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Background: A VDD-implantable cardioverter-defibrillator (ICD) provides atrioventricular (AV) synchronous stimulation when necessary and incorporates the advantages of dual chamber arrhythmia discrimination algorithms both at potentially lower costs and less periprocedural complications than a DDD-ICD system. A prerequisite for correct dual chamber ICD function is reliable atrial sensing. Methods: We evaluated atrial near- and ventricular far-field sensing and its impact on the dual-chamber detection algorithm in 106 patients with a single-lead VDD-ICD during a 12-month follow-up period. Results: Six hundred and thirty-nine follow-ups were included. Mean near-field amplitude was 3.82 ± 1.76 mV; mean far-field amplitude was 0.31 ± 0.15 mV. 46% of patients had far-fields >0.35 mV and 35% of patients showed atrial EGM markers corresponding to a ventricular far-field in at least one follow-up. Six hundred and forty-five tachycardia episodes were evaluated. Due to far-field sensing, three of 66 episodes (4.5%) of sinus tachycardia were misclassified as ventricular tachycardia (VT), leading to antitachycardia therapies. Delayed detection of VT was seen in a 12 of 323 episodes (3.7%) in five of 62 patients (8%) having VT events (delay 6.4 ± 6.0 seconds (range 2–24 seconds)). Stable far-field amplitudes <0.2 mV in a follow-up had a high negative predictive value for the occurrence of malfunction during tachycardia—conversely, high far-field amplitudes or a high incidence of far-field markers are only moderately correlated with malfunction. Conclusions: Ventricular far-field sensing in a VDD-ICD is not uncommon, however, tachycardia detection by the dual chamber algorithm is not seriously impaired by far-field sensing. [ABSTRACT FROM AUTHOR]

Background: Psychological distress is common in patients with cardiovascular disease and negatively impacts outcome. Hypothesis: Psychological distress is high in acute high risk cardiac patients eligible for a WCD, and associated with low quality of life. Distress is aggravated by WCD. Methods: Consecutive patients eligible for a WCD were included in the prospective, multicenter “Cologne Registry of External Defibrillator” registry. Quality of life (Short Form-12), depressive symptoms (Beck-Depression Inventory II) and anxiety (State Trait Anxiety Inventory) were assessed at enrollment and 6-weeks, and associations with WCD prescription were analyzed. Results: 123 patients (mean [SD] age 59 [± 14] years, 75% male) were included, 85 (69%) of whom received a WCD. At enrollment 21% showed clinically significant depressive symptoms and 52% anxiety symptoms, respectively. At 6 weeks, depressive and anxious symptoms significantly decreased to 7% and 25%, respectively. Depressive symptoms at enrollment and changes at 6 weeks showed significant associations with health-related quality of life, whereas anxious symptoms did not. There was a trend for better improvement of depression scores in patients with WCD (mean [SD] change in score points: -4.1 [6.1] vs -1.8 [3.9]; p = 0.09), whereas change of the anxiousness score was not different (-4.6 [9.5]) vs -3.7 [9.1], p = 0.68). Conclusion: In patients eligible for a WCD, depressive and anxiety symptoms were initially common and depressive symptoms showed a strong association with reduced health-related quality of life contributing to their clinical relevance. WCD recipients showed at least similar improvement of depression and anxiety at 6 weeks when compared to non recipients. [ABSTRACT FROM AUTHOR]

This article reports on a case of ventricular undersensing despite normal R wave amplitudes during sinus rhythm in an ICD patient. Undersensing of ventricular signals was noted without any evidence of lead dislocation or variation in signal amplitude. Undersensing was due to an exceptionally small R wave signal width and a feature of the Biotronik sensing algorithm designed to avoid oversensing. This algorithm, intended to enhance the sensing specifity of the device, requires registration of two consecutive points above the maximum programmed sensitivity for a ventricular sense event. After modifying the algorithm to a single point registration undersensing disappeared. (PACE 2003; 26:1776–1777). [ABSTRACT FROM AUTHOR]

Background and Methods: Biventricular pacing improves hemodynamics after weaning from cardiopulmonary bypass in patients with severely reduced left ventricular (LV) function undergoing coronary artery bypass grafting (CABG). We examined the feasibility of temporary biventricular pacing for 96 hours postoperatively. Unipolar epicardial wires were placed on the roof of the right atrium (RA), the right ventricular (RV) outflow tract, and the LV free lateral wall and connected to an external pacing device in 51 patients (mean LV ejection fraction 35 ± 4%). Pacing and sensing thresholds, lead survival and incidence of pacemaker dysfunction were determined. Results: Atrial and RV pacing thresholds increased significantly by the 4th postoperative day, from 1.6 ± 0.2 to 2.5 ± 0.3 V at 0.5 ms (P = 0.03) at the RA, 1.4 ± 0.3 V to 2.7 ± 0.4 mV (P = 0.01) at the RV, and 1.9 ± 0.6 V to 2.9 ± 0.7 mV (P = 0.3) at the LV, while sensing thresholds decreased from 2.0 ± 0.2 to 1.7 ± 0.2 mV (P = 0.18) at the RA, 7.2 ± 0.8 to 5.1 ± 0.7 mV (P = 0.05) at the RV, and 9.4 ± 1.3 to 5.5 ± 1.1 mV (P = 0.02) at the LV. The cumulative overall incidence of lead failure was 24% by the 4th postoperative day, and was similar at the RV and LV. We observed no ventricular proarrhythmia due to pacing or temporary pacemaker malfunction. Conclusions: Biventricular pacing after CABG using a standard external pacing system was feasible and safe. [ABSTRACT FROM AUTHOR]

