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Biomedical subjects

F E Marchlinski

Publications and source records attributed to F E Marchlinski.

At least 163 records · Page 9Linked to original sources
PubMed1986

Electrocardiographic response of digoxin-toxic fascicular tachycardia to Fab fragments: implications for tachycardia mechanism.

The electrocardiographic response of digoxin-induced fascicular tachycardia to Fab fragments was evaluated in two patients. In addition, we documented the response of the fascicular tachycardia to spontaneous premature ventricular depolarizations during different tachycardia rates, the response to a nonsustained episode of ventricular tachycardia, and the mode of spontaneous initiation and termination of short-lived episodes of the tachycardia during the treatment process. The following findings were noted: slowing of the tachycardia in response to Fab administration; change in the morphologic characteristics of the tachycardia from multiform to uniform; resetting of the tachycardia by spontaneous premature ventricular depolarization with the return cycle equal to the observed tachycardia cycle length; acceleration of the tachycardia in response to five beats of a faster nonsustained ventricular tachycardia; and initiation and termination of the tachycardia, both by spontaneously occurring premature ventricular depolarizations and in the absence of premature ventricular depolarizations. Both tachycardias resolved completely within 20 and 40 minutes, respectively, of Fab administration. We conclude that Fab administration can promptly resolve fascicular tachycardias precipitated by digoxin toxicity and that the observed electrocardiographic phenomena strongly suggest triggered activity as the electrophysiologic mechanism of fascicular tachycardia in man.

Aged↗
PubMed1986

Electrocardiographic changes after cardioversion of ventricular arrhythmias.

To evaluate rhythm and QRS-T changes after cardioversion of induced ventricular arrhythmias, 56 patients underwent continuous three-lead and serial 12-lead electrocardiographic monitoring for 15 min after 77 cardioversions. Fifty patients were cardioverted externally and nine internally with an implanted automatic cardioverter/defibrillator. Initial energy for external cardioversion was 200 Wsec in 57 of 64 arrhythmia episodes. Two hundred watt-seconds of energy effectively terminated 41 of 44 episodes of ventricular tachycardia and six of 13 episodes of ventricular fibrillation (p less than .001). Early bradycardia (mean cycle length greater than or equal to 1200 msec during the first 5 sec) occurred after 17 of 64 external and two of 13 internal cardioversions (p = NS) in a total of 16 patients. Bradycardia persisted at 10 sec after cardioversion in nine patients. Early bradycardia was associated with the need for multiple cardioversions to terminate the arrhythmia (six of 10 multiple cardioversions vs 13 of 67 single cardioversions, p less than .05) and the presence of inferior myocardial infarction (eight of 16 patients with vs eight of 40 patients without inferior infarction, p less than .05). Supraventricular tachycardia (cycle length less than or equal to 500 msec) occurred after 19 of 64 external and six of 13 internal cardioversions (p = NS). Nonsustained ventricular tachycardia (4 to 40 beats) was observed after seven external cardioversions, with three episodes lasting 3 sec or more.(ABSTRACT TRUNCATED AT 250 WORDS)

Arrhythmias, Cardiac↗
PubMed1986

Endocardial catheter mapping in patients in sinus rhythm: relationship to underlying heart disease and ventricular arrhythmias.

Catheter mapping during sinus rhythm was performed in 132 patients with coronary artery disease and 26 patients with congestive noncoronary cardiomyopathy. Each of the patients had a clinical history of one of the following: no ventricular arrhythmia, nonsustained ventricular tachycardia, cardiac arrest, or sustained ventricular tachycardia. The characteristics of the endocardial electrogram and other measured indexes of slow endocardial conduction were compared between patients with different types of disease and in different arrhythmia groups to determine if differences existed. The cardiomyopathic group had a higher percent of normal endocardial electrograms than the coronary artery disease group, with no evidence of slow endocardial conduction. The sustained ventricular tachycardia group exhibited a greater percent of abnormal endocardial electrograms and more evidence of slow endocardial conduction, distinguishing this group from the three other arrhythmia groups. We conclude the following: The underlying electrophysiologic substrate varies in patients with different ventricular arrhythmias. It is therefore inappropriate to analyze all patients with ventricular arrhythmias as a single group. Patients with congestive noncoronary cardiomyopathy, regardless of the type of their arrhythmia, have a relatively normal endocardium. Those patients with serious ventricular arrhythmias should not be considered candidates for surgery directed at removing abnormal endocardium.

