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Biomedical subjects

A F Mackintosh

Publications and source records attributed to A F Mackintosh.

At least 19 recordsLinked to original sources
PubMed1997

Late, intermittent obstruction of a mitral prosthesis by chordal remnants.

A 59 year old male was admitted 10 weeks following insertion of a Medtronic Hall mitral prosthesis. He suffered recurrent episodes of electromechanical dissociation (EMD). Transthoracic echocardiography demonstrated that during the times of haemodynamic compromise, the mitral prosthesis was intermittently obstructed. Emergency surgical intervention revealed that chordae tendineae had prolapsed through the lesser orifice, obstructing the valve mechanism. The mitral remnants were excised, and as the valve functioned normally, it was not replaced. Postoperatively, the patient made an uneventful recovery. This case illustrates the Doppler echocardiographic features associated with extrinsic obstruction of a mitral prosthesis, and demonstrates that this unusual complication can be responsible for late valve dysfunction.

Chordae Tendineae↗
PubMed1994

Automatic recording and timing of defibrillation on general wards by day and night.

To measure the speed of response to ventricular fibrillation on general medical wards and to assess the importance of this and other factors for survival to leave hospital, 69 consecutive patients with ventricular fibrillation were studied prospectively using an automatic timing device in the hospital telephone exchange and an automatic timer and ECG recording during resuscitation. Twenty-seven patients were initially resuscitated and 17 were discharged from hospital. The median time to connect the monitor after recognition of a cardiac arrest was 127 s (range 0-277) for survivors and 132.5 s (range 0-620) for non-survivors. The median time ventricular fibrillation was displayed before the first shock was 43 s (range 4-75) for survivors and 52 s (range 10-454) for non-survivors. These differences were not significant; but logistic regression analysis identified primary ventricular fibrillation, short display time (logged data), 'early' time of day, absence of pre-existing non-cardiac illness, and post-defibrillation heart-rate > 30 beats.min-1 in rank order as independent predictors of survival. In spite of no significant diurnal variation in response time, successful resuscitations were concentrated in the early nursing shift (0730-1530 h). Four shocks were inappropriate. Clinical diagnosis was more predictive of outcome than the time to the first shock. The reasons for the poorer results in the evening and night are uncertain.

Aged↗
PubMed1991

The Acute Infarction Ramipril Efficacy (AIRE) Study: rationale, design, organization, and outcome definitions.

The rationale, design, organization, and outcome definitions of the Acute Infarction Ramipril Efficacy (AIRE) Study are described prospectively. A total of 2,000 patients (1,000 per treatment group) will be recruited to this multicenter, multinational, double-blind, randomized, placebo-controlled study investigating the effect of oral treatment with ramipril (2.5 or 5 mg twice daily) on the total mortality of survivors of an acute myocardial infarction (AMI) with early clinical evidence of heart failure. Secondary outcomes of the study include progression to severe/resistant heart failure (at which time the patient will be withdrawn from the study treatment), reinfarction, and stroke. Treatment will be initiated in hospital between day 3 and day 10 following AMI, and follow-up continued for an average of 15 months and a minimum of 6 months. The study data will be analyzed on an intention-to-treat basis: a single formal interim analysis will be conducted after 175 deaths. An Independent Adjudicating Panel will act as the overall ethical supervisory body for the study and will retain the randomization code. An International Steering Committee will be responsible for the clinical definitions of the secondary study outcomes, and will regularly review progress of the study. We believe that early treatment with ramipril may reduce the total mortality of patients surviving an AMI with clinical evidence of heart failure.

Acute Disease↗
PubMed1990

Resuscitation of patients with cardiac arrest by ambulance staff with extended training in West Yorkshire.

OBJECTIVE: To investigate the results of resuscitation of patients with cardiac arrest by ambulance staff with extended training in West Yorkshire. DESIGN: Study of all such attempts at resuscitation over 32 months, based on the standard report form for each call made by the ambulance staff and the electrocardiogram that showed the initial rhythm in each patient. SETTING: Area covered by West Yorkshire ambulance service. SUBJECTS: 1196 Patients with cardiac arrests attended by 29 ambulance staff with extended training. MAIN OUTCOME MEASURE: Result of resuscitation. RESULTS: The initial rhythm was asystole or electromechanical dissociation in 740 patients and ventricular fibrillation in 456 patients; overall 65 patients survived to be discharged from hospital. Sixty four of the 456 patients in whom ventricular fibrillation was the initial rhythm recorded, and 46 in whom ventricular fibrillation persisted after the ambulance staff arrived, survived. Only one of the 740 patients who initially had asystole or electromechanical dissociation survived. Factors associated with a greater chance of ventricular fibrillation occurring were: age less than 71, the arrest being witnessed by a bystander, resuscitation by a bystander, the arrest occurring in a public place, and a response time by the ambulance staff of less than six minutes. For patients found in ventricular fibrillation a shorter response time was associated with improved survival but resuscitation by a bystander was not. Additional skills learnt during extended training were used for 51 of the 65 patients who survived. CONCLUSIONS: Ambulance staff with extended training can save the lives of patients with cardiac arrest due to fibrillation, though asystole and electromechanical dissociation have a poor prognosis and should perhaps receive little attention during extended training.

Age Factors↗
PubMed1986

The effect of indoramin on exercise performance in mild hypertension.

