR) in patients with infrequent syncope or palpitations may be useful to decide management strategies, including clinical observation, medical therapy, pacemaker, or implantable cardioverter defibrillator (ICD). We sought to determine the diagnostic utility of the Reveal® ILR (Medtronic, Inc., Minneapolis, MN, USA) in pediatric patients. Methods: Retrospective review of clinical data, indications, findings, and therapeutic decision in 27 consecutive patients who underwent ILR implantation from 1998–2007. Results: The median age was 14.8 years (2–25 years). Indications were syncope in 24 patients and recurrent palpitations in three. Overall, eight patients had structural heart disease (six congenital heart disease, one hypertrophic cardiomyopathy, one Kawasaki), five had previous documented ventricular arrhythmias with negative evaluation including electrophysiology study, and three patients had QT prolongation. Tilt testing was performed in 10 patients, of which five had neurocardiogenic syncope but recurrent episodes despite medical therapy. After median three months (1–20 months), 17 patients presented with symptoms and the ILR memory was analyzed in 16 (no episode stored in one due to full device memory), showing asystole or transient atrioventricular (AV) block (2), sinus bradycardia (6), or normal sinus rhythm (8). Among asymptomatic patients, 3/10 had intermittent AV block or long pauses, automatically detected and stored by the ILR. In 19 of 20 patients, ILR was diagnostic (95%) and five subsequently underwent pacemaker implantation, while seven patients remained asymptomatic without ILR events. Notably, no life‐threatening events were detected. The ILR was explanted in 22 patients after a median of 22 months, two due to pocket infection, 12 for battery depletion and eight after clear documentation of nonmalignant arrhythmia. Conclusions: The ILR in pediatrics is a useful adjunct to other diagnostic studies. Patient selection is critical as the ILR should not be utilized for malignant arrhythmias. A diagnosis is attained in the majority of symptomatic patients, predominantly bradyarrhythmias including pauses and intermittent AV block.     

Heart Rhythm During Syncope and Presyncope: Results of Implantable Loop Recorders

NIEROP, P.R., et al. : Heart Rhythm During Syncope and Presyncope: Results of Implantable Loop Recorders. Ambulatory ECG monitoring in patients with recurrent syncope is nondiagnostic in the majority of cases. Recently, an ECG implantable loop recorder (ILR) has been introduced. The ILR performs continuous ECG monitoring over a period of at least 14 months. From February 1997 to September 1999, 35 patients underwent implantation of an ILR. During a mean follow-up of  11 ± 8 months  , 24 (69%) patients had recurrent syncope or presyncope events. Four (11%) patients were not capable of activating the ILR to save the event. A symptom-rhythm correlation could be studied in 20 (83%) of 24 patients. Forty of 44 recurrences were captured by the ILR. There were 14 (40%) patients with at least one syncopal episode. An arrhythmic cause for syncope was found in eight of them (bradycardia in four and tachycardia in four). In the other six patients the heart rhythm was normal. In 17 (49%) patients with 1-year follow-up, the mean syncope event rate 12 months before ILR implantation was  4.7 ± 2.4  , whereas the mean syncope event rate 12 months after ILR implantation was  1.3 ± 0.7  (  P < 0.01  ). Resolution of symptoms was observed in 6 (17%) patients. These patients were significantly younger than patients without resolution (  50 ± 18 vs 69 ± 14 years, p < 0.01  ) and five were women. Three (9%) patients died during follow-up, all of them were noncompliant during their follow-up. In conclusion, the ILR made symptom—rhythm correlation possible in 83% of patients with recurrent syncope. Syncope recurrences decreased significantly after implantation of the device, especially in the younger patients. Noncompliant patients had a high mortality rate.     

