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Biomedical subjects

A S Manolis

Publications and source records attributed to A S Manolis.

At least 37 records · Page 2Linked to original sources
PubMed2000

Dispersion of ventricular repolarization is determined by the presence of myocardial viability in patients with old myocardial infarction. A dobutamine stress echocardiography study.

AIMS: The study sought to investigate the relationship of myocardial viability detected by dobutamine stress echocardiography to changes of QT dispersion and to the presence of arrhythmias during dobutamine infusion in patients with old myocardial infarction. We also examined whether patency of the infarct-related artery is associated with the presence of myocardial viability and QT dispersion. BACKGROUND: QT dispersion and myocardial variability have been associated with the presence of arrhythmias during late post infarction but not during dobutamine stress. Restoration of anterograde coronary flow has beneficial effects on ventricular systolic function and repolarization, suggesting that the extent of viable myocardium may determine ventricular repolarization. METHODS: Seventy five patients with previous myocardial infarction were studied in a low dose (up to 20 microg(-1) x kg(-1) x min(-1)) dobutamine stress echocardiography study. ECGs were obtained at rest and peak stress for measurement of QT intervals. The presence of ventricular arrhythmias (Lown grade >lb) during stress was noted. A reduction in the total wall motion score of the left ventricle at peak stress confirmed the presence of myocardial viability. RESULTS: Dobutamine infusion increased QT dispersion in all patients (P<0.01). Patients with myocardial viability had a lower resting QT dispersion (P<0.05) and a greater increase in QT dispersion% (P<0.01) than patients without. The combination of a resting QT dispersion <65 ms or an increase in QT dispersion >30% predicted viability with a sensitivity of 67%, a specificity of 96%, and an accuracy of 78%. A patent infarct-related artery, as well as ventricular arrhythmias, were more commonly observed in patients with evidence of viable myocardium (P<0.05). Patients with arrhythmias had a higher QT dispersion than patients without (P<0.05). CONCLUSION: The combination of a resting QT dispersion +/-65 ms or an increase in QT dispersion >30% predicts the presence of viable myocardium and thus, may represent a simple index for the assessment of viability in everyday clinical practice. Myocardial viability is related to a patent coronary artery and to a high incidence of arrhythmias accompanied by a greater increase in QT dispersion at peak dobutamine infusion.

Arrhythmias, Cardiac↗
PubMed2000

Electrophysiologist-implanted transvenous cardioverter defibrillators using local versus general anesthesia.

With the advent of smaller biphasic transvenous implantable cardioverter defibrillators (ICDs) and the experience gained over the years, it is now feasible for electrophysiologists to implant them safely in the abdominal or pectoral area without surgical assistance. Throughout the years, general anesthesia has been used as the standard technique of anesthesia for these procedures. However, use of local anesthesia combined with deep sedation only for defibrillation threshold (DFT) testing might further facilitate and simplify these procedures. The purpose of this study was to test the feasibility of using local anesthesia and compare it with the standard technique of general anesthesia, during implantation of transvenous ICDs performed by an electrophysiologist in the electrophysiology laboratory. For over 4 years in the electrophysiology laboratory, we have implanted transvenous ICDs in 90 consecutive patients (84 men and 6 women, aged 58 +/- 15 years). Early on, general anesthesia was used (n = 40, group I), but in recent series (n = 50, group II) local anesthesia was combined with deep sedation for DFT testing. Patients had coronary (n = 58) or valvular (n = 4) disease, cardiomyopathy (n = 25) or no organic disease (n = 3), a mean left ventricular ejection fraction of 35%, and presented with ventricular tachycardia (n = 72) or fibrillation (n = 16), or syncope (n = 2). One-lead ICD systems were used in 74 patients, two-lead systems in 10 patients, and an AVICD in 6 patients. ICDs were implanted in abdominal (n = 17, all in group I) or more recently in pectoral (n = 73) pockets. The DFT averaged 9.7 +/- 3.6 J and 10.2 +/- 3.6 J in the two groups, respectively (P = NS) and there were no differences in pace-sense thresholds. The total procedural duration was shorter (2.1 +/- 0.5 hours) in group II (all pectoral implants) compared with 23 pectoral implants of group I (2.9 +/- 0.5 hours) (P < 0.0001). Biphasic devices were used in all patients and active shell devices in 67 patients; no patient needed a subcutaneous patch. There were six complications (7%), four in group I and two in group II: one pulmonary edema and one respiratory insufficiency that delayed extubation for 3 hours in a patient with prior lung resection, both probably related to general anesthesia, one lead insulation break that required reoperation on day 3, two pocket hematomas, and one pneumothorax. There was one postoperative arrhythmic death at 48 hours in group I. No infections occurred. Patients were discharged at a mean time of 3 days. All devices functioned well at predischarge testing. Thus, it is feasible to use local anesthesia for current ICD implants to expedite the procedure and avoid general anesthesia related cost and possible complications.

