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Henri Sunthorn

Publications and source records attributed to Henri Sunthorn.

13 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

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

Reducing unnecessary right ventricular pacing with the managed ventricular pacing mode in patients with sinus node disease and AV block.

BACKGROUND: Frequent and unnecessary right ventricular apical pacing increases the risk of atrial fibrillation or congestive heart failure. We evaluated a new pacing algorithm, managed ventricular pacing (MVP) which automatically changes modes between AAI/R and DDD/R in patients receiving pacemakers for symptomatic bradycardia. METHODS: Patients were randomized to the MVP mode or DDD/R mode for 1 month and then crossed over to the alternate pacing modality for an additional month. On completion of the crossover phase, the pacing mode selected was individualized and patients were followed for an additional 4 months. RESULTS: Of the 129 patients who successfully completed the crossover study, the cumulative percent ventricular pacing was significantly reduced in the MVP mode (median 1.4%) compared to the DDD/R mode (median 89.6%, 94.0% relative reduction; 95% CI 89.3-98.8%, P < 0.001). Patients with sinus node disease (SND, n = 51) when compared to patients with AV block (AVB) (n = 68) experienced a greater reduction in ventricular pacing with the MVP mode compared to the DDD/R mode (median relative reduction 99.1%; 95% CI 97.5-99.9% vs median relative reduction 60.1%; 95% CI 16.7-93.9% P < 0.001). The reduced percent ventricular pacing during MVP was sustained over longer term follow-up. CONCLUSIONS: The majority of patients with a bradycardia indication for cardiac pacing do not require ventricular pacing most of the time. The MVP mode significantly reduces unnecessary right ventricular pacing. This mode benefits even patients with intermittent AVB and is sustained over longer term follow-up.

Aged↗
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

[Management of end-stage heart failure].

Non-medical approaches to end-stage heart failure (ESHF) include heart transplantation, but also implantable cardioverter-defibrillators, cardiac resynchronization therapy and ventricular assist devices. These techniques might be used as a bridge to transplant, as a bridge to recovery or as destination therapy. Optimal medical therapy of ESHF should include an angiotensin-converting enzyme inhibitor, a beta-blocker and spironolactone. Risk stratification in ESHF allows to determine the individual prognosis of each patient with parameters such as echocardiographic criteria, peak exercise oxygen consumption, or plasma BNP levels. Heart transplantation is to be considered if the individual prognosis obtained after stratification is worse than the expected survival of transplant recipients.

Heart Failure↗
PubMed2005

Optimizing sequential biventricular pacing using radionuclide ventriculography.

BACKGROUND: Biventricular pacemakers are usually programmed with the default setting of synchronous biventricular pacing, although the ventricles may be paced sequentially. Whether this parameter is important for optimizing resynchronization therapy is not clear. OBJECTIVES: The purpose of this study was to investigate whether sequential pacing acutely improves left ventricular ejection fraction (LVEF) and dyssynchrony and to assess the feasibility of nuclear ventriculography for device optimization. METHODS: Twenty-seven patients implanted with a biventricular pacemaker or implantable cardioverter-defibrillator for heart failure were studied. LVEF was measured using planar radionuclide ventriculography during simultaneous biventricular pacing and during sequential pacing at four different interventricular intervals ranging from LV-40 (preexciting the left ventricle by 40 ms) to LV+40 (preexciting the right ventricle). Interventricular and intraventricular dyssynchrony were analyzed by phase analysis at each setting. RESULTS: There was great heterogeneity in individual response to VV interval programming. Twenty-four of 27 patients (89%) had significant changes (both favorable and unfavorable) in LVEF at different interventricular delays, with variations of up to 10% in absolute terms. Simultaneous biventricular pacing yielded maximal LVEF in 9 of 27 patients (33%), with a relative increase in LVEF of 18 +/- 14% by optimized sequential pacing in the remaining patients. Interventricular dyssynchrony varied significantly, with least dyssynchrony at the LV-20 setting (P = .024). There were no significant differences in intraventricular dyssynchrony at the different settings. CONCLUSION: Programming VV intervals has considerable impact on LVEF. However, there is a great degree of variation between patients in response to these settings, requiring individual assessment for device optimization.

Aged↗
PubMed2005

Prospective study of axillary vein puncture with or without contrast venography for pacemaker and defibrillator lead implantation.

Axillary vein puncture may be used to implant pacemaker (PM) or cardioverter defibrillator leads, though usually requires venography. We prospectively compared punctures guided by venography versus a new radiological landmark. In 232 patients, the puncture was guided by injecting diluted contrast material via an ipsilateral peripheral vein (group A, n = 142), or without venography using the intersection of the lateral borders of the second and third rib as a radiological landmark, followed by contrast injection in case of failure (group B, n = 90). We implantated 1-3 leads per patient. In group A, implantation was successful in 135 patients (95%) and in group B in 55 patients (61%, P < 0.001 vs group A). Subsequent contrast injection allowed successful implantations in 34 of 35 patients, with an success rate of 97% for the overall study population of 224 patients. Venous access was achieved after a mean of 10.4 +/- 3.2 minutes of skin incision in group A versus 9.4 +/- 3.0 minutes in group B (ns). Pneumothorax occurred in two patients (1% overall). Thus non-contrast guided puncture using a new radiological landmark was successful in a majority of patients. This technique may be useful in absence of ipsilateral peripheral vein access, or presence of contrast allergy.

Aged↗