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Biomedical subjects

F E Marchlinski

Publications and source records attributed to F E Marchlinski.

At least 55 records · Page 3Linked to original sources
PubMed1997

Right ventricular radiofrequency ablation of ventricular tachycardia after myocardial infarction.

Radiofrequency transcatheter ablation of ventricular tachycardia in the setting of a prior myocardial infarction is typically performed with application of energy to the left ventricular endocardium. In this article, two cases are described in which successful radiofrequency transcatheter ablation of ventricular tachycardia occurred with energy delivery to the right ventricular septum after failed ablation attempts from the left ventricle. Both patients had tachycardias with a left bundle branch block morphology and markedly presystolic activity recorded from the right ventricular septum. Right ventricular septal activation mapping during ventricular tachycardia should be performed in patients with left bundle branch block tachycardia morphology and coronary artery disease to maximize efficacy of the catheter ablation procedure.

Aged↗
PubMed1997

Does the initial presentation of patients with implantable defibrillator influence the outcome?

The influence of the clinical presentation on the long-term outcome in 213 consecutive patients with ICDs, ECG storage capability, and nonthoracotomy leads, was analyzed. Sixty-six patients presented with cardiac arrest (CA), 81 patients with hemodynamically stable VT, and 66 patients with syncope (SY). Patient characteristics were: mean age CA 62, VT 61, SY 61 years; mean ejection fraction CA 31%, VT 29%, SY 30%; coronary artery disease CA 71%, VT 71%, SY 64% (all P > 0.05 Fisher's exact test); female gender CA 40%, VT 14%, SY 19% (CA vs VT and SY, P < 0.005); inducibility by programmed stimulation CA 50%, VT 84%, SY 61% (VT vs CA and SY, P < 0.001, CA vs SY, P > 0.05). During a mean follow-up of 14.5 months, 29 patients died: CA 12%, VT 14%, SY 9% (P > 0.05). Comparing Kaplan-Meier curves, no difference in the time course of overall mortality was found (log-rank P > 0.05). In the CA, VT, and SY groups, 543, 1,630, and 189 ICD therapies (including antitachycardia pacing, low energy cardioversion, and defibrillation) were observed, respectively. Actuarial analysis showed a shorter interval between implantation and first ICD therapy for VT versus CA and SY (log-rank P < 0.005). Patients presenting with VT experienced earlier and more frequent ICD therapies than patients with CA or SY independent of age, ejection fraction, and heart disease. No difference in overall mortality and time course of fatal events was observed among the three groups.

Actuarial Analysis↗
PubMed1997

ICD-antiarrhythmic drug and ICD-pacemaker interactions.

Antiarrhythmic drugs and separate bradycardia pacing systems are prescribed commonly in patients with implantable cardioverter defibrillators (ICDs). Adverse effects of antiarrhythmic drugs on ICD function and adverse interactions between ICDs and pacemakers have been documented. The effect of antiarrhythmic drugs on the defibrillation threshold (DFT) in patients has not been well assessed. Most studies have been performed in animal models in which cardiac function was normal and drug doses were supraphysiologic. In addition, most studies have utilized monophasic defibrillation shock waveforms and epicardial lead systems. Despite the lack of clinical data applicable to current defibrillation systems, it appears that chronic amiodarone administration causes a significant DFT increase. In addition, antiarrhythmic drugs can influence antitachycardia pacing and tachycardia sensing. Defibrillation shocks can cause transient failure of pacemaker sensing and pacing, and cause spurious pacemaker reprogramming. Pacemaker function can result in ICD oversensing, leading to inappropriate therapy, or cause ICD undersensing, potentially resulting in failure to deliver therapy during ventricular fibrillation. The susceptibility of an ICD to undersensing appears related to the amplitude of the pacing stimulus artifact recorded by the ICD rate-sensing circuit and to the characteristics of the fibrillation electrogram. Preliminary data suggest that undersensing of ventricular fibrillation by current ICDs is an unlikely event.

Anti-Arrhythmia Agents↗
PubMed1996

Conduction block in the inferior vena caval-tricuspid valve isthmus: association with outcome of radiofrequency ablation of type I atrial flutter.

