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P A Levine

Publications and source records attributed to P A Levine.

At least 19 recordsLinked to original sources
PubMed2001

Pacemaker repetitive nonreentrant ventriculoatrial synchronous rhythm. A review.

Ventriculoatrial (VA) synchrony during dual chamber pacing can occur in any patient who has the ability to sustain repeated retrograde conduction. If the retrograde P wave is sensed, the result will be an endless loop tachycardia or repetitive reentrant VA synchrony. VA synchrony can also occur when a dual chamber pacemaker does not sense a retrograde P wave within the postventricular atrial refractory period. In this situation if the normally suprathreshold atrial stimulus at the end of the atrial escape interval is continually delivered when the atrial myocardium is physiologically refractory, the result will be a repetitive nonreentrant VA synchronous rhythm. Repetitive nonreentrant VA synchrony may produce unfavorable hemodynamic consequences and the pacemaker syndrome. It represents an example of functional atrial undersensing combined with functional loss of atrial capture. Management requires modification of the programmed settings of the pacemaker and utilization of certain algorithms designed for other functions but nevertheless effective in this situation.

Cardiac Pacing, Artificial↗
PubMed2001

Evaluation of omeprazole in the treatment of reflux laryngitis: a prospective, placebo-controlled, randomized, double-blind study.

OBJECTIVES: Proton-pump inhibitors are often recommended in the treatment of laryngitis secondary to gastric reflux. Despite prospective treatment studies reporting high efficacy, only one previous report has been placebo-controlled and blinded. The objective of this study was to determine the efficacy of omeprazole in treating proven reflux laryngitis. STUDY DESIGN: Prospective, placebo-controlled, randomized, double-blind clinical trial. METHODS: Fifty-three patients with one or more reflux laryngitis symptoms were recruited to undergo 24-hour dual-channel pH probe testing. Thirty patients with more than four episodes of laryngopharyngeal reflux were enrolled. By random assignment, 15 patients received 40 mg omeprazole twice a day and the other 15 received placebo for a period of 2 months. Symptoms (hoarseness, throat pain, lump in throat sensation, throat clearing, cough, excessive phlegm, dysphagia, odynophagia, and heartburn) and endoscopic laryngeal signs (erythema, edema, and mucus accumulation) were recorded initially, at 1 month, and 2 months. RESULTS: In general, most symptom scores improved over time for both the omeprazole and placebo groups. Hoarseness, when patients begin with low hoarseness symptom scores, and throat clearing improved significantly more in patients on omeprazole than in those on placebo during the 2-month study. Throat pain, lump in throat sensation, excessive phlegm, difficulty swallowing, pain with swallowing, and heartburn showed improvement in both treatment arms, signifying the possibility of a placebo effect. Endoscopic laryngeal signs did not change significantly over the course of the study for either treatment group. CONCLUSIONS: A placebo effect appears to exist in the treatment of reflux laryngitis. However, hoarseness, when initially scored low, and throat clearing resulting from reflux laryngitis are effectively treated by omeprazole.

Adult↗
PubMed2001

Case report: complex arrhythmia induced by noncompetitive atrial pacing algorithm of DDDR pacemaker.

This report describes the occurrence of a repetitive nonreentrant ventriculoatrial (VA) synchronous rhythm precipitated by the noncompetitive atrial pacing algorithm of a Medtronic DDDR pacemaker. This algorithm delivers an atrial stimulus 300 ms after the detection of an atrial signal in the postventricular atrial refractory period of the pacemaker. In our patient, the atrial stimulus released by the algorithm was ineffectual because it encountered prolonged refractoriness of the atrial myocardium. This situation produced a repetitive nonreentrant VAl synchronous rhythm in the setting of retrograde VA conduction.

Algorithms↗
PubMed2000

The effect of mechanoreceptor stimulation of the laryngopharynx on the oesophago-gastric junction.

Stimulation of the pharynx by injection of minute amounts of water induces prolonged period of lower oesophageal sphincter (LOS) relaxation and augmentation of the crural diaphragm (CD) contraction. The purpose of this study was to determine the effects of stimulating mechano-receptors at the laryngopharynx on the LOS and CD by using an air pulse stimulation device. Air pulses were delivered via the internal channel of a flexible endoscope. Oesophageal, LOS, and CD pressures; CD electromyogram; and oesophageal pH 5 cm above the LOS were recorded in nine healthy subjects. Stimulation of the laryngopharynx induced LOS relaxation in the absence of swallow and oesophageal peristalsis. The stimulation of epiglottis and arytenoid produced higher incidence of LOS relaxation compared to the base of tongue. The magnitude of LOS relaxation differed significantly between the three anatomical sites, with greater relaxation occurring at the epiglottis and arytenoid compared with the base of the tongue. None of the LOS relaxations induced by laryngeal stimulation resulted in inhibition of the CD or gastroesophageal reflux. We conclude that stimulation of the laryngopharyngeal mechanoreceptors induces LOS but not CD relaxation. The LOS relaxation induced by laryngopharyngeal stimulation is not accompanied by acid reflux in fasting state.

