Should all dysfunctional high-voltage leads be extracted? Results of a single-centre long-term registry.

AIMS: A considerable number of lead defects occurs during long-term cardioverter defibrillator therapy. Evidence-based strategies for the handling of chronically implanted, non-functional high-voltage (HV) leads are mandatory. METHODS AND RESULTS: Patient outcome after abandonment of HV leads was retrospectively compared with patient outcome following other lead revision strategies and following primary implantation. A total of 903 consecutive patients undergoing 997 implantable cardioverter defibrillator (ICD) implantations or lead revisions were followed for a mean period of 48.8 ± 37.8 months. One or more additional HV leads were placed in 60 patients. An additional pace/sense lead was implanted in 13 patients. Extraction and replacement of a dysfunctional HV lead was performed in 21 patients. The overall rate of complications including artefact sensing, ineffective defibrillation, symptomatic subclavian vein thrombosis, and other lead defects did not differ between patients with and without an additional HV lead (10.0 vs. 8.9%, P = 0.32). Survival without lead associated complications did not differ between groups. Results remained unchanged after correction for covariates. CONCLUSIONS: Abandoned HV leads did not increase the risk of ICD system-related complications in the majority of patients. Thus, a general lead extraction policy of dysfunctional HV leads cannot be advised in an average ICD population. Recommendations may not apply for young and physically active patients, in whom HV lead extraction must be considered.

AV interval optimization using pressure volume loops in dual chamber pacemaker patients with maintained systolic left ventricular function.

BACKGROUND: Atrioventricular (AV) interval optimization is often deemed too time-consuming in dual-chamber pacemaker patients with maintained LV function. Thus the majority of patients are left at their default AV interval. OBJECTIVE: To quantify the magnitude of hemodynamic improvement following AV interval optimization in chronically paced dual chamber pacemaker patients. PATIENTS AND METHODS: A pressure volume catheter was placed in the left ventricle of 19 patients with chronic dual chamber pacing and an ejection fraction >45 % undergoing elective coronary angiography. AV interval was varied in 10 ms steps from 80 to 300 ms, and pressure volume loops were recorded during breath hold. RESULTS: The average optimal AV interval was 152 ± 39 ms compared to 155 ± 8 ms for the average default AV interval (range 100-240 ms). The average improvement in stroke work following AV interval optimization was 935 ± 760 mmHg/ml (range 0-2,908; p < 0.001), which translates into an average improvement of 14 ± 9 % (range 0-28). A 10 ms variation of the AV interval changes the average stroke work by 207 ± 162 mmHg/ml. AV interval optimization also leads to improved systolic dyssynchrony indices (17.7 ± 7.0 vs. 19.4 ± 7.1 %; p = 0.01). CONCLUSION: The overall hemodynamic effect of AV interval optimization in patients with maintained LV function is in the same range as for patients undergoing cardiac resynchronization therapy for several parameters. The positive effect of AV interval optimization also applies to patients who have been chronically paced for years.

The effect of biventricular pacing on cardiac function after weaning from cardiopulmonary bypass in patients with reduced left ventricular function: a pressure-volume loop analysis.

OBJECTIVE: Patients with severely reduced left ventricular function undergoing coronary artery bypass grafting have increased complication rates. We hypothesized that temporary postoperative atrial synchronous biventricular pacing would improve left ventricular function after cardiopulmonary bypass. METHODS: A left ventricular pressure-volume catheter was placed in 21 patients undergoing coronary artery bypass grafting (ejection fraction 29% +/- 5%). Pressure-volume loops were obtained after weaning from cardiopulmonary bypass with atrial synchronous biventricular, left ventricular, and right ventricular outflow tract pacing and atrial-only stimulation at 90 beats/min. RESULTS: Steady-state systolic and preload-independent parameters were superior for atrial synchronous biventricular and left ventricular pacing and atrial-only pacing relative to atrial synchronous right ventricular outflow tract pacing (P < .05). Diastolic parameters, excepting maximum negative rate of left ventricular pressure change, were unaffected. No significant differences were observed between atrial synchronous biventricular and left ventricular pacing and atrial-only pacing. Systolic dyssynchrony was significantly lower for atrial synchronous biventricular pacing (21% +/- 5%), atrial synchronous left ventricular pacing (20% +/- 6%), and atrial-only pacing (20% +/- 6%) versus atrial synchronous right ventricular outflow tract pacing (25% +/- 7%, P < .05). Atrioventricular interval during atrial-only stimulation was positively correlated with difference in stroke work between atrial synchronous biventricular pacing and atrial-only pacing (r(2) = 0.78, P > .001). CONCLUSION: Postoperative atrial synchronous biventricular and left ventricular pacing and atrial-only stimulation significantly improve systolic function relative to atrial synchronous right ventricular outflow tract pacing. If atrioventricular conduction is prolonged, atrial synchronous biventricular pacing is preferable to atrial-only pacing.

