Osman Balta

Postablation asymptomatic cerebral lesions: Long-term follow-up using magnetic resonance imaging

BACKGROUND Catheter ablation of atrial fibrillation (AF) is complicated by cerebral emboli resulting in acute ischemia. Recently, cerebral ischemic microlesions have been identified with diffusion-weighted magnet resonance imaging (MRI). OBJECTIVE The clinical course and longer-term characteristics of these lesions are not known and were investigated in this study. METHODS Of 86 patients, 33 (38%) had new asymptomatic cerebral lesions documented on MRI after catheter ablation for AF; 14 of these 33 (42%) underwent repeat MRI at different time intervals (2 weeks to 1 year) during follow-up, and clinical symptoms as well as size and number of residual lesions were documented. RESULTS In postablation cerebral MRI, 50 new lesions were identified (3.6 lesions/patient) in 14 patients. No patient presented any neurological symptoms. Distribution of the lesions was predominantly in the left hemisphere (60%) and the cerebellum (26%); 52% of the lesions were small (≤3 mm maximum diameter), 42% were medium (4 to 10 mm) and 3 lesions (6%) had a maximum diameter >10 mm. Follow-up MRI after a median of 3 months revealed 3 residual lesions in 3 of 14 patients corresponding to the large acute postablation lesions (>10 mm). The remaining 47 of 50 (94%) of the small or medium-sized lesions were not detectable at follow-up evaluation. CONCLUSIONS Most asymptomatic cerebral lesions observed acutely after AF ablation procedures were ≤10 mm in diameter. 94% of all lesions healed without scarring at follow-up >2 weeks after ablation. The larger acute lesions produced chronic glial scars. Neither chronic nor acute lesions were associated with neurological symptoms.

Catheter Ablation of Electrical Storm in a Collaborative Hospital Network

An electrical storm (ES) is defined as multiple ventricular arrhythmia episodes leading to implantable cardioverter defibrillator interventions. Although conventional rhythm stabilization might be of help acutely, ES involves high mortality and morbidity. We evaluated the effect of catheter ablation strategies in the setting of an interhospital collaborative network on the recurrence of ventricular arrhythmia episodes and mortality in patients with ES. Consecutive patients presenting for invasive treatment of ES from December 2007 to December 2009 were included. All patients underwent catheter ablation of ventricular arrhythmia. The strategies were adapted to the individual cardiac pathologic features. The follow-up examination constituted periodic implantable cardioverter defibrillator interrogation. A total of 32 patients were included. Of the 32 patients, 29 (91%) had monomorphic ventricular tachycardia and 3 ventricular fibrillation. The mean number of implantable cardioverter defibrillator-treated episodes within 7 days before ablation was 16 ± 11. Of the 32 patients, 27 underwent ablation within 24 hours after admission, and 5 underwent acute ablation within 8 hours. In 3 patients, epicardial ablation was performed. In all but 2 patients (6%), the clinical arrhythmia was successfully ablated. During a median follow-up of 15 months, 10 patients (31%) had recurrences of sustained ventricular arrhythmia, including 2 patients (6%) with recurrent ES. Three patients (9%) died during the follow-up period. In conclusion, catheter ablation effectively suppressed ventricular arrhythmia midterm recurrences in patients presenting with ES. Catheter ablation is complex in these severely sick patients. The recurrence rate of ventricular arrhythmia appears to be 31% and the mortality rate to be 9%. Collaborative hospital networks to increase the prompt availability of ES ablation might help to optimize the ES outcome.

Impact of age and basic heart rate on heart rate turbulence in healthy persons.

Postextrasystolic acceleration of heart rate (HR), known as HR turbulence (HRT) is attenuated in patients with coronary artery disease at increased risk of adverse events. The influence of age and basic HR on HRT have not been evaluated in a large cohort of persons. In 95 healthy individuals, HRT onset (TO) and slope (TS) were calculated from 24‐hour ambulatory electrocardiograms, as well as the turbulence timing (TT). Gender specific differences in TO and TS were compared in simple, linear, weighted regression model. The influence of age and the basic HR preceding ventricular premature contractions on HRT were examined. We found that, in men and women, TO decreases as basic HR increases (P < 0.01). In contrast, in men, TS decreased as basic HR increases, whereas in women, basic HR influenced TS only slightly (P < 0.01). A multiple, linear regression model revealed a decrease in HRT with increasing age in men. In conclusion, physiological acceleration of the HR within the first 11 beats after premature ventricular complex (VPC) was observed in >75% of healthy individuals. An accelerating HR preceding the VPC influenced HRT in men. An increasing age was associated with a decrease in HRT in men and a decrease in TO in women. These results illustrate the importance of physiological modulations of HRT when used for risk stratification, especially in older populations.

