Electrocardiogram abnormalities in older individuals by race and ethnicity.

BACKGROUND: Aging is associated with many ECG changes. ECG abnormalities are known to be more prevalent with age and differ across race and ethnicity, yet there are limited studies categorizing the ECG changes in the older population and the differences seen among racial groups. We sought to determine ECG differences associated with race and ethnicity in this ethnically diverse, elderly population. METHODS: The ECG parameters of subjects between the ages of 75 and 99 years from a large and diverse inner-city patient population were analyzed. Subjects were grouped into one of four categories: Hispanic, Black, Non-Hispanic White, or Other for analysis. Rhythm, axis, voltage, and conduction parameters were determined according to the 12 SL algorithm and interpretation statements (GE Healthcare, Wauwatosa, Wisconsin) that were confirmed by an overreading cardiologist. RESULTS: 38,238 subjects were included. Of all groups, Non-Hispanic Whites exhibited more conduction abnormalities such as bundle branch block compared to the other groups, as well as the highest incidence of atrial fibrillation (AF) (12.6%, p < 0.05). Hispanics had the highest proportion of normal sinus rhythm. Blacks exhibited the least amount of AF (6.3%), as well as the highest incidence of LVH (25.5%), RAD (13.5%), and the largest percentage of abnormal ECGs (72.8%). CONCLUSION: Significant differences among the elderly of different race and ethnicity were noted with most parameters.

Exacerbation of ventricular arrhythmias during the postoperative period after implantation of an automatic defibrillator.

The postoperative course of 68 consecutive patients treated with an implantable defibrillator during the period from 1982 through 1990 was studied. In 46 patients (group 1), no concomitant surgery was performed during the implantation. In 22 patients (group 2), concomitant surgery (coronary artery bypass [n = 12], valve replacement [n = 3] or arrhythmia surgery [n = 7]) was performed. All patients in group 1 were clinically stable before surgery, receiving an antiarrhythmic regimen chosen by serial drug testings. The same regimen was continued postoperatively. Eight of the 46 patients in group 1 whose condition had been stable in the hospital for 19 +/- 25 days preoperatively developed multiple episodes of sustained ventricular tachycardia 4 +/- 9 days after implantation while receiving the same antiarrhythmic regimen. Although the exacerbation was transient in some patients, six required different antiarrhythmic therapy and one eventually died. Two additional patients had frequent and prolonged episodes of nonsustained ventricular tachycardia that could trigger the defibrillator, requiring changes in the antiarrhythmic regimen. Another patient had progressive cardiac failure and died on day 5. A marked (sevenfold) increase in asymptomatic ventricular arrhythmias was noted in 42% of the remaining 35 patients. In group 2 (combined surgery), one patient developed refractory ventricular tachycardia 3 days postoperatively and died on that day. Three patients developed frequent nonsustained ventricular tachycardia postoperatively, requiring changes in the antiarrhythmic regimen. The overall surgical mortality rate was 4.4% (4.3% in group 1 and 4.5% in group 2) and was due to refractory ventricular tachycardia in two patients and cardiac failure in one.(ABSTRACT TRUNCATED AT 250 WORDS)

Benefits of implantable defibrillators are overestimated by sudden death rates and better represented by the total arrhythmic death rate.

Benefits of the implantable defibrillator on survival were studied in 56 consecutive patients (concomitant coronary bypass or arrythmia surgery in 15) during an 8 year period between 1982 and 1990. During a follow-up period of 29 +/- 25 months, six patients had a sudden death and eight patients had a nonsudden cardiac death. Nonsudden cardiac deaths included three surgical deaths (death within 30 days after the surgery; two in patients without and one in a patient with concomitant cardiac surgery), one arrhythmia-related nonsudden death (death within 24 h after an arrhythmic event despite initial termination of the arrhythmia by the implantable defibrillators) and four nonarrhythmic cardiac deaths. The actuarial survival rate free of events at 1, 2 and 3 years was 96%, 96% and 92%, respectively, for sudden death, 91%, 91% and 87% for sudden death and surgical mortality and 89%, 89% and 85% for total arrhythmic death (sudden death, surgical mortality and arrhythmia-related nonsudden death). Thus, in patients treated with an implantable defibrillator, 1) the rate of sudden death is low (8% at 3 years); 2) 50% of nonsudden cardiac deaths are causally related to arrhythmia (surgical mortality or arrhythmia-related nonsudden death); 3) the total arrhythmic death rate is substantially higher than the sudden death rate; and 4) benefits of an implantable defibrillator are overestimated by reported sudden death and nonsudden cardiac death rates. The benefits may be better represented by the total arrhythmic death and nonarrhythmic cardiac death rates.

