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Biomedical subjects

R Vincent

Publications and source records attributed to R Vincent.

At least 127 records · Page 7Linked to original sources
PubMed1987

Transvenous cardioversion for the management of recurrent ventricular arrhythmias.

The efficacy of transvenous cardioversion and defibrillation for treating life threatening spontaneous ventricular arrhythmias was assessed in a study of 17 patients in a cardiac care unit. Eleven had ventricular tachycardia, five had ventricular fibrillation, and one had both. Transvenous cardioversion successfully terminated tachyarrhythmias on 42 separate occasions in ten patients. Stable electrode positions could not be achieved in two patients, recurrent late displacement occurred in one, and four patients had no further arrhythmias requiring cardioversion once the lead was placed. The energy levels required for successful cardioversion ranged from 0.05 J to 25 J for ventricular tachycardia and from 1 J to 25 J for ventricular fibrillation. The nine successful shocks of 1 J or less did not require sedation or general anaesthesia. High energy (25 J) endocardial shocks were unsuccessful in terminating arrhythmias in two patients, one with ventricular tachycardia and the other with both ventricular tachycardia and fibrillation. Minor unwanted effects of endocardial shocks occurred in five patients. These were acceleration of ventricular tachycardia in two patients and complications of pacing via the special lead in three others: failure of sensing occurred in all three and one patient also had a transient rise in pacing threshold. A postmortem examination in one patient who had received three unsuccessful high energy shocks revealed localised endocardial necrosis at the site of the distal electrode. Transvenous cardioversion offers advantages over external cardioversion but at present practical difficulties limit its application to patients with recurrent ventricular arrhythmias that cannot readily be controlled by conventional methods.

Aged↗
PubMed1987

Plasma free fatty acid profile in male and female domestic fowl at rest and after exercise.

The concentration and profile of the plasma free fatty acid (FFA) pool was determined in three male and three female domestic fowl before and after a 70 min treadmill run. The fatty acid profile of total food lipids was also determined. At rest, palmitic, stearic oleic, and linoleic acids were the main individual fatty acids in the plasma FFA pool and together constituted 50 to 60% of the total. Shorter chain fatty acids (C10 to C15) made up 24 to 38% of the total. In food lipids C16 and C18 fatty acids constituted more than 95% of total fatty acids, therefore food was not a significant direct source of short chain (less than C16) fatty acids. After exercise, there was an 8 to 10 fold increase in plasma FFA concentration. The proportion of lower chain (less than C16) FFA decreased and the proportion of C16 and C18 FFA, in particular oleic acid, increased. At the end of exercise the profile of the plasma FFA pool was similar to that of the adipose tissue triglyceride. Release of fatty acids from adipose tissue may be a major influence on exercise-induced changes in the plasma FFA profile.

Animals↗
PubMed1986

Treatment of acute myocardial infarction with anisoylated plasminogen streptokinase activator complex.

A controlled trial in 149 patients admitted to a district hospital with probable myocardial infarction tested the effect of 30 units of anisoylated plasminogen streptokinase activator complex (APSAC) on indices of infarct size. Patients were grouped prospectively according to whether they entered the trial within two and a half hours (early entry) or between two and a half and four hours (late entry) after onset of the symptoms. Sixty seven of 73 patients in the control group showed increased plasma activity of myocardial creatine kinase isoenzyme that was diagnostic of infarction compared with only 60 of 76 who received APSAC. The difference was significant overall but occurred predominantly in the early entry group. The patients who received APSAC had more early ventricular arrhythmias, compatible with reperfusion, and showed greater preservation of R waves during admission to hospital. Unwanted effects were generally minor and more common in the actively managed group than the control group (26% v 3%). After nine to 12 months of follow up 12 patients in the control group had died compared with seven in the actively managed group. The ease of administration and the apparent efficacy of APSAC suggest that it is suitable for use in a district hospital for patients with suspected acute myocardial infarction.

Anistreplase↗
PubMed1985

Simple mechanical methods for cardioversion: defence of the precordial thump and cough version.

A prospective study was made of the value of the precordial thump and of cough version in life threatening ventricular arrhythmias. Of about 5000 medical and surgical patients, 68 were treated for persistent ventricular tachycardia and 248 for ventricular fibrillation, 86 of whom had presented outside hospital. Mechanical intervention was successful in 26 incidents occurring in 23 patients. Electrocardiographic records were obtained in 14 instances. Ventricular fibrillation was terminated by a thump in five patients and ventricular tachycardia by either a thump or a cough in a total of 17 patients. Four additional instances were recorded of successful recovery from asystolic or unspecified circulatory arrest after a precordial thump. Fifteen patients survived to be discharged from hospital. The potential benefit of the precordial thump and cough versions greatly outweighs their risks; hence these manoeuvres should probably be reintroduced into schedules for first aid resuscitation.

Aged↗
PubMed1985

Artefactual ST segment abnormalities due to electrocardiograph design.

