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Biomedical subjects

S Schmaltz

Publications and source records attributed to S Schmaltz.

At least 19 recordsLinked to original sources
PubMed1996

A model to assess the usefulness of performance indicators.

This paper describes the Perception-Action-Impact (PAI) model used for testing the usefulness of health care organization performance indicators, and reports preliminary data in support of this model. Two hundred and ninety six hospitals contributed 500,000 obstetrical cases, and responded to surveys to assess various aspects of indicator usefulness. Domains of interest that were assessed include relevance of the measures, whether the measures identified opportunities for improvement, whether the health care organization took any action in response to the data, health care organizational structure for data use, and methods for dissemination of the indicator data. Findings from this study provide support for the PAI model. Consequently, perceptions regarding the indicators apparently have a significant impact on the usefulness of the data. When action was taken in response to the indicator data, a positive impact on patient care processes and outcomes was the typical result. Additional research is needed in the areas of data dissemination effectiveness, and the impact of attitude change on the use of performance measures.

Analysis of Variance↗
PubMed1994

beta-Hydroxybutyrate decreases adenosine triphosphate degradation products in human subjects.

Many disease states decrease intracellular adenosine triphosphate (ATP) levels and elevate body fluid purine levels. The use of specific metabolic substrates may reverse this process. This study was designed to test the hypothesis that beta-hydroxybutyrate, a substrate for ATP synthesis, decreases body fluid purine levels during interventions that induce ATP degradation. Decreases in these purine levels are metabolic markers for diminished ATP degradation. Two human models for stimulating ATP degradation were used to test the hypothesis. Rapid fructose infusion causes acute degradation of hepatic ATP, and ischemic exercise stimulates ATP consumption in skeletal muscle. The activity of beta-hydroxybutyrate was used in combination with phosphate, another important substrate for ATP synthesis. The studies were performed during a low-phosphate state in 10 normal subjects and during a high-phosphate state in 7 normal subjects. Metabolic variables, such as serum or urinary phosphate level, blood beta-hydroxybutyrate level, blood acetoacetate level, plasma or urinary purine level, blood lactate level, and blood ammonia level, were monitored during the study. After ischemic exercise of the forearm muscle, beta-hydroxybutyrate decreased the level of plasma total purines, blood lactate, and blood ammonia during the low-phosphate state but not during the high-phosphate state. During fructose-induced hepatic ATP breakdown, beta-hydroxybutyrate decreased late phase plasma purine increases under low-phosphate conditions only and decreased urinary total and radiolabeled purine elevations under both phosphate conditions. These data indicate that the infusion of beta-hydroxybutyrate may alter the balance from ATP degradation toward ATP resynthesis in muscle and liver by providing an immediate source of fuel and reducing equivalents under under specific metabolic conditions. This activity in combination with other metabolic interventions may have therapeutic value by restoring ATP pools in ATP-depleted tissues.

3-Hydroxybutyric Acid↗
PubMed1993

Management of nonsustained ventricular tachycardia guided by electrophysiological testing.

