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Biomedical subjects

R A Greenbaum

Publications and source records attributed to R A Greenbaum.

14 recordsLinked to original sources
PubMed1997

Towards a comprehensive telecardiology monitoring centre for community-based services.

In a pilot study of primary-care telecardiology, 2563 consultations were carried out over 18 months. Following teleconsultation, 2076 patients (81%) were found to be suitable for management entirely by the general practitioner, without the need for referral to hospital. The system identified 487 patients (19%) with cardiac problems who required either admission to hospital or outpatient assessment. There was a resultant saving of referrals to hospital accident and emergency departments. Extension of the telecardiology service to include tele-echocardiography may result in faster access to diagnosis and better management of patients in heart failure, improving patients' quality of life and reducing hospitalization.

Cardiology↗
PubMed1996

Telecardiology: supporting the decision-making process in general practice.

To assess the initial phase of a telecardiology diagnostic service for general practitioners (GPs), we provided 93 GPs in 26 health centres with direct telephone access to a cardiologist, and equipped them with hand-held, automatic standard 12-lead electrocardiogram (ECG) transmitters for on-line cardiac consultations and ECG interpretation in their daily practice. Clinical details, reason for consultation and the ECG signal were transmitted from the GPs' practices or the patients' homes. A consultation followed and a full report, including ECG print-out, was then sent to the GP. During an 18-month study period, 2563 consultations were carried out. The system allowed the identification of 479 patients (19%) with urgent cardiac problems and the remaining 2084 (81%) in whom admission or outpatient investigation was unnecessary. Following the study, we distributed a questionnaire asking the GPs to rate the quality, define the use and consider the benefit of the service to their daily practice. We conclude that a telecardiology diagnosis and ECG interpretation service is simple, reliable and efficacious in routine primary care. It offers instant access to cardiac assessment and supports the decision-making process of GPs. A preliminary cost comparison with a conventional referral indicated that a teleconsultation was substantially cheaper. We expect that the future incorporation of teleechocardiography would expand the scope of telecardiology even further and allow comprehensive cardiology consultations.

Cardiology↗
PubMed1995

Reduced in-hospital mortality from acute myocardial infarction with general adoption of thrombolytic treatment in the North West Thames health region 1979-1991.

OBJECTIVE: To determine the impact of studies of thrombolytic treatment in acute myocardial infarction on inhospital mortality. DESIGN: Retrospective study. SETTING: All 21 major hospitals in the North West Thames health region. PATIENTS: 63,903 patients with acute myocardial infarction. STUDY PERIOD: 1979-1991. MAIN OUTCOME MEASURES: in-hospital mortality. RESULTS: Overall mortality decreased by 5.2% from 25.4% to 20.2% (P < 0.0001) (95% confidence interval (CI) 3.4 to 6.6). Male mortality decreased by 6.5% from 22.3% to 15.8% (P < 0.0001) (95% CI 4.8 to 8.4); female mortality decreased by 4.3% from 32.6% to 28.3% (P < 0.01) (95% CI 1.3 to 7.4). Reductions in mortality occurred in all age and sex groups but were greater in younger patients. Logistic regression analysis of death rates showed that the odds ratio of death in 1991 compared with that in 1979 was 0.75 (95% CI 0.69 to 0.82). After allowing for the effects of age and sex, this odds ratio became 0.54 (95% CI 0.49 to 0.59), as more elderly patients were treated in 1991. Purchase of streptokinase increased 31-fold from 116 doses in 1983 to 3554 doses in 1991. There was a pronounced negative association between annual purchases of streptokinase and mortality (Kendall's rank correlation = -0.86, P = 0.003). Changes in clinical practice resulted in the saving of the lives of an estimated 600 patients with acute myocardial infarction in 1991. This extrapolates to an annual saving of 10,500 lives in the United Kingdom. CONCLUSIONS: In the past few years thrombolytic treatment has been widely adopted for the management of acute myocardial infarction. This has been paralleled by a substantial reduction in in-hospital mortality.

Adult↗
PubMed1993

Relationship between myocardial collagen and echo amplitude in non-fibrotic hearts.