Catheter ablation of electrical storm.

Electrical storm (ES) is defined as the occurrence of ≥ three distinct episodes of ventricular arrhythmia (VA) in patients with implanted defibrillators within 24 h. Whereas conventional strategies for acute rhythm stabilization may be effective in some patients the occurrence of ES impairs survival and predicts recurrent VA. Catheter ablation in the setting of ES is complex and involves decisive strategies for individualized ablation approaches adapted to the patient’s cardiac abnormalities. Success rates have been documented to be between 79 and 94% in larger studies and effective ablation improves survival and freedom from any VA. Ablation should be considered early in the treatment plan and availability may be improved by interhospital collaboration with highly experienced VA intervention centers.

ST segment depression in hypertensive patients: A comparison of exercise test versus Holter ECG

Introduction: This study compared ST segment depression (ST depression) during cycle ergometry (ergometry) versus simultaneous 24-hour ambulatory blood pressure measurement and electrocardiogram recording (24-h ABPM/ECG) during everyday life. Methods: In a German multicenter study, ergometry and 24-h ABPM/ECG records of 239 hypertensive patients were retrospectively analyzed. ST depression was defined as an ST segment depression (1 mm limb or chest recordings V1 to V6) in an incremental cycle ergometry, or 1 mm in the 24-h ABPM/ECG recording under everyday conditions. Blood pressure parameters at the onset of ST depression in the context of the respective method were compared. Results: 18 patients had ST depression only in ergometry (group B), 23 had ST depression only during 24-h ABPM/ECG monitoring (group C) and 28 patients had ST depression with both methods (group D). Group A had no ST depression with any method. In group D, at the onset of ST depression with 24-h ABPM/ECG investigation, all parameters except diastolic blood pressure were significantly lower compared with the corresponding parameters at the onset of ST depression with ergometry (systolic blood pressure: 148 ± 19 vers 188 ± 35 mmHg, p × 0.001; heart rate: 93 ± 12 vs 120 ± 21 beat/min, p < 0.0001; double product: 13,714 ± 2315 vs 22,992 ± 3,985 mmHg/min), p < 0.0001). Conclusion: ST depressions during everyday life detected by 24-h ABPM/ECG are characterized by a substantially lower triggering threshold for blood pressure level parameters compared with ergometry. The two methods detecting ischemia do not replace but complement each other.

An impaired renal function and advanced heart failure represent independent predictors of the incidence of malignant ventricular arrhythmias in patients with an implantable cardioverter/defibrillator for primary prevention

AIMS Malignant ventricular arrhythmias and inappropriate therapies represent unsolved problems in patients with implantable cardioverter/defibrillator (ICD) for primary prevention. This study focuses on the incidence of such therapies and thereby seeks to identify new predictors of adverse events to enhance risk stratification. METHODS AND RESULTS Ninety-four consecutive patients with mild-to-moderate heart failure (NYHA II-III) and depressed left ventricular function (≤35%) were followed for 34 ± 20 months. Two hundred and ninety-one malignant ventricular arrhythmias were documented in 51 patients (54%). Eighteen patients (19%) received inappropriate ICD therapies (e.g. atrial fibrillation, sinus tachycardia, etc.). Patients with malignant arrhythmia (1.34 ± 0.44 vs. 1.16 ± 0.4 mg/dL, P = 0.017) and patients suffering from inappropriate ICD therapies (1.54 ± 0.48 vs. 1.2 ± 0.38 mg/dL; P = 0.007) revealed a significantly worse renal function before ICD implantation than participants without any therapy. An increased serum creatinine at baseline (2 vs. 1 mg/dL; odds ratio (OR) 3.96; P = 0.02; 95% CI: 1.2-13.04) and NHYA class III compared with II (OR: 2.96; P = 0.02; 95% CI: 1.16-7.48) represent strong and independent predictors for the occurrence of ventricular arrhythmias. Moreover, an impaired renal function is identified as an independent risk factor for inappropriate therapies (OR: 5.6; P = 0.004; 95% CI: 1.72-18.22). CONCLUSION An impaired renal function and advanced heart failure before ICD implantation for primary prevention are identified as independent predictors for the incidence of appropriate ICD interventions. With regard to current guidelines and economical aspects, patients suffering from an impaired renal function or advanced heart failure seem to benefit most from ICD therapy.

