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Prashanthan Sanders

Publications and source records attributed to Prashanthan Sanders.

At least 73 records · Page 4Linked to original sources
PubMed2004

Electrophysiologic and clinical consequences of linear catheter ablation to transect the anterior left atrium in patients with atrial fibrillation.

OBJECTIVES: To evaluate the feasibility and outcome of ablation to transect the anterior left atrium (LA) in patients with atrial fibrillation (AF). BACKGROUND: While the Maze procedure is effective in maintaining sinus rhythm in patients with AF, it is associated with significant morbidity. This prospective clinical study evaluates the feasibility and consequences of limited LA linear ablation to transect the anterior LA in patients with AF. METHODS: Twenty-four patients (51.2 +/- 7.3 years) with paroxysmal (n = 16) or chronic (n = 8) AF resistant to pulmonary vein (PV) isolation were studied. To transect the anterior LA, linear ablation was performed joining the superior PVs; this line was then connected to the anterior mitral annulus. Pulmonary vein isolation and cavotricuspid isthmus ablation were performed in all cases. Ablation was performed using an irrigated catheter with the endpoint of achieving complete linear block demonstrated by online double potentials, differential pacing techniques, and an activation detour. RESULTS: Of 20 patients in AF prior to linear ablation, arrhythmia terminated in 12 (60%), including half the patients with chronic AF, during ablation. Despite repeated ablation, complete linear block was achieved in only 14 of 24 patients (58%). Complete linear conduction block resulted in an activation detour around the mitral annulus and PVs with a delay of 158 +/- 30 ms (P = .0001), significantly delayed activation of the lateral LA with prolongation of P-wave duration (P = .002), and characteristic change in P-wave morphology during sinus rhythm (P = .002). Of the 14 with anterior LA transection, 4 (29%) have had regular atrial tachycardias due to macroreentry through recovered gaps. Nine of these 14 (64%) have remained arrhythmia-free without antiarrhythmics compared to 3 of 10 (30%) with incomplete block at 28 +/- 4 months following their last procedure (P = .2). CONCLUSIONS: This study demonstrates the feasibility of catheter ablation to transect the anterior LA in humans. While being effective in the termination of AF, this configuration of linear lesions is technically challenging to complete, results in significant delayed LA activation, and is associated with modest long-term arrhythmia suppression.

Atrial Fibrillation↗
PubMed2004

Biventricular pacing and left ventricular pacing in heart failure: similar hemodynamic improvement despite marked electromechanical differences.

INTRODUCTION: We conducted an acute echocardiographic study comparing hemodynamic and ventricular dyssynchrony parameters during left ventricular pacing (LVP) and biventricular pacing (BVP). We sought to clarify the mechanisms responsible for similar hemodynamic improvement despite differences in electrical activation. METHODS AND RESULTS: Thirty-three patients underwent echocardiography prior to implantation with a multisite pacing device (spontaneous rhythm [SR]) and 2 days after implantation (BVP and LVP). Interventricular dyssynchrony (pulsed-wave Doppler), extent of myocardium displaying delayed longitudinal contraction (%DLC; tissue tracking), and index of LV dyssynchrony (pulsed-wave tissue Doppler imaging) were assessed. Compared to SR, BVP and LVP caused similar significant improvement of cardiac output (LVP: 3.2 +/- 0.5, BVP: 3.1 +/- 0.7, SR: 2.3 +/- 0.6 L/min; P < 0.01) and mitral regurgitation (LVP: 25.1 +/- 10, BVP: 24.7 +/- 11, baseline: 37.9 +/- 14% jet area/left atria area; P < 0.01). LVP resulted in a smaller index of LV dyssynchrony than BVP (29 +/- 10 vs 34 +/- 14; P < 0.05). However, LVP exhibited a longer aortic preejection delay (220 +/- 34 vs 186 +/- 28 msec; P < 0.01), longer LV electromechanical delays (244.5 +/- 39 vs 209.5 +/- 47 msec; P < 0.05), greater interventricular dyssynchrony (56.6 +/- 18 vs 31.4 +/- 18; P < 0.01), and higher%DLC (40.1 +/- 08 vs 30.3 +/- 09; P < 0.05), leading to shorter LV filling time (387 +/- 54 vs 348 +/- 44 msec; P < 0.05) compared to BVP. CONCLUSION: Although LVP and BVP provide similar hemodynamic improvement, LVP results in more homogeneous but substantially delayed LV contraction, leading to shortened filling time and less reduction in postsystolic contraction. These data may influence the choice of individual optimal pacing configuration.

