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Biomedical subjects

F I Marcus

Publications and source records attributed to F I Marcus.

At least 37 records · Page 2Linked to original sources
PubMed1996

Patency of infarct-related artery. Effect of restoration of anterograde flow on vagal reflexes. ATRAMI (Automatic Tone and Reflexes After Myocardial Infarction) Investigators.

BACKGROUND: In post-myocardial infarction (MI) patients, the restoration of anterograde flow in the infarct-related artery (IRA) significantly improves survival. Limitation of infarct size and increased electrical stability of the myocardium are likely operating mechanisms for this beneficial effect. We tested the hypothesis that patency of the IRA may enhance vagal reflexes, a factor known to affect electrical stability of the infarcted myocardium. METHODS AND RESULTS: Analysis of angiographic data was performed in 359 of 1284 post-MI patients enrolled in a multicenter prospective study within 8 weeks after the index MI. All the patients underwent baroreflex sensitivity (BRS) assessment by the phenylephrine method. The BRS of the entire population averaged 8.2+/-5.5 ms/mm Hg and was significantly related to age but not to ejection fraction (EF). One-, two-, and three-vessel disease was present in 138, 96, and 99 patients, respectively, while no coronary stenosis was observed in 26. IRA patency was documented in 234 patients (65%), while in the remaining 125 (35%), the artery remained occluded. Patients with occluded IRAs had more extensive coronary disease (2 to 3 vessels, 71% versus 46%, P<.01) and more depressed left ventricular (LV) function (LVEF, 48+/-13% versus 53+/-12%, P<.001). Patency of the IRA was associated with higher BRS values (BRS, 8.9+/-5.8 versus 7.1+/-4.7 ms/mm Hg, P<.005) and with a lower incidence (9% versus 18% P<.02) of markedly depressed BRS (<3 ms/mm Hg), a condition suggested by preliminary studies to be associated with an increased risk of post-MI mortality. The association between IRA patency and BRS was more evident in anterior than in inferior MI. Multivariate regression analysis showed that age of the patient and patency of the IRA were the major independent determinants of BRS, while LVEF was weakly related to BRS and only when analyzed as a categorized variable. CONCLUSIONS: The presence of an open IRA is associated with higher baroreflex sensitivity, and this effect is largely independent of limitation of infarct size by IRA patency. These data offer new insights into the mechanisms by which coronary artery patency may affect cardiac electrical stability and survival.

Adult↗
PubMed1996

Simultaneous multipolar radiofrequency ablation in the monopolar mode increases lesion size.

Delivery of radiofrequency (RF) energy from the distal tip of electrophysiology catheters produces lesions that may be too small to ablate arrhythmogenic sites during a single application of RF energy. To produce larger lesions, we delivered RF energy via a quadripolar catheter in which all four electrodes were connected in unipolar fashion. The catheter (Webster Labs) had a 4-mm tip, 2-mm ring electrodes, and 2-mm interelectrode distance. Lesion size was compared using RF energy delivered in a multipolar configuration with that delivered only to the distal tip using fresh bovine ventricular tissue. In vivo, RF lesions were made in dogs using the distal tip as well as all four poles of the same catheter inserted percutaneously. RF energy was delivered using a constant voltage at a frequency of 400 kHz. Preliminary experiments were conducted to determine the maximum power deliverable without coagulation using each electrode configuration. The use of simultaneous multipolar RF ablation produced significantly larger lesions both in vitro and in vivo. The length of the lesion was increased by a factor of approximately 2 in both the in vitro and in vivo experiments. There was a trend toward an increasing depth of the lesion by simultaneously applying RF energy to all four electrodes. Lesion width was significantly increased in the in vivo studies. We concluded that simultaneous multipolar delivery of RF energy produces larger lesions than can be obtained with delivery of RF energy to the distal tip alone. This technique may offer a means of increasing lesion size, leading to a decrease in the number of applications of RF energy necessary for ablation of arrhythmias.

Animals↗
PubMed1996

Comparison of gold versus platinum electrodes on myocardial lesion size using radiofrequency energy.