The alpha 1-adrenoceptor antagonist indoramin is proposed to reduce arterial blood pressure without a concomitantly significant increase in heart rate (HR). The present study involves assessment of the effect of alpha 1-adrenoceptor antagonism in patients with mild hypertension on the HR/oxygen consumption (Vo2) relationship, which has previously been shown to indicate improvement in cardiorespiratory fitness following exercise training. A total of 16 patients with a systolic blood pressure of 140-200 mm Hg and diastolic blood pressure of 95-110 mm Hg were examined. A double-blind, placebo-controlled study design was utilized. Following initial observations, the patients were randomized into one group (a) of seven patients who were given a placebo, indoramin, and finally placebo, and a second group (b) of nine patients who were given the two agents in the reverse order, i.e., indoramin, placebo, indoramin; each intervention lasted for 2 weeks and indoramin was given in a dose of 75 mg/day. Indoramin caused a reduction in the elevation of the computed regression line relating HR to Vo2 (a shift to the right), such that at the same HR a greater Vo2 was attained in 11 of the 16 patients in comparison with the baseline exercise test. Pooled results showed a shift of the HR/Vo2 regression line to the right when indoramin was compared with baseline (p less than 0.05) or placebo. In the same patients, indoramin caused a decrease in arterial blood pressure during exercise relative to baseline or placebo periods, and a decrease in the HR during exercise relative to baseline period, but not when compared with placebo periods.(ABSTRACT TRUNCATED AT 250 WORDS)

Clinical Trials as Topic↗
PubMed1986

Oral xamoterol in patients with sinoatrial disease.

Twelve patients with sinoatrial disease were assessed while on oral xamoterol (200 mg twice daily) and placebo by a double blind randomised, crossover trial that lasted four weeks. Nine of the patients had been referred for permanent pacing. Xamoterol produced favourable changes in the number of pauses and the mean heart rate in six patients. Another patient deteriorated on xamoterol. Six patients were started on long term xamoterol. Xamoterol produces short term electrocardiographic improvement in some, but not all, patients with symptomatic sinoatrial disease.

Adrenergic beta-Agonists↗
PubMed1982

Sinus node function in first three weeks after cardiac transplantation.

Donor sinus node function was studied in 10 patients from day 4 to day 24 after cardiac transplantation. Cycle length, atrial arrhythmias, corrected sinus node recovery time, and estimated sinoatrial conduction time were recorded daily. Five patients had at least two sets of results suggesting sinus node dysfunction (group A) while five patients had no such abnormalities (group B). The prognosis in group A was poor, with four of the five patients dying within four months of the operation; one unexpected death from arrhythmias was recorded by ambulatory electrocardiographic monitoring. All five patients in group B survived for at least eight months. In nine patients sinus node function varied from day to day, with corrected sinus node recovery time reaching a peak at 11 to 18 days after operation. The longest corrected sinus node recovery time was 11 160 ms. Neither the differences between the patients, nor the day to day variation, could be explained solely by the degree of rejection as assessed by biopsy or by the ischaemia time of the heart during procurement. Sinus node dysfunction soon after transplantation is associated with a poorer prognosis and might be the terminal event in some cases.

Adult↗
PubMed1981

Sinuatrial disease in young people.

A survey at three cardiac centres disclosed nine patients under the age of 25 years with sinus node dysfunction in the absence of other forms of heart disease. All were male and seven were above the 90th centile for height. Ambulatory monitoring was performed on all the first-degree relatives of six of the patients and three families showed conducting system disturbances in the form of sinuatrial disorders or delayed atrioventricular conduction. A genetic factor may be involved in the aetiology of sinuatrial disease in young people.

Adolescent↗
PubMed1981

Cardiac damage presenting late after road accidents.

Six examples of cardiac damage secondary to non-penetrating trauma in road accidents are described. In all six cases the lesion was not recognised at the time of the accident but became clinically important two days to 17 years later. As the patients were young or had unusual lesions, the damage could be attributed to the accident. In older patients with common cardiac problems the trauma might not be recognised as the underlying cause.

Accidents, Traffic↗
PubMed1980

A flexible signal-averaging system for cardiac waveforms.

The repetitive nature of cardiac waveforms renders them suitable for processing by signal averaging. A flexible system is described, based on a general-purpose digital computer, capable of averaging a variety of cardiac signals in excess of 0.5 microV containing frequency components below a theoretical Nyquist limit of 5 kHz. Important features of the system include real-time processing capability at a high level of interactive control, and the facility to trigger the averaging process accurately from any part of either the data or a synchronous reference waveform. Application of the system to electrocardiographic and phonocardiographic signals at conventional gain has enabled clinically useful records to be obtained in the face of obtrusive environmental noise. The averaging of signals of a similar nature after considerably increased amplification has revealed cardiac activity unseen in conventional records in a total of 81 subjects.

Analog-Digital Conversion↗
PubMed1979

Hospital resuscitation from ventricular fibrillation in Brighton.

The overall results over three and a half years of the treatment of ventricular fibrillation secondary to ischaemic heart disease in the Royal Sussex County Hospital were reviewed. Records of all patients who were brought to hospital by resuscitation ambulances or who were admitted to the coronary care unit from any source were analysed. Eighty-seven of the 174 patients (50%) who developed ventricular fibrillation were discharged. The survivors included 13 out of 61 patients (21%) in whom fibrillation was secondary to cardiogenic shock or severe left ventricular failure. The presence of resuscitation equipment and nursing staff trained to use it in the general wards and emergency areas ensured a uniformly high success rate throughout the hospital, similar to that achieved in the coronary care unit. Prompt defibrillation in the general wards and the accident and emergency department may improve overall survival.

Adult↗