Transcatheter Electrical Ablation of Accessory Pathways in Children

Supraventricular tachycardia (SVT), the most common sustained symptomatic arrhythmia of childhood, is often supported hy a manifest or concealed accessory pathway. Permanent interruption of the accessory pathway usually requires surgical division. Recent experience with electrical ablation of posterior septal pathways in adults prompted us to apply the technique to children. Six children, ages 8 to 15 years, underwent a complete electrophysiological study followed by transcatheter electrical ablation. Five of the 6 children, 3 with a right posterior septal and 2 with a left posterior septal pathway, were approached with the ablation catheter at the os of the coronary sinus. In the remaining patient, a left lateral pathway was mapped with an electrode catheter in the coronary sinus and then approached with the ablation catheter through the patent foramen into the left atrium. Two patients are asymptomatic 18–24 months postabla-tion; one patient had return of anomalous conduction between 7 and 21 days after ablation. Two patients had transient interruption of anomalous conduction, whereas one patient experienced no effect. We conclude that in carefully selected patients, transcatheter electrical ablation ofers an alternative to surgery for permanent interruption of an accessory pathway. (PACE, Vol. 12, November 3989)Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/71986/1/j.1540-8159.1989.tb01865.x.pd

Effect of Propranolol on Ventricular Rate During Atrial Fibrillation in the Wolff-Parkinson-White Syndrome

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/74695/1/j.1540-8159.1987.tb04511.x.pd

Effects of different packaging methods on microbial, [chemical] and sensory properties of Nile tilapia (Oreochromis niloticus Linnaeus, 1758) fillets during refrigerator storage

The effect of three different packaging methods including Modified Atmosphere Packaging (MAP), Vacuum Packaging and normal Packaging was investigated on the quality of Nile tilapia fresh fillets stored in the refrigerator's temperature. The packaged samples were examined for 10 days with regard to the changes in chemical (TVN, PV, pH), microbial (total viable count) and sensory evaluations. The results indicated that the samples packed in MAP condition had higher quality than that of other methods at the end of the storage period. In addition, the slower destructive impacts and microbial growth was observed in MAP. The results of present study suggest that packaging tilapia under MAP conditions results in the increase in the durability, storing, and distribution period for fillets

Comparison of Ventricular Refractory Periods Determined by Incremental and Decremental Scanning of an Extrastimulus

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/73345/1/j.1540-8159.1989.tb02699.x.pd

An Analysis of Post-Pacing R-R Intervals During Atrial Fibrillation

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/74691/1/j.1540-8159.1986.tb04496.x.pd

Interaction Between Autonomic Tone and the Negative Chronotropic Effect of Adenosine in Humans

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/72287/1/j.1540-8159.1999.tb00412.x.pd

Further Insight into Mechanisms of Ventricular Tachycardia from the Clinical Electrophysiology Laboratory

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/72003/1/j.1540-8167.1991.tb01319.x.pd

Immediate reproducibility of clinical and nonclinical forms of induced ventricular tachycardia

This prospective study assessed the immediate reproducibility of clinical and nonclinical forms of ventricular tachycardia (VT) induced by programmed ventricular stimulation. Twenty-three clinical VTs were unimorphic and previously documented and 22 nonclinical VTs (17 polymorphic and 5 unimorphic) were induced in patients with either no documented or suspected history of VT, or documented VT that had a configuration different from that of the induced VT. The stimulation protocol included 1 to 3 ventricular extrastimuli, 2 drive cycle lengths, and 2 right ventricular stimulation sites. Each VT was induced on the first attempt, then the stimulation protocol was repeated twice in the drug-free state. After the first VT induction, 21 of 23 clinical VTs (91%) and 17 of 22 nonclinical VTs (77%) were reinduced on the second attempt. After 2 VT inductions, 21 of 21 clinical VTs (100%) and 15 of 17 nonclinical VTs (88%) were reinduced on the third attempt. The reinduction rates of the clinical and nonclinical VTs were not significantly different. Among the clinical VTs, the reproducibility of the induction technique was 81% after 1 induction and 88% after 2 inductions with the same technique. These results imply that (1) acute drug testing can be reliably performed after 2 inductions but not 1 induction of clinical VT; (2) reproducibility is not helpful in determining whether an induced VT is clinical or nonclinical; and (3) changes in induction technique during drug testing should be interpreted with caution because changes may occur in the absence of drugs.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/26088/1/0000164.pd

