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Biomedical subjects

G S Wolff

Publications and source records attributed to G S Wolff.

At least 19 recordsLinked to original sources
PubMed2000

Initial low temperature setting in radiofrequency catheter ablation of Wolff-Parkinson-White syndrome.

Previous studies have shown that with low temperature testing for RF ablation of arrhythmias, unnecessary irreversible myocardial lesions may be avoided. In children admitted for RF ablation from June 1996 to May 1999, we evaluated the method of an initial temperature setting of 50 degrees C for a maximum of 10 seconds. If accessory pathway block occurred, the temperature setting was immediately increased to 70 degrees C and continued for 45-120 seconds (group 1). If accessory pathway block did not occur after several attempts, subsequent attempts were made with initial settings at 70 degrees C-80 degrees C at the same or different sites (group 2). Eighty patients with Wolff-Parkinson-White syndrome (mean age 11 +/- 4 years) were treated using this method. Twelve patients were excluded for various reasons. Of the remaining 68 patients, 52 (76%) had successful block of the pathway at 50 degrees C; 16 patients demonstrated block only at the higher temperature setting of 70 degrees C-80 degrees C. There were no statistically significant differences between these two groups in terms of age, weight, and location of accessory pathways. Unsuccessful 50 degrees C test ablation attempts were 1.6 +/- 2.4 in group 1 and 3.1 +/- 2.9 in group 2 (P = 0.04). Total unsuccessful attempts were 1.6 +/- 2.4 in group 1 and 8.1 +/- 7.1 in group 2 (P = 0.001). The time from application of RF energy to the time of AP block in group 1 was not significantly different from group 2. In the majority of children, successful RF ablation can be achieved by using a temperature setting of 50 degrees C, then 70 degrees C. This will prevent unnecessary permanent injury at unsuccessful attempt sites.

Adolescent↗
PubMed1999

Sodium channel abnormalities are infrequent in patients with long QT syndrome: identification of two novel SCN5A mutations.

Long QT syndrome (LQTS) is a heterogeneous disorder caused by mutations of at least five different loci. Three of these, LQT1, LQT2, and LQT5, encode potassium channel subunits. LQT3 encodes the cardiac-specific sodium channel, SCN5A. Previously reported LQTS-associated mutations of SCN5A include a recurring three amino acid deletion (DeltaKPQ1505-1507) in four different families, and four different missense mutations. We have examined the SCN5A gene in 88 index cases with LQTS, including four with Jervell and Lange-Nielsen syndrome and the remainder with Romano-Ward syndrome. Screening portions of DIII-DIV, where mutations have previously been found, showed that none of these patients has the three amino acid deletion, DeltaKPQ1505-1507, or the other four known mutations. We identified a novel missense mutation, T1645M, in the DIV; S4 voltage sensor immediately adjacent to the previously reported mutation R1644H. We also examined all of the additional pore-forming regions and voltage-sensing regions and discovered another novel mutation, T1304M, at the voltage-sensing region DIII; S4. Neither T1645M nor T1304M were seen in a panel of unaffected control individuals. Five of six T1304M gene carriers were symptomatic. In contrast to previous studies, QT(onset-c) was not a sensitive indicator of SCN5A-associated LQTS, at least in this family. These data suggest that mutations of SCN5A are responsible for only a small proportion of LQTS cases.

Adolescent↗
PubMed1999

Controlled ventilation enhances catheter stability during radiofrequency ablation.

Variations in the amplitude of the atrial and ventricular depolarization waves of the intracardiac electrogram occur during different phases of respiration. Therefore, we tested whether controlled ventilation would reduce ablation attempts and increase the rate of success in patients undergoing radiofrequency ablation with general anesthesia. Thirty-eight children were divided into two groups: (1) controlled and (2) noncontrolled or cyclic ventilation. In the controlled ventilation group, the mapping electrogram was recorded during sustained inspiration, sustained expiration, and cyclic ventilation. Ablation was done in the phase of ventilation that had the least variability in atrial and ventricular amplitudes. Seventeen patients in the controlled ventilation group had tracings adequate for review. In eight patients, ablation was done during sustained inspiration with the percentage change of atrial and ventricular amplitudes (15% +/- 16% and 13% +/- 16%, respectively) being < that during sustained expiration (38% +/- 27%, P = 0.04 and 20% +/- 21%) or during cyclic ventilation (57% +/- 27%, P < 0.01 and 54% +/- 26%, P = 0.003). In nine patients, ablation was done during sustained expiration with the percentage change of atrial and ventricular amplitudes (5% +/- 5% and 5% +/- 2%) being less than that during sustained inspiration (21% +/- 14%, P = 0.01 and 11% +/- 6%, P = 0.01) or during cyclic ventilation (68% +/- 23%, P < 0.001 and 48 +/- 26%, P = 0.001). We achieved success with each patient in both groups, but the number of ablation attempts were less in the controlled ventilation group 1 (3 +/- 2), as compared to the cyclic ventilation group 2 (8 +/- 8; P < 0.02). We concluded that controlled ventilation reduced the number of ablation attempts and facilitated the ablation procedure.