Background: In atrial-based pacing, appropriate therapy and reliable diagnostics depend on detection and discrimination of atrial signals. Accurate classification of atrial events is mainly confounded by oversensing of ventricular far-field R-wave signals (FFRW), but attempts to reject FFRWs by manipulating atrial sensitivity and/or postventricular atrial blanking period (PVAB) may result in undersensing (especially of atrial fibrillation, AF) or in 2:1 atrial flutter detection. The objective of this study is therefore to evaluate if such methods can be improved by morphology-enhanced atrial event classification (MORPH). Methods: Twenty-four-hour ambulatory atrial electrograms were recorded from continuous telemetry of digital pacemakers. Half of the recording was used for collecting two individual morphology parameters that discriminated P-waves from FFRWs in every patient (learning phase). The other half was used to test the MORPH algorithm against traditional methods (classification phase). Results: In 44/48 patients, data were suitable for analysis. Average P and FFRW amplitudes were 1.96 mV versus 0.61 mV (P < 0.001). The interval between ventricular events and FFRW oversensing (VA interval) averaged at 14 ms during sensing and at 118 ms during pacing in the ventricle. Compared to nominal (“Factory”) settings, the MORPH algorithm improved the sensitivity for P-wave recognition from 97.2% to 99.2%, the specificity from 91.9% to 99.96%, and the accuracy from 95.3% to 99.4% (P < 0.01 for all). Conclusions: By improving atrial signal discrimination, morphology analysis of atrial electrograms allows for high atrial sensitivity settings, and potentially improves the reliability of atrial arrhythmia diagnostics in heart rhythm devices. [ABSTRACT FROM AUTHOR]

Objective: The modified algorithm for the non-invasive determination of cardiac output (CO) by electrical bioimpedance-electrical velocimetry (EV)-has been reported to give reliable results in comparison with echocardiography and pulmonary arterial thermodilution (PA-TD) in patients either before or after cardiac surgery. The present study was designed to determine whether EV-CO measurements reflect intraindividual changes in CO during cardiac surgery.Design: Prospective, observational study.Setting: Operating room (OR) and intensive care unit (ICU) of a university hospital.Patients: Twenty-nine patients undergoing elective cardiac surgery.Interventions: None.Measurements: CO was determined simultaneously by PA-TD and EV after induction of anesthesia (t1) and 4.9+/-3.5 h after ICU admission (t2).Results: TD-CO was 3.9+/-1.4 and 5.4+/-1.1 l/min at t1 and t2 (p < 0.0001). EV-CO was 4.3+/-1.1 and 4.9+/-1.5 l/min at t1 and t2 (p = 0.013). Bland-Altman analysis showed a bias of -0.4 l/min and 0.4 l/min and a precision of 3.2 and 3.6 l/min (34.3% and 67.4%) at t1 and t2, respectively. Analysis of the individual pre- to postoperative changes in CO with both methods revealed bidirectional changes in n = 12 patients and unidirectional changes with a difference greater than 50% and less than 50% in n = 9 and n = 8 patients, respectively.Conclusions: The disagreement between PA-TD and EV-CO measurements after anesthesia induction and after ICU admission, as well as the fact that thoracic bioimpedance did not adequately reflect pre- to postoperative changes in CO, questions the reliability of EV-CO measurements in cardiac surgery patients and contrasts sharply with previous studies. [ABSTRACT FROM AUTHOR]

