Saturday, 5 September 2015

Alcohol and Left Ventricular Hypertrophy

Consumption of high intakes of alcohol can cause damage to the liver if consumed in high amounts over long periods of time. In addition alcohol can induce certain vitamin deficiencies, particularly thiamine, and can cause changes to cognition, motivation and memory. The role of alcohol is preventing cardiovascular disease is controversial, mainly due to the dose response relating to its consumption. Generally low and high intakes do not produce beneficial effects, but moderate consumption has been shown to produce beneficial effects. The benefits of alcohol in terms of cardioprotection have been suggested to relate to its ability to raise plasma levels of high density lipoprotein (HDL). However, alcohol consumption raises levels of HDL2, a fraction that is not associated with a reduced risk of cardiovascular disease. More likely alcohol decreases the thrombotic tendencies of blood cells, an effect that is thought to provide a reduction in myocardial infarction risk for 24 hours post consumption.
Even low intake of alcohol may induce left ventricular hypertrophy and this could suggest that all alcohol is bad for the health. As few as two drinks per day if consumed regularly may produce changes to the heart structure around the left ventricle. Such hypertrophy of the left ventricle is associated with detrimental rhythmic changes to the hearts beating pattern and may increase the risk of sudden cardiac death. This effect appears to show a dose response and so higher intakes of alcohol significantly accelerate the structural changes. These structural changes to the heart are magnified if other risk factors such as high blood pressure or obesity are present. Left ventricular hypertrophy is often detected with electrocardiograms or the more sensitive echocardiograms. Left ventricular hypertrophy likely occur from drinking alcohol because alcohol consumption can increase blood pressure. If this is true it would suggest that other lifestyle habits can modify the association.
Exercise is also known to cause left ventricular hypertrophy. This is a physiological response to the increased demands on the heart for the circulation of blood during physical activity. Just why the left ventricular hypertrophy associated with drinking is detrimental, but that associated with exercise is beneficial, is never fully explained. This likely relates to the fact that those who consume alcohol and who experience left ventricular hypertrophy often have other lifestyle habits that increase the risk of cardiovascular disease. In contrast those who exercise regularly likely have other lifestyle habits that protect from cardiovascular disease. The left ventricular hypertrophy associated with exercise is also not associated with high blood pressure. Although exercise raised blood pressure during activity, following activity blood pressure falls such that the baseline level is lower than in non exercising controls. However, alcohol raises blood pressure, and this is a serious risk factor for cardiovascular disease and sudden death.

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