Search

Background: With the advent of conduction system pacing, use of the Medtronic SelectSecure Model 3830 lead has increased substantially. However, with this increased use, the potential need for lead extraction also will increase. Lumenless lead construction requires an understanding of both applicable tensile forces as well as lead preparation techniques that can influence consistent extraction., Objective: The purpose of this study was to use bench testing methodologies to characterize the physical properties of lumenless leads and to describe related lead preparation methods that support known extraction techniques., Methods: Multiple 3830 lead preparation techniques, commonly used in extraction practices, were compared on the bench to assess rail strength (RS) in simple traction and use conditions with simulated scar. Retention of the IS1 connector vs severing the lead body preparation techniques were compared. Distal snare and rotational extraction tools were evaluated., Results: The retained connector method provided higher RS compared to the modified cut lead method: mean 11.42 lbf (9.85-12.73 lbf) vs 8.51 lbf (1.66-14.32 lbf), respectively. Snare use distally did not significantly affect RS: mean 11.05 lbf (8.58-13.95 lbf). Lead damage occurred with the TightRail extraction tool at angles ≥90°, which could occur with right-sided implants., Conclusions: When extracting SelectSecure leads, the retained connector method to maintain cable engagement benefits preservation of the extraction RS. Limiting traction force to <10 lbf (4.5 kgf) and avoiding poor lead preparation methods are critical to consistent extraction. Femoral snaring does not change RS when needed and offers a method to regain lead rail in cases of distal cable fracture., (Copyright © 2023 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Background: Medtronic is developing an atrial Micra Transcatheter Pacing System (Medtronic, Minneapolis, Minnesota) and associated retrieval system., Objective: The purpose of this study was to evaluate chronic atrial Micra retrieval, reimplantation, and chronic pacing performance., Methods: Sheep were implanted in 2 groups: group 1 (n = 6) for 6 months, a second device implanted, and first retrieved and studied for an additional 6 months; group 2 (n = 6) for 6 months, devices were retrieved, and a second device implanted and observed acutely. Both groups underwent histopathological evaluation. Pacing capture thresholds (PCTs), p wave amplitude, and pacing impedances were measured chronically. Device retrieval times were recorded, and intracardiac echocardiography was used., Results: At 24 weeks, PCTs for group 1 were low and stable for both the first device (0.55 ± 0.14 V) and the second device (0.57 ± 0.09 V), in which the average retrieval time was 17:35 minutes. For group 2, the average retrieval time was 6:12 minutes, chronic PCTs in the first device were 0.53 ± 0.11 V, and acute PCTs for the second device were 0.71 ± 0.19 V. Pathological findings were within an expected range of tissue responses for similar Micra acute and chronic implants and device retrievals. p waves and impedances were stable and within an expected range for implant site and electrode design. Complications included 1 early dislodgment and 1 death attributed to a prototype retrieval tool., Conclusion: In an animal model, an atrial Micra can be easily implanted with excellent chronic pacing performance and is easily retrievable at 6 months. A second device can successfully be implanted with low, chronic stable thresholds. A developed prototype retrieval tool was easy to use and, with modifications, complication free., (Copyright © 2020 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Background: The number of lead extractions is growing because of the greater population and increasing age of individuals with a cardiac implantable electronic device. Lead extraction procedures can be complex undertakings with risk of significant mortality, and vascular tears in the superior vena cava are of greatest concern., Objective: The purpose of this study was to study whether a novel algorithm that analyzes pre-extraction computed tomographic (CT) images can determine the likelihood and location of lead-lead interactions and lead-vessel attachment within patients' venous vasculatures. This information can be used to identify potential case challenges in the planning stages., Methods: We developed an algorithm to estimate the presence and position of lead-lead interactions and lead-vessel adherences by tracking distance between the leads and distance between the lead and superior vena cava in a sample of 12 patients referred to the United Heart and Vascular Clinic for lead extractions due to infection (n = 5), lead failure (n = 5), and tricuspid regurgitation (n = 2)., Results: Preliminary results indicate that the developed algorithm successfully identified lead-lead and lead-vascular attachments compared to review of CT images by medical experts., Conclusion: With future validation and clinical implementation, this algorithm could aid physician preparedness by minimizing intraprocedural emergencies and may improve patient outcomes., (Copyright © 2020 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Lead extraction procedures have a low but real risk of major complications, such as superior vena cava tear and cardiac tamponade. Complications during lead removal are commonly related to lead binding sites, lead malposition, and lead perforation. Lead extraction imaging may indicate lead vascular binding sites, lead position, and perforation. Several imaging modalities are available, including chest radiograph, cardiac computed tomography, and echocardiography. The information provided by various imaging modalities will help assess the challenges of each lead extraction procedure and allows for better preprocedure planning., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Background: Electrical heterogeneity (EH) during cardiac resynchronization therapy may vary with different left ventricular (LV) pacing sites., Objective: The purpose of this study was to evaluate the relationship between such changes and acute hemodynamic response (AHR)., Methods: Two EH metrics-standard deviation of activation times and mean left thorax activation times-were computed from isochronal maps based on 53-electrode body surface mapping during baseline AAI pacing and biventricular (BiV) pacing from different pacing sites in coronary veins in 40 cardiac resynchronization therapy-indicated patients. AHR at different sites was evaluated by invasive measurement of LV-dp/dt max at baseline and BiV pacing, along with right ventricular (RV)-LV sensing delays and QRS duration., Results: The site with the greatest combined reduction in standard deviation of activation times and left thorax activation times from baseline to BiV pacing was hemodynamically optimal (defined by AHR equal to, or within 5% of, the largest dp/dt response) in 35 of 40 patients (88%). Sites with the longest RV-LV and narrowest paced QRS were hemodynamically optimal in 26 of 40 patients (65%) and 28 of 40 patients (70%), respectively. EH metrics from isochronal maps had much better accuracy (sensitivity 90%, specificity 80%) for identifying hemodynamically responsive sites (∆LV dp/dt max ≥10%) compared with RV-LV delay (69%, 85%) or paced QRS reduction (52%, 76%). Multivariate prediction model based on EH metrics showed significant correlation (R 2 = 0.53, P <.001) between predicted and measured AHR., Conclusion: Changes in EH from baseline to BiV pacing more accurately identified hemodynamically optimal sites than RV-LV delays or paced QRS shortening. Optimization of LV lead location by minimizing EH during BiV pacing, based on body surface mapping, may improve CRT response., (Copyright © 2016 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