During radiofrequency (RF) catheter ablation of arrhythmias, temperatures that approach 100 degrees C cause a coagulum to form on the ablation electrode that results in an increase in electrical impedance and prevents further energy delivery. Since gold has nearly four times the thermal conductivity as platinum, the metal commonly used, it was postulated that gold tip electrodes could deliver more power and produce deeper lesions because of its greater heat dissipation from the electrode-tissue interface to the circulating blood. To test this hypothesis, RF energy was applied to fresh bovine ventricular myocardium using 6 French catheters with 2-mm long distal electrodes made from gold or platinum. Similar studies were also conducted using 7 French catheters with 4-mm long distal electrodes. Maximum lesion depth was defined as that produced with the level of energy just below that causing an impedance rise. A maximum lesion depth of 6.2 +/- 0.7 mm (mean +/- SD) was obtained with the gold 2-mm electrode and 4.7 +/- 0.5 mm with the platinum electrode (P = 0.003). The 4-mm gold electrode produced a maximum lesion depth of 7.2 +/- 1.4 mm, while a catheter with a 4-mm platinum electrode caused a maximum lesion depth of 5.8 +/- 0.7 mm (P = 0.05). We conclude that deeper lesions should be able to be made when RF energy is delivered to a gold rather than platinum tip electrode.

Animals↗
PubMed1996

Diagnostic clues from the surface ECG to identify idiopathic (fascicular) ventricular tachycardia: correlation with electrophysiologic findings.

INTRODUCTION: An RS interval > 100 msec in precordial leads has been recently described for the diagnosis of ventricular tachycardia (VT). The aim of this study was to assess the value of this criterion when applied to patients with right bundle branch block pattern, left-axis deviation (fascicular) VT sensitive to verapamil. METHODS AND RESULTS: Eleven patients (mean age 31 +/- 11 years; range 16 to 51) had a mean heart rate of 164 +/- 37 beats/min (range 107 to 230) during VT. The QRS complex axis was -92 degrees +/- -15 degrees (range -80 to -115). The mean QRS duration was 121 +/- 9 msec (range 105 to 140). The mean RS interval was 67 +/- 9 msec (range 60 to 80). Fusion beats were present in 2 patients (18%), and AV dissociation confirmed by electrophysiologic study was found on ECG in 8 (73%) of 11. During tachycardia, the QRS-H' interval was 19 +/- 10 msec (range 10 to 30) in 6 of 11 patients. In seven patients, a fast, unique (or double) presystolic potential lasting 32 msec (range 12 to 40) occurring before the onset of the QRS complex was found at the site of origin of VT, localized in the inferior apical left ventricular septum. In all cases, VT was successfully treated by catheter ablation. CONCLUSION: A wide QRS complex tachycardia with right bundle branch block and left-axis deviation sensitive to verapamil observed in a young patient without structural heart disease should not be confused with supraventricular tachycardia with aberrancy but rather suggests the presence of fascicular VT. As opposed to VT associated with structural heart disease, the RS interval is < 80 msec in all precordial leads in all cases. Independent of this parameter, AV dissociation detectable on surface ECG has a sensitivity of 73%, which increases to 82% in the presence of fusion beats.

Adolescent↗
PubMed1996

Radiofrequency catheter ablation of common atrial flutter in 200 patients.

