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M Schulzer

Publications and source records attributed to M Schulzer.

At least 55 records · Page 3Linked to original sources
PubMed1998

Striatal D2 receptors in symptomatic and asymptomatic carriers of dopa-responsive dystonia measured with [11C]-raclopride and positron-emission tomography.

We tested the hypothesis that asymptomatic carriers of dopa-responsive dystonia (DRD) have increased dopamine D2 receptors in the striatum that protect them from the clinical manifestations of dopaminergic deficiency. We examined striatal D2-receptor binding in (1) symptomatic subjects (treated and untreated) and (2) asymptomatic gene carriers. Using [11C]-raclopride PET, we found elevated striatal D2-receptor binding in both groups. In one of our drug-naive symptomatic subjects, 7 months of treatment with levodopa/carbidopa did not affect the receptor binding as measured on a second scan. We conclude that increased D2-receptor binding in DRD may be a homeostatic response to the dopaminergic deficit in subjects carrying the DRD gene, but is not the sole factor determining the clinical state of these individuals.

Adult↗
PubMed1998

Reproducibility of the distribution of carbon-11-SCH 23390, a dopamine D1 receptor tracer, in normal subjects.

UNLABELLED: The reproducibility of [11C]SCH 23390 in PET was studied in 10 normal human subjects. METHODS: The scan-to-scan variation of several measures used in PET data analysis, including the radioactivity ratio, plasma-input Logan total distribution volume (DV), plasma-input Logan DV ratio (DVR) and tissue-input Logan Bmax/Kd values, was determined. RESULTS: There were significant correlations among the radioactivity ratio, plasma-input DVR and tissue-input Bmax/Kd. With the cerebellum as the reference region, these three measures also had high reliability (86%-95%), high between-subject s.d. (7.7%-11.3%) and small within-subject s.d. (2.3%-3.6%), indicating that they are comparable and useful measures for the assessment of dopamine D1 receptor binding. CONCLUSION: The radioactivity ratio and the tissue-input Bmax/Kd may be preferred methods for the evaluation of dopamine D1 receptor binding because these two methods do not require arterial blood sampling and metabolite analysis. Our results show that cerebellum is a reliable reference region for SCH 23390. When the Logan plasma-input function method is used in data analysis for SCH 23390, DVRs rather than total DV values should be used because of the poor reliability of the DV values and their lack of correlation with other measures. Carbon-11-SCH 23390 is thus a reliable and reproducible ligand for the study of dopamine D1 receptor binding by PET.

Benzazepines↗
PubMed1998

Quantitative comparison of three- and two-dimensional PET with human brain studies.

UNLABELLED: The aim of this study was to test the quantitation accuracy of three-dimensional PET in brain scanning. METHODS: Three-dimensional data from 11 human subjects were tested using 11C-dihydrotetrabenazine, 11C-Schering 23390 and 18F-FDG as tracers. Two-dimensional scans were performed on the same subjects and the distribution volume, distribution volume ratio and local metabolic rate of glucose (LMRGlu) values obtained from these were used as reference. Three-dimensional data were processed as follows: iterative convolution subtraction scatter correction, detector normalization including radial and axial geometric factors, attenuation correction extracted from a two-dimensional transmission scan, Kinahan-Rogers reconstruction and region-of-interest-based sensitivity calibration. RESULTS: No major systematic differences between the two methods were found. The agreement between the two-dimensional and three-dimensional data was within 5%. Although statistical analysis generally did not show this difference to be significant, reliability analysis indicated that comparing two-dimensional and three-dimensional data might introduce some inaccuracies. CONCLUSION: Three-dimensional PET yields quantitatively valid results for brain scanning.

Adult↗
PubMed1997

Which clinical sign of Parkinson's disease best reflects the nigrostriatal lesion?