Specifications recommended for electrocardiographs omit any reference to phase characteristics and place undue emphasis on an extended amplitude response. This does not, however, ensure faithful reproduction of the electrocardiogram and may result in less effective attenuation of unwanted noise than can be achieved with modern filters. The separate effects of phase and amplitude response on electrocardiographic signals were compared, and it was shown that distortion of the electrocardiogram by equipment with an inadequate phase response may cause changes resembling those seen in ischaemic heart disease. Case reports are presented in which distortion produced by commercial equipment impeded diagnosis. Specifications recommended as standard for electrocardiographs should be modified to include phase response and allow greater attenuation of frequencies below 0.5 Hz.

Adult↗
PubMed1984

A community training scheme in cardiopulmonary resuscitation.

Community instruction in basic life support and resuscitation techniques has been offered in Brighton Health District since 1978. Classes are held frequently for the general public and businesses, schools, and other organisations. First aid care for unconscious patients, the treatment of respiratory obstruction or failure, and the recognition and management of cardiac arrest is taught in a single two hour session. Over 20 000 people have been taught, up to 40 at a time in multiple groups of six to eight, by lay instructors usually supervised by ambulancemen trained to "paramedic" standards. Fifty four incidents have been reported to us in which techniques learnt in the classes have been implemented. Five patients recovered after first aid support but subsequently did not seek medical treatment. Of the 34 patients reviewed in hospital, at least 20 survived to be discharged. We believe that intervention may have been life saving in 16 instances. The benefit of cardiopulmonary resuscitation for victims who may have been asystolic is, however, difficult to quantify because the outcome without intervention cannot be predicted accurately. Community training in basic life support should be considered in association with ambulances equipped for resuscitation and hospital intensive care and cardiac care units as an integrated service for the victims of sudden circulatory or respiratory emergencies. The results achieved so far in Brighton and in other more advanced schemes, particularly in the United States of America, may encourage other health authorities to adopt similar programmes.

Adolescent↗
PubMed1984

Adjustment of the osmolality of Percoll for the isopycnic separation of cells and cell organelles.

The addition of 1 part of 1.5 M NaCl or 2.5 M sucrose (10 X concentrate) to 9 parts of Percoll produces a stock solution that is hypertonic (350-360 mOsm/kg H2O). Because the osmolality is a critical variable in the isopycnic separation of cells and cell organelles, the factors accountable for this hypertonicity were investigated. Percoll, a colloidal suspension of silica particles coated with polyvinylpyrrolidone, can be described as a medium composed of two distinct compartments, an aqueous phase and a solid phase. According to this model, solutes (e.g., NaCl, sucrose) should have access to the aqueous phase and add to the intrinsic osmolality of Percoll, but should be excluded from the solid phase. In order to verify this hypothesis, mathematical equations were derived and tested. It was found that the ratio of the aqueous volume to the total volume of Percoll (R value) was dependent on the ionic strength of the stock solution. With this parameter, the osmolality of Percoll stock solutions could be predicted (+/-2%) and, consequently, one could calculate the proper dilution to be used with saline, culture medium, or sucrose concentrates to obtain a truly isotonic Percoll stock solution (congruent to 290 mOsm/kg H2O). The relative importance of an accurate control of the osmolality in the preparation of density gradients made up of Percoll is also discussed.

Cell Fractionation↗
PubMed1984

Automated external defibrillation: laboratory evaluation.

Twelve samples of ventricular fibrillation were fed into nine automated external defibrillator-pacemakers ( AEDP , "Heart Aid") of recent design. All the devices recognised and defibrillated ventricular fibrillation in seven of the samples within 30 sec. None of the devices reacted to two of the samples; in the remaining three there was inter-device variation ranging from an appropriate response to no response, as well as inappropriate pacing or delay in recognition and treatment. Poor recognition of some ventricular fibrillation waveforms with considerable inter-device variation limits the usefulness of this model. A new prototype responded more consistently and future models may be of value in community resuscitation. The difficulty of evaluating the diagnostic capability of AEDP devices in clinical use makes comprehensive laboratory testing essential prior to release.

Electric Countershock↗
PubMed1984

Single lead atrial synchronised pacing in patients with cardiogenic shock after acute myocardial infarction.

A pacing system requiring only a single lead was used to establish atrial synchronised pacing in eight patients with complete atrioventricular block and cardiogenic shock following acute myocardial infarction. Spontaneous atrial activity was sensed through electrodes positioned on the pacing lead and used to trigger ventricular demand pacing. A normal atrioventricular relation could be established in each of these critically ill patients without the complexity of inserting and finding a stable position for an additional atrial sensing lead. Atrial synchronised pacing at the spontaneous sinus rate had distinct haemodynamic advantages compared with conventional ventricular pacing at 100 beats/min. Mean cardiac output for the group was 3.3 1/min with atrial synchronised pacing compared with 2.6 1/min with conventional pacing, a significant difference of 27%. Peak systolic pressure averaged respectively 91 and 73 mm Hg in the two pacing modes. With conventional ventricular pacing a pronounced phasic alteration in blood pressure was observed, dependent on the altering relation of the paced beats to spontaneous atrial activity. Atrial synchronised pacing abolished this effect and resulted in a stable blood pressure at or above the peak pressure achieved with conventional pacing. Atrial synchronised pacing with a single lead system can be established rapidly. This mode of pacing has appreciable and significant haemodynamic superiority over conventional ventricular pacing in patients with cardiogenic shock and atrioventricular block following acute myocardial infarction.