INTRODUCTION: The purpose of this study was to evaluate the efficacy and safety of radiofrequency (RF) catheter ablation of common atrial flutter and to determine the optimum target sites in a large series of patients. Three different approaches were used to target the ablation site. The first used a combined anatomic and electrophysiologic approach, whereas the second and the third approaches relied primarily on anatomic guidelines to target the critical area in the atrial flutter reentrant circuit located in the low right atrium. BACKGROUND: Recent studies report the efficacy of RF current application in the low right atrial region to interrupt and prevent recurrences of common atrial flutter using either anatomic or electrophysiologic targets. However, larger groups of patients are required to confirm the efficacy of this technique and to specify the target sites. METHODS AND RESULTS: Two hundred consecutive patients with drug-resistant common atrial flutter were studied. In the first 50 patients, target sites were localized using both anatomic landmarks and electrophysiologic parameters. The anatomic landmarks were area 1 between the tricuspid valve and inferior vena cava orifice; area 2 between the tricuspid valve and coronary sinus ostium; and area 3 between the inferior vena and coronary sinus. The electrophysiologic criterion was to ablate when there was an atrial electrogram occurring during the plateau phase (preceding F wave). The first targeted area was that giving the more stable catheter position. In the following 30 patients, we assessed the effect of RF energy application in a single line to area 1 in the first 10 patients, area 2 in the next 10, and area 3 in the last 10 patients. In the last 120 patients, RF energy was applied only in area 1 using repeated applications. RF energy of 12 to 30 W, or that achieving a temperature of 70 degrees C, was applied for 60 to 90 seconds at each site. The endpoint of the ablation procedure was interruption and noninducibility of common atrial flutter in the first 110 patients and additional isthmal block in 48 of the last 90 patients. Overall, atrial flutter was interrupted and rendered noninducible after a single session in 191 (95%) patients and could not be interrupted in 9 (4.5%) patients. The mean number of RF applications was 12 +/- 8. After a mean follow-up of 24 +/- 9 months, recurrences occurred in 31 (15.5%) patients, 26 of whom underwent a successful second or third session without further recurrences of atrial flutter. Atrial fibrillation not documented before the ablation was detected in 11 patients. On a retrospective analysis of the final successful site in the first group of 50 patients, the location was in area 1 in 39% of patients; area 2 in 36% of patients, and area 3 in 25% of patients. Atrial electrograms recorded at these sites showed a single spike pattern in 46% of patients, and double spike pattern (28%) or fractioned electrogram in 26% patients. When lines of RF lesions were placed at several sites, they produced a success rate of 70%, 40%, and 10% at areas 1, 2, and 3 respectively. In the last series of 120 patients, the procedure was successful in 119 patients: 92% of whom were successfully treated only by a linear lesion between the tricuspid annulus isthmus and the inferior vena cava, and the other 8% by additional applications near the coronary sinus ostium. No complications were observed. CONCLUSIONS: RF catheter ablation of atrial flutter can be done with a high success rate and is safe. The highest success rate is achieved with RF energy applied in the isthmus between the inferior vena cava orifice and the tricuspid valve. However, 15.5% of patients need multiple sessions to achieve success because of recurrence of flutter. Further follow-up is needed to evaluate the long-term effects of this procedure.

Adult↗
PubMed1996

Titrating cardiovascular drugs.

Titrating cardiovascular drugs is important to ensure efficacy and to minimize the risk of toxicity. A serum assay is extremely useful to guide digoxin therapy. Assessment of the effect of warfarin on blood clotting should be used to adjust dose. Serum cholesterol and lipid measurements guide therapy with antilipemic agents. The antihypertensive drugs, beta blockers, calcium channel blockers, and vasodilators can be assessed by their clinical effects. There is no strict relation between serum concentration of antiarrhythmic drugs and their effects, nor is it clear that the long-term efficacy of these drugs can be assessed by surrogate end points.

Anticoagulants↗
PubMed1995

Accelerometer systolic time intervals as fast-response sensors of upright posture in the young.