Comparison of left ventricular cryolesions created by liquid nitrogen and nitrous oxide.

OBJECTIVES: This study was designed to compare the cryosurgical lesions produced by liquid nitrogen (-196 degrees C) and nitrous oxide (-76 degrees C). BACKGROUND: Cryosurgical ablation is a useful method of arrhythmia surgery, but information on the dimensions of cardiac lesions produced by modifying cryoprobe temperature is limited. METHODS: We compared the dimensions, volumes and electrophysiologic effects of cryolesions created by a liquid nitrogen cryoprobe (Group I) and a nitrous oxide cryoprobe (Group II) on the left ventricular myocardium in the beating canine heart. Exposure time was compared at 1, 2, 3 and 4 min. In each of 18 dogs, two to four lesions were created on the left ventricle and analyzed: 35 lesions created with use of the nitrous oxide cryoprobe and 30 lesions created with the liquid nitrogen cryoprobe. Lesions were measured at the time of induced death 6 weeks postoperatively and assessed by tissue staining with the Masson trichrome technique. RESULTS: The volumes (mm3) of the cryolesions created by the liquid nitrogen cryoprobe were significantly larger (p < 0.05) than those of lesions created by nitrous oxide: 826 +/- 163 versus 493 +/- 197 at 1 min; 1,101 +/- 327 versus 666 +/- 185 at 2 min; 1,356 +/- 318 versus 787 +/- 258 at 3 min and 1,735 +/- 534 versus 923 +/- 376 at 4 min. CONCLUSIONS: Decreasing the temperature of the cryoprobe by using liquid nitrogen increases the volume of the lesions. Programmed electrical stimulation before and 6 weeks after cryoablation indicated no arrhythmogenicity.

Minimal cardiac effects in asymptomatic athyreotic patients chronically treated with thyrotropin-suppressive doses of L-thyroxine.

Biondi, Fazio, and colleagues recently reported that long term T4 treatment to suppress serum TSH markedly affects cardiac function. T4-treated patients had more symptoms [12.2 +/- 3.9 (+/-SD) vs. 4.2 +/- 2.3 by quantitative questionnaire], higher mean heart rate, increased incidence of atrial extrasystoles, increased interventricular septal thickness and left ventricular mass index (LVMi), and significant diastolic dysfunction. The severity of cardiac abnormalities was highly correlated with scores of a rating scale used for assessing symptoms of thyrotoxicosis. We have duplicated their studies in 17 athyreotic patients (mean age, 45 +/- 10 yr; range, 27-63 yr) without heart disease or hypertension whose dose of T4 was titrated to suppress serum TSH to less than 0.01 microU/mL. The mean duration of T4 treatment was 9.2 +/- 5.4 yr. Controls were healthy volunteers matched for sex and age (+/-3 yr). The mean T4 dose was 2.8 +/- 0.9 micrograms/kg (0.192 +/- 0.058 mg/day). By questionnaire, patients had minimal symptoms, although their symptom score was significantly greater than the control value (4 +/- 3 vs. 2 +/- 1; P < 0.05; maximum score, 36). No differences in mean heart rate or in atrial or ventricular extrasystoles were noted. In patients, indexes of systolic and diastolic function and interventricular septal thickness were similar to control values. The mean LVMi was normal in both groups. However, the mean LVMi in patients (117 +/- 35 g/m2) was higher than that in controls (92 +/- 31; P < 0.05). In conclusion, patients were minimally affected by TSH-suppressive doses of T4. They had few symptoms and no increase in extrasystoles or basal heart rate. Based on current knowledge, the increase in LVMi observed in patients without associated significant systolic or diastolic abnormalities does not have clinical or prognostic importance. Therefore, in the absence of symptoms of thyrotoxicosis, patients treated with TSH-suppressive doses of L-T4 may be followed clinically without specific cardiac laboratory studies.

Effect of digitalis treatment on survival after acute myocardial infarction.