Adult↗
PubMed2000

Device eccentricity: postmagnet behavior of DDDR pacemakers with automatic threshold tracking.

The normal pacing system function associated with the AutoCapture Pacing System algorithm triggered concern on the part of the clinical staff caring for the patient when the initiation of a threshold search sequence was detected during a transtelephonic follow-up evaluation. The analysis of the rhythm demonstrates that the behavior of the system is normal and consistent with the design of the AutoCapture algorithm. As a variety of new algorithms are introduced, similar unexpected but normal behaviors can be anticipated.

Algorithms↗
PubMed2000

Enhanced rate response algorithm for orthostatic compensation pacing.

Upon orthostatic stress after a period of rest, the heart rate increases rapidly to maintain cardiac output and minimize the fall in arterial pressure. Pacemaker patients are often prone to a deficient response to orthostatic stress. This may cause lightheadedness and, in rare patients with autonomic dysfunction, syncope. To alleviate these undesirable consequences, an enhanced rate response algorithm was developed using an accelerometer. The pacemaker generates two signals from its accelerometer: instantaneous activity level (Act) and long-term change in activity level (ActVar). Low values of both Act and ActVar indicate a resting state. An increase in Act while ActVar remains low indicates the onset of motion after prolonged rest. Upon detecting this transition, the algorithm increases the pacing rate to a programmable orthostatic compensation rate for a programmable duration. A taped-on pacemaker with this algorithm was evaluated in three healthy women and two healthy men, 36 +/- 8 years of age. Electrocardiogram and ventricular pacing pulses were recorded by a 24-hour ambulatory system. Each trigger of the orthostatic compensation rate was verified against a > 10 beats/min increase in heart rate, a response classified as appropriate. The overall specificity of the algorithm among the five subjects was 78%. The nocturnal specificity (10 PM to 7 AM) was 98%, considerably higher than during daytime (72%). In conclusion, a pacing algorithm to alleviate orthostatic stress was developed, which was highly specific during the night hours.

Acceleration↗
PubMed2000

Schwannoma of the cervical sympathetic chain. The Virginia experience.

We present 4 cases of schwannomas arising from the cervical sympathetic chain. These lesions are uncommon and most often present as an asymptomatic solitary neck mass. Preoperative diagnosis can be difficult, even with the aid of computed tomography, magnetic resonance imaging, ultrasound, and angiography. While a paraganglioma can often be ruled out, exact determination of the nerve of origin is frequently elusive until the time of surgery. Operative excision remains the treatment of choice, often requiring sacrifice of a portion of the sympathetic chain. Postoperative Horner's syndrome is common, but does not appear to have an adverse effect on the patient.

Autonomic Nervous System Diseases↗
PubMed1999

Esthesioneuroblastoma: reflections of a 21-year experience.

OBJECTIVES: To evaluate the results of standardized treatment of esthesioneuroblastoma at a single institution during a 21-year period and calculate pertinent parameters, i.e., metastatic disease (local, regional, distant), disease-free survival, and complications of treatment. STUDY DESIGN: A retrospective review was conducted of all patients treated at a single institution from September 1976 through May 1998. METHODS: Only those patients who received their complete evaluation and treatment at our institution were included in this analysis. Thirty-five patients met this criterion. In addition, results of epidemiological, pathological, and molecular analyses were evaluated to seek accurate indicators for clinical outcomes. RESULTS: Six percent of patients presented with cervical metastatic disease, but ultimately 25.7% developed at least one episode of cervical metastases; 14.3% of patients developed a local recurrence an average of 6 years after diagnosis; and 37% of the patients ultimately developed at least one episode of metastatic disease. The disease-free survival for this cohort of 35 patients was 80.4% at 8 years. CNS complications occurred in 25.7% of the patients, 22.9% had orbital complications, 20% had systemic posttreatment problems, 18.2% had chemotoxic sequelae, 8.6% had infectious complications, and 14.3% had cosmetic sequelae. No epidemiological, pathological, or molecular factors appeared to be more accurate clinical indicators than the Kadish staging system. CONCLUSIONS: This series of esthesioneuroblastoma patients (N=35) reflects an 8-year disease-free survival of 80.4%, representing a significant number of patients treated and followed at one institution for an extended period of time. No valuable pathological or molecular indicators to predict aggressive clinical behavior were found. The average time interval before recurrent disease developed was more than 6 years, far greater than that expected for other sinonasal malignancies. Therefore, extended follow-up is necessary for this patient group.

Adolescent↗
PubMed1998

Sebaceous carcinoma. Tumor progression through mutational inactivation of p53.

