Leadless pacing.

Leadless self-contained intracardiac pacemakers were developed with the aim of abolishing the short- and long-term risk of lead- and pocket-related complications associated with transvenous devices. Leadless pacemakers promise minimally invasive procedures, long battery lives, and small amounts of foreign materials in the body. Experiences with the pioneering single-chamber devices have provided reasons for optimism about the future of the leadless concept. In the future, as more patients receive and live longer with implantable devices, the total risk of procedure- and lead-related complications is expected to increase, adding a sense of urgency to the need for leadless alternatives to transvenous pacemakers. This review surveys the performance of currently available leadless pacemakers as well as emerging new innovative adaptations and applications of the leadless concept.

[An outpatient education program for patients and partners after implantation of implantable cardioverter defibrillators (ICD)]. / Ein ambulantes Schulungsprogramm für Betroffene und Partner nach Erstimplantation eines implantierten Kardioverter/Defibrillators (ICD).

BACKGROUND: The implantation of an implantable cardioverter defibrillator (ICD) is commonly followed by a physical and psychological process of adaptation to the new situation. Psychological support is often not provided and patients are left alone with questions and their needs. Because of the emerging sense of support group programs have proven to be apt for clearing up questions and addressing personal concerns. In the present study a psychoeducational program is presented and evaluated in detail. MATERIAL AND METHODS: A total of 308 patients with ICDs as well as their partners participated in a 2 day psychoeducational program. Of the patients 100 as well as their partners were asked to complete questionnaires concerning anxiety and depression (HADS) as well as their satisfaction with the program. The program consists of five modules: a warm up and getting to know each other; medical and technical information concerning the ICD, psychoeducation concerning the topics anxiety and avoidance, relaxation and an experience report of a patient who has had an ICD for many years. RESULTS: The evaluation results of 72 participants are present. All patients would definitively recommend participation in the program to other patients with an ICD without restrictions. The satisfaction with the five different modules of the intervention was very high. The depression as well as the anxious symptomatology in the HADS decreased significantly in the 1 year follow-up but did not exceed the cut-off point of 8. The anxiety and depression symptoms of the partners decreased significantly and exceeded the cut-off point of 8 in the follow-up.

[Psychocardiological practice guidelines for ICD implantation and long-term care]. / Psychokardiologischer Praxisleitfaden für die ICD-Implantation und Langzeitbetreuung.

In the literature there are only very few reports on systematic education or information for patients after implantation. Research in this field has only just begun so that there are no sufficiently evaluated models which could serve as the foundations for recommendations. Approximately 80% of affected patients, relatives and partners show a good cognitive acceptance and are capable of coping with the situation. However, in the first 12 months following ICD implantation some 20% of patients are in a state of anxiety and depression. These patients must be recognized and if necessary treated and given support. For this reason it is important in the consultation and routine appointments to give patients the chance to express their views on this if necessary. Only then can cardiologists recognize whether a patient is under substantial mental stress. It is recommended that immediately after the implantation and before being discharged from hospital, a screening procedure for anxiety and depression should be carried out using, e.g. the Hospital Anxiety and Depression Scale (HADS) and to distribute a questionnaire on desired information and unanswered questions. This would not only give a lead in for a targeted consultation during the follow-up appointment in the first year but also allow the opportunity to offer such patients an education course in order to specifically approach the problem being experienced. Patients who have experienced more than 5 shocks in 12 months or more than 3 shocks in 1 episode should attend a psychocardiological consultation in order to check whether there are post-traumatic disorders. It is imperative that these be treated because they do not in general resolve spontaneously.

[Changes in depression, anxiety, and vital exhaustion in patients after ICD implantation. Comparison of clinical subgroups]. / Veränderungen bei Depression, Angst und vitaler Erschöpfung bei Patienten nach einer ICD-Implantation. Vergleich klinischer Subgruppen.

BACKGROUND: The psychological strain of an implantable cardioverter-defibrillator (ICD) is infrequently explored in prospective studies, which have until now generally focused on the dimensions anxiety and depression. Furthermore, vital exhaustion (VE; ICD10 F 48.0) is known as a very good predictor for negative outcome in patients with coronary heart disease. The influence of VE on patients with an ICD is presented and analyzed in a prospective study. METHODS: A total of 249 patients with an ICD completed a set of questionnaires (HADS, EQ-5D, VE) at baseline and at the 1-year follow-up. RESULTS: The patients with high levels of depression, anxiety, and VE after ICD implantation did not show spontaneous remission after 1 year. DISCUSSION: As expected, the implanatation of an ICD is associated with high acceptance and increased life quality in about 3/4 of patients. However, there is a subgroup of patients (20-30%) who have difficulties and the measured dimensions remain at elevated levels after implantation, thus, indicating that these patients probably need competent psychological help.

