PubMed Health⌕ Search

Biomedical subjects

D Newman

Publications and source records attributed to D Newman.

At least 19 recordsLinked to original sources
PubMed1992

An anatomically guided approach to atrioventricular node slow pathway ablation.

Radiofrequency ablation of the "slow" pathway of the atrioventricular (AV) node reentrant circuit may be guided by electrophysiologic ("slow pathway potential") or anatomic landmarks. Experience with a systematic, anatomically guided approach in 25 patients (20 women and 5 men, aged 38 +/- 15 years) with typical AV node reentry is described. The slow pathway is assumed to be the posterior input to the AV node, approaching the nodal region in the corridor between the tricuspid annulus and the orifice of the coronary sinus. A series of radiofrequency lesions are given to interrupt this corridor at its entrance to Koch's triangle. If this is unsuccessful, the series of lesions are repeated progressively at higher levels approaching the AV node. The major end point for success is elimination of the slow pathway as determined by extrastimulus testing. A mean of 1.2 +/- 0.2 ablative sessions (20 +/- 12 applications of energy) achieved clinical success in 24 of 25 patients (96%) at a follow-up of 8.6 +/- 2.2 months. Anterograde Wenckebach cycle length increased from 361 +/- 67 ms to 398 +/- 70 ms (p = 0.01), yet the atrio-Hisian interval in sinus rhythm did not change (69 +/- 17 ms before vs 65 +/- 15 ms after ablation), p = 0.22. Retrograde Wenckebach cycle length was not affected (348 +/- 78 ms before vs 366 +/- 82 ms after ablation). During ablation, transient third-degree AV block occurred in 6 patients with no permanent sequelae. This approach provides a systematic, expedient technique to eliminate slow pathway conduction based on anatomic landmarks.

Adult↗
PubMed1992

Use of telemetry functions in the assessment of implanted antitachycardia device efficacy.

Twenty patients (aged 50 +/- 21 years and mean left ventricular ejection fraction 37 +/- 17%) with recurrent ventricular arrhythmias were treated with an investigational, implantable combined antitachycardia-pacing cardioverter defibrillator. The device's telemetry capabilities include both stored (1-second snapshots) and real-time display of endocardial and device-circuit signals. The device can store these before, during and after up to 50 tachycardia and antitachycardia pacing episodes. All stored events are indexed to a 24-hour internal clock. During 10.1 +/- 5.1 months of follow-up, the device was used in 11 of 20 patients. In the entire group, antitachycardia pacing was activated on 44 +/- 14 occasions per patient (total 874) and shock delivery occurred on 8 +/- 14 occasions per patient (total 156). Reconstruction by stored telemetry of all device-therapy episodes was possible. Twenty-six percent of all shocks delivered were not appropriate and were due to atrial arrhythmias in 2 patients and dysfunction of the sensing lead in 3. The absence of a relation between symptoms and appropriate shock delivery was documented in 1 patient. Antitachycardia pace acceleration occurred in 5.3% of cases; 7% of attempts at pacing were unsuccessful and needed shock therapy. It is concluded that the enhanced telemetry available in newer antitachycardia devices enables more accurate assessment of device use and enhances diagnosis of inappropriate therapy delivery.

Electric Countershock↗
PubMed1992

Survival after implantation of the cardioverter defibrillator.

The actuarial survival of 60 consecutive recipients of the implanted cardioverter defibrillator (ICD) were compared with 120 matched concurrent medically treated patients using a case-control design. All ICD patients and controls presented with either sustained ventricular tachycardia or ventricular fibrillation. Controls were matched to ICD recipients according to 5 variables: age, left ventricular ejection fraction, arrhythmia at presentation, underlying heart disease and drug therapy status. Mean ages were 58 and 59 years in ICD patients and controls, and the average ejection fractions were 36 and 35%. Coronary artery disease was present in 75 and 79% of ICD patients and controls, respectively. During follow-up, sudden deaths were fewer in ICD recipients than in controls (5 vs 10%, p less than 0.01). At 1 and 3 years, actuarial survival was 0.89 vs 0.72 and 0.65 vs 0.49 for ICD recipients and controls. The 5-year actuarial survival curves were significantly different by the Cox proportional hazards model (p less than 0.05). It is concluded that in this retrospective case-control study, the use of the ICD in the management of patients at risk for sudden death results in improved probability of survival.

Actuarial Analysis↗
PubMed1992

Speech naturalness and prolonged-speech treatments for stuttering: further variables and data.

It is well known that unusual speech quality may result from stuttering treatments that are based on prolonged speech. However, empirical information concerning the speech quality associated with those treatments is lacking. The present study was designed to contribute such empirical information. Results indicated that speech quality assessments of posttreatment clients, using Martin, Haroldson, and Triden's (1984) speech naturalness scale, gave similar results regardless of whether they were based on monologues or conversations. The speech quality of those clients remained stable at the conclusion of their treatment program. Further, there was a significant, positive correlation between pretreatment speech measures and measures of speech naturalness made after the establishment of stutter-free speech. The subjects whose pretreatment stuttering was the most severe had posttreatment speech naturalness scores that were more than two scale values worse than the subjects whose pretreatment stuttering was the least severe. Speech naturalness scale scores are presented for nonstutterers and posttreatment stutterers and these data are compared with existing findings.

