The systole is not altered in length, but the diastole is very much prolonged, and since this is the period not only of cardiac rest but also of cardiac "feeding" - the coronary vessels being compressed and occluded during systole - the result is greatly to benefit the nutrition of the cardiac muscle.
The bearing of this fact on cases of cardiac dilatation is evident.
It can only be laid down that the drug is a valuable though temporary stimulant in emergencies, and that its use as a plaster or internally often relieves cardiac pain.
The medieval Jews also held that there is a cardiac demon in wine which takes possession of drunken men; and the Mahommedan prohibition of wine-drinking is based on a similar superstition.
Over the right part the mucous membrane has a greyish-red colour and a velvety appearance, and contains numerous peptic glands, which are wanting in the cardiac portion.
The drug is not a true specific, as quinine is for malaria, since it rarely, if ever, prevents the cardiac damage usually done by rheumatic fever; but it entirely removes the agonizing pain, shortly after its administration, and, an hour or two later, brings down the temperature to normal.
When the growth is at the cardiac end of the stomach, blocking the gullet and causing slow starvation, the abdomen may advisedly be opened, and, the stomach having been fixed to the surface-wound, a permanent opening may be arranged for the introduction of an adequate amount of food.
Ten to twenty minims of ether, subcutaneously injected, constitute perhaps the most rapid and powerful cardiac stimulant known, and are often employed for this purpose in cases of syncope under anaesthesia.
In the dropsy of cardiac disease, owing to the deficient oxidation from stagnation of blood, metabolic products must accumulate in the tissues; also lymph return must be impeded by the increased pressure in the veins and so dropsy results (Wells).
All potassium salts if taken in large doses are cardiac depressants, they also depress the nervous system, especially the brain and spinal cord.
Avellanarius, the common dormouse, distinguished by the cylindrical bushy tail, and thickened glandular walls of the cardiac extremity of the oesophagus; thirdly, Eliomys, containing several species, with tufted and doubly vaned tails, simple stomachs and smaller molar teeth, having concave crowns and faintly marked enamel-folds; and lastly, the African Graphiurus, represented by several species, with short cylindrical tails ending in a pencil of hairs, and very small molars almost without trace of enamel-folds.
The cardiac portion of the complex stomach has a horny layer, and there is a caecum.
Later in its action, the drug depresses the intra-cardiac motor ganglia, causing prolongation of diastole and finally arrest of the heart in dilatation.
Not only is the respiratory centre stimulated but the cardiac centre is acted upon both directly by the drug and indirectly for a time by the enormous rise in blood pressure due to the contraction of the arterioles all over the body.
Of the hydrochloride may stimulate the cardiac action.
Digitalis contains four important glucosides, of which three are cardiac stimulants.
Digitonin, on the other hand, is a cardiac depressant, and has been found to be identical with saponin, the chief constituent of senega root.
The cardiac contractions become irregular, the ventricle assumes curious shapes - "hour-glass," &c. - becomes very pale and bloodless, and finally the heart stops in a state of spasm, which shortly afterwards becomes rigor-mortis.
Clinically it is to be observed that the drug is cumulative, being very slowly excreted, and that after it has been taken for some time the pulse may become irregular, the blood-pressure low, and the cardiac pulsations rapid and feeble.
The initial action of digