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Biomedical subjects

S Erdman

Publications and source records attributed to S Erdman.

At least 19 recordsLinked to original sources
PubMed1997

Single pass lead VDD pacing in children and adolescents.

Implantation of permanent pacemakers in children and adolescents is possible but usually is limited to single chamber generators. The natural growth of these patients may require physiological pacing, but until recently two leads were required for this type of pacing. The single pass lead VDD pacing mode makes possible physiological pacing by using only one lead, for both atrial sensing and ventricular sensing and pacing. The feasibility of VDD pacing using endocardial lead was evaluated in 16 children and adolescents with congenital or postsurgical atrioventricular block. Their mean age was 7.9 +/- 4.9 years (range 1-16 years) and the smallest patient's weight was 8.2 kg. In all the patients, a single pass pacing lead with atrial sensing rings and bipolar ventricular pacing and sensing capability was implanted through the left or right subclavian vein. The pacemaker generator was implanted in a rectopectoral position. The mean atrial electrogram during the implantation was 4.2 +/- 2.1 mV and 2.6 +/- 1.9 mV after a mean of 1 week. The ventricular pacing threshold was 0.5 +/- 0.2 V; the ventricular pacing impedance was 560 +/- 95 omega; and the ventricular electrogram amplitude was 9.9 +/- 2.1 mV. This is a first report to demonstrate the feasibility of atrial synchronous ventricular endocardial pacing using a single pass lead in a relatively large group of children and adolescents.

Adolescent↗
PubMed1996

Single lead VDD pacing: multicenter study.

Optimal treatment for patients with AV block and normal sinoatrial node (SA) function entails atrial sensing and ventricular pacing (VDD mode). Single-lead VDD pacing preserves AV synchrony, precludes the need to insert two leads, and makes the implanter's work simpler and quicker. Our objectives were to verify the performance of the Thera VDD pacing system (medtronic, Inc., Minneapolis, MN, USA), and evaluate the effectiveness of its atrial sensing and its ventricular sensing and pacing. In 165 patients, 150 adults (mean age 62 +/- 18 years) and 15 children (mean age 7 +/- 5 years) with 1 degree-3 degrees AV block and normal SA node function, a Thera VDD system (Models 8948 or 8968) was implanted. Intraoperative ventricular electrical measurements were not significantly different from those of VVI pacemakers. The mean amplitude of the atrial signal during implantation was 4.1 +/- 1.9 mV. Optimal atrial signals during implantation were usually obtained in the mid or lower part of the right atrium by using a special technique. Adequate atrial measurements remained stable throughout 24 months. There was no difference between serial measurements of atrial signal amplitudes at predischarge and during follow-up visits. Reposition of the lead was done in 2 patients (1.4%), and reprogramming to VVI in 7 patients: due to atrial fibrillation in 3 (1.8%) and due to atrial undersensing in 4 patients (2.4%). Thera VDD pacing is reliable and easy to manage with dependable atrial sensing and ventricular pacing. The survival rate of VDD pacing at 2 years was 96%.

Adolescent↗
PubMed1994

Plasticity in spinal opioid control of lower urinary tract function in paraplegic cats.

Spinal cord injury disrupts micturition reflexes, which produces morbidity. The contribution of endogenous opioid systems to urinary retention were assessed in chronic spinal cats by administering the opioid receptor antagonist, naloxone (5-500 micrograms kg-1, i.p.), to unanesthetized paraplegic cats while monitoring lower urinary tract function and observing hind limb reflexes. While naloxone had no overt effect in acute spinal cats, in chronic spinal cats naloxone induced the release of large volumes of urine and produced marked hind limb hyper-reflexia. Prominent tachyphylaxis and tolerance to the effects of naloxone were evident. Immunohistochemical studies indicated a marked increase in leucine enkephalin and dynorphin in sacral spinal neurons. Together, these data indicate hyperactivity of the endogenous spinal opioid system following recovery from spinal cord injury and, furthermore, suggest that the spinal neural circuitry may become 'dependent' upon elevated levels of endogenous opioid peptides.

Animals↗
PubMed1994

Cardiomyoplasty review: physiological principles and characteristics of electrically stimulated skeletal muscle. II. A therapeutic option.

