Applications of PET to cardiology

There has been much discussion about the dual roles of research and clinical PET. A number of centres have installed PET systems purely for clinical diagnosis, mainly in the determination of myocardial viability, but also for applications in oncology and neurology. Diagnostic testing of this kind is clearly derived from original work carried out at research establishments. The terms research and clinical should, therefore, be regarded as complementary. In the author's institution the balance...

Drug related diseases

Ergot alkaloid heart disease Methysergide and ergotamine are two classical drugs that are used in the prophylaxis and treatment of migraine headaches. Ergotamine is believed to relieve migraine by inducing vasoconstriction of the cerebrovascular bed, while methysergide achieves a similar eVect by its antiserotoninergic properties. They are ergot alkaloid derivatives, and both share a common chemical structure to the neurohormone serotonin. Serotonin is the agent responsible for valve disease in...

Acute coronary syndromes presentationclinical spectrum and management

Acute coronary syndromes define a spectrum of clinical manifestations of acute coronary artery disease. These extend from acute myocardial infarction through minimal myocardial injury to unstable angina. This spectrum shares common underlying patho-physiological mechanisms. The central features consist of fissuring or erosion of atheromatous plaque with superimposed platelet aggregation and thrombosis. This is complicated by microfragmentation and distal embolisation with alterations in...

Cardiac valve disease associated with the antiphospholipid syndrome

The antiphospholipid (aPL) syndrome is an entity characterised by vascular thrombosis with frequent heart involvement, particularly valvar lesions.19 The syndrome is caused by the appearance of circulating aPL antibodies, which are spontaneously acquired circulating immunoglobulins directed against negatively charged phospholipids. aPL antibodies were initially found in sera of patients with systemic lupus erythematosus. They have since been found occasionally in other connective tissue...

Ischaemic heart disease

Overt hypothyroidism is associated with hyper-lipidaemia and coronary artery disease. Approximately 3 of patients with longstanding hypothyroidism report angina, and a similar proportion report it during treatment with thy-roxine. In most patients the angina does not change, diminishes or disappears when thyrox-ine is introduced however, it may worsen and up to 40 of those patients who present with hypothyroidism and angina cannot tolerate full replacement treatment. Moreover, myocardial...

Dilated cardiomyopathy

The pathophysiological entity dilated cardiomyopathy (DCM) is heterogeneous with regard both to its pathogenesis and its morphology. Common to the whole group is a poorly contracting dilated left ventricle with a normal or reduced left ventricular wall thickness. The lack of an increase in left ventricular wall thickness tends to mask a significant increase in left ventricular mass. In the terminal stages thrombus may develop in the apices of both ventricles. The histological changes within the...

Which type of hyperthyroidism

Although there are features which help to distinguish between the two types of hyperthy-roidism (table 35.1), the differentiation may be diYcult and in some patients both mechanisms may be operating. In such circumstances it is sensible to institute a trial of carbimazole and to withdraw the drug after 3-4 months. If the patient remains euthyroid or becomes hypothyroid the diagnosis is likely to be type II hyperthyroidism evidence of persistent hyperthyroidism suggests a diagnosis of type I...

Amiodarone induced hypothyroidism

Amiodarone may cause hypothyroidism in patients with pre-existing Hashimoto's thyroiditis. However, the presence of a raised serum TSH concentration before or during treatment is not a contraindication to the use of amiodarone as the thyroid failure is readily treated with thyroxine. Amiodarone will induce hyper- or hypothyroidism in up to 20 of subjects, and thyroid dysfunction may persist for several months or develop for the first time after the drug has been stopped. Thyroid status should...

Myocardial infarction outside hospital

In the most recent study performed in the UK,1, 74 of 1589 deaths from acute coronary heart attacks in people under 75 years of age occurred outside hospital the proportion of out-of-hospital to total deaths varied inversely with age from 91 at age < 55 years to 67 at age 70-74 years (fig 6.1). Had the lives of 5 of potential victims of out-of-hospital sudden death not been saved by advanced life support given by ambulance staff, the proportion of out-of-hospital deaths to total deaths would...

Other possible models in the evolution of heart diseases and limitations of the studies

In Europe there are more than 20 large longitudinal studies in which the main focus has been or is to study prenatal or early life factors in relation to adult disease risk. Many of them are historical cohort studies, or data collection has started after birth retrospectively at various points of life. The most important historical cohort studies, from the point of view of the fetal origin hypothesis, are the Hertfordshire,4 14 Preston,12 21 and Sheffield8 studies, as well as the Helsinki27 and...

Biological programming a new theoretical model about the aetiology of heart disease

The dawn of modern epidemiology came after the second world war, first with ecological studies comparing CVD incidence and mortality, and subsequently multicentre cross sectional and follow up studies on CVD.w3 The studies showed that populations with high CVD mortality have high cholesterol and high blood pressure, and that smoking and obesity are common among these populations.4 This led to the lifestyle model in understanding the aetiology of chronic diseases, where the key issues are health...