Adolescent↗
PubMed2000

Two-coil versus single-coil transvenous cardioverter defibrillator systems: comparative data.

Two types of new-generation transvenous implantable cardioverter defibrillator (ICD) systems, incorporating a two-coil (62 patients, group 1) versus single-coil (32 patients, group 2) lead system were compared among 94 consecutive patients. The two groups were comparable in age (58 +/- 13 vs 59 +/- 14 years), presenting arrhythmia (ventricular tachycardia versus ventricular fibrillation 77%/21% vs 84%/13%), cycle length of induced VT (294 +/- 4 vs 289 +/- 44 ms), number of unsuccessful antiarrhythmic drugs (1.7 +/- 0.8 vs 1.7 +/- 0.7), and left ventricular ejection fraction (35 +/- 12% vs 34 +/- 9%). Both systems were successfully implanted strictly transvenously in all patients. Biphasic shocks were used in all patients. Active shell devices were used in 79% and 84% patients of groups I and II, respectively (P = NS). Intraoperative testing revealed comparable defibrillation threshold (DFT) values (10.2 +/- 3.7 J in group 1 versus 9.3 +/- 3.6 J in group 2 system), and pacing threshold (0.7 +/- 0.3 vs 0.7 +/- 0.3 V), but R wave amplitude and lead impedance were lower in group 1 (13 +/- 5 vs 16 +/- 5 mV, P = 0.003; and 579 +/- 115 vs 657 +/- 111 ohms, P = 0.002, respectively). Lead insulation break requiring reoperation occurred in one patient with an Endotak lead, and two patients with Transvene leads had initially high DFT with a single one-lead/active can system, which was converted to a two- or three-endocardial-lead/inactive can configuration. We conclude that both single-coil and two-coil transvenous ICD systems were associated with high rates of successful strictly transvenous ICD implantation and a low incidence of lead-related complications. Significant differences were noted in the sensed R wave and lead impedance, probably reflecting the active fixation characteristics of the Transvene lead. However, in order to obviate the sporadic need for implantation of additional endocardial leads, as was the case in two patients in this series, a double-coil lead may be preferable.

Defibrillators, Implantable↗
PubMed1999

Detection of myocardial injury during radiofrequency catheter ablation by measuring serum cardiac troponin I levels: procedural correlates.

OBJECTIVES: In the present prospective controlled study, we measured blood levels of cardiac troponin I (cTnI) in patients undergoing radiofrequency (RF) catheter ablation (RFA), and we sought to investigate the degree of myocardial injury incurred by the application of RF energy and determine its procedural correlates. BACKGROUND: Measurement of serum creatine kinase (CK) levels after RFA may underestimate the degree of myocardial injury due to its thermal inactivation by RFA. Cardiac troponin I is a newer, more specific marker of myocardial injury, which may circumvent this limitation; its use in this setting has rarely been studied. METHODS: In 118 consecutive patients, 67 men and 51 women aged 38 +/- 19 years undergoing RFA for a variety of arrhythmias, cTnI and creatine kinase isoenzyme (CK-MB) levels were measured before, immediately after and 4 to 24 h after RFA. Cardiac troponin I was also measured in 39 patients (control group) having only electrophysiologic studies (EPS) without RFA. RESULTS: All RFA procedures were uncomplicated, lasted 3.2 +/- 2.0 h and included delivery of 16 +/- 22 (median: 9) RF current applications. Baseline cTnI levels averaged 0.17 +/- 0.18 ng/ml, rose to 0.88 +/- 1.12 at the end of RFA and to 2.19 +/- 2.46 at 4-24 h later. Creatine kinase isoenzyme was found to be elevated (>6 microg/l) in 32 patients (27%), while cTnI levels were increased (> or =1 ng/ml) in 80 patients (68%) (p = 0.0001). Cardiac troponin I levels correlated with the number of RF lesions applied (r = 0.53, p < 0.0001), the site of RFA, being higher with ventricular > atrial > annular lesions (p = 0.012) and the approach to the mitral annulus (transaortic > transseptal, p = 0.004). In a control group of 39 patients undergoing EPS, all but one patient had normal cTnI or CK-MB. CONCLUSIONS: The degree of myocardial injury incurred by RFA is far more accurately assessed by cTnI levels rather than by CK-MB measurements. Cardiac troponin I levels correlate with the number of RF lesions applied, the site of RFA and the approach to the mitral annulus.