Two hundred eighty patients with spontaneous nonsustained ventricular tachycardia were treated based on the results of electrophysiological testing. Seventy-nine patients had no evidence of structural heart disease, 134 had coronary artery disease, 43 had idiopathic dilated cardiomyopathy, and 24 patients had miscellaneous types of heart disease. Sustained monomorphic ventricular tachycardia was induced during electrophysiological testing in the drug free state in 52 of 280 patients (19%). Ventricular tachycardia was induced more frequently in patients with coronary artery disease (32%) than in any of the other groups (P < 0.001). The patients with inducible sustained monomorphic ventricular tachycardia underwent a mean of 1.9 +/- 1.3 drug trials. Twenty-five patients had the induction of ventricular tachycardia suppressed by pharmacological therapy and were treated with the drug judged to be effective during electropharmacological testing. Twenty-seven patients continued to have inducible sustained monomorphic ventricular tachycardia despite antiarrhythmic therapy and were discharged on the drug that made induced ventricular tachycardia best tolerated. Forty-five of 280 patients (16.1%) died during a mean follow-up period of 19.6 +/- 14.4 months. There were 15 sudden cardiac deaths, 21 nonsudden cardiac deaths, 6 noncardiac deaths, and 3 deaths that could not be classified. Sudden cardiac death mortality was lowest in the patients without structural heart disease (0% at 2 years), intermediate in the patients with coronary artery disease and miscellaneous heart disease (4% at 2 years), and highest in the patients with idiopathic dilated cardiomyopathy (13% at 2 years; P < 0.01 for pairwise comparisons). No patient treated with a drug that had suppressed the induction of sustained ventricular tachycardia died suddenly during the follow-up period whereas four of 27 patients who were discharged on "ineffective antiarrhythmic drugs" and 11 of 228 patients without inducible sustained ventricular tachycardia experienced sudden cardiac death during the follow-up period. By multivariate analysis, ejection fraction and inducible ventricular tachycardia during the predischarge electrophysiological test were independent predictors of sudden cardiac death. In conclusion, in patients with spontaneous non-sustained ventricular tachycardia: (1) Arrhythmia inducibility varies depending on the underlying heart disease.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed1992

Reversal of antiarrhythmic drug effects by epinephrine: quinidine versus amiodarone.

Although previous studies have demonstrated that the electrophysiologic effects of many antiarrhythmic agents can be reversed by catecholamines, the susceptibility of amiodarone to such reversal is unknown. The objective of this study was to compare the relative degree of reversal of the electrophysiologic effects of quinidine and amiodarone by epinephrine infusions that result in plasma epinephrine levels similar to those achieved during various physiologic stresses. Twenty-nine patients who had inducible sustained monomorphic ventricular tachycardia and underwent electropharmacologic testing with quinidine and amiodarone were enrolled in the study. The variables measured before and during an epinephrine infusion (25 or 50 ng/kg per min) included the sinus cycle length, mean arterial pressure, QT interval and effective refractory period at drive train cycle lengths of 600 and 400 ms. The effective refractory period measured at a drive train cycle length of 600 ms shortened less during amiodarone therapy (2 +/- 2%) than during quinidine therapy (6 +/- 4%) or than in the baseline state (6 +/- 4%; p less than 0.01). Similar results were obtained during evaluation of the effective refractory period at a cycle length of 400 ms. Epinephrine infusion, at both 25 and 50 ng/kg per min, completely reversed the effects of quinidine and partially reversed the effects of amiodarone on the effective refractory period. The effects of epinephrine on the sinus cycle length and QT interval were similar in the baseline state and in conjunction with quinidine and amiodarone. Twenty-four patients underwent programmed ventricular stimulation during amiodarone therapy alone and in conjunction with either a 25- or a 50-ng/kg per min infusion of epinephrine.(ABSTRACT TRUNCATED AT 250 WORDS)

Amiodarone↗
PubMed1992

Obsessive and compulsive characteristics of alcohol abuse and dependence: quantification by a newly developed questionnaire.

The purpose of the this study was to develop an instrument for measuring the obsessive and compulsive characteristics of drinking-related thought and behavior in subjects who abuse or are dependent on alcohol, and to quantify the extent to which drinking-related thought and behavior in these subjects resemble the obsessions and compulsions seen in obsessive-compulsive disorder (OCD). To achieve these goals, the Yale-Brown Obsessive Compulsive Scale (Y-BOCS) was modified to reflect obsessionality and compulsivity specifically related to heavy drinking rather than to obsessions and compulsions generally. The modified Y-BOCS (Y-BOCS-hd) was administered to 62 subjects satisfying DSM-III-R criteria for alcohol abuse or alcohol dependence and 62 matched normal controls. The data showed that the Y-BOCS-hd is a sensitive and specific instrument for measuring the obsessive and compulsive characteristics of drinking-related thought and behavior in alcohol-abusing and alcohol-dependent populations, and that there are specific and quantifiable similarities between these characteristics and the obsessions and compulsions of OCD. The data also indicated that the Y-BOCS-hd may be a useful screening instrument for the presence of alcohol abuse and dependence.