To determine whether treatment with digitalis is associated with decreased survival after acute myocardial infarction (AMI), data from 504 patients who were enrolled in a postinfarction natural history study were analyzed. At the time of discharge, 229 patients (45%) were taking digitalis. After 3 years of follow-up, the cumulative survival rate for patients discharged on a regimen of digitalis was 66%, compared with 87% for those not treated (p less than 0.001). Univariate analysis showed that statistically significant differences existed between the 2 groups with respect to age, previous AMI, left ventricular failure in the coronary care unit, atrial fibrillation in the coronary care unit, peak creatine kinase levels, enlarged heart and pulmonary vascular congestion on the discharge chest x-ray, ventricular arrhythmias and treatment with diuretic, antiarrhythmic and beta-blocking drugs. Survival analysis using Cox's regression model showed that the association between digitalis and decreased survival was of borderline significance after adjustment for atrial fibrillation and left ventricular failure. Serum digoxin concentration was measured in 83% of the patients who took digitalis. Survival was inversely and significantly related to serum digoxin, i.e., the higher the serum digoxin concentration, the lower the long-term survival rate. After adjusting for atrial fibrillation and left ventricular failure, serum digoxin was not significantly related to survival. Taken together with the results of 3 other large, nonrandomized studies of digitalis treatment after AMI, this study suggests that digitalis treatment may have adverse effects on survival during follow-up.(ABSTRACT TRUNCATED AT 250 WORDS)

Evaluation of end points of serial drug testing in patients with sustained ventricular tachycardia after healing of acute myocardial infarction.

Serial electrophysiologic drug testing was used to guide antiarrhythmic therapy in a consecutive series of 150 patients with clinical sustained ventricular tachycardia (VT) or cardiac arrest and inducible monomorphic VT. All patients had coronary artery disease and a history of myocardial infarction. For patients with clinical sustained VT, drug responders and partial drug responders (VT slowed by drug to rate < 150 beats/min, with systolic blood pressure > or = 90 mm Hg) had similar total mortality rates (2-year actuarial survival 100% and 94%, p = NS), which were statistically different from that of patients with drug inefficacy (2-year survival 67%). Partial drug responders had high arrhythmia recurrence rates, similar to those of patients with drug inefficacy. For cardiac arrest survivors, the results of electrophysiologically guided drug testing did not predict prognosis. Patients with a change in mode of VT induction during antiarrhythmic therapy had a favorable prognosis (no deaths during follow-up).

Comparison and frequency of ventricular arrhythmias after defibrillator implantation by thoracotomy versus nonthoracotomy approaches.

Postoperative exacerbation of ventricular arrhythmias has been reported in some patients treated with thoracotomy implantable cardioverter-defibrillators (ICDs). This phenomenon, which may be related to epicardial patch electrodes, may be less frequent after nonthoracotomy ICD implantation. In this nonrandomized study, postoperative arrhythmias in thoracotomy approaches (n = 52) were compared with those in nonthoracotomy approaches (n = 59). Preoperatively, all patients were clinically stable receiving an antiarrhythmic regimen chosen by serial drug testing. Nine of 52 patients in the thoracotomy group developed sustained ventricular tachycardia postoperatively while receiving the same antiarrhythmic regimen chosen preoperatively, and 1 patient eventually died. Two additional patients developed frequent and prolonged episodes of nonsustained ventricular tachycardia requiring changes in the antiarrhythmic regimen. In the nonthoracotomy group, only 3 of 59 patients developed sustained ventricular tachycardia and 1 developed frequent nonsustained ventricular tachycardia. Thus, only 4 of 59 patients in the nonthoracotomy group developed clinically significant ventricular arrhythmia during the postoperative period compared with 11 of 52 patients in the thoracotomy group (p < 0.05). Surgical mortality was 6% in the thoracotomy group, and 0% in the nonthoracotomy group. In the remaining clinically stable patients, a marked (sevenfold) increase in asymptomatic ventricular arrhythmias was noted in 15 of 39 patients in the thoracotomy group, and in 3 of 55 patients in the nonthoracotomy group (p < 0.05). Thus, postoperative exacerbation of ventricular arrhythmia, sometimes noted with thoracotomy approaches, is very rare with nonthoracotomy approaches.

Long-term outcomes and modes of death of patients treated with nonthoracotomy implantable defibrillators.