Adolescent↗
PubMed1999

Radiofrequency ablation in older children and adolescents by an adult electrophysiology team.

BACKGROUND: Radiofrequency (RF) catheter ablation has been widely and successfully employed to cure adult patients of a variety of arrhythmias. Only a few centers have a pediatric electrophysiology (EP) service available and have presented similar results in children. The aim of this study was to investigate the efficacy and safety of RF ablation in pediatric patients performed by an adult EP team. PATIENTS AND METHODS: The study group included 33 consecutive pediatric patients, aged 7-18 years (mean 14.1 +/- 3.1), with symptomatic supraventricular tachyarrhythmias, who underwent RF ablation during the last 3 years. All but two patients underwent a full EP study during the same session. Procedures were performed in all but five patients with use of local anesthesia and deep or light sedation. The left heart was approached with use of transaortic (n = 3) or transseptal (n = 7) techniques. RF ablation was performed for manifest (n = 11) or concealed (n = 9) (9 left, 4 anteroseptal, 3 midseptal, and 4 posteroseptal) or right atriofascicular (Mahaim) (n = 1) accessory pathways in 19 patients, 12 slow AV nodal pathways and 2 atrial tachycardia foci in the other 14 patients. RESULTS: RF ablation was successful in all patients (100%) with 1-27 RF applications (mean: 10 +/- 7). There was one complication in a patient with 2 accessory pathways; after RF ablation of a posteroseptal accessory pathway, complete heart block occurred during successful ablation of a second midseptal accessory pathway. Fluoroscopy time averaged 35 +/- 23 min and procedure duration 2.8 +/- 1.4 hours. During long-term follow-up of 19 +/- 10 months, there was one AV nodal tachycardia recurrence at 2.5 months, successfully treated with repeat RF ablation. CONCLUSION: RF ablation in pediatric patients performed by an adult EP team is efficacious and safe offering cure of symptomatic cardiac tachyarrhythmias in this patient population.

Adolescent↗
PubMed1999

Percutaneous extraction of transvenous defibrillator leads using the VascoExtor pacing lead removal system.

In the implantable cardioverter defibrillator era the necessity for lead removal is not negligible. A specially designed extraction lead system for percutaneous removal of such leads is lacking, in contrast to the existing pacing lead extraction systems. We report the successful percutaneous extraction of four implantable cardioverter defibrillator leads in three patients because of lead malfunction using a novel pacemaker lead extraction system, the VascoExtor (VascoMed) system. Three leads were successfully removed in two patients using traction with special locking stylets from the superior approach. One lead was removed using the system's additional extraction tools through the femoral approach. There were no complications. This preliminary experience shows that the VascoExtor (VascoMed) pacemaker lead extraction system can also be used in implantable cardioverter defibrillator lead extraction safely and effectively. In addition to the locking stylets, adjunct percutaneous extraction tools may be needed in some cases.

Cardiovascular Surgical Procedures↗
PubMed1999

Pectoral cardioverter defibrillators: comparison of prepectoral and submuscular implantation techniques.