Chronic heart failure continues unsolved as ever despite recent advances in cardiac surgery and pharmacological new armamentarium and remains a significant cause of death, regardless of etiology. Cardiomyoplasty (CMP), a new form of biomechanical ventricular support, has given new life to the field of mechanical circulatory support, providing a "bridge" to transplantation and serving as a possible alternative to surgical treatment. The geographic distribution of world experience in 401 patients shows that 80% were centralized in Europe (50%) and South America (30%). This review of the data analysis, documented improved changes in patients clinical status, further clarifies and appropriate patients population indications for DCMP as well as that more than 80% survival probability for NYHA class II & III and an early procedure related mortality of 8 to 10%.

Cardiomyopathy, Dilated↗
PubMed1994

Geometric reconstruction in left ventricular aneurysm. Surgical aspects and early results.

The early results of 79 patients who underwent left ventricular aneurysmectomy with geometric and circular reconstruction in a seven-year experience are analyzed. The most common indication for operation was congestive heart failure (78.4%), either isolated (25.3%) or with angina (53.1%). Sixty patients (76%) were in NYHA class III and 10 (12.6%) in NYHA class IV at the time of surgery. Fifty-eight (73.4%) underwent coronary artery by-pass graft surgery. Hospital mortality was 5.1%, in patients older than 60 (12%), in NYHA class IV (20%), with poor left ventricular function (EF < 0.30-20% and LVED > 25) (14%), and with extensive coronary artery disease (10%) were under increased risk. Low cardiac output and use of intra-aortic balloon pump were also associated risk factors. Other risk factors mentioned in the literature are discussed. There were no deaths from isolated left ventricular aneurysmectomy. The early results of this study and the early and late results of others using the same technique are better than the results obtained in previous studies of different types of correction, suggesting that this is the procedure of choice for treating left ventricular aneurysm.

Adult↗
PubMed1993

Localization of peripheral pulmonary nodules for thoracoscopic excision: value of CT-guided wire placement.

OBJECTIVE: One of the indications for the rapidly expanding use of thoracoscopic surgery as an alternative to thoracotomy is the excision of peripheral lung nodules. Nodules judged too small or too far from the pleural surface to be seen or palpated during thoracoscopy must be localized beforehand. The purpose of this study was to evaluate the feasibility and effectiveness of percutaneous placement of spring hookwires to localize such nodules before video-assisted thoracoscopy. SUBJECTS AND METHODS: Under CT guidance, 17 nodules in 14 patients were preoperatively localized with the Kopans breast lesion localization system. Three patients who had solitary nodules had thoracoscopic resections for diagnosis because a previous transthoracic needle or transbronchial biopsy had been unsuccessful. Four patients who had lesions less than 8 mm in diameter had thoracoscopic biopsies because transthoracic fine-needle aspiration biopsy was not likely to be diagnostic. Seven patients, who had a total of 10 nodules, had therapeutic wedge resections of either limited metastases or a second bronchogenic carcinoma. Mean nodule diameter was 10 mm (range, 3-20 mm). The mean distance from nodule to costal pleura was 9 mm (range, 0-25 mm). At the end of the procedure, wire placement was confirmed by CT scanning. After thoracoscopy, the surgeons were questioned about the stability and utility of each hookwire localization. RESULTS: In all 17 procedures, a hookwire was placed successfully. In one case, the wire dislodged before thoracoscopy (after a 6-hr preoperative delay and severe bending of the wire during induction of anesthesia). In 16 of the 17 resections, the surgeon thought that thoracoscopic identification of the lesion would not have been possible without hookwire localization. Only one localization, across a major fissure, required placement of a second wire to localize a nodule. Wire-related complications included two instances of serious pain, five cases of clinically insignificant pneumothorax, and one large pneumothorax requiring drainage before a second nodule in the same lung was localized. CT scanning showed presumed local pulmonary hemorrhage in six cases without hemoptysis or hemothorax. CONCLUSION: CT-guided hookwire localization is easily and safely performed and permits thoracoscopic resection of lung nodules, which might otherwise be impossible.

Adult↗
PubMed1992

Seven years of left ventricular pacing due to malposition of pacing electrode.

The case report is presented of a patient in whom an uncomplicated left ventricular transvenous pacing produced right bundle branch block (RBBB). A diagnostic echocardiography, confirmed by cine cardiovascular computed tomography, showed that there was no rupture of the right ventricle and diagnosed a left ventricular pacing, due to malposition of the pacing electrode. The patient was treated with aspirin and dipyridamole during the last 6 years of follow-up, without any complications, including 1 year of pacing, prior to admission.

Bundle-Branch Block↗
PubMed1991

Alterations in afferent pathways from the urinary bladder of the rat in response to partial urethral obstruction.

Afferent pathways from the urinary bladder were examined with axonal tracing techniques in normal female Wistar rats and in those with partial urethral ligation. Following injection of wheat germ agglutinin-horseradish peroxidase (HRP) into the bladder wall, HRP was detected in lumbosacral dorsal root ganglion cells and in afferent projections to the L6-S1 spinal cord at sites in laminae I, II, V-VII, and X known to receive visceral afferent input. Partial urethral ligation (6 weeks) produced a sixfold increase in bladder weight and altered the morphology of bladder afferent pathways. Changes included an increase in the average cross-sectional area of labelled neuronal profiles in L6 and S1 dorsal root ganglia in obstructed (766 +/- 378 microns 2, P less than 0.001) compared to control rats (528 +/- 189 mu 2). The cross-sectional area of the largest profiles also increased by approximately 40%. The mean number of labelled dorsal root ganglion cell profiles was similar in ligated (837 +/- 198) and control (883 +/- 352) groups. When compared to control animals the obstructed animals exhibited a 60% increase in the area of the labelled afferent terminal field in the intermediolateral region of the L6-S1 spinal cord. This increased labelling was even more remarkable given that the volume of tracer per bladder weight injected into the hypertrophied bladder was 87% less than controls. These results provide evidence that bladder afferents project to regions of the spinal cord known to regulate micturition and that these afferents can undergo morphological alterations and/or changes in axoplasmic transport in response to urethral ligation. Changes may occur in response to increased target organ mass, increased neural activity, or alterations in the levels or activity of neurotrophic factors.

Afferent Pathways↗
PubMed1991

Neonatal hepatitis and extrahepatic biliary atresia associated with cytomegalovirus infection in twins.

Prenatally acquired cytomegalovirus infection in twins was temporally associated with a discordant development of neonatal hepatitis and extrahepatic biliary atresia. This case presents evidence suggesting an association between perinatal cytomegalovirus infection and selected extrahepatic biliary atresia and neonatal hepatitis. Congenital cytomegalovirus infections and cytomegalovirus hepatitis are also discussed.

Biliary Atresia↗
PubMed1990

Postnatal development of opioid regulation of micturition in the kitten.

Endogenous opioids tonically regulate micturition in adult mammals. The present study sought to determine if opioids regulate micturition in neonatal kittens. Naloxone (up to 2 mg/kg given i.p. or i.v. to unanesthetized/ketamine-anesthetized or chloralose-anesthetized kittens, respectively), an opioid receptor antagonist, produced no effects in unanesthetized, ketamine-anesthetized, or chloralose-anesthetized kittens that had been prepared for bladder pressure recording, until 3 weeks of age. This indicates that endogenous opioids are not tonically regulating micturition in neonatal kittens. From 3 weeks up to at least 6 weeks of age, naloxone (100 micrograms/kg i.p. or i.v.) weakly facilitated bladder activity by transiently increasing the amplitude and/or duration of bladder contractions, but no effects on frequency of contractions was recorded. Morphine (up to 2 mg/kg given i.p. or i.v. to unanesthetized/ketamine-anesthetized or chloralose-anesthetized kittens, respectively), an opioid agonist, did not inhibit bladder contractions in unanesthetized or ketamine-anesthetized neonatal kittens, but it did inhibit (at a threshold dose of 100 micrograms/kg) and completely abolished (at a dose of 300 micrograms/kg) bladder activity in chloralose-anesthetized kittens in a dose-dependent, naloxone-reversible manner. Surprisingly, following morphine administration to unanesthetized or ketamine-anesthetized neonatal kittens, naloxone now produced an adult-like enhancement of bladder activity. These latter results indicate that opioid receptors, whose inhibitory effects are anesthetic-dependent, are present along the micturition reflex pathway in neonates. Immunohistochemical studies of the sacral spinal cord revealed that opioid peptides are distributed similarly in neonatal and adult cats.

