Ultra-high-frequency ECG volumetric and negative derivative epicardial ventricular electrical activation pattern.

From precordial ECG leads, the conventional determination of the negative derivative of the QRS complex (ND-ECG) assesses epicardial activation. Recently we showed that ultra-high-frequency electrocardiography (UHF-ECG) determines the activation of a larger volume of the ventricular wall. We aimed to combine these two methods to investigate the potential of volumetric and epicardial ventricular activation assessment and thereby determine the transmural activation sequence. We retrospectively analyzed 390 ECG records divided into three groups-healthy subjects with normal ECG, left bundle branch block (LBBB), and right bundle branch block (RBBB) patients. Then we created UHF-ECG and ND-ECG-derived depolarization maps and computed interventricular electrical dyssynchrony. Characteristic spatio-temporal differences were found between the volumetric UHF-ECG activation patterns and epicardial ND-ECG in the Normal, LBBB, and RBBB groups, despite the overall high correlations between both methods. Interventricular electrical dyssynchrony values assessed by the ND-ECG were consistently larger than values computed by the UHF-ECG method. Noninvasively obtained UHF-ECG and ND-ECG analyses describe different ventricular dyssynchrony and the general course of ventricular depolarization. Combining both methods based on standard 12-lead ECG electrode positions allows for a more detailed analysis of volumetric and epicardial ventricular electrical activation, including the assessment of the depolarization wave direction propagation in ventricles.

Novel ultra-high-frequency electrocardiogram tool for the description of the ventricular depolarization pattern before and during cardiac resynchronization.

INTRODUCTION: The present study introduces a new ultra-high-frequency 14-lead electrocardiogram technique (UHF-ECG) for mapping ventricular depolarization patterns and calculation of novel dyssynchrony parameters that may improve the selection of patients and application of cardiac resynchronization therapy (CRT). METHODS: Components of the ECG in sixteen frequency bands within the 150 to 1000 Hz range were used to create ventricular depolarization maps. The maximum time difference between the UHF QRS complex centers of mass of leads V1 to V8 was defined as ventricular electrical dyssynchrony (e-DYS), and the duration at 50% of peak voltage amplitude in each lead was defined as the duration of local depolarization (Vd). Proof of principle measurements was performed in seven patients with left (left bundle branch block) and four patients with right bundle branch block (right bundle branch block) before and during CRT using biventricular and His-bundle pacing. RESULTS: The acquired activation maps reflect the activation sequence under the tested conditions. e-DYS decreased considerably more than QRS duration, during both biventricular pacing (-50% vs -8%) and His-bundle pacing (-77% vs -13%). While biventricular pacing slightly increased Vd, His-bundle pacing reduced Vd significantly (+11% vs -36%), indicating the contribution of the fast conduction system. Optimization of biventricular pacing by adjusting VV-interval showed a decrease of e-DYS from 102 to 36 ms with only a small Vd increase and QRS duration decrease. CONCLUSIONS: The UHF-ECG technique provides novel information about electrical activation of the ventricles from a standard ECG electrode setup, potentially improving the selection of patients for CRT and application of CRT.

The relationship between ECG predictors of cardiac resynchronization therapy benefit.

INTRODUCTION: Cardiac resynchronization therapy (CRT) is an effective treatment that reduces mortality and improves cardiac function in patients with left bundle branch block (LBBB). However, about 30% of patients passing the current criteria do not benefit or benefit only a little from CRT. Three predictors of benefit based on different ECG properties were compared: 1) "strict" left bundle branch block classification (SLBBB); 2) QRS area; 3) ventricular electrical delay (VED) which defines the septal-lateral conduction delay. These predictors have never been analyzed concurrently. We analyzed the relationship between them on a subset of 602 records from the MADIT-CRT trial. METHODS & RESULTS: SLBBB classification was performed by two experts; QRS area and VED were computed fully automatically. High-frequency QRS (HFQRS) maps were used to inspect conduction abnormalities. The correlation between SLBBB and other predictors was R = 0.613, 0.523 and 0.390 for VED, QRS area in Z lead, and QRS duration, respectively. Scatter plots were used to pick up disagreement between the predictors. The majority of SLBBB subjects- 295 of 330 (89%)-are supposed to respond positively to CRT according to the VED and QRS area, though 93 of 272 (34%) non-SLBBB should also benefit from CRT according to the VED and QRS area. CONCLUSION: SLBBB classification is limited by the proper setting of cut-off values. In addition, it is too "strict" and excludes patients that may benefit from CRT therapy. QRS area and VED are clearly defined parameters. They may be used to optimize biventricular stimulation. Detailed analysis of conduction irregularities with CRT optimization should be based on HFQRS maps.