Clinical scales, based on the major signs of Parkinson's disease (PD), are commonly used to assess the effect of symptomatic treatment of PD. With the appearance of therapy aiming to rescue or protect the nigrostriatal neurons in PD, it becomes essential to define which of these signs best reflects the underlying neuronal deficit. Fluorodopa positron emission tomography has been shown to correlate with postmortem nigral cell counts. We correlated the major signs of PD with positron emission tomography results in 35 PD patients. We found that in the "practically defined off" state, (1) Purdue pegboard scores correlated best with the nigrostriatal dopaminergic deficit; (2) of the subscales of the modified Columbia score, the bradykinesia subscale correlated best; (3) rigidity and postural disturbance correlated less highly than bradykinesia, and their inclusion in a multiple regression did not improve the correlation of pegboard or bradykinesia scores alone; and (4) tremor did not correlate with the nigrostriatal dopaminergic deficit. We conclude that pegboard and bradykinesia scores represent the best clinical measures for studying the effect of treatment on the evolution of the nigrostriatal lesion of PD. Inclusion of other clinical signs provides additional information only for the study of functional impairments.

Aged↗
PubMed1997

Regional HmPAO SPECT and CT measurements in the diagnosis of Alzheimer's disease.

BACKGROUND: This study investigated the hypothesis that the combination of regional CT brain atrophy measurements and semiquantitative SPECT regional blood flow ratios could produce a diagnostic test for Alzheimer's disease (AD) with an accuracy comparable to that achieved with the present clinical gold standard of the NINCDS-ADRDA criteria. METHODS: Single proton emission computed tomography (SPECT) and CT head scans were performed on 122 subjects referred an UBC Alzheimer clinic and diagnosed as either 'not demented' (ND-37) or 'possible/probable AD' (AD-85) by the NINCDS-ADRDA criteria. Stepwise discriminant analysis (SDA) was performed on the bilateral SPECT regions of interest and compared to bilateral CT qualitative/quantitative assessment in the frontal, parietal and temporal lobes to determine which were most accurate at ND/AD distinction. Receiver operating curves (ROC) were then constructed for these variables individually and for their combined discriminant function. RESULTS: The left temporal qualitative cortical atrophy score (CT) and left temporal perfusion ratio (SPECT) were selected in the SDA. The combined discriminant function was more specific at AD/ND distinction than either of CT or SPECT alone. The accuracy of AD/ND distinction with the combined discriminant function was below that achieved by clinical diagnosis according to the NINCDS-ADRDA criteria and was not significantly different from that achieved with SPECT or CT alone as defined by ROC curve analysis. CONCLUSION: The measurements of left temporal cortical atrophy and regional cerebral blood flow were most indicative of AD; however they lacked the sensitivity and specificity to recommend their use as a diagnostic test for AD.

Aged↗
PubMed1997

"Familial Parkinson's disease"--a case-control study of families.

BACKGROUND: Parkinson's disease (PD) patients frequently report a family history of PD and this may provide etiological clues to PD. It has also been suggested that a report of a negative family history is reliable. We studied the prevalence of PD in relatives of PD patients to assess the reliability of family history and to evaluate possible explanations of "familial PD" (fPD). METHODS: 81 of 650 (12.5%) PD probands (all PD patients seen at clinic in 4 years) reported a positive family history of PD. Each fPD proband was matched with non-familial PD (nfPD) proband by gender and year of birth. Screening and follow-up questionnaires were mailed to relatives to obtain information concerning pedigree and presence of neurodegenerative disease. Available family members (regardless of disease status) were examined. RESULTS: On examination, 8 persons, said to be "normal" by probands, relatives and themselves, had definite or possible PD (5 fPD, 3 nfPD). The prevalence rate of PD among first and second degree living relatives of probands varied significantly between fPD and nfPD groups (6269/100,000 versus 1190/100,000; p < 0.001). The weighted prevalence (taking into account the proportions of fPD and nfPD within the clinic) was 1822/100,000, a value more than 5 times higher than reported prevalence rates of PD in the general population (p < 0.001). The prevalence rate was greater in first degree relatives than second degree. CONCLUSIONS: "Familial parkinsonism" cannot be explained merely by size of or advanced age within families. Significant numbers of previously unrecognized PD patients may be identified despite a "negative" family history. That is, the patient's report of an absence of familial parkinsonism is frequently inaccurate. The prevalence rate in relatives of PD patients appears to be higher than the general population-regardless of the family history reported by a PD patient. We believe our study suggests that genetic influences or early life environmental exposures are likely to be of etiological importance in PD.

Adult↗
PubMed1997

Intestinal absorption of trace amounts of aluminium in rats studied with 26aluminium and accelerator mass spectrometry.