Adult↗
PubMed1992

Electrogram criteria for identification of appropriate target sites for radiofrequency catheter ablation of accessory atrioventricular connections.

BACKGROUND: Catheter ablation of accessory atrioventricular (AV) connections using radiofrequency current has been demonstrated to be effective in the majority of patients with the Wolff-Parkinson-White syndrome or paroxysmal supraventricular tachycardia involving a concealed accessory AV connection. However, electrogram criteria have not been established to guide attempts at radiofrequency catheter ablation. METHODS AND RESULTS: The characteristics of local electrograms recorded at successful and unsuccessful sites of radiofrequency catheter ablation were determined in 132 patients. Electrograms recorded at a total of 438 sites were analyzed: 338 recorded during ablation of 90 manifest accessory AV connections and 100 recorded during ablation of 44 concealed accessory AV connections. During ablation of manifest accessory AV connections, the independent predictors of outcome were electrogram stability (p less than 0.001), the interval between activation of the ventricular electrogram and onset of the QRS complex (p less than 0.001), and the presence of an accessory AV connection potential (p less than 0.001). Radiofrequency energy delivery at sites demonstrating stable electrograms, a probable or possible accessory AV connection potential, and activation of the local ventrical electrogram before the onset of the QRS complex had a 57% probability of success compared with a 3% probability of success at sites without these features. During ablation of concealed accessory AV connections, the independent predictors of outcome were electrogram stability (p = 0.02), the presence of an accessory AV connection potential (p = 0.05), and the presence of retrograde continuous electrical activity (p = 0.04). Sites demonstrating a stable local electrogram, an accessory AV connection potential, and retrograde continuous electrical activity had an 82% probability of success compared with only a 5% probability of success at sites demonstrating none of these features. CONCLUSIONS: The local electrogram parameters of greatest importance in predicting the success or failure of radiofrequency catheter ablation of accessory AV connections are electrogram stability, the presence of an accessory AV connection potential, and the timing of ventricular activation relative to the QRS complex (for manifest accessory AV connections) or retrograde continuous electrical activity (for concealed accessory AV connections). Awareness of these variables during attempts at radiofrequency catheter ablation of accessory AV connections may minimize the number of unnecessary applications of radiofrequency energy.

Adult↗
PubMed1991

Comparison of the results of electrophysiologic testing after short-term and long-term treatment with amiodarone in patients with ventricular tachycardia.

The results of electrophysiologic testing after short-term and long-term treatment with amiodarone were compared in 71 patients with ventricular tachycardia. Electrophysiologic testing was performed in the baseline state after 11 +/- 3 days of treatment with 1.2 to 2.4 gm/day of amiodarone, and after 13 +/- 4 weeks of therapy with a daily amiodarone dose of 400 mg. After short-term therapy, 62% of the patients had an adequate response to amiodarone. In 27 patients who were hemodynamically unstable, ventricular tachycardia was induced and became noninducible or hemodynamically stable after combination therapy with a class I agent. Among 18 patients who did not have inducible ventricular tachycardia after short-term therapy, eight (44%) had inducible, hemodynamically unstable ventricular tachycardia after long-term treatment with amiodarone. On the other hand, six of the 27 patients who had hemodynamically unstable ventricular tachycardia after short-term therapy had an adequate response after long-term treatment with amiodarone. Therefore an adequate electrophysiologic response after short-term therapy does not guarantee a similar response after long-term treatment, and an inadequate response after short-term therapy does not always predict a similar response after long-term therapy.

Aged↗
PubMed1991

Results of electrophysiologic testing and long-term prognosis in patients with coronary artery disease and aborted sudden death.