Do gender differences exist in pacemaker implantation?--results of an obligatory external quality control program.

AIMS: The aim of the study was to evaluate the effects of patient gender onto primary pacemaker implantation, evaluating the database of the Institute of Quality Assurance Hessen in the federal state of Hessen, Germany. METHODS AND RESULTS: The database of the obligatory external quality control program for the years 2003-2006 was evaluated retrospectively. In 72 centres, 17 826 patients undergoing stationary primary pacemaker implantation have been registered. Male patients had more AV blocks when compared with women and less sick sinus syndrome and atrial fibrillation with bradycardia. In patients being 80 years and older, men received significantly more dual-chamber devices than women for the indications: AV block and sick sinus syndrome. In women, atrial pacing thresholds were significantly higher and P-wave amplitudes were significantly lower. Women had, independent from age or pacing system implanted, significantly more acute complications than men, with significant differences for pneumothorax and pocket haematoma. CONCLUSION: This large-scale real-life patient cohort of primary stationary pacemaker implantation showed that gender has an impact onto pacemaker implantation, with less favourable outcomes for women.

Desynchronization: a novel model to induce heart failure.

BACKGROUND: Previous large animal heart failure models led to inhomogeneous results. Therefore, we developed a novel model combining rapid pacing with forced ventricular desynchronization. METHODS: Heart failure was induced in 20 pigs during a pacing period of 21 days. Group A (n = 10) received one right ventricular lead (220 bpm). In group B (n = 10), two leads were implanted in different right ventricular regions with beat-to-beat alternation of activation sites (each lead 110 bpm). Sham-operated pigs (n = 6) served as controls. Hemodynamics were invasively evaluated and tissue was analyzed by immunohistochemistry and zymography. RESULTS: Hemodynamics were significantly more impaired in group B with an increase of pulmonary capillary wedge and central venous pressure and a reduction of cardiac index (control 4.3 +/- 0.1 l/min/m (2); A 3.6 +/- 0.2; B 2.9 +/- 0.2, P < 0.05). Heart-to-body weight ratio was significantly higher in group B. Histological analyses showed a significant increase of cell diameters and interstitial fibrosis with significantly higher collagen contents in group B. CONCLUSION: The new model with a combination of rapid pacing and forced desynchronization of the ventricular contraction is superior to traditional heart failure models induced solely by rapid pacing.

[Ambulatory electrocardioversion of atrial fibrillation by means of biphasic versus monophasic shock delivery. A prospective randomized study]. / Ambulante Elektrokardioversion von Vorhofflimmern mittels biphasischer versus monophasischer Schockabgabe. Eine prospektiv randomisierte Studie.

Transthoracic electrical cardioversion using a monophasic waveform is the most common method converting persistent atrial fibrillation into sinus rhythm. Recently, cardioversion with a new biphasic waveform has shown promising results for treatment of atrial fibrillation. We undertook a randomized prospective trial comparing the efficacy and safety of the two waveforms for ambulatory cardioversion of atrial fibrillation. A total of 118 consecutive patients (mean age 62 years [SD 11]) presenting with persistent atrial fibrillation (mean duration 8 months [SD 11]) for ambulatory electrical cardioversion were randomized to receive either monophasic (n = 57) or biphasic shocks (n = 61). We used a standardized step-up protocol with increasing shock energies (100-360 joules) in either group. In all patients an anterior-posterior shock electrode position was used. If sinus rhythm was not achieved with the third (360 joules) shock, cardioversion was repeated with the opposite waveform. The two groups did not differ in demographic or disease-related data. The success rate was 100% for the biphasic and 73.7% for the monophasic waveform (p < 0.001). Biphasic patients required fewer shocks (1.5 versus 2.9) and a lower mean cumulative energy (203 versus 570 joules) (p < 0.001). Twelve out of 15 unsuccessfully treated monophasic patients were converted with biphasic shocks. The success rate for all 118 patients was 97.5%. No major acute complications were observed. For ambulatory transthoracic cardioversion of persistent atrial fibrillation biphasic shocks are of greater efficacy and require less energy than monophasic shocks. The procedure can be performed ambulatory and is safe regardless of shock waveform used.