The most common arrhythmias associated with inferior-wall and anterior-wall myocardial infarction are bradycardia and supraventricular and ventricular tachycardia. Optimal treatment approaches are based on the pathophysiology of the infarct and the presence of contributing medical factors (eg, congestive heart failure, metabolic disorders). Temporary or permanent pacemaker therapy is helpful in some patients. Sudden death due to arrhythmia after myocardial infarction may be predicted and avoided in certain situations.

This study evaluated the relation between patency of the infarct-related artery and the presence of late potentials on the signal-averaged electrocardiogram (ECG) in 124 consecutive patients (98 men, 26 women; mean age 59 years) with acute myocardial infarction receiving thrombolytic therapy, acute percutaneous transluminal coronary angioplasty or standard care. All patients were studied by coronary angiography, measurement of ejection fraction and signal-averaged ECG. The infarct-related artery was closed in 51 patients and open in 73. Among patients with no prior myocardial infarction undergoing early attempted reperfusion therapy, a patent artery was associated with a decreased incidence of late potentials (20% versus 71%; no significant difference in ejection fraction). In the 48 patients receiving thrombolytic agents within 4 h of symptom onset, the incidence of late potentials was 24% and 83% among patients with an open or closed artery, respectively (p less than 0.04). The most powerful predictors of late potentials were the presence of a closed infarct-related artery, followed by prior infarction and patient age. Among patients receiving thrombolytic agents within 4 h of symptom onset, the only variable that was predictive of the presence of late potentials was a closed infarct-related artery. These data imply that reperfusion of an infarct-related artery has a beneficial effect on the electrophysiologic substrate for serious ventricular arrhythmias that is independent of change in left ventricular ejection fraction as an index of infarct size. These findings might explain, in part, the low late mortality rate in survivors of myocardial infarction with documented reperfusion of the infarct-related artery.

