Corinna Brunckhorst

Catheter Ablation in Patients With Multiple and Unstable Ventricular Tachycardias After Myocardial Infarction Short Ablation Lines Guided by Reentry Circuit Isthmuses and Sinus Rhythm Mapping

Background—Extensive lines of radiofrequency (RF) lesions through infarct (MI) can ablate multiple and unstable ventricular tachycardias (VTs). Methods for guiding ablation that minimize unnecessary RF applications are needed. This study assesses the feasibility of guiding RF line placement by mapping to identify a reentry circuit isthmus. Methods and Results—Catheter mapping and ablation were performed in 40 patients (MI location: inferior, 28; anterior, 7; and both, 5) with an electroanatomic mapping system to measure the infarct region and ablation lines. The initial line was placed in the MI region either through a circuit isthmus identified from entrainment mapping or a target identified from pace mapping. A total of 143 VTs (42 stable, 101 unstable) were induced. An isthmus was identified in 25 patients (63%; 5 with only stable VTs, 5 with only unstable VTs, and 15 with both VTs). Inducible VTs were abolished or modified in 100% of patients when the RF line included an isthmus compared with 53% when RF had to be guided by pace mapping (P =0.0002); those with an isthmus identified received shorter ablation lines (4.9±2.4 versus 7.4±4.3 cm total length, P =0.02). During follow-up, spontaneous VT decreased markedly regardless of whether an isthmus was identified. VT stability and number of morphologies did not influence outcome. Conclusions—A 4- to 5-cm line of RF lesions abolishes all inducible VTs in more than 50% of patients. Less ablation is required if a reentry circuit isthmus is identified even when multiple and unstable VTs are present.

Treatment of Arrhythmogenic Right Ventricular Cardiomyopathy/Dysplasia: An International Task Force Consensus Statement

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Predictors of adverse outcome in patients with arrhythmogenic right ventricular dysplasia/cardiomyopathy: long term experience of a tertiary care centre

Objective: To investigate the predictors for adverse clinical outcome in patients with arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C) during long term follow up. Methods: 61 patients with ARVD/C were studied to assess the impact of family history, clinical findings, surface ECG parameters, echocardiographic findings, and electrophysiological findings on clinical outcome. The prevalence of these risk factors were compared in two patient groups: group A (patients with adverse clinical outcome: sudden cardiac death, death from heart failure, or heart transplant) and group B (survivors excluding patients who received a heart transplant). Results: Mean age at first diagnosis was 44 (14) years. The mean follow up duration was 55 (47) months. Ten patients (16%) died during follow up. The cause of death of eight of these patients was probably arrhythmic. Two patients died of advanced heart failure. Five patients underwent heart transplantation because of terminal heart failure. Risk factors significantly associated with adverse outcome were history of congestive heart failure (p < 0.001), the presence of left ventricular involvement on echocardiography (p < 0.001), left atrial dilatation (p < 0.05), prolonged PR duration (p < 0.01), prolonged QRS in V1 (p < 0.05), and bundle branch block (p < 0.05). In multivariate analysis, history of congestive heart failure and presence of left ventricular involvement were identified as independent risk predictors for an adverse outcome. Conclusions: Congestive heart failure and left ventricular involvement are independently associated with adverse outcome in patients with ARVD/C during long term follow up.

Relationship of Slow Conduction Detected by Pace-Mapping to Ventricular Tachycardia Re-Entry Circuit Sites After Infarction

OBJECTIVES This study sought to characterize the relationship of conduction delays detected by pace-mapping, evident as a stimulus to QRS interval (S-QRS) delay >or=40 ms, to ventricular tachycardia (VT) re-entry circuit isthmuses defined by entrainment and ablation. BACKGROUND Areas of slow conduction and block in old infarcts cause re-entrant VT. METHODS In 12 patients with VT after infarction, pace-mapping was performed at 890 sites. Stimulus to QRS intervals were measured and plotted in three-dimensional reconstructions of the left ventricle. Conduction delay was defined as >or=40 ms and marked delay as >80 ms. The locations of conduction delays were compared to the locations of 14 target areas, defined as the region within a radius of 2 cm of a re-entry circuit isthmus. RESULTS Pacing captured at 829 sites; 465 (56%) had no S-QRS delay, 364 (44%) had a delay >or=40 ms, and 127 (15%) had a delay >80 ms. Sites with delays were clustered in 14 discrete regions, 13 of which overlapped target regions. Only 1 of the 14 target regions was not related to an area of S-QRS delay. Sites with marked delays >80 ms were more often in the target (52%) than sites with delays 40 to 80 ms (29%) (p < 0.0001). CONCLUSIONS Identification of abnormal conduction during pace-mapping can be used to focus mapping during induced VT to a discrete region of the infarct. Further study is warranted to determine if targeting regions of conduction delay may allow ablation of VT during stable sinus rhythm without mapping during VT.