The purpose of this study was to evaluate the results of electrophysiologic testing and the long-term prognosis of 56 patients with coronary artery disease who presented with aborted sudden death unrelated to acute myocardial infarction. The mean age of the patients was 62 +/- 8 years (+/- standard deviation) and 48 were men. The mean left ventricular ejection fraction was 0.34 +/- 0.16. During the baseline electrophysiology test, sustained monomorphic ventricular tachycardia (VT) was inducible in 22 patients who then underwent electropharmacologic testing: 11 patients were treated with antiarrhythmic drugs that suppressed the induction of VT or resulted in the VT becoming hemodynamically stable; 10 patients who failed drug testing received an automatic implantable cardioverter/defibrillator (AICD); one patient underwent endocardial resection. Among 34 patients who did not have inducible sustained VT, a precipitant of cardiac arrest (severe ischemia, proarrhythmia) was identified and was corrected in 9 of 34. An AICD was recommended in the remaining 25 patients; however, nine patients refused and were treated empirically with antiarrhythmic drugs. The mean follow-up was 22 +/- 12 months. The 2-year actuarial incidence of sudden death was 31% in patients who were treated with drugs based on the results of electropharmacologic testing, 26% in patients who were treated with antiarrhythmic drugs on an empiric basis, 0% among patients in whom a correctable etiology for the cardiac arrest was identified, and 9% among patients who underwent implantation of an AICD. The 3-year actuarial incidence of sudden death among the 20 patients treated with antiarrhythmic drugs was 53%, compared with 9% among the 26 patients who underwent AICD implantation (p = 0.03).(ABSTRACT TRUNCATED AT 250 WORDS)

Actuarial Analysis↗
PubMed1991

The effect of quinidine and mexiletine on the adaptation of ventricular refractoriness to an increase in rate.

The purpose of this study was to determine the effects of quinidine and mexiletine on the adaptation of ventricular refractoriness to a change in heart rate. The ventricular effective refractory period was measured at a basic drive cycle length of 500 msec with basic drive train durations of two beats, eight beats, 20 beats and 3 minutes. The ventricular refractory periods were measured in the baseline state and after oral treatment with quinidine or mexiletine in 20 subjects each. In the baseline state, there was progressive shortening of the ventricular refractory period as the drive train duration increased from two beats to 3 minutes. Quinidine prolonged refractoriness by 5% (p less than 0.001) at each drive train duration. Mexiletine did not affect the ventricular effective refractory period at any of the drive train durations. In a control group of 20 subjects, there were no significant differences between two determinations of refractoriness at each basic drive train duration. In conclusion, neither quinidine nor mexiletine affect the adaptation of ventricular refractoriness to an increase in rate. Although the ventricular effective refractory period measured with a conventional basic drive train duration of eight beats is often more than 20 msec longer than the actual ventricular effective refractory period measured with a drive train duration of 3 minutes, the effects of quinidine and mexiletine on the conventionally measured ventricular effective refractory period accurately reflect the effects of these drugs on the actual ventricular effective refractory period.

Adaptation, Physiological↗
PubMed1991

Differences in QRS configuration during unipolar pacing from adjacent sites: implications for the spatial resolution of pace-mapping.