Aged↗
PubMed2004

Fever as a precipitant of idiopathic ventricular fibrillation in patients with normal hearts.

INTRODUCTION: Ventricular fibrillation (VF) is the main mechanism of sudden cardiac death. The clinical precipitants of sudden cardiac death due to idiopathic VF are poorly characterized. Emerging evidence implicates triggers originating predominantly from the distal Purkinje arborization and the right ventricular outflow tract. METHODS AND RESULTS: We report three patients without structural heart disease or repolarization abnormalities in whom a febrile illness was the only concurrent disease associated with unexpected sudden cardiac death due to VF storm. An automated defibrillator was implanted in all three patients. In one patient with persistent recurrent VF episodes, mapping demonstrated the origin of these triggers was from the Purkinje arborization of the anterior wall of the right ventricle. Ablation at a site of earliest activation during ectopy, where pace mapping was concordant and Purkinje potential preceded the onset of ventriculogram, resulted in suppression of all arrhythmias. After follow-up of 22, 9, and 18 months in the three patients, no ventricular arrhythmias have been recorded. CONCLUSION: We present a series of patients in whom an apparently benign febrile illness was associated with malignant ventricular arrhythmias in the absence of cardiac disease or other factors known to precipitate sudden cardiac death. Physicians should be aware of this possible phenomenon in cases of febrile illness associated with syncope.

Aged↗
PubMed2003

Reversal of atrial mechanical dysfunction after cardioversion of atrial fibrillation: implications for the mechanisms of tachycardia-mediated atrial cardiomyopathy.

BACKGROUND: Atrial mechanical "stunning" develops after cardioversion of atrial fibrillation (AF) and is implicated in the genesis of thromboembolic complications. However, the mechanisms responsible for this phenomenon are poorly understood. Whether atrial mechanical dysfunction caused by AF can be reversed by pacing at increased rates or by pharmacological agents is unknown. METHODS AND RESULTS: Twenty-six patients with AF undergoing cardioversion were dichotomized prospectively on the basis of the duration of arrhythmia as short-duration (1 to 6 months) or long-duration (> or =3 years) AF. Left atrial appendage emptying velocities (LAAEVs) and spontaneous echocardiographic contrast (LASEC) were assessed by transesophageal echocardiography during AF, after reversion to sinus rhythm, during atrial pacing at cycle lengths of 750 to 250 ms, after a postpacing pause, and with isoproterenol. In patients with short-duration AF, LAAEV decreased (42.0+/-2.7 to 18.5+/-2.0 cm/s; P<0.0001) and LASEC increased (0.9+/-0.3 to 2.2+/-0.3; P<0.01) with termination of AF; pacing increased LAAEV (48.3+/-4.1 cm/s; P<0.0001) and decreased LASEC (1.5+/-0.3; P<0.01); isoproterenol increased LAAEV (73.3+/-7.8 cm/s; P<0.0001) and decreased LASEC (0.3+/-0.2; P<0.01); and the postpacing pause increased LAAEV (68.3+/-3.8 cm/s; P<0.0001). In contrast, patients with long-duration AF demonstrated a significantly attenuated response of atrial mechanical function at each time point. With termination of AF, LAAEV decreased (19.1+/-2.6 to 8.2+/-1.0 cm/s; P=0.003) and LASEC increased (2.0+/-0.2 to 3.3+/-0.2; P<0.01); pacing increased LAAEV (18.4+/-2.7 cm/s; P<0.0001) and decreased LASEC (2.3+/-0.2; P<0.01); isoproterenol increased LAAEV (26.1+/-3.9 cm/s; P=NS to equivalent atrial rate) and decreased LASEC (1.0+/-0.3; P<0.01); and the postpacing pause increased LAAEV (27.2+/-2.4 cm/s; P=0.007). CONCLUSIONS: Atrial pacing at increased rates and isoproterenol can reverse atrial mechanical stunning associated with short-duration AF. In contrast, long-duration AF is associated with an attenuated response to these maneuvers. These findings suggest a functional contractile apparatus in the mechanically remodeled atrium caused by AF; however, with longer durations of AF, additional factors may determine atrial mechanical function.

