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PubMed1978

Electrophysiological studies in four patients with atrial flutter with 1:1 atrioventricular conduction.

Electrophysiological studies of atrioventricular conduction during rapid atrial overdrive pacing and during programmed premature atrial stimulation are reported in four patients with an unusually rapid 1:1 ventricular response to atrial flutter (ventricular rates 240 to 310 per minute). Second-degree AV block development during atrial overdrive pacing at rates well below those during spontaneous atrial flutter. Although none of the four patients showed evidence of pre-excitation on the standard 12-lead electrocardiogram, evidence suggesting a partial AV nodal bypass was demonstrated at electrophysiological study in one case. It is postulated that the profile of the atrial wavefront presented to the normal AV node by atrial flutter differs from that during high right atrial pacing and may account for the lower ventricular rates achieved during high right atrial overdrive pacing than during spontaneous atrial flutter in the remaining three cases.

Adult↗
PubMedDate not supplied

[Double tachyarrhythmia: left anterior fascicular ventricular tachycardia associated with atrial flutter and fibrillation. Report of a case].

A patient with episodes of palpitation in whom the electrocardiogram showed a right bundle branch (RBBB) configuration and right axis deviation underwent electrophysiologic study and radiofrequency ablation. Left ventricular endocardial mapping during ventricular tachycardia (VT) identified the earliest ventricular activation in the anterolateral wall of the left ventricle. The fused Purkinje potential was recorded at that site, and preceded the QRS complex by 47 mseg, with pace mapping showing an optimal match between the paced rhythm and the clinical VT. The stimulus to QRS time was equal to the Purkinje potential-QRS time. Several radiofrequency lesions were applied in this region, one of them resulted with termination of the tachycardia. Following delivery of this lesion the ventricular tachycardia couldn't be induced either at baseline or during isoproterenol infusion. During VT, atrial fibrillation and atrial flutter were observed, cardioversion was performed reverting to sinus rhythm.

Atrial Flutter↗
PubMed1992

Sudden cardiac death in calves with experimental heavy infection of Strongyloides papillosus.

For obtaining the preliminary data on the pathogenesis of sudden death in calves naturally heavily infected with Strongyloides papillosus, we monitored 8 Holstein calves experimentally infected with the larvae on electrocardiographic and pneumographic changes. Six calves died suddenly on days 11 to 17 after infection. Sinus tachycardia had been recorded continuously since 1 to 6 days before death. Heart rates increased gradually until death. Since 1 or 2 days before death, various patterns of tachyarrhythmia and bradyarrhythmia had been observed among patterns of sinus tachycardia. Arrhythmias included serious ventricular premature beat, paroxysmal ventricular tachycardia, complete atrioventricular block and so on. The terminal pattern observed suddenly in all of the cases was ventricular arrhythmias consisting of serial ventricular tachycardia, flutter and fibrillation, which were followed by respiratory arrest. Abnormal pneumograms were not obtained before the terminal ventricular fibrillation. Two of 8 calves recovered from the infection, only one of which showed sinus arrest and the second degree of atrioventricular block transiently. We concluded that calves heavily infected with the larvae died due to sudden cardiac arrest.

Animals↗
PubMed1993

Catheter ablation for cardiac arrhythmias.

With the introduction of radiofrequency energy, catheter ablation has become an established technique for managing many cardiac rhythm disturbances. High efficacy and safety have been reported for accessory pathway ablation, selective fast and slow atrioventricular nodal pathway ablation to eliminate atrioventricular nodal reentrant tachycardia (while preserving atrioventricular conduction), atrioventricular junctional ablation to control the ventricular response to atrial tachyarrhythmias, ablation of the right bundle branch to eliminate bundle branch reentrant ventricular tachycardia, and ablation of the site of tachycardia origin in patients with ventricular tachycardia unassociated with structural heart disease. In addition, there has been active investigation into ablation techniques for more complex arrhythmias such as atrial tachycardia, atrial flutter, and ventricular tachycardia associated with structural heart disease.