The purpose of this study was to compare the two techniques of pectoral ICD implantation, prepectoral and submuscular, performed by an electrophysiologist in the catheterization laboratory with use of general or local anesthesia in 45 consecutive patients. Over a period of 30 months, we implanted pectoral transvenous ICDs in 43 men and 2 women, aged 59 +/- 12 years, with use of general (n = 20) or local (n = 25) anesthesia in the catheterization laboratory. Patients had coronary (n = 30) or valvular (n = 4) disease, cardiomyopathy (n = 10) or no organic disease (n = 1), a mean left ventricular ejection fraction of 31%, and presented with ventricular tachycardia (n = 40) or fibrillation (n = 5). One-lead ICD systems (18 Endotak, 10 Transvene/8 Sprint, 2 EnGuard) were used in 38 patients, 2-lead (5 Transvene, 1 EnGuard) systems in 6 patients, and 1 atrioventricular lead ICD system in 1 patient. The prepectoral technique was employed in 29 patients with adequate subcutaneous tissue, while the submuscular technique was used in 16 patients who had a thin layer of subcutaneous tissue. The defibrillation threshold averaged 9-10 J in both groups and there were no differences in pace/sense thresholds. All implants were entirely transvenous with no subcutaneous patch. Biphasic ICD devices were employed in all patients. Active or hot can devices were used in 39 patients. There were no complications, operative deaths, or infections. Patients were discharged at a mean of 3 days. All devices functioned well at predis-charge testing. Over 14 +/- 8 months, 20 patients received appropriate device therapy (antitachycardia pacing or shocks). No late complications occurred. One patient died at 3 months of pump failure; there were no sudden deaths. In conclusion, for exclusive pectoral implantation of transvenous ICDs, electrophysiologists should master both prepectoral and submuscular techniques. One can thus avoid potential skin erosion or need for abdominal implantation in patients with a thin layer of subcutaneous tissue. Finally, there are no differences in pacing or defibrillation thresholds between the two techniques.

Adult↗
PubMed1998

Successful percutaneous extraction of pacemaker leads with a novel (VascoExtor) pacing lead removal system.

A new pacing lead extraction system (VascoExtor, VascoMed, Germany) with a universally applicable locking stylet was used over a period of 12 months to extract 25 permanent pacemaker leads (mean implantation time 3.9 +/- 3.8 years) in 16 patients who had pacemaker infection (n = 13), lead dysfunction (n = 2), or before an automatic defibrillator implant (n = 1). With use of this system, we were able to successfully and safely remove 24 of 25 chronic pacing leads (96%) in 15 of 16 patients (93%) with sole use of the locking stylet in 81%, and with use of an array of ancillary tools in the remaining 19% of patients.

Aged↗
PubMed1998

Idiopathic long QT syndrome with late onset of bradycardia-dependent and short-coupled variant of torsade de pointes.

We report an idiopathic variant of the long QT syndrome in a 72 year old woman with a history of recurrent syncope over 3 years who presented with repeated episodes of cardiac arrest due to bradycardia-dependent torsade de pointes (TdP), which continued long after possible triggers were eliminated. During these episodes a short coupling interval of the first tacycardia beat was also observed. The patient's stormy course was only controlled with pacing. She received a permanent dual-chamber pacemaker and prophylactically a beta-blocker was added. Over the subsequent 14 months she has remained completely asymptomatic.

Adrenergic beta-Antagonists↗
PubMed1998

Unusual features of right and left idiopathic ventricular tachycardia abolished by radiofrequency catheter ablation.

Two unusual cases are presented with idiopathic right and left ventricular tachycardia (IVT) with intriguing clinical and electrophysiological characteristics. The first patient with a sustained IVT of right ventricular outflow tract origin, and an electrophysiological mechanism suggesting reentry, had been resuscitated from cardiac arrest. The second patient had an IVT with a left bundle branch block morphology, which originated from the basal-septal region of the left ventricle (left ventricular outflow tract tachycardia). Both patients were cured with radiofrequency catheter ablation, guided by endocardial activation sequence and pace mapping.

Adult↗
PubMed1998

Pretreatment with antithrombotic agents during radiofrequency catheter ablation: a randomized comparison of aspirin versus ticlopidine.

