Bradycardiac Angina: Haemodynamic Aspects and Treatment

A patient with a sinus bradycardia and angina is described who was unable to increase his heart rate on vigorous exercise by more than a few beats. His severe angina was attributed to the bradycardia. Atrial pacing of his heart abolished his angina and increased his exercise tolerance. Circulatory changes at rest, on exertion, and with atrial pacing are described. The cause of angina in this patient is discussed.     

An unusual cause of recurrent syncope in a patient with implantable cardioverter defibrillator

Electromagnetic interferences (EMI) deriving from electrical devices may affect implantable cardioverter defibrillators (ICD). Improved algorithms have been developed in order to minimize adverse effects. However, caution should be still recommended in ICD recipients when handling electrical devices. Here we describe the case of an ICD patient with recurrent syncopal episodes due to inhibition of pacing by oversensing of electrical noise from a not properly grounded washing machine.     

Transvenous implantation of a ventricular pacing lead in a patient with an artificial tricuspid valve prosthesis

The preference for treatment of symptomatic bradycardia is transvenous right ventricular pacing combined with atrial synchronisation if applicable. In the case of congenital anomalies where no conduit is present between the peripheral veins and the right ventricle, it is not possible to place the ventricular pacing lead in the right ventricle. Also the presence of an artificial valve in the tricuspid position excludes placement of an endocardial right ventricular pacing lead. Since the introduction of biventricular pacing, new guiding catheters and leads used as a transvenous route for left ventricular pacing are available. We report implantation of a ventricular pacing lead in the great cardiac vein for permanent ventricular pacing in a patient with a tricuspid valve prosthesis.     

ICD discrimination of SVT versus VT with 1:1 V-A conduction: A review of the literature

Inappropriate ICD shocks are associated with increased mortality. They also impair patients'' quality of life, increase hospitalizations, and raise health-care costs. Nearly 80% of inappropriate ICD shocks are caused by supraventricular tachycardia. Here we report the case of a patient who received a single-lead dual-chamber sensing ICD for primary prevention of sudden cardiac death and experienced inappropriate ICD shocks. V-A time, electrogram morphology, and response to antitachycardia pacing suggested atrioventricular nodal reentry tachycardia, which was confirmed in an electrophysiology study. Inspired by this case, we performed a literature review to discuss mechanisms for discrimination of supraventricular tachycardia with 1:1 A:V relationship from ventricular tachycardia with 1:1 retrograde conduction.     

T-wave Oversensing with Inappropriate Therapy in Remote Monitoring

T-wave oversensing can cause inappropriate implantable cardioverter-defibrillator (ICD) therapies that are difficult to correct. Remote monitoring allows follow-up of ICD patients without visiting the hospital and can help in early detection of any malfunctions. We describe the case of a patient who experienced inappropriate antitachycardia pacing therapy due to T-wave oversensing; the problem was promptly detected by remote monitoring and corrected by device reprogramming.     

Intrinsic anti-tachycardia pacing terminated ventricular tachycardia resistant to traditional anti-tachycardia pacing

Implantable cardioverter-defibrillators (ICDs) serve to reduce the risk of sudden death; however, ICD shocks worsen patient prognosis. Therefore, attempts have been made to terminate life-threatening arrhythmias without ICD shocks. A 71-year-old man with non-ischemic cardiomyopathy, who previously underwent cardiac resynchronization therapy-defibrillator (CRT-D) placement, was hospitalized for ventricular tachyarrhythmia (VT) that was refractory to traditional anti-tachycardia pacing (ATP). Endocardial and epicardial ablation failed to prevent VT recurrence. Since the CRT-D battery was exhausted, it was replaced with a Cobalt? XT HF CRT-D (Medtronic, Minneapolis, MN, USA), and the intrinsic ATP (iATP) algorithm was employed. Although VT recurred frequently, recurrent VTs were terminated by the iATP, which created a conduction block in the circuit without VT acceleration or shock. This is the first reported case wherein an iATP algorithm was effective against VT resistant to traditional anti-tachycardia pacing. This novel ATP algorithm has the potential to terminate refractory VT without ICD shocks and provide a better prognosis.     

The effects of right ventricular apical pacing on left ventricular function. Stimulation of the right ventricular apex: should it still be the gold standard?

Current pacing practice is undergoing continuous and substantial changes. Initially pacing had an exclusively palliative role, since it was reserved for patients developing complete heart block or severe symptomatic bradycardia. With the appearance of novel pacing indications such as pacing for heart failure and atrial fibrillation, the effect of pacing site on cardiac function has become a critically important issue and a subject for consideration. It seems that the classical pacing site in the right ventricular apex is no longer the gold standard because of possible disadvantageous effects on cardiac function. The aim of this review article is to discuss the effect of right ventricular apical pacing on cardiac function including cellular and hemodynamic changes. We also aim to discuss the role of alternative pacing sites in the light of cardiac function.     