This study evaluated the recovery after exercise of both ST-segment depression on the exercise electrocardiogram (electrical evidence of ischemia) and exercise-induced abnormalities in wall motion or ejection fraction as detected by radionuclide angiography. The study group of 31 patients was selected to undergo prolonged electrocardiographic and radionuclide imaging after exercise because they had persistent ST-segment depression greater than 3 minutes after exercise and radionuclide angiographic evidence of ischemia at peak exercise. In 27 (87%) of the 31 patients, radionuclide evidence of ischemia recovered more quickly than the electrocardiogram. Only 15 of the 31 patients had exercise-induced radionuclide abnormalities after exercise. Compared with the 16 patients without such findings of ischemia after exercise, these 15 patients had a worse wall motion score at peak exercise (5.3 vs 3.9; p less than 0.01) and a smaller increase in systolic blood pressure with exercise (p less than 0.05) and after exercise (p less than 0.01). Radionuclide angiographic evidence of ischemia recovers more quickly after exercise than ST-segment depression. When there is radionuclide evidence of ischemia after exercise, it is associated with more severe ischemia during exercise.

One hundred ten patients with asymptomatic nonsustained ventricular tachycardia (VT) were evaluated prospectively to assess the value of electrophysiologic testing. This testing consisted of up to 3 extrastimuli delivered during 3 drive cycle lengths from 2 right ventricular sites. A positive study was defined as monomorphic VT lasting 30 seconds or requiring cardioversion. Patients with a positive study were treated, and serial drug testing was done. An event during follow-up was sustained VT or cardiac arrest. The mean follow-up was 15 months. Of 57 patients with an ejection fraction greater than or equal to 40%, 6 had a positive electrophysiologic test with 1 event and 51 had a negative test with 1 event. Twenty-eight patients had an ejection fraction less than 40% and coronary artery disease: 14 had a positive test with 1 event, and 14 had a negative test with 3 events. Twenty-five patients had an ejection fraction less than 40% and no coronary artery disease: 1 had a positive test with no events, and 24 had a negative test with 8 events. Only ejection fraction and congestive heart failure class were found to be independent predictors of outcome. Patients with an ejection fraction greater than 40% had low inducibility (11%), had few events (3.5%) and did not require electrophysiologic testing. In patients with an ejection fraction less than 40% and coronary artery disease, inducibility was high (50%) and a negative study was of no value. Patients with an ejection fraction less than 40% and no coronary artery disease had low inducibility (4%), had frequent events (33%) and did not benefit from electrophysiologic testing.

To improve the predictive accuracy of the signal-averaged electrocardiogram, we created a linear logistic model for predicting ventricular tachycardia during electrophysiologic testing. This signal-averaged electrocardiographic model was created from data obtained from 214 patients undergoing electrophysiologic testing (70 had ventricular tachycardia during electrophysiologic testing) by using stepwise logistic regression to rank eight clinical and nine signal-averaged electrocardiographic variables. The best predictors were ejection fraction, history of infarction, ventricular ectopic pairs or nonsustained ventricular tachycardia on Holter monitoring, QRS duration after 25-Hz filtering, and root mean square voltage of the terminal 40 msec of the QRS complex after 40- and 80-Hz filtering. Cross validation (a statistical technique that can be used to accurately evaluate how a predictive model will perform on a prospective patient population) was used to validate the model. After cross validation, the model's sensitivity was 91% and specificity was 59% for predicting ventricular tachycardia during electrophysiologic testing. This model compared favorably with established 25-Hz late-potential criteria (QRS duration of more than 110 msec and root mean square voltage of less than 25 microV of the terminal 40 msec of the QRS complex; sensitivity, 64%; specificity, 85%) and with established 40-Hz late-potential criteria (QRS duration of more than 114 msec or root mean square voltage of less than 20 microV of the terminal 40 msec of the QRS complex or duration of the low-amplitude signal less than 40 microV at the terminal QRS complex that is greater than 38 msec; sensitivity, 84%; specificity, 54%).(ABSTRACT TRUNCATED AT 250 WORDS)

