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Haran Burri

Publications and source records attributed to Haran Burri.

At least 19 recordsLinked to original sources
PubMed2006

Utility of the surface ECG before VDD pacemaker implantation.

BACKGROUND: VDD pacemakers may be implanted in the setting of atrioventricular block with preserved sinus function. Their main advantage over DDD pacemakers is use of a single lead. However, low-amplitude atrial electrograms (EGMs) recorded from the free-floating atrial electrode may lead to undersensing. There is currently no way of predicting EGM amplitude prior to implantation and to thus identify candidates who may be safely implanted with a VDD pacemaker. AIM: We sought to investigate whether the P-wave amplitude measured on the standard surface ECG correlates with the atrial EGM amplitude measured by the single-pass lead at implantation. METHODS: Data on 122 patients implanted with a VDD pacemaker at our institution were reviewed. Atrial EGM amplitudes measured at implantation by the single-pass lead were correlated with the maximal P-wave amplitude on the surface ECG recorded just prior to implantation. RESULTS: There was a highly significant correlation between the maximal P-wave amplitude on the surface ECG and the atrial EGM (Pearson's correlation 0.313, P<0.001). Multivariate analysis showed that maximal P-wave amplitude was independently associated with atrial EGM amplitude (p=0.003). For the overall population, an EGM amplitude of <0.9 mV was present in only 11/122 (9%) cases. An atrial EGM amplitude of <0.9 mV was found in 10/69 (14%) of patients with a maximal surface P-wave < or =0.1 mV but only in 1/53 (2%) of those with >0.1 mV (p=0.023). CONCLUSION: Low-amplitude atrial EGMs at implantation are found in a minority of patients with single-pass leads. However, patients with a maximal surface P-wave amplitude of >0.1 mV are especially unlikely to have a low atrial EGM amplitude and may be good candidates for a VDD pacemaker.

Aged↗
PubMed2006

Identifying far-field superior vena cava potentials within the right superior pulmonary vein.

BACKGROUND: Far-field extra-pulmonary vein (PV) potentials originating from the left atrial appendage and adjacent left atrium have been identified within the left PVs, but no systematic study of extra-PV potentials within the right superior PV (RSPV) has been described. OBJECTIVES: The purpose of this study was to prospectively analyze extra-PV contributions to RSPV potentials. METHODS: In a consecutive, prospective series of 114 patients (96 men and 18 women; 56 +/- 10 years) undergoing electrophysiologically guided ostial PV isolation, residual potentials recorded with a circular mapping catheter in the RSPV after ostial isolation were analyzed. Their extra-PV origin was validated by mapping a site with identical timing (in sinus rhythm or atrial fibrillation) within the adjacent superior vena cava (SVC) where, in sinus rhythm, local pacing (until threshold amplitude) concealed the residual potential within the stimulus artifact because of very short activation timing. The timing of residual potentials with respect to surface ECG P-wave onset was measured and compared with the earliest timing of ablated RSPV potentials. RESULTS: Residual low-amplitude (mean 0.29 +/- 0.17 mV, range 0.07-0.65 mV) extra-PV potentials were recorded from the anterior and superior aspect of the RSPV in 3.6 +/- 1 bipoles in 26 (23%) patients (all men, 51 +/- 10 years) with a timing from sinus P-wave onset of 17 +/- 12 ms (range 0-40 ms) vs 52 +/- 9 ms (range 35-70 ms) for the earliest RSPV potential (P <.001, t-test). Extra-PV potentials all originated from the posterior aspect of the SVC. The SVC potential was identified during ongoing atrial fibrillation in eight patients and later confirmed in sinus rhythm. An extra-PV potential of SVC origin could be identified by timing earlier than 30 ms from onset of the sinus P wave, with sensitivity of 92%, specificity 100%, positive predictive value 100%, and negative predictive value 89%. CONCLUSION: Extra-PV potentials of right-sided SVC origin were recorded within the RSPV in 23% of patients and can be identified with high sensitivity and specificity by a timing within 30 ms of sinus P-wave onset. Recognizing these potentials can avoid unnecessary additional ablation and possibly PV stenosis or phrenic paralysis.

Adult↗
PubMed2006

Beat-to-beat variations of the electrocardiogram in survivors of sudden death without structural heart disease.

