Heart and circulation, acting upon the heart by either stimulating or depressing its activity depending upon the need. The precise mode of action which results in the dilating of the coronary blood supply and the tendency to slow down or stabilize the contractility of the heart muscle is not yet fully understood, but it is safe to use as a long-term treatment for a weak or failing heart, and has a beneficial effect on cardiac arrhythmia, especially extra systoles and paroxysmal tachycardia. Also a useful diuretic. Other clinical observations included a reduction in elevated blood levels of pyruvic and lactic acid, normalization of prolonged systole and prevention of ECG changes due to hypoxia. As a tonic for the circulatory system Crataegus finds its primary use in the treatment of hypertension, atherosclerosis and angina pectoris. It is also applicable to peripheral circulatory conditions, such as intermittent claudication and Raynaud`s disease. The flavonoids in Crataegus are vasodilatory, as is the condensed tannin phlobaphene. These dilate the peripheral blood vessels and have a specific action on the coronary circulation. The cyanogenic glycosides are sedative and increase the parasympathetic (vagal) tone of the heart, thus slowing it down. Trimethylamine stimulates the pulse rate slightly, and has a peripheral vasoconstrictor effect. The sedative effects of the cyanogenic glycosides combine with the vasodilatory effects to lower high blood pressure, but the cardiotonic activity actually helps to raise low blood pressure. Crataegus does not contain digitalis-like substances, but is a gentle remedy requiring extended use. It should also be used in the follow-up therapy of myocardial infarction. Both the flowers and the berries are astringent and a decoction of these will help ease sore throats.