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Biomedical subjects

J C Luck

Publications and source records attributed to J C Luck.

At least 37 records · Page 2Linked to original sources
PubMed1988

Termination of sustained ventricular tachycardia by external noninvasive pacing.

Cardiac pacing has proven useful in the termination of sustained ventricular tachycardia (VT). In this study, the effectiveness of external noninvasive temporary pacing was compared with traditional endocardial burst ventricular pacing for the termination of sustained and hemodynamically stable VT. In 14 patients, 16 VT morphologies induced by programmed right ventricular extrastimulation were reproducibly terminated by endocardial burst pacing (3 to 9 complexes). VT cycle lengths averaged 392 +/- 97 ms (standard deviation) and ranged from 300 to 690 ms. The endocardial burst pacing cycle length used to terminate VT averaged 298 +/- 93 ms (range 220 to 600 ms). External burst pacing terminated 14 of 16 VT morphologies (88%). The pacing cycle length used to terminate these 14 VTs averaged 282 +/- 44 ms. The number of ventricular captures ranged from 5 to 20 beats. Failure to terminate 2 VT morphologies probably represented a failure of the device to capture the ventricle. Acceleration of VT occurred in 1 patient with burst external noninvasive pacing. These observations suggest that external burst pacing may be an effective means of terminating sustained VT in some patients.

Aged↗
PubMed1988

Clinical suppression of refractory ventricular tachycardia with oral bretylium not predicted by electrophysiologic drug testing.

We report the findings in a patient in whom intravenous bretylium was the only effective agent to suppress refractory ventricular tachycardia and ventricular fibrillation. After attempts to switch the patient to amiodarone and bethanidine (an oral analogue of bretylium) caused proarrhythmic effects, he was successfully converted to oral therapy with bretylium. Electrophysiologic testing was not predictive of the clinical response from oral bretylium. To our knowledge, this is the first report of a proarrhythmic effect from bethanadine and it suggests a divergence in the actions of various class 3 antiarrhythmic agents.

Administration, Oral↗
PubMed1987

Prospective comparison of right and left ventricular stimulation for induction of sustained ventricular tachycardia.

Thirty-eight patients who had sustained monomorphic ventricular tachycardia (VT) or sudden cardiac death underwent programmed ventricular stimulation. To assess the relative efficacy of right and left ventricular (RV and LV) stimulation, a tandem protocol with 1 to 4 extrastimuli and burst pacing was used. Each step of the protocol was performed in a rotating sequence at the RV apex, basal RV septum and LV apex. Sustained VT was induced from the RV apex in 26 patients, right ventricle (either site) in 27, and LV apex in 24, and spontaneous VT was reproduced from those sites in 11, 14 and 12 patients, respectively. In the 23 patients who had sustained VT induced from both ventricles, RV stimulation always required fewer or the same number of extrastimuli for induction. At every stage of the protocol, the cumulative yield of sustained VT was consistently greater from the right ventricle than from the left ventricle. After delivering 4 extrastimuli and burst pacing, LV stimulation only increased the yield of sustained VT by 1 patient, and spontaneous VT by 3 patients. Inducibility or noninducibility in the right ventricle generally predicted the same outcome in the left ventricle. Previously undocumented VT or ventricular fibrillation was induced from the right ventricle in 19 patients and from the left ventricle in 13. Thus, LV stimulation was less efficacious than RV stimulation. LV stimulation increased the yield over RV stimulation only minimally and did not reduce the number of extrastimuli required to induce sustained VT.

Cardiac Catheterization↗
PubMed1987

Two different patterns of entrainment of ventricular tachycardia.