The aim of the study was to investigate the relationship between myocardial collagen and regional echo amplitude in humans with non-fibrotic myocardium. The ratio of myocardial collagen to total myocardial protein was determined as the hydroxyproline/leucine ratio in endomyocardial biopsies obtained from the right ventricular side of the interventricular septum in orthotopically transplanted hearts. Regional echo amplitude was measured in the interventricular septum. Patients were studied prospectively. Twenty-five patients (five female, 20 male) who had undergone orthotopic cardiac transplantation were studied 355 to 2939 days (1009 +/- 718, mean +/- SD) post-transplantation at the time of annual cardiac catheterization and endomyocardial biopsy. Patient ages varied from 22 to 62 years (46 +/- 11). Donor ages were 14 to 47 years (25 +/- 8) and the ischaemic time, 90 to 245 min (151 +/- 42). Cardiac transplantation was performed for end-stage cardiac failure in all patients. The aetiology of cardiac failure was valvular heart disease in three, dilated cardiomyopathy in eight and ischaemic heart disease in the remainder. Echo amplitude studies were performed within 24 h of endomyocardial biopsy. All but one patient were on an immunosuppressive regime consisting of cyclosporine A and azathioprine with additional steroids in three. The remaining patient, who was the longest surviving patient in the study group, had never been treated with cyclosporine. This patient was maintained on steroids and azathioprine alone. No patient had clinical or histological evidence for acute cardiac rejection and all were clinically well. Five patients had angiographic evidence of coronary artery disease. All subject studies were performed at Harefield Hospital.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

Haemodynamic effects of DPI 201-106, following single intravenous dose administration to patients with moderate cardiac failure.

DPI 201-106 is a novel compound unrelated to other cardioactive agents and has been shown to have an inotropic effect in animal preparations. The drug was given by intravenous infusion (20 mg over 10 min) to 10 patients with moderate cardiac failure and the haemodynamic effects measured at intervals up to 1 h following infusion. Maximal effects were seen immediately following the infusion of DPI 201-106. Cardiac index showed an increase from baseline 2.72 (0.16) 1 min-1 m-2 to 3.18 (0.21) 1 min-1 m-2 at the end of infusion (P less than 0.001). Subsequent values were not significantly raised. Pulmonary capillary wedge pressure and pulmonary artery pressure fell from 27.6 (3.2) and 36.9 (4.4) to 15.3 (3.6) and 24.2 (4.9) mmHg, respectively (P less than 0.001 in both cases). A statistically significant effect on cardiac index was not seen at 1 h. However, pulmonary pressures remained reduced at this point. Radionuclide ejection fraction showed a significant increase from 15.4 (1.5) to 21.9 (2.2)% (P less than 0.005) at the end of infusion, and maintained a significant increase at 1 h. Having demonstrated beneficial, acute haemodynamic effects in this study, further work should be undertaken with DPI 201-106 to investigate the effect of chronic treatment in patients with cardiac failure.

Adult↗
PubMed1988

Correction of left ventricular asynchrony by coronary artery surgery.

To investigate the effect of coronary artery bypass grafting on the timing of regional left ventricular wall motion, contrast left ventriculograms from 27 patients were digitised frame by frame before and after operation. End diastolic and end systolic volumes, ejection fraction, and peak ejection and filling rates showed no significant change. The commonest preoperative abnormality was delayed onset of inward wall motion during ejection, which was present in 14 patients over 10% (range 5-40%) of the cavity outline, leading to a pattern of "diagonal contours". After operation this pattern had resolved completely in 12 patients and partially in two. Minor abnormalities appeared postoperatively in five but overall the mean (1SD) area affected was reduced by 5 (8)%. The time span between the onset of inward motion in different regions of the cavity also fell significantly after surgery from 190 (50) to 130 (50) ms. Regional hypokinesis (6 cases) and abnormal wall motion during isovolumic contraction (4 cases) or isovolumic relaxation (5 cases) were not consistently affected. Thus successful coronary artery surgery is without consistent effect on overall left ventricular function, overall hypokinesis, or abnormal wall motion during the isovolumic periods. It does, however, strikingly reduce the asynchrony of wall motion during ejection, suggesting that before operation this abnormality may directly reflect impaired coronary blood flow. The results emphasise the potential value of analysing regional wall motion to elucidate functional abnormalities associated with coronary artery disease.