[Acute hemodynamic effects of biventricular and left ventricular pacing in chronic pacemaker-dependent patients with advanced heart failure]. / Akute hämodynamische Effekte einer biventrikulären und linksventrikulären Stimulation bei Patienten mit fortgeschrittener Herzinsuffizienz unter einer chronischen Herzschrittmachertherapie.

The beneficial hemodynamic effects of cardiac resynchronization in patients with intraventricular conduction delay have been demonstrated. The potential hemodynamic effects of cardiac resynchronization to compensate the pacing-induced left ventricular conduction delay in chronically paced heart failure patients are not as well established. The aim of the study was to evaluate the acute hemodynamic effects of biventricular and left ventricular pacing in chronically paced patients with advanced heart failure. Fourteen consecutive pacemaker or defibrillator patients with permanent atrial fibrillation and AV block (11 male, 3 woman, mean age: 68 +/- 7 years) were enrolled in this study. There were 5 ischemic (36%) and 9 nonischemic (64%) patients (mean left ventricular ejection fraction: 19 +/- 5%; mean end-diastolic left ventricular diameter: 71 +/- 11 mm). In all patients a right ventricular and left ventricular (via coronary sinus) pacing lead was placed. The aortic and left ventricular hemodynamic measurements were performed using a two-channel micro-tip catheter. The measurements of the aortic pulse pressure (APP) and (dP/ dtmax) were performed during right ventricular apical pacing (RVP), left ventricular (LVP), and biventricular pacing (BVP) (70 bpm). Compared to RVP, LVP and BVP increased APP and dP/dtmax (35.8 +/- 4.2 vs 43.3 +/- 4.5 and 41.2 +/- 4 mmHg; p < 0.001) and (758 +/- 56 vs 967 +/- 60 and 961 +/- 62 mmHg/s; p < 0.001). LVP and BVP showed a comparable hemodynamic response. The hemodynamic effects were not related to the width of the paced QRS complex. Every patient showed improved hemodynamics during LVP and BVP unrelated to the underlying heart disease and to the baseline level of left ventricular dysfunction. BVP and LVP pacing acutely improve contractile left ventricular function in chronically paced patients with advanced heart failure.

Automatic capture verification in ICD lead systems using intracardiac ventricular evoked response and reduced coupling capacitance.

AIM: Intracardiac ventricular evoked-response (ER) signals detected by implanted cardioverter defibrillator (ICD) lead systems were investigated for automatic capture verification (AC). METHOD: ER signals were evaluated with an external pacing system equipped with a reduced coupling capacitance (CC=2.2 microF) in the pacing output circuit during ventricular step-down threshold testing at 0.4 ms pulse duration. Real-time pacing markers, surface ECG and intracardiac electrograms pre- and post-filtering were digitally recorded. RESULTS: Twenty consecutive patients, age 61+/-12 years, with leads from two different manufacturers were tested - 10 were implanted with acute leads (AL) and 10 with chronic leads (CL). The analysis was based on the ER amplitude during capture and on the ER-to-afterpotential ratio (SAR), with SAR>2 as the criterion for successful capture detection. ER amplitudes (median and range) were 8.1 mV (2.1-19.5 mV) for AL and 8.3 mV (3.7-14.2 mV) for CL. SAR values (median and range) were 48.0 (2.5-682.6) for AL and 13.2 (6.3-35.9) for CL, indicating that AC could successfully be applied in all patients. CONCLUSIONS: Reducing the pacing CC allows adequate ER detection for automatic capture verification on non-selected ICD lead systems. The effect of high-voltage shock treatment on ER signal detection requires further investigation.

Diagnostic value of onset-recordings and marker annotations in dual chamber pacemaker stored electrograms.

