The role of nonpharmacologic therapies for the treatment of atrial fibrillation.
Explore the source record for details and available documents.
Atrial Fibrillation↗
Biomedical subjects
M D Lesh
Publications and source records attributed to M D Lesh.
Autonomic nervous system tone measured by baroreflex sensitivity is depressed in patients with end-stage liver disease.
OBJECTIVES: Chronic liver disease is often associated with impairment of autonomic nervous system (ANS) reflexes. Baroreflex sensitivity (BRS) testing is an inexpensive, relatively noninvasive test that can be used to assess ANS tone. The aims of the present study were to determine the prevalence of ANS dysfunction in cirrhotics who are being considered for liver transplantation and to explore the potential use of BRS as a prognostic tool in identifying patients awaiting transplantation who are at increased risk for death. METHODS: We studied nine cirrhotics who were awaiting liver transplantation and seven controls without liver disease. BRS (ms/mm Hg) was measured using the phenylephrine method. RESULTS: BRS (mean +/- SEM) (ms/mm Hg) was significantly lower in cirrhotics compared with controls (4.2 +/- 0.9 vs 21.1 +/- 3.8 ms/mm Hg; p < 0.05). Furthermore, BRS was lower in cirrhotics with hepatic encephalopathy compared with those without (2.6 +/- 0.9 vs 6.1 +/- 1.0 ms/mm Hg; p < 0.05) and there was a trend toward lower BRS values in Child-Pugh class C patients as compared with class B (3.8 +/- 1.3 vs 5.3 +/- 1.2 ms/mm Hg; p = 0.3). At follow-up (9 months), one patient had died and one underwent liver transplantation. These two patients also had the most severely impaired vagal tone (BRS = 0 and 1.2 ms/mm Hg, respectively). CONCLUSIONS: Vagal tone, as assessed by BRS, is markedly depressed in cirrhotic patients awaiting liver transplantation.
Adult↗
Body surface mapping during pacing at multiple sites in the human atrium: P-wave morphology of ectopic right atrial activation.
BACKGROUND: The morphology and polarity of the P wave on 12-lead ECG are of limited clinical value in localizing ectopic atrial rhythms. It was the aim of this study to assess the spatial resolution of body surface P-wave integral mapping in identifying the site of origin of ectopic right atrial (RA) impulse formation in patients without structural atrial disease. METHODS AND RESULTS: Sixty-two-lead ECG recordings were obtained during RA pacing at 86 distinct endocardial sites in nine patients with normal biatrial anatomy. After P-wave integral maps were generated for each paced activation sequence, 17 groups with nearly identical map features were visually selected, and a mean P-wave integral map was computed for each group. Supportive statistical analysis to corroborate qualitative group selection was performed by assessment of (1) intragroup pattern uniformity by use of jackknife correlation coefficient analysis of the integral maps contained in each group and (2) intergroup pattern variability by use of the calculation of cross correlations between the 17 mean integral maps. The spatial resolution of paced P-wave body surface mapping in the right atrium was obtained by estimating the area size of endocardial segments with nearly identical P-wave integral maps by use of a biplane fluoroscopic method to compute the three-dimensional position of each pacing site. The latter approach yielded a mean endocardial segment size of 3.5+/-2.9 cm2 (range, 0.79 to 10.75 cm2). CONCLUSIONS: Use of the P-wave morphology on the 62-lead surface ECG in patients with normal biatrial anatomy allows separation of the origin of ectopic RA impulse formation into one of 17 different endocardial segments with an approximated area size of 3.5 cm2. This database of paced P-wave integral maps provides a versatile clinical tool to perform detailed noninvasive localization of right-sided atrial tachycardia before radiofrequency catheter ablation.
Adult↗
Anatomic and electrophysiologic relation between the coronary sinus and mitral annulus: implications for ablation of left-sided accessory pathways.
