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Biomedical subjects

L Bray

Publications and source records attributed to L Bray.

11 recordsLinked to original sources
PubMed1995

Tissue pH as an indicator of mRNA preservation in human post-mortem brain.

The relationship between pH and mRNA preservation in post-mortem human brain was examined using in situ hybridization histochemistry and Northern hybridization with oligonucleotide probes in a large group of human subjects, including control and neuropathological cases. Tissue pH was found to correlate strongly with preservation of four mRNA species in three brain areas. Tissue with low pH, assumed to result from prolonged terminal hypoxia, contained reduced or absent mRNA, while tissue with higher pH was found to contain quantifiable amounts, the values for pathological brain samples being comparable to those for control material of similar pH. Measurement of tissue pH provides a simple means to screen post-mortem brain for mRNA preservation and is suggested as a means to match material in case-control studies of human neurodegenerative disease.

Adult↗
PubMed1993

Experience with three different third-generation cardioverter-defibrillators in patients with coronary artery disease or cardiomyopathy.

Clinical investigations are being performed in multiprogrammable devices whose therapeutic options include antitachycardia pacing, cardioversion, defibrillation and bradycardia pacing. Three different third-generation devices were implanted in 46 research patients at 1 clinical center to document their safety and efficacy for the treatment of malignant ventricular arrhythmias. Additionally, the purpose of the study was to determine if antitachycardia pacing is a desirable and frequently used feature of tiered devices. The Medtronic PCD was implanted in 15 patients (12 men, mean age 60 +/- 13 years, mean ejection fraction 40 +/- 15%), the Ventritex Cadence in 21 patients (17 men, mean age 65 +/- 10 years, mean ejection fraction 38 +/- 12%), and the CPI VENTAK PRx in 10 patients (8 men, mean age 63 +/- 14 years, mean ejection fraction 31 +/- 8%). All patients presented with cardiac arrest or ventricular tachycardia. During follow-up of 10 +/- 6 months (range 1 to 19), 70% of the 20 patients with antitachycardia pacing activated used the feature for spontaneous ventricular tachycardia. The antitachycardia pacing parameters were reprogrammed 20 times in 15 patients. Two thousand six hundred thirty-eight of 2,675 (98%) antitachycardia pacing attempts successfully terminated spontaneous tachyarrhythmias. Low-energy cardioversion or defibrillation terminated tachyarrhythmias in patients where pacing was unsuccessful. One hundred forty-eight episodes of tachycardia were successfully treated directly by shocks in 16 of 46 patients (35%). There were no deaths due to device failure. This initial single-center clinical experience suggests that the PCD, Cadence and VENTAK PRx are all safe and effective tiered therapy devices for the treatment of malignant ventricular arrhythmias. Antitachycardia pacing successfully terminated most episodes of ventricular tachycardia; in patients with this feature activated, it was used frequently but required reprogramming to achieve high levels of success.

Aged↗
PubMed1993

Conversion rates of induced versus spontaneous ventricular tachycardia by a third generation cardioverter defibrillator. The VENTAK PRx Phase I Investigators.

Seventy consecutive patients received the first VENTAK PRx pulse generators (Cardiac Pacemakers, Inc.) implanted in the United States. This multiprogrammable device has therapeutic options that include: (1) antitachycardia pacing; (2) low energy cardioversion; (3) defibrillation shocks; and (4) bradycardia pacing. There were 60 males and 10 females with a mean age of 65.3 +/- 9.4 years. The anatomical diagnoses were coronary artery disease in 55 patients, cardiomyopathy in 7 patients, congenital heart disease in 2 patients, and miscellaneous disease in the remaining 6 patients. Thirty-six percent had a history of sudden cardiac death and 90% had documented monomorphic ventricular tachycardia. The mean ejection fraction was 32.7% +/- 12.2%. Thirty-three (49.3%) had an ejection fraction < or = 30%. Electrophysiological testing was done preimplant, predischarge, and 1 to 2 months postimplant to define a specific electrical therapy and evaluate the efficacy of the device. Two hundred ninety-three of 367 (80%) episodes of induced ventricular tachycardia were successfully terminated by the VENTAK PRx programmed for antitachycardia pacing. There were 1,794 total therapy episodes for spontaneous ventricular tachycardia; 91% (1,641 episodes) were terminated by antitachycardia pacing and 153 episodes were converted by shocks during a minimal 6-month follow-up per patient. We conclude that documentation of a successful antitachycardia pacing modality in the electrophysiology laboratory predicts conversion of spontaneous episodes of ventricular tachycardia. Furthermore, antitachycardia pacing by the VENTAK PRx can terminate the majority of episodes of ventricular tachycardia.

Aged↗
PubMed1991

Effects of the angiotensin I converting enzyme inhibitor perindopril on cerebral blood flow in awake hypertensive rats.

As chronic hypertension shifts the lower limit of cerebral blood flow (CBF) autoregulation to higher pressure levels, we studied the effects of the angiotensin converting enzyme (ACE) inhibitor, perindopril on mean arterial pressure (mean BP), basal CBF, and CBF autoregulation in awake renovascular hypertensive (2 kidneys, 1 clip model) and spontaneously hypertensive rats (SHR). Blood pressure was measured via a chronically implanted arterial cannula and CBF by hydrogen clearance. Chronic renovascular hypertension, like spontaneous hypertension, caused a marked shift in the lower limit of CBF autoregulation but did not alter basal CBF. In SHR, acute administration of perindopril did not diminish CBF in spite of the fact that BP fell to a level below the lower limit of CBF autoregulation (determined by hypotensive hemorrhage). Chronic treatment of renovascular hypertensive rats with perindopril normalized BP and restored CBF autoregulation.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1991

Ninety-six episodes of spontaneous ventricular tachycardia in 1 week: success of ramp pacing by a pacer-cardioverter-defibrillator.

