Exercise-induced cardiac hypertrophy: a substrate for sudden death in athletes?

Cardiac hypertrophy is a general term signifying an increase in cardiac mass in response to applied stress. In mild, early hypertrophy, cardiac myocyte contractile performance may be normal or enhanced, whereas in severe hypertrophy associated with cardiac failure, myocyte contraction is reduced in amplitude and increased in duration. In contrast to the varied contractile response, the duration of electrical excitation shows similar changes in both mild and severe hypertrophy. Action potential duration in mid-myocardial and sub-epicardial layers is increased, which is associated with ventricular arrhythmias (in a similar manner to the long QT syndromes from other causes), based on afterdepolarizations and enhanced automaticity. Single-cell studies following exercise training in animal models show that exercise-induced cardiac hypertrophy displays features similar to mild, compensated hypertrophy from other causes. Developed shortening of unloaded single cells is increased or unchanged, and developed force in single myocytes is enhanced. Action potential duration is increased, apart from in the sub-endocardial layer. As with mild hypertrophy from other causes, this will be pro-arrhythmic because of altered dispersion of repolarization and enhanced automaticity. Major abnormalities of the ECG in man include frequent and complex ventricular ectopy, ST segment changes and prolongation of repolarization. In this review a case is presented for regarding exercise-induced cardiac hypertrophy as being no different from mild cardiac hypertrophy resulting from other, pathological causes. The cellular electrophysiological changes are sufficient to account for many of the abnormalities of the ECG, including high-grade ventricular ectopy. Sudden death in trained athletes who have no evidence of specific heart disease may be a direct consequence of cardiac hypertrophy and altered repolarization.

A topographical study of mechanical and electrical properties of single myocytes isolated from normal guinea-pig ventricular muscle

Major regional differences in the electrical properties of myocytes from ventricular muscle have been described previously, on the basis of samples taken from a maximum of three regions in each heart. In order to define the topographical basis for such differences, we studied the electrical and mechanical properties of single myocytes isolated from 20 regions throughout the ventricles in the normal guinea-pig heart. Single myocytes were isolated using an enzymatic dispersion method, and were studied under conditions that were close to physiological. Cell capacitance and action potentials were recorded using the switch-clamp technique, and cell length and evoked shortening were measured using a photodiode array system. In the left ventricular free wall, mid-myocardial cells were longer and had greater capacitative surface area than surface myocytes. There were transmural but not longitudinal differences in APD90 (action potential duration to 90% repolarization), with the longest APD90 in subendocardial and the shortest in subepicardial myocytes. We found a septum-left ventricular free wall-right ventricular free wall gradient, with the longest APD90 in the septum and the shortest in the right ventricular free wall. The regional distribution of APD90 was closely mirrored by relaxation time. Peak cell shortening was greater in subendocardial myocytes than in subepicardial myocytes in the left ventricular free wall, and in myocytes from the left side of the septum compared with the right. We concluded that the regional distribution of APD is closely and inversely related to the sequence of ventricular depolarization, and that the regional variations in cell shortening amplitude are related principally to reported regional variations in wall stress.

"That sort of place...where filthy men go...": a qualitative study of women's perceptions of genitourinary medicine services

BACKGROUND

A stigma is a pejorative social label. Stigmatisation is a process by which individuals are made to experience isolation and reduced opportunities in life. Some diseases are particularly associated with stigmatising attitudes; this applies particularly to sexually transmitted infections. Although several studies report the effects of stigma, no study to date has attempted to investigate its nature, which is a prerequisite to designing health interventions.

METHODS

This qualitative, exploratory study investigated the experience of stigma among young women recently diagnosed with an STI and considered the implications of these experiences in terms of maximising access to GUM clinics.

RESULTS

Three themes were identified from interviews undertaken with women recruited in family planning and genitourinary medicine (GUM) clinics: the perception of STIs as a condition of "others," the threatening nature of the GUM clinic, and the evolution of the experience of stigma within the GUM clinic.

CONCLUSION

More open discussion and education about sexual health services and STIs should take place at a general population level; awareness of sexual health services should be raised in inclusive ways, which are seen as relevant to the needs of a wide range of individuals; medical, nursing, and counselling staff in GUM clinics should be supported in their efforts to reduce the experience of stigma. Finally, future interventions designed to improve access to sexual health services should formally assess their impact on stigma.

