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  • 1
    Electronic Resource
    Electronic Resource
    Acute Results of Transvenous Cryoablation of Supraventricular Tachycardia (Atrial Fibrillation, Atrial Flutter, Wolff-Parkinson-White Syndrome, Atrioventricular Nodal Reentry Tachycardia) (2002)
    Oxford, UK : Blackwell Science Inc
    Journal of cardiovascular electrophysiology 13 (2002), S. 0 
    Details
    ISSN: 1540-8167
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Transvenous Cryoablation for SVT. Introduction: Radiofrequency (RF) catheter ablation currently is used for treatment of cardiac arrhythmias. Although the success rate is high for almost all supraventricular tachycardias (SVT), this technique has some drawbacks, especially when pulmonary veins (PV) are targeted for treatment of atrial fibrillation (AF). Additionally, new techniques for isolation of the PVs have the drawback that they can be used only for PV isolation and not for routine treatment of other SVTs. The aim of this study was to report on the safety and efficacy of a new cryoablation system for treatment of all SVTs. Methods and Results: Forty-nine patients with SVT (38 men; age 48 years, range 23–76) were enrolled in the study. Five patients were withdrawn from the study before they underwent cryoablation. The remaining 44 patients were treated with cryoablation (22 AF, 15 atrial flutter, 3 accessory pathway, 2 AV nodal reentrant tachycardia, 1 AV junction ablation for permanent AF, 1 atrial tachycardia). Cryoablation was performed with the CryoCorTM cryoablation system, which uses a precooling system and N2O as a refrigerant. The number of freezes applied varied according to the index arrhythmia treated. Successful isolation of PVs was performed in 20 of (96%) 21 AF patients and 53 of 55 veins. The overall acute success was 98% (43/44). Fifty-three PVs were isolated (2.5/patient). The success rate was 100% (23/23) for right-sided procedures. The average and nadir temperatures reached in right-sided and left-sided procedures were −77°C and −80°C and −75°C and −78°C, respectively. No acute PV stenosis was seen. Conclusion: This novel cryoablation system appears to be safe and can successfully treat different types of SVTs, including AF. Isolation of PVs is possible without producing stenosis. Despite the high blood flow in the right atrial isthmus and PVs, bidirectional conduction block can be achieved.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1540-8167.2002.01082.x
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  • 2
    Electronic Resource
    Electronic Resource
    Spontaneous Episode of Polymorphic Ventricular Tachycardia in a Patient with Intermittent Brugada Syndrome (2001)
    Oxford, UK : Blackwell Science Inc
    Journal of cardiovascular electrophysiology 12 (2001), S. 0 
    Details
    ISSN: 1540-8167
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1540-8167.2001.01094.x
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  • 3
    Electronic Resource
    Electronic Resource
    Patients with Persistent Atrial Fibrillation Taking Oral Verapamil Exhibit a Lower Atrial Frequency on the ECG (2002)
    Oxford, UK : Blackwell Publishing Ltd
    Annals of noninvasive electrocardiology 7 (2002), S. 0 
    Details