Adrenergic beta-Agonists↗
PubMed2003

Electrophysiological and electrocardiographic characteristics of focal atrial tachycardia originating from the pulmonary veins: acute and long-term outcomes of radiofrequency ablation.

BACKGROUND: The objective of this study was to describe the electrophysiological characteristics, anatomic distribution, and long-term outcome after focal ablation (RFA) of pulmonary vein (PV) atrial tachycardia (AT). Both atrial fibrillation (AF) and AT may be due to a rapidly firing focus in the PVs. Whether these represent two aspects of the same process is unknown. METHODS AND RESULTS: Twenty-seven patients with 28 PV(16%) ATs of a consecutive series of 172 undergoing RFA for focal AT are reported. The mean age was 39+/-16 years, with symptoms for 9+/-14 years resistant to 1.7+/-0.8 medications. AT occurred spontaneously or with isoproterenol in all patients and was not inducible with PES in any. The distribution of PV ATs was right superior PV, 11; left superior PV, 11; left inferior PV, 5; and right inferior PV, 1; 26of 28 foci (93%) were ostial. RFA was successful in 28 of 28 PV ATs acutely. RFA was focal in 25 of 28, with PV isolation of a single target vein in 3. There were 4 recurrences at a mean of 3.3 months. Repeat RFA was performed in all 4 and successful in 3 of 4. All but one recurrence occurred from the same site. Long-term success was achieved in 26 of 27 (96%) patients at mean follow-up of 25+/-22 months. No patients have had subsequent development of AF or AT from a different site. CONCLUSIONS: PV AT has a distribution similar to PV AF, with a propensity to upper veins. However, the majority of foci are ostial, and only a small percentage occur from deep in the PV. Focal RFA is associated with high long-term success, with freedom from both AT from other sites and from AF. PV AT is a localized process and therefore may be different from PV AF.

Adolescent↗
PubMed2003

Reverse remodeling of sinus node function after catheter ablation of atrial fibrillation in patients with prolonged sinus pauses.

BACKGROUND: Symptomatic prolonged sinus pauses on termination of atrial fibrillation (AF) are an indication for pacemaker implantation. We evaluated sinus node function and clinical outcome in patients with prolonged sinus pauses on termination of arrhythmia who underwent ablation of paroxysmal AF. METHODS AND RESULTS: Twenty patients with paroxysmal AF and prolonged sinus pauses (> or =3 seconds) on termination of AF underwent ablation between May 1995 and November 2002. Patients with sinus pauses independent of episodes of AF were excluded from the analysis. The procedure included pulmonary vein and linear atrial ablation. After ablation, sinus node function was assessed during the first week and at 1, 3, and 6 months, by 24-hour ambulatory monitoring to determine the mean heart rate and heart rate range, and by exercise testing to determine the maximal heart rate. Corrected sinus node recovery time was determined at the completion of ablation and at 24.0+/-11.3 months at 600 and 400 ms. After AF ablation, there was a significant improvement of sinus node function, with an increase in the mean heart rate (P=0.001), maximal heart rate (P<0.0001), and heart rate range (P<0.0001). The corrected sinus node recovery time decreased in all patients evaluated at 600 ms (P=0.016) and 400 ms (P=0.019). At 26.0+/-17.6 months, 18 patients (85%) had no recurrence of AF (in the absence of medication), with no symptoms attributable to bradycardia or sinus pauses on ambulatory monitoring. Two patients had infrequent episodes of AF, 1 requiring pacemaker implantation. CONCLUSIONS: Prolonged sinus pauses after paroxysms of AF may result from depression of sinus node function that can be eliminated by curative ablation of AF. This is accompanied by improvement in parameters of sinus node function, suggesting reverse remodeling of the sinus node.