1. Until recently studies of intestinal aluminium absorption used pharmacological amounts of stable 27Al. 2. To examine the intestinal absorption of trace amounts of different chemical compounds of aluminium, in the present study we have employed the long half-life isotope of aluminium, 26Al, and accelerator mass spectrometry. Trace amounts of 26Al (2.7-12.1 ng) as the hydroxide, citrate, citrate plus 1 mmol/kg sodium citrate, or maltolate respectively, were administered to four groups of rats (n = 9 per group) by gavage. Blood and urine samples were collected for 5 h and the 26Al content (as a percentage of the administered dose) determined by accelerator mass spectrometry. 3. The 5 h urinary 26Al excretion amounted to 0.1 +/- 0.02, 0.7 +/- 0.2, 5.1 +/- 1.5 and 0.1 +/- 0.1% of administered dose in the four groups respectively. There was a strong positive correlation between peak plasma 26Al (r = 0.98) and urinary 26Al excretion in individual animals (P < 0.001). 4. We conclude that the fractional intestinal absorption of trace oral doses of aluminium hydroxide is at least 0.1% (compared with the previous estimate of 0.01% using large 27Al oral loads). Absorption of aluminium citrate given alone is significantly greater (0.7%) and is further increased to 5% by the accompanying sodium citrate, consistent with an enhancing effect of added citrate upon mucosal aluminium permeability. Aluminium maltolate absorption approximates that of aluminium hydroxide (0.1%).

Aluminum↗
PubMed1997

Efficacy, stability and predictors of outcome of pallidotomy for Parkinson's disease. Six-month follow-up with additional 1-year observations.

We tested the efficacy, stability and predictors of outcome of unilateral pallidotomy used to treat patients with Parkinson's disease inadequately controlled with pharmacotherapy (IP). The surgical procedure was as simple as possible; we used CT rather than MRI, and we omitted microelectrode recording. We studied 24 patients with IP; 22 of these patients had drug-induced dyskinesias. There was a significant and stable improvement in all the major parkinsonian motor signs in the OFF (medication) state on the contralateral side. In the ON (medication) state peak-dose dyskinesias were alleviated on the contralateral side. The only significant and stable change on the ipsilateral side was improvement in dyskinesias less marked than on the contralateral side. The improvement in Unified Parkinson's Disease Rating Scale motor scores in the OFF state increased with age. The improvement in total dyskinesia scores occurred irrespective of age, but increased with duration of disease, duration of dyskinesias and baseline severity of dyskinesias. Five patients had transient neurological complications while facial paresis was permanent in one subject. Our results are similar to those obtained by others who used the time consuming microelectrode recording technique for localization. By simplifying the procedure in the way that we describe, the operation could become available to a greater number of patients.

Adult↗
PubMed1997

Lamotrigine trial in idiopathic parkinsonism: a double-blind, placebo-controlled, crossover study.

Increased glutamatergic transmission in the basal ganglia is implicated in the pathophysiology of idiopathic parkinsonism (IP). We investigated the effects of lamotrigine (LTG), a glutamate-release inhibitor, in the symptomatic treatment of IP in two double-blind, placebo-controlled studies. Single doses of L-dopa/carbidopa (equal to 50% of the usual morning dose) were administered together with either LTG (100, 200, or 400 mg) or two random placebo doses in 14 patients with IP. The patients were assessed using the Modified Columbia Rating Scale (MCRS) and the Purdue Pegboard Test (PPBT) at multiple intervals over 8 hours. There were no significant differences between the placebo doses and the three doses of LTG on the MCRS and PPBT scores. In a 3-month study, 12 patients took LTG titrated up to 400 mg or placebo with their antiparkinsonian medication for 3 months and were then crossed over. Nine of 12 patients did not complete the study because of dyskinesia (n = 2), hallucinations (n = 3), and deterioration of parkinsonian symptoms (n = 4) on LTG. There was no significant difference between placebo and LTG on the MCRS and PPBT in the three patients who completed the study. The results failed to demonstrate any symptomatically beneficial effects of LTG in IP.

Adult↗
PubMed1997

Fluorodopa and raclopride PET analysis of patients with Machado-Joseph disease.