    ISSN: 1542-474X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Background: While there is agreement that verapamil attenuates the AF- induced refractory period shortening when given before AF induction, controversy exists regarding its effects when given after the onset of persistent AF. This study aimed to compare atrial fibrillatory frequency obtained from the surface ECG in patients with persistent atrial fibrillation (AF) with oral verapamil treatment to those without this treatment.Methods and Results: Surface ECG recordings were performed in 57 patients (34 male, 23 female, mean age 59 ± 11 years) with persistent AF (〉 7 days). The frequency content of the fibrillatory baseline was quantified using digital signal processing (filtering, QRST complex averaging and subtraction. Fourier transformation). In 27 patients with verapamil treatment (120 or 240 mg/day for at least 7 days) mean fibrillatory frequency measured 6.4 ± 0.2 Hz, compared to 7.0 ± 0.4 Hz (P = 0.012) in 30 patients without verapamil. In a subset of 20 randomly selected patients (10 with, 10 without verapamil treatment) a 24-hour Holter ECG recording was performed and fibrillatory frequency determined at 4 PM, 10 PM, 4 AM, and 10 AM. While there was a significant frequency reduction in the verapamil treated patients at night (P = 0.011), it remained constant over time in the other patients.Conclusion: In patients with persistent AF, fibrillatory frequency assessed by spectral analysis of the surface ECG is lower in patients taking verapamil. A.N.E. 2002;7(2):92–97
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1542-474X.2002.tb00148.x
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  • 4
    Electronic Resource
    Electronic Resource
    Frequency Measures Obtained from the Surface Electrocardiogram in Atrial Fibrillation Research and Clinical Decision-Making (2003)
    350 Main Street , Malden , MA 02148-5018 , USA , and 9600 Garsington Road , Oxford OX4 2DQ , UK . : Blackwell Science Inc
    Journal of cardiovascular electrophysiology 14 (2003), S. 0 
    Details
    ISSN: 1540-8167
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Introduction: Frequency analysis of fibrillation (FAF) and time-frequency analysis (TFA) were developed recently in order to quantify atrial electrical remodeling in atrial fibrillation (AF) from the surface ECG. This article describes the experience with these two different frequency analysis techniques in consecutive AF patients and discusses possible applications in AF research and clinical decision-making. Methods and Results: Baseline 2-minute, high-gain, high-resolution ECG recordings using three bipolar leads were obtained from 80 consecutive patients with AF lasting 〉24 hours. A power spectrum was obtained using Fourier analysis following spatiotemporal QRST cancellation. The dominant fibrillatory rate (in fibrillations per minute [fpm]) was derived (FAF). Stability of the instantaneous fibrillatory rate measured in overlapping 1-second segments was expressed as the segment proportion with consecutive rate differences 〈6 fpm (TFA). An adequate power spectrum that could be submitted for determination of fibrillatory rate was obtained in all patients. Dominant atrial rates ranged between 288 and 534 fpm and showed a high correlation (R = 0. 878–0.911, P 〈 0.001) when assessed from the three different leads. The average instantaneous fibrillatory rate was inversely related with its stability (R =−0.417, P 〈 0.001). It was closely related with the dominant fibrillatory rate obtained from FAF (R = 0.948, P 〈 0.001). A literature review revealed that pharmacologic or electrical cardioversion and AF pace termination success rates were highly dependent on fibrillatory rate. Conclusion: Atrial fibrillatory rate and its variability can be reliable obtained from the surface ECG in AF patients. These parameters exhibit a significant interindividual variability allowing individual quantification of the atrial electrical remodeling process and might prove useful for predicting therapy efficacy. (J Cardiovasc Electrophysiol, Vol. 14, pp. S154-S161, October 2003, Suppl.)