Arrhythmias, Cardiac↗
PubMed1991

Acute and long-term efficacy of oral propafenone in patients with ventricular tachyarrhythmias.

The class Ic antiarrhythmic agent propafenone was studied by repeated electrophysiologic testing in 54 patients (43 male, aged 54 +/- 10 years, mean ejection fraction of 37.3 +/- 16.9%) with ventricular tachyarrhythmias. Forty patients (74%) had coronary artery disease. Programmed ventricular stimulation (S2, S2S3 during sinus rhythm and/or during S1S1 = 500, 430, 370, and 330 ms) off antiarrhythmic drugs induced sustained ventricular tachycardia, flutter, or fibrillation in all patients. After 450-900 mg of oral propafenone/day for 4-7 days, 51 patients were restudied. In the remaining three patients, spontaneous ventricular tachycardia occurred on drug therapy. Tachycardia induction was suppressed in 9 of 51 patients restudied (18%) and rendered more difficult to induce (basic stimulation drive greater than or equal to 40 beats/min higher than at control study) in another 7 patients (14%) (overall efficacy of 31%). The tachycardia rate decreased from 220 +/- 43 to 177 +/- 44 beats/min (p less than 0.01). The right ventricular effective refractory period increased from 232 +/- 22 to 252 +/- 22 ms (p less than 0.001). Responders to propafenone therapy had higher rates of inducible ventricular tachycardia at control (greater than 230 beats/min: 43%; less than or equal to 230 beats/min: 21%; p less than 0.05), higher ejection fractions, and lower left ventricular end-diastolic pressures than nonresponders. Eleven of the 16 patients showing a positive response to propafenone therapy in electrophysiologic testing were discharged on propafenone alone. During follow-up (17 +/- 12 months), nine patients remained free from ventricular tachycardia, one patient had a relapse, and one patient died of noncardiac death.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗
PubMed1979

Computer diagnosis of supraventricular and ventricular arrhythmias. A new esophageal technique.

Computerized arrhythmia monitors recognize only a few of the significant arrhythmias and generally fail to detect arrhythmias of supraventricular origin. This is because conventional surface leads, which are sufficient for QRS recognition, are highly inadequate for automated P-wave detection. A new two-lead system, which includes a swallowable capsule-electrode for esophageal monitoring of atrial activity, is used in an on-line arrhythmia monitor. Three interval measurements (AA, AR and RR) and a QRS shape measurement provide the foundation for a detailed interpretation of each beat. Building on the single-beat analysis, a contextual diagnostic algorithm then recognizes and reports on-line the following arrhythmias: couplets, bigeminy, trigeminy, ventricular tachycardia, supraventricular tachycardia, atrial flutter, atrial fibrillation, ventricular tachycardia with retrograde conduction to the atria, first-degree block, second-degree block, Wenckebach periodicity, advanced block, third-degree block and sinus bradycardia.

Arrhythmias, Cardiac↗
PubMed1994

[Drug prevention of recurrence in paroxysmal and chronic atrial fibrillation].