This case report describes the flexibility and usefulness of a pacer-cardioverter-defibrillator for the management of a 63-year-old patient with malignant ventricular tachyarrhythmias. Ninety of 96 episodes of ventricular tachycardia were terminated successfully with ramp pacing in a 1-week period. In those patients who have frequent episodes of ventricular tachycardia that respond to antitachycardia pacing, the multifunction device can add to the patient's comfort and increase acceptance of this type of device.

Cardiac Pacing, Artificial↗
PubMed1991

Long-term community hospital experience with the internal defibrillator.

Seventy-seven patients with drug refractory ventricular tachycardia (57) and ventricular fibrillation (20) received the implantable defibrillator. There were 55 men and 22 women with a mean age of 63 +/- 10 years. The anatomical diagnoses were coronary artery disease in 61 patients, cardiomyopathy in 15 patients, and aortic stenosis in one patient. The mean ejection fraction was 32 +/- 12%. Concurrent surgery at defibrillator implantation was coronary bypass in eight patients and aortic valve replacement in one patient. There were no intraoperative mortalities. The mean ventricular fibrillation termination threshold was 13 +/- 6 joules. During a follow-up period of 16 +/- 10 months (range 2-40 months) four patients died: electrical mechanical dissociation (two patients), respiratory failure, and sepsis. Thirty-eight patients (51%) continued receiving antiarrhythmic drug therapy, with quinidine sulfate and procainamide being the most frequently utilized agents. Fifty-four patients (72%) have received a mean of 9 +/- 10 shocks (range 1-44). Implantable defibrillators are often needed in patients seen in large community hospitals. This technology can be administered successfully in this setting with complications and results comparable to those reported from university hospitals. Implantable defibrillators are effective in preventing arrhythmic death and can be used with low risk to the patients.

Anti-Arrhythmia Agents↗
PubMed1991

A prospective study utilizing a transtelephonic electrocardiographic transmission program to manage patients in the first several months post-ICD implant.

We prospectively enrolled 20 consecutive patients (11 men and 9 women; mean age 63 +/- 9.5 years) post-AICD implant in a transtelephonic electrocardiographic transmission (TET) program. The monitor was chosen for its retrograde (30 seconds) and antegrade memory capabilities (45 seconds). The patients were discharged from the hospital after receiving instructions to utilize the system for any cardiac symptoms. The monitor was worn 1-3 months (mean 2.5 +/- 0.7 months). During the follow-up period there were 54 TETs received. Nine were for documented AICD discharges, 19 were for symptoms associated with arrhythmias (11 of these 19 reported AICD discharges that were not documented), and 26 for symptoms not associated with arrhythmias. Eight of the 9 AICD discharges documented were appropriate for ventricular tachycardia (mean 185 +/- 40 beats/min). The arrhythmias associated with symptoms were: atrial fibrillation (12); nonsustained ventricular tachycardia (3); ventricular couplets (2); ventricular premature beats (10); and atrial premature contractions (2). Several TETs documented multiple arrhythmias. The most common symptoms not associated with arrhythmias were shortness of breath, dizziness, chest pain, and nervousness. Office interrogation of the AICDs revealed 12 of the 20 patients (60%) had received AICD discharges, with 5 of these 12 patients unaware of this occurring. We found the TET monitoring system a useful tool in the management of the AICD patient the first several months postoperatively. We were able to assess device function and avoid unnecessary office visits and/or hospitalizations.

Atrial Fibrillation↗
PubMed1990

Chronic treatment with the angiotensin I converting enzyme inhibitor, perindopril, restores the lower limit of autoregulation of cerebral blood flow in the awake renovascular hypertensive rat.

Chronic hypertension shifts the lower limit of cerebral blood flow autoregulation to a higher pressure level. Although acute administration of angiotensin converting enzyme inhibitors restores the lower limit of cerebral blood flow autoregulation the chronic effects have not received much attention. We studied the effect of the angiotensin converting enzyme inhibitor, perindopril, on mean arterial pressure, basal cerebral blood flow and cerebral blood flow autoregulation in renovascular hypertensive (two-kidney, one clip model) and normotensive male Wistar rats. Seven weeks after renal artery clipping or sham operation rats received daily intraperitoneal injections of perindopril. The dose was increased from 1 to 8 mg/kg over the first 4 weeks until blood pressure was normalized. Chronic renovascular hypertension caused a marked shift in the lower limit of cerebral blood flow autoregulation but did not alter basal cerebral blood flow. Treatment of hypertensive rats with perindopril normalized blood pressure and restored cerebral blood flow autoregulation. Chronic treatment of normotensive rats with perindopril increased basal cerebral blood flow. In conclusion, chronic treatment of renovascular hypertensive rats with perindopril causes a shift in the lower limit of cerebral blood flow autoregulation towards the value observed in normotensive rats.

Angiotensin-Converting Enzyme Inhibitors↗