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1540.8167.90305.x
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  • 5
    Electronic Resource
    Electronic Resource
    Catheter Ablation of Ventricular Tachycardia by Intramyocardial Injection of Ethanol in an Animal Model of Chronic Myocardial Infarction (2004)
    350 Main Street , Malden , MA 02148-5018 , USA , and 9600 Garsington Road , Oxford OX4 2DQ , UK . : Blackwell Science Inc
    Journal of cardiovascular electrophysiology 15 (2004), S. 0 
    Details
    ISSN: 1540-8167
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Introduction: Direct injection of ethanol into myocardium has been shown to create large, well-demarcated lesions with transmural necrosis in normal ventricular myocardium and in regions of healed myocardial infarction. The aim of this study was to investigate the effects of direct ethanol injection on the inducibility of ventricular tachycardia (VT) in an animal model of chronic myocardial infarction. Methods and Results: Eight sheep with reproducibly inducible VT underwent an electrophysiologic study 139 ± 65 days after myocardial infarction. Noncontact mapping was used to analyze induced VT. Fifteen different VTs were targeted for catheter ablation. Ablation was achieved by catheter-based intramyocardial injection of a mixture of 96% ethanol, glycerine, and iopromide (ratio 3:1:1). Direct intramyocardial ethanol injection resulted in noninducibility of any VT 20 minutes after ablation in 7 of 8 animals. Four of 5 animals with initially successful ablation remained noninducible for any VT at follow-up study at least 2 days after the ablation procedure. Microscopic examination revealed homogeneous lesions with interstitial edema, intramural hemorrhage, and myofibrillar degeneration at the lesion border. The lesions were well demarcated from the surrounding tissue by a border zone of neutrophilic infiltration. Conclusion: Catheter ablation of VT by direct intramyocardial injection of ethanol during the chronic phase of myocardial infarction is feasible. It may be a useful tool for catheter ablation when the area of interest is located deep intramyocardially or subepicardially or when a more regional approach requires ablation of larger amounts of tissue. (J Cardiovasc Electrophysiol, Vol. 15, pp. 332-341, March 2004)
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1540-8167.2004.03409.x
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  • 6
    Electronic Resource
    Electronic Resource
    Right and Left Ventricular Activation Sequence in Patients with Heart Failure and Right Bundle Branch Block:
A Detailed Analysis Using Three-Dimensional Non-Fluoroscopic Electroanatomic Mapping System (2005)
    350 Main Street , Malden , MA 02148-5018 , USA , and 9600 Garsington Road , Oxford OX4 2DQ , UK . : Blackwell Science Inc
    Journal of cardiovascular electrophysiology 16 (2005), S. 0 
    Details
    ISSN: 1540-8167
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Introduction: Recently, right bundle branch block (RBBB) was proved to be an important predictor of mortality in heart failure (HF) patients as much as left bundle branch block (LBBB). We characterized endocardial right ventricular (RV) and left ventricular (LV) activation sequence in HF patients with RBBB using a three-dimensional non-fluoroscopic electroanatomic contact mapping system (3D-Map) in order to provide the electrophysiological background to understand whether these patients can benefit from cardiac resynchronization therapy (CRT). Methods and Results: Using 3D-Map, RV and LV activation sequences were studied in 100 consecutive HF patients. Six of these patients presented with RBBB QRS morphology. The maps of these patients were analyzed and compared post hoc with those of the other 94 HF patients presenting with LBBB. Clinical and hemodynamic profile was significantly worse in RBBB group compared to LBBB. Patients with RBBB showed significantly longer time to RV breakthrough (P 〈 0.001), longer activation times of RV anterior and lateral regions (P 〈 0.001), and longer total RV endocardial activation time (P 〈 0.02) compared to patients with LBBB. Time to LV breakthrough was significantly shorter in patients with RBBB (P 〈 0.001), while total and regional LV endocardial activation times were not significantly different between the two groups. Conclusions: Degree of LV activation delay is similar between HF patients with LBBB and RBBB. Moreover, patients with RBBB have larger right-sided conduction delay compared to patients with LBBB. The assessment of these electrical abnormalities is important to understand the rationale for delivering CRT in HF patients with RBBB.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1540-8167.2005.40777.x