In many patients with paroxysmal or chronic atrial fibrillation, long-term antiarrhythmic drug therapy is performed to prevent recurrences of atrial fibrillation or to reduce the incidence of paroxysmal attacks of atrial fibrillation. The results of several studies on the efficacy of antiarrhythmic drugs in patients with paroxysmal atrial fibrillation have revealed that the incidence of recurrent attacks of atrial fibrillation can be reduced and the duration of arrhythmia free intervals can be prolonged by antiarrhythmic drug therapy. However, complete prevention of atrial fibrillation can be achieved only in a minority of patients. At present, there is no evidence that antiarrhythmic drug treatment of patients with paroxysmal atrial fibrillation might worsen the prognosis by an increase in cardiac mortality induced by antiarrhythmic drugs. In patients with chronic atrial fibrillation, the recurrence rate of the arrhythmia can be significantly reduced by antiarrhythmic drug therapy within the first year of treatment. However, there is evidence that antiarrhythmic drugs might worsen the prognosis when compared to patients with atrial fibrillation not treated with antiarrhythmic drugs. Accordingly, the indication for antiarrhythmic drug therapy to prevent recurrences in patients with chronic atrial fibrillation has to be made restrictively and should be largely based on the symptomatic status of the patients. Antiarrhythmic drug therapy seems to be indicated only in patients who are significantly symptomatic or compromised by the arrhythmia. In patients without or with only mild symptoms, medical therapy with the aim to slow the ventricular response with digitalis, calcium antagonists or betablocking agents seems to be more adequate. Currently, with respect to efficacy and safety, there is no antiarrhythmic drug that has been proved to be superior to others and that can thus be recommended as the drug of first choice for patients with paroxysmal or chronic atrial fibrillation to prevent recurrences. The choice of the optimal antiarrhythmic drug should be made by taking individual factors (e.g., etiology of the arrhythmia, patient compliance, liver and renal function of the patient, additional medical therapy) into account. Major problems during long-term antiarrhythmic drug therapy may arise in patients with pre-existing sinus node dysfunction or conduction disturbances of the atrioventricular node. In addition, the conversion of atrial fibrillation with relatively slow ventricular rates to the atrial flutter with fast ventricular rates that is occasionally observed during treatment with class I-antiarrhythmic drugs may complicate long-term therapy.(ABSTRACT TRUNCATED AT 400 WORDS)

Anti-Arrhythmia Agents↗
PubMed1993

[Cardiac arrest reversed: causes and treatments].

The aim of this study was to report the probable mechanism of resuscitated cardiac arrest without acute myocardial infarction. Fifty-seven cases were recensed but the arrest was only documented in 44 subjects. Systematic non-invasive investigations and programmed stimulation showed that the diagnosis of cardiac arrest was probably false in 5 patients and, in the others, that a ventricular arrhythmia was probably the cause (63%). The occurrence of cardiac arrest under antiarrhythmic therapy may reveal an underlying abnormality requiring specific therapy (3/8). The absence of cardiac disease did not exclude the risk of VF (3 cases). When reproducible, ventricular arrhythmias were present during programmed stimulation, the prognosis was good if the arrhythmia could not be induced under antiarrhythmic therapy. It was easier to find an effective treatment for inducible ventricular fibrillation-flutter (13/17) than for inducible ventricular tachycardia (7/17). The prognosis was poor if the arrhythmia was unchanged during programmed stimulation under antiarrhythmic therapy and non-pharmacological treatment was required.

Adolescent↗
PubMed1984

Cardiac rhythm and conduction in Duchenne's muscular dystrophy: a prospective study of 20 patients.

This study was designed to determine the types and prevalence of rhythm and conduction disturbances in Duchenne's muscular dystrophy, and examine the results in light of known morphologic abnormalities of the myocardium and the small coronary arteries, and in the context of left ventricular function, regional wall motion, mitral valve prolapse and left atrial size. The observed disorders of impulse and conduction extended from the sinus node to the His-Purkinje system. Rhythm disturbances included persistent and labile sinus tachycardia (gradual or abrupt), sinus arrhythmia, sinus pauses, atrial ectopic beats, atrial ectopic rhythm, junctional rhythm, atrial flutter and ventricular premature beats (uniform, multiform, bigeminal and repetitive). Disorders of conduction included abnormal intraatrial or interatrial conduction, Mobitz type I block, nonconducted atrial premature beats, short PR interval, right ventricular conduction delay and rightward axis compatible with left posterior fascicular block. The role of dystrophic involvement of specialized conduction tissues and of the small vessel coronary arteriopathy remains speculative, but mitral valve prolapse, left atrial size and left ventricular size, function and regional wall motion played no discernible part in the genesis of the rhythm and conduction disturbances. Except for end-stage atrial flutter, these disturbances were not clinically deleterious.

Adolescent↗
PubMed1987

Randomized placebo-controlled trial of propafenone for treatment of atrial tachyarrhythmias after cardiac surgery.