Cardiac contractility modulation by non-excitatory currents: Studies in isolated cardiac muscle

Myocardial contractility can be altered using voltage clamp techniques by modulating amplitude and duration of the action potential resulting in enhanced calcium entry in the cell of isolated muscle strips (Non‐Excitatory Currents; NEC). Extracellular electrical stimuli delivered during the absolute refractory period (Cardiac Contractility Modulation; CCM) have recently been shown to produce inotropic effects in‐vivo.

Feasibility study of the use of the TandemHeart® percutaneous ventricular assist device for treatment of cardiogenic shock

Background: The mortality of cardiogenic shock (CGS) remains high despite currently available pharmacological and mechanical treatment options. The standard of care in medically refractory situations has been the insertion of an intra‐aortic balloon pump. The purpose of this study was to investigate the feasibility, safety, and hemodynamic impact of the TandemHeart® percutaneous left ventricular assist device (pVAD) in CGS. Methods: Thirteen patients from five centers in the US with the diagnosis of CGS were enrolled in the study. Hemodynamic measurements, including cardiac index (CI), mean arterial pressure (MAP), pulmonary capillary wedge pressure (PCWP), and central venous pressure (CVP) were performed presupport, during support and after device removal. Patients were monitored for 6 months. Results: The pVAD was successfully implanted in all 13 patients, with duration of support averaging 60 ± 44 hr. During support, CI increased from 2.09 ± 0.64 at baseline to 2.53 ± 0.65 (P = 0.02), MAP increased from 70.6 ± 11.1 to 81.7 ± 14.6 (P = 0.01), PCWP decreased from 27.2 ± 12.2 to 16.5 ± 4.8 (P = 0.01), and CVP from 12.9 ± 3.7 to 12.6 ± 3.6 (P = NS). Ten patients survived to device explant, 6 of whom were bridged to another therapy. Seven patients survived to hospital discharge and were all alive at 6 months. The two most common adverse events were distal leg ischemia (n = 3) and bleeding from the cannulation site (n = 4). Conclusion: The TandemHeart® PTVA System may be a useful complementary treatment for patients with CGS, especially as a bridge to another treatment. Further study is needed to definitively establish safety and efficacy.

Different Prognostic Value of Functional Right Ventricular Parameters in Arrhythmogenic Right Ventricular Cardiomyopathy/Dysplasia

Background—The value of standard 2-dimensional transthoracic echocardiographic parameters for risk stratification in patients with arrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVC/D) is controversial. Methods and Results—We investigated the impact of RV fractional area change (FAC) and tricuspid annulus plane systolic excursion (TAPSE) for the prediction of major adverse cardiovascular events (MACE) defined as the occurrence of cardiac death, heart transplantation, survived sudden cardiac death, ventricular fibrillation, sustained ventricular tachycardia, or arrhythmogenic syncope. Among 70 patients who fulfilled the 2010 ARVC/D Revised Task Force Criteria and underwent baseline transthoracic echocardiography, 37 (53%) patients experienced MACE during a median follow-up period of 5.3 (interquartile range, 1.8–9.8) years. Average values for FAC, TAPSE, and TAPSE indexed to body surface area (BSA) decreased over time (P=0.03 for FAC, P=0.03 for TAPSE, and P=0.01 for TAPSE/BSA, each versus baseline). In contrast, median RV end-diastolic area increased (P=0.001 versus baseline). Based on the results of Kaplan–Meier estimates, the time between baseline transthoracic echocardiography and experiencing MACE was significantly shorter for patients with FAC <23% (P<0.001), TAPSE <17 mm (P=0.02), or right atrial short axis/BSA ≥25 mm/m2 (P=0.04) at baseline. A reduced FAC constituted the strongest predictor of MACE (hazard ratio, 1.08 per 1% decrease; 95% confidence interval, 1.04–1.12; P<0.001) on bivariable analysis. Conclusions—This long-term observational study indicates that TAPSE and dilation of right-sided cardiac chambers are associated with an increased risk for MACE in patients with ARVC/D with advanced disease and a high risk for adverse events. However, FAC is the strongest echocardiographic predictor of adverse outcome in these patients. Our data advocate a role for transthoracic echocardiography in risk stratification in patients with ARVC/D, although our results may not be generalizable to lower-risk ARVC/D cohorts.