Single site pacing through the anterior interventricular vein in a patient with a mechanic tricuspid valve

Transvenous endocardial pacing through classical implantation of a pace/sensing lead in the right ventricle is strictly contraindicated in patients with a mechanical tricuspid valve. Usually permanent pacing is achieved by an epimyocardial surgical approach. We hereby describe the implantation of a single site left ventricle pacing lead in the anterior interventricular vein in a 60 year-old woman with symptomatic bradycardia, permanent atrial fibrillation, and mechanical tricuspid valve. The described use of left ventricle pacing through a coronary vein lead, in a patient with favorable venous anatomy, provided (through a minimal invasive approach) effective with a low and stable threshold.     

Normal pacing function with normal impedance trends despite evident lead fracture in an implantable defibrillator – What is the mechanism?

A 63-year-old lady with a high-grade atrioventricular (AV) block and a structurally normal heart underwent permanent pacemaker implantation (dual chamber, Medtronic Ltd) 8 years back. On follow up, she had a recurrence of syncope after 3 years. The device interrogation at that time had revealed ventricular tachycardia (VT) for which she underwent implantable cardioverter defibrillator (ICD, Medtronic Ltd, Egida DR, DF1) upgradation at another center (electrograms not available). Now, she presents with episodes of presyncope after another 5 years. The Echocardiography was unremarkable. The ICD was interrogated & there was a stored ventricular fibrillation (VF) episode. But the electrograms suggested noise over a true VF electrogram noted in both near and far-field. In all probability, the VF was not a true one which might have arisen from some lead noise or from an electromagnetic interference (EMI). Fluoroscopy revealed an evident lead fracture near the superior vena cava (SVC) coil. The stored electrogram (EGM) characteristics also suggested possible lead noise rather than a true VF. She was advised for lead revision. Interestingly, all pacing parameters were normal along with normal impedance despite the evident lead fracture. This happened due to the ICD lead arrangements as there are separate electrodes for the SVC/RV coil and pacing. While the SVC coil was damaged, the pacing electrodes remained unaffected. Since the patient has no episode of true VT/NSVT and the echocardiography was normal, she was managed temporarily by changing the pacemaker to asynchronous (DOO) mode.     

A fortuitous syncope. The pitfalls of integrated bipolar defibrillator leads

Myopotential oversensing in implantable defibrillators causing inhibition of pacing and inappropriate therapies is well described. Current literature is dominated by reports of diaphragmatic muscle as the source of such far-field oversensing. Those reporting pectoral muscle sources were invariably due to unipolar sensing circuits, incorrect DF-1 connections or inappropriate programming. We report an interesting case of pectoral muscle myopotential oversensing causing inhibition of bradycardia pacing leading to presyncope and syncope.     

Pediatric SubQ-ICD implantation,a single center review of the inter-muscular technique

IntroductionPediatric patients with cardiomyopathies are at risk for sudden death and may need implantable cardioverter defibrillators (ICD’s), but given their small size and duration of use, children are at increased risk for complications associated with ICD use. The subcutaneous ICD presents a favorable option for children without pacing indications. Unfortunately, initial pediatric studies have demonstrated a high complication rate, likely due to the 3-incision technique employed.Material and methodsPatients with ICD but no pacing indication were retrospectively reviewed after implantation of subcutaneous ICD via the two-incision technique. In half of the patients, 10-J impedance test was also performed to compare with impedance obtained after defibrillation threshold testing with 65-J.ResultsTwelve patients were included. The median age was 14 years (range 10–16 years) with eight males included (72.7%). The median weight was 55 kg (range 29 kg–75.1 kg). Follow-up had a median of 11.5 months (range 2–27 months). The median body mass index was 18.4 kg/m squared (range 15.5–27.9 kg/m squared). One patient suffered a minor complication after tearing off the incisional adhesive strips early and required a non-invasive repair in clinic. Shock impedance had a median of 55 J (range 48–68 J). There was one appropriate shock/charge and no inappropriate shocks during follow-up.ConclusionThe two-incision, intermuscular technique appears to have a lower acute complication rate than prior reports, in our cohort of 12 pediatric patients.     