INTRODUCTION: D-dimer is a product of fibrin degradation and can serve as a biochemical marker of thrombus formation and reactive fibrinolysis. According to our previous observations, and as reflected by elevated plasma D-dimer levels, lesions produced by radiofrequency (RF) ablation have a thrombogenic effect. Pretreatment with combined aspirin and ticlopidine mitigates this thrombogenicity; however, the effect of either agent alone remains unknown. METHODS AND RESULTS: In this study, 59 patients undergoing RF ablation were randomized to pretreatment with aspirin (group I; n = 30) or ticlopidine (group II; n = 29) for 3 days prior to RF ablation. D-dimer levels were measured by enzyme immunoassay before and after the electrophysiologic study (EPS), and both immediately and at 48 hours after RF ablation. Results also were compared with those of 31 patients (nonrandomized group III) who had received both aspirin and ticlopidine. At all stages, D-dimer levels were higher in groups I and II when compared with group III. Baseline D-dimer (31+/-20 vs 24+/-13 vs 17+/-11 microg/L, respectively; P = 0.002) rose after EPS to higher levels in groups I and II (91+/-100 microg/L and 51+/-35 microg/L) compared with group III (31+/-17 microg/L; P = 0.001). After RF ablation, D-dimer levels increased in all groups, but this increase was much higher in groups I and II (214+/-210 microg/L and 201+/-222 microg/L) than in group III (74+/-60 microg/L; P = 0.005). At 48 hours, D-dimer levels decreased in all groups, but remained higher in groups I and II (91+/-100 microg/L and 95+/-99 microg/L) than in group III (35+/-31 microg/L; P = 0.009). There were no differences among the three groups in the number of RF ablation lesions or the duration of the RF ablation procedure. CONCLUSION: Pretreatment with aspirin or ticlopidine alone does not decrease the thrombogenic potential of RF ablation. Only combined therapy with aspirin and ticlopidine has a favorable effect, as reflected by the lower degree of D-dimer elevation.

Adolescent↗
PubMed1997

Pretreatment with aspirin and ticlopidine confers lower thrombogenic potential of radiofrequency catheter ablation.

In the present study we pretreated 31 patients undergoing radiofrequency catheter ablation (RFA) with combined aspirin and ticlopidine for 3 days before the procedure, whereas 37 patients did not receive pretreatment. D-dimer levels reflecting the thrombogenic potential of RFA were significantly lower in the pretreated group at each stage before, during, and after the procedure, whereas there were no significant differences between the 2 groups in the number of RFA lesions or duration of the procedure.

Adolescent↗
PubMed1997

Abnormal signal-averaged electrocardiograms in patients with incomplete right bundle-branch block.

BACKGROUND AND HYPOTHESIS: A hypothesis was formulated that regional delayed activation of the right ventricle, as seen in incomplete right bundle-branch (IRBBB) aberrancy, may simulate late potential activity and may be responsible for abnormal signal-averaged electrocardiograms (SAECGs). No previous studies have specifically addressed this issue in this particular group of patients (with IRBBB). Therefore, the aim of the present study was to investigate the incidence of abnormal SAECGs in patients with IRBBB. If this were confirmed, our purpose would further be to investigate ways of reducing the false positive results. METHODS: The study group included 53 patients (28 men and 25 women), aged 53 +/- 13 years, with no history of previous myocardial infarction or ventricular tachycardia and who had an electrocardiogram (ECG) showing IRBBB. An SAECG was also performed in a control group of 19 age-matched individuals with a normal ECG. Time domain analysis was performed using a band pass filter of 40-250 Hz. The following parameters were considered normal: filtered QRS duration (QRSD) < 114 ms, root mean square of the voltage of the last 40 ms of the QRS complex (RMS) > 20 microV, and the duration of the low amplitude signal (< 40 microV) at the terminal portion of the QRS (LAS) < 38 ms. An SAECG was considered abnormal if any two of these criteria were abnormal. RESULTS: The mean values of the SAECG parameters were: QRSD 101 +/- 11 ms, RMS 32 +/- 20 microV, LAS 32 +/- 12 ms, and noise 0.29 +/- 0.13 microV. Abnormal SAECGs with at least two criteria satisfied were present in 16 of 53 (30%) patients compared with 0 (0%) of 19 individuals in the control group (p = 0.02). Abnormal values included the combination of RMS and LAS in 12 patients and all three parameters in 4 patients. However, if the definition of late potentials were limited to the combination of abnormal QRSD and either RMS or LAS values, the incidence of false positive results (4 patients) (7.5%) would be significantly decreased (p = 0.007). At 21 months of follow-up, no arrhythmic events occurred. CONCLUSIONS: Delayed terminal conduction observed in IRBBB may cause a high incidence of false positive late potentials on SAECGs. Based on this study, we propose that this can be largely remedied if the optimal criteria for the presence of late potentials in patients with IRBBB always include the combination of QRSD and either RMS or LAS.