In a patient with two morphologic forms of ventricular tachycardia, rapid pacing from different ventricular sites produced two distinctively different patterns of entrainment. Pacing from sites contralateral to the site of emergence of ventricular tachycardia caused progressive fusion. Following pacing, the interval (return interval) between the first tachycardia beat (return beat) and the preceding beat was equal to the pacing cycle length. Near the site of emergence, the local electrogram of the return beat was morphologically identical to that of the preceding paced beats. In contrast, pacing from sites ipsilateral to the site of emergence did not cause fusion. The return intervals increased with decreasing pacing cycle lengths. The local electrogram of the return beat was morphologically different from that of the preceding paced beats. Using a model of ventricular reentrance, both patterns of responses can be explained. Pacing impulses arising from sites contralateral to the site of emergence activate the latter orthodromically. Fusion occurs between the emerging tachycardia wavefront and the next pacing wavefront. In contrast, pacing impulses arising from sites ipsilateral to the site of emergence activate the latter antidromically. Fusion is not observed because collision within the area of slow conduction prevents the emergence of the tachycardia during pacing.

Adult↗
PubMed1987

Termination of sustained tachycardia by external noninvasive pacing.

Invasive cardiac pacing has proved useful in the induction and termination of reentrant sustained tachycardias. In one of our two cases, programmed ventricular extra-stimulation was used to induce sustained ventricular tachycardia from the endocardial surface of the right ventricle. Induced ventricular tachycardia was terminated by burst ventricular pacing with an external cardiac pacemaker. In our second patient, external pacing was effective at inducing and terminating sustained supraventricular tachycardia. These patients illustrate that the principles of terminating sustained reentrant tachycardia with invasive pacing may also apply to noninvasive external pacing. The usefulness of this approach in treating reentrant tachycardias needs further evaluation.

Adult↗
PubMed1986

Electrophysiologic evaluation of pirmenol for sustained ventricular tachycardia secondary to coronary artery disease.

The efficacy and electrophysiologic effects of pirmenol were evaluated in 21 patients with a history of sustained ventricular tachycardia (VT) and coronary artery disease. Intravenous pirmenol (0.7- to 1.1-mg/kg bolus, followed by a 35- to 40-micrograms/kg/min infusion) significantly prolonged the PR, QRS, QT and corrected QT intervals, HV interval and right ventricular effective refractory period, and shortened the sinus cycle length and atrioventricular nodal block cycle length. All 21 patients had inducible VT (20 sustained, 1 nonsustained) during programmed stimulation in the control state. After intravenous pirmenol, 5 patients (24%) no longer had inducible VT. In those in whom VT was still inducible, the VT cycle length was prolonged significantly. The 5 patients who responded to intravenous pirmenol were given oral pirmenol (200 to 250 mg every 8 hours) for 1 to 3 days and retested with programmed stimulation. In 4 of these 5, VT could not be induced with oral pirmenol administration; in 1 patient sustained VT was induced and pirmenol therapy was discontinued. Oral pirmenol suppressed recurrent VT during a follow-up of 315 +/- 133 days in 4 patients. However, pirmenol therapy was discontinued in 2 patients because of possible deleterious effects (worsened heart failure in 1 patient and elevated liver function test results in 1). Thus, pirmenol, a type IA antiarrhythmic drug, had an overall efficacy of approximately 19% in patients with sustained VT secondary to coronary artery disease.

Adult↗
PubMed1986

Effect of increased current, multiple pacing sites and number of extrastimuli on induction of ventricular tachycardia.

Reproduction of spontaneously occurring ventricular tachycardia (VT) and induction of previously undocumented VT were studied prospectively in 98 patients: 48 with documented sustained VT or ventricular fibrillation, 25 with nonsustained or exercise-induced VT, and 25 with no documented VT. Patients received 1 to 4 ventricular extrastimuli and ventricular burst pacing at 2 right ventricular (RV) sites, first at twice late diastolic threshold, and then at 10 mA using a prospective, tandem study design. Spontaneously occurring VT was reproduced in 37 of 48 patients (77%) at twice late diastolic threshold and in 1 other patient (2%) at 10 mA. VT was reproduced at both RV sites in 17 of 48 patients (35%) and at 1 site in 20 of 48 patients (42%) at twice late diastolic threshold. A previously undocumented VT was induced in 7 of 25 patients (28%) with no documented VT at twice diastolic threshold and 14 of 25 patients (56%) at 10 mA. A previously undocumented VT was induced in 33 of 73 patients (45%) with a history of sustained or nonsustained VT at twice late diastolic threshold and in 47 of 73 patients (64%) at 10 mA. In patients with documented sustained VT, the use of up to 4 ventricular extrastimuli at multiple RV sites increases the sensitivity of the test. In patients without documented VT, the induction of previously undocumented VT with more than 3 ventricular extrastimuli limits the specificity of the test. Increased current provides only a slight advantage over 4 ventricular extrastimuli at twice late diastolic threshold in terms of reproduction of spontaneously occurring VT, but leads to a marked increase in induction of previously undocumented VT.