We performed [18F]6-fluoro-L-dopa (6-FD) and [11C]raclopride (RAC) PET studies in six patients with Machado-Joseph disease (MJD) (age, 17 to 61 years; duration of illness, 3 to 10 years), normal controls (n = 10 in 6-FD-PET, n = 8 in RAC-PET), and patients with idiopathic parkinsonism (n = 15 in 6-FD-PET). The youngest patient with MJD had prominent dystonia and pyramidal features (type 1 MJD), whereas the remainder were prominently ataxic (types 2 and 3 MJD). Striatal RAC binding was normal in patients with MJD. Striatal 6-FD influx constants (Ki) were low in the range of idiopathic parkinsonism in two patients with MJD (youngest and oldest patients), whereas striatal Ki were normal in the remaining patients with MJD. The impairment of the nigrostriatal dopaminergic pathway did not correlate with the phenotype, CAG repeat length, disease duration, or age of onset of patients with MJD. Our results suggest that striatal D2 receptors are normal and the nigral damage is diverse in MJD.

Adolescent↗
PubMed1997

Reproducibility of retinal and optic nerve head blood flow measurements with scanning laser Doppler flowmetry.

PURPOSE: To evaluate the interobserver variability and the reproducibility of retinal and optic nerve head capillary blood flow measurements performed with a new noninvasive equipment, the scanning laser Doppler flowmeter (Heidelberg Engineering, Heidelberg, Germany). METHODS: Blood flow measurements were performed during three independent sessions in six patients with glaucoma and five normal subjects using the scanning laser Doppler flowmeter (SLDF), which allows the visualization of perfused capillaries and vessels of the retina and optic nerve head and enables the quantification of capillary blood volume, flow, and velocity in any selected area of the perfusion map. To evaluate the interobserver variability in selecting the areas in the perfusion map to be measured, three observers tried to locate the same areas in the perfusion map of images obtained during the first session. To evaluate the reproducibility of the measurements, the observers measured correspondent areas in the peripapillary retina and in the optic nerve head of images from the three sessions. Areas of different sizes (10 x 10 pixels and 4 x 4 pixels) were measured. RESULTS: The agreement between readings performed by the three observers was very good, with the reliability coefficient for the various parameters varying from 0.90 to 0.98. The reproducibility of retinal and lamina cribrosa measurements with the 10 x 10 pixel square target was good (reliability coefficient for the different parameters ranging from 0.70 to 0.85) and much better than the reproducibility of the 4 x 4 pixel target. The measurements performed in the neuroretinal rim area also had poor reproducibility. The measurements from the patients with glaucoma tended to be more reproducible than those from normal subjects. CONCLUSIONS: The SLDF allows reproducible blood perfusion measurements of retinal and lamina cribrosa areas when a target square of 10 x 10 pixels is used.

Adult↗
PubMed1996

Ovulatory premenopausal women lose cancellous spinal bone: a five year prospective study.

Healthy premenopausal women with regular cycles are believed to be increasing or maintaining bone density. However, few studies have prospectively documented spinal cancellous bone, the bone that changes rapidly in response to reproductive hormones, in this population. Furthermore, our previous one-year study documented that 24% of the one-year bone change by quantitative computed tomography (QCT) was related to subclinical ovulatory disturbances (short luteal phase and non-ovulation) in the presence of regular menstrual cycles. The purpose of this study was to document the cancellous bone change over five years in this initially ovulatory, premenopausal cohort of 66 healthy women. Thirty-seven women, who continued to be premenopausal and have regular cycles, completed this five-year study. Those enrolled differed only by being older and weighing less than those who could not be contacted (n = 19) or who declined to participate (n = 10). Documentation of current ovulatory characteristics was obtained for at least three cycles in 27 women. At the five-year assessment, the volunteers were 40.6 (range 26-47) years old, weighed 58.5 (41-77) kg, and were 160.9 (149-174) cm in height. All were premenopausal, healthy, nonsmokers with regular menstrual cycles (mean 27.7, range 24-33 days). Six women with intervening events (such as pregnancy or use of oral contraceptives) had interval (12 to 60 months) QCT changes similar to the remaining 31 (-7.98 vs. -4.92 mg/cm, p = 0.1, respectively). Mean five-year QCT was 143.0 +/- 20.2 mg/cm, whereas the initial mean value was 151.9 +/- 20.1 mg/cm. Significant QCT loss over five years (-8.9 +/- 6.2 mg/cm) (95% Cl -6.9 to -11.0) correlated with QCT change in the first year (r = 0.629, p < 0.001). First-year change was not related to the subsequent four-year interval change (r = -0.056, p = 0.74), however. Five-year QCT change was not related to age, weight, osteoporosis family history, estimated calcium intake, or exercise, but did correlate with year one luteal index (luteal/cycle length) (r = 0.339, p = 0.043). Significant cancellous spinal bone loss occurs in healthy, ovulatory premenopausal women, and is influenced by subclinical disturbances of ovulation.