OBJECTIVES: We sought to 1) correlate conduction block in the isthmus of the right atrium between the inferior vena cava and the tricuspid annulus with the efficacy of catheter ablation of type I atrial flutter, and 2) characterize the effects of ablative lesions on the properties of isthmus conduction. BACKGROUND: There are few data on the mechanism of persistent suppression of recurrence of atrial flutter by catheter ablation. METHODS: Thirty-five patients with type I atrial flutter underwent catheter mapping and ablation. Radiofrequency lesions were applied in the isthmus. Transisthmus conduction before and after the lesions was assessed during atrial pacing in sinus rhythm from the medial and lateral margins of the isthmus at cycle lengths of 600, 400 and 300 ms and the native flutter cycle length. Isthmus conduction block was defined using multipolar recording techniques. There were three treatment groups: group 1 = radiofrequency energy applied during flutter, until termination (n = 14); group 2 = radiofrequency energy applied during atrial pacing in sinus rhythm from the proximal coronary sinus at a cycle length of 600 ms, until isthmus conduction block was observed (n = 14); and group 3 = radiofrequency energy applied until an initial flutter termination, after which further energy was applied during atrial pacing in sinus rhythm until isthmus conduction block was observed (n = 7). RESULTS: In group 1, after the initial flutter termination, isthmus conduction block was observed in 9 of the 14 patients. In each of these nine patients, flutter could not be reinitiated. In each of the remaining five patients, after the initial flutter termination, isthmus conduction was intact and atrial flutter could be reinitiated. Ultimately, successful ablation in each of these patients was also associated with isthmus conduction block. In groups 2 and 3, isthmus conduction block was achieved during radiofrequency energy application, and flutter could not subsequently be reinitiated. Before achieving conduction block, marked conduction slowing or intermittent block, or both, was observed in some patients. In some patients, isthmus conduction block was pacing rate dependent. In addition, recovery from conduction block was common in the laboratory and had a variable time course. At a mean follow-up interval of 10 months (range 1 to 21), the actuarial incidence of freedom from type I flutter was 80% (recurrence in three patients at 7 to 15 months). CONCLUSIONS: Isthmus conduction block is associated with flutter ablation success. Conduction slowing or intermittent block, or both, in the isthmus can occur before achieving persistent block. Recovery of conduction after achieving block is common. Follow-up has revealed a low rate of flutter recurrence after achieving isthmus conduction block, whether the block was achieved in conjunction with termination of flutter.

Adult↗
PubMed1996

Multicenter comparison of truncated biphasic shocks and standard damped sine wave monophasic shocks for transthoracic ventricular defibrillation. Transthoracic Investigators.

BACKGROUND: The most important factor for improving out-of-hospital ventricular fibrillation survival rates is early defibrillation. This can be achieved if small, lightweight, inexpensive automatic external defibrillators are widely disseminated. Because automatic external defibrillator size and cost are directly affected by defibrillation waveform shape and because of the favorable experience with truncated biphasic waveforms in implantable cardioverter-defibrillators, we compared the efficacy of a truncated biphasic waveform with that of a standard damped sine monophasic waveform for transthoracic defibrillation. METHODS AND RESULTS: The principal goal of this multicenter, prospective, randomized, blinded study was to compare the first-shock transthoracic defibrillation efficacy of a 130-J truncated biphasic waveform with that of a standard 200-J monophasic damped sine wave pulse using anterior thoracic pads in the course of implantable cardioverter-defibrillator testing. Pad-pad ECGs were also examined after transthoracic defibrillation. After the elimination of data for 24 patients who did not meet all protocol criteria, the results from 294 patients were analyzed. The 130-J truncated biphasic pulse and the 200-J damped sine wave monophasic pulse resulted in first-shock efficacy rates of 86% and 86%, respectively (P = .97). ST-segment levels measured 10 seconds after the shock in 151 patients in sinus rhythm were -0.26 +/- 1.58 and -1.86 +/- 1.93 mm for the 130- and 200-J shocks, respectively (P < .0001). CONCLUSIONS: We found that 130-J biphasic truncated transthoracic shocks defibrillate as well as the 200-J monophasic damped sine wave shocks that are traditionally used in standard transthoracic defibrillators and result in fewer ECG abnormalities after the shock.

Adolescent↗
PubMed1996

The results of atrial flutter ablation in patients with and without a history of atrial fibrillation.

To determine the impact of atrial flutter radiofrequency catheter ablation on recurrence of atrial flutter and atrial fibrillation, 32 patients with atrial flutter (18 with a history of atrial fibrillation) were followed for a mean of 8.6 months; atrial flutter has not recurred after 1 (26 patients) or 2 (5 patients) successful ablation procedures. Atrial flutter did not appear proarrhythmic for atrial fibrillation, with only 1 of 15 patients without a history of atrial fibrillation developing the arrythmia in the absence of an alcohol binge or cocaine use.

Atrial Fibrillation↗
PubMed1996

Factors associated with successful implantation of nonthoracotomy defibrillation lead systems.