BACKGROUND: Sebaceous carcinoma may masquerade for years as an inflammatory condition. In many cases, this may be because of the presence of longstanding intraepithelial disease (e.g., dysplasia or carcinoma in situ), which eventually progresses to invasive carcinoma recognized through tumefaction and a worsening clinical presentation. The mechanism for this tumor progression is unknown. In the Far East, human papilloma virus (HPV) has been suggested to play a role in the development of sebaceous carcinoma by inactivating tumor suppressor gene p53. Here, the authors explore the molecular basis of the progression of ocular sebaceous carcinoma. METHODS: Cases of sebaceous carcinoma seen at the University of Virginia, Department of Ophthalmology, during the period from 1989 to 1996 were analyzed for HPV infection by in situ hybridization and polymerase chain reaction. The expression of p53, p21WAF-1, Bcl-2, and epithelial membrane antigen was examined by immunohistochemistry. In one of the cases, frozen tumor was available, allowing exons 5 through 9 of the p53 gene to be sequenced. RESULTS: Seven cases were identified, all of which were from women. All were negative for HPV. In cases in which disease was restricted to dysplasia (carcinoma in situ), p53 but not p21WAF-1 was negative. In contrast, cases that contained a component of invasive or metastatic carcinoma showed striking hyperexpression of nuclear p53 in all of the malignant cells. In one of these cases, a G:C-->T:A transversion was found in the p53 gene. This mutation, characteristic of bulky carcinogens, substituted phenylalanine for cysteine 277, a residue that participates in hydrogen bonding to the p53 DNA binding consensus sequence. CONCLUSIONS: Mutational inactivation of p53 may be involved in the progression of sebaceous carcinoma.

Adult↗
PubMed1998

Otolaryngology.

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Animals↗
PubMed1998

The role of preoperative adjuvant treatment in the management of esthesioneuroblastoma: the University of Virginia experience.

OBJECTIVE: Multidisciplinary management of esthesioneuroblastoma has effected markedly increased survival during the past 20 years. The potential for radical craniofacial surgery for complete en bloc resection, the availability of advanced neuroimaging modalities, and the incorporation of neoadjuvant therapy into treatment strategies for tumor remission have all contributed to this accomplishment. However, a standard protocol for the management of these lesions has not been accepted; preoperative radiation and chemotherapy have been advocated, but neither radiographic nor clinical response has been quantified. METHODS: Thirty-four consecutive patients with biopsy-proven esthesioneuroblastoma treated at one institution from 1976 to 1994 were reviewed to determine the effects of preoperative radiation therapy, with or without chemotherapy, on tumor size and long-term survival. RESULTS: In a multivariate regression analysis, advanced age was predictive of decreased disease-free survival (P=0.008), whereas advanced Kadish stage was associated with a borderline higher rate of disease-related mortality (P=0.056). Two-thirds of the patients showed a significant reduction in tumor burden with adjuvant therapy. Patients with response to neoadjuvant therapy demonstrated a significantly lower rate of disease-related mortality (P=0.050). In this series, the overall 5- and 10-year survival rates were 81.0 and 54.5%, respectively. CONCLUSION: Preoperative neoadjuvant therapy provides a valuable complement to radical craniofacial resection, leading to reduction in tumor burden. Patients experiencing reduction in tumor volume by neoadjuvant therapy demonstrate an improved prognosis.

Adolescent↗
PubMed1998

Pacemaker-mediated polymorphic ventricular tachycardia.

A patient with refractory bradycardia dependent polymorphic ventricular tachycardia (PMVT) underwent permanent pacemaker placement for suppression of her arrhythmia. Following implant, the patient had recurrent PMVT. Interrogation of the device revealed a factory programmed feature (+ PVARP on PVC) designed to prevent pacemaker-mediated tachycardia that led to cycle length variability and subsequent arrhythmia recurrence. This feature was deactivated and the patients' arrhythmia did not recur.

Aged↗
PubMed1998

Activity-controlled circadian base rate.

The current pacing rates are clustered around a fixed base rate since pacemaker patients are usually sedentary, resting, or sleeping most of the time. This fixed base rate is either too low for daytime hemodynamic support or too high for nighttime rest and recovery. Multiple Holter studies involving normal individuals have suggested that the resting base rate fluctuates during the course of the day. The circadian base rate (CBR) algorithm was designed to provide patients with a circadian change in paced resting rate and a normal rate distribution. The CBR algorithm, using a sophisticated accelerometer sensor, was developed and tested using the downloaded activity data from patients implanted with Trilogy DR+ pacemakers. Twenty-five patients (19 men, 6 women, age 72 +/- 9 years) were studied. Trilogy DR+ is able to record the detailed sensor and system behavior data for a week. During outpatient visits, the pacemaker was interrogated and the data accumulated in the pacemaker memory were downloaded. The CBR algorithm was applied to the activity variance histogram to calculate the base rate and to construct its histogram. The base rates in the CBR histogram are generally below 100 ppm with a distribution that mimics the natural sinus rate distribution of normal subjects. The CBR algorithm provides the highest daytime rates for hemodynamic support and the lowest nighttime rates for cardiac recovery, with a smoothly changing base rate modeling the normal circadian variation in heart rate.

Aged↗