Action Potentials↗
PubMed1997

Transvenous defibrillator systems implanted by electrophysiologists in the catheterization laboratory.

BACKGROUND: A significantly lower perioperative mortality has established the nonthoracotomy approach as the preferred technique in implantable cardioverter defibrillation (ICD) implantation. With the currently available transvenous endocardial leads in combination with the expanded use of biphasic ICD devices, the need for use of an additional subcutaneous lead has almost been eliminated. Thus, implantation of these systems has been simplified and reports have appeared in the literature that the procedure can now be performed by an electrophysiologist alone without surgical assistance in the electrophysiology or catheterization laboratory. HYPOTHESIS: The purpose of this study was to investigate the feasibility and safety of ICD implantation by an electrophysiologist in a procedure performed entirely in the catheterization laboratory without the assistance of a surgeon. METHODS: Over a period of 28 months, we implanted transvenous ICDs in 40 consecutive patients with (n = 34) and without (n = 6) use of general anesthesia in the catheterization laboratory with minor surgical assistance in abdominal pocket fashioning for the first two cases and then working alone for the remainder. The study included 36 men and 4 women, aged 59 +/- 12.5 years, with coronary artery (n = 22) or valvular heart disease (n = 4), cardiomyopathy (n = 12), and long QT syndrome (n = 1) or idiopathic ventricular tachycardia (n = 1), and a mean left ventricular ejection fraction of 34%, who presented with ventricular tachycardia (n = 30) or ventricular fibrillation (n = 10). RESULTS: One-lead ICD systems (Endotak, n = 21; Transvene, n = 8; or EnGuard, n = 1) were used in 30 patients, and 2-lead (EnGuard, n = 5 or Transvene, n = 5) systems in 10 patients. Generators were implanted in an abdominal (n = 17) or pectoral (n = 23) pocket. Active can devices were employed in 17 patients. The defibrillation threshold averaged 9 J. All implants were entirely transvenous with no subcutaneous patch. Biphasic ICD devices were employed in all patients. There were three complications (8%); one pulmonary edema that responded to drug therapy, one lead insulation break that required reoperation on the third day, and one pocket hematoma in a patient receiving anticoagulation, with no need for evacuation. There were no operative deaths and no infections. After implant, patients were discharged at a mean of 3 days. All devices functioned well at predischarge testing. During follow-up (12 +/- 8 months), 20 patients received appropriate and 5 patients inappropriate shocks. Three patients died of pump failure at 3, 7, and 19 months, respectively; they had received 0, 42, and 15 appropriate shocks, respectively, over these months. Another patient succumbed to a myocardial infarction at 9 months. At 6 months, one patient developed subacute subclavian vein thrombosis which resolved with anticoagulation therapy. CONCLUSIONS: Current transvenous biphasic ICD systems allow experienced electrophysiologists to implant them safely alone in the catheterization laboratory without surgical assistance, even for abdominal implants, with a high success rate and no need for use of a subcutaneous patch.

Adult↗
PubMed1997

Comparison of signal-averaged electrocardiograms with different levels of noise: time-domain, frequency-domain, and spectrotemporal analysis.

In order to test the effect of noise on the various parameters of the SAECG, 83 patients underwent three consecutive recordings at different noise levels. The high noise (HN) recordings had a noise level of 0.60-0.74 microV, the intermediate noise (IN) had 0.31-0.59 microV, and the low noise (LN) had < or = 0.30 microV. For the calculation of noise we used the standard deviation of the mean noise of the composite lead high pass filtered at 40 Hz. The recordings were compared using time-domain, frequency-domain, and spectrotemporal analysis. The time-domain parameters of the LN recordings, using 25-Hz, 40-Hz, and 60-Hz high pass cutoffs, were significantly different from those of the HN or IN recordings (P < 0.05). In the frequency-domain analysis, significant differences were found in some of the parameters of the LN compared to the HN. The spectrotemporal analysis of the X and Z leads also showed significant differences among the LN and the other recordings. In the time-domain analysis, both at 40 Hz and 25 Hz, there were more abnormal LN compared to the HN recordings (P < 0.05). In the spectrotemporal analysis, there were significantly more abnormal HN and IN recordings compared to the LN (P < 0.001 and P < 0.01, respectively). Therefore, the level of noise, even within the acceptable range, can significantly affect the SAECG. In the time domain at the lower noise levels the parameters become more abnormal, while the opposite seems to occur in the spectral and the spectrotemporal analysis.