Two hundred forty-three consecutive patients underwent attempted implantation of nonthoracotomy defibrillation lead (NTL) systems. The importance of clinical and lead-related factors were analyzed regarding their relation with implantation failure caused by an unacceptably high defibrillation threshold (DFT). Overall, 33 (14%) of 243 patients failed NTL implantation. Patients undergoing attempted implantation of NTL systems with monophasic shock waveforms (monophasic group, n = 145) had an incidence of failed implantation of 22% (n = 32) versus an incidence of 1% (n = 1) among patients undergoing attempted implantation by using biphasic shock waveforms (biphasic group, n = 98; odds ratio, 26.9; p < 0.001). The incidence of success and simplicity of implantation of NTL systems was markedly improved in patients undergoing NTL implantation by using biphasic shock waveforms. Clinical factors could be used to stratify patients in the monophasic group for their risk of implantation failure. In the biphasic group, no clinical factor could be correlated with a low DFT with a fully endovascular system.

Aged↗
PubMed1996

Idiopathic right ventricular outflow tract tachycardia: narrowing the anatomic location for successful ablation.

Pace mapping used to locate the site for ablation of idiopathic right ventricular outflow tract (RVOT) ventricular tachycardia remains difficult and time-consuming. A method to facilitate pace mapping and the most common site of ablation of this tachycardia are reported. In 18 consecutive patients with RVOT ventricular tachycardia, electrocardiographic criteria based on the QRS orientation in lead 1 and the R wave progression in the precordial leads were used to find pace maps matching the arrhythmia. Identical pace maps were obtained on the septum of the RVOT in 16 patients and resulted in successful ablations. These sites were concentrated in the anterior superior aspect of the RVOT determined by fluoroscopic imaging. In the remaining two cases identical pace maps could not be found in this area. The results of this study narrow the anatomic location for radiofrequency ablation of idiopathic RVOT ventricular tachycardia. This is the first description of an electrocardiography-guided approach to finding an identical pace map in the RVOT.

Adult↗
PubMed1996

Effect of bundle branch block on local electrogram morphologic features: implications for arrhythmia diagnosis by stored electrogram analysis.

Analysis of stored local ventricular electrogram recordings is a useful diagnostic tool in the evaluation of patients with implantable cardioverter defibrillators. Visual analysis of local electrogram morphologic features has been demonstrated to be useful in distinguishing ventricular tachycardia from supraventricular rhythm. The effect of bundle branch block (BBB) aberration during supraventricular tachycardia on local electrogram morphologic features is not entirely clear. Erroneous diagnoses resulting from a change in electrogram morphologic features with BBB may occur. To determine whether the development of BBB can produce a change in local electrogram morphologic features and whether this change is dependent on the site of recording, we retrospectively reviewed local electrogram recordings from 23 patients who had intermittent BBB during electrophysiologic evaluation of documented or suspected supraventricular tachycardia. Local electrogram recordings from catheters placed in the right ventricular apex and coronary sinus during supraventricular tachycardia with BBB aberrancy were compared with recordings during narrow complex supraventricular tachycardia or normal sinus rhythm. Bipolar recordings were made with a 5 mm interelectrode distance with filter settings at 40 to 400 Hz. Three independent blinded observers defined the paired electrograms as the same or distinctly different. During right BBB a change in electrogram morphologic features was demonstrated in 11 (85%) of 13 recordings from the right ventricular apex and in only 1 (8%) of 12 recordings from the coronary sinus. In contrast, during left BBB a change in electrogram morphologic features was seen in 6 (100%) of 6 recordings from the coronary sinus and in only 1 (8%) of 13 recordings from the right ventricular apex. These results demonstrate that when the described recording techniques are used, a change in local ventricular electrogram morphologic features BBB is predominantly manifest in recording sites ipsilateral to the BBB, whereas recording sites contralateral to the BBB are relatively unaffected. This information may have implications regarding interpretation of stored electrograms when an attempt is made to establish a rhythm diagnosis leading to implantable cardioverter defibrillator therapy.

Adolescent↗
PubMed1996

Radiofrequency catheter ablation of atrial tachycardia with unusual left atrial sites of origin: report of two cases.

Two cases of successful radiofrequency catheter ablation of adult-onset atrial tachycardia originating from the left atrium adjacent to the mitral annulus are presented. Endocardial catheter activation mapping performed by retrograde or atrial transseptal approach revealed presystolic activation at the successful ablation site in both patients, and fractionation during sinus rhythm and tachycardia in one. The 12-lead electrocardiographic P wave appearance was suggestive of a left atrial tachycardia origin in both cases.