Ventricular dyssynchrony assessment using ultra-high frequency ECG technique.

PURPOSE: The aim of this proof-of-concept study is to introduce new high-dynamic ECG technique with potential to detect temporal-spatial distribution of ventricular electrical depolarization and to assess the level of ventricular dyssynchrony. METHODS: 5-kHz 12-lead ECG data was collected. The amplitude envelopes of the QRS were computed in an ultra-high frequency band of 500-1000 Hz and were averaged (UHFQRS). UHFQRS V lead maps were compiled, and numerical descriptor identifying ventricular dyssynchrony (UHFDYS) was detected. RESULTS: An electrical UHFQRS maps describe the ventricular dyssynchrony distribution in resolution of milliseconds and correlate with strain rate results obtained by speckle tracking echocardiography. The effect of biventricular stimulation is demonstrated by the UHFQRS morphology and by the UHFDYS descriptor in selected examples. CONCLUSIONS: UHFQRS offers a new and simple technique for assessing electrical activation patterns in ventricular dyssynchrony with a temporal-spatial resolution that cannot be obtained by processing standard surface ECG. The main clinical potential of UHFQRS lies in the identification of differences in electrical activation among CRT candidates and detection of improvements in electrical synchrony in patients with biventricular pacing.

Heart rate variability analysed by Poincaré plot in patients with metabolic syndrome.

INTRODUCTION: The SD1 and SD2 indexes (standard deviations in two orthogonal directions of the Poincaré plot) carry similar information to the spectral density power of the high and low frequency bands but have the advantage of easier calculation and lesser stationarity dependence. METHODS: ECG signals from metabolic syndrome (MetS) and control group patients during tilt table test under controlled breathing (20 breaths/minute) were obtained. SD1, SD2, SDRR (standard deviation of RR intervals) and RMSSD (root mean square of successive differences of RR intervals) were evaluated for 31 control group and 33 MetS subjects. RESULTS: Statistically significant lower values were observed in MetS patients in supine position (SD1: p=0.03, SD2: p=0.002, SDRR: p=0.006, RMSSD: p=0.01) and during tilt (SD2: p=0.004, SDRR: p=0.007). CONCLUSION: SD1 and SD2 combining the advantages of time and frequency domain methods, distinguish successfully between MetS and control subjects.

Home monitoring of implantable cardioverter-defibrillators: interpretation reliability of the second-generation "IEGM Online" system.

AIMS: Intracardiac electrograms (IEGMs) are essential for the assessment of implantable cardioverter-defibrillator (ICD) function. The Biotronik Home Monitoring systems transmit an 'IEGM Online' that is shorter than the full-length programmer IEGM due to technical constrains. The aim of this study was to evaluate the accuracy of the physician's classification of the underlying rhythm based on the second-generation IEGM Online. METHODS AND RESULTS: In total, 1533 patients treated with single- and dual-chamber ICDs and cardiac resynchronization therapy defibrillators were enrolled at 67 investigational sites and followed for 15 months. The investigators classified the rhythm shown in IEGM Online as ventricular tachycardia, ventricular fibrillation, atrial fibrillation, other supraventricular tachyarrhythmia, oversensing due to lead failure, T-wave oversensing, or other rhythm. At the next in-office follow-up, the investigators classified independently the rhythm seen in the corresponding programmer IEGM. The two rhythm classifications were compared thereafter. Both IEGM Online and programmer IEGM were available in 2099 arrhythmic or oversensing events, of which 146 (7.0%) were classified as other rhythm or artefacts and were excluded as inconclusive or atypical. The remaining 1953 events, affecting 352 patients (23.0%), were classified correctly in 1803 cases (92.3%). The accuracy of rough rhythm classification as ventricular, supraventricular, or oversensing was 97.2%. CONCLUSION: The Lumax and IEGM Online HD Evaluation study demonstrates that remote IEGM analysis is reasonably accurate in a remote monitoring system that transmits shorter IEGM than the full-length programmer IEGM for the sake of frequent, fully automatic data transmission.

Causes of death and heart pathology in pacemaker or implantable cardioverter-def ibrillator patients who died in hospital.

UNLABELLED: 83 pacemaker (PM)/14 implantable cardioverter-defibrillator (ICD) autopsied patients, predominantly males, deceased 4.0±3.0/2.8±2.5 years after implantation in hospital. Coronary artery disease was most frequent. Its consequences were more severe in ICD patients. Sclerotic and rheumatic heart changes were present in older PM patients group only. The immediate cause of death was mostly of cardiac etiology. Relatively short implant-death interval should be explained by rather great part of non-cardiac causes of death in hospitalised patients. KEYWORDS: pacemakers - implantable cardioverter - defibrillators-causes of death - heart pathology - autopsy.