Mechanisms underlying delayed afterdepolarizations in hypertrophied left ventricular myocytes of rats

Cardiac hypertrophy was induced in rats by daily injection of isoproterenol (5 mg/kg ip) for 7 days. Membrane voltage and currents were recorded using the whole cell patch-clamp technique in left ventricular myocytes from control and hypertrophied hearts. Ryanodine-sensitive delayed afterdepolarizations (DADs) and transient inward current (I(ti)) appeared in hypertrophied cells more often and were of larger amplitude than in control cells. DADs and I(ti) are carried principally by Na/Ca exchange with smaller contributions from a nonselective cation channel and from a Cl- channel. The latter is expressed only in hypertrophied myocytes. In hypertrophy, the density of caffeine-induced Na/Ca exchange current (I(Na/Ca)) was increased by 26%, sarcoplasmic reticulum (SR) Ca2+ content as assessed from the integral of I(Na/Ca) was increased by 30%, the density of Na-pump current (I(pump)) was reduced by 40%, and the intracellular Na+ content, measured by Na+-selective microelectrodes was increased by 55%. The results indicate that DADs and I(ti) are generated by spontaneous Ca2+ release from an overloaded SR caused by a downregulated Na pump and an upregulated Na/Ca exchange. These findings may explain the propensity for arrhythmias seen in this model of hypertrophy.

Rate-dependent electrical, contractile and restitution properties of isolated left ventricular myocytes in guinea-pig hypertrophy

Left ventricular hypertrophy predisposes to sudden cardiac death (SCD) and studies of human SCD suggest that the antecedent heart rate (HR) is usually < 100 beats min(-1). This is surprising in view of the known association between adrenergic receptor stimulation and SCD which by itself would suggest that it is more likely to occur from high rather than low HR. We therefore hypothesized that there may be electrical or mechanical abnormalities present in myocytes isolated from animals with left ventricular hypertrophy that predispose to SCD at low stimulation frequencies but which may not be present at high HR. Mild left ventricular hypertrophy was induced in guinea-pigs by infra-renal aortic banding. Electrical and mechanical properties of isolated myocytes were studied at different stimulation frequencies between 0.1 and 3 Hz. Action potential duration (APD) is prolonged in hypertrophy at stimulation frequencies < 1 Hz but not at faster rates. Contraction size, time-to-peak contraction (TTPC) and half-relaxation time are greatly enhanced in hypertrophy at all frequencies between 0.1 and 3 Hz. Electrical (50.3 +/- 5.2 ms in hypertrophy and 78.4 +/- 12.1 ms in control, P < 0.03) and mechanical (205 +/- 16 ms for hypertrophy and 266 +/- 24 ms for control cells, P < 0.03) restitution time constants are quicker in hypertrophy. The finding of APD prolongation at low but not at high frequencies is consistent with the finding that SCD arises from low and not high HR. This data supports the role of abnormal repolarization in SCD.

The use of a modified technique to reduce radioactive air contamination in aerosol lung ventilation imaging

The aim of this study was to reduce airborne contamination resulting from the use of aerosols in lung ventilation scintigraphy. Lung ventilation imaging is frequently performed with 99mTc-diethylenetriaminepentaacetate aerosol (DTPA), derived from a commercial nebuliser. Airborne contamination is a significant problem with this procedure; it results in exposure of staff to radiation and can reduce gamma camera performance when the ventilation is performed in the camera room. We examined the level of airborne contamination resulting from the standard technique with one of the most popular nebuliser kits and tested a modification which significantly reduced airborne contamination. Air contamination was measured while ventilating 122 patients. The modified technique reduced air contamination by a mean value of 64% (p = 0.028) compared with the standard control technique. Additionally, differences in contamination were examined when a mask or mouthpiece was used as well as differences between operators. A simplified method of monitoring air contamination is presented using a commonly available surface contamination monitor. The index so derived was proportional to air contamination (r = 0.88). The problems and regulations associated with airborne contamination are discussed.

An extracorporeal membrane oxygenation-based approach to cardiogenic shock in an older population

BACKGROUND

We investigated the efficacy of an integrated system of advanced supportive care based on extracorporeal membrane oxygenation (ECMO) in older patients with an estimated mortality of more than 90% to establish whether its use is justifiable.