Adolescent↗
PubMed1999

Paired ventricular pacing: an alternative therapy for postoperative junctional ectopic tachycardia in congenital heart disease.

Junctional ectopic tachycardia (JET) is one of the most life-threatening postoperative arrhythmias in children with congenital heart disease, and medical management is difficult. Paired ventricular pacing (PVP) may provide a safe alternative mode of management. We evaluated the safety and efficacy of PVP for the management of postoperative JET in patients with congenital heart disease. A retrospective collection of data was done from 1981-1995. PVP was successfully tried in five postoperative patients (age range: 37 days to 22 years, median: 10 months). Onset of JET was 3-60 hours (mean +/- SD, 19 +/- 23 hours) postoperatively. The maximal JET rate was 261 +/- 39 beats/min. PVP was used as the first line of management in three patients and was successful in all patients. It resulted in an instantaneous increase in blood pressure from 66 +/- 9 to 94 +/- 15 mmHg (42% increase) and was required for 12 +/- 14 hours (range 2-36 hours). No complications were noted. Therefore, in our experience, this is a safe alternative modality for the control of postoperative JET.

Adult↗
PubMed1998

Effects of blocked atrial beats on the atrioventricular nodal recovery property: facilitation or depression?

INTRODUCTION: Blocked atrial beats (A(B)) usually have concealed AV nodal penetration, which can change the nodal conduction time (AH) of a subsequent beat. However, without an output marker it is difficult to assess their effect on the node. In this report we used all possible parameters as nodal resting time after A(B) and plotted them against the AH of testing beats to study their effects on the node. METHODS AND RESULTS: Atrial extrastimulation studies were done in 21 patients in whom one blocked atrial beat (A(2B)) was observed. Nodal recovery curves were obtained for basic pacing (A1), after a conducted premature beat (A2), and after A(2B). In six patients there were 2 to 3 consecutively blocked beats (A(nB)) and recovery curves were constructed after each A(nB). Nodal recovery curves were plotted with AH of the testing beat against different nodal resting parameters and fitted to a single exponential equation. We found contradicting phenomena when using different formats. (1) For recovery curves of A(2B), there was a rightward shift from that of the basic curve when using H1A3 or A1A3 as the gauge (depression phenomenon). On the contrary, there was a leftward shift of the curves when using A(2B)A3 (facilitating phenomenon). (2) For recovery curves after multiple blocked beats there was a marked rightward shift of all curves except A(n-1)(B)An-curves, which were all leftward shifted. CONCLUSION: Because these contradicting phenomena were dictated by the presenting formats, the terms "depression" and "facilitation" cannot be considered intrinsic AV nodal properties outside of the strict context of the pacing protocol and the format of data presentation.

Adolescent↗
PubMed1997

Developmental changes of atrioventricular nodal recovery properties.

Atrioventricular (AV) nodal recovery properties can be studied by a periodic premature stimulation protocol performed at a slow basic rate. Developmental aspects of these properties have not been determined. The purpose of this study was to determine the developmental changes of AV nodal recovery properties. Forty-three children and young adults (male:female ratio 25:18) without AV nodal disease (aged 3.3 to 21.9 years) were studied by delivering premature atrial extrastimuli coupled to basic driven atrial beats. The individual recovery curve was fitted to the equation: A2H2 = A0H0 + exp(alpha -H1A2/tau) for H1A2 > or =theta, where A0H0 is the minimum AH interval, H1A2 is any recovery interval that exceeds the nodal effective refractory period, A2H2 is the corresponding nodal conduction time at any given H1A2, alpha is a constant, tau is the recovery time constant, and theta is the nodal effective refractory period. We found that: (1) A0H0 and alpha constant did not change significantly with age; (2) both tau (r = 0.324; p <0.05) and theta (r = 0.401; p <0.05) had a positive correlation with age; and (3) the maximum change in A2H2 with a 10-ms decrement in H1A2 was 32 ms and did not change significantly with age. Our results suggest that AV nodal recovery properties are age-dependent and both the recovery time constant and effective refractory period lengthen with age.

Adolescent↗
PubMed1997

Similar time-dependent recovery property of fast and slow atrioventricular nodal pathways.