The effect of biventricular pacing after coronary artery bypass grafting: a prospective randomized trial of different pacing modes in patients with reduced left ventricular function.

OBJECTIVES: Biventricular pacing acutely improves left ventricular function in patients with heart failure and left ventricular dyssynchrony. Pressure-volume loop analysis has shown acute perioperative hemodynamic benefits of biventricular pacing immediately after weaning from cardiopulmonary bypass in patients undergoing coronary artery bypass grafting, but whether these effects can be maintained for the early postoperative period is unclear. We hypothesized that biventricular pacing is superior to atrioventricular universal pacing at right ventricular outflowtract and atrial inhibited pacing in patients undergoing coronary artery bypass grafting. METHODS: Ninety-four patients (mean age, 67 +/- 9 years; mean ejection fraction, 35% +/- 4%) were prospectively randomized to undergo biventricular, atrioventricular universal, or atrial inhibited pacing at 90 beats/min for 96 postoperative hours. Clinical end points and postoperative hemodynamics, aminoterminal pro-brain natriuretic peptide, inotropic support, atrial fibrillation, ventricular arrhythmias, and renal function were evaluated. RESULTS: Diastolic pulmonary arterial pressure, mean arterial pressure, mixed venous saturation, cardiac index, and cardiac power index did not differ significantly among groups for all time points. Neither raw aminoterminal pro-brain natriuretic peptide nor differential from preoperative values differed significantly among groups at any time point. Median intensive care unit stay (19.5 hours) did not differ significantly by pacing mode. Incidences of postoperative atrial fibrillation were 40% for atrial inhibited, 29% for atrioventricular universal, and 37% for biventricular (differences not significant). Renal function was unaffected by pacing mode. CONCLUSION: Despite short-term hemodynamic benefits for patients with reduced left ventricular function, biventricular pacing did not lead to improved postoperative hemodynamics or clinical outcome.

Evolution of cardiac autonomic nervous activity indices in patients presenting with transient left ventricular apical ballooning.

BACKGROUND: Transient left ventricular (LV) apical ballooning (AB) is characterized by a rapidly reversible, acute LV systolic dysfunction, triggered by physical or emotional stress. Despite observations strongly suggesting catecholamine-mediated myocardial stunning due to enhanced sympathetic activity, the early time course of heart rate variability (HRV) has not been described. METHODS: We prospectively enrolled 39 consecutive patients (median age = 68 years, range 35-85 years, 38 women) with LV AB. Indices of HRV were extracted from 24-hour ambulatory electrocardiograms on the day of hospital admission, on days 2 and 3, and 3 months after the hospitalization. RESULTS: Within 48 hours after hospital admission, the indices of HRV were markedly depressed (standard deviation of normal-to-normal [NN] intervals [SDNN] 89.6 +/- 19.9 ms; mean standard deviation of NN intervals for 5-minute segments [SDNNi] 37.8 +/- 6.2 ms; root mean square of consecutive difference of normal-to-normal intervals [rMSSD] 23.0 +/- 9 ms; standard deviation of the averages of NN intervals for all 5-minute segments [SDANN] 70.1 +/- 18.0 ms; geometric triangular index [TI] 23.7 +/- 5.9 ms), recovered in the subacute phase and had normalized at 3 months follow-up (SDNN 124.7 +/- 24 ms; SDNNi 47.1 +/- 5.7 ms; rMSSD 31.1 +/- 10.5 ms; SDANN 118.5 +/- 27 ms; TI 31.2 +/- 8 ms; all P < 0.05). Mean RR-interval increased from 845 +/- 121 ms on day 1, to 929 +/- 84 ms at 3 months (P=0.06). CONCLUSIONS: A marked depression of cardiac parasympathetic activity was observed in the acute phase of LV AB, followed by recovery of autonomic modulation between the subacute and the chronic phases. The rapid return of parasympathetic function may partially explain the favorable outcomes of patients presenting with LV AB.

The effects of facilitated primary PCI by guide wire on procedural and clinical outcomes in acute ST-segment elevation myocardial infarction.