Aged↗
PubMed1985

Progress in the surgical treatment of cardiac arrhythmias. Initial experience of 90 patients.

Between 1981 and 1985, ninety patients were treated surgically for cardiac arrhythmias and have been followed for a mean interval of 21 months (range, one to 49 months). Follow-up is 100% complete. Fifty accessory pathways were divided in 35 patients (25 male and ten female; mean age, 35.2 years; range, 10 to 72 years), with no deaths. Five females, aged 10 to 35 years, were treated for focal atrial tachycardia, three for an atrial focus alone, and two with other arrhythmia procedures; four were cured and one was improved. Two patients (one man and one woman, both aged 33 years) had ablation of the atrioventricular node. Forty-one patients (32 male and nine female; average age, 56.9 years; range, 15 to 74 years) had ablation of ventricular tachycardia. Kent bundle division and focal atrial tachycardia ablation were also performed in two of these patients. More than 80% of patients had coronary disease. Mean preoperative ejection fraction was 33.9% with a range of 14% to 65%. Aneurysmectomy, endocardial resection, cryoablation, and coronary artery bypass were the procedures used. The perioperative mortality rate was 9.8% but there were no deaths in the last 23 patients. Ventricular tachycardia was abolished in all but three survivors in whom medical treatment is now effective. The automatic implantable defibrillator was implanted in 11 patients, with no surgical deaths. These results confirm the feasibility of relieving a variety of serious arrhythmias by surgical intervention.

Adolescent↗
PubMed1985

Effect of bradycardia on dispersion of ventricular refractoriness.

The effect of bradycardia on dispersion of ventricular refractoriness was evaluated. Refractory periods were measured at 3 right ventricular sites in 16 patients with severe bradycardia (average heart rate 39 +/- 5 beats/min) and were compared with those measured in 11 control subjects, (average heart rate 72 +/- 12 beats/min). Patients with bradycardia had significantly longer effective (377 +/- 36 ms) and functional (421 +/- 39 ms) refractory periods (ERP and FRP) than control subjects (ERP 296 +/- 25 ms, FRP 346 +/- 18 ms) (p less than 0.001). However, dispersion of refractoriness was similar in the 2 groups. Dispersion of ERP was 43 +/- 38 ms and FRP was 48 +/- 35 ms in patients with bradycardia. In control subjects dispersion of ERP was 37 +/- 12 ms, and FRP was 36 +/- 20 ms. Pacing of 120 beats/min significantly decreased ERP and FRP in both groups. Pacing shortened dispersion significantly in control subjects. In patients with bradycardia, pacing failed to significantly decrease dispersion. Compared with control subjects with normal heart rates, patients with bradycardia have longer absolute refractory periods but do not have significantly increased dispersion of refractoriness. Single and double, twice threshold ventricular extrastimuli (S2 and S3) failed to induce ventricular tachycardia in any patient during bradycardia. Bradycardia alone does not appear to be a factor in the induction of ventricular tachyarrhythmias.

Adult↗
PubMed1985

Permanent triggered antitachycardia pacemakers in the management of recurrent sustained ventricular tachycardia.

Permanent pacemakers capable of triggered ventricular stimulation were implanted in 28 patients with a history of sustained ventricular tachycardia or fibrillation. Noninvasive programmed ventricular stimulation was performed on 125 occasions during follow-up periods ranging from 1 to 25 months and was used to assess the efficacy of antiarrhythmic drug therapy, drug or dosage changes and left ventricular endocardial resection. Drug or dosage changes based on noninvasive programmed ventricular stimulation were made in 19 of the 28 patients. In addition, 126 episodes of spontaneous sustained ventricular tachycardia were terminated noninvasively in nine patients. It is concluded that a permanent pacemaker capable of triggered ventricular stimulation is useful in patients with ventricular tachycardia or fibrillation that is difficult to control.