Animals↗
PubMed1990

Morphological plasticity in efferent pathways to the urinary bladder of the rat following urethral obstruction.

Partial urethral ligation in female Wistar rats produces changes in the neural control of the lower urinary tract including bladder hyperactivity and facilitation of a spinal micturition reflex pathway. To gain insight into the mechanisms underlying these changes, axonal tracing studies were conducted to examine the postganglionic efferent limb of the micturition reflex pathway which originates in the major pelvic ganglion (MPG). Forty microliters of the tracer Fluoro-Gold (4%) were injected into the right side of the bladder in urethral-obstructed (n = 10) and control (n = 4) rats 6 weeks after urethral ligation or sham surgery. As a control Fast blue (40 microliters, 5%) was injected into the colon to label neurons in the MPG innervating the intestine. Obstructed rats exhibited a 6-fold increase (p less than 0.001) in bladder weight (0.848 gm) compared to controls (0.148 gm). A significant increase (p less than 0.001) in the size of labeled bladder postganglionic neurons in the MPG was noted in obstructed rats (576.4 microns 2, n = 4) as compared to controls (299.6 microns 2). However, labeled, colon postganglionic neurons in the MPG in obstructed (312.9 microns 2) rats were not enlarged compared to controls (359.4 microns 2). Neuronal hypertrophy was not associated with a change in the number of labeled MPG neurons in control and obstructed groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

Safety precautions in the management of patients with pacemakers when electrocautery operations are performed.

The hazards related to ten patients who underwent 11 urologic surgical procedures during a 36 month period were taken into consideration. Electrocautery was used in all instances and there were no complications. All of the pacemakers were preset for ventricular pacing and sensing inhibited or multiprogrammable and were reprogrammed during the operation to ventricular pacing fixed rate mode or magnet mode, with very satisfactory outcome. To avoid life-threatening situations arising from pacemaker inhibition or ventricular fibrillation during cautery for transuretheral resection, three basic factors were considered: 1, appropriate type of pacemaker; 2, the proper grounding of all medical electronic equipment used during the procedure, and 3, the directing of the complete flow of the electrocautery circuits substantially below the level of the pacemaker unit.

Accident Prevention↗
PubMed1986

Closed pericardial drainage for relief of pericardial tamponade.

The method of continuous catheter drainage for pericardial tamponade as used in 108 patients is described. The efficacy of this procedure in relieving tamponade resulting from a variety of diseases is demonstrated. Blood clot in the pericardium probably constitutes a contraindication to catheter drainage.

Cardiac Catheterization↗
PubMed1986

Polymorphous ventricular tachycardia and atrioventricular block.

Nine patients are presented who had polymorphous ventricular tachycardia (PMVT) occurring during atrioventricular (AV) block. There were five men and four women with a mean age of 80 +/- 9 years. Five patients had organic heart disease and the remaining four had primary conduction disease (bundle branch block). AV block was complete in four patients (2:1 in three, and paroxysmal in two). The mean ventricular cycle length (of the AV block rhythm) was 1567 +/- 203 ms. The mean QT interval was 0.64 +/- 0.09 s and the mean QTc was 0.51 +/- 0.06 s. When compared to a similar control group with AV block but without PMVT, the ventricular cycle length was similar but the QT and QTc were significantly longer. PMVT was usually of short duration (eight beats to 12 s) and in seven of these nine patients, frequent premature ventricular beats (PVBs) were recorded at various times from the occurrence of PMVT. This is in contrast to the control patients in whom PVBs were detected in one patient only. In conclusion, patients with AV block who develop PMVT usually have longer QT intervals and have detectable PVBs on routine ECGs, unlike similar patients with AV block but without PMVT. In a patient with AV block, a QT interval above 0.60 s and PVBs on the ECG seem to indicate an increased risk for the development of PMVT.

Aged↗
PubMed1985

Use of the Shaw Scalpel in pacemaker operations.

Pacemaker carriers are at risk when undergoing operations involving the use of diathermy. The Shaw Scalpel utilizes a method by which the cutting edge of the blade is heated to a selected temperature that seals blood vessels as they are cut. No electrical currents are passed to or through the patient and there is no sparking or electrical arcing to the tissue. This apparatus was used as the sole method of thermal coagulation in 20 patients undergoing replacement of pacemaker batteries.

Diathermy↗