To examine the spatial resolution of unipolar pace-mapping, 12 lead electrocardiograms (ECGs) recorded during pacing from each of the poles of a quadripolar catheter (5 mm interelectrode distance) were examined. Unipolar pacing was performed from each of the poles at late diastolic threshold, twice threshold and 10 mA at a cycle length of 500 ms. In 15 patients, pacing was performed at the right ventricular apex and in 14 at various left ventricular sites. Pacing from the distal catheter pole at threshold (index ECG) was used to simulate the site of origin of ventricular tachycardia, and all other ECGs were compared with the index ECG. Electrocardiograms were evaluated by two independent observers for 1) minor configuration differences (notch, new small component, change in the amplitude of individual components or change in QRS shape); 2) major differences in configuration (new large component, marked change in the amplitude of an existing component or two minor changes); and 3) peak to peak changes in amplitude. Minor differences in configuration were seen in a mean 2.4 +/- 1.9, 4.6 +/- 2.4 and 4.4 +/- 2.9 leads during pacing at 5, 10 and 15 mm from the distal electrode (index site). Major differences in configuration were seen in a mean of 0.3 +/- 0.5, 2.1 +/- 2.1 and 3.7 +/- 2.3 leads during pacing at 5, 10 and 15 mm from the index site. Differences in amplitude were seen in a mean of 3.1 +/- 2.2, 5.6 +/- 2.5 and 6.8 +/- 3.0 leads per ECG during pacing at 5, 10 and 15 mm from the index ECG pacing site, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Cardiac Pacing, Artificial↗
PubMed1991

Variability in the measurement of human ventricular refractoriness.

The degree of variability in ventricular refractoriness and factors potentially affecting this variability were evaluated in 80 patients undergoing an electrophysiological study. Each of seven variables (stimulation current, coupling interval of the basic drive train to spontaneous rhythm, pause between determinations, bipolar pacing configuration, bipolar vs unipolar pacing, atrioventricular synchrony, and autonomic tone) was evaluated in a group of ten patients to determine its effects on the reproducibility of refractoriness. Measurements were repeated ten times in every patient under each of two conditions. Five variables had significant effects on the reproducibility of measurements. Pacing at 10 mA was associated with less variability in the determination of ventricular refractoriness than pacing at twice threshold (within-subject variance component 4.5 vs 10.1 msec; P less than 0.001). The mean difference between the longest and shortest determinations of refractory periods (range) was 6.2 msec at 10 mA and 8.6 msec at twice threshold. The use of a conditioning period of pacing and continuous trains (eight beats with a 3-sec pause) rather than a variable pause between serial trials reduced the mean within-subject variance component from 16.5 to 3.3 (P less than 0.001) and the mean range of refractory period determinations from 10.8 to 4.8. The use of the distal rather than the proximal pole as the cathode decreased the mean within-subject variance component from 9.4 to 3.3 (P less than 0.001) and the range of determinations from 6.4 to 5.8 msec. Unipolar pacing was associated with less variability than bipolar pacing (mean within-subject variance component 4.6 vs 6.4; P less than 0.05, mean range 5.0 vs 7.6 msec).(ABSTRACT TRUNCATED AT 250 WORDS)

Cardiac Pacing, Artificial↗
PubMed1991

A comparison of QRS complexes resulting from unipolar and bipolar pacing: implications for pace-mapping.

UNLABELLED: To examine differences in QRS configuration produced by bipolar versus unipolar pacing, 12-lead electrocardiograms recorded during bipolar (distal cathode) pacing with 5- and 10-mm interelectrode distances were compared to electrocardiograms recorded during unipolar cathodal pacing from the distal catheter pole. Pacing was performed at a cycle length of 500 msec using each of the two bipolar configurations at current strengths equal to late diastolic threshold, twice threshold and 10 mA. The pacing site was at the right ventricular apex in 15 patients and at various left ventricular locations in 14 patients. The electrocardiograms recorded during bipolar and unipolar pacing were compared by two independent observers for minor QRS configuration changes, major configuration changes and amplitude changes. Minor configuration differences between unipolar and bipolar pacing occurred occasionally when the interelectrode distance during bipolar pacing was 5 mm (mean +/- S.D. 0.5 +/- 1.2 leads per electrocardiogram). However, when the interelectrode distance was 10 mm, minor configuration differences were seen more commonly (1.3 +/- 2.0 leads per electrocardiogram; P less than 0.05 vs 5-mm distance). Major configuration differences were uncommon with either configuration at all current strengths. Pacing at 10 mA produced a larger number of configuration differences than pacing at either threshold or twice threshold (P less than 0.05). Amplitude differences were seen in a mean of 1.9 +/- 2.1 leads per electrocardiogram with the 5-mm interelectrode distance and a mean of 2.9 +/- 2.1 leads using the 10-mm interelectrode distance (P less than 0.05). IN CONCLUSION: (1) bipolar ventricular pacing can result in QRS complexes that are different from those obtained with unipolar pacing at the same catheter location, presumably due to an anodal contribution during bipolar pacing; (2) increasing the interelectrode distance and stimulus intensity increases these differences; and (3) because the proximal electrode's contribution to depolarization can alter the QRS configuration during pacing in a variable way, the use of bipolar pace-mapping to localize sites of origin of ventricular tachycardia may result in less spatial resolution than unipolar pace-mapping.