Adult↗
PubMed1985

Importance of pacing site in entrainment of ventricular tachycardia.

Transient entrainment by pacing has been demonstrated during various tachyarrhythmias, including ventricular tachycardia. A patient is described who had two morphologically distinct forms of sustained ventricular tachycardia induced by programmed stimulation. Entrainment of both configurations of ventricular tachycardia was demonstrated. Evidence for entrainment included the presence of different degrees of fusion between paced and ventricular tachycardia complexes at different pacing cycle lengths, and the observation that the last entrained beat was always unfused and identical in configuration to the ventricular tachycardia complexes. Termination of ventricular tachycardia only occurred at pacing cycle lengths at which there was loss of fusion. Catheter endocardial mapping suggested a septal origin of both configurations of ventricular tachycardia. Demonstration of entrainment was dependent on pacing site, being seen only during pacing in the ventricle opposite from that showing earliest activation during ventricular tachycardia. Thus, when attempting to entrain ventricular tachycardia, multiple pacing sites in both ventricles should be used.

Bundle-Branch Block↗
PubMed1985

Emergency defibrillation using a temporary pacing electrode catheter.

Direct application of electrical current to the heart utilizing special equipment such as implantable defibrillators or specially designed catheters has been useful in patients with recurrent ventricular tachyarrhythmias. We describe a patient who developed intractable ventricular fibrillation (VF) during the course of electrophysiologic testing. VF continued for 50 minutes, during which time multiple transthoracic shocks of 360 joules failed to convert the arrhythmia. Intracardiac shocks were then delivered via a transvenous 6 French standard quadripolar pacing catheter positioned in the right ventricular apex by direct application of the defibrillator paddle to the catheter, with the patient lying on the posterior paddle. Energy of up to 300 joules failed to defibrillate the patient, but use of 360 joules delivered in this fashion defibrillated the patient twice. Despite the protracted time of cardiac arrest, the patient recovered without sequelae. We report this case to demonstrate that VF refractory to transthoracic defibrillation may be converted by intracardiac shocks using a temporary pacing catheter without special equipment.

Cardiac Catheterization↗
PubMed1984

Specialized delivery systems for intravenous nitroglycerin. Are they necessary?

Nitroglycerin is absorbed in vitro into polyvinyl chloride tubing, and it has been recommended that nitroglycerin be administered intravenously through specialized polyethylene infusion sets. To determine if tubing type is essential to achieve physiologic effectiveness, we studied dose responses to intravenous nitroglycerin in 15 patients with heart failure using standard polyvinyl chloride tubing in seven (group 2) and special polyethylene infusion sets in seven (group 1) (one patient was excluded from analysis because of technical difficulties). We monitored heart rate, blood pressure, right atrial pressure, pulmonary artery pressure, pulmonary capillary wedge pressure, and cardiac output. Cardiac index, systemic and pulmonary vascular resistance, triple index, rate pressure product, stroke volume, stroke volume index, and stroke work index were calculated. Baseline and treatment measurements were obtained from five to 15 minutes after the infusion of 10, 20, 40, and 80 micrograms of nitroglycerin per minute. Over-all, systolic blood pressure decreased (p less than 0.05) about 8 percent and mean blood pressure approximately 12 percent, mean pulmonary artery pressure and mean pulmonary capillary wedge pressure decreased 30 to 40 percent, and the decline in mean right atrial pressure was 35 percent of baseline (all p less than 0.05). Heart rate and cardiac index did not change (p greater than 0.05). Pulmonary vascular resistance decreased slightly (p = 0.07) and systemic vascular resistance significantly (p less than 0.05). When the two groups were compared physiologic changes were virtually identical (p less than 0.05). Two-way analysis of variance for baseline corrected data proved no differences between tubing sets (p less than 0.05), but the infusion concentration rate was highly related to response (p = 0.0001). A significant (p less than 0.05) decrease in mean blood pressure and mean right atrial pressure was noted at lower dose rates (20 micrograms per minute and 40 micrograms per minute, respectively) in group 1. Beneficial hemodynamic effects in heart failure patients can, then, be predicted to occur at 80 micrograms per minute infusion rates; these responses seem independent of the type of infusion tubing system employed. Additionally, when patients given intravenous nitroglycerin for various reasons were followed for 48 hours, the majority receiving infusions via polyvinyl chloride tubing (group 2) did not require dosage adjustments. Also, at lower flow rates, more solution than calculated may be delivered when polyethylene tubing infusion sets are employed with volumetric infusion pumps.