AIMS: Stored electrograms (EGM) have recently been introduced into pacemaker therapy. New generation devices offer the possibility to store the onset of the EGM (several seconds preceding storage trigger) and marker annotations. The aim of the study was to evaluate whether the diagnostic capabilities of EGMs are improved by these new features. METHODS: We studied 65 patients (age 68+/-12 years, 41 male) implanted with a DDDR-system (PulsarMax II 1280; Guidant). During a 1-month period 319 EGMs have been recorded. EGM triggers were: Ventricular Tachycardia (VT), Non-Sustained VT (NSVT), Atrial Tachycardia Response (ATR), Pacemaker Mediated Tachycardia (PMT) and Sudden Bradycardia Response (SBR). First, each EGM was analysed with onset and markers blinded. EGMs were classified with respect to their trigger as confirmed, not-confirmed or false-positive. Analysis was then repeated with markers visible but without onset, and thereafter vice versa. Finally, EGMs were analysed with both features. It was noted whether the presence of marker annotations and/or onset-recording changed the initial classification of the stored EGMs. RESULTS: 169 EGMs were triggered by SBR, which can only be confirmed with onset recording. False positive EGMs (atrial undersensing) occurred in 12%. The remaining 150 EGMs were triggered by ATR (80%), NSVT (11%), VT (6%) and by PMT (3%). Without onset/markers 37 of these 150 EGMs (25%) could not be confirmed. With markers and onset 33/37 (89%) of these EGMs could now be classified as confirmed or false positive. These EGMs became diagnostic with onset alone in 24%, with markers alone in 24%, and with the combination of both in 41%. In 4 EGMs no definite diagnosis could be established. CONCLUSION: Stored electrograms provide direct insights into device function, thereby providing a validation of diagnostic data. The expanded recording of onset and markers results in markedly improved diagnostic capabilities - compared with conventional EGMs. These new features were necessary to interpret correctly 61% of all stored electrograms, without which a diagnosis would not have been possible. Both onset-recording and marker annotation are necessary for optimal analysis.

Comparison of generic health survey SF-36 and arrhythmia related symptom severity check list in relation to post-therapy AF recurrence.

AIM: The effect of applied therapy on quality of life (QoL) in patients with atrial fibrillation (AF) was investigated in recent studies. However, no information on clinical relevance of QoL assessing instruments in relation to post-ablation recurrence of AF is currently available. The aim of this study was to evaluate the clinical relevance of SF-36 and Arrhythmia Related Symptom Severity Check List (SSCL) to post-procedure AF recurrences in patients with paroxysmal AF undergoing pulmonary vein isolation (PVI). METHODS AND RESULTS: Sixty consecutive patients with AF were enroled in the study. The QoL was measured using SF-36 scale and SSCL. The questionnaires were administered at baseline then 3, 6, 9 and 12 months after the procedure. In order to define statistical power in relation to AF recurrence the scores were dichotomized. Positive and negative predictive accuracy (PPA, NPA) and test efficiency (sum of PPA and NPA) were calculated. Twenty-one out of 60 patients experienced a total of 66 recurrences of AF during follow-up. The parameters of SF-36 provided maximum test efficiency of 1.36, whereas the test efficiency of SSCL was 1.79. CONCLUSION: We conclude that SSCL is more specific instrument for a measurement of PVI success or failure.

[Cooled tip ablation of left ventricular outflow tract tachycardia through the aortic sinus of valsalva]. / Gekühlte HF-Stromkatheterablation epikardialer Ausflusstrakttachykardien über die Sinus valsalvae der Aorta.

BACKGROUND: Monomorphic tachycardia with an epicardial site of the arrhythmic focus in the left ventricular outflow tract (LVOT) usually cannot be ablated by an endocardial approach. We describe the use of cooled tip catheter ablation through the aortic sinus of valsalva to treat LVOT tachycardia. METHODS: In seven patients (four males, one with valvular cardiomyopathy, six patients without heart disease) with sustained and non-sustained ventricular tachycardia (VT) an epicardial focus of LVOT tachycardia could be identified by pace-mapping and earliest local activation within the aortic sinus of valsalva. Coronary angiography served to define the position of the coronary arteries with respect to the ablation catheter. High frequency current was delivered using a closed-loop cooled tip catheter system (Chilli Cool(R), Boston Scientific). ECG, Holter-ECG, echocardiography and transesophageal echocardiography were performed after the procedure and 3 months later. RESULTS: Foci were located in the left (two patients), in the right (three) and in the a coronary aortic sinus (two). Successful ablation could be achieved in six patients. No procedure-related complications could be observed during a mean follow-up of 4.2 months. CONCLUSION: Monomorphic VT with epicardial origin in the LVOT can be successfully treated by cooled tip ablation through the aortic sinus of valsalva. The use of a cooled tip ablation system may be favourable in several ways: 1) it allows the creation of deep lesions necessary to reach remote foci; 2) due to lower temperatures at the catheter/tissue interface surface tissue damage may be reduced; 3) lower catheter temperature may additionally reduce the risk of local clot formation which is crucial for all left-sided procedures and especially for ablation in the sinus of valsalva.