Adult↗
PubMed1996

'Unqualified success' and 'unmitigated failure': number-needed-to-treat-related concepts for assessing treatment efficacy in the presence of treatment-induced adverse events.

BACKGROUND: Common indices for the quantal assessment of treatment efficacy are reviewed. The absolute risk reduction is a practical index for public health considerations. Its reciprocal has been termed the 'Number Needed to Treat' (NNT), representing the health effort that must on average be expended to accomplish one tangible treatment target. We extend the NNT to evaluate outcome combinations of treatment benefits versus treatment harms. METHODS: We describe the mathematical context of the NNT, and extend it to evaluate outcome combinations (treatment success/failure with/without treatment-induced adverse effects) in a treated population. These extensions are carried out assuming either independence or positive association between treatment benefit and treatment harm. A method is provided for calculating the standard errors of these extended NNT values. Applications to cost-effectiveness analysis are discussed. RESULTS: We calculate NNT in three recent therapeutic studies. The results of a trial of the prevention of strokes with warfarin in patients with non-valvular atrial fibrillation are analysed to evaluate treatment success (stroke prevention) against treatment-induced bleeds. An NNT-related cost-benefit analysis is also carried out. We also analyse the results of a study of two modalities of chemotherapeutic treatment in small-cell lung cancer, and of two modalities of surgical intervention in the treatment of cholelithiasis. CONCLUSIONS: The NNT are useful in direct evaluation of outcome-specific treatment benefits versus treatment-induced harms. They may also be used in cost-effectiveness analyses and are helpful in guiding public health programmes towards the identification of optimal treatment strategies.

Anticoagulants↗
PubMed1996

Arthritis and anti-inflammatory agents as possible protective factors for Alzheimer's disease: a review of 17 epidemiologic studies.

Alzheimer's disease (AD) lesions are characterized by the presence of numerous inflammatory proteins. This has led to the hypothesis that brain inflammation is a cause of neuronal injury in AD and that anti-inflammatory drugs may act as protective agents. Seventeen epidemiologic studies from nine different countries have now been published in which arthritis, a major indication for the use of anti-inflammatory drugs, or anti-inflammatory drugs themselves have been considered as risk factors for AD. Both factors appear to be associated with a reduced prevalence of AD. The small size of most studies has limited their individual statistical significance, but similarities in design have made it possible to evaluate combined results. We have used established methods of statistical meta-analysis to estimate the overall chance of individuals exposed to arthritis or anti-inflammatory drugs developing AD as compared with the general population. Seven case-control studies with arthritis as the risk factor yielded an overall odds ratio of 0.556 (p < 0.0001), while four case-control studies with steroids yielded odds ratios of 0.656 (p = 0.049) and three case-control studies with nonsteroidal anti-inflammatory drugs (NSAIDs) yielded an odds ratio of 0.496 (p = 0.0002). When NSAIDs and steroids were combined into a single category of anti-inflammatory drugs, the odds ratio was 0.556 (p < 0.0001). Population-based studies were less similar in design than case-control studies, complicating the process of applying statistical meta-analytical techniques. Nevertheless, population-based studies with rheumatoid arthritis and NSAID use as risk factors strongly supported the results of case-control studies. These data suggest anti-inflammatory drugs may have a protective effect against AD. Controlled clinical trials will be necessary to test this possibility.

Alzheimer Disease↗
PubMed1996

Presynaptic nigrostriatal function in genetically tested asymptomatic relatives from the pallido-ponto-nigral degeneration family.

Pallido-ponto-nigral degeneration (PPND) is a dominantly inherited disorder with parkinsonism. We performed PET with [18F]fluorodopa (FD) and, later, gene testing in 12 asymptomatic relatives at risk from a family with PPND and compared the striatal FD uptake constant (Ki) in them with 4 symptomatic individuals and 10 normal control subjects. Four relatives with positive linkage had a significantly reduced Ki from the normal control subjects but to a lesser degree than the symptomatic patients. The mean Ki in the relatives with negative linkage (n = 8) did not differ from normal control subjects. In conclusion, we identified reduced dopaminergic function in asymptomatic relatives with positive genetic linkage from the PPND family. Most of the reduction in this disorder occurs in the fifth decade, when the disease manifests clinically.