AIM: We sought to determine whether survivors of sudden death without structural heart disease have beat-to-beat electrocardiographic (ECG) characteristics at the microvolt and at the millisecond level that differ from normal subjects. METHODS: We studied patients at our implantable cardioverter defibrillator clinic who had been resuscitated from ventricular fibrillation with no evidence of underlying structural heart disease. Continuous 10-minute high-resolution unfiltered digital surface ECGs at 1000-Hz sampling rate were acquired in these subjects and in a group of healthy volunteers. We then analyzed different parameters of beat-to-beat variations in duration, amplitudes and vectors of the QRS complex, and the T wave using a locally developed program (Comparative Analysis of ECGs, Vectocardiograms, and their Interpretation with Auto-Reference to the patient) and compared them between the 2 groups. RESULTS: Thirteen patients (7 men; age, 46 +/- 16 years) were studied. Standard ECGs were unremarkable in 7 patients and suggestive of Brugada syndrome in the 6 others. The control group consisted of 23 age- and sex-matched subjects (13 men; age, 41 +/- 10 years). Although the QRS parameters showed only few differences between the 2 groups, there were several differences in parameters evaluating repolarization. CONCLUSION: High-resolution ECGs show distinct beat-to-beat variations in parameters of repolarization in survivors of sudden death without structural heart disease, as compared with normal subjects. These findings may reflect increased electrical instability and should be evaluated for stratifying arrhythmic risk in asymptomatic individuals.

Adult↗
PubMed2006

Simulation of anteroseptal myocardial infarction by electrocardiographic filters.

BACKGROUND: Most electrocardiographs have high-pass filters that may be used to attenuate baseline wander due to respiratory artifact. However, the T wave also has low-frequency components and may be distorted by these filters. Our aim was to investigate the effect of high-pass filters on the ST segment. METHODS: Twenty healthy volunteers had a standard 12-lead electrocardiogram recorded using a Bard EP Labsystem (Bard Inc, Lowell, Mass) at different high-pass filter settings (0.05, 0.1, 0.5, and 1.0 Hz). ST-segment elevation or depression was measured using digital calipers at each setting and the electrocardiogram classified as being either normal or suggestive of myocardial infarction. RESULTS: There were no significant differences in ST elevation between 0.05- and 0.1-Hz filter settings. However, at 0.5 and 1.0 Hz, there was significant ST elevation in the right precordial leads and ST depression in the inferior leads. The greatest changes were observed in V2, with an ST elevation of 0.13 +/- 0.08 and 0.18 +/- 0.09 mV at 0.5 and 1.0 Hz, respectively (P < .0001 compared with 0.05 Hz). All tracings were considered normal at 0.05- and 0.1-Hz filter settings. However, at 0.5 and 1.0 Hz, 60% and 100%, respectively, of tracings were suggestive of anteroseptal myocardial infarction. Signal distortion was attributed to phase nonlinearities of the filters. CONCLUSIONS: High-pass filters may distort the ST segment and simulate anteroseptal myocardial infarction. These filters should comply with current standards if used on electrocardiographs and be used with caution. In case of doubt, the tracings should be compared with minimally filtered recordings.

Adult↗
PubMed2006

Prevention of implantable defibrillator shocks by cognitive behavioral therapy: a pilot trial.

BACKGROUND: Although psychological stress is known to favor ventricular arrhythmic events, there is no evidence that stress management intervention decreases ventricular electrical instability in implantable cardioverter-defibrillator (ICD) patients. The aim of the study was to determine whether cognitive behavioral therapy (CBT) results in a decrease of arrhythmic events requiring ICD intervention through an improvement in sympathovagal balance. METHODS: Of 253 consecutive ICD patients (age 59 +/- 10 years, 64 men), 70 were randomly assigned to CBT (n = 35) or conventional medical care (n = 35). Measures of heart rate variability, psychological well-being, and quality of life were assessed at baseline, 3 months, and 1 year. The primary outcome was appropriate ICD shock. RESULTS: Although, it was not statistically different, the number of patients requiring shocks was less in the CBT group than in the conventional treatment group. At 3 months, among patients without antiarrhythmic drugs, none of the subjects in the CBT group had experienced arrhythmic events requiring ICD intervention, as compared with 4 in the control group (P < .05). At 12 months, there was no difference in the number of arrhythmic events requiring therapy between the CBT group versus the control group. Among heart rate variability indexes, daytime pNN 50 and nocturnal SDNN improved significantly in the CBT group, as compared with the control group. CONCLUSIONS: By decreasing anxiety and possibly improving sympathovagal balance, cognitive behavior therapy may decrease the propensity for ventricular arrhythmias in ICD patients. However, these effects appear to be limited over time.

Arrhythmias, Cardiac↗
PubMed2006

Echocardiography and patient selection for cardiac resynchronization therapy: a critical appraisal.

Echocardiography has been the focus of growing interest for improving patient selection for cardiac resynchronization therapy in order to reduce the number of nonresponders. Various techniques have been described for assessing dyssynchrony, using standard echocardiography (pulsed-wave Doppler and M-mode echocardiography), tissue Doppler imaging, and other imaging modes such as three-dimensional echocardiography. This article provides an overview of the technical and practical aspects of these different techniques and discusses the current evidence for optimizing patient selection by echocardiography.