Treatment of persistent atrial fibrillation using phased radiofrequency ablation technology.

A novel ablation system consisting of a duty-cycled phased radiofrequency generator and multielectrode mapping and ablation catheters has been introduced to provide ablation therapy in patients with symptomatic atrial fibrillation (AF). Contiguous lesions may be created using anatomically designed ablation catheters maneuvered under fluoroscopic guidance without the use of a 3D electroanatomic mapping system. In addition to pulmonary vein isolation using a circular, decapolar ablation catheter, an ablation strategy targeting complex fractionated atrial electrograms can be performed using two supplemental multiarray catheters specifically designed for ablation at the left atrial septum and within the left atrial body. Procedural times for treating persistent AF using phased radiofrequency are reported as being between 2 and 2.5 h. Freedom from AF ranges between 33 and 75% after a single procedure, which is comparable to other conventional ablation approaches (utilizing electroanatomic mapping). Additional studies in larger patient numbers are needed to understand the long-term maintenance of results and potential adverse effects of the technology.

Significance of Wedensky Modulation testing in the evaluation of non-invasive risk stratification for ventricular tachyarrhythmia in patients with coronary artery disease and implantable cardioverter-defibrillator

Objective: Evaluation of the significance of the Wedensky Modulation (WM) examination for ventricular tachyarrhythmias (VT) in patients with coronary artery disease and implantable cardioverter-defibrillator therapy (ICD). Design: Prospective, single-centre study conducted from 2004 to 2006. Setting: University of Bonn, Department of Medicine – Cardiology, Bonn, Germany. Patients: 37 consecutive patients with coronary artery disease receiving an ICD for primary or secondary prevention. Main outcome measures: Correlation of a positive WM-Index (WMI) with established non-invasive Holter parameter, the occurrence of VT after ICD implantation with regard to primary or secondary prevention, and inducibility of VT during electrophysiological (EP) studies. Results: The WMI was positive in 15 patients (67 (SD 8) years, 31% (SD 12%) EF) and showed significant correlation with heart rate variability (standard deviation of normal to normal intervals (SDNN): 143 (SD 80) ms vs 102 (SD 29) ms, p = 0.04, r = 0.45; total power (TP). 11 885 (SD 19 674) ms2 vs 2229 (SD 1779) ms2, p = 0.03, r = 0.384; very low frequency component (VLF): 2777 (SD 3039) ms2 vs 1184 (SD 565) ms2, p = 0.03; low frequency component (LF): 2955 (SD 5734) ms2 vs 468 (SD 725) ms2, p = 0.05, r = 0.375; high frequency component (HF): 4885 (SD 9939) ms2 vs 382 (SD 609) ms2, p = 0.05, r = 0.315) and turbulence (turbulence onset (TO): −0.002 (SD 0.008) vs +0.005 (SD 0.01), p = 0.05, r = 0.301; turbulence slope (TS): 3.4 (SD 3.1) vs 1.7 (SD 1.5), p = 0.04, r = 0.419). The positive predictive value of the WMI considering the inducibility of VT during EP testing was 100%. Those patients who received an ICD for primary prevention showed a higher WMI (p = 0.049) than the secondary prevention group. With respect to the occurrence of adequate VT episodes, a negative WM test result demonstrated a negative predictive value of 95%. Conclusion: The data presented show that the WM-Index predicts VT inducibility during EP testing and indicates a high negative predictive value regarding the occurrence of VT.