METHODS

Treatment was provided by cardiac surgeons and critical care physicians and included the following key elements: (1) ECMO, (2) early application of continuous venovenous hemofiltration, (3) inhaled nitric oxide, (4) maintenance of perfusion pressure with norepinephrine, (5) maintenance of pulmonary blood flow by ventricular filling with intravenous colloids, (6) avoidance of early postoperative anticoagulation, (7) frequent use of transesophageal echocardiography, and (8) low tidal volume ventilation. Demographic features, intraoperative details, postoperative course, ECMO weaning rate, morbidity, survival to hospital discharge, and the quality of life of survivors were recorded.

RESULTS

Seventeen consecutive patients (median age, 69 years) with refractory cardiogenic shock were studied. The median duration of ECMO was 86 hours (20 to 201 hours). Eleven patients (65%) were successfully weaned from ECMO. Seven patients (41%) survived to discharge. The major causes of morbidity were bleeding and leg ischemia. All patients who survived to discharge were alive and well at follow-up (median, 21 months) and reported a satisfactory quality of life.

CONCLUSIONS

An ECMO-based approach can be used with acceptable results in the treatment of refractory cardiogenic shock, even in older patients.

Telephone support group intervention for persons with hemophilia and HIV/AIDS and family caregivers

The purpose of this pilot project was to test the feasibility of a telephone support group intervention for persons with hemophilia and HIV/AIDS and for their family caregivers. Their support needs were unique because they did not identify with predominant groups of persons with AIDS and were geographically dispersed from peers. The 12 week intervention involved separate telephone support groups for hemophiliacs and for family caregivers. The two groups, comprised of a predetermined maximum of six people, were co-led by a professional and a peer. The support group for family caregivers involved six people and the group for men with hemophilia included five people, including one peer facilitator and one professional facilitator in each group. The telephone support group discussions were taped, transcribed, and analyzed for prevalent themes. The peer and professional facilitators maintained weekly field notes. All participants reported that the telephone groups had a positive impact on meeting their support needs. They believed that they had benefitted from sharing information and that the support groups had decreased their feelings of isolation and loneliness. Participants, however, contended that the intervention should be longer than 12 weeks.

Histological and immunological parameters to predict treatment outcome of Helicobacter pylori eradication in low-grade gastric MALT lymphoma

Helicobacter pylori eradication is generally accepted as the first choice of treatment for stage IE low-grade gastric MALT lymphoma (mucosa-associated lymphoid tissue-type lymphoma). Treatment failure may be attributed to the extent of the disease and to progression into an antigen-independent phase. This study assessed the value of morphological grading and the expression of the co-stimulatory markers CD40, CD80 and CD86 and their ligands to predict clinical outcome in 23 consecutive low-grade MALT lymphoma patients treated with H. pylori eradication. Complete regression was achieved in 13/23 patients (56%), partial regression in two (9%), and no response in eight (35%). Histological grading was highly predictive of clinical response, especially in stage IE(1) patients, with complete remissions in 10/12 tumours with purely low-grade (type A) morphology and 1/8 tumours with increased numbers of blasts (type B) (p=0.0046) and was related to the expression of costimulatory markers (p=0.0061). Moreover, CD86 as a single marker proved to be of predictive value for treatment outcome (p=0.0086). These results suggest that morphological grading and immunological criteria can be defined to recognize the transition into the antigen-independent phase of gastric MALT-NHL. In addition to clinical stage, these critera may in future serve as a practical pathological guide to the choice of therapy.

Early and intensive continuous hemofiltration for severe renal failure after cardiac surgery

BACKGROUND

The aim of this study was to test whether early and intensive use of continuous venovenous hemofiltration (CVVH) achieved a better than predicted outcome in patients with severe acute renal failure undergoing cardiac operations, and whether a simple and yet accurate model could be developed to predict their outcome before starting CVVH.

METHODS

Medical record analysis with collection of demographic, clinical, and outcome information was used.

RESULTS

Sixty-five consecutive patients were treated with early and intensive CVVH (mean operation to CVVH time, 2.38 days; pump-controlled ultrafiltration rate, 2 L/h) after coronary artery bypass grafting (56.9%), single valve procedure (16.9%), or combined operations (26.2%). In 32.3% of patients, intraaortic balloon counterpulsation was required and 20% of patients were emergencies. Sustained hypotension despite inotropic and vasopressor support occurred in 40% of patients and prolonged mechanical ventilation in 58.5%. Using an outcome prediction score specific for acute renal failure, the predicted risk of death was 66%. Actual mortality was 40% (p = 0.003). Using multivariate logistic regression analysis and neural network analysis, patient outcome could be predicted with good levels of accuracy (receiver operating characteristic 0.89 and 0.9, respectively).