Value of programmed ventricular stimulation in presumed carotid sinus syndrome

This study determines the results of programmed stimulation in patients with syncope or near-syncope presumed to have the carotid sinus syndrome based on the finding of carotid sinus hypersensitivity and the absence of any other apparent cause for syncope or near-syncope after clinical evaluation. Fourteen patients had coronary artery disease, 1 had dilated cardiomyopathy and 18 patients did not have structural heart disease. Programmed simulation was performed at 2 basic drive cycle lengths and 2 right ventricular sites with 1 to 3 extrastimuli. Sustained unimorphic ventricular tachycardia (VT) was induced in 5 of 15 patients who had structural heart disease, and in none of the 18 patients who did not (p 0.05). Patients who had inducible unimorphic VT were treated with antiarrhythmic drugs that suppressed the induction of VT, and 4 of 5 patients also received a pacemaker; no patient had a recurrence of syncope during followup. Patients who had inducible polymorphic VT and VF (n = 10) or no inducible VT (n = 18) received treatment directed at only carotid sinus syndrome. Two patients with inducible VT or VF and 1 patient without inducible VT had recurrent syncope during follow-up, but none had cardiac arrest or died suddenly. It is concluded that programmed stimulation should be performed in patients presumed to have carotid sinus syndrome who have structural heart disease; unimorphic VT may be induced in one-third of these patients, raising the possibility that VT is the cause of syncope. Antiarrhythmic drug therapy may be unnecessary if polymorphic VT or VF is induced. In patients without heart disease, programmed stimulation is highly unlikely to yield a clinically significant arrhythmia.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/26529/1/0000068.pd

The interplay between endogenous catecholamines and induced ventricular tachycardia during electrophysiologic testing

Plasma epinephrine and norepinephrine concentrations were measured before, during, and shortly after induced ventricular tachycardia (VT) in 22 selected patients. Sustained, unimorphic VT was induced by programmed ventricular stimulation and terminated after 45 to 384 seconds by overdrive pacing in all patients. In no patient did VT result in loss of consciousness. The baseline plasma catecholamine concentrations did not correlate with the baseline right ventricular effective refractory period, the cycle length of induced VT, or the number of extrastimuli required to induced VT. Induced VT was not associated with a significant increase in the mean plasma epinephrine concentration. In contrast, the plasma norepinephrine concentration increased from a mean baseline level of 317 +/- 136 pg/ml (mean +/- standard deviation) to 418 +/- 220 pg/ml during VT (p = 0.01) and increased further to 569 +/- 387 pg/ml shortly after VT (p p < 0.05 for each). In eight patients the same configuration of VT was induced on two sequential attempts; in five patients the same number of extrastimull were required for the second induction of VT as for the first, whereas in three patients fewer extrastiuli were required. Plasma cateholamine concentrations were not higher in patients requiring fewer extrastimuli to induce the second episode of VT, either shortly after the first episode of VT or shortly after the second episode of VT. In conclusion, plasma catecholamines do not influence baseline ventricular refractoriness, the cycle length of induced VT, or the VT induction technique. Induced VT, which does not require termination by direct-current countershock, is generally associated with little or no increase in plasma epinephrine and a variable increase in plasma norepinephrine concentration, depending on the severity and duration of hypotension during VT. The plasma catecholamine response to VT does not affect a second induction of VT. Therefore, endogenous catecholamines exert little influence on the results of electrophysiologic testing in patients with sustained VT which does not require termination by direct-current countershock.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/26830/1/0000389.pd