To determine whether precise left-sided accessory pathway localization is possible from the coronary sinus, electrocardiogram (ECG) characteristics from the coronary sinus pair demonstrating earliest activation via the accessory pathway were compared to simultaneous mitral annular ablation catheter ECGs at successful ablation sites in 48 patients. To define the coronary sinus-mitral annular relation, the coronary sinus to mitral annulus distance (D) was measured at sequential distances from the coronary sinus os in 10 cadaver hearts. Mitral annular ECGs demonstrated earliest activation via the accessory pathway more frequently than the earliest coronary sinus pair (p < 0.001), more frequent continuous electrical activity (p < 0.001), and more frequent accessory pathway potentials (p < 0.01). D was >10 mm at 20, 40, and 60 mm, respectively, from the coronary sinus os. Coronary sinus ECGs do not precisely localize left-sided accessory pathways, which may be due in part to an average anatomic separation of more than 10 mm between the coronary sinus and accessory pathways bridging the mitral annulus.
Adult↗
Progress toward a catheter ablative cure of atrial fibrillation.
Explore the source record for details and available documents.
Adult↗
Body surface mapping of atrial arrhythmias: atlas of paced P wave integral maps to localize the focal origin of right atrial tachycardia.
Successful curative treatment of right atrial tachycardia (AT) can be obtained provided detailed catheter activation mapping of the target site for radiofrequency energy application has been accomplished. However, right AT mapping may be difficult with a single roving catheter due to infrequent presence or noninducibility of the arrhythmia. The present report describes the preliminary clinical use of body surface mapping as an adjunctive noninvasive method to identify the region of AT origin prior to catheter ablation. This technique has been previously applied to develop a reference data base of 17 different paced P wave integral map patterns. The data base was designed by performing right atrial pace mapping in patients without structural heart disease. Each P wave integral map pattern in the data base is unique to ectopic activation onset in a circumscribed right atrial endocardial segment. Localization of the segment of AT origin is accomplished by matching the P wave integral map of a single AT beat with the data base of paced P wave integral maps. The use of body surface mapping as an integral part of the mapping protocol during radiofrequency catheter ablation of right AT offers the possibility to: (1) noninvasively determine the arrhythmogenic target area for ablation using a single beat analysis approach; (2) confine detailed catheter activation mapping to a limited area; and (3) accelerate the overall procedure and limit fluoroscopic exposure by reducing the time required for mapping.
Body Surface Potential Mapping↗
"Cristal tachycardias": origin of right atrial tachycardias from the crista terminalis identified by intracardiac echocardiography.
OBJECTIVES: We sought to use intracardiac echocardiography (ICE) to identify the anatomic origin of focal right atrial tachycardias and to define their relation with the crista terminalis (CT). BACKGROUND: Previous studies using ICE during mapping of atrial flutter and inappropriate sinus tachycardia have demonstrated an important relation between endocardial anatomy and electrophysiologic events. Recent studies have suggested that right atrial tachycardias may also have a characteristic anatomic distribution. METHODS: Twenty-three consecutive patients with 27 right atrial tachycardias were included in the study. ICE was used to facilitate activation mapping in relation to endocardial structures. A 20-pole catheter was positioned along the CT under ICE guidance. ICE was also used to assist in guiding detailed mapping with the ablation catheter in the right atrium. RESULTS: Of 27 focal right atrial tachycardias, 18 (67%, 95% confidence interval [CI] 46% to 83%) were on the CT (2 high medial, 8 high lateral, 6 mid and 2 low). ICE identified the location of the tip of the ablation catheter in immediate relation to the CT in all 18 cases. The 20-pole mapping catheter together with echocardiographic visualization of the CT provided a guide to the site of tachycardia origin along this structure. Radiofrequency ablation was successful in 26 (96%) of 27 (95% CI 81% to 100%) right atrial tachycardias. CONCLUSIONS: This study demonstrates that approximately two thirds of focal right atrial tachycardias occurring in the absence of structural heart disease will arise along the CT. Recognition of this common distribution may potentially facilitate mapping and ablation of these tachycardias.
Adolescent↗
Narrow complex tachycardia with VA block: diagnostic and therapeutic implications.