Adolescent↗
PubMed1992

Variability of acoustic segment durations after prolonged-speech treatment for stuttering.

Existing literature suggests that one of the effects of treatment based on prolonged speech is increased durations of acoustic segments. However, the external validity of the data concerned may be questioned because the data were not based on spontaneous speech samples and were gathered from subjects with unknown treatment histories. With this in mind, the present investigation used young clients with no history of treatment based on prolonged speech and obtained pretreatment and posttreatment acoustic measures from spontaneous speech samples. Acoustic measures showed no significant posttreatment increases in durations of acoustic segments. However, for the acoustic measure of vowel duration and a measure of articulation rate, posttreatment speech samples showed significantly reduced variability. The potential theoretical and practical relevance of these findings is discussed.

Adolescent↗
PubMed1992

Effects of sympathetic stimulation on use dependence of lidocaine, mexiletine, and quinidine in an intact canine model.

The use- or rate-dependent effects of a continuous infusion of lidocaine (n = 6, serum level 3.1 +/- 0.34 micrograms/mL), mexiletine (n = 8, serum level 7.08 +/- 0.90 micrograms/mL), and quinidine (n = 6, serum level 6.8 +/- 1.22 micrograms/mL) were studied in an open chest canine preparation. A use-dependent effect on conduction was assessed by measuring the change in the His to surface ventricular activation (HV) time at differing atrial paced rates during drug infusion. Global sympathetic activation was achieved by nondecentralized left stellate ganglion stimulation (4-10 Hz, 6-12 V, 2 ms) and use dependence at the same cycle lengths was compared. Repolarization times were measured from epicardial monophasic action potentials recorded from the anterior left ventricle throughout the study. There was no significant change in the HV time during control studies with or without left stellate stimulation. Use-dependent slowing of conduction was seen in all studies during drug infusion. This was evident at cycle lengths of 300-190 ms for quinidine and at cycle lengths less than 250 ms for lidocaine and mexiletine. Stellate stimulation attenuated use dependence in all studies. This effect was significant from cycle lengths of 300-190 ms for lidocaine and quinidine and at cycle lengths shorter than 230 ms for mexiletine (p less than 0.05). Stellate stimulation significantly reduced use-dependent prolongation of the HV interval by an average of 60%. During stellate stimulation there was a nonsignificant trend towards cycle length independent shortening of action potential duration both at baseline and in the presence of drugs.(ABSTRACT TRUNCATED AT 250 WORDS)

Action Potentials↗
PubMed1992

Urinary albumin and low molecular weight protein excretion in the nephrotic syndrome--sequential studies during corticosteroid treatment.

In a preliminary investigation into the behaviour of low molecular weight proteins in the nephrotic syndrome, we have measured urinary concentrations of albumin, alpha-1-microglobulin (alpha 1-m) and retinol-binding protein (RBP) in six children for up to 11 days during the course of steroid therapy for nephrotic syndrome. The results in part support the concept of independent proximal tubular absorption of albumin and low molecular weight proteins, and indicate that in the nephrotic syndrome the excretion of RBP and alpha 1-m, two generally accepted markers of tubular proteinuria, is anomalous.

Adrenal Cortex Hormones↗
PubMed1991

Scintigraphic assessment of sympathetic innervation after transmural versus nontransmural myocardial infarction.

To evaluate the feasibility of detecting denervated myocardium in the infarcted canine heart, the distribution of sympathetic nerve endings using I-123 metaiodobenzylguanidine (MIBG) was compared with the distribution of perfusion using thallium-201, with the aid of color-coded computer functional map in 16 dogs. Twelve dogs underwent myocardial infarction by injection of vinyl latex into the left anterior descending coronary artery (transmural myocardial infarction, n = 6), or ligation of the left anterior descending coronary artery (nontransmural myocardial infarction, n = 6). Four dogs served as sham-operated controls. Image patterns were compared with tissue norepinephrine content and with histofluorescence microscopic findings in biopsy specimens. Hearts with transmural infarction showed zones of absent MIBG and thallium, indicating scar. Adjacent and distal regions showed reduced MIBG but normal thallium uptake, indicating viable but denervated myocardium. Denervation distal to infarction was confirmed by reduced norepinephrine content and absence of nerve fluorescence. Nontransmural myocardial infarction showed zones of wall thinning with decreased thallium uptake and a greater reduction or absence of MIBG localized to the region of the infarct, with minimal extension of denervation beyond the infarct. Norepinephrine content was significantly reduced in the infarct zone, and nerve fluorescence was absent. These findings suggest that 1) MIBG imaging can detect viable and perfused but denervated myocardium after infarction; and 2) as opposed to the distal denervation produced by transmural infarction, nontransmural infarction may lead to regional ischemic damage of sympathetic nerves, but may spare subepicardial nerve trunks that course through the region of infarction to provide a source of innervation to distal areas of myocardium.