BACKGROUND: Reperfusion of the infarct related artery (IRA) prior to PCI is prognostically important in patients with acute ST segment elevation myocardial infarction (STEMI). Reperfusion is either achieved spontaneously, facilitated by GP IIb/ IIIa inhibitors, or mechanically by crossing the guide wire beyond the lesion. In order to test the hypothesis that a visible coronary anatomy is independently associated with procedural and clinical outcomes, we evaluated the frequency and prognostic impact of guide wire facilitated reperfusion of the IRA before primary PCI. METHODS AND RESULTS: We enrolled 311 consecutive patients with successful primary PCI for STEMI (TIMI grade > or =2 flow) within 12 h after onset of symptoms. Among these, 90 patients (28.9%) had a spontaneously reperfused IRA on initial angiogram, 56 patients (18.0%) achieved reperfusion after crossing of the guide wire, and 165 patients (53.1%) successful reperfusion only after PCI. Variables associated with successful guide wire facilitated reperfusion were younger age, no history of arterial hypertension, active smoking status, negative cardiac troponin T on admission, and an infarct in the territory of the right coronary artery. Patients with spontaneous reperfusion or reperfusion after crossing of the guide wire required less fluoroscopic time and less contrast material during angiography and had higher procedural success rates (TIMI grade 3 flow 91.1 vs 79.4%, p=0.048) than patients without initial reperfusion. In addition, patients with reperfusion after crossing the lesion with the guide wire had lower mortality rates at 30 days (3.6 vs 9.1%) and after a median of 16 months (3.6 vs 13.9%, p=0.03) than those with reperfusion after PCI. CONCLUSIONS: Reperfusion of an occluded IRA by crossing the guide wire is associated with higher procedural success rates and better outcomes. Better roadmapping and device selection represent potential reasons but the exact mechanism for these benefits is still illusive.

Modulation of cardiac autonomic nervous activity early after cardioversion of atrial fibrillation by biphasic waveform.

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.

Feasibility of temporary biventricular pacing in patients with reduced left ventricular function after coronary artery bypass grafting.

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.

Modulation of ventricular repolarization in patients with transient left ventricular apical ballooning: a case control study.

OBJECTIVE: Even though diffuse T wave inversion and prolongation of the QT interval in the surface electrocardiogram (ECG) have been consistently reported in patients with transient stress-induced left ventricular apical ballooning (AB), ventricular repolarization has not yet been systematically investigated in this clinical entity. BACKGROUND: AB, an emerging syndrome that mimics acute ST-segment elevation myocardial infarction (MI), is characterized by reversible left ventricular wall motion abnormalities in the absence of obstructive coronary heart disease and significant QT interval prolongation. METHODS: We prospectively enrolled 22 consecutive patients (21 women, median age 65 years) with transient left ventricular AB. A total of 22 age-, gender-, body-mass-index-, and left-ventricular-function-matched patients with acute anterior ST-segment elevation MI undergoing successful direct percutaneous coronary intervention for a proximal occlusion of the LAD, as well as 22 healthy volunteers served as control groups. Beat-to-beat QT interval and QT interval dynamicity were determined from 24-hour Holter ECGs, recorded on the third day after hospital admission. RESULTS: There were no significant differences in baseline clinical characteristics, except higher peak enzyme release in MI patients. Compared with MI patients, AB patients exhibited significantly prolonged mean QT intervals and rate-corrected QT intervals (QT: 418 +/- 37 vs 384 +/- 33 msec, P < 0.01; QTcBazett: 446 +/- 40 vs 424 +/- 35 msec, P < 0.05; QTcFridericia: 437 +/- 35 vs 412 +/- 31 msec, P < 0.05). Mean RR intervals tended to be higher in AB patients, without reaching statistical significance (877 +/- 96 vs 831 +/- 102 msec, P = NS). The linear regression slope of QT intervals plotted against RR intervals was significantly flatter in AB patients at both day- and nighttime (QT/RR slopeday: 0.18 +/- 0.04 vs 0.22 +/- 0.06, P < 0.01; QT/RR slopenight: 0.12 +/- 0.03 vs 0.17 +/- 0.05, P < 0.01). CONCLUSION: The present study is the first to demonstrate significant differences of QT interval modulation in patients with transient left ventricular AB and acute ST-segment elevation MI. Even though transient AB is associated with a significant QT interval prolongation, rate adaptation of ventricular repolarization (i.e., QT dynamicity) is not significantly altered, suggesting a differential effect of autonomic nervous activity on the ventricular myocardium in transient AB and in acute MI.

Inadequate ICD discharges due to diaphragmatic electromyopotential oversensing as the first sign of right ventricular lead perforation.

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.

Ventricular fibrillation induced by stretch pulse: implications for sudden death due to commotio cordis.