Fourteen patients with atrial fibrillation or flutter and a ventricular rate of greater than or equal to 120 beats/min occurring after cardiac surgery entered a double-blind placebo-controlled conditional crossover trial of intravenous propafenone. Patients randomly received either propafenone (2 mg/kg body weight) or placebo during a 10 minute intravenous infusion. If 20 minutes after the initiation of this infusion there was no conversion to sinus rhythm, the patient received a second intravenous infusion over 10 minutes (either propafenone or placebo, whichever was not given first). The electrocardiogram was recorded continuously throughout the study. Fourteen patients received propafenone and 10 received placebo. No patient's rhythm converted to sinus rhythm after placebo. In six patients (43%) (p less than 0.001), the arrhythmia converted to sinus rhythm between 5 and 10 minutes after the end of the propafenone infusion. After propafenone, the ventricular response to atrial fibrillation or flutter decreased significantly from 141.6 +/- 15.2 to 116.0 +/- 15.5 beats/min. Ventricular rate did not change after placebo. The mean propafenone plasma concentration was 3.46 +/- 2.17 mg/liter. The only side effect of propafenone noted was a decrease in systolic blood pressure of 9 +/- 9 mm Hg. Propafenone was useful for management of atrial fibrillation after cardiac surgery both for control of rapid ventricular response and for conversion to sinus rhythm.

Adult↗
PubMed1986

Long-term management of bradyarrhythmias following open heart surgery: surgical A-V block and sick sinus syndrome after surgery for secundum atrial septal defects treated with permanent cardiac pacing.

Postoperative clinical findings from 25 patients with surgical A-V block and 12 with SSS following surgery for ASD who received permanent pacemakers were analyzed in order to consider the long-term management of postoperative bradyarrhythmias. Surgical A-V block: Episodes of Adams-Stokes were observed in 11/25 patients before pacemaker implantation, and in 6 of these (55%) the onset of episodes occurred more than a year after open heart surgery. Of 8 cases for which ECG's during Adams-Stokes were available, 2 had bifascicular or trifascicular block which progressed to complete A-V block below the His bundle. The 6 others (75%) had ventricular tachycardia or ventricular flutter-fibrillation during Adams-Stokes. 2 of these had blocks above the His bundle. 4/25 had improvement of complete A-V block within a month. Following pacemaker implantation, 3 died of heart failure and 3 of sudden death. 5 year survival was 70%. Therefore, surgical A-V block requires careful long-term management, and the presence of ventricular tachyarrhythmias as well as the location of block are important predictors of patient risk. SSS after surgery for ASD: 10/12 patients had Adams-Stokes, of which 6 (60%) had initial onset over 5 years after surgery, and 9 had paroxysmal atrial flutter and fibrillation which coincided with the onset of Adams-Stokes. 3 of 7 patients (42%) for whom preoperative ECG's were available had sinus bradycardia. Thus, SSS after ASD surgery may be preceded by preoperative deterioration of sinus node function and succeeded by late onset of Adams-Stokes, necessitating pre- and postoperative assessment of sinus node function. The presence of atrial tachyarrhythmias also serves as an important indicator of the severity of SSS after ASD surgery. The onset of Adams-Stokes varied by patient over a wide range of time, emphasizing the need for careful long-term follow-up. Clinical symptoms and prognosis were affected by tachyarrhythmias as well as the severity of the bradycardia. Therefore, the presence of ventricular/atrial tachyarrhythmias is an important factor in the long-term management of postoperative bradyarrhythmias.

Adams-Stokes Syndrome↗
PubMed1994

The value of rate regularity and multiplicity measures to detect ventricular tachycardia in the presence of atrial fibrillation or flutter.