Aged↗
PubMed1986

Resetting response patterns during sustained ventricular tachycardia: relationship to the excitable gap.

We analyzed the resetting response (a noncompensatory pause after electrical stimulation) during 37 hemodynamically tolerated ventricular tachycardias (VTs) induced by programmed electrical stimulation in 32 patients with chronic coronary artery disease. The mean cycle length of VT was 369 +/- 59 msec. Single extrastimuli were delivered at the right ventricular apex during all 37 VTs, and double extrastimuli were delivered at the same site during 23 VTs. The resetting response pattern was considered increasing, decreasing, or flat if the return cycle increased, decreased, or remained constant in response to progressively shorter coupling intervals of the extrastimuli. Ten VTs had an increasing pattern and nine a flat pattern. In 11 VTs the pattern was mixed (flat at longer coupling intervals and increasing at shorter ones), and in the remaining seven the pattern could not be defined. No VT had a decreasing pattern. The mean duration of the resetting interval (range of coupling intervals resulting in resetting) was 66 +/- 45 msec, or 17% of the cycle length of VT. VT with a mixed pattern had longer resetting intervals than VT with an increasing pattern (102 +/- 34 vs 64 +/- 40 msec; p less than .035); however, cycle lengths of VT were similar (370 +/- 58 vs 386 +/- 86, p = NS). An excellent correlation was observed between the shortest return cycles in response to single and double extrastimuli (r = .99), with a mean difference of 5 msec. The cycle length of VT exceeded the return cycle (measured to the QRS onset) during 15 VTs (41%).(ABSTRACT TRUNCATED AT 250 WORDS)

Cardiac Pacing, Artificial↗
PubMed1986

Amiodarone versus amiodarone and a type IA agent for treatment of patients with rapid ventricular tachycardia.

Induction of rapid ventricular tachycardia or fibrillation during therapy with amiodarone is associated with an increased risk of sudden death. To determine whether the addition of a type IA antiarrhythmic agent to therapy would improve outcome, 37 patients in whom ventricular tachyarrhythmia of a cycle length less than 350 msec was induced after 14 +/- 2 days of amiodarone were randomly assigned to therapy with amiodarone alone (group 1, 20 patients) or amiodarone plus type IA agent (group 2, 17 patients). Type IA therapy consisted of procainamide in 13 patients and quinidine in four procainamide-intolerant patients. To assess the short-term effects of a type IA agent on inducibility of ventricular tachyarrhythmia, cycle length, and hemodynamic tolerance, 16 of 20 patients in group 1 and all patients in group 2 underwent repeat programmed stimulation after the intravenous administration of procainamide during amiodarone therapy (mean procainamide serum concentration 7.2 +/- 2.0 micrograms/ml). Procainamide prevented induction of sustained arrhythmia in only two of 33 patients. Procainamide increased the cycle length of induced ventricular tachycardia from 283 +/- 30 to 352 +/- 46 msec (p less than .001). After the addition of procainamide, 16 of 31 patients vs 10 of 37 patients on amiodarone alone had an induced arrhythmia that was tolerated hemodynamically (p less than .05). There were no differences between groups 1 and 2 with respect to patient or arrhythmia characteristics, response to short-term procainamide, or duration of follow-up. The mean follow-up for all patients was 14 +/- 10 months.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1986

The automatic implantable cardioverter-defibrillator: efficacy, complications, and device failures.

Twenty-six patients with refractory ventricular arrhythmias received the automatic implantable cardioverter-defibrillator. A patch lead only was placed during arrhythmia surgery in 7 other patients. During 13 +/- 6 (SD) months, the device discharged in 10 patients because of a sustained ventricular arrhythmia. No sudden deaths occurred. There were 31 complications in 17 patients, including postoperative refractory heart failure, coronary artery erosion, subclavian vein thrombosis, postoperative stroke after conversion of atrial fibrillation, atelectasis with pneumonia, symptomatic pleural effusions, and infection at the generator site. The cardioverter-defibrillator discharged in 9 asymptomatic patients, failed to terminate ventricular fibrillation during postoperative testing in 3 patients, and had premature battery failure in 4 patients. Tachycardia slowing during chronic amiodarone therapy and unipolar ventricular pacing during ventricular fibrillation precluded or delayed arrhythmia sensing. Thus, the cardioverter-defibrillator can be life saving, but its potential complications and interactions with antiarrhythmic drugs and pacemakers must be considered at patient selection.