To review our experience with cases of narrow complex tachycardia with VA block, highlighting the difficulties in the differential diagnosis, and the therapeutic implications. Prior reports of patients with narrow complex tachycardia with VA block consist of isolated case reports. The differential diagnosis of this disorder includes: automatic junctional tachycardia, AV nodal reentry with final upper common pathway block, concealed nodofascicular (ventricular) pathway, and intra-Hissian reentry. Between June 1994 and January 1996, six patients with narrow complex tachycardia with episodes of ventriculoatrial block were referred for evaluation. All six patients underwent attempted radiofrequency ablation of the putative arrhythmic site. Three of six patients had evidence suggestive of a nodofascicular tract. Intermittent antegrade conduction over a left-sided nodofascicular tract was present in two patients and the diagnosis of a concealed nodofascicular was made in the third patient after ruling out other tachycardia mechanisms. Two patients had automatic junctional tachycardia, and one patient had atrioventricular nodal reentry with proximal common pathway block. Attempted ablation in the posterior and mid-septum was unsuccessful in patients with nodofascicular tachycardia. In contrast, those with atrioventricular nodal reentry and automatic junctional tachycardia readily responded to ablation. The presence of a nodofascicular tachycardia should be suspected if: (1) intermittent antegrade preexcitation is recorded, (2) the tachycardia can be initiated with a single atrial premature producing two ventricular complexes, and (3) a single ventricular extrastimulus initiates SVT without a retrograde His deflection. The presence of a nodofascicular pathway is common in patients with narrow complex tachycardia and VA block. Unlike AV nodal reentry and automatic junctional tachycardia, the response to ablation is poor.
Adolescent↗
Acute effects of intraoperative multisite ventricular pacing on left ventricular function and activation/contraction sequence in patients with depressed ventricular function.
INTRODUCTION: We hypothesized that simultaneous right and left ventricular apical pacing would result in improvement in left ventricular function due to improved coordination of segmental ventricular contraction. Structural changes in ventricular muscle present in dilated cardiomyopathy compromise ventricular excitation and mechanical contraction. METHODS AND RESULTS: Eleven patients with depressed left ventricular function having cardiac surgery underwent epicardial multisite pacing with continuous transesophageal echocardiographic imaging. Quantitative measurement of percent fractional area change was performed, and segmental changes in contraction sequence resulting from simultaneous right and left ventricular pacing were assessed by application of phase analysis to recorded transesophageal images. There was no statistically significant difference between the paced QRS duration achieved with simultaneous right and left ventricular apical pacing and the native QRS duration (139+/-39 msec vs 106+/-18 msec, P = NS), but all other paced modes resulted in longer QRS durations. Percent fractional area change improved with simultaneous right and left ventricular apical pacing but not with other paced modes (41.5+/-11.9 vs 34.3+/-9.7, P < 0.01). Phase analysis demonstrated a resequencing of segmental left ventricular activation/contraction when compared to baseline ventricular activation. CONCLUSION: Simultaneous right and left ventricular apical pacing results in acute improvements in global ventricular performance in patients with depressed ventricular function. Improvements may result from pacing-induced global coordination through recruitment of left and right ventricular apical and septal segments critical to effective ventricular contraction.
Cardiac Pacing, Artificial↗
Organized activation during atrial fibrillation in man: endocardial and electrocardiographic manifestations.
INTRODUCTION: Atrial fibrillation is not entirely random, but little is known about the spatiotemporal endocardial organization and its surface ECG manifestations. METHODS AND RESULTS: In 16 patients with atrial fibrillation (chronic, n = 14), endocardial mapping of the trabeculated, the posteroseptal smooth right atrium, and the coronary sinus was performed using multipolar catheters. The surface ECG was analyzed by determining "fibrillation wave" (F wave) amplitude, rate, and polarity. During 50 minutes of atrial fibrillation, an organized activation was present 72% +/- 32% of the analyzed time on the trabeculated, 19% +/- 15% on the smooth right atrium (P < 0.01), and 51% +/- 33% along the coronary sinus (P < 0.05). The direction of organized activation was craniocaudal in 72% +/- 16%, caudocranial in 10% +/- 9% (P < 0.01), and indeterminable in 18% +/- 11%. The mean surface F wave amplitude in lead V1 was 0.128 +/- 0.06 mV during 28 seconds of atrial fibrillation with a craniocaudal direction of activation and 0.065 +/- 0.02 mV during a disorganized activation (P < 0.01). A stable relation between surface F waves and organized trabeculated right atrial activation was observed, and the mean F wave cycle length (190 +/- 27 msec) was highly comparable to the simultaneously measured endocardial cycle length (191 +/- 27 msec, correlation coefficient 0.97). F wave polarity in V1 was positive in 12 of 14 patients during craniocaudal and negative in 11 of 14 patients during caudocranial right atrial free-wall activation. CONCLUSION: An organized activation during atrial fibrillation with a predominant craniocaudal direction on the trabeculated right atrium is frequently present and influences the appearance of "coarse" or "fine" atrial fibrillation as well as F wave polarity on the surface ECG.