Cardiac Pacing, Artificial↗
PubMed2006

Ventricular mechanical dyssynchrony and resynchronization therapy in heart failure: a new indication for Fourier analysis of gated blood-pool radionuclide ventriculography.

In patients with decreased left ventricular ejection fraction and conduction disease, ventricular mechanical dyssynchrony has been demonstrated. To date, resynchronization by biventricular pacing is increasingly used since it improves ventricular function and exercise capacity in patients with heart failure. To optimize and evaluate the effect of resynchronization therapy and to identify patients who may benefit from biventricular pacing the assessment of left ventricular synchronicity is essential. Therefore, a non-invasive and reproducible technique to obtain information on ventricular synchrony is clinically valuable. In this review, the technical background and the role of phase analysis of gated blood-pool nuclear ventriculography in the assessment of ventricular mechanical synchrony, especially in heart failure patients subjected to biventricular pacing, will be discussed.

Cardiac Pacing, Artificial↗
PubMed2006

Optimization of device programming for cardiac resynchronization therapy.

Cardiac resynchronization therapy may lead to remarkable improvement in clinical status in selected patients with heart failure. However, approximately 20-30% of patients may not respond to this treatment. One of the reasons for this may be suboptimal programming of the device, which has particular considerations as compared to standard pacemakers. Hemodynamic response to pacing may be affected by timing of the atrioventricular (AV) interval, affecting synchronicity of atrial and ventricular contraction. In addition current biventricular devices have separate right and left ventricular channels that allow programming of an interventricular (VV) interval with right or left ventricular preexcitation. This article focuses on the parameters that may be optimized for biventricular pacing, and reviews the different techniques currently available for this application, with special emphasis paid to echocardiography.

Algorithms↗
PubMed2006

Narrow, slow-conducting isthmus dependent left atrial reentry developing after ablation for atrial fibrillation: ECG characterization and elimination by focal RF ablation.

INTRODUCTION: The complete circuit of reentrant left atrial tachycardias (LATs) occurring after ablation for atrial fibrillation (AF) has not been well described. Identifying discrete isthmuses critical to these LATs may simplify their elimination by catheter ablation. METHODS AND RESULTS: Fifteen patients (all male, 56 +/- 8 years) with 15 reentrant LATs following AF ablation underwent activation and entrainment mapping. Eleven patients (11 LATs) had a single localized site with low amplitude (0.16 +/- 0.05 mV), fractionated long duration (131 +/- 23 msec) electrograms coinciding with an isoelectric interval of 106 +/- 24 msec between flutter waves on all 12 ECG leads. Three-dimensional mapping and entrainment revealed this site to be a narrow markedly slowly conducting isthmus adjacent to ablated left (n = 8) or right (n = 3) pulmonary vein (PV) ostia, and critical to nine small diameter (15 +/- 3 mm) and two large diameter (49 +/- 2 mm) circuits. One radiofrequency (RF) application on this isthmus eliminated LAT in all 11 patients. Four patients (four LATs) with large circuits around the mitral annulus and/or PV ostia lacked isoelectric ECG intervals and slow-conducting isthmuses and required multiple RF applications across anatomically wide, rapidly conducting isthmuses. CONCLUSION: Focally ablatable narrow isthmuses of slow conduction are critical for the majority of reentrant LAT occurring after ablation for AF. The role and presence of these isthmuses can be anticipated by observing significant isoelectric intervals between flutter waves on all 12-surface ECG leads. Their distinctive electrophysiological characteristics allow their identification and elimination by simple RF ablation.

Atrial Fibrillation↗
PubMed2006

Percutaneous ablation of atrial fibrillation: for whom and how?

Recent developments in our understanding of atrial fibrillation (AF) have focused on the key role of pulmonary vein initiators of multiple wavelet reentry in the atria. Percutaneous catheter ablation of atrial fibrillation is commonly performed by electrical disconnection of pulmonary vein myocardium from the left atrium. As a result, pulmonary vein foci can no longer drive the atria into fibrillation. At present, the procedure is offered to patients with paroxysmal atrial fibrillation refractory to multiple antiarrhythmic agents. For patients with persistent atrial fibrillation, supplementary linear lesions in the left atrium may be necessary. Success rates (AF elimination) are 90% without drugs in case of paroxysmal atrial fibrillation and 80% for persistent atrial fibrillation. Complications including pulmonary vein stenosis are uncommon.

Atrial Fibrillation↗
PubMed2005

Acute pyloric spasm and gastric hypomotility: an extracardiac adverse effect of percutaneous radiofrequency ablation for atrial fibrillation.