Long-term outcomes of all patients who underwent nonthoracotomy implantable cardioverter-defibrillator (ICD) implantation at our institution from April 1991 to October 1994 were studied using the intention-to-treat analysis. Of 94 consecutive patients, 81 underwent nonthoracotomy ICD implantation and 13 underwent thoracotomy (for concomitant surgery in 11 and unavailability of nonthoracotomy leads in 2). Six of 81 patients had a high defibrillation threshold, 4 subsequently underwent thoracotomy, and 2 were treated with amiodarone. Surgical mortality was 0%. The duration of follow-up was 20 +/- 13 months, and was > 12 months in 74% of 67 living patients. Actuarial survival rates at 1 and 2 years were, respectively, 98% and 94% for sudden death and 91% and 83% for total mortality. Deaths during long-term follow-up were mostly due to nonsudden cardiac or noncardiac deaths. Two-year mortality rates were 12% and 25% in patients with ejection fraction > or = 30% and < 30%, respectively. Thus, instances of sudden death and surgical mortality are very few in patients with nonthoracotomy ICDs. Deaths during long-term follow-up are mostly due to nonsudden cardiac and noncardiac deaths. Therefore, ICD therapy may have greater impact on survival in patients with lower risks of nonsudden cardiac and cardiac death (e.g., younger patients with minimal heart disease) than in patients with severe cardiac or noncardiac disease. Prospective studies are needed to address this question.

Reproducibility of electrophysiologic testing during antiarrhythmic therapy for ventricular arrhythmias secondary to coronary artery disease.

Although electrophysiologic studies are often used to assess antiarrhythmic drug efficacy in patients with ventricular tachycardia (VT), the reproducibility of these studies during therapy has not been definitively established. Confirmation studies were performed during drug therapy in 64 patients (51 men, mean age 63 years) with sustained ventricular arrhythmias induced during initial study to assess the reproducibility of drug effect. All patients had coronary artery disease. The stimulation protocol used included the serial introduction of up to 3 premature ventricular stimuli during sinus rhythm and with ventricular pacing at 2 pacing rates. Rapid ventricular pacing techniques were also used. Antiarrhythmic drug efficacy was confirmed in 77% of patients. Sustained VT was induced at repeat electrophysiologic study in 19% of patients during antiarrhythmic therapy that was previously thought to be effective. In summary, electrophysiologic study results during antiarrhythmic therapy exhibit significant day-to-day variability. Sustained VT can be induced during antiarrhythmic therapy that was previously defined as effective by programmed stimulation in a substantial number of patients.

Internal transcardiac pericardiocentesis for acute tamponade.

If the catheter is still in the pericardium when tamponade is recognized during catheterization or electrophysiologic procedures, it can be used for definitive aspiration and relief of tamponade. This is physiologically beneficial to the patient, and psychologically beneficial to both patient and medical staff.

Comparison of defibrillator therapy and other therapeutic modalities for sustained ventricular tachycardia or ventricular fibrillation associated with coronary artery disease.

Outcomes of 282 patients referred to the arrhythmia service at Montefiore Medical Center for sustained ventricular tachycardia (n = 214) or ventricular fibrillation (n = 68) associated with coronary artery disease were analyzed retrospectively. All patients underwent serial drug trials by electrophysiologic testing and Holter monitoring. Sixty-eight patients who did not respond to drug therapy were treated with implantable cardioverter-defibrillators (ICD group), and 214 patients were treated with other methods guided by electrophysiologic testing and Holter monitoring (non-ICD group). The non-ICD group included 49 patients who responded to drug therapy as judged by electrophysiologic testing, as well as patients who did not respond and were not treated with defibrillator therapy for various reasons. Ten patients died in the hospital (2 patients in the ICD group, 8 in the non-ICD group). Actuarial survival rates free of total cardiac death at 1, 2, and 3 years were, respectively, 94%, 87%, and 85% in the ICD group, and 82%, 78%, and 73% in the non-ICD group (p = NS). Survival rates free of total death at 1, 2, and 3 years were 90%, 82%, and 76% in the ICD group, and 82%, 76%, and 70% in the non-ICD group, respectively (p = NS). Survival rates free of total cardiac and total deaths of 49 patients treated with an effective regimen determined by electrophysiologic testing were not significantly different from those of the ICD group. This retrospective study suggests that outcomes of patients treated with ICDs may not be dramatically different from those of patients treated with other methods guided primarily by electrophysiologic testing.(ABSTRACT TRUNCATED AT 250 WORDS)

Influence of left ventricular function on survival and mode of death after implantable defibrillator therapy (Cleveland Clinic Foundation and Montefiore Medical Center experience).

To determine the influence of left ventricular (LV) function on survival and mode of death in patients with an implantable cardioverter-defibrillator (ICD), sudden death, surgical mortality, total arrhythmia-related death, total cardiac death and total death were retrospectively evaluated in 377 consecutive patients. The outcomes were also compared between patients with an LV ejection fraction > or = 30% (214 patients, group 1) and < 30% (148 patients, group 2). Surgical mortality was 3.9% (1.8% in group 1, 7% in group 2). During the follow-up of 25 +/- 20 months, actuarial survival rates of all patients at 3 years were 96% for sudden deaths, 81% for total cardiac deaths and 74% for total mortality. When the 2 groups were compared, survival rates of groups 1 and 2 at 3 years, respectively, were 99 and 90% for sudden death (p < 0.05), 97 and 84% for sudden death and surgical mortality (p < 0.01), 94 and 80% for the total arrhythmia-related death (p < 0.001), 88 and 68% for total cardiac death (p < 0.0001), and 81 and 62% for total mortality (p < 0.002). In group 2, 73% of total cardiac deaths within 1 year were causally related to the arrhythmia. Thus, in patients with an ICD, sudden death rates were very low. However, total cardiac death and total death rates were relatively higher. The outcomes of patients with an ICD were strongly influenced by the degree of LV dysfunction.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison of long-term outcomes of patients treated with nonthoracotomy and thoracotomy implantable defibrillators.

In 193 consecutive patients treated with implantable defibrillators at our institution, thoracotomy approaches were used in 87 patients and nonthoracotomy approaches in 106 patients. Long-term outcomes of the 2 groups were compared by the intention-to-treat analysis. Surgical mortality (30-day mortality) rates were 5.7% in the thoracotomy group and 0% in the nonthoracotomy group. Six of 106 patients who underwent nonthoracotomy implantation had a high defibrillation threshold and did not receive nonthoracotomy defibrillators. The duration of follow-up was 52 +/- 31 months in the thoracotomy group, and 23 +/- 15 months in nonthoracotomy group. Actuarial survival rates at 6 and 24 months were, respectively, 90% and 81% in nonthoracotomy patients and 89% and 80% in thoracotomy patients (p = NS). In patients with left ventricular ejection fraction <30%, surgical mortality was 0% by the nonthoracotomy and 10% by the thoracotomy approach. Despite the 10% difference in 30-day mortality, survival rates at 6 months were 85% in nonthoracotomy patients and 81% in thoracotomy patients. At 24 months they were 73% in nonthoracotomy patients and 74% in thoracotomy patients. Thus, this nonrandomized study suggests that while short-term survival is better in nonthoracotomy patients than thoracotomy patients, the difference in survival diminishes quickly during the first few months and disappears by 6 months. The results were similar in patients with severe ventricular dysfunction. Several important implantable-cardioverter defibrillator (ICD) trials initially utilized thoracotomy ICDs. Although questions may be raised with regard to applicability of such a trial in the era of nonthoracotomy ICDs, this study suggests that the results of such ICD trials will be largely applicable to patients treated with nonthoracotomy ICDs.

ICD implantation via thoracoscopy, "mailslot" thoracotomy, and subxiphoid incision.

An improved method of thoracoscopic implantable cardioverter defibrillators implantation is described. "Mailslot" thoracotomy is more expeditious than thoracoscopic implantation via multiple ports. If required for adequate defibrillation thresholds, subxiphoid, subdiaphragmatic implantation of a defibrillator patch may be performed.

Case report: is this SVT or VT? An exception to the rule.

This case illustrates the difficulties sometimes encountered by clinicians when using algorithms in diagnosing a wide-complex tachycardia based on a 12-lead EKG.

Ultrarapid train stimulation versus conventional programmed electrical stimulation for induction of ventricular arrhythmias in patients with coronary artery disease.

Conventional programmed electrical stimulation (PES) of the ventricle is useful for establishing inducibility or noninducibility of clinical ventricular arrhythmias (VA) but is complex and time consuming. The present study was designed to compare a standard PES protocol with an alternative method using ultrarapid train stimulation in patients with VA and coronary artery disease (CAD). A prospective, randomized, crossover design was used. During each session in the electrophysiology laboratory, patients were studied using both the trains and PES protocols in randomized order. In 82 matched pairs of comparisons in 50 patients, results were concordant in 85% (p < 0.0001). There were no differences related to type of clinical arrhythmia or to the presence of antiarrhythmic drugs. There were no significant differences in the induction of nonclinical arrhythmias with the two methods (p < 0.0001 for concordance). There were no significant differences related to the cycle length of the trains (10, 20, or 30 ms, equivalent to 100, 50, or 33 Hz). The number of drive-extrastimuli sequences and the time required to complete the trains protocol was significantly shorter (p < 0.0001) using trains versus PES. Ultrarapid train stimulation provides results in CAD patients that are comparable with those of conventional PES protocols. There is a significant savings in time, adding practical value to intrinsic electrophysiologic interest. Trains may be useful when multiple inductions are desirable, for example, in the setting of antitachycardia pacing parameters in an implantable defibrillator (ICD), during ICD implantation, or in other circumstances where the main question is inducibility of ventricular arrhythmias.