The purpose of this study was to determine whether fast and slow atrioventricular (AV) nodal pathways have the same recovery property. AV nodal recovery property is studied by delivering atrial extrastimuli coupled to atrial beats and plotting nodal coupling intervals against nodal conduction time. In patients with dual pathways the resultant curves will include a fast to fast (F-F) and a fast to slow (F-S) pathway coupled curves. Although fast pathway recovery property can be represented by the former, slow pathway recovery property requires further assessment by studying slow to slow (S-S) pathways coupled curve. In 9 patients with dual pathways F-F, F-S, S-F, and S-S curves were obtained by pacing protocols. In 8 patients (control) without dual pathways, F-F curve and atrial extrastimuli coupled to a preceding slowly conducted fast pathway beat (also designated as S-F curve) were obtained. (1) The S-S curve had a similar time constant as the F-F curve. (2) Although the S-S curve was markedly shifted upward and leftward from the F-F curve, the degree of leftward and upward shifts of the S-S curve from the F-F curve were both close to the difference of the basic fast and slow pathway conduction time (a constant). (3) Although the effective refractory period of the fast pathway in dual pathway patients was longer than that of the control patients, the slow pathway effective refractory period when corrected was close to that of fast pathway in control patients. These results suggest that the fast and slow AV nodal pathways have a similar time-dependent recovery property.

Adolescent↗
PubMed1997

Unexplained syncope: clinical management.

The management of unexplained syncope begins with the patient's history and physical examination, which are oriented to help separate benign from serious causes. Malignant etiologies are more likely to occur with exertional syncope. Cardiac causes should be considered, particularly cardiomyopathy, postoperative congenital heart disease, right ventricular dysplasia, anomalous coronary artery, pulmonary artery hypertension, myocarditis, long QT syndrome, and Wolff-Parkinson-White syndrome. Neurological and metabolic disorders may underlie a syncope episode. After malignant causes of syncope have been excluded and the diagnosis of neurocardiac syncope has been established, treatment strategies include behavior modification, salt and increased fluids, and pharmacological agents. Efficacious agents include beta-blockers, dysopyramide, fludrocortisones, and alpha agents. Yet, behavior modification alone may be as effective as salt or pharmacological therapy. Because the natural history of neurocardiac syncope in children is spontaneous resolution, it is appropriate to try the simple measures before introducing drug therapy.

Adrenergic alpha-Agonists↗
PubMed1996

Usefulness of tilt table test with normal saline infusion in management of neurocardiac syncope in children.

Head-up tilt test has been useful in evaluating children with neurocardiac syncope. In this study patients with positive baseline and isoproterenol tests had repeat tilt testing done after normal saline infusion. If the symptoms persisted, the test was then repeated with phenylephrine infusion. Of the 101 patients studied, 58 (57%) had a positive tilt sign. Normal saline infusion was given to 53 patients. Three patients were excluded because of structural heart disease. Fifty patients (aged 14 +/- 4 years) comprised the study group. Forty-two (84%) of 50 patients had a negative repeat tilt sign after normal saline infusion, and these patients were treated with 0.5 to 1 gm of salt three times a day and/or fludrocortisone (20 patients). Of the 8 (16%) patients who did not respond to normal saline infusion, 5 had negative results when given phenylephrine and were treated with pseudoephedrine. Follow-up data on 42 patients (range 4 to 40 months, median 18 months) showed that all 35 patients who responded to normal saline were either asymptomatic or had improved. Two patients were successfully treated with pseudoephedrine; however, two patients in this group required pacemaker therapy. We conclude that (1) normal saline infusion mitigates the hemodynamic effects of neurocardiac syncope, (2) high-salt diet treatment in these patients was economical and effective, and (3) failure to respond to normal saline test may indicate a less favorable prognosis.

Adolescent↗
PubMed1990

Ventricular arrhythmias in postoperative tetralogy of Fallot.

Ventricular arrhythmias in patients after total surgical repair of tetralogy of Fallot have been associated with late sudden death. In this large multicenter retrospective study of 359 patients with postoperative tetralogy of Fallot, spontaneous ventricular premature complexes (VPCs) on 24-hour ambulatory electrocardiographic monitoring and laboratory-induced ventricular tachycardia (VT) by electrophysiologic stimulation were analyzed. The mean age at surgical repair was 5 years and the mean follow-up duration after repair was 7 years. Spontaneous VPCs on ambulatory monitoring were found in 48% and induced VT on electrophysiologic stimulation was found in 17% of patients. Both spontaneous VPCs and induced VT were significantly related to delayed age at repair, longer follow-up interval, symptoms of syncope or presyncope and right ventricular systolic hypertension (greater than 60 mm Hg) (p less than 0.05), but not to right ventricular diastolic pressure greater than 8 mm Hg. The VPCs on ambulatory monitoring were more complex with increasing age at repair and follow-up duration. Induction of VT on electrophysiologic stimulation correlated with spontaneous VPCs including VT on 24-hour ambulatory electrocardiographic monitoring. The electrophysiologic stimulation protocol varied and the induction of VT increased with a more aggressive stimulation protocol. While induced sustained monomorphic VT was related to all forms of spontaneous VPCs, induced nonsustained polymorphic VT was related to more complex forms of VPCs on ambulatory monitoring. VT was not induced in asymptomatic patients who had normal 24-hour ambulatory electrocardiographic monitoring and normal right ventricular systolic pressure. (ABSTRACT TRUNCATED AT 250 WORDS)

Age Factors↗
PubMed1990

Cardiomyopathy and the use of implanted cardio-defibrillators in children.