Aged↗
PubMed1984

Combined receptor intervention and myocardial infarction.

The aims of treatment in acute myocardial infarction are to limit evolving muscle necrosis, prevent heart failure, maintain electrical stability, and preserve the coronary circulation to avoid progressive or recurrent infarction. No single treatment achieves all these objectives. The rationale for the use of adrenoceptor blocking drugs is that they will oppose the effects of the increased sympathomimetic activity which follows acute infarction and which may adversely affect outcome. More is known of the clinical use of pure beta-blockade than of combined alpha- and beta-blockade with labetalol but in theory combined receptor blockade will produce additional beneficial effects over beta-blockade alone. beta-Adrenoceptor antagonists have a theoretical role in limiting infarct size. They may reduce the oxygen deficit of jeopardised though potentially viable tissue, limiting infarct size by their favourable effect on heart rate, systolic pressure, contractility, and metabolic pathways. That beta-blockade reduces myocardial damage has been confirmed in animal studies. Studies in man using enzyme release or R wave scoring as indicators of infarct size also suggest that oral or intravenous beta-blockers after infarction encourage myocardial salvage. Few studies have been reported in which the effects of combined alpha- and beta-blockade on infarct size have been determined. The actions of a dual blocking agent are more complex and the outcome less predictable than from beta-blockade alone: the advantages of the beta-blocking component will be retained while the alpha-blocking component may conceivably further diminish oxygen demand by reducing systolic pressure and heart size. Less favourably, coronary perfusion pressure may also fall. It is apparent that further clinical studies are needed. Adrenergic blockade may be used to prevent or treat ventricular arrhythmias which develop after infarction in the face of heightened sympathetic tone and continued ischaemia. Clinical and experimental evidence points to the efficacy of beta-blockade in ischaemia-related arrhythmias, but beta-blockade alone is probably ineffective against arrhythmias arising during reperfusion. In experimental studies, alpha-blockers are effective against both forms of arrhythmia although the doses required for reperfusion effects may produce unacceptable hypotension in clinical use. It is possible that combined alpha- and beta-blockade may have broader antiarrhythmic activity than beta-blockers alone but present clinical data on the value of labetalol in controlling postinfarction arrhythmias are sparse.(ABSTRACT TRUNCATED AT 400 WORDS)

Adrenergic alpha-Antagonists↗
PubMed1983

[Crises in adolescence. Value of a specialized hospitalization unit].

Hospitalization of a disturbed adolescent is not necessarily a distressing experience. It may provide the opportunity for the separation-individuation process to develop. The various possibilities offered by the Adolescent Psychiatric Unit at the Salpêtrière Hospital are described. The outcome of hospitalization is often gradual autonomy of the adolescent in his family. The functioning of the Unit is illustrated by three clinical reports.

Adolescent↗
PubMed1983

Five hundred patients with myocardial infarction monitored within one hour of symptoms.

Of 2886 patients monitored during acute myocardial infarction, 500 were observed within one hour of the onset of symptoms. Half of the early admission group were admitted in response to emergency 999 calls and 435 of them travelled in resuscitation ambulances, where surveillance for arrhythmias was instituted. Pulmonary oedema occurred in 130 patients (26%), cardiogenic shock supervened in 60 (12%), and 115 (23%) died in hospital. Ventricular fibrillation was observed in 98 patients (20%). Forty two of them survived to be discharged, including 20 of the 24 with primary fibrillation which had occurred first in hospital. In only one case did primary ventricular fibrillation occur after the first 10 hours of onset of illness. Sinus bradycardia, atrial fibrillation, ventricular tachycardia, and ventricular fibrillation were all observed more frequently in patients admitted within one hour after the onset of symptoms than in those admitted later. An element of selection is inevitable when early admission is encouraged by the existence of a resuscitation ambulance system; this will depend in part on the early recognition of risk and the geographical location of the attack. These factors may bias the group towards relatively high risk. Nevertheless, prompt admission after myocardial infarction should improve survival by permitting successful management both of ventricular fibrillation and of other arrhythmias which may influence short term and long term prognosis.

Aged↗
PubMed1983

A micromethod for the quantitation of cellular proteins in Percoll with the Coomassie brilliant blue dye-binding assay.

A simple procedure for the determination of cellular proteins in Percoll-containing samples is described. Percoll precipitated when particulate proteins were solubilized by dilution of the samples in a NaOH-Triton X-100 mixture. After centrifugation at high speed (12,000g), the supernatant was assayed for proteins with the Coomassie brilliant blue dye-binding assay. With an automatic spectrophotometer, 50-microliter aliquots gave a linear response between 0 and 3 micrograms of bovine serum albumin. After a fivefold dilution in the alkali-detergent mixture, proteins in samples containing up to at least 60% Percoll can be accurately quantitated on a standard curve prepared in the absence of Percoll. Because the sensitivity of the assay was better than 100 ng, the procedure outlined in this paper can also be used as a general protein micromethod.

Animals↗