Adult↗
Use of intracardiac echocardiography during electrophysiologic evaluation and therapy of atrial arrhythmias.
The relationship between endocardial anatomy and the substrate for a variety of atrial arrhythmia mechanisms is being increasingly appreciated. By using intravascular ultrasound imaging systems in the cardiac chambers, direct endocardial visualization can be provided. The advantages include: precise anatomic localization of the ablation catheter tip in relation to important endocardial structures that cannot be visualized with fluoroscopy; the ability to guide ablative procedures partly, or in some instances entirely, by anatomic landmarks; potential reduction in fluoroscopy time; evaluation of stability of catheter tip-tissue contact; confirmation of lesion formation and identification of lesion size and continuity; immediate identification of complications such as clot and pericardial effusion; assistance in the guidance of transseptal puncture; and as a research tool to help in understanding the critical role played by specific endocardial structures in atrial arrhythmogenesis. Presently, intracardiac echocardiography (ICE) is useful as an adjunct in guiding mapping and ablation of focal atrial tachycardia. In our laboratory, it has significant advantage in modification or ablation of sinus node function in patients with inappropriate sinus tachycardia syndrome. Its use in helping to guide ablation of atrial fibrillation remains an exciting, but largely unproved, hypothesis. Better technology will be required if widespread clinical use of ICE is to occur.
Atrial Fibrillation↗
Relationship between atrial fibrillation and typical atrial flutter in humans: activation sequence changes during spontaneous conversion.
BACKGROUND: A transitional rhythm precedes the spontaneous onset of atrial flutter in an animal model, but few data are available in man. METHODS AND RESULTS: In 10 patients, 16 episodes of atrial fibrillation (166+/-236 seconds) converting into atrial flutter during electrophysiological evaluation were analyzed. A 20-pole catheter was used for mapping the right atrial free wall. Preceding the conversion was a characteristic sequence of events: (1) a gradual increase in atrial fibrillation cycle length (150+/-25 ms after onset, 166+/-28 ms before conversion, P<.01); (2) an electrically silent period (267+/-45 ms); (3) "organized atrial fibrillation" (cycle length, 184+/-24 ms) with the same right atrial free wall activation direction as during atrial flutter; (4) another delay on the lateral right atrium (283+/-52 ms); and (5) typical atrial flutter (cycle length, 245+/-38 ms). The coronary sinus generally had a different rate than the right atrial free wall until the beat that initiated flutter, when right atrium and coronary sinus were activated in sequence. During 1313 seconds of fibrillation, there were 171 episodes of "organized atrial fibrillation." An additional activation delay at least 30 ms longer than the mean organized atrial fibrillation cycle length was sensitive (100%) and specific (99%) for impending organization into atrial flutter. During organized atrial fibrillation, right atrial free wall activation was craniocaudal in 70% and caudocranial in 30%, which may explain why counterclockwise flutter is a more common clinical rhythm than clockwise flutter. Atrial flutter never degenerated into fibrillation, even after adenosine infusion. CONCLUSIONS: Anatomic barriers, along with statistical properties of conduction and refractoriness during atrial fibrillation, may explain the remarkably stereotypical pattern of endocardial activation during the initiation of atrial flutter via fibrillation and the rarity of degeneration of flutter to fibrillation once it stabilizes.
Aged↗
Electrophysiological effects of long, linear atrial lesions placed under intracardiac ultrasound guidance.