Electrocardiography↗
PubMed1997

Successful radiofrequency catheter ablation of automatic atrial tachycardia with regression of the cardiomyopathy picture.

Ectopic atrial tachycardia (EAT) is often refractory to pharmacological suppression, and if uncontrolled, it can lead to cardiomyopathy. Although RF current catheter ablation therapy has been effective in eliminating the arrhythmia, there is limited information, particularly in adult patients with regard to the reversal of the tachycardia induced cardiomyopathy. Four adult patients, 20-56 years of age, and a 6-year-old boy, were referred with refractory EAT. Four patients had heart failure and three had depressed LV function by echocardiographic criteria. All patients underwent electrophysiological study, and RF ablation was successful in abolishing the arrhythmogenic foci. Of these, four were located in the right atrium and one in the left atrium, and were identified by recording of the earliest atrial activation. No complications occurred. Termination of the EAT resulted in symptomatic improvement. Serial echocardiographic assessment of LV function indicated a significant reversal of the cardiomyopathy picture with reduction in chamber size and recovery in systolic function; indices of diastolic dysfunction persisted in one patient. Chronic, uncontrolled EAT can cause tachycardia induced cardiomyopathy. The picture of the cardiomyopathy resolves after elimination of the focus. RF ablation is both effective and safe, and may be considered as early therapy, particularly in patients with incessant EAT and ventricular dysfunction.

Adult↗
PubMed1996

Thrombogenicity of radiofrequency lesions: results with serial D-dimer determinations.

OBJECTIVES: By measuring plasma levels of D-dimer, a product of fibrin degradation, we sought to investigate whether the application of radiofrequency (RF) energy might activate endogenous thrombotic mechanisms. BACKGROUND: Quantitative determination of D-dimer, a bio-chemical marker of thrombus formation and reactive fibrinolysis, helps to diagnose activation of the coagulation system. It remains controversial whether endocardial lesions produced during RF catheter ablation of arrhythmogenic foci have a thrombogenic effect, and the issue of the need for antithrombotic therapy after RF ablation is still unresolved. METHODS: We made serial determinations of plasma D-dimer levels by enzyme immunoassay before insertion of catheters, after completion of electrophysiologic study (EPS) but before RF ablation, immediately after RF ablation and before discharge (at 48 h) from the hospital in 37 patients undergoing RF ablation (22 men, 15 women; mean [+/-SD] age 37 +/- 18 years, range 12 to 74; 16 +/- 16 lesions produced) of accessory (n = 17) or slow (n = 12) pathways, atrial (n = 4) or ventricular foci (n = 3) or the atrioventricular node (n = 1). D-dimer levels were also measured in 26 age-matched control subjects undergoing EPS only. RESULTS: In the RF ablation group, the mean D-dimer levels increased from a baseline value of 29 +/- 28 to 62 +/- 56 micrograms/liter after EPS (p < 0.0001). However, after RF ablation, D-dimer levels increased to much higher levels (188 +/- 138 micrograms/liter, p < 0.0001). There was no correlation of D-dimer levels with the number of RF lesions produced or the duration of the procedure. At 48 h after the procedure, D-dimer levels decreased (75 +/- 67 micrograms/liter) but still remained significantly elevated compared with baseline values (p = 0.0001). Three were no significant differences in baseline (25 +/- 21 micrograms/liter) and post-EPS (51 +/- 50 micrograms/liter) measurements between control subjects and patients. During RF ablation, intravenous heparin was given to nine patients who still demonstrated high plasma D-dimer levels after RF ablation. CONCLUSIONS: As reflected by elevated plasma D-dimer levels, RF ablation has a thrombogenic effect that persists through 48 h after the procedure. This effect needs to be taken into account when considering antithrombotic therapy in patients undergoing RF ablation.

Adolescent↗