Histological findings around electrodes in pacemaker and implantable cardioverter-defibrillator patients: comparison of steroid-eluting and non-steroid-eluting electrodes.

AIMS: To analyse histological findings surrounding the electrodes in pacemaker/implantable cardioverter-defibrillator (PM/ICD) patients. To compare histology around steroid-eluting and non-steroid ventricular pacing electrodes. METHODS AND RESULTS: In autopsied PM/ICD patients histopathological findings around the electrodes were determined. Seventy patients were studied, PM(58), ICD(12), mean age 75.1 ± 9.3 years. The implantation-death interval was 4.0 ± 3.3 years. Most causes of death were cardiac (PM 52%, ICD 58%). The majority of atrial electrodes were attached to the endocardium and most ventricular electrodes were found in the myocardium (P ≤ 0.001). The maximum thickness of the fibrous electrode sheath was greatest for the ICD ventricular electrodes. Some electrodes were covered with fibrin thrombi and granulation tissue, most frequently in the ICD ventricular electrodes. The fibrous sheath usually contained chronic inflammatory cells and in some cases particles of foreign material, foreign body giant cells, and haematogenous pigment. The tissue around steroid-eluting ventricle PM electrodes was compared with the tissue around the non-steroid-eluting ventricle PM electrodes; granulation tissue, foreign material, giant cells being found more frequently around the steroid-eluting electrodes. The fibrous sheath was slightly thinner in the steroid-eluting electrodes. The histology around four coronary sinus electrodes was described. CONCLUSIONS: Atrial electrodes were attached more superficially to the endocardium while PM and ICD ventricular electrodes were more frequently embedded in the myocardium. The electrodes were covered by a connective tissue sheath as a result of thrombus organization. This process persisted most frequently around ICD ventricular electrodes. Only borderline differences were found between the histological findings around steroid-eluting and non-steroid-eluting PM ventricular electrodes.

Use of a novel transfer function to reduce repolarization interval hysteresis.

BACKGROUND: Cardiac repolarization is assessed by the QT interval on the surface electrocardiogram and varies with the heart rate. Standard QT corrections (QTc) do not account for the lag in QT change following a change in heart rate (QT hysteresis). Our group has developed and tested a transfer function (TRF) model to assess the effectiveness of a dynamic model of QT/RR coupling in eliminating hysteresis. METHODS: We studied three groups: group I, healthy volunteers (n = 23, 41 ± 17 years); group II, hypertensive patients (n = 25, 45 ± 11 years); and group III, patients in a predominately paced rhythm (n = 5, 75 ± 6 years). To vary the heart rate, either exercise bicycling in the supine position (groups I and II) or manipulation of the pacemaker parameters (group III) was done. We then compared a dynamic TRF model with a model based on weighted averages of previous RR intervals. Two parameters were tested: root mean square (RMS) of the error signal between measured and computed QT and the elimination of hysteretic loops. RESULTS: TRF-based measurements eliminated hysteresis in 22/23 (95%) group I patients, 21/25 (84%) group II patients, and 4/5 (80%) group III patients. When hysteresis elimination was not complete, the QT drift that followed RR intervals was different before and after bicycling (100 ms). In these patients, the corresponding QT interval did not significantly change during this period. The TRF model was found superior to the other tested models with respect to both analyzed parameters (RMS and hysteresis elimination). CONCLUSION: The TRF model limited QT hysteresis in healthy, hypertensive, and pacemaker-dependent patients. In addition, an important finding of QT drift in patients with hypertension was identified. With further study in these and other diseased states, the TRF model may improve our ability to measure accurately cardiac repolarization and to determine arrhythmia risk.

Does the resynchronization therapy lead to reduction of symptoms and to improvement of left ventricular functions in patients with chronic heart failure?

