Clinical articles

Low-dose aspirin is of value in the long-term management of vascular disease, and the giving of aspirin to patients believed to be experiencing an acute myocardial infarction (AMI) is standard practice for paramedics and doctors in most countries. Given during infarction, aspirin may disaggregate platelet microthrombi and may reduce the size of a developing thrombus. Effects of aspirin other than on platelets have also been suggested and these include an increase in the permeability of a fibrin clot and an enhancement of clot lysis. Animal experiments have also shown a direct effect of aspirin upon the myocardium with a reduction in the incidence of ventricular fibrillation.

Randomised trials have shown that the earlier aspirin is taken by patients with myocardial infarction, the greater the reduction in deaths. We suggest, therefore, that patients known to be at risk of an AMI, including older people, should be advised to carry a few tablets of soluble aspirin at all times, and chew and swallow a tablet immediately, if they experience severe chest pain. 

Intra-coronary imaging has become a cornerstone of visualising atherosclerotic coronary artery disease and also to guide the therapy in selected high-risk cases. Optical coherence tomography (OCT) is an imaging modality quite similar to intravascular ultrasound (IVUS), but uses light instead of sound. In the second article on contemporary coronary imaging, the potential of OCT is discussed.

Infective endocarditis (IE) causes high rates of morbidity and mortality. Clinical management is problematic if there are uncertainties over the identity, viability or antibiotic susceptibility of the causative organism. Between 10% and 30% of IE blood cultures are negative, usually a result of prior antimicrobial therapy, but also occurring when causative micro-organisms are non-cultivable or fastidious. While evidence-based guidelines exist for treatment of IE caused by defined agents, clinicians are often faced with the dilemma of IE of unproven aetiology. Duration of empirical therapy is usually titrated against overall clinical response and non-specific laboratory markers of inflammation, but these may bear little relation to ongoing microbial activity in the heart valve. There is an increasing need for more specific, sensitive and rapid tests for the identification of causative organisms. Nucleic acid amplification technologies (NAATs) show promise for rapid detection of pathogen nucleic acid in blood or tissue. This review discusses the developments in this field, and the potential for the application of NAATs to improve aetiological identification in IE.

There is much debate about the optimal sedation strategy for transoesophageal echocardiography (TEE). Despite previous studies demonstrating the potential benefits of combining opiates and benzodiazepines for conscious sedation, and previous published national surveys and recommendations, sedation practice for TEE in clinical practice varies widely within the UK. All UK centres routinely use midazolam, but only 7% of centres use it in combination with an opiate: 14% of hospitals report no routine use of sedation for TEE. There
is no British Society of Echocardiography (BSE) recommended TEE sedation protocol within the UK and even where guidelines exist locally, 82% of operators report being unaware of their details. Consequently, a wide range of sedative doses are used and many patients are reported to be over-sedated. We developed a new protocol for conscious sedation using intravenous pethidine and midazolam for TEE and have shown it to be safe and effective when implemented within an existing TEE service.

From the days of Virchow and the analysis of post-mortem coronary specimens, an enormous amount of knowledge has been built about coronary pathophysiology. In the 1950s the dream of in vivo coronary imaging became a reality with the invention of coronary arteriography under the guidance of Mason Sones. As we fast forward 50 years, it has become clear that angiography has helped us focus on areas of stenosis and flow limitation, but the main problem of coronary artery disease is much more complex than can appear on a luminal silhouette. The finding of ‘normal coronary arteries’ following angiography is short-sighted and does not take into account the potential of unstable disease lurking within the vessel wall. We begin the series with intravascular ultrasound.

In UK cardiac rehabilitation programmes, exercise training is often set at a percentage of maximal heart rate or heart rate reserve, either predicted or measured. Problems may arise when using this method for chronic heart failure (CHF) patients who often have chronotropic incompetence and are treated with beta blockers. A safer approach is to use cardiopulmonary exercise testing to prescribe training below the ventilatory threshold, thus ensuring that the exercise is moderate. The aim of this study was to determine whether British Association for Cardiac Rehabilitation (BACR) heart rate guidelines prescribe moderate intensity exercise for CHF patients. The only target heart rate range to prescribe exercise below the ventilatory threshold was 60–80% measured maximum heart rate. Target heart rates calculated from predicted maximum values were higher than those from measured values, and the heart rate reserve method resulted in the highest target heart rates. Cardiac rehabilitation exercise practitioners should be aware that these methods may well result in CHF patients performing heavy rather than moderate exercise.

Diabetes mellitus is caused by an absolute or relative lack of insulin.¹ This article covers people with type 2 diabetes, as most people with type 1 diabetes will be under the care of a secondary care team for at least some of their care. Type 2 diabetes is not primarily about sugar, but about moderating the vascular and neurological damage resulting from chronic hyperglycaemia. Many people with type 2 diabetes will also have components of the metabolic syndrome,² namely hypertension, dyslipidaemia and obesity, all of which need separate and sometimes overlapping interventions.

To establish whether the medication received by patients post-myocardial infarction was prescribed at therapeutic doses, we performed a retrospective audit of discharge summaries. Over three quarters (75.1%) of all patients in the study group were discharged on sub-therapeutic doses of angiotensin-converting enzyme (ACE) inhibitors and beta blockers. In contrast, nearly all (94–97%) patients received a statin at a therapeutic dose. Aspirin and clopidogrel, where prescribed, were also within the therapeutic range in 100% of patients. These findings illustrate the difficulty in optimising the doses of drugs that have a wide range of possible doses during short hospital admissions.

Cardiac magnetic resonance (CMR) has much to offer in the clinical assessment of intra-cardiac space-occupying lesions (SOL). Below we describe the use of CMR as a second-line investigation complementing the use of other imaging modalities, using the example of three patients with atrial SOL. We briefly review the literature and discuss the use of CMR within the context of multi-modality imaging of cardiac SOL.

There are no guidelines on the practice of antibiotic prophylaxis in pacemaker implantation resulting in wide variation in practice. We sought to investigate this and identify areas for further study and improvement. Using an email questionnaire, followed up with a telephone call if no response, all 121 adult National Health Service hospitals in England implanting pacemakers were asked about use of systemic prophylactic antibiotics at implantation. Data were obtained from 61 hospitals (50.4% of total contacted), covering a wide geographic distribution.