Signal-averaged electrocardiography (ECG) is a new noninvasive test for identifying patients at risk for ventricular arrhythmias. This computerized method of analyzing standard ECGs identifies particular microvolt-level signals called late potentials. Late potentials have been correlated with clinical ventricular tachycardia, are predictive of ventricular tachycardia inducibility at the time of electrophysiologic testing, and are predictive of arrhythmic events after myocardial infarction. In this review, we describe late potentials, the method of obtaining and processing the signal-averaged ECG, and clinical studies in various patient groups that have assessed the predictive value of the signal-averaged ECG for identification of patients at risk for subsequent ventricular arrhythmias.

Between 1961 and 1984, 91 patients underwent simultaneous triple valve replacement at the Mayo Clinic. Of the 273 prosthetic valves used, 77% were Starr-Edwards. Perioperative (30 day) mortality was 24% to 27% between 1962 and 1974 and 7% between 1975 and 1983 (p = .17). In patients with NYHA class IV symptoms, perioperative mortality was 44%, and in those with milder symptoms, it was 8% (p less than .0001). The median follow-up was 7.5 years (range, 6 weeks to 20 years). Cumulative survival, which was calculated taking into consideration perioperative mortality, was 64% at 1 year, 55% at 5 years, 40% at 10 years, and 25% at 15 years. Multivariate analysis identified preoperative functional class and age as predictors of late survival. Among causes of late mortality were sudden death in 32.5%, congestive heart failure in 15%, thromboembolism in 12.5%, prosthetic valve dysfunction in 7.5%, and infective endocarditis in 5%. Late complications included systemic emboli in 42% (embolic rate, 12.3 events per 100 patient-years), bleeding in 22%, myocardial infarction in 16%, and infective endocarditis in 6%. Eight patients required reoperation for prosthetic valve dysfunction, and 12 patients had permanent pacemakers. Of the 29 patients still alive, 79% are in NYHA class I or II. In summary, perioperative mortality after triple valve replacement appears to be declining; long-term survival in 30 day survivors is similar to that after single valve replacement and excellent symptomatic improvement can be obtained, although morbidity is high.

DDD pacemakers offer a physiologic form of pacing for selected patients by incorporating atrioventricular synchrony over a wide range of atrial rates. Selection of a patient for DDD pacing necessitates a thorough knowledge of the individual functions of the DDD pacemaker, the limitations of DDD pacing, and the patient's own electrical and physiologic needs. Continuing developments in cardiac pacing include further reduction of the possibility of pacemaker-mediated tachycardia, increased matching to metabolic needs, and advancement of telemetric technology and electrophysiologic testing.

Signal averaging reduces noise in the surface ECG, allowing late potential identification. However, late potentials may vary within a patient from study to study. In a population with stable biopotentials, this work evaluated how residual noise (RN) affects signal-averaged ECG (SA-ECG) reproducibility.

The signal-averaged ECG has proven to be a valuable tool for identifying patients at risk of ventricular arrhythmias. This computerized method of analyzing standard ECGs identifies microvolt-level late potentials that represent delayed conduction through diseased myocardium. This diseased myocardium is a potential substrate for reentrant ventricular arrhythmias. In select patient groups, the signal-averaged ECG predicts electrophysiologic testing results. Problems remain and continued development is needed to evaluate patients with conduction system disease, the patient without coronary artery disease but at risk of sudden death, and proper general application of the technique.

We describe 3 patients who presented with severe cardiac disability as a result of tricuspid insufficiency, in the setting of severe coronary disease. Pertinent physical findings were signs of right heart failure, a tricuspid regurgitant murmur, and absence of left heart failure. Echocardiography and subsequent cardiac catheterization demonstrated significant tricuspid insufficiency, dilated right ventricle, impairment of right ventricular function, and preserved left ventricular function. Two patients were treated successfully with DeVega annuloplasty. Symptomatic tricuspid insufficiency can be seen in the setting of coronary artery disease and, when left ventricular function is well preserved, surgical correction is feasible.