AIM: To evaluate the therapeutic effect of resynchronization in patients with chronic heart failure who are symptomatic despite adequate pharmacological medication. SAMPLE AND METHODOLOGY: 118 patients with chronic heart failure, mostly dilated cardiomyopathy and ischaemic heart disease, with depressed systolic function, decreased left ventricular ejection fraction (LVEF) and left bundle branch block wide QRS complex, underwent implantation of the biventricular system between the years 2000-2006. We assessed changes in the NYHA functional class, hemodynamic parameters acquired during right heart catheterization, the maximum oxygen consumption during stress spiroergometric examination, as well as echocardiographic parameters. RESULTS: A statistically significant improvement was found in the NYHA functional class (from 2.8 +/- 0.4 to 2.3 +/- 0.5 after 3 m, p < 0,001 and to 2.5 +/- 0.6 after 12 m, p < 0,01 respectively), as well as an increase in the maximum oxygen consumption during spiroergometric examination (VO2 max from 14.1 +/- 3.1 ml/kg/min to 15.3 +/- 3.1 ml/kg/ min, p < 0,001 and to 15.3 +/- 2.5 ml/kg/min, p = NS respectively). In regard to hemodynamic parameters, there were increases in cardiac output and cardiac index after three months. After 12 months the change was not statistically significant (CO from 3.9 +/- 1 l/min to 4.2 +/- 0.9 l/min, p < 0,05, and to 4.1 +/- 0.9 l/min, p = NS, CI from 2 +/- 0.5 l/kg/min to 2.2 +/- 0.4 l/kg/min, p < 0,05, and to 2.1 +/- 0.4 l/kg/min, p = NS). Mean pulmonary artery pressure, as well as pulmonary capillary wedge pressure was reduced after 3, as well as after 12 months to a statistically significant degree (MPA from 29.1 +/- 11.5 mm Hg to 23.9 +/- 10.3 mm Hg, p< 0,001, and to 24.9 +/- 11.8 mm Hg, p < 0,01 respectively, and PCWP from 19.9 +/- 9.5 mm Hg to 15.2 +/- 9.2 mm Hg, p < 0,01, and to 15.6 +/- 9 mm Hg, p < 0,01 respectively). In regard to echocardiographic parameters, there was an increase in LVEF, a reduction in the end-diastolic diameter of the left ventricle, as well as a statistically significant reduction in severity of mitral regurgitation after 3, as well as 12 months (LVEF from 20.5 +/- 5.3%, to 23 +/- 6.5%, p < 0,001, and to 24.5 +/- 8%, p < 0,001, LVEDD from 69 +/- 9 mm to 68 +/- 9 mm, p < 0.01 and to 65 +/- 12 mm, p< 0.01 respectively, mitral regurgitation from 2.2 +/- 0.8 to 1.9 +/- 0.8, p< 0.001, and to 2 +/- 0.8, p < 0.001. CONCLUSIONS: In patients with chronic heart failure, resynchronization therapy leads to reduced symptoms, reduction in dyspnea and to improvements in cardiac performance due to increase in the systolic function of the left ventricle and hemodynamic changes.

Usefulness of left ventricle dyssynchrony assessment before cardiac resynchronization implantation.

BACKGROUND: A number of trials have demonstrated the effect of cardiac resynchronization therapy (CRT) on functional improvement and reversed left ventricle remodeling. Meeting contemporary guidelines approximately 30- 40% of patients do not respond to CRT (non-responders). AIM: To quantify the predictive ability of basal QRS width and basal echocardiographic parameters of left ventricle contraction dyssynchrony in our group of CRT patients. To compare effectiveness of these parameters assessment in patients with ischemic (iCMP) and non-ischemic cardiomyopathy (niCMP) and with sinus rhythm (SR) and atrial fibrillation (AF). PATIENTS AND METHODS: 194 patients after successful introduction of CRT device were evaluated. Evaluation of NYHA function class, QRS width and echocardiographic parameters including parameters of left ventricle contraction dyssynchrony (SPWMD: septal-to-posterior wall motion delay, Ts-sep-lat: time interval between maximum of systolic movement of septum and lateral wall using tissue Doppler imaging, IVMD: interventricular mechanical delay) performed before implantation and 3 months after implantation of CRT device. RESULTS: Responder (improved in NYHA class after CRT) rate was 61%. SR patients showed higher benefit compared to AF patients (responder rate 63% vs. 52%, p<0.05). Narrowing of QRS width after CRT was observed only in responders. SPWMD and Ts-sep-lat decreased after CRT in all subgroups. SPWMD dyssynchrony (SPMWD > or = 130 ms) reduction after CRT was more expressed in niCMP population. Ts-sep-lat dyssynchrony (Ts-sep-lat > or = 65 ms) reduction after CRT was more expressed in SR patients. IVMD (IVMD > or = 60 ms) remained unchanged in average, but significant decrease was observed in responders and significant increase in non-responders. QRS width, SPWMD and Ts-sep-lat showed moderate sensitivity but poor specificity to predict CRT benefit. QRS width > or = 150 ms in niCMP patients showed higher sensitivity to predict CRT effect compared to iCMP patients (91%, 65% respectively). IVMD showed poor sensitivity but good specificity to predict CRT benefit. IVMD in SR patients (compared to AF patients) showed higher specificity to predict CRT effect (90%, 63% respectively). CONCLUSION: None of tested left ventricle contraction dyssynchrony parameters showed good sensitivity and specificity to predict CRT benefit. QRS width as a predictor factor was more beneficial in non-ischemic patients and IVMD in sinus rhythm patients.