Implantation of Left Ventricular Epicardial Leads in Cardiosurgical Patients with Impaired Cardiac Function–A Worthwhile Procedure in Concomitant Surgical Interventions?

BACKGROUND Cardiac resynchronization therapy (CRT) by means of multisite biventricular pacing is an effective therapeutic option for the treatment of severe heart failure. The present study estimates how many open heart-surgery patients could benefit from the implantation of permanent left ventricular (LV) pacing leads. After routine preoperative screening, epicardial electrodes were implanted in selected patients. Lead performance and outcomes were investigated. METHODS Primarily, 1059 patients were retrospectively investigated with regard to LV function, left bundle branch block and QRS duration. Afterwards, suitable patients were identified and epicardial electrodes [Medtronic 5071 (ME) or Enpath (EP)] were implanted during concomitant procedures. Mean follow-up time was 6.3 ± 5.5 months. RESULTS The retrospective study showed that 24 patients (2.3%) could potentially profit from CRT. After routine preoperative screening for CRT-responders, 22 patients (1.6%) were identified who finally received epicardial leads. No complications occurred. Acute capture threshold was 0.9 ± 0.4 V (ME, n = 17) and 0.5 ± 0.2 V (EP, n = 5). While leads in 18 patients were implanted as an upgrade to an existing pacemaker or implantable cardioverter-defibrillator (ICD) technologies (Group B), 4 patients underwent prophylactic implantation with no device attached (Group A). CRT-ICDs were implanted at follow-up in 3 Group A patients (75%). In Group B patients, the QRS duration decreased (from 189 ± 35 ms to 152 ± 16 ms, p < 0.02) and their postoperative mean NYHA functional class improved significantly (2.2 ± 0.5 versus 2.8 ± 0.6). CONCLUSION A small group of cardiac surgery patients may benefit from LV-lead implantation during concomitant procedures. A protocol for responder identification is useful. Existing devices should be upgraded to CRT systems. As CRT-ICD implantation is frequent, the additional costs and time are justified.

Heart rate variability in patients suffering from structural heart disease and decreased AV-nodal conduction capacity. Insights into the formation of heart rate variability.