Atrial Fibrillation↗
PubMed2003

Electrical remodeling of the atria in congestive heart failure: electrophysiological and electroanatomic mapping in humans.

BACKGROUND: Atrial fibrillation (AF) frequently complicates congestive heart failure (CHF). However, the electrophysiological substrate for AF in humans with CHF remains unknown. We evaluated the electrophysiological and electroanatomic characteristics of the atria in patients with CHF. METHODS AND RESULTS: Twenty-one patients (aged 53.7+/-13.6 years) with symptomatic CHF (left ventricular ejection fraction 25.5+/-6.0%) and 21 age-matched controls were studied. The following were evaluated: effective refractory periods (ERPs) from the high and low lateral right atrium (LRA), high septal right atrium, and distal coronary sinus (CS); conduction time along the CS and LRA; corrected sinus node recovery times; P-wave duration; and conduction at the crista terminalis. In a subset, electroanatomic mapping was performed to determine atrial activation, regional conduction velocity, double potentials, fractionated electrograms, regional voltage, and areas of electrical silence. Patients with CHF demonstrated an increase in atrial ERP with no change in the heterogeneity of refractoriness, an increase of atrial conduction time along the LRA and the CS, prolongation of the P-wave duration and corrected sinus node recovery times, and greater number and duration of double potentials along the crista terminalis. Electroanatomic mapping demonstrated regional conduction slowing with a greater number of electrograms with fractionation or double potentials, associated with areas of low voltage and electrical silence (scar). Patients with CHF demonstrated an increased propensity for AF with single extrastimuli, and induced AF was more often sustained. CONCLUSIONS: Atrial remodeling due to CHF is characterized by structural changes, abnormalities of conduction, sinus node dysfunction, and increased refractoriness. These abnormalities may be responsible in part for the increased propensity for AF in CHF.

Atrial Function↗
PubMed2003

Mapping and ablation of ventricular fibrillation associated with long-QT and Brugada syndromes.

BACKGROUND: The long-QT and Brugada syndromes are important substrates of malignant ventricular arrhythmia. The feasibility of mapping and ablation of ventricular arrhythmias in these conditions has not been reported. METHODS AND RESULTS: Seven patients (4 men; age, 38+/-7 years; 4 with long-QT and 3 with Brugada syndrome) with episodes of ventricular fibrillation or polymorphic ventricular tachycardia and frequent isolated or repetitive premature beats were studied. These premature beats were observed to trigger ventricular arrhythmias and were localized by mapping the earliest endocardial activity. In 4 patients, premature beats originated from the peripheral right (1 Brugada) or left (3 long-QT) Purkinje conducting system and were associated with variable Purkinje-to-muscle conduction times (30 to 110 ms). In the remaining 3 patients, premature beats originated from the right ventricular outflow tract, being 25 to 40 ms ahead of the QRS. The accuracy of mapping was confirmed by acute elimination of premature beats after 12+/-6 minutes of radiofrequency applications. During a follow-up of 17+/-17 months using ambulatory monitoring and defibrillator memory interrogation, no patients had recurrence of symptomatic ventricular arrhythmia but 1 had persistent premature beats. CONCLUSIONS: Triggers from the Purkinje arborization or the right ventricular outflow tract have a crucial role in initiating ventricular fibrillation associated with the long-QT and Brugada syndromes. These can be eliminated by focal radiofrequency ablation.

Adult↗
PubMed2003

Focal atrial tachycardia arising from the mitral annulus: electrocardiographic and electrophysiologic characterization.