Inappropriate arrhythmia detection in implantable defibrillator therapy due to oversensing of diaphragmatic myopotentials.

Nonadequate arrhythmia detection and delivery of electrical therapy is still a main problem in current implantable cardioverter defibrillator therapy. Besides supraventricular arrhythmias extra-cardiac biosignals also can cause inadequate shock delivery. The present study focuses on nonadequate arrhythmia detection due to oversensing of diaphragmatic myopotentials. Their clinical characteristics, incidence and management are presented. Three-hundred-eighty-four recipients of a transvenous cardioverter-defibrillator who were implanted and followed-up at our institution between October 1991 and June 1999 were enrolled. During a mean follow-up of 32+/-25 months a total number of 139 nonadequate episodes of arrhythmia detection due to oversensing of diaphragmatic myopotentials were observed in 33 patients (8.6%). In 11 patients a total of 32 high energy shock deliveries occurred. Oversensing of diaphragmatic myopotentials was primarily observed in patients implanted with defibrillator leads providing "integrated bipolar" sensing. The vast majority of nonadequate arrhythmia detection were observed during intrinsic bradycardia heart rate and/or antibradycardia pacing. Electrical lead failure was ruled out in every patient. In 90% of the patients with a cardioverter-defibrillator providing programmable maximal sensitivity (n=16), the reduction of maximum sensitivity was effective in preventing further episodes of nonadequate arrhythmia detection. In 48% of the patients with devices without programmable maximal sensitivity (n=17), surgery revision was necessary to solve the problem.

Reduction of pacing output coupling capacitance for sensing the evoked response.

Sensing of the intracardiac evoked response (ER) after a pacing stimulus has been used in implantable pacemakers for automatic verification of capture. Reliable detection of ER is hampered by large residual afterpotentials associated with pacing stimuli. This led to the development of various technological solutions, like the use of triphasic pacing pulses and low polarizing electrode systems. This study investigated the effect of reducing the coupling capacitance (CC) in the pacemaker output circuitry on the magnitude of afterpotential, and the ability to automate detection of ventricular evoked response. A CC of 2.2 microF and four different blanking and recharge time settings were clinically tested to evaluate its impact on sensing of the ventricular ER and pacing threshold. Using an automatic step-down threshold algorithm, 54 consecutive patients, aged 70 +/- 10 years with acutely (n = 27) or chronically (n = 27) implanted ventricular pacing leads were enrolled for measurement testing. Routine measurements, using a standard pacing system analyzer (PSA), were (mean +/- SD) impedance 569 +/- 155 omega, R wave amplitude baseline to peak 9.8 +/- 3.7 mV and threshold 0.9 +/- 0.7 V at 0.4-ms pulse width. This new capture verification scheme, based on a CC of 2.2 microF and recharge/blanking timing setting of 10/12 ms, was successful in 52 patients which is equivalent to a success rate of 96%. In a subgroup of 26 patients implanted with bipolar ventricular leads (10 chronic, 16 acute), data were collected in unipolar (UP) and bipolar (BP) pace/sense configurations. Also, ER signals were recorded with two different band-pass filters: a wider band (WB) of 6-250 Hz and a conventional narrow band (NB) of 20-100 Hz. WB sensing from UP lead configuration yielded statistically significant larger signal to artifact ratios (SAR) than the other settings (P < 0.01). A dedicated unipolar ER sensing configuration using a small output capacitor and a wider band-pass filter enables adequate automatic capture verification, without any restrictions on pacing lead models or pacing/sensing configurations.

Dual-coil vs single-coil active pectoral implantable defibrillator lead systems: defibrillation energy requirements and probability of defibrillation success at multiples of the defibrillation energy requirements.