BACKGROUND: Sensors of posture may improve rate-adaptive pacing in syndromes where syncope occurs in the upright posture, particularly in the young. No sensor of posture has been described to date. Previous studies suggest that two sensors currently under investigation (preejection period [PEP] and left ventricular ejection time [LVET] systolic time intervals [STIs] and accelerometers) may be affected by posture. A PEP-sensing pacemaker is available commercially in which heart rate (HR) decreases with an increase in PEP (delta(HR)/delta[PEP]< 0). In patients with upright syncope, it is not known how such algorithms respond to posture. Also, it is not known whether STIs correlate with posture independent of autonomic tone. METHODS AND RESULTS: We studied accelerometer-derived STIs in head-upright tilt-testing with beta-blockade and catecholamine stimulation in patients with syncope or presyncope using an ultra-low-frequency accelerometer placed on the chest. Thirty-two patients age 6 to 22 years with unexplained recurrent syncope or presyncope underwent tilt-testing involving two to four tilts (60 degrees) at baseline, during esmolol infusion (500 micrograms/kg load, 50 to 140 micrograms/kg per minute), after esmolol withdrawal, and during isoproterenol infusion if not contraindicated. PEP, LVET, and other indexes were quantified, and their relations to posture and to autonomic state were determined. With tilt, PEP increased from 98.9 +/- 2.2 to 109.1 +/- 2.8 msec (P < .0001), and LVET decreased (supine-to-upright) from 295.5 +/- 4.5 to 247.2 +/- 4.7 msec (P < .0001). PEP/LVET changed from 0.337 +/- 0.01 to 0.45 +/- 0.02 (P < .0001). Similar postural changes were observed during tilt with beta-blockade and esmolol withdrawal, and during isoproterenol infusion. STI changes occurred immediately on postural change and were stable. Postural change of PEP was greater than the beta-adrenergic effect by 6:1. Postural change of STIs was independent of vagal tone. CONCLUSIONS: First, accelerometer-derived STIs detect postural changes. Because these changes are independent of autonomic tone and are rapid and stable, they may be useful as fast-response sensors of upright posture in rate-adaptive pacemakers. Second, with postural change, HR increases when PEP increases. However, PEP-sensing pacemakers presently under investigation assume the opposite (inverse) mathematical relationship. Therefore, current PEP-sensing pacemakers use an incorrect algorithm for physiological postural responses in syncope patients. These data predict a paradoxical tachycardic response to the supine posture in patients implanted with these devices.

Adolescent↗
PubMed1995

Cost of initial therapy in the Electrophysiological Study Versus ECG Monitoring trial (ESVEM).

BACKGROUND: Patients randomized to either serial electrophysiological testing (EPS) or serial Holter monitoring (HM) to guide antiarrhythmic therapy for life-threatening ventricular arrhythmias had equivalent rates of mortality and arrhythmia recurrence in the ESVEM study. This report analyzes the effects of EPS, HM, and clinical factors on the charges for initial evaluation and management of patients with life-threatening ventricular arrhythmias. METHODS AND RESULTS: Ten of 14 clinical centers participating in ESVEM provided bills from the initial hospitalization for randomized patients. Predictors of charges (1991 dollars) were analyzed by linear regression after logarithmic transformation. Initial hospital charge data were obtained for 286 patients randomized in ESVEM (88% of patients eligible for this substudy, 59% of all ESVEM patients). Patients with charge data were somewhat more likely to be older, to be female, and to have failed previous antiarrhythmic drug therapy at study entry and were less likely to have a drug predicted effective after randomization. Mean overall hospital charges were $35,986 (SD, $32,628) with a median of $24,532 (interquartile range, $16,126 to $43,593). Prerandomization patient characteristics generally had insignificant effects on charges, with the exception of presentation with resuscitated sudden death (28% increase in charges, P = .01) and heart failure (26% increase in charges, P = .02). Patients randomized to EPS had higher mean charges for evaluation ($42,002 versus $29,970, P = .0015) as well as more drug trials (3.0 versus 2.1, P = .0001) and a longer hospital stay (19.6 versus 13.9 days, P = .0007). In a multivariate regression model, failure to find an effective drug (P = .0001), the number of drug trials (P = .0001), and resuscitated sudden death as the presenting arrhythmia (P = .0001) were the only independent predictors of higher initial charges. CONCLUSIONS: (1) Initial hospital charges are significantly higher for EPS-guided than HM-guided therapy. (2) The higher charges for EPS-guided therapy were due to a greater number of drug trials and a lower probability of finding an effective drug. (3) Failure to find an effective drug, a larger number of drug trials, and a history of resuscitated sudden death independently predict higher charges.

Aged↗
PubMed1995

Radiofrequency catheter ablation of common atrial flutter in 80 patients.