Blood Pressure↗
PubMed1984

Conduction system abnormalities in symptomatic mitral valve prolapse: an electrophysiologic analysis of 60 patients.

This study examined the site of atrioventricular (AV) block in mitral valve prolapse (MVP). Sixty symptomatic patients with MVP underwent electrophysiologic study; 49 had documented arrhythmias and 28 had syncope. Eight patients had spontaneous second- or third-degree AV block and 10 had chronic bundle branch block. Electrophysiologic study revealed abnormal sinus node function in 8 patients, prolonged HV interval in 10, intra-Hisian delay in 9, and functional bundle branch block in 15. Dual AV nodal pathways were demonstrated in 24 patients. Comparison with 101 similarly symptomatic patients without MVP revealed a greater prevalence of dual AV nodal pathways in the MVP patients. Infranodal conduction abnormalities and dual AV nodal pathways are frequently revealed by electrophysiologic testing in symptomatic patients with MVP.

Adolescent↗
PubMed1984

Electrophysiologic effects of ethmozin in patients with ventricular tachycardia.

Ten patients with recurrent episodes of ventricular tachycardia (VT) had electrophysiologic studies in the basal state and on chronic oral ethmozin (12.1 +/- 0.6 SE mg/kg/day). Ethmozin significantly prolonged the AH interval (basal: 75 +/- 8 SE msec; ethmozin: 91 +/- 10 msec, p less than 0.05), the HV interval (51 +/- 3; 66 +/- 5 msec, p less than 0.01), and the QRS duration (101 +/- 4; 118 +/- 4 msec, p less than 0.001). Atrial and ventricular refractory periods and the corrected QT interval were not significantly affected by ethmozin. VT was induced in 7 of 10 patients in the basal state by means of programmed right ventricular extrastimulation or rapid burst ventricular pacing. On oral ethmozin nine patients had inducible VT. VT cycle length was consistently prolonged on ethmozin (250 +/- 13; 326 +/- 14 msec, p less than 0.001). Four of the seven patients with VT on basal ambulatory monitoring had total abolition of spontaneous VT on ethmozin. Ethmozin failed to prevent induction of VT in most patients despite significant reductions in ventricular arrhythmia on ambulatory monitoring. Further studies comparing VT induction with ambulatory monitoring in patients on ethmozin are needed to confirm these findings and to define the clinical significance of this dissociation.

Adult↗
PubMed1984

Gonococcal endocarditis: a case series demonstrating modern presentation of an old disease.

Gonococcal endocarditis appeared with striking frequency in the preantibiotic era compared with its surprising rarity today. We present a series of four episodes of gonococcal endocarditis, which presented to our institution in the last 2 years, after no cases in the previous decade. Three episodes involved the aortic valve and required emergency aortic valve replacement. One episode involved the tricuspid valve and was successfully cured with antibiotic infusion alone. Combining our four patients with the available 25 well-documented gonococcal endocarditis cases reported in the English medical literature during the antibiotic era, we demonstrated that the disease incidence may be increasing, that infections more often involve left-sided cardiac structures (particularly the aortic valve), and that the association with a quotidian fever curve, rash and arthritis, and overt gonococcal infection is less common than previously reported. These patients frequently present with fulminant and dramatic valvular insufficiency without immediately positive blood cultures and complete echocardiographic evaluation seems to provide a valuable aid in making a presumptive diagnosis of endocarditis and directing appropriate clinical management.

Adult↗