Risk stratification

SPECT perfusion imaging is also useful for the purpose of non-invasive risk stratification to identify patients who have the greatest risk for subsequent death and myocardial infarction. High risk (> 3 annual mortality) features on stress SPECT perfusion imaging Post-stress ejection fraction < 35 (technetium-99m) Stress induced large perfusion defect Stress induced multiple perfusion defects of moderate size Large, fixed perfusion defect with left ventricular dilatation or increased lung...

Acute myocardial infarction

It is difficult now to perceive why coronary thrombosis was regarded 25 years ago as an inconstant and irrelevant consequence of acute infarction rather than its prime cause. Once angiography was carried out soon after the onset of infarction, and it was realised that the subtending artery was totally blocked but spontaneously reopened with time in many cases (and that this reopening was accelerated by fibrinolytic treatment), thrombosis was seen as a major causal factor in occlusion. Suddenly...

Over replacement with thyroxine

There is some concern that administering thy-roxine in a dose which suppresses serum TSH may provoke significant cardiovascular problems, including abnormal ventricular diastolic relaxation, a reduced exercise capacity, an that a suppressed serum TSH concentration in a patient taking thyroxine in whom serum T3 is unequivocally normal is a risk factor for atrial fibrillation. Figure 35.3. Sequential chest x rays from a patient with longstanding hypothyroidism that was complicated by congestive...

Degenerative valve disease

Although there has been a dramatic reduction in rheumatic valve disease in the industrialised countries over the past 30 years, there has not been a similar reduction in valve surgery. This is because the types of patients being referred for surgery have changed. The significant increase in life expectancy in developed countries partly accounts for this change in aetiology, especially in aortic valve disease. In one surgical series over a five year period (from 1981 to 1985), it was found that...

Left ventricular restoration

Patients with large left ventricular aneurysms gain symptomatic relief from simple linear aneurysmectomy. So called ventricular restoration has recently extended from scarred paradoxical segments to akinetic areas which were not previously thought suitable for surgery.13 The goal of surgical reversal of remodelling is to exclude the infarcted septum and free wall and reshape the left ventricle from globular to elliptical without critically reducing Table 11.3 Decision making in the surgery of...

The atherosclerotic plaque

Atherosclerosis begins as a subendothelial accumulation of lipid laden, monocyte derived foam cells and associated T cells which form a non-stenotic fatty streak. With progression, the lesions take the form of an acellular core of cholesterol esters bounded by an endothelial-ised fibrous cap containing vascular smooth muscle cells (VSMC) and inflammatory cells, predominantly macrophages with some T cells and mast cells, which tend to accumulate at the shoulder regions of the plaque. Also...

VT related to regions of scar

The majority of sustained monomorphic VTs are caused by re-entry involving a region of ventricular scar. The scar is most commonly caused by an old myocardial infarction, but arrhythmogenic right ventricular dysplasia, sarcoidosis, Chagas' disease, other non-ischaemic cardiomyopathies and surgical ventricular incisions for repair of tetralogy of Fallot, other congenital heart diseases, or ventricular volume reduction surgery (Batista procedure) can also cause scar related re-entry. Dense...

Other causes of acute myocarditis

Lyme disease caused by Borrelia burgdorferi, a tick borne organism carried by deer, may cause an acute myocarditis, typically with a long PR interval as occurs with acute rheumatic fever. Left ventricular dysfunction is usually transient but the organism has been cultured from endomyocardial biopsy material in a patient with a dilated cardiomyopathy. Chagas' disease, common in rural parts of Central and South America, results from infection by Trypanosoma cruzi. Although best known as a cause...

Acute myocardial infarction in hospital

Course no attempt at distinction between infarction and electrical death is possible in purely epidemiological studies. Yet another problem in identification of the natural history of acute myocardial infarction is that fully 25 of non-fatal infarctions are silent.8 Silent infarction can be detected only when a subject is seen more than once at annual intervals or longer, and an ECG performed on the second occasion shows new pathological Q waves. Most clinicians can remember such cases, but an...

Viral infection and acute myocarditis

Acute myocarditis in animals such as mice coxsackie and dogs parvovirus . What occurs in other animals is likely to occur in man. Coxsackie genomic material is found in about a third of human cases of acute myocarditis using PCR technology on myocardial tissue. The younger the subject the more likely is virus to be found. One facet of viral myocarditis in experimental animals is that viral replication ceases before the myocyte damage occurs. It is therefore rarely possible to culture...

The balance of atherosclerosis

Atherosclerosis is a dynamic balance between the destructive influence of inflammatory cells and the reactive, stabilising effects of VSMCs. The balance is biased in favour of plaque rupture by factors such as high low density lipoprotein LDL cholesterol, lipid peroxidation and, probably, genetic variability in the inflammatory molecules involved. For example, there is a correlation between plaque progression and a polymorphism in the stromelysin-1 gene promoter. Also, it is entirely plausible...