OBJECTIVES: The purpose of this study was to evaluate the efficacy and safety of radiofrequency catheter ablation of common atrial flutter and to determine the optimal target sites in a large series of patients. BACKGROUND: Recent studies report the efficacy of radiofrequency current application in the low right atrial region to interrupt and prevent recurrences of common atrial flutter. However, larger groups of patients are required to confirm the efficacy of this technique and to specify the target sites. METHODS: Two different approaches were used to target the ablation site in 80 consecutive patients. In the first 50 patients, target sites were localized using both anatomic landmarks and electrophysiologic variables. Three anatomic landmarks were used: area 1 = between the tricuspid valve and inferior vena cava orifice; area 2 = between the tricuspid valve and coronary sinus ostium; area 3 = between the inferior vena cava and coronary sinus. The electrophysiologic criterion was to ablate when there was a stable atrial electrogram during the plateau phase. In the next 30 patients we assessed the effect of application of radiofrequency energy in a single line in area 1, 2 or 3 in groups of 10 patients. RESULTS: Overall atrial flutter was interrupted and rendered noninducible after a single session in 72 patients (90%) and could not be interrupted in 8 (10%). The mean (+/- SD) number of radiofrequency applications was 12 +/- 8. After a mean (+/- SD) follow-up of 20 +/- 8 months, recurrences occurred in 14 patients (17%). The location of the final successful site in the first group of 50 patients was in area 1 in 39%, area 2 in 36% and area 3 in 25%. In the next 30 patients, when lines of radiofrequency lesions were placed at several sites, they produced success rates of 70%, 40% and 10% at areas 1, 2 and 3, respectively. CONCLUSIONS: Radiofrequency catheter ablation of atrial flutter can be performed with a high success rate and is safe. The highest success rate is achieved with radiofrequency energy applied in the isthmus between the inferior vena cava orifice and tricuspid valve.

Actuarial Analysis↗
PubMed1995

Application of ultrasound energy for intracardiac ablation of arrhythmias.

Ultrasound is a potential energy source for cardiac ablation. Small ultrasound applicators were tested for their ability to create lesions in cardiac tissue. Ultrasound applicators were designed, constructed and tested in canine cardiac tissue in degassed normal saline, and both in vitro and in vivo, lesions were produced by using transducers with frequencies of about 10 MHz. Lesion depth increased with longer duration of energy delivery from 15-60 s, and there was a linear relationship between increasing power and depth of lesions. Seven in vivo experiments in open-chest dogs were performed, and the ultrasound transducers were mounted on the tip of 7-French angiographic catheters. On the epicardium the maximum lesion depth was 9 mm. When the transducer was inserted into the left ventricle, lesions of 8.7 +/- 2.9 mm (n = 4) were produced. It is concluded that an ultrasound transducer mounted on a cardiac catheter can produce lesions that may be useful for ablation of cardiac arrhythmias.

Adult↗
PubMed1995

Arrhythmogenic right ventricular dysplasia/cardiomyopathy: a review.