OBJECTIVES: This study sought to describe a new adverse effect of percutaneous radiofrequency (RF) ablation for atrial fibrillation (AF). BACKGROUND: Extension of the RF lesion beyond atrial myocardium may affect mediastinal structures other than the esophagus. METHODS: Circular mapping-guided isolation of the pulmonary veins was performed in two different electrophysiology laboratories, either individually and supplemented by ostial and posterior left atrial (LA) ablation or two by two with a series of ostial and posterior LA lesions. The RF energy was delivered point by point through a 5-mm open-tip irrigated catheter (40 W maximum) or an 8-mm-tip catheter (45 W maximum). RESULTS: In four (two in each electrophysiology laboratory) of 367 patients undergoing catheter ablation for AF, abdominal pain and distension developed within 48 h after the procedure. Investigation showed acute pyloric spasm and gastric hypomotility, probably the result of LA endocardially delivered RF affecting the periesophageal vagi. Complete spontaneous recovery occurred in two patients, but laparoscopic esophagojejunal anastomosis and endoscopic intra-pyloric Botulinum toxin injection, respectively, were performed to remedy delayed gastric emptying in two patients. CONCLUSIONS: Thermal injury during endocardial LA RF energy delivery may extend into the mediastinum and rarely may involve the periesophageal nerves, resulting in a syndrome of acute delayed gastric emptying. Marked anatomic variability of periesophageal vagi renders it difficult to reliably avoid the area overlying this plexus, therefore, we advocate a reduction in maximum RF power and application duration on all of the posterior LA to try to avoid this complication.

Abdominal Pain↗
PubMed2005

Wavelet transform for analysis of heart rate variability preceding ventricular arrhythmias in patients with ischemic heart disease.

INTRODUCTION: Studies evaluating changes in HRV preceding the onset of ventricular arrhythmias using conventional techniques have shown inconsistent results. Time-frequency analysis of HRV is traditionally performed using short-term Fourier transform (STFT). Wavelet transform (WT) may however be better suited for analyzing non-stationary signals such as heart rate recordings. METHODS AND RESULTS: We studied patients with a history of myocardial infarction implanted with a defibrillator with an extended memory. The RR intervals during the 51 min preceding ventricular events requiring electrical therapy were retrieved, and HRV studied by WT and STFT. 111 episodes of ventricular arrhythmia were retrieved from 41 patients (38 males, age 64 +/- 8 years). Heart rate increased significantly before arrhythmia. There was no significant variation in low frequency / high frequency components (LF/HF) observed for the group as a whole, probably due to a great degree of heterogeneity amongst individuals. A subset of 30 patients also had heart rate recordings performed during normal ICD follow-up. WT did not show any difference in HRV before arrhythmia onset and during control conditions. CONCLUSION: Variations in HRV before onset of ventricular arrhythmias were not apparent in this large dataset, despite use of optimal tools for studying time-frequency analysis.

Aged↗
PubMed2005

Quantitative study of nerves of the human left atrium.

OBJECTIVES: To quantify and study the distribution of innervation of the left atrium and the pulmonary veins in humans. BACKGROUND: Damage to cardiac nerves has been hypothesized as the explanation for successful radiofrequency ablation of atrial fibrillation. METHODS: From January 2003 to September 2003, histologic and quantitative studies of innervation of the left atrium and the pulmonary veins was performed in 43 consecutive necropsied adult hearts (30 men and 3 women; mean age 45.5 +/- 12.4 years). The left atrium was sectioned in 1-cm slices from left to right, with the plane of section perpendicular to the long axis of the heart. Sections of the pulmonary veins at their ostia and sections 1 cm away of this structure also were obtained. Nerve fiber density was counted manually for each case and expressed as the mean number per slice. RESULTS: Numerous epicardial nerve fibers and ganglia having distinct patterns of distribution in the left atrium were found. Nerve density was significantly higher at the ostia of the four pulmonary veins than in their distal part (7.1 +/- 2.1 vs 5.2 +/- 1.3 for left upper pulmonary vein; 6.3 +/- 1.5 vs 5.2 +/- 1.7 for right upper pulmonary vein; 7.4 +/- 2 vs 5.9 +/- 2 for left lower pulmonary vein; 6.7 +/- 1.8 vs 3.9 +/- 1.3 for right lower pulmonary vein). The left superior vein was significantly more innervated than the right inferior vein (12.3 +/- 3 vs 10.6 +/- 1.4). Gradients of innervation were found from right to left (9.8 +/- 4.6 vs 18.5 +/- 6.6, P < .05) and from the front to the rear of the atrium (17.2 +/- 6.4 vs 20.7 +/- 6.5, P < .05). The same heterogeneous distribution was observed at the myocardial level but with thinner nerve fibers, making quantification difficult. Only very thin nerve fibers were present in the endocardium. CONCLUSIONS: The human left atrium exhibits several gradients of innervation at discrete sites. These findings may have clinical implications for radiofrequency ablation of atrial fibrillation.

Adolescent↗