AIMS: The aim of the study was to compare the defibrillation energy requirements and the probability of successful defibrillation at multiples of the minimum defibrillation energy requirements in active pectoral implantable defibrillators with single- and dual-coil lead systems. METHODS AND RESULTS: Eighty-three consecutive patients undergoing implantation of an active pectoral cardioverter-defibrillator were randomized to receive a dual- or single-coil lead system. Defibrillators of two manufacturers with a fixed tilt biphasic defibrillation waveform were used. Defibrillation energy requirements were determined using a step-down defibrillation testing protocol. According to the randomization protocol, the patients were assigned to three additional consecutive defibrillation attempts during device implantation and during pre-discharge testing of either 1.0, 1.5 or 2.0 times the determined defibrillation energy requirement. Patients presenting defibrillation energy requirements > 15 J were excluded from analysis. Eighty of 83 patients (96%) completed the study protocol. Three patients were excluded due to elevated defibrillation energy requirements. The defibrillation energy requirements in the dual- and single-coil patient groups were 8.0 +/- 3.6 J and 8.4 +/- 3.7 J (ns), respectively. A comparable percentage of study patients showed defibrillation energy requirements <10 J (dual-coil: 88% vs single-coil: 83%). Defibrillation impedance was significantly different (dual-coil: 50 +/- 5.8 Ohm; single-coil: 39.8 +/- 4.2 Ohm). Regarding the probabilities of successful defibrillation, there were no significant differences between the two patient groups. The probabilities of defibrillation at the three multiples of the defibrillation energy requirement using a dual- and single-coil lead system were 82, 89.7 and 93.6 and 77.8, 94.1 and 95.8%, respectively (P=0.88, P=0.42, P=0.62, respectively). CONCLUSIONS: Dual- and single-coil active pectoral defibrillator systems show no difference in defibrillation energy requirements and no difference in the probability of successful defibrillation at multiples of the minimum defibrillation energy requirement. The use of more simplified defibrillator lead systems may contribute to a future lead design focusing on improvement in lead durability.

[Clinical characteristics of patients with AV-nodal reentrant tachycardia (AVNRT): modification by high frequency catheter ablation. Study of 748 patients after high frequency catheter ablation]. / Klinische Charakteristika von Patienten mit AV-Knoten-Reentrytachykardie (AVNRT): Beeinflussung durch die Hochfrequenzkatheterablation. Untersuchung an 748 Patienten nach Hochfrequenzkatheterablation.

AIM: The aim of the study was to analyze the medical history of patients with AV-nodal reentry tachycardia (AVNRT). PATIENTS AND METHODS: Between 1990 and 1999 radiofrequency catheter ablation was performed in 1,024 patients suffering from AVNRT. Data of the previous history were comprehended by questionnaire. RESULTS: 748 (73%) patients replied to the questionnaire. The interval between the first appearance of the symptoms and the catheter ablation was 4.1 +/- 1.5 years. The mean age of the patients was 55.4 years (female) and 58.7 years (male). Merely 6% of all patients had a structural heart disease. The mean duration of case history was 16.8 years. In comparison to the male patients, the assignment for female patients to catheter ablation was after a significant 7 years longer lasting anamnesis. The distribution of age showed that the first tachycardia appeared in 16% of the female patients older than 50 years of age and only in 17% younger than 20 years of age; the corresponding percentages for men were 31% and 18%. With reference to the duration of the longest tachycardia episodes and arrhythmia-related presyncopes and syncopes, women showed a more defined symptomatic. On 20% of the patients a radiofrequency catheter ablation ensued without previous antiarrhythmic treatment; 80% of the patients were treated with 2.8 different antiarrhythmic medications. Medical consultations regarding AVNRT were named as follows (mean/range): family doctor 6.1/1-250, emergency physicians 1.1/0-15, hospital 1.0/0-20. The indication for catheter ablation was set by the family doctor in 13% and by the cardiologist in 77%. Patients got their information about catheter ablation in 2.9% from acquainted persons or news services. CONCLUSION: There is no "typical" anamnesis of AVNRT patients. There is an amazingly high rate of patients with an AVNRT begin in elder stage of age and the fact of therapy delay of 7 years in behalf of women.

Left ventricular leads used in cardiac resynchronization therapy for heart failure patients.

Cardiac resynchronization therapy (CRT) has been introduced as a treatment for selected heart failure patients, specifically those with symptomatic heart failure, left ventricular (LV) dysfunction, and intraventricular conduction delays. CRT is delivered by use of an implanted device and leads positioned in the right atrium, right ventricle, and left ventricle. In the early stages of CRT development, researchers affixed epicardial electrodes to the left ventricle by means of subxiphoid, thoracoscopic, or major surgical procedure. Currently there are a number of transvenous LV leads available that have undergone substantial evaluation. Reports indicate that such leads can be positioned safely by cannulating the coronary sinus and inserting the lead into the venous system. The leads are reported to have acceptable pacing/sensing thresholds and complication rates. Because of individual variations in the cardiac and venous anatomy, as well as sharp angulations in the venous system, maneuverability is an important consideration in lead selection.