Adolescent↗
PubMed1985

Entrainment of ventricular tachycardia by atrial depolarizations.

Four patients in whom rapid atrial pacing resulted in transient entrainment of a sustained ventricular tachycardia (VT) are reported. Ventricular fusion was seen in 3 of the 4. The following new observations were made: (1) A single atrial depolarization resulted in ventricular fusion and resetting of a VT, while atrial pacing at a faster rate entrained the same VT but without detectable fusion. This suggests that fusion during entrainment may be a rate-dependent phenomenon. (2) The interval between the last paced beat and the first nonpaced VT beat was different from the pacing cycle length in 3 patients. Two mechanisms accounted for this: the initial forces of each entrained QRS occurring as a result of the pacing wavefront, with fusion taking place only during the terminal forces, and the last entrained cycle exceeding the pacing cycle length by an amount related to the nonfused portion of the QRS, and delay in the presumed reentrant circuit responsible for the tachycardia. One VT was entrained with atrial pacing while ventricular pacing at the same rate resulted in termination, suggesting "site specificity" for termination. It is concluded that entrainment can occur without the criteria previously described as characteristic of it and that additional phenomena may be observed after stimulation that further support reentry as the mechanism of VT.

Adult↗
PubMed1985

Subendocardial resection for sustained ventricular tachycardia in the early period after acute myocardial infarction.

One hundred nineteen patients with drug-refractory ventricular tachycardia (VT) underwent mapping-guided subendocardial resection for control of their arrhythmias from 3 weeks to 10 years after acute myocardial infarction (AMI). Patients were separated into 2 groups: those treated early (within 4 months, group I) and those treated later (after 1 year, group II) after AMI. There were 32 patients in group I and 72 patients in group II. Both groups of patients had similar clinical, angiographic and hemodynamic characteristics. Patients in group I had VT with a shorter mean cycle length than patients in group II (322 +/- 71 vs 349 +/- 88 ms, p less than 0.05). The groups did not differ with respect to operative mortality (12% vs 7%), late mortality (31% vs 33%, mean follow-up 23 months), or frequency with which subendocardial resection without any adjunctive therapy prevented postoperative spontaneous or inducible VT (21% vs 34%). Group I was further separated into patients who underwent subendocardial resection within 1 month of AMI (n = 7) and those who underwent subendocardial resection with 2 months of AMI (n = 14). Although patients in group I were characterized by having more spontaneous morphologically distinct tachycardias, their operative mortality, total mortality and surgical success rates were comparable to those of patients in group II.(ABSTRACT TRUNCATED AT 250 WORDS)

Actuarial Analysis↗
PubMed1985

Relation of late potentials to site of origin of ventricular tachycardia associated with coronary heart disease.

Signal-averaged electrocardiograms and endocardial catheter mapping were performed in 41 patients with coronary artery disease and sustained ventricular tachycardia (VT) to determine the relation between signal-averaged late potentials (SA-LPs) and catheter-mapped late activity (CM-LA) to the site of origin of VT. The 41 patients had 79 morphologically distinct VTs. Either CM-LA or SA-LP was present during sinus rhythm in 37 of 41 patients (90%). Twenty-two out of 30 patients (73%) had CM-LA corresponding to SA-LP during normal sinus rhythm. Patients with SA-LP had a significantly greater number of sites of CM-LA, which were later and longer in duration than patients without SA-LP present during sinus rhythm. In a select group of patients, those with both SA-LP and CM-LA, the site of origin of VT was located at or adjacent to a site of CM-LA during sinus rhythm in 38 of 44 (86%); however, 36 of 78 sites (46%) of CM-LA were clearly distant from the site of origin of VT. In conclusion, CM-LA corresponding to SA-LP in patients with VT is sensitive but not specific for the site of origin of VT.

Adult↗
PubMed1985

Electrophysiologic evaluation and follow-up characteristics of patients with recurrent unexplained syncope and presyncope.