QT/RR Coupling and Gender Differences.

Data provided by THEW was used to test QT gender differences. Three QT/RR models were used during analysis: a transfer function model (TRF), a model based on exponential weighting of RR intervals (EXP), and an EXP model with additive direct coupling with RR intervals (EXPDC). Data from 81 men and 73 women was analyzed.Women have a significantly higher QTc (p<10(-6)), steeper Gain(L) (QT/RR slope, gain for slow RR variability, p<0.01), faster τ (QT adaptation, p<0.05), higher Gain(F) (gain for fast RR variability, immediate change of QT, p<0.05) and higher QT random variability (p<0.05).The higher prevalence of arrhythmias in women, given by longer QTc, is compensated to some extent by a higher level of Gain(F) and faster τ. The proarrhythmic influence of drugs may originate in a change of Gain(L), Gain(F) or τ without any change in QTc.

Autopsy and clinical context in deceased patients with implanted pacemakers and defibrillators: intracardiac findings near their leads and electrodes.

AIMS: To evaluate intracardiac findings near leads and causes of death in pacemaker/defibrillator patients. METHODS AND RESULTS: Special autopsy was performed on 78 patients deceased in a hospital. Age at death was 77.9 +/- 10.0, implantation-death interval 4.0 +/- 3.3 years, ventricular leads n = 78, and atrial leads n = 21. Thrombi along leads in brachiocephalic vein/upper caval vein (BV/UCV) were found in 22 (7), in right atrium (RA) in 11 (8), and in right ventricle (RV) in 11 cases. Bipolar lead rings were fixed by fibrous tissue in 43 (4) cases. Connective tissue bridges and tunnels were found in BV/UCV in 44 (13), in RA in 17 (15), and in RV in 68 cases, with a length of 0.2-12.0 cm. Right ventricular leads in tricuspidal orifice were fixed by fibrous tissue in 11 and penetrating chordae in 25 cases. Main causes of death were: heart failure in 35, pulmonary embolism in 9, and myocardial infarction in 11 cases. CONCLUSION: We have found (i) thrombi on ventricular/atrial leads in 33/48%, (ii) bipolar lead rings fixed by fibrous tissue in 68/22%, (iii) connective tissue bridges or tunnels in ventricle/atrium in 87/71%, and (iv) ventricular leads fixed to valve or penetrating chordae in 46% of patients. We do recommend caution when extracting leads.

Short-term effects of cardiac resynchronization therapy on sleep-disordered breathing in patients with systolic heart failure.

OBJECTIVES: We evaluated the short-term effect of cardiac resynchronization therapy (CRT) on sleep apnea in patients with systolic heart failure. BACKGROUND: Sleep-disordered breathing is common in patients with left ventricular systolic dysfunction. METHODS: Twelve patients (mean [+/-SE] age, 59.6+/-7.8 years; mean left ventricular ejection fraction, 28.0+/-2.8%) with an implanted atrial-synchronized biventricular pacemaker for the treatment of left ventricular systolic dysfunction were selected and studied. Each subject underwent polysomnography on 3 consecutive nights with CRT on the first night, CRT off the second night, and CRT on the third night. Echocardiography was performed prior to each polysomnogram. RESULTS: The central sleep event index (ie, the number of central sleep apneas [CSAs] and hypopneas per hour of sleep) score was lower with CRT compared to that without CRT (mean central sleep event index score with CRT on, 6.9+/-1.7 events per hour of sleep; mean central sleep event index score with CRT off, 14.3+/-2.9 events per hour of sleep; mean central sleep event index score with CRT on, 8.1+/-1.5 events per hour of sleep; p<0.001). Similarly, the cumulative duration of central sleep events (the number of minutes per hour of sleep during CRT) was one half that observed without CRT (CRT on, 2.8+/-0.7 min per hour of sleep; CRT OFF 6.2+/-1.2 min per hour of sleep; CRT ON 3.1+/-0.7 min per hour of sleep; p<0.001). There was a significant correlation between mitral regurgitant volume and central sleep event index on all three nights (r>or=0.77; p<0.01). CONCLUSIONS: CRT reduces CSA severity in the short term. This reduction correlated significantly with the CRT-mediated reduction of mitral regurgitation.