OBJECTIVES: The study was done to characterize the electrocardiographic and electrophysiologic features of focal atrial tachycardia originating at the mitral annulus (MA). BACKGROUND: Though the majority of left atrial tachycardias originate around the ostia of the pulmonary veins, only isolated reports have described focal tachycardia originating from the MA. METHODS: Seven patients of a consecutive series of 172 patients undergoing radiofrequency ablation for focal atrial tachycardia are reported. Electrophysiologic study involved catheters positioned along the coronary sinus (CS), crista terminalis (CT), His bundle, and a mapping/ablation catheter. RESULTS: All seven patients had tachycardia foci originating from the superior region of the MA in close proximity to the left fibrous trigone and mitral-aortic continuity. These foci demonstrated a characteristic P-wave morphology and endocardial activation pattern. The P-wave morphology in the precordial leads typically showed a biphasic pattern, with an inverted component followed by an upright component. The P-wave was consistently of low amplitude in the limb leads. Earliest endocardial activity occurred at the His bundle region in all seven patients. In general, CS activation was proximal to distal, and mid-CT activation was earlier than high or low CT. Ablation was successful at the superior aspect of the MA in all patients. CONCLUSIONS: The MA is an unusual but important site of origin for focal atrial tachycardia, with a propensity to be localized to the superior aspect. It can be suspected as a potential anatomic site of tachycardia origin from analysis of P-wave morphology and the atrial endocardial activation sequence map. Using mapping targeted to anatomic structures achieved a high success rate for ablation.

Adult↗
PubMed2003

Effect of chronic right atrial stretch on atrial electrical remodeling in patients with an atrial septal defect.

BACKGROUND: Adults with an atrial septal defect (ASD) frequently develop late atrial arrhythmias. We sought to characterize the pattern and persistence of atrial electrical remodeling caused by chronic right atrial (RA) stretch in this group. METHODS AND RESULTS: Thirteen ASD patients without atrial arrhythmia (42+/-10 years old; RA volume, 65+/-16 mL) and 17 normal control subjects (44+/-11 years old; RA volume, 38+/-8 mL) had electrophysiological study to measure (1) atrial effective refractory period (AERP) from the low lateral/high lateral/high septal RA and distal coronary sinus (CS), (2) dispersion of AERP, (3) lateral-RA and CS conduction time during constant pacing, (4) conduction delay across the crista terminalis measuring the number of crista catheter bipoles (0-10) recording discrete double potentials during pacing, (5) corrected sinus node recovery time, and (6) P-wave duration. After ASD closure (8.3+/-5.6 months), follow-up echo studies (n=12) and electrophysiological study (n=4) were performed. The low-lateral AERP, P-wave duration, sinus node recovery time, and extent of conduction delay across the crista terminalis were significantly greater in ASD patients. No differences were found for other measured electrophysiological study parameters. At follow-up, there was incomplete resolution of RA volume (47+/-12 mL; P<0.01 versus before surgery), a trend toward shortening of the AERP at the lateral RA and an increase at the distal CS and high septal RA, but persisting extensive, widely split crista double potentials. CONCLUSIONS: Chronic RA stretch because of ASD causes electrical remodeling with modest increases in RA ERP, conduction delay at the crista terminalis, and sinus node dysfunction. Conduction delay at the crista terminalis persists beyond ASD closure and may contribute to the long-term atrial arrhythmia substrate in this condition.

Adult↗
PubMed2003

Catheter Ablation of Ventricular Fibrillation in Structurally Normal Hearts Targeting the RVOT and Purkinje Ectopy.

Catheter ablation for ventricular fibrillation in structurally normal hearts is in its infancy. Recently, catheter ablation of idiopathic ventricular fibrillation as well as ventricular fibrillation associated with the long QT and Brugada syndromes has been described. This review article is a summary of our current understanding of the technique and results of catheter ablation of ventricular fibrillation in structurally normal hearts.

Adolescent↗