One hundred nineteen patients with unexplained syncope (82%) or presyncope (18%) underwent complete electrophysiologic study (EPS). Symptoms were recurrent in 72% of the patients. Fifty-two percent of the patients had structural heart disease. Forty-one patients had normal EPS results and 78 had electrophysiologic abnormalities (ventricular tachycardia in 31, induced atrial flutter/fibrillation in 17, vasovagal syncope in 8, hypersensitive carotid sinus syndrome in 7, supraventricular tachycardia in 6, heart block in 5 and sick sinus syndrome in 4). The presence of structural heart disease (p = 0.0033) and previous myocardial infarction (p = 0.05) were the only clinical or electrocardiographic predictors of a positive EPS response. Therapy was guided by EPS and patients were followed for 27 +/- 20 months (mean +/- standard deviation). In the patients with negative EPS results, 76 +/- 11% (mean +/- standard error) were symptom-free at follow-up, compared to 68 +/- 10% in the group with positive EPS responses. No clinical variables helped to predict remission in the absence of therapy. One patient in the negative EPS response group and 2 patients in the EPS positive group died suddenly (cumulative survival 94 +/- 4%). Total cardiovascular mortality was 13% in the positive EPS response group, and 4% in the negative EPS response group. Thus, certain clinical characteristics are helpful in selecting patients for study. Electrophysiologically guided therapy is associated with a recurrence and sudden death rate similar to an untreated control group.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1985

Value of Holter monitoring in identifying risk for sustained ventricular arrhythmia recurrence on amiodarone.

Seventy-four patients with sustained ventricular tachyarrhythmias had 22 +/- 3 hours of Holter monitoring before and after 11 +/- 6 days of amiodarone treatment. On control Holter recordings, 55 patients (group I) had frequent (more than 10 extrasystoles per hour) and/or complex (at least couplets) ventricular ectopic activity (VEA), and 19 patients (group II) had infrequent and simple VEA. A positive Holter monitor response to amiodarone was defined as a decrease in VEA by more than 85% and abolition of all complex VEA. In group I, 34 patients (62%) had a positive Holter monitor response. In group II, 16 patients (84%) had persistent, infrequent and simple VEA and 3 had frequent and/or complex VEA. During a mean follow-up of 13 +/- 12 months, 22 patients (30%) had ventricular tachycardia (VT) or sudden death. In group I, VT or sudden death occurred in 6 of 34 (18%) patients with a positive Holter monitor response and 11 of 21 (52%) with a negative Holter monitor response (p less than 0.01), and in group II, VT or sudden death occurred in 5 of 16 patients (31%) with persistent, infrequent and simple VEA. All episodes of VT or sudden death occurred after at least 2 weeks of amiodarone therapy (mean 5 +/- 6 months). The predictive accuracy of a positive Holter monitor response as an indicator for subsequent prevention of sustained ventricular tachyarrhythmias and sudden cardiac death was 82% and for a negative Holter monitor response as an indicator of tachyarrhythmia or sudden death recurrence on therapy it was 52%.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1985

Catheter mapping during sinus rhythm: relation of local electrogram duration to ventricular tachycardia cycle length.

Catheter mapping was performed during sinus rhythm in 52 patients with 102 morphologically distinct ventricular tachycardias (VT). Twenty patients had a single VT morphologic pattern. The cycle length of VT was correlated with the duration of all electrograms and various electrogram subgroups, including abnormal, fractionated, late, and longest electrograms, as well as the electrogram recorded at the site of origin of VT and at sites other than the site of origin using linear regression analysis. No correlation was found between local electrogram duration of any of these groups and VT cycle length. There was no relation regardless of whether the patient had a single or multiple morphologic patterns. Thus, the local electrogram duration measured with catheter mapping during sinus rhythm does not correlate with VT cycle length. This finding provides additional support that catheter mapping during sinus rhythm does not give sufficient information to guide localized endocardial resection for VT surgery.

Electrocardiography↗
PubMed1985

Atrial and ventricular burst pacing from a coronary sinus catheter: relation to position of radiofrequency transmitter.