Right ventricular dysplasia is being recognized with increasing frequency. It should be considered as a cause of ventricular tachycardia of left bundle branch block configuration and/or sudden unexpected death particularly during exercise in young men. The electrocardiogram (ECG) may show anterior precordial T wave inversion, particularly in lead V2 and/or a QRS complex duration > or = 110 ms in the right precordial leads. Echocardiographic studies focusing on the size and wall-motion abnormalities of the right ventricle are useful in confirming the diagnosis. Radionuclide angiography usually shows a moderately or markedly depressed right ventricular ejection fraction with normal or relatively well preserved left ventricular function. Cinemagnetic resonance imaging demonstrates abnormal fatty infiltration of the right ventricular myocardium and can show increased right ventricular dimensions as well as wall-motion abnormalities. Contrast ventricular angiography remains the gold standard to establish the diagnosis but must be performed with appropriate views and with care to avoid ventricular premature beats. Quantitative analysis of right ventricular dimensions can be performed in selected centers. Three-dimensional echocardiography is a promising approach to evaluate right ventricular wall-motion abnormalities as well as to demonstrate enlargement. The etiology and pathogenesis of this condition is not clear. A familial incidence has been well-documented in certain areas and an abnormal gene has been identified. Sporadic cases are the most common. In contrast to Uhl's anomaly, characterized pathologically by areas of paper thin myocardium, the right ventricular free wall is minimally decreased in thickness. Histologically there appears to be a replacement of musculature by fatty tissue. Medical therapy with sotalol or amiodarone, or combination therapy (Class Ic drugs plus beta-blocking drugs, or amiodarone plus beta-blocking drugs) is frequently effective in preventing recurrent ventricular tachycardia. Ablation using radiofrequency (RF) or direct current (DC) energy is reserved for patients who are unresponsive or intolerant of antiarrhythmic drugs. Ventricular arrhythmia recurrence of different morphology is not uncommon after apparent successful ablation. There appears to be a lower rate of successful ablation using RF energy. However, patients with this condition who have been resuscitated from sudden cardiac death or those refractory to medical treatment are candidates for ablation, implantation of an automatic cardioverter defibrillator, or cardiac transplantation. Surgery consisting of total disconnection of the right ventricle is a promising therapeutic modality.

Adult↗
PubMed1994

Effects of non-right-handedness on risk for sudden death associated with coronary artery disease.

The hypothesis that non-right-handedness is associated with sudden cardiac death was tested based on evidence that sympathetic imbalance may contribute to ventricular arrhythmogenesis and evidence that left-handers may have a shorter lifespan than right-handers. The study included 26 patients with coronary artery disease (CAD), a history of ventricular tachycardia-ventricular fibrillation (VT-VF), and implanted defibrillators, and 26 patients with CAD and no history of serious arrhythmias who were matched for age, sex, and New York Heart Association functional class. Patients with any history of neurologic disorders were excluded. Left-handers either wrote with the left hand or were converted from left- to right-handedness in childhood. Non-right-handers used the left hand for writing, drawing, or throwing. Handedness rates in patients with VT-VF and case-control subjects were compared with published norms in the general population to take expected rates into account. The rates of left-handedness (6 of 26 or 23.1%) and non-right-handedness (9 of 26 or 34.6%) in patients with VT-VF were significantly higher (p < 0.003 and p < 0.0001, 2-tailed, respectively) than those of similarly aged adults in the general population (left-handedness, 5%; non-right-handedness, 10.2%). The rates of left-handedness (2 of 26 or 7.7%) and non-right-handedness (4 of 26 or 15.4%) observed in the case-control group correspond closely to the expected values for that group (left-handedness, 1.3 of 26 or 5%; non-right-handedness, 2.65 of 26 or 10.2%) derived from the general population rates and were not significantly different from them.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1994

Correlation of signal-averaged P wave with electrophysiological testing for atrial vulnerability in strokes of unexplained etiology.

UNLABELLED: Atrial fibrillation is considered the main cause of cardioembolic strokes. After detailed investigations, about 30% of ischemic strokes remain unexplained. A percentage of these ischemic attacks may result from asymptomatic episodes of paroxysmal atrial fibrillation (PAF). Previous studies have demonstrated that electrophysiological testing and signal-averaged P wave (SAPW) ECG are useful to detect patients with PAF. METHODS AND RESULTS: Twenty patients with unexplained ischemic strokes had electrophysiological studies (EPS) to determine atrial vulnerability and SAPW recordings. At EPS, patients were classified in group I (10 patients) if they had a latent atrial vulnerability index < 2 and/or more than 1 minute of sustained atrial arrhythmia. Otherwise they were classified in group II (10 patients). In group I, the filtered P wave duration was greater: 142 versus 120 msec (P = 0.03) and RMS 30 tended to be lower: 2.54 versus 4.13 microV (P = 0.11) than in group II. A filtered P wave duration > 125 msec associated with a RMS 30 < 3 microV had a positive predictive value of 78% and a negative predictive value of 88% for the detection of patients with abnormal atrial vulnerability at EPS. CONCLUSIONS: SAPW may be useful to identify patients at risk of PAF who may be candidates for EPS.