Cardiac Catheterization↗
PubMed1991

Prospective comparison of a conventional and an accelerated protocol for programmed ventricular stimulation in patients with coronary artery disease.

BACKGROUND: This study compared the sensitivity, specificity, and efficiency of a "conventional" and "accelerated" programmed stimulation protocol in 293 patients with coronary artery disease who had a history of sustained or nonsustained monomorphic ventricular tachycardia (VT). METHODS AND RESULTS: In the conventional protocol, one and two extrastimuli were introduced during sinus rhythm and during basic drive trains at cycle lengths of 600 and 400 msec at the right ventricular apex and then at the outflow tract or septum. In the accelerated protocol, one, two, and then three extrastimuli were introduced at each of three basic drive train cycle lengths (350, 400, and 600 msec) at the right ventricular apex; the procedure was repeated at a second right ventricular site. Six hundred thirty-four electrophysiological tests were performed using one of these two protocols either in the baseline state (293 tests) or during drug testing (341 tests). The yield of sustained, monomorphic VT was 89% with the conventional protocol and 92% with the accelerated protocol during baseline tests in patients who had a history of sustained VT (p = 0.05); 20% and 34%, respectively, during baseline tests in patients with a history of nonsustained VT (p = 0.06); and 70% and 77%, respectively, during drug testing (p = 0.2). To induce sustained, monomorphic VT, 10.1 +/- 5.0 (mean +/- SD) protocol steps and 14.4 +/- 8.7 minutes were required with the conventional protocol, compared with 4.0 +/- 3.7 steps and 5.6 +/- 6.1 minutes with the accelerated protocol (p less than 0.001 for each comparison). Among the tests in which sustained, monomorphic VT was induced, sustained polymorphic VT or ventricular fibrillation was induced more often with the conventional protocol (3.6%) than with the accelerated protocol (0.9%, p = 0.05). CONCLUSIONS: The efficiency of programmed stimulation can be improved by the early use of a basic drive train cycle length of 350 msec and three extrastimuli. Compared with a conventional stimulation protocol, the accelerated protocol used in this study reduces the number of protocol steps and duration of time required to induce monomorphic VT by an average of more than 50% and improves the specificity of programmed stimulation without impairing the yield of monomorphic VT.

Cardiac Pacing, Artificial↗
PubMed1990

Cost of catheter versus surgical ablation in the Wolff-Parkinson-White syndrome.

In this retrospective study of 22 patients with the Wolff-Parkinson-White (WPW) syndrome, the cost of catheter ablation in 11 patients was compared with that of surgical ablation in another 11 patients. All patients in the catheter ablation group had a posteroseptal accessory pathway; in the surgical group, 5 patients had a left lateral accessory pathway, 3 had a left lateral and posteroseptal accessory connection and 3 had a right-sided pathway. Catheter ablation was successful in 8 of 11 patients (73%). In the surgical group, the accessory pathway was interrupted successfully in all patients (100%). The mean duration (+/- standard deviation) of hospitalization was 6 +/- 2 days in the catheter ablation group and 8 +/- 4 days in the surgical group. The mean cost/patient, expressed in 1988 dollar values, was +14,116 +/- 4,493 in the catheter ablation group and +34,175 +/- 5,434 in the surgical ablation group (p less than 0.0001). The mean time lost from work or school was 10 +/- 5 days in the catheter ablation group and 60 +/- 16 days in the surgical group (p less than 0.01). Catheter ablation is significantly less expensive than surgical ablation of accessory pathways. Assuming that all patients in whom catheter ablation is unsuccessful subsequently undergo successful surgical ablation, the mean cost of definitive therapy in the catheter ablation group (+24,382 +/- 4,741) is still significantly lower than the cost in the surgical group (+34,175; p less than 0.001). An additional economic advantage of catheter ablation is that the mean time lost from work or school is 10 days compared to 60 days with surgical ablation.

