Biomedical subjects
Publications and source records attributed to M R Cowie.
Statin therapy reduces the risk of cardiac events by 30% in both primary and secondary prevention. Although fine-tuning of the evidence will occur as more clinical trials report, the challenge is now to implement the evidence to the benefit of patients.
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The burden that heart failure imposes on the health care systems of the developed world is substantial and increasing. This article reviews the world literature on the epidemiology of heart failure and discusses the key methodological issues for research in this field.
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AIMS: To determine the incidence and aetiology of heart failure in the general population. METHODS AND RESULTS: New cases of heart failure were identified from a population of 151 000 served by 82 general practitioners in Hillingdon, West London through surveillance of acute hospital admissions and through a rapid access clinic to which general practitioners referred all new cases of suspected heart failure. On the basis of clinical assessment, electrocardiography, chest radiography and transthoracic echocardiography, a panel of three cardiologists decided that 220 patients met the case definition of new heart failure over a 20 month period (crude incidence rate of 1.3 cases per 1000 population per year for those aged 25 years or over). The incidence rate increased from 0.02 cases per 1000 population per year in those aged 25-34 years to 11.6 in those aged 85 years and over. The incidence was higher in males than females (age-adjusted incidence ratio 1.75 [95% confidence interval 1.34-2.29, P<0.0001]). The median age at presentation was 76 years. The primary aetiologies were coronary heart disease (36%), unknown (34%), hypertension (14%), valve disease (7%), atrial fibrillation alone (5%), and other (5%). CONCLUSIONS: Within the general population, new cases of heart failure largely occur in the elderly, and the incidence is higher in men than women. The single most common aetiology is coronary heart disease, but in a third of cases the aetiology cannot be determined on the basis of non-invasive investigation alone. To be relevant to clinical practice, future clinical trials in heart failure should not exclude the elderly.
BACKGROUND: The reliability of a clinical diagnosis of heart failure in primary care is poor. Concentrations of natriuretic peptides are high in heart failure. This population-based study examined the predictive value of natriuretic peptides in patients with a new primary-care diagnosis of heart failure. METHODS: Concentrations of plasma atrial (ANP and N-terminal ANP) and B-type (BNP) natriuretic peptides were measured by radioimmunoassay in 122 consecutive patients referred to a rapid-access heart-failure clinic with a new primary-care diagnosis of heart failure. On the basis of clinical assessment, chest radiography, and transthoracic echocardiography, a panel of three cardiologists decided that 35 (29%) patients met the case definition for new heart failure. ANP and NT-ANP results were available for 117 patients (34 with heart failure) and BNP results for 106 (29 with heart failure). FINDINGS: Geometric mean concentrations of natriuretic peptides were much higher in patients with heart failure than in those with other diagnoses (29.2 vs 12.4 pmol/L for ANP; 63.9 vs 13.9 pmol/L for BNP; 1187 vs 410.6 pmol/L for NT-ANP; all p < 0.001). At cut-off values chosen to give negative predictive values for heart failure of 98% (ANP > or = 18.1 pmol/L, NT-ANP > or = 537.6 pmol/L, BNP > or = 22.2 pmol/L), the sensitivity, specificity, and positive predictive value for ANP were 97%, 72%, and 55%; for NT-ANP 97%, 66%, and 54%; and for BNP 97%, 84%, and 70%. Addition of ANP or NT-ANP concentration or both did not improve the predictive power of a logistic regression model containing BNP concentration alone. INTERPRETATION: In patients with symptoms suspected by a general practitioner to be due to heart failure, plasma BNP concentration seems to be a useful indicator of which patients are likely to have heart failure and require further clinical assessment.
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Familial polyarteritis nodosa (PAN) is rare. We describe here two siblings who developed PAN 8 years apart. HLA typing showed that the affected family members shared a common haplotype with their unaffected mothers. Further study of the family history suggested the possibility of an inherited disorder of connective tissue predisposing to autoimmunity and aneurysm formation.
Anomalous origin of the left coronary artery from the pulmonary artery (the Bland-White-Garland syndrome) is a rare congenital cardiac defect which may present for the first time in adulthood. The recognition of this disorder, which produces widespread left ventricular ischaemia and the risk of sudden death, myocardial infarction and congestive heart failure, is important as the prognosis can be improved by surgical intervention. Thallium-201 scintigraphy has a useful role in demonstrating the widespread nature of the ischaemia of the left ventricle, whilst the diagnosis is confirmed at cardiac catheterisation.
Vertebral osteomyelitis due to Staphylococcus epidermidis is extremely rare and usually occurs in the context of immunosuppression in association with an adequate portal of entry for infection. This paper reports a case of vertebral osteomyelitis due to S. epidermidis in a man with no evidence of immunosuppression or obvious portal of entry. The patient presented with severe back pain but there were no clinical signs of infection. Radiographs and computerized tomographs showed destruction of thoracic vertebral bodies and an adjacent soft tissue mass. S. epidermidis was grown from multiple blood cultures. All isolates had identical antibiograms and biochemical profiles. There was evidence of healing of the vertebral bodies and resolution of the soft tissue mass after appropriate antistaphylococcal treatment.