CONCLUSIONS

Early and aggressive CVVH is associated with better than predicted survival in severe acute renal failure after cardiac operations. Using readily available clinical data, the outcome of such patients can be predicted before the implementation of CVVH.

Histological and immunological parameters to predict treatment outcome of Helicobacter pylori eradication in low-grade gastric MALT lymphoma

Helicobacter pylori eradication is generally accepted as the first choice of treatment for stage IE low-grade gastric MALT lymphoma (mucosa-associated lymphoid tissue-type lymphoma). Treatment failure may be attributed to the extent of the disease and to progression into an antigen-independent phase. This study assessed the value of morphological grading and the expression of the co-stimulatory markers CD40, CD80 and CD86 and their ligands to predict clinical outcome in 23 consecutive low-grade MALT lymphoma patients treated with H. pylori eradication. Complete regression was achieved in 13/23 patients (56%), partial regression in two (9%), and no response in eight (35%). Histological grading was highly predictive of clinical response, especially in stage IE(1) patients, with complete remissions in 10/12 tumours with purely low-grade (type A) morphology and 1/8 tumours with increased numbers of blasts (type B) (p=0.0046) and was related to the expression of costimulatory markers (p=0.0061). Moreover, CD86 as a single marker proved to be of predictive value for treatment outcome (p=0.0086). These results suggest that morphological grading and immunological criteria can be defined to recognize the transition into the antigen-independent phase of gastric MALT-NHL. In addition to clinical stage, these critera may in future serve as a practical pathological guide to the choice of therapy.

Heterosexism and homophobia in Scottish school sex education: exploring the nature of the problem

This paper focuses on instances of heterosexism and homophobia, as well as examples of good practice in sex education, observed in 25 Scottish schools. Possible reasons for why good practice is not more widespread are explored. Qualitative and quantitative data are presented. Various constraints to good practice are identified by teachers, and are discussed in the context of survey data on pupil attitudes towards same-sex sexual relationships, and on teacher confidence in teaching about homosexuality.

Qualitative analysis of psychosocial impact of diagnosis of Chlamydia trachomatis: implications for screening

OBJECTIVES

To investigate the psychosocial impact for women of a diagnosis of Chlamydia trachomatis and discuss the implications for the proposed UK chlamydia screening programme.

DESIGN

Qualitative study with semistructured interviews. Interview transcripts analysed to identify recurrent themes.

PARTICIPANTS

Seventeen women with a current or recent diagnosis of chlamydia.

SETTING

A family planning clinic and a genitourinary medicine clinic in Glasgow.

RESULTS

Three themes were identified: perceptions of stigma associated with sexually transmitted infection, uncertainty about reproductive health after diagnosis, and anxieties regarding partner's reaction to diagnosis. Most women had not previously perceived sexually transmitted infections as personally relevant; this was a function of stereotypical beliefs about who was "at risk" of sexually transmitted infection. These beliefs were pervasive and negatively affected reactions to diagnosis and produced anxiety about disclosure of the condition to others (particularly sexual partners) and future reproductive morbidity. This anxiety, given the uncertain natural history of chlamydia, may prove difficult to dispel.

CONCLUSIONS

There are three primary areas of concern for women after a diagnosis of chlamydia which need to be examined in the proposed screening programme. Information provided should normalise and destigmatise chlamydial infection and positively promote genitourinary medicine services. Support services should be available because notification of partner can cause anxiety. Uncertainty about future reproductive morbidity may be inevitable; staff providing screening will require guidance in providing advice under such conditions.

Can clinical assessment of chest pain be made more therapeutic?

We describe the referral and management of consecutive patients attending a cardiac service with the presenting complaint of chest pain. Of 610 consecutive new referrals to five Oxford cardiac clinics over 12 weeks, 202 had chest pain as the presenting complaint: 91 (45%) angina, 101 (50%) non-cardiac chest pain, 8 (4%) both and 2 (1%) uncertain diagnosis. Information in clinic letters was sometimes ambiguous and contradictory and suggested a lack of precise information to patients. Patients with non-cardiac chest pain often had long histories, including considerable previous use of services and specialist investigations. There were delays in referral and assessment of patients. There are opportunities for simple changes in assessment procedures which might have substantial advantages for outcome and resource: (i) more detailed referral information from general practitioners, with an explicit statement of the reasons for referral; (ii) minor modifications to augment the assessment by provision of unambiguous information to patients and primary care at discharge.