Adolescent↗
PubMed1990

Acute changes in pacing threshold and R- or P-wave amplitude during permanent pacemaker implantation.

This study examines the changes in pacing threshold and R- or P-wave amplitude during the first 30 minutes after implantation of tined and screw-in leads. The leads examined were those of 1 manufacturer (Medtronic) and consisted of 3 ventricular pacing leads (model numbers 6957 unipolar screw-in [11 patients], 6961 unipolar tined [12 patients] and 6962 bipolar tined [7 patients]) and 1 atrial lead (model number 6957J unipolar screw-in [10 patients]). After optimal lead position was obtained fluoroscopically in the right ventricular apex or right atrium, the pacing threshold and R- or P-wave amplitudes were measured at 5-minute intervals for 30 minutes. The acute ventricular pacing threshold with the screw-in lead was significantly higher than with the tined lead (0.84 +/- 0.17 vs 0.58 +/- 0.15 volts; p less than 0.001). There was a significant (p less than 0.001) acute decrease in the ventricular pacing threshold with both lead types, with the maximum decrease occurring 5 minutes after lead implantation. There was a significant acute increase in R-wave size with the ventricular screw-in lead that peaked 20 minutes after lead implantation (11.9 +/- 3.0 to 14.7 +/- 4.1 mV; p less than 0.001). The atrial screw-in lead behaved in a manner identical to its counterpart in the ventricle. In conclusion, there are acute changes in the pacing threshold and R- or P-wave amplitude obtained with tined and screw-in pacing leads.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1990

Effect of basic drive cycle length on the yield of ventricular tachycardia during programmed ventricular stimulation.

The yield of sustained, monomorphic ventricular tachycardia (VT) induced by programmed ventricular stimulation was compared, using basic drive trains of 400 ms, 600 ms and sinus rhythm, to identify the most efficient sequence of basic drive trains to use during programmed stimulation. Fifty-five patients with coronary artery disease and inducible sustained monomorphic VT not requiring countershock to terminate underwent 81 electrophysiology tests in which 1 to 3 extrastimuli were introduced during sinus rhythm and after basic drive trains of 600 and 400 ms. In 72 electrophysiology tests, sustained, monomorphic VT was induced at the right ventricular apex. The yield of VT using a drive cycle length of 400 ms was 63 of 72 (88%), compared to 46 of 72 (64%) when the drive cycle length was 600 ms, and 23 of 72 (32%) when the extrastimuli were introduced during sinus rhythm (p less than 0.001 for all pairwise comparisons). In 14 electrophysiology tests in which VT was not induced using a 400 ms basic drive cycle length at the apex, the yield of VT was higher using a 400 ms drive cycle length at a second right ventricular site (12 of 14) than with a 600 ms drive cycle length (3 of 12) or sinus rhythm (4 of 12) at the apex (p less than 0.05). The yield of sustained, monomorphic VT induced by 1 to 3 extrastimuli increases as the basic drive cycle length shortens. Whereas programmed stimulation is conventionally started during sinus rhythm or with a drive cycle length of 600 ms, the present results suggest that starting with a drive cycle length of 400 ms may be more efficient.

Cardiac Pacing, Artificial↗