ORTAK, J.,et al.: Changes in Heart Rate, Heart Rate Variability, and Heart Rate Turbulence during Evolving Reperfused Myocardial Infarction. Depressed cardiac parasympathetic activity is associated with electrical instability and adverse outcomes after myocardial infarction (MI). Heart rate turbulence (HRT), reflecting reflex vagal activity, and heart rate variability (HRV), reflecting tonic autonomic variations are both reduced in the subacute phase of MI. However, the evolution of these components of cardiac autonomic control between subacute and chronic phase of MI has not been defined. We prospectively studied 100 consecutive patients with a recent first MI with ST-segment elevation, who underwent successful direct percutaneous coronary interventions. Beta-adrenergic blockers and angiotensin-converting enzyme (ACE) inhibitors were administered according to the state-of-the-art medical practice guidelines. HRT and HRV were measured from 24-hour ambulatory electrocardiographic recordings 10 days and 12 months after the index MI. There was no significant difference in mean RR interval between the subacute and chronic phase of MI (875± 145 versus 859± 122 ms). Indices of HRV increased significantly during the observation period (SDNN: from 88.8± 26.8 to 116.0± 35.7 ms, P<0.001; SDNNi: from 37.9± 15.9 to 46.0± 16.3 ms, P<0.001; SDANN: from 79.6± 34.7 to 105.6± 35.4 ms, P<0.001). In contrast, there were no significant changes in indices of HRT (turbulence onset: from−0.008± 0.022 to−0.012± 0.025%; turbulence slope: from 7.78± 5.9 to 8.06± 6.8 ms/beat). In contrast to reflex autonomic activity, there was a significant recovery of tonic autonomic activity within 12 months after MI. These different patterns of recovery of reflex versus tonic cardiac autonomic control after MI need to be considered when risk stratifying post-MI patients.(PACE 2005; 28:S227–S232) [ABSTRACT FROM AUTHOR]

Study objectives: Pocket hematoma is a common complication after pacemaker or implantable cardioverter defibrillator (lCD) implantation. Thus, we investigated the influence of patient comorbidity, implantation strategy, operator experience, antiplatelet therapy, and anticoagulation therapy on hematoma rate. Design: Between 1990 and 2002, a total of 3,164 devices (pectoral pacemakers, 2,792; ICDs, 372) were implanted at our institution. Predictors of hematoma occurrence were determined prospectively and were analyzed by multivariate regression analysis. Operator experience was graded by individual implantation number, as follows: low, <50; medium, 50 to 100; and high, > 100. Results: The incidence of pocket hematoma was 4.9%, leading to prolonged hospitalization in 2.0% of all patients. Reoperation for pocket hematoma was required in 1.0% of patients. High-dose heparinization (hazard ratio [HR], 4.2), combined acetylsalicylic acid (ASA)/thienopyridine treatment after coronary stenting (HR, 5.2), and low operator experience (HR, 1.6) were independently predictive of hematoma development. Therapy with ASA alone did not increase the hematoma rate compared to patients who did receive antiplatelet or anticoagulation therapy (3.1% vs 2.5%, respectively; difference not significant). In patients with nonvalvular atrial fibrillation, postoperative high-dose heparinization substantially increased the hematoma rate (10.7% vs 2.9%, respectively; p < 0.001) without reducing the rate of arterial embolism within the first month after implantation (0.18% vs 0.2 1%, respectively; difference not significant). The infection rate (0.2 8% within 3 months after implantation) was not influenced by the presence of the pocket hematoma. Conclusions: The use of high-dose heparinization and combined ASA/thienopyridine treatment are highly predictive for the occurrence of intraoperative bleeding and pocket hematoma in patients who have undergone pacemaker and lCD surgery. We propose recommendations for the management of antiplatelet and anticoagulation therapy in patients undergoing these interventions. [ABSTRACT FROM AUTHOR]

Right ventricular lead perforation, when acute, is a rare but potentially life-threatening complication of implantable cardioverter defibrillator (ICD) therapy. We report about a patient with early lead perforation presenting with repetitive ICD discharges due to oversensing of diaphragmatic electromyopotentials and describe the management of this complication. [ABSTRACT FROM AUTHOR]

A letter to the editor is presented in response to the article on the comparison of cardiac output (CO) measurements by pulmonary artery catheter thermodilution (TDCO) and electrical velocimetry (EVCO) that was published in the previous issue.

Background: Imbalance of cardiac autonomic nervous modulation might prominently contribute to early relapses of atrial fibrillation (AF) after cardioversion (CV). The biphasic (Bi) waveform is more effective than the monophasic (Mo) waveform in CV of AF. Whether these waveforms have different effects on autonomic modulation early after CV is unknown. Methods: We investigated 171 consecutive patients after successful electrical CV (mean age 65.4 years, 82% male, 80% structural heart disease). Bi waveform was used in 89, Mo waveform in 82. Heart rate variability (HRV) was analyzed from 24-hour Holter recordings, started directly after CV. Results: Mean delivered total energy was significantly lower in the Bi group (Bi 223 ± 163 W, Mo 355 ± 211 W, P < 0.001). Mean RR interval decreased within 5 hours after CV and increased again within the remaining hours, without significant differences between Bi and Mo groups. Time courses of time domain parameters of HRV revealed Bi profiles with the lowest levels 6 hours after CV in both groups. However, the hourly values of HRV were significantly higher in the Bi subgroup. Conclusion: Our study indicates that waveform and total delivered energy significantly influence autonomic modulation of the sinus node in the early phase after CV of AF. In contrast to Bi CV, Mo CV is characterized by a significant decrease of cardiac vagal modulation, which may have an arrhythmic effect by increasing the degree of early electrical stunning after CV of AF. [ABSTRACT FROM AUTHOR]