BACKGROUND: A curative atrial fibrillation procedure will most likely rely on creating transmural linear ablative lesions. However, it is currently unknown whether endocardial radiofrequency lesions can create lines of conduction block. METHODS AND RESULTS: In six pigs, intracardiac echocardiography was used to guide the positioning of multiple coil array catheters to bridge endocardial structures in three right atrial locations: (1) from the crista terminalis to the tricuspid annulus; (2) from the fossa ovalis to the crista terminalis; and (3) from the inferior vena cava to the tricuspid annulus. Once the catheter was positioned, linear lesions were made by radiofrequency energy applied sequentially to each of the four coils. After 15 days, the chest was opened and a 112-electrode epicardial plaque was positioned over the atrial free wall lesion to determine activation patterns. Three lesions were placed in each animal, with a mean procedure time of 47+/-11 minutes. Once adequate contact was determined by intracardiac echocardiography, a single series of radiofrequency application was required to achieve tissue heating (65+/-4 degrees C) with a power of 21+/-10 W. Epicardial mapping demonstrated complete conduction block across the lesions in all animals, with split potentials and disparate activation times (64+/-16 ms) across the lesion. At autopsy, all lesions were discrete, continuous, and without evidence of charring. The lesions were within 0.3+/-0.5 mm of their targeted anatomic locations and measured 21+/-4 mm long and 2.8+/-0.6 mm wide. Histology revealed transmural fibrosis throughout the length of each lesion. CONCLUSIONS: Linear lesions that are electrophysiologically transmural and continuous can be placed in the right atrium of normal pigs. With intracardiac echocardiography, adequate tissue contact over several coil electrodes can be ensured, resulting in short procedure times, efficient energy application, and accurate anatomically linked lesion placement.
Animals↗
P-wave morphology during right atrial pacing before and after atrial flutter ablation--a new marker for success.
Fourteen patients with typical atrial flutter underwent pacing from the low lateral right atrium and the proximal coronary sinus in normal sinus rhythm before and after catheter ablation. During low lateral right atrial pacing, a positive change in P-wave morphology in the inferior leads was noted in every patient (n = 12) in whom bidirectional block was achieved; no recurrence was noted in any of these patients.
Aged↗
Mortality benefit of implantable cardioverter-defibrillator therapy in patients with persistent malignant ventricular arrhythmias despite amiodarone treatment.
Implantable cardioverter defibrillators (ICDs) are very effective in preventing sudden cardiac death. However, debate continues as to whether ICD implantation is superior to amiodarone in prolonging survival in patients with life-threatening ventricular arrhythmias. Of 442 consecutive patients treated with amiodarone, we identified 48 patients with symptomatic ventricular arrhythmias who met all of the following inclusion criteria: (1) had inducible sustained ventricular tachycardia at baseline electrophysiologic study, (2) had an oral amiodarone load of at least 10 g over 10 to 14 days, (3) remained inducible with a hemodynamically unstable ventricular arrhythmia at follow-up electrophysiologic study, and (4) were advised to continue amiodarone therapy and undergo ICD implantation. Patients who agreed to undergo ICD implantation (n = 28) had a lower ejection fraction (29 +/- 9% vs 40 +/- 12% p <0.005) and were younger (61.0 +/- 10 vs 69 +/- 7 years, p <0.01) than patients who refused device implantation (n = 20). Using a Cox proportional-hazards model, defibrillator therapy was the strongest independent predictor of improved survival in patients with an ejection fraction < or =40% (RR = 0.42; 95% confidence interval 0.22 to 0.79). Thus, patients with depressed ejection fraction and continued inducibility of sustained ventricular tachycardia despite oral amiodarone loading have a poor prognosis. In such patients, ICDs are associated with a 58% reduction in total cardiac mortality.
Aged↗
Risk of thromboembolism in chronic atrial flutter.