Atrial Fibrillation↗
PubMed1994

Involvement of a nodofascicular connection in supraventricular tachycardia with VA dissociation.

We present the case of a patient with episodes of supraventricular tachycardia and atrial dissociation that were terminated by either adenosine or verapamil. Involvement of an accessory pathway was shown by ventricular extrastimuli, elicited during His-bundle refractoriness, that interrupted the tachycardia or advanced the next His potential. The tachycardia circuit was demonstrated to be confined to the nodofascicular region based on the exclusion of surrounding tissues. Atrial activity, including that in the perinodal region, was totally dissociated during tachycardia. The lowest part of the circuit was determined to be located above the Hisian bifurcation, as multiple episodes with either a right or left bundle branch configuration during tachycardia did not modify the HH cycle. The ventricular septum summit was determined not to be involved, as no preexcitation was present during tachycardia or atrial pacing, and the right bundle branch was not part of the circuit. Radiofrequency current applied beneath the tricuspid valve at the His region successfully eliminated the nodofascicular connection with preservation of 1:1 AV conduction. The anatomical substrate underlying the abnormal connection may be either nodofasciculoventricular Mahaim fibers or a duality or dispersion of the nodo-Hisian conducting system.

Adult↗
PubMed1994

Successful catheter ablation of atrial fibrillation.

INTRODUCTION: Catheter ablation of a case of incessant atrial fibrillation was attempted using linear right atrial lesions created by sequential applications of radiofrequency energy. METHODS AND RESULTS: A 46-year-old patient had incessant episodes of atrial fibrillation. He had previously undergone successful radiofrequency catheter ablation of a common atrial flutter. Antiarrhythmic drugs including amiodarone and various drug combinations were ineffective. A 7-French specially designed 14-polar catheter with interelectrode distance of 3 mm was used to create linear lesions in the right atrium. Each electrode was 4 mm in length and able to transmit radiofrequency energy. Three linear lesions, two longitudinal and one transverse that connected the two longitudinal lesions, were created using 30 radiofrequency applications of 10 to 40 W. The final application interrupted an atrial fibrillation that had been persistent for 55 minutes. No sustained atrial fibrillation was inducible despite repeated pacing maneuvers. There was no complication. In short-term follow-up of 3 months, the patient has been free of arrhythmias without antiarrhythmic medication. CONCLUSION: Successful catheter ablation of human atrial fibrillation is feasible using linear atrial lesions created by radiofrequency energy delivery. Further studies are mandatory to ascertain the efficacy and safety of this procedure, as well as to assess different catheter techniques.

Atrial Fibrillation↗
PubMed1994

Radiofrequency catheter ablation in unusual mechanisms of atrial fibrillation: report of three cases.

INTRODUCTION: The purpose of this study was to test the feasibility of radiofrequency (RF) catheter ablation of localized mechanisms of atrial fibrillation (AF). METHODS AND RESULTS: Three patients underwent RF catheter ablation for drug-resistant atrial arrhythmias. The first two patients had either incessant atrial tachycardia or AF. In the first patient, the ECG pattern of AF was mimicked by a very rapid atrial focus, whereas in the second patient, AF was due to true degeneration of the atrial activity triggered by atrial tachycardia. In both patients, the ablation of atrial focus led to the clinical disappearance of AF. The third patient had frequent episodes of AF, which lasted several days or weeks, and two documented episodes of atrial flutter. Mapping during AF showed an irregular atrial rhythm in the atrial septum, particularly in the region surrounding the coronary sinus, whereas the entire lateral right atrial free wall exhibited a constantly organized rhythm. RF energy was applied between the tricuspid ring and both the inferior vena cava and the coronary sinus, resulting in inability to reinduce atrial flutter or sustained AF. A 6-month follow-up in this patient showed the disappearance of prolonged episodes of AF. CONCLUSION: The observations indicate that AF may be linked to "focal" mechanisms that can be treated by RF catheter ablation.

Adult↗