Adult↗
PubMed1987

Effect of heparin and contrast medium on platelet function during routine cardiac catheterisation.

Platelet function was studied during coronary angiography of patients complaining of chest pain. The following changes occurred 5 min after injecting 100 IU.kg-1 body weight of a conventional high molecular weight heparin: (a) a significant fall in platelet count; (b) a significant enhancement of platelet aggregation in platelet rich plasma (turbidometric technique) and in whole blood (platelet aggregation technique); and (c) significantly enhanced release of platelet thromboxane A2, a vasoconstrictor. These changes tended to reverse towards baseline values 5 min after injecting a contrast medium (Conray 420), which was found to inhibit platelet aggregation. Thus heparinisation with a high molecular weight heparin seems to cause pronounced activation of platelets in patients undergoing coronary angiography, and this may contribute to the pathogenesis of cardiac ischaemia that may occur during this procedure. Since coronary artery bypass surgery in similar patients involves the use of heparin at much higher doses without the concomitant use of an antiaggregatory contrast medium, it is possible that platelet hyperaggregability may contribute to the well documented ischaemic brain injury associated with this form of surgery. Furthermore, the use of high molecular weight heparin after successful coronary angioplasty or thrombosis may influence the incidence of reocclusion. These findings therefore suggest that low molecular weight heparinoids should be evaluated in these situations since these anticoagulants are only weak activators of platelet aggregation.

Adult↗
PubMed1987

Experience with nalbuphine, a new opioid analgesic, in acute myocardial infarction.

A total of 141 patients admitted to hospital with a diagnosis of suspected myocardial infarction were randomized to treatment with intravenous diamorphine (71) or nalbuphine (70). Myocardial infarction was subsequently confirmed in 109 patients. Both drugs provided good analgesia. Heart rate, blood pressure, respiratory rate, peak flow and minute volume were measured over a three-hour study period. Except for a slight fall in systolic blood pressure in the nalbuphine-treated group, there were no statistically significant differences between the groups. The nalbuphine-treated group had higher levels of aspartate aminotransferase and hydroxybutyric acid dehydrogenase but not creatine phosphokinase. The haemodynamic outcome and mortality at three months of the two groups were similar. It is concluded that nalbuphine provides effective analgesia coupled with few adverse circulatory or respiratory effects.

Analgesics↗
PubMed1986

The acute haemodynamic effects of nicardipine in patients with chronic left ventricular failure.

Nicardipine is a new slow channel calcium blocker. It has been shown to be effective in the treatment of hypertension and angina pectoris. Nine patients with mild to moderate left ventricular failure were given intravenous infusions of nicardipine and the haemodynamic effects measured. In patients receiving 20 mg of nicardipine, mean cardiac index rose to a peak 1.81 X min-1 X m-2 (64%) above the preinfusion level, stroke volume index rose by 12 ml X m-2 (35%) and heart rate rose by 16 beats X min-1 (20%). There was a significant fall in systemic vascular resistance of 50% manifested by a reduction of 22 mm Hg in systolic blood pressure (18%) and 18 mm Hg in diastolic blood pressure (22%). Pulmonary vascular resistance fell by 45%. Mean pulmonary artery pressure and capillary wedge pressure did not change significantly. This study suggests that concomitant mild to moderate left ventricular failure is not a contra-indication to nicardipine therapy in patients with angina.

Adult↗
PubMed1985

Cardiac hypertrophy, hypertrophic cardiomyopathy, and hyperparathyroidism--an association.

Left ventricular hypertrophy (symmetric, asymmetric, or hypertrophic cardiomyopathy) is an almost invariable accompaniment of primary hyperparathyroidism. Five of 18 patients with hypertrophic cardiomyopathy had raised serum concentrations of parathyroid hormone with normal serum calcium concentrations. Left ventricular hypertrophy did not occur in any of the six patients with hypercalcaemia alone. These relations suggest that parathyroid hormone rather than a rise in the extracellular calcium concentration is associated with a spectrum of left ventricular hypertrophy. All patients with increased circulating parathyroid hormone concentrations should have echocardiographic examination of the left ventricle. Conversely, parathyroid hormone concentrations should be measured in all patients with left ventricular hypertrophy from an unknown cause, especially those with hypertrophic cardiomyopathy.