Insertable loop recorder use for detection of intermittent arrhythmias

The advent of prolonged monitoring with the implanted loop recorders has revolutionized the quest for detection of elusive infrequent arrhythmias in patients with unexplained syncope. The capability of prolonged monitoring has permitted us to obtain symptom rhythm correlation in the majority of patients suspected to have underlying infrequent arrhythmia. The implanted loop recorder is easily implanted in the left pectoral region with a minimally invasive procedure, providing at least 14 months of continuous monitoring that is both patient and automatically activated. Several recent studies suggest that it plays a major role in patients with infrequent symptoms and suspected arrhythmia, including patients with syncope and conduction disturbances, mild to moderate underlying heart disease, and atypical epilepsy. In a randomized trial, the device was found to be cost-effective and improved diagnostic yield compared to conventional tilt and electrophysiological testing. Wider application of prolonged monitoring is ongoing, including assessment of ventricular arrhythmias, atrial fibrillation, and conduction disturbances. The implantable loop recorder is most useful in patients with infrequent unexplained syncope when noninvasive testing is negative.     

Holter, Loop Recorder, and Event Counter Capabilities of Implanted Devices

The current generation of cardiac pacemakers and implantable cardioverter defibrillators almost all have some capabilites to store data regarding device activity and patient events for future retrieval. This information may provide valuable information regarding device function and whether this is proving valuable in patient management. Examples include "pace-sense" counters, which can reveal under sensing of patient events, and serial lead impedance measurements, which are able to demonstrate trends not seen on isolated measurements. Holter capabilities become vital in more advanced devices for documenting the utility of, and fine tuning the programming of, features such as antitachycardia pacing, rate-responsiveness, and mode-switching. Finally, the ability to store patient events as marker channels and even intrac-ardiac electrograms adds a diagnostic capability not available through external monitoring. This role has now been advanced by the development of a purely diagnostic implantable loop recorder.     

Feasibility of the inframammary location for insertable loop recorders in young women and girls

The parasternal location for the insertable loop recorder (ILR) has potential for erosion in small patients, and can be aesthetically unappealing, especially for young women. We assessed the feasibility of the inframammary location in nine patients, utilizing a 2 cm transverse incision at the inferior and medial border of the left or right breast. Signal quality was adequate with clearly discernable atrial and ventricular electrograms. No complications involving the surgical site were observed. Cosmetically, placement of the scar in the natural breast crease has been favorably accepted. Inframammary implantation of the ILR is feasible, and is the preferred method in young women and girls at our center. (PACE 2004; 27:492–494)     

Orthotripsy mimicking asystole

An insertable loop recorder implanted to evaluate dizziness, documented an apparent arrhythmia during an orthotripsy procedure. Review of the tracing revealed artefact related to an electrostatic discharge that should not be mistaken for ventricular asystole. (PACE 2004; 27:1)     

Sensing Performance of a New Wireless Implantable Loop Recorder: A 12‐Month Follow Up Study

Background: The implantable loop recorder (ILR) is a cost‐effective tool with a high diagnostic yield in the evaluation of unexplained recurrent syncope. The Sleuth ILR (Transoma Medical, St. Paul MN, USA) is a new‐generation ILR with wireless transmission capability approved by the Food and Drug Administration. We report the feasibility of achieving appropriate sensing over 1‐year follow‐up at the traditional midclavicular and alternative inframammary implantation sites without preimplant electrocardiogram (ECG) mapping. Methods and Results: We studied 32 patients with unexplained syncope, aged 58.4±18.44 years, with an ILR implanted at the left midclavicular location (n = 17) or the left inframammary site (n = 15) over 1‐year post implant. No preimplant electrocardiogram (ECG) mapping was performed. The highest R‐wave amplitudes were observed at the inframammary site, but over the entire follow‐up period, amplitudes were not significantly different from those at the midclavicular site. At both sites, R‐wave amplitudes at the 6‐month follow‐up were significantly higher than those measured at 1 week. P‐waves were visible in 80–90% of the patients. There was no discernible difference in P‐waves (amplitude) relative to implant location. Body mass index, left ventricular ejection fraction, and age did not significantly influence the R‐wave amplitude or the ability to discern P‐waves. Conclusion: Our findings show that the Sleuth ILR implanted at both the midclavicular and inframammary locations without preimplant ECG mapping achieves acceptable “R” waves. This may simplify implantation procedures and improve patient satisfaction. (PACE 2010; 834–840)     