Cardiac memory after radiofrequency ablation of accessory pathways: the post-ablation T wave does not forget the pre-excited QRS.

INTRODUCTION: Normalization of the pre-excited QRS following ablation is accompanied by repolarization changes but their directional relationship to changes in ventricular activation has not been well characterized. METHODS: Accordingly, we measured QRS and T wave vectors and QRS-T angles from 12 lead ECG recordings immediately before and after accessory pathway (AP) radiofrequency ablation in 100 consecutive patients. Patients with bundle branch block, intraventricular conduction defect or intermittent pre-excitation were excluded, leaving a study group of 45 patients: 35 with pre-excitation and 10 with concealed APs. RESULTS: With AP ablation, changes occurred in the QRS and T wave vectors and QRS-T angles that were essentially equal and opposite, so that the newly normalized QRS complex and QRS vector were accompanied by a T wave whose vector approximated that of the pre-ablation QRS vector. This tended to maintain a large QRS-T angle: 72 degrees +/- 50 degrees before, and 54 degrees +/- 34 degrees after QRS normalization (p = NS). A QRS-T angle >40 degrees was found before and after ablation in 22/35 patients (63%) with baseline pre-excitation; but never in patients with a concealed AP (p = 0.001). The angle between the pre-excited QRS and the post-ablation T wave was 35 degrees +/- 37 degrees, and

Symptomatic improvement after AV nodal ablation and pacemaker implantation for refractory atrial fibrillation and atrial flutter.

Symptomatic Improvement was evaluated in 64 patients with drug-refractory atrial fibrillation or atrial flutter who underwent atrioventricular (AV) nodal ablation and permanent pacemaker implantation. The arrhythmias were chronic in 40 patients and paroxysmal in 24 patients. All were refractory to multiple drugs (3.7 +/- 1.5) and had severe symptoms: palpitations (58 patients), dyspnea (n=58), dizziness (n=38), asthenia (n=37), and chest pain (n=20). All underwent AV nodal ablation and single- (n=39) or dual-chamber (n=25) pacemaker implantation. During follow-up of 20.4 +/- 17.8 months, palpitations improved in 100% of 58 patients who had palpitations before the ablation, dyspnea improved in 75% of 58 patients, chest pain in 95% of 20 patients, asthenia in 75% of 37 patients, and dizziness in 93% of 38 patients. Moderate to significant improvement in these symptoms was reported in 83% of patients and mild improvement in 5%. Before ablation, 77% of patients were in New York Heart Association functional class III or IV. After ablation, 19% of patients were in the same functional classes (P < 0.05). Thus, AV nodal ablation and pacemaker implantation in patients with drug-refractory atrial fibrillation or flutter was associated with significant improvement in presenting symptoms and functional capacity. A randomized, controlled study is needed to compare this form of therapy with other therapeutic modalities.

Comparison of burst pacing, autodecremental (ramp) pacing, and universal pacing for termination of ventricular tachycardia.

This study was designed to test the comparative efficacy of burst pacing, autodecremental (ramp) pacing, and universal (steep ramp) pacing for termination of ventricular tachycardia. A prospective, randomized sequence cross-over design was used to achieve comparisons of the pacing modalities that were matched for patient, day, and ventricular tachycardia characteristics. Thirty eight patients were enrolled, whose ventricular tachycardia was well-enough tolerated to be reinduced, and tested with 3 pacing modalities. There were 27 series 1 patients in which the pacing modalities were nonsynchronized burst pacing, synchronized burst pacing, and ramp pacing. The 11 patients in series 2 were tested with synchronized burst pacing, ramp pacing, and universal pacing. All pacing methods proved to be comparable in their ability to terminate ventricular tachycardia (p = NS). The 2 burst methods required the fewest number of attempts (significant vs ramp pacing). Universal pacing required the fewest number of stimuli. The mean paced cycle length was similar will all methods. The shortest paced cycle lengths were found with the autodecremental and universal methods because of their ramp patterns. It is concluded that burst, ramp, and universal pacing are of similar efficacy, although ramps were least efficient. Choice of a modality depends on operator preference, and individual patient response.