The predominant cause of inappropriate therapy by implantable antitachycardia devices with pacing and nonpacing cardioverter defibrillators, is mistaking a fast ventricular response during atrial fibrillation or flutter with true ventricular tachycardia (VT). The distinction between these arrhythmias is an important consideration in addressing the problem of reducing false-positives in detection mechanisms for implantable devices. Dual chamber analysis that examines atrial and ventricular event ratios has been proposed as a solution to this problem, but would still fail in distinguishing paroxysmal VT requiring treatment from a fast but otherwise benign ventricular response during atrial fibrillation or flutter. In this study, two methods for discriminating these tachyarrhythmias were evaluated. Method 1 examined ventricular rate and rate regularity as a method for VT detection. Method 2 combined rate and regularity as well as an additional multiplicity criterion for recognition of atrial flutter with a fast ventricular response. In 20 patients, Method 1 had 100% sensitivity of VT detection and 80% specificity for detection of atrial fibrillation or flutter. Method 2 had 90% sensitivity and 90% specificity. These results suggest that use of these algorithms in future implantable devices would result in a decrease in false-positive device therapies.

Algorithms↗
PubMed1996

Regional left atrial stasis during atrial fibrillation and flutter: determinants and relation to stroke.

OBJECTIVES: This study sought to 1) determine the location of left atrial stasis during atrial arrhythmia; 2) define the degree of stasis associated with significant risk of stroke; and 3) identify clinical or transthoracic echocardiographic data useful for predicting left atrial stasis. BACKGROUND: Prior studies suggest that stroke during atrial arrhythmia is related to stasis in either the body of the left atrium or the appendage. Recent data indicate that appendage stasis is associated with appendage thrombus formation, but stroke during atrial arrhythmia occurs frequently in the absence of appendage stasis. METHODS: Blood flow velocity was measured in multiple sites in the body of the left atrium and in the appendage by transesophageal pulsed wave Doppler echocardiography in 89 patients with atrial fibrillation or flutter. Regional velocities were related to the frequency of probable embolic stroke and to clinical and transthoracic echocardiographic variables. RESULTS: The lowest velocity region was either the posterior left atrium or the appendage. Stroke frequency increased progressively and steeply with velocity < 15 cm/s in either region; this cutoff value had an 87% sensitivity and 40% specificity for stroke. Factors related to stasis were low left atrial ejection fraction, mitral regurgitation < 3+, fibrillation (vs. type I flutter), left ventricular dilation and mitral valve area < 2.0 cm2. CONCLUSIONS: Posterior left atrial stasis appears to be as important as appendage stasis for the risk of stroke, which increases steeply with lower blood flow velocity in either region. Patients likely to have severe stasis during atrial arrhythmia are those with left ventricular dilation and low atrial ejection fraction accompanying left atrial dilation. Direct measurement of atrial velocity by transesophageal echocardiography appears to be useful for the identification of patients at risk for stroke during atrial arrhythmia.

Aged↗
PubMed1994

Patterns of catheter ablation practice in the United States: results of the 1992 NASPE survey. North American Society of Pacing and Electrophysiology.

Any conclusion drawn must be made within the context of all the limitations inherent in a voluntary retrospective survey. The primary purpose of this survey is to provide a general picture of current catheter ablative procedure practiced in the United States. This is felt to be of value in calling attention to significant trends and to highlight those areas in which improvement is needed. Improvement may be required in terms of operator experience as well as improved catheters and energy delivery systems. The striking finding was a plateau in total number of procedures from 1991 to 1992. The decline in numbers of patients undergoing ablation of accessory pathways was more than compensated for by impressive growth in numbers of patients undergoing ablative procedures for atrioventricular nodal reentry, atrial tachycardia/atrial flutter, and ventricular tachycardia. The ablative data suggest that continued improvements are needed for successful ablation of patients with right-sided accessory pathways. The anatomy of the tricuspid annulus makes for difficulty in achieving catheter stability and this report highlights the need for better catheters designed for right-sided pathway ablation. Equally concerning is the incidence of procedure related deaths (0.2%) and significant complications (2.1%) for patients with accessory pathways. This is no doubt related to the need for left heart catheterization in the majority of patients. The latter involves either retrograde aortic passage of the relatively stiff ablation catheters or use of transseptal puncture. In addition, we found that 35 of the 164 centers performed less than 20 procedures a year and low volume centers had a higher incidence of complications.(ABSTRACT TRUNCATED AT 250 WORDS)

Arrhythmias, Cardiac↗
PubMed2000

Dual chamber arrhythmia detection in the implantable cardioverter defibrillator.