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  • 7
    Electronic Resource
    Electronic Resource
    Echocardiographic and Electrocardiographic Predictors for Atrial Fibrillation Recurrence Following Cardioversion (2003)
    350 Main Street , Malden , MA 02148-5018 , USA , and 9600 Garsington Road , Oxford OX4 2DQ , UK . : Blackwell Science Inc
    Journal of cardiovascular electrophysiology 14 (2003), S. 0 
    Details
    ISSN: 1540-8167
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Introduction: Identification of suitable candidates for cardioversion currently is not based on individual electrical and mechanical atrial remodeling. Therefore, this study analyzed the meaning of atrial fibrillatory rate obtained from the surface ECG (as a measure of electrical remodeling) and left atrial size (as measure of mechanical remodeling) for prediction of early atrial fibrillation (AF) recurrence following cardioversion. Methods and Results: Forty-four consecutive patients (26 men and 18 women, mean age 62 ± 11 years, no antiarrhythmic medication at baseline) with persistent AF were studied. Fibrillatory rate was obtained from high-gain, high-resolution surface ECG using digital signal processing (filtering, QRST subtraction, Fourier analysis) before electrical cardioversion. Univariate and multivariate regression analysis revealed larger systolic left atrial area (Beta = 0.176, P = 0.031) obtained by precardioversion echocardiogram from the apical four-chamber view and higher atrial fibrillatory rate (Beta = 0.029, P = 0.021) to be independent predictors for AF recurrence (n = 13). Stratification based on the regression equation (electromechanical index [EMI]= 0.176 systolic left atrial area + 0.029 fibrillatory rate − 17.674) allowed identification of groups at low, intermediate, or high risk. No patient with an EMI 〈 −1.85 had early AF recurrence, as opposed to 78% with an EMI 〉 −0.25. Intermediate results (40% recurrence rate) were obtained when the calculated EMI ranged between −1.85 and −0.25 (P 〈 0.001). Conclusion: Fibrillatory rate obtained from the surface ECG and systolic left atrial area obtained by echocardiography may predict early AF recurrence in patients with persistent AF. These parameters might be useful in identifying candidates with a high likelihood of remaining in sinus rhythm after cardioversion. (J Cardiovasc Electrophysiol, Vol. 14, pp. S162-S165, October 2003, Suppl.)
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1540.8167.90306.x
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  • 8
    Electronic Resource
    Electronic Resource
    T Wave Alternans Does not Assess Arrhythmic Risk in Patients with Brugada Syndrome (2004)
    350 Main Street , Malden , MA 02148 , USA , and 9600 Garsington Road , Oxford OX4 2DQ , UK . : Blackwell Science Inc
    Annals of noninvasive electrocardiology 9 (2004), S. 0 
    Details
    ISSN: 1542-474X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Background: Brugada syndrome is associated with a risk for sudden death, but the arrhythmic risk in an individual Brugada syndrome patient is difficult to predict. Pathologic changes in the early repolarization phase of the ventricular action potential probably constitute part of the arrhythmogenic substrate in Brugada syndrome. Microvolt T wave alternans (TWA) assesses dynamic beat-to-beat changes in repolarization and has been suggested as a marker for repolarization-related sudden death. We therefore tested whether TWA is an indicator for arrhythmias in Brugada syndrome with a focus on right precordial ECG leads. Methods: We assessed TWA in nine symptomatic, inducible patients with established Brugada syndrome and in seven healthy controls. TWA was assessed at rest and during exercise using both standard methods and an algorithm that assesses TWA in the early ST segment and the right precordial leads. Results: None of the Brugada patients developed TWA in this study irrespective of analysis at rest or during exercise, neither using standard methods nor when the early ST segment was included in the analysis. When the early ST segment was included in the analysis, nonsustained TWA was found in three out of seven, and sustained TWA in one control. Conclusion: T wave alternans is not an appropriate test to detect arrhythmic risk in patients with Brugada syndrome.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1542-474X.2004.92541.x
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  • 9
    Electronic Resource
    Electronic Resource
    Pilot Study: Noninvasive Monitoring of Oral Flecainide's Effects on Atrial Electrophysiology during Persistent Human Atrial Fibrillation Using the Surface Electrocardiogram (2005)
    350 Main Street , Malden , MA 02148 , USA , and 9600 Garsington Road , Oxford OX4 2XG , UK . : Blackwell Publishing, Inc.