Diagnosis of Sleep-Related Breathing Disorders by Visual Analysis of Transthoracic Impedance Signals in Pacemakers

Background—Minute ventilation sensors of cardiac pacemakers measure ventilation by means of transthoracic impedance changes between the pacemaker case and the electrode tip. We investigated whether this technique might detect sleep-related breathing disorders. Methods and Results—In 22 patients, analog waveforms of the transthoracic impedance signal measured by the pacemaker minute ventilation sensor over the course of a night were visualized, scored for apnea/hypopnea events, and compared with simultaneous polysomnography. Analysis of transthoracic impedance signals correctly identified the presence or absence of moderate to severe sleep apnea (apnea/hypopnea index, AHI >20 h−1) in all patients (receiver operating characteristics, ROC=1.0). The ROC for AHI scores of ≥5 h−1 and ≥10 h−1 showed an area under the curve of 0.95, P<0.005, and 0.97, P<0.0001, respectively. Accuracy over time assessed by comparing events per 5-minute epochs was high (Cronbach &agr; reliability coefficient, 0.85; intraclass correlation, 0.73). Event-by-event comparison within ±15 seconds revealed agreement in 81% (&kgr;, 0.77; P<0.001). Conclusions—Detection of apnea/hypopnea events by pacemaker minute ventilation sensors is feasible and accurate compared with laboratory polysomnography. This technique might be useful to screen and monitor sleep-related breathing disorders in pacemaker patients.

Electrophysiological findings in patients with isolated left ventricular non-compaction.

AIMS Patients with isolated left ventricular non-compaction (IVNC) are at high risk for developing ventricular tachyarrhythmias. However, no analysis of invasive electrophysiological (EP) findings in these patients has yet been performed. METHODS AND RESULTS We performed a retrospective analysis of EP findings in 24 patients with IVNC. Ventricular tachyarrhythmias were inducible in nine patients; of these, two patients had sustained monomorphic ventricular tachycardia (VT) and two patients had ventricular fibrillation. No specific electrocardiographic or echocardiographic finding was predictive of VT inducibility. Three of the 9 patients with inducible VT experienced ventricular tachyarrhythmias during the follow-up of 61.4+/-50 months, whereas no tachyarrhythmias or sudden deaths were noted in 12 patients without inducible VT during the follow-up of 30+/-19 months (3 patients in the latter group were lost to follow-up). Supraventricular tachyarrhythmias were inducible in seven patients. CONCLUSION Our present study provides the first comprehensive analysis of EP findings in patients with IVNC. Ventricular and supraventricular arrhythmias can readily be induced in these patients, whereas the inducibility of a sustained monomorphic VT is relatively low. Further studies including long-term follow-up are required to investigate the role of EP testing for arrhythmic risk stratification in these patients.

Electrocardiographic changes in early recognition of Fabry disease

Background Fabry disease (FD) is an inherited X-chromosomal lysosomal storage disease resulting in intracellular storage of globotriaosylceramide. Cardiac involvement is most frequently manifested as left ventricular hypertrophy (LVH). However, patients with FD may also have various conduction abnormalities before LVH develops. The present study was designed to analyse early conduction abnormalities on baseline ECG of patients with FD and to investigate their diagnostic value. Methods and results Baseline electrocardiographic (ECG) and echocardiographic measurements of patients with FD (n=30) were compared with those of heart rate and age-matched healthy individuals (n=50). The PQ-interval (131±18 vs 155±20 ms, p<0.000001) and the QRS width (83±11 vs 90±9 ms, p<0.05) were significantly shorter and repolarisation dispersion was more pronounced in patients with FD (QTc dispersion: 66±32 vs 40±24 ms, p<0.001, Tpeak−Tend dispersion: 56±20 vs 37±16 ms, p<0.0005). Moreover, P-wave duration was significantly shorter (74±16 vs 105±14 ms, p<0.000001) in FD and accounted predominantly for the shortening of the PQ-interval. P-wave duration showed a 92% sensitivity and 80% specificity for the diagnosis of FD. Conclusions P-wave duration, PQ-interval and QRS width are shorter and repolarisation dispersion more pronounced in patients with FD compared with heart rate and age-matched controls. The significant shortening of the PQ-interval in FD occurs because of a marked shortening of the P-wave duration, which in itself demonstrated a high sensitivity and specificity for early detection and treatment of this disease.