INTRODUCTION: Dual chamber implantable cardioverter defibrillator (ICD) technology extended ICD therapy to more than termination of hemodynamically unstable ventricular tachyarrhythmias. It created the basis for dual chamber arrhythmia management in which dependable detection is important for treatment and prevention of both ventricular and atrial arrhythmias. METHODS AND RESULTS: Dual chamber detection algorithms were investigated in two Medtronic dual chamber ICDs: the 7250 Jewel AF (33 patients) and the 7271 Gem DR (31 patients). Both ICDs use the same PR Logic algorithm to interpret tachycardia as ventricular tachycardia (VT), supraventricular tachycardia (SVT), or dual (VT+ SVT). The accuracy of dual chamber detection was studied in 310 of 1,367 spontaneously occurring tachycardias in which rate criterion only was not sufficient for arrhythmia diagnosis. In 78 episodes there was a double tachycardia, in 223 episodes SVT was detected in the VT or ventricular fibrillation zone, and in 9 episodes arrhythmia was detected outside the boundaries of the PR Logic functioning. In 100% of double tachycardias the VT was correctly diagnosed and received priority treatment. SVT was seen in 59 (19%) episodes diagnosed as VT. The causes of inappropriate detection were (1) algorithm failure (inability to fulfill the PR<RP condition in atrial tachyarrhythmias with 1:1 AV conduction, and far-field R wave sensing intermittently present during sinus tachycardia); (2) programming settings (atrial fibrillation/atrial flutter with ventricular rate above the SVT limit); and (3) algorithm limitations (atrial tachycardia with ventricular rate around the shortest programmable SVT limit and SVT redetection following VT therapy). Programming measures improved detection ability in 13 of 59 of inappropriately detected arrhythmias. CONCLUSION: Dual chamber detection algorithms evaluated in a subset of diagnostically difficult arrhythmias allow safe detection of double tachycardias but require further extension and programmability to improve VT:SVT discrimination rules.

Adult↗
PubMed1984

Utility of the filtered bipolar esophageal lead in the diagnosis of arrhythmias.

Electrophysiologic study was performed in 25 patients with tachycardia or bradycardia attacks. The coronary sinus (CS) and filtered bipolar esophageal electrograms were recorded simultaneously to compare the phase of atrial activations. During sinus rhythm and high right atrial pacing, the esophageal and proximal CS atrial activations were nearly simultaneous but earlier by 26 +/- 5 msec on the average than the distal CS atrial activations. During reciprocating tachycardia due to reentry using a left-side accessory atrioventricular pathway for retrograde conduction the esophageal and CS atrial activations occurred earlier than the low septal right atrial activation, so the esophageal lead can be used as a substitute for the CS lead to clarify the eccentric retrograde atrial activation sequence. By using the filtered bipolar esophageal lead, the interval from Q wave on the surface electrocardiogram to the first rapid deflection in the esophageal atrial activation (Q-AESO interval) was measured in 15 patients with supra-ventricular tachycardia. All patients with reciprocating tachycardia due to reentry using a left side accessory atrioventricular pathway had Q-AESO intervals between 100 to 130 msec and four of five patients with a right side accessory atrioventricular pathway for retrograde conduction had Q-AESO intervals between 130 to 150 msec. In contrast, all patients with reentry in the atrioventricular node had Q-AESO intervals between 30 to 60 msec. The esophageal lead is also of value in the prompt diagnosis of atrial flutter and ventricular tachycardia, since the esophageal electrograms readily reveal the relationship between atrial and ventricular activations. In conclusion, the filtered bipolar esophageal lead provides a non-invasive method for the quick diagnosis of various arrhythmias.

Adult↗