Children and adults with cardiomyopathy and ventricular dysrhythmias have a uniformly poor prognosis, despite medical therapy. The use of automatic implantable cardio-defibrillators in adult patients with medically resistant ventricular dysrhythmias has resulted in a positive impact on survival. Because of its size and former lack of programmability, the device has been used rarely in children. Four patients with cardiomyopathy, in whom refractory ventricular dysrhythmias were managed with automatic implantable cardio-defibrillators, are presented. Two of these children are the youngest and smallest known in whom the device has been used; one of them received the first programmable model. The use of the automatic implantable cardio-defibrillator may enhance survival in selected young patients.

Adolescent↗
PubMed1987

Reverse alternating Wenckebach periodicity.

An atrial pacing-induced reverse conduction pattern of the alternating Wenckebach periodicity was observed in 5 of 42 children (12%) during electrophysiologic study. This conduction pattern is a reverse of the usual alternating Wenckebach periodicity: During an underlying 2:1 atrioventricular conduction block there is progressive shortening of the conduction time of the conducted impulses with termination in a lower degree of block. This reverse alternating Wenckebach periodicity may be caused by a mechanism similar to that in other Wenckebach phenomena.

Atrioventricular Node↗
PubMed1986

Electrophysiologic cardiac function before and after surgery in children with atrioventricular canal.

Thirty-two children with atrioventricular (AV) canal underwent electrophysiologic studies: 18 underwent preoperative studies at a median age of 3 years (range 6 months to 16 years); 14 underwent postoperative studies at a median age of 4 years (range 2 to 19); and 2 underwent both preoperative and postoperative matched studies. In the preoperative group the following abnormalities were observed: first-degree AV block in 5 patients (due to internodal conduction delay in 1, AV nodal conduction delay in 2 and normal intracardiac intervals in 2); internodal conduction delay but normal PR interval in 4; and disease of the sinus node in only 1. In the postoperative group the following abnormalities were observed: first-degree AV block in 9 (due to AV nodal conduction delay in 2, His-Purkinje system conduction delay in 1, upper normal intracardiac intervals in 3 and unidentified in 3); prolongation of the right ventricular apical activation time in 11 of 13 with right bundle branch block; abnormal sinus node function in 3; and abnormal AV nodal function in 4 (1 of whom had associated sinus node disease). Atrial and ventricular functions were normal in all preoperative and postoperative patients. Electrophysiologic dysfunction is rare in preoperative patients with AV canal; in postoperative patients electrophysiologic abnormalities occur in 38% and involve the sinus and AV nodes in 19 and 25%, respectively.

Adolescent↗
PubMed1986

Application of the Rosenblueth hypothesis to assess atrioventricular nodal behavior.

Based on the Rosenblueth hypothesis, atrioventricular nodal behavior is evaluated using a method involving the coupling interval at the level of the atrioventricular nodal step delay. If the sum of the coupling interval at the level of step delay and the resultant step delay is greater than the atrial coupling interval, Wenckebach periodicity results; if the sum is less than the atrial coupling interval, the reverse Wenckebach phenomenon occurs; and if both are equal, steady state conduction is reached.

Atrioventricular Node↗
PubMed1986

Atrial pacing-induced alternating Wenckebach periodicity and multilevel conduction block in children.

Multilevel block within the atrioventricular (AV) node has not been previously described in children. Six children with atrial pacing-induced repetitive block are presented. The conduction patterns satisfy the requisites for alternating Wenckebach periodicity or multilevel AV block. In 2 patients the block is documented in the AV node and infra-His region. In 4 patients multilevel block within the AV node is postulated by deductive reasoning. In this study, 2 patterns of alternating Wenckebach periodicity are reported for the first time: sequences of 3:1 block with progressive prolongation of the conducted impulses terminating in 4:1 block; and sequences of 2:1 block with progressive prolongation of the conducted impulses terminating in 2 series of 3:1 block, in which the first conducted impulse following the first 2 blocked beats is not the shortest one, whereas that following the second 2 blocked beats is the shortest.

Atrioventricular Node↗