Adult↗
PubMed1984

Investigation of left ventricular function by digital subtraction angiography.

Twenty five patients who had undergone conventional coronary arteriography and left ventriculography for suspected coronary artery disease had left ventriculography performed by digital subtraction angiography as outpatients; there were no complications requiring admission to hospital. A catheter was introduced percutaneously and positioned in the superior vena cava; 40-50 ml of contrast medium was injected at 16-18 ml/s. Left ventriculograms were recorded in the 30 degrees right anterior oblique projection. Diagnostic images were recorded in each case. Left ventricular wall movement was assessed as normal in nine patients, globally hypokinetic in 10, and aneurysmal in six. In each case there was agreement between the two methods. Ejection fraction varied between 17% and 78%. It is concluded that digital subtraction angiography provides a reliable assessment of overall left ventricular function and distinguishes between those patients with a potentially resectable lesion and those with global impairment of function.

Adult↗
PubMed1981

Regional non-uniformity of left ventricular wall movement in man.

In order to assess the possible importance of regional non-uniformity of left ventricular function, angiograms of 42 normal subjects and 105 patients with coronary artery disease were digitised frame by frame. Regional curvature around the cavity was assessed, only positive curvature being compatible with ellipsoidal geometry. In normal subjects, positive curvature of the anterior wall was shown by all, but on the inferior wall was present in only 12 (28%) at end-diastole and five (12%) at end-systole. In patients with ischaemic heart disease, anterior wall curvature was again positive in all but four with apical aneurysm, but positive curvature of the inferior wall was present more frequently than normal, 47 (42%) at end-diastole and 39 (36%) at end-systole. In these patients, positive curvature at end-diastole was associated with reduced wall movement during ejection. Though the pattern of coronary artery involvement was random, there were conspicuous regional differences in the distribution of abnormal wall movement during isovolumic relaxation. Outward movement was found only on the anterior wall. Abnormal inward movement was five times as frequent on the inferior wall as on the anterior. An ellipsoidal cavity outline is not therefore characteristic of the normal left ventricle and, when present, this configuration is likely to be associated with a reduced amplitude of inferior wall movement. Regional differences of both structure and function can thus be shown in normal and abnormal hearts. They may arise from variation in local fibre architecture. Their presence must be taken into account in interpreting abnormalities of left ventricular function.

Coronary Angiography↗
PubMed1981

Left ventricular fibre architecture in man.

In order to investigate the possibility of regional variation of ventricular structure, 25 normal postmortem human hearts were studied by inspection of cavity shape and subepicardial fibre orientation, by dissection, and by the histology of sections in two orthogonal planes. Ventricular architecture was complex. Inlet and outlet long axes were separated by 30 degrees in the left ventricle. In the right the corresponding figure was 90 degrees. The thickest part of the left ventricular wall was at the base. At the apex there was potential endo- and epicardial continuity. Left ventricular cavity shape departed significantly from any simple geometric figure, there being, consistently, regions of both positive and negative curvature on the diaphragmatic aspect. The presence of trabeculae caused considerable variation in wall thickness. Striking variation was found in the arrangement of subepicardial muscle fibres. Most pronounced was the contrast between the longitudinal arrangement of fibres observed on the oblique margin and the circumferential arrangement of those on the acute. On the diaphragmatic surface of the left ventricle, fibres near the crux and apex ran circumferentially while those between ran obliquely; those on the diaphragmatic surface of the right ventricle also ran circumferentially. Deeper in the myocardium the arrangement was simpler. In the mid-wall of the left ventricle fibres were circumferential, best developed towards the base and in the upper part of the septum. Near the apex of the left ventricle and in the mid-wall of the right ventricle such fibres were sparse. The subendocardial region consisted of longitudinally directed fibres forming the trabeculae and papillary muscles, while fibres deep to and between the trabeculae coursed more obliquely. These findings were confirmed by histology. Models based on uniform myocardial fibre structure cannot explain wall movement in normal subjects, and are likely to have significant limitations if used to investigated left ventricular function in disease.

Dissection↗