3-Iodobenzylguanidine↗
PubMed1991

Lack of bone accretion and amenorrhea: evidence for a relative osteopenia in weight-bearing bones.

Bone mineral density (BMD) was studied in young exercising amenorrheic girls to determine if density was compromised and the change related to injury. Ninety-eight volunteers (professional ballet dancers and controls) were studied in a cross-sectional study. Dancers and controls were further subdivided into normally cycling and amenorrheic subjects. Amenorrhea significantly lowered bone density of the spine (P less than 0.0001), wrist (P less than 0.03), and metatarsal (P less than 0.01); effects on the wrist were eliminated by controlling for age while controlling for weight eliminated all effects of amenorrhea at three sites. BMD of the metatarsal, a weight-bearing bone, showed an interaction between amenorrhea and dancing (exercising) P less than 0.035); surprisingly, dancing was associated with a further lowering of bone density. This interaction was eliminated when controlling for age, but not when controlling for weight. With multiple comparisons of the groups, spine, wrist, and metatarsal bone density was significantly lower in amenorrheic dancers when compared to normal dancers (P less than 0.05), even when controlling for age and weight in the metatarsal (P less than 0.05), and age in the spine (P less than 0.05). Estradiol levels correlated with bone density of both the wrist and the spine (r = 0.25, r = 0.23, P less than 0.02). Metatarsal density correlated with estradiol levels only in the dancers (r = 0.34, P less than 0.02). The only variable found to correlate with the occurrence of stress fractures was age of menarche. This was also the only variable of 9 (BMD of the wrist, spine or foot, calories ingested and expended, amount of calcium ingested, involvement in high energy activity, age of menarche or presence of amenorrhea) to predict stress fractures. Thus, BMD is significantly affected by the presence of amenorrhea but the effects are generally weight dependent. The compensatory increase in bone density generally seen in stressed bones, such as the metatarsal in ballet dancers, is deficient in amenorrheic premenopausal women even when controlling for weight but this effect may be age and estrogen dependent. Bone mass may not accumulate in the same manner in adolescents as in the mature women, thus putting them at risk for injury.

Adolescent↗
PubMed1991

The painful shoulder: Part I. Extrinsic disorders.

Shoulder disorders are most commonly manifested by pain and limited function. Careful history and examination help the physician localize the problem to the shoulder joint, the surrounding tissues or adjacent sites that can cause referred pain to the shoulder. Common extrinsic causes of shoulder pain include postural problems and cervical spine disorders.

Diagnosis, Differential↗
PubMed1991

The painful shoulder: Part II. Intrinsic disorders and impingement syndrome.

Intrinsic disorders that can cause shoulder pain include arthritis, gout, pseudogout and osteonecrosis. In its mildest form, impingement syndrome may cause only minimal discomfort. At its worst, impingement syndrome may lead to rotator cuff tear. Bicipital tendinitis and rupture of the biceps tendon may also be associated with impingement. Early rehabilitative intervention is important. Physical therapy is directed toward restoring range of motion and muscle strength.

Adult↗
PubMed1990

Effect of platelet release products on cytosolic calcium in cardiac myocytes.

The effect of platelet release products on cytosolic calcium [( Ca++]i) was examined by monitoring the fluorescence of chick embryonic heart cells loaded with the fluorescent calcium indicator indo-1 AM. Cell free filtrate of platelet release products was obtained from rabbit platelets activated with thrombin or collagen. This filtrate caused a rapid increase in both systolic and diastolic [Ca++]i in a dose-dependent manner. The effect was not blocked by pretreating the platelets with aspirin or a thromboxane synthetase inhibitor. It was not mimicked by a thromboxane analog, or by several substances known to be released from platelets including ADP, serotonin, or platelet activating factor. Apyrase or ATP-gamma S had no effect on the activity. The responsible product was heat-sensitive, trypsin-sensitive, and partitioned into the aqueous phase of a chloroform suspension. It has a low molecular weight (less than 3kD) and is sensitive to 2-mercaptoethanol. Protease inhibitor appears to prolong the activity. These results suggest that trypsin-sensitive peptide(s) released from activated platelets can increase [Ca++]i in cardiac cells.

Animals↗
PubMed1990

Assessment of hearing loss in elderly people: the feasibility of a nurse administered screening test.

This paper examines the findings and implications of an exploratory study which was designed to determine the feasibility of a nurse administered hearing screen test for elderly patients. Theoretical and practical considerations which influenced the design of the hearing assessment test (HAT) and the method of the study are discussed. A sample of 27 elderly hospital inpatients, with a mean age of 81 years, participated in the study. The results of the new HAT were validated by comparison with audiometric assessment results. Analysis using the Generalized Linear Model showed a significant (P less than or equal to 0.01) relationship between the total HAT score and the audiometric measures, with the exception of the audiometric classification of hearing loss which was significant at P less than or equal to 0.05. The results demonstrate that the HAT is a potentially useful tool for nurses to use, but that refinement of the scale and further validity and reliability testing is required before it can be adopted as part of the nursing assessment of elderly people.

Aged↗