Adult↗
PubMed1996

Reproducibility and discriminating ability of fluorine-18-6-fluoro-L-Dopa PET in Parkinson's disease.

UNLABELLED: Fluorine-18-fluorodopa (F-Dopa) PET assesses the integrity of the nigrostriatal dopaminergic neurons in Parkinson's disease. It has been used in longitudinal studies to measure the progression of Parkinson's disease and the effects of medications and intracerebral transplants. The significance of changes in PET indices in such studies depends largely on the reproducibility of the F-Dopa PET measurements. METHODS: We performed repeated F-Dopa PET scans in 12 subjects with Parkinson's disease (between Hoehn and Yahr stages I and III) to measure scan-to-scan variations. Data were analyzed using five methods comprising two sets of regions of interest (ROIs) (total striatum and substriatal), the striatum-to-cortex ratio and two graphical methods (one using plasma radioactivity, the other using cortical radioactivity as the input function). We also studied the effectiveness of each method in discriminating between patients with Parkinson's disease and normal subjects using data obtained from a similar study in 10 normal subjects. RESULTS: We found reliability coefficients between 66% and 93%; the scan-to-scan intrasubject standard deviation ranged from 2% to 16% of the mean value depending on the method of analysis and the size of the ROIs. All methods discriminated significantly between patients with Parkinson's disease and normal subjects. The ability to discriminate, as reflected by the intergroup/intragroup ratio of variance, ranged from 2 to 18. CONCLUSION: These results permit selection of the best method of analysis for studies of nigrostriatal dopaminergic function.

Analysis of Variance↗
PubMed1995

Characterization of junctional rhythm after atrioventricular node ablation.

BACKGROUND: Catheter ablation of the atrioventricular (AV) node with radiofrequency current (RFC) is associated with the short-term onset of a junctional escape rhythm (JER) in nearly all patients. However, the origin of the JER and short-term thermal effects of RFC on this junctional pacemaker activity are ill defined. METHODS AND RESULTS: Short-term and noninvasive long-term follow-up studies were performed to examine the electrophysiological characteristics of the underlying JER in 45 patients who had undergone AV nodal ablation with RFC. Baseline characteristics and responses to overdrive ventricular pacing and intravenous atropine followed by an incremental isoproterenol infusion were determined. Short- and long-term responses were compared. HV intervals before and after ablation were 49 +/- 9 and 48 +/- 9 milliseconds, respectively (P = NS). Follow-up was 11 +/- 8.3 months. JER cycle length was 1526 +/- 298 milliseconds in the short-term setting and was present in 44 patients (98%) in the long-term setting, measuring 1426 +/- 223 milliseconds (P < .005). Junctional recovery times increased exponentially as overdrive pacing rates increased-there was no difference between short-term and long-term responses. Drug responses within each study were all significant when compared with baseline. However, there was no significant difference between short- and long-term responses, except at the highest dose of isoproterenol. Intravenous atropine (1 mg) caused an 8.6 +/- 9.3% decrease in JER cycle length in the short-term setting compared with a 7.6 +/- 7.3% decrease in the long-term setting. The decreases in JER cycle length with isoproterenol infusion (short-term versus long-term) were 10.1 +/- 9.6% versus 9.6 +/- 7.4% with 1 microgram/min, 15.8 +/- 11.7% versus 17.4 +/- 8.5% with 2 micrograms/min, 17.9 +/- 11.2% versus 21.4 +/- 9.1% with 3 micrograms/min (all P = NS), and 20.6 +/- 12.1% versus 24.8 +/- 9.1% with 4 micrograms/min (P < .01). CONCLUSIONS: Radiofrequency ablation of the AV node is associated with development of a JER that is stable in the long-term setting. The lack of change in HV interval after ablation locates the junctional pacemaker proximal to the central fibrous body. The pattern of drug responses suggests an origin within the proximal His bundle at its junction with the AV node rather than the AV node itself. The overall similarity between short- and long-term characteristics of junctional pacemaker activity mitigates against any reversible thermal effects of RFC on this pacemaker focus.

Aged↗