A trial design for evaluation of empiric programming of implantable cardioverter defibrillators to improve patient management

The delivery of implantable cardioverter defibrillator (ICD) therapy is sophisticated and requires the programming of over 100 settings. Physicians tailor these settings with the intention of optimizing ICD therapeutic efficacy, but the usefulness of this approach has not been studied and is unknown. Empiric programming of settings such as anti-tachycardia pacing (ATP) has been demonstrated to be effective, but an empiric approach to programming all VT/VF detection and therapy settings has not been studied. A single standardized empiric programming regimen was developed based on key strategies with the intention of restricting shock delivery to circumstances when it is the only effective and appropriate therapy. The EMPIRIC trial is a worldwide, multi-center, prospective, one-to-one randomized comparison of empiric to physician tailored programming for VT/VF detection and therapy in a broad group of about 900 dual chamber ICD patients. The trial will provide a better understanding of how particular programming strategies impact the quantity of shocks delivered and facilitate optimization of complex ICD programming.     

Efficacy of empirical cardiac pacing in syncope of unknown cause.

Cardiac pacing is often considered in patients with recurrent syncope after repeated attempts to document the cause have failed. To assess the results of this tactic we reviewed the records of 104 patients who had received pacemakers for known or suspected bradycardia between September 1973 and March 1985. The patients were classified retrospectively into three groups: group 1 (31 patients with a mean age of 73 years) had unequivocal documentation of bradycardia during syncope, group 2 (42 patients with a mean age of 71 years) had electrocardiographic or electrophysiologic evidence of potential bradycardia but no documentation during spontaneous syncope, and group 3 (31 patients with a mean age of 69 years) had a history "suggestive of" bradycardia-related syncope but no other evidence to support the diagnosis. The rates of recurrence of syncope during follow-up were 6.3%, 7.3% and 32.2% in groups 1, 2 and 3 respectively (p less than 0.01). In group 3 recurrence was more probable in patients with loss of consciousness for more than 2 minutes than in those who were unconscious for 2 minutes or less (p less than 0.05). The results suggest that pacemaker implantation is justified for recurrent syncope after extensive attempts to document a spell have failed if abnormal diagnostic test results suggest bradycardia as a possible cause. Empirical pacing is less satisfactory in patients with normal results of evaluation but may arguably be justified when patients have recurrent syncope with injury.     

Placement Of A Coronary Sinus Pacing Lead From A Sub-occluded Left Subclavian Vein Using A Collateral Vein To The Right Subclavian Vein

Upgrading of a pacing system in the presence of a subclavian occlusion is technically challenging. We describe the case of a patient who underwent a successful upgrading procedure of an implantable cardioverter-defibrillator (ICD) to a biventricular defibrillator (ICD-CRT) in the presence of a suboccluded left subclavian vein, using a collateral vein that drained into the contralateral subclavian vein.     

State of the art of ICD programming: Lessons learned and future directions

The lifesaving benefits of implantable cardioverter defibrillator (ICD) therapy are more and more weighted against possible harm (e.g. unnecessary device therapy, procedural complications, device malfunction etc.) which might have adverse effects on patients’ perceived health status and quality of life. Hence, there has been an increasing interest in the optimisation of ICD programming to prevent inappropriate and appropriate but unnecessary device therapy. The purpose of the current report is to give an overview of research into the optimisation of ICD programming and present the design of the on-going ENHANCED-ICD study. The ENHANCED-ICD study is a prospective, safety monitoring study enrolling 60 primary and secondary prophylactic ICD patients at the University Medical Center Utrecht. Patients implanted with any type of ICD with SmartShock technology^TM, and between 18–80 years of age, were eligible to participate. In all patients a prolonged detection of 60/80 intervals was programmed. The primary objective of the study is to investigate whether enhanced programming to further reduce ICD therapies is safe. The secondary objective is to examine the impact of enhanced programming on (i) antitachycardia pacing and shocks (both appropriate and inappropriate) and (ii) quality of life and distress. The first results of the ENHANCED-ICD study are expected in 2015.     

Left and Right Ventricle Leads Switch as a Solution for T Wave Oversensing - How a Good Idea Turned Out Bad

A 50-year-old male with a CRT defibrillator received inappropriate ICD shocks due to T-wave oversensing. Decreasing the sensitivity to avoid T wave oversensing was not an option due to a suboptimal R-wave sensing amplitude. We decided to re-plug the LV lead in the RV port and the RV lead in the LV port. This however led to intermittent phrenic nerve stimulation due to mandatory bipolar (tip-ring) or unipolar (tip-can) pacing on the LV-lead from the RV port. Re-intervention was necessary with the implantation of an additional pacing/sensing RV lead. A software programmable choice to switch sensing and tachycardia detection from RV to LV lead could be a valuable feature in future CRT devices.     