INTRODUCTION: Nonpenetrating chest wall impact (commotio cordis) may lead to sudden cardiac death due to the acute initiation of ventricular fibrillation (VF). VF may result from sudden stretch during a vulnerable window, which is determined by repolarization inhomogeneity. METHODS: We examined action potential morphologies and VF inducibility in response to sudden myocardial stretch in the left ventricle (LV). In six Langendorff perfused rabbit hearts, the LV was instrumented with a fluid-filled balloon. Increasing volume and pressure pulses were applied at different times of the cardiac cycle. Monophasic action potentials (MAPs) were recorded simultaneously from five LV epicardial sites. Inter-site dispersion of repolarization was calculated in the time and voltage domains. RESULTS: Sudden balloon inflation induced VF when pressure pulses of 208-289 mmHg were applied within a window of 35-88 msec after MAP upstroke, a period of intrinsic increase in repolarization dispersion. During the pressure pulse, MAPs revealed an additional increase in repolarization dispersion (time domain) by 9 +/- 6 msec (P < 0.01). The maximal difference in repolarization levels (voltage domain) between sites increased from 19 +/- 3% to 26 +/- 3% (P < 0.05). Earliest stretch-induced activation was observed near a site with early repolarization, while sites with late repolarization showed delayed activation. CONCLUSIONS: Sudden myocardial stretch can elicit VF when it occurs during a vulnerable window that is based on repolarization inhomogeneity. Stretch pulses applied during this vulnerable window can lead to nonuniform activation. Repolarization dispersion might play a crucial role in the occurrence of fatal tachyarrhythmias during commotio cordis.

Atrial near-field and ventricular far-field analysis by automated signal processing at rest and during exercise.

INTRODUCTION: Sophisticated monitoring of atrial activity is a prerequisite for modern pacemaker therapy. Ideally, near-fields and ventricular far-fields ought to be distinguished by beat-to-beat template analysis of the atrial signal. A prerequisite is that atrial signals are stable under different conditions. METHODS AND RESULTS: A Matlab routine was developed to analyze atrial electrograms of 23 patients at least 3 months after implantation of a dual chamber pacemaker under several conditions including at rest, bipolar at rest, in an upright position, during treadmill exercise, and postexercise. A near-field and far-field template was created and amplitudes, widths, and slew rates were measured. In bipolar configuration, near-field amplitude at rest was 3.04 +/- 0.94 mV (unipolar)/3.36 +/- 1.0 mV (bipolar) versus 3.18 +/- 1.0 mV (bipolar) at peak exercise. Far-field amplitude at rest was 1.66 +/- 1.18 (unipolar)/0.47 +/- 0.27 mV (bipolar) and 0.41 +/- 0.21 mV (bipolar) at peak exercise (n.s. for bipolar measurements). No overall significant changes were observed for near- and far-field widths and slew rates during exercise. Shorter tip-ring distances of the atrial bipole, lead position, and the presence of sinus node disease did not have any impact on overall near- and far-field signal characteristics. Intraindividual differences between rest and peak exercise were moderate (range: near-field +0.15 to -0.54 mV; range: far-field +0.05 to -0.18 mV). CONCLUSIONS: Atrial near and far fields can be automatically classified and quantified by automated signal processing. Signals did not change during exercise or change of posture. This is a prerequisite for the implementation of beat-to-beat template analysis into pacemakers.

Effect of adjunctive treatment with tirofiban on troponin T elevation during stenting of critically stenosed aortocoronary saphenous vein grafts.

In this pilot study, we show that periprocedural administration of tirofiban during stenting of critically stenosed saphenous vein grafts, significantly reduces the occurrence of postprocedural minor myocardial necroses.

Very early cardiac magnetic resonance imaging for quantification of myocardial tissue perfusion in patients receiving tirofiban before percutaneous coronary intervention for ST-elevation myocardial infarction.

BACKGROUND: Assessment of myocardial blood flow is important for identification and monitoring of microvascular effects of glycoprotein IIb/IIIa inhibitors. Magnetic resonance imaging is a novel noninvasive method providing complementary information on myocardial blood flow and cardiac function. METHODS AND RESULTS: Patients (n = 53) admitted within 12 (mean, 5.8) hours after onset of symptoms were randomized to tirofiban or standard therapy before primary percutaneous coronary intervention (PCI) with stenting. Myocardial blood flow was graded by measurement of corrected Thrombolysis in Myocardial Infarction frame counts and by semiquantitative analysis of signal intensity curves from first-pass contrast-enhanced magnetic resonance perfusion. Pretreatment with tirofiban proved safe and resulted in a significantly lower corrected Thrombolysis in Myocardial Infarction frame counts (21 vs 34, P = .008) indicating improved myocardial blood flow. Magnetic resonance imaging revealed higher normalized peak signal intensities (2.19 vs 1.63, P = .046) and a trend to steeper upslopes (0.79 vs 0.48, P = .1). Cardiac left ventricular wall motion analysis resulted in a significantly lower number of myocardial segments with abnormal wall thickening (6.4 vs 8.5, P = .025). CONCLUSIONS: Pretreatment with tirofiban appears safe and improves myocardial flow after primary PCI with stenting. Magnetic resonance imaging proved useful as a complementary method for noninvasive assessment of myocardial blood flow and cardiac function in patients with ST-segment elevation myocardial infarction undergoing primary PCI.