The effects of [K+]o on regional differences in electrical characteristics of ventricular myocytes in guinea-pig

Altering [K+]o might have different effects on action potential duration (APD) in myocytes from different regions. Therefore, the effects of [K+]o on regional differences in action potential characteristics were investigated in sub-endocardial, mid-myocardial and sub-epicardial myocytes isolated from the base of guinea-pig left ventricular free wall using three different [K+]o (2.7, 5.4 and 8.1 mM KCl). Action potentials were recorded using the switch-clamp technique at 0.5 Hz. Increasing [K+]o from 2.7 to 8.1 mM shortened the action potential duration to 90 % repolarization (APD90; mean APD90 values in sub-endocardial, mid-myocardial and sub-epicardial myocytes were, respectively, 295 +/- 9, 286 +/- 9 and 266 +/- 8 ms in 2.7 mM [K+]o, 270 +/- 7, 255 +/- 7 and 215 +/- 7 ms in 5.4 mM [K+]o, 234 + 7, 212 +/- 10 and 155 +/- 8 ms in 8.1 mM [K+]o), depolarized the resting potential, and reduced the amplitude of the action potential. The effect of increasing [K+]o on action potential characteristics was more pronounced in sub-epicardial myocytes than in sub-endocardial and mid-myocardial myocytes. The regional differences in APD90 in 5.4 mM [K+]o were increased in 8.1 mM [K+]o and abolished in 2.7 mM [K+]o. In conclusion, changing [K+]o produces more pronounced effects on action potentials in sub-epicardial myocytes than in sub-endocardial myocytes, modifying the normal heterogeneity of action potentials. The differences in the response of sub-epicardium and sub-endocardium to [K+]o may contribute to the flattening or inversion of the T wave commonly seen in patients presenting with hypokalaemia and the upright and tall T waves observed in electrocardiograms recorded during hyperkalaemia, although the underlying ionic currents remain to be determined.

Men's sexual health matters: promoting reproductive health in an international context

Recent concern regarding the control of sexually transmitted infections (STIs) has resulted in an increased interest in the sexual health of men. This interest has primarily focused on strategies to 'encourage and enable men to take responsibility for their sexual and reproductive behaviour and their social and family roles' (United Nations 1994). Whilst men are deemed to have 'responsibilities', women are said to have 'rights' with regard to making choices about reproductive health and accessing appropriate and effective services. Here it is argued that, whilst provision of services and interventions against STIs in men should never be at the expense of those for women, it is often clinically easier and more effective to diagnose and treat men with STIs compared to women in resource-poor settings. Indeed, this may prove to be an effective strategy in controlling the spread of STIs, and hence reducing the disproportionate burden of their complications suffered by women. The paper reviews key issues in relation to improved service delivery for sexual and reproductive health in men, notably: the heterogeneity of male populations; current knowledge regarding men's sexual behaviour; the role of sexuality; methods of studying sexual behaviour in resource poor countries; men's own concerns in relation to sexual and reproductive health; and where and how they access treatment. It is argued that the time has now come to determine and address men's sexual health needs if we are to expect them to participate fully as responsible partners in improving and protecting their own and others' sexual and reproductive health.

Attitudes, beliefs and behaviour regarding the use of sunbeds amongst healthcare workers in Bradford

Although cosmetic tanning and unprotected solar exposure are common, little is known about general attitudes, beliefs and behaviour regarding the use of sunbeds. We sought to determine the frequency of sunbeds use in a select sample and to assess the knowledge and beliefs regarding this behaviour. A self-administered anonymous questionnaire was distributed to a sample of 648 employees work for Bradford Hospitals NHS Trust. The questionnaire explored demographic information (including hair and skin type, family history with skin cancer), frequency of sunbeds use, knowledge about the risks of UV exposure and motivations for practising this behaviour. Four hundred and eighteen women and 52 men completed the questionnaire, making a response rate of 73%. Nearly half of respondents (207; 44%) reported using sunbeds to some extent; of those 12% reported frequent use. Appearance ('to look better') was the most popular reason given by respondents for using sunbeds, followed by 'feel healthy'. Frequency of using sunbeds was found to be negatively correlated with the age of respondents and the existence of family experience with skin cancer, and strongly associated with the opinion that it is safer to use a sunbed than subathing outdoors, the female sex and smoking. It is clear from this study that the psychological factors that influence sunbeds use are complex and that so far public education campaigns have had little impact on it. This study highlights some of these psychological factors.