Eingeschränkte Oszillationen der Herzfrequenz, d. h. eine reduzierte Herzfrequenzvariabilität (HRV), gehen mit einem erhöhten Mortalitätsrisiko bei Patienten mit struktureller Herzerkrankung einher. Weiterhin zeigt dieses Patientenkollektiv häufig Störungen des Erregungsleitungssystems. In wie weit bei Patienten mit struktureller Herzerkrankung und solchen Erregungsleitungsstörungen eine Analyse der Herzfrequenzvariabilität sinnvoll und aussagekräftig erscheint, wurde bisher noch nicht untersucht. In der vorliegenden Studie untersuchten wir bei 20 konsekutiven Patienten, die einer elektrophysiologischen Untersuchung zugeführt wurden, neben der HRV das genaue Zustandekommen der HRV und den Einfluss kardialer Parameter auf die HRV. Mittels eines 5 stufigen Protokolls untersuchten wir bei unseren Patienten die Zeitund Frequenzspektrum-Parameter der HRV: 1: Ruheaufnahme bei normalem Sinusrhythmus (SR1). 2: AAI-Stimulation (AAI) mit einer Frequenz von 15% oberhalb der intrinsischen Herzfrequenz. 3: VAT-Stimulation (VAT) mit einem sehr kurzen AV-Intervall. 4: DDD-Stimulation (DDD) mit einer Stimulationsfrequenz von 15% oberhalb des intrinsischen Rhythmus und einem kurzen AV-Intervall. 5: Abschlussaufnahme bei normalem Sinusrhythmus (SR2). Jede Aufnahmephase dauerte 600s und wurde in Rückenlage durchgeführt. Patienten mit höhergradigen AV-Blockierungen (II° oder III°) wurden ausgeschlossen. Die HRV-Parameter während der Phasen SR1 und SR2 zeigten keine Unterschiede. Bei funktionellem Ausschluss des AV-Knotens (VAT-Modus) war die HRV verglichen mit der SR1-Phase nicht unterschiedlich. Unter funktionellem Ausschluss des Sinusknotens (AAI-Modus) zeigte sich ein signifikanter Unterschied für SDNN und r-MSSD (p < 0,001). Auch waren die Phasen AAI und VAT signifikant verschieden (p < 0,001). Die HRV während DDD war ebenso kleiner im Vergleich zu AAI (p < 0,04). Das Vorliegen einer strukturellen Herzerkrankung, die Einschränkung der linksventrikulären Pumpleistung von < 50% sowie das Vorliegen einer nicht anhaltenden ventrikulären Tachykardie im Langzeit-EKG hatte keinen signifikanten Einfluss auf die HRV in den unterschiedlichen Phasen der Stimulation. Der mittlere Wenckebachpunkt der Patienten mit struktureller Herzerkrankung war größer als der nicht strukturell Herzkranken (437 ms vs. 350 ms, p = 0,05). Veränderungen des Wenckebachpunkts waren nicht mit einer Veränderung der HRV korreliert (p = ns). Die Herzfrequenzvariabilität ist im Wesentlichen durch die Impulsformationen des Sinusknotens bestimmt. Eine Leitungsvariabilität des AV-Knotens existiert zwar, ist jedoch unter klinischen Bedingungen vernachlässigbar. Daher kann bei Patienten mit struktureller Herzerkrankung mit oder ohne dem Vorliegen einer moderaten AV-Knoten-Überleitungsstörung die Herzfrequenzvariabilität als Teil der nicht invasiven Risikostratifikation bestimmt und bewertet werden. Attenuation of the oscillation of the heart rate, i. e. heart rate variability (HRV), is associated with an increased risk for mortality in patients with structural heart disease. Many of these patients also suffer from conduction disturbances, e. g. AV-nodal conduction delays. Whether the calculation of HRV in those patients is recommendable has not been investigated yet. Therefore, we conducted a study consisting of 20 consecutive patients in order to determine the formation of HRV, the influence of structural heart disease, the presence of a nonsustained ventricular tachycardia (VT), and a reduced ejection fraction (EF) on the HRV parameters during an elective electrophysiologic study. Time and frequency domain analysis were conducted during a period of 600 s each. We performed a special protocol consisting of five different “pacing” periods: 1) recording of normal sinus rhythm (SR1); 2) atrial pacing with a rate 15% higher than the intrinsic heart rate; 3) ventricular pacing triggered by atrial activation (VAT, with a short AV-delay of 80 ms); 4) AV-sequential pacing with an atrial rate 15% higher than the intrinsic heart rate and a very short AV delay of 80 ms (DDD); 5) normal sinus rhythm (SR2). Only patients with normal AVnodal conduction or with AV-block I° were included. The influence of a structural heart disease as well as a non-sustained VT on Holter ECG and a depressed EF on HRV parameters were analyzed using a multivariate analysis. All patients were lying in a supine position. Blood pressure was measured continuously and the frequency of breathing was controlled. No differences in HRV between the two sinus rhythm periods SR1 versus SR2 could be detected. Neither SR1 vs VAT showed a significant difference for SDNN and r-MSSD. In contrast, HRV during SR1 compared to AAI, and HRV during VAT compared to AAI were significantly different (p < 0.001). When comparing HRV during DDD, which should be zero, and AAI, we found a significantly lower SDNN and r-MSSD (1.2 ms vs 4 ms, p < 0.04). The presence of structural heart disease, a non-sustained ventricular tachycardia, a depressed ejection fraction of less than 0.50 did not reveal a significant influence on the HRV parameters (multivariate analysis). The mean Wenckebach in patients with structural heart disease tended to be greater (437 ms vs 350 ms, p = 0.05); an increase in theWenckebach was not correlated to a change in HRV parameters (p = ns). Heart rate variability derived from consecutive RR-intervals is predominantly caused by periodicity in sinusnode impulse formation. A conduction variability of the AV-node exists, but is very low. The presence of a structural heart disease, a non-sustained ventricular tachycardia on Holter ECG, as well as a depressed ejection fraction of less than 0.50 showed no significant influence on the HRV parameters. Therefore, one can apply the calculation of heart rate variability for risk stratification in patients suffering from structural heart disease and moderate AV-nodal conduction disturbances.