A young woman with drug-refractory recurrent supraventricular tachycardia was managed by rapid atrial stimulation using a catheter positioned in the coronary sinus. During follow-up, radiofrequency activation of the pacemaker resulted in burst ventricular and/or atrial pacing, depending on the distance of the transmitter's antenna loop from the receiver. Current output was directly related to the distance of the transmitter's antenna loop from the receiver and ranged from 20 mA at a distance of 0 cm from the receiver to 1 mA at 5 cm. If possible, coronary sinus lead placement should be avoided for radiofrequency-activated atrial burst pacing given the large current output with direct contact of the transmitter's antenna loop to the implanted receiver and the risk for ventricular stimulation. Alteration of the spatial relationship between the transmitter and receiver can be used to decrease current output and prevent ventricular pacing if atrial burst pacing from the coronary sinus is desirable.

Adult↗
PubMed1985

Effects of infarction, procainamide, coupling interval, and cycle length on refractoriness of extrastimuli.

The effects of prematurity, cycle length, site of stimulation, and procainamide on ventricular refractoriness following an extrastimulus (S2) were assessed in 10 dogs with and 10 dogs without infarction. Extrastimuli were introduced at preselected coupling intervals (S1-S2) from normal right and left ventricular sites and from left ventricular sites of infarction during drive cycle lengths (S1-S1) of 350 and 250 ms. At each S1-S2 interval, the effective refractory period of S2 was determined by introducing a second extrastimulus (S3). At all stimulation sites, cycle lengths, and before and during infusion of procainamide (mean concn 18.6 +/- 3.5 micrograms/ml), shortening (greater than 10 ms change) in refractoriness was most marked over a narrow range of closely coupled S1-S2 intervals. Regardless of stimulation site, the effective refractory period of S2 was less during a cycle length of 250 ms compared with a cycle length of 350 ms. In dogs without infarction, the effective refractory periods of S2 from left ventricular sites tended to be longer than from right ventricular sites, particularly during procainamide administration. The refractory period of S2 at sites of infarction did not differ consistently from those at normal sites. Finally, at all stimulation sites and cycle lengths, procainamide prolonged refractoriness of S2 at each S1-S2 interval and blunted the total shortening in refractoriness in response to S2.

Animals↗
PubMed1985

Abnormal signal-averaged electrocardiograms in patients with nonischemic congestive cardiomyopathy: relationship to sustained ventricular tachyarrhythmias.

We assessed whether signal-averaged electrocardiography could identify patients with sustained ventricular arrhythmias in 41 patients with non-ischemic cardiomyopathy. Twelve of these patients presented with sustained ventricular arrhythmia and 29 patients had no history of sustained ventricular arrhythmias. The mean ejection fractions in the groups were 30 +/- 9% and 24 +/- 9%, respectively. Results were compared with signal-averaged electrocardiograms in 55 normal individuals. The filtered QRS duration was longest in patients with sustained ventricular arrhythmias (130.2 +/- 19.5 vs 105.0 +/- 13.1 msec in the group without sustained ventricular arrhythmia, p less than .001 and 95.9 +/- 9.1 in the normal group, p less than .001). The voltage in the last 40 msec of the filtered QRS was lower in the sustained ventricular arrhythmia group (11.3 +/- 9.3 microV) than the group without sustained ventricular arrhythmia (53.5 +/- 28.3 microV; p less than .001) or the normal group (53.7 +/- 25.2 microV; p less than .001). Eighty-three percent of patients in the sustained ventricular arrhythmia group had an abnormal signal-averaged electrocardiogram characterized by both a long filtered QRS duration and a late potential of low voltage level; only 2% of normal subjects and 14% of patients without sustained ventricular arrhythmias had an abnormal signal-averaged electrocardiogram. The signal-averaged electrocardiogram can identify patients with nonischemic congestive cardiomyopathy and sustained ventricular arrhythmias.

Adult↗
PubMed1985

Atrial arrhythmias exacerbated by theophylline. Response to verapamil and evidence for triggered activity in man.

A 75-year-old woman with acute respiratory failure due to pneumonia superimposed on bronchospastic chronic obstructive pulmonary disease and dilated cardiomyopathy developed multifocal and unifocal atrial tachycardia. Arrhythmia recurrence appeared to be dependent on reaching a critical but "nontoxic" serum theophylline concentration in the presence of high normal levels of digoxin. The arrhythmias responded to a decrease in serum theophylline concentration or to the administration of verapamil. The precipitation of the atrial arrhythmias by theophylline in the presence of digitalis, both of which may increase intracellular calcium and a dramatic response to verapamil, which inhibits calcium uptake and release, suggests that these arrhythmias may represent an example of "triggered activity" in man.

Aged↗