Beta Adrenergic Blockade in the Treatment of Sustained Ventricular Tachycardia or Ventricular Fibrillation

The value of β-blockers as antiarrhythmic drugs in patients with sustained VT or VF has received only little attention. This article summarizes the current state of knowledge regarding the identification of patients with sustained VT or VF with the highest benefit of β-blockade. The antiarrhythmic mechanisms of β-blockade and its efficacy as single or adjuvant therapy in patients with sustained VT or VF are reviewed. Current insights into the effects of β-blockade in patients suffering from VT, in particular in the setting of heart failure, are discussed and future directions are considered.     

Double Ventricular Response by a Single Ventricular Extrastimulus to the Inner Loop of Reentry in a Patient Without Apparent Heart Disease

SHIMIZU, A., et al. : Double Ventricular Response by a Single Ventricular Extrastimulus to the Inner Loop of Reentry in a Patient Without Apparent Heart Disease. In a patient without apparent heart disease, a ventricular extrastimulus delivered from the left ventricular apex where the electrogram was recorded 30 ms after the onset of the QRS complex during VT advanced the second QRS complex, but not the first QRS complex. The morphology of the second QRS complex was the same as that of VT. The postpacing interval was the same as the cycle length of the VT. These findings indicated that the site of stimulation was at the inner loop of the reentry circuit of the VT. A ventricular extrastimulus with a shorter coupling interval advanced the first and second QRS complexes, indicating that the ventricle was activated by antidromic and orthodromic activation from the extrastimulus. Radiofrequency ablation at that site of stimulation terminated the VT and no further VT could be induced.     

Unexpected Coexistence of Supraventricular and Ventricular Tachycardia in Patients with Syncope

The incidence of multiple, inducible sustained arrhythmias during electrophysiologic studies is unknown. We have identified five patients who had several sustained tachycardias, some of which were not previously recognized clinically. Three patients had documented sustained supraventricular tachycardia (one of these also had nonsustained ventricular tachycardia) and two had documented sustained ventricular tachycardia. The clinically documented tachycardia was successfully reproduced in all cases; however, the three cases of supraventricular tachycardia also had sustained ventricular tachycardia initiated, and the two cases of ventricular tachycardia also had sustained supraventricular tachycardia, which had not previously been seen. The underlying common denominators for all five patients were poor left ventricular function due to ischemic heart disease and a history of syncope. In one case of clinical supraventricular tachycardia, the second sustained tachycardia appeared following drug therapy (procainamide), which seemed to convert nonsustained to sustained ventricular tachycardia. In another patient with clinical ventricular tachycardia, the supraventricular tachycardia was also initiated following drug therapy (indecainide). We conclude that: (1) patients with syncope may have multiple arrhythmic etiologies and (2) complete electrophysiologic evaluation, during control studies as well as serial drug studies, are important in the management of these patienls.     

Psychogenic Syncope? A Cautionary Note

Introduction: In some patients with recurrent syncope, the etiology may remain unclear despite extensive evaluation. These patients may sometimes be labeled as having a "psychogenic" cause for their syncope.
Methods: We report on three patients with recurrent unexplained syncope (despite extensive evaluation) who were labeled as having a psychogenic cause for their events. In each patient following placement of an implantable loop recorder, their syncopal events were found to be due to periods of prolonged asystole and/or complete heart block. One patient had prolonged asystole for 44 seconds. In each patient, episodes of syncope were eliminated following permanent pacemaker implantation.
Conclusion: We conclude that physicians should exercise great caution before labeling any patient's syncope as psychogenic and that prolonged monitoring may be necessary to exclude a potential cardiac rhythm-related etiology.     

Syncope masquerading as a panic disorder: role of the subcutaneous loop recorder in eliciting the appropriate diagnosis

The present case describes a 49-year-old woman with apparent panic disorder in whom the Reveal Plus, a newly developed subcutaneous loop recorder, was used to show that the panic attacks were secondary to prolonged episodes of ventricular asystole.