    Annals of noninvasive electrocardiology 10 (2005), S. 0 
    Details
    ISSN: 1542-474X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Background: The relation between flecainide's plasma level and its influence on human atrial electrophysiology during acute and maintenance therapy of atrial fibrillation (AF) is unknown. Therefore, this study determined flecainide plasma levels and atrial fibrillatory rate obtained from the surface ECG during initiation and early maintenance of oral flecainide in patients with persistent lone AF and assessed their relationship. Methods and Results: In 10 patients (5 males, mean age 63 ± 14 years, left atrial diameter 46 ± 3 mm) with persistent lone AF, flecainide was administered as a single oral bolus (day 1) followed by 200–400 mg/day (days 2–5). The initial 300 mg flecainide bolus resulted in therapeutic plasma levels in all patients (range 288–629 ng/ml) with no side effects. Flecainide plasma levels increased on day 3 and remained stable thereafter. Day 5 plasma levels were lower (508 ± 135 vs 974 ± 276 ng/ml, P = 0.009) in patients with daily mean flecainide doses of 200 mg compared to patients with higher maintenance doses. Fibrillatory rate obtained from the surface electrocardiogram measuring 378 ± 17 fpm at baseline was reduced to 270 ± 18 fpm (P 〈 0.001) after the flecainide bolus but remained stable thereafter. Fibrillatory rate reduction was independent of flecainide plasma levels or clinical variables. Conclusion: A 300 mg oral flecainide bolus is associated with electrophysiologic effects that are not increased during early maintenance therapy in persistent human lone AF. In contrast to drug plasma levels, serial analysis of fibrillatory rate allows monitoring of individual drug effects on atrial electrophysiology.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1542-474X.2005.05616.x
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  • 10
    Electronic Resource
    Electronic Resource
    Response of Atrial Fibrillatory Activity to Carotid Sinus Massage in Patients with Atrial Fibrillation (2001)
    Oxford, UK : Blackwell Futura Publishing, Inc.
    Pacing and clinical electrophysiology 24 (2001), S. 0 
    Details
    ISSN: 1540-8159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: BOLLMANN, A., et al.: Response of Atrial Fibrillatory Activity to Carotid Sinus Massage in Patients with Atrial Fibrillation. In some cases carotid sinus massage (CSM) may induce AF, whereas it may terminate AF in others. The purpose of this study was to investigate the influence of CSM on atrial fibrillatory frequency using spectral analysis of the surface ECG. Continuous ECG recordings were made in 19 patients (12 men, 7 women, mean age 61 ± 11 years) with AF. Unilateral CSM was performed in the standard fashion to one randomized bifurcation of the carotid artery at a time. Ventricular rate and fibrillatory frequency were assessed in 30-second ECG segments at baseline and during CSM. The frequency content of the fibrillatory baseline was quantified using digital signal processing (filtering, subtraction of averaged QRST complexes, and Fourier transformation). CSM resulted in a relative change in fibrillatory frequency of 4.5 ± 3.9% (range 0%–13%). In 8 (42%) patients an increase in fibrillatory frequency was found (6.4 ± 0.5 vs 6.8 ± 0.5 Hz, P = 0.012). In 9 (47%) patients a decrease in fibrillatory frequency occurred (6.5 ± 0.8 vs 6.1 ± 0.8 Hz, P = 0.008) without AF termination. The remaining two patients showed no change in fibrillatory frequency. CSM on the contralateral side after 2 minutes produced fibrillatory frequency changes in the same direction in all patients with a good reproducibility in its magnitude (r = 0.59, P = 0.05). Calcium channel blockers were more frequently used (78% vs 25%, P = 0.044) in patients with a decrease in fibrillatory frequency compared to patients with a frequency increase. There were no significant changes in ventricular rate during CSM. In conclusion, two different responses of atrial fibrillatory frequency to CSM were found. This might explain why CSM may facilitate AF induction in some cases and AF termination in others. Calcium channel blocker treatment may prevent an increase in fibrillatory frequency provoked by CSM suggesting a blunted electrical remodeling process.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1460-9592.2001.01363.x
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