Anticoagulant therapy is not conventionally used in the treatment of patients with atrial flutter. This recommendation has been based on sparse clinical experience, and recent preliminary reports suggest a significant risk of thromboembolism for these patients. A retrospective study was undertaken to assess the frequency of thromboembolic events as well as potential risk factors for these events in a cohort of patients with atrial flutter referred for radiofrequency ablation treatment. Eighty-six consecutive patients with a primary diagnosis of atrial flutter were evaluated. A history of embolic events was noted in 12 of 86 patients (14%) with atrial flutter, with an annual risk of approximately 3%. There were no differences in the prevalence of coronary artery disease, cardiomyopathy, valvular disease, or atrial fibrillation between the 2 groups of patients having an embolic event and those of patients without embolic events. Left ventricular function and left atrial size were also similar between the 2 groups. The only significant risk factor was hypertension (p < 0.05). However, in a regression model with other clinical variables (i.e., age, gender, left atrial size, presence or absence of any cardiac disease, length of time in flutter, left ventricular function, type of flutter, flutter cycle length, type of secondary arrhythmias) no significant predictors were found. Patients with transient ischemic attacks or pulmonary emboli were then excluded from the analysis in order to compare the thromboembolic risk in the present study to that reported in major atrial fibrillation trials. The overall risk becomes 7% (6 of 86), which over a mean follow-up period of 4.5 years yields an annual risk of approximately 1.6%. Although this risk is only 1/3 of that for patients with atrial fibrillation, this risk is higher than previously recognized for patients with chronic atrial flutter. Anticoagulant therapy should be seriously considered for these patients.
Adult↗
Biophysical characteristics of radiofrequency lesion formation in vivo: dynamics of catheter tip-tissue contact evaluated by intracardiac echocardiography.
During clinical radiofrequency catheter ablation a wide range of delivered power may be necessary to achieve success despite an apparently stable catheter position on fluoroscopy. The purpose of this study was to use intracardiac echocardiography to characterize the relation between catheter tip-tissue contact and the efficiency of heating during applications of radiofrequency energy in vivo and to determine whether intracardiac echocardiography could be used prospectively to improve tissue contact. A closed-loop temperature feedback control system was used during radio-frequency applications at five anatomic regions in the right atrium of 15 anesthetized dogs to ensure achievement of a predetermined temperature (70 degrees C) at the catheter tip thermistor by automatic adjustment of delivered power (maximum 100 W). The efficiency-of-heating index was defined as the ratio of steady-state temperature (degrees Celsius) to power (watts). Two-dimensional intracardiac echocardiography was used to evaluate movement of the catheter tip relative to the endocardium. Perpendicular contact was scored as good, average, or poor and lateral catheter sliding as < 2, 2 to 5, or > 5 mm. Two groups of animals were included: group 1, in which tissue contact was guided by fluoroscopic and electrographic criteria for stability of contact, with intracardiac echocardiography used simply to observe the application; and group 2, in which tissue contact was guided by intracardiac echocardiography. Of 66 applications, 18 (27.3%) had poor perpendicular contact on echocardiography, and 12 (18.2%) demonstrated lateral sliding of > 5 mm even though they had been considered to have good tissue contact by fluoroscopic and electrographic criteria. Perpendicular catheter contact and anatomic location were shown to be independently related to the efficiency-of-heating index. Applications with good perpendicular contact had a significantly higher efficiency-of-heating index and a significantly greater lesion size than those with average or poor contact. The percentage of applications having good perpendicular tissue contact and the lesion size were significantly greater when tissue contact was guided by intracardiac echocardiography compared with fluoroscopic and electrographic guidance. This study demonstrates that variations in catheter tip-tissue contact account for differences in the efficiency of tissue heating, independently of the anatomic site of the application. Poor tissue contact was observed by intracardiac echocardiography and confirmed by indexes of tissue heating in approximately one third of radiofrequency applications despite a fluoroscopic appearance and electrographic morphologic appearance suggestive of good tissue contact. There was a significant correlation between echocardiographic evaluation of tissue contact, parameters of tissue heating (efficiency-of-heating index), and lesion size. In addition, intracardiac echocardiography could be used prospectively to improve the percentage of good contact applications and increase the lesion size.
Analysis of Variance↗
The laboratory evaluation and role of catheter ablation for patients with atrial flutter.
The anatomic substrate for atrial flutter has now been recognized, and improved methods for catheter ablation have been developed. Using mapping techniques such as entrainment mapping, recognizing the different types of flutter that can occur, and testing for conduction block with pacing after ablation, long-term cure of atrial flutter can be achieved in most patients with catheter ablation. Not only is catheter ablative cure of atrial flutter the treatment of choice for drug-refractory patients, but also may now be offered as an alternative to drug therapy.
Atrial Flutter↗