Atrial Pacing to Control Heart Rate and Rhythm in Acute Cardiac Conditions

Increasing the heart rate by a bedside atrial pacing technique was successfully utilized to treat serious cardiac arrhythmia or failure in 13 patients. Nine of these had ventricular arrhythmia refractory to drugs. Seven had evidence of sinus node depression or disease since their sinus pacemaker was below 70 beats per minute under decompensated conditions. In five, coronary artery disease was associated with the bradycardia and in two, digitalis toxicity was related to depression of the intrinsic pacemaker rate. Two patients in the coronary group required implantation of a permanent demand ventricular pacemaker. Hemodynamic studies were performed in seven patients. Only one patient had no increase in cardiac output with pacing rates above his resting rate. The other six patients showed an increase in cardiac output from 22 to 81% at paced rates between 70 and 125/minute. The duration of pacing ranged from one hour to 14 days and averaged five days.     

Initial experience,feasibility and safety of permanent left bundle branch pacing: results from a prospective single-centre study

BackgroundLeft bundle branch (LBB) pacing is a novel pacing technique which may serve as an alternative to both right ventricular pacing for symptomatic bradycardia and cardiac resynchronisation therapy (CRT). A substantial amount of data is reported by relatively few, highly experienced centres. This study describes the first experience of LBB pacing in a high-volume device centre.MethodsSuccess rates (i.e. the ability to achieve LBB pacing), electrophysiological parameters and complications at implant and up to 6 months of follow-up were prospectively assessed in 100 consecutive patients referred for various pacing indications.ResultsThe mean age was 71 ± 11 years and 65% were male. Primary pacing indication was atrioventricular (AV) block in 40%, CRT in 42%, and sinus node dysfunction or refractory atrial fibrillation prior to AV node ablation in 9% each. Baseline left ventricular ejection fraction was < 50% in 57% of patients, mean baseline QRS duration 145 ± 34 ms. Overall LBB pacing was successful in 83 of 100 (83%) patients but tended to be lower in patients with CRT pacing indication (69%, p = ns). Mean left ventricular activation time (LVAT) during LBB pacing was 81 ms and paced QRS duration was 120 ± 19 ms. LBB capture threshold and R‑wave sense at implant was 0.74 ± 0.4 mV at 0.4 ms and 11.9 ± 5.9 V and remained stable at 6‑month follow-up. No complications occurred during implant or follow-up.ConclusionLBB pacing for bradycardia pacing and resynchronisation therapy can be easily adopted by experienced implanters, with favourable success rates and safety profile.     

Usefulness of a lead delivery system consisting of a fixed-shaped sheath and a lumenless bipolar lead in a patient with absent right and persistent left superior vena cava: A case report

We report the case of an 84-year-old female with symptomatic bradycardia due to a complete atrioventricular block, who carried absent right and persistent left superior vena cava (SVC). Implantation of a pacing lead, particularly within the right ventricle (RV) in a patient with this venous anomaly is accompanied by technical difficulties. However, the apparatus consisting of a fixed-curve sheath (Model C315-S10, Medtronic, Inc., Minneapolis, MN, USA) and a lumenless fixed-screw pacing lead (Model 3830, Medtronic), allowed a rapid delivery into the RV without any complications. By rotating the Model C315-S10 sheath in the counterclockwise direction in the right atrium, its tip faced the tricuspid orifice, advanced across the tricuspid valve and confronted the RV lower septum near the apex. Then the RV-lead was fixed with acceptable pacing and sensing parameters. Utilizing a lumenless pacing lead and a preformed sheath to deliver it is a novel approach that could be helpful in pacemaker implantation in patients with absent right and persistent left SVC.     

Motion energy as a control variable for adapting stimulation frequency

An activity sensing rate-responsive pacing system is presented which adaptively controls heart rate to adjust cardiac output in response to increased metabolic demand, and more optimally restore homeostasis of the intact cardiovascular system. The current use of ventricular demand and DDD universal pacing systems, although rate and multi-parameter and multi-function programmable, are fixed at these programmed settings. These devices are adequate for patients at rest or during moderate exertion, but are suboptimal for physically active patients whose physiology requires increased oxygen supply to meet an increased cardiac demand. In the past, these patients may have experienced fatigue or dyspnea out of proportion to their cardiovascular disease. The Ergos rate-adaptive single- and dual-chamber pacing system is a second generation pulse generator which is rate responsive to a patient's increased physiologic demand by sensing a motion signal which reflects increased work load and the need for a compensating increase in heart rate. Ergos offers increased assistance to patients with sinus bradycardia who may require the rate-responsiveness with the additional advantage of AV synchrony. Clinical results show the effectiveness of the presented sensor control by motion energy for rate adaptive pacing therapy.