Catheter Ablation↗
PubMed1996

Bundle branch reentry ventricular tachycardia: an investigation of the circuit with resetting.

We describe a patient with bundle branch reentry ventricular tachycardia with 1:1 VA conduction in whom resetting was performed while obtaining simultaneous recordings from the right ventricular apex (V) and His-bundle electrogram. Both the tachycardia return cycle and the V-His interval demonstrated an increasing reset response, while the His-V interval demonstrated a flat reset response. These reset responses are consistent with a partially excitable gap localizing to the V-His portion of the bundle branch reentry circuit.

Adult↗
PubMed1996

Effects of high and low shock energies on sinus electrograms recorded via integrated and true bipolar nonthoracotomy lead systems.

INTRODUCTION: The purpose of this investigation was to prospectively evaluate the voltage- and time-dependent characteristics of a biphasic defibrillator discharge on the amplitude of the rate sensing electrogram recorded from two "integrated" and one true bipolar nonthoracotomy lead system. Prolongation of redetection time has been noted after a failed first shock with nonthoracotomy lead systems. However, a prospective evaluation of the time- and voltage-dependent effects of biphasic shocks on electrogram amplitude with clinically utilized lead systems has not been systematically performed. METHODS AND RESULTS: Five- then 30-J R wave synchronous biphasic discharges were delivered during the supraventricular rhythm through three nonthoracotomy lead systems (Medtronic Transvene, Ventritex TVL, and CPI Endotak C 60 Series). The R wave amplitude was measured immediately postshock and for up to 1 minute. Amplitude changes were compared with preshock baseline value. A 5-J discharge had minimal effect on the R wave amplitude recorded from the three lead systems; however, 30 J resulted in significant diminution in R wave amplitude recorded from the integrated bipolar leads (in the Endotak lead to a greater extent than the TVL lead) with minimal effects on the Transvene lead. Following a 30-J discharge, the time constant for R wave recovery was 4.2, 14.9, and 15.3 seconds for Transvene, TVL, and Endotak 60 leads, respectively. CONCLUSION: There are voltage- and time-dependent reductions in postshock R wave amplitude. Integrated bipolar systems appear more affected than the "true" bipolar lead evaluated. This may be due, in part, to lead design, distance of distal defibrillating surface from rate sensing cathode, and the incorporation of the defibrillating surface as the rate sensing anode. The influence of post-shock R wave diminution on subsequent redetection remains speculative but may have implications for subsequent lead development.

Adult↗
PubMed1996

Early postoperative rise in defibrillation threshold in patients with nonthoracotomy defibrillation lead systems: attenuation with biphasic shock waveforms.

INTRODUCTION: In patients with non-thoracotomy defibrillation lead (NTL) systems coupled with monophasic shock waveforms, the defibrillation threshold (DFT) rises early after implantation. There is little information regarding features predictive of the DFT rise, or DFT changes early after implantation of NTL systems coupled with biphasic shock waveforms. METHODS AND RESULTS: DFT measurements were performed serially at implantation, prior to hospital discharge (mean 4 +/- 3 days), and at follow-up (mean 49 +/- 22 days) in 146 patients with an NTL system. Factors were assessed for association with a "clinically important" early postimplantation DFT rise, defined as a rise of > or = 2 energy steps (2 to 4 J per step; > or = 5 J total). A clinically important early postimplantation DFT rise occurred in 48 patients (33%). Univariate predictors of the rise included the monophasic shock waveform, the Medtronic Transvene lead system, the presence of a subcutaneous defibrillation patch, and the number of shocks delivered during the implantation procedure. However, the only independent predictor of a clinically important DFT rise was the monophasic shock waveform (F = 18, P < 0.001). For the monophasic patient group (n = 79), the incidence of a DFT rise was 53% (n = 42). For the biphasic patient group (n = 67), the incidence of a DFT rise was 9% (n = 6). The clinical characteristics of the monophasic and biphasic groups were not significantly different, nor were their DFTs at implantation. Among a subgroup of 18 consecutive patients who underwent serial DFT testing utilizing both monophasic and biphasic waveforms, the incidence of a clinically important DFT rise with monophasic (n = 9,50%) was higher than with biphasic shocks (n = 3,17%; P = 0.05). CONCLUSION: NTL systems coupled with biphasic shock waveforms have an attenuated incidence of a clinically important DFT rise early after implantation, relative to patients with NTL systems coupled to monophasic waveforms.

Analysis of Variance↗