OBJECTIVES: Out-of-hospital sudden cardiac arrest is a key area in which to study the dual problem of the poorer health status of minority populations and their poorer access to the health care system. We proposed to examine the relationship between race (Black/White) and survival. METHODS: We determined the incidence and outcome of cardiac arrests in Seattle for which medical assistance was requested. RESULTS: Over a 26-month period, the age-adjusted incidence of out-of-hospital cardiac arrest was twice as great in Blacks than in Whites (3.4 vs 1.6 per 1000 aged 20 and over). The initial resuscitation rate was markedly poorer in the Black victims (17.1% vs 40.7%), and rates of survival to hospital discharge were also lower in Blacks (9.4% vs 17.1%). Both effective initial resuscitation and survival were significantly related to White race following adjustment for other covariates. CONCLUSION: The differences in outcomes were not fully explained by features of the collapse or relevant service factors. Possible explanations include delays in instituting therapy, less bystander-initiated cardiopulmonary resuscitation, poorer levels of health, and differences in the underlying cardiac disorders.
1. In six healthy subjects the amplitude and phase of respiratory sinus arrhythmia were determined at five different respiratory cycle lengths ranging from 3 to 9.5 s. 2. At each respiratory cycle length the carotid baroreceptor-heart rate reflex response was determined by cyclical neck suction at -40 mmHg at five different cycle lengths covering the same range of 3-9.5 s. 3. The application of cyclical neck suction increased the amplitude of respiratory sinus arrhythmia in all but the longest respiratory cycle lengths. 4. With increasing respiratory cycle length the amplitude of sinus arrhythmia increased, and R-R intervals were at their longest at an earlier phase of the respiratory cycle. Similarly, with increasing suction cycle length the amplitude of the cardiac interval response increased and the phase angle decreased. 5. The cardiac interval responses to respiration and to neck suction at different frequencies were independent of each other, the heart rate at any moment resulting from the algebraic summation of the two responses.
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1. Carotid baroreceptor-heart rate sensitivity has been measured non-invasively by a modified neck-chamber method that utilizes all cardiac intervals recorded in 6 min during 84 respiratory cycles. 2. In a replication study in 10 subjects the mean baroreflex sensitivity was 5.52 ms/mmHg and the mean (SD) difference between determinations was 0.70 (0.74) ms/mmHg. 3. Baroreflex sensitivity was measured in 48 untreated subjects of mean age 43 (range 20-71) years with blood pressures ranging from 104 to 202 mmHg (13.9 to 26.9 kPa) systolic and 52 to 120 mmHg (6.9 to 16.0 kPa) diastolic [average 142/87 mmHg (18.9/11.6 kPa)]. Both systolic and diastolic pressures correlated with age (r = 0.53, P less than 0.001 and r = 0.44, P less than 0.01). 4. Baroreflex sensitivity determined throughout respiration was log-normally distributed with a median value of 2.24 ms/mmHg, which declined with age (r = -0.63, P less than 0.001). 5. After allowing for the effects of age, baroreflex sensitivity throughout respiration was not independently related to either systolic or diastolic blood pressure.
Sensitive biological assays of toxin/antitoxin potency have been developed to assist in research on characterization of salivary toxins of the Australian paralysis tick Ixodes holocyclus and on immunity to tick paralysis. The toxin assay utilizes suckling mice (4-5 g); a quantitative paralysis index is applied over a range of doses. The antitoxin assay is based on an in vitro/in vivo neutralization test which required a sensitive toxin assay and methods of standardization of toxin preparations. This assay permits the monitoring of blood antibody levels in animals during the course of development and loss of immunity and is assisting a study into the feasibility of producing an anti-paralysis vaccine. The method also allows standardization of commercial tick paralysis antiserum. The methods and applications are described and comparisons made with previous assays. Sample data are examined statistically by regression and variance analyses; parallelism of dosage-response lines is tested and relative toxicities (toxin) or potencies (antiserum) calculated.
Cardiovascular diseases are increasingly recognised as an important cause of morbidity and mortality in developing countries. This is due to the ageing of the population and better control of communicable disease and malnutrition. We review the published data on the epidemiology of heart failure in such countries. Rheumatic heart disease remains a major cause of heart failure in Africa and Asia, especially in the young. Hypertension is an important cause of heart failure especially in the African and African-American population. Chagas' disease is still a cause of heart failure in South America. However, as countries go through epidemiological transition and undergo socio-economic development, the epidemiology of heart failure becomes increasingly similar to that of Western Europe and North America with coronary artery disease being the single most common cause of heart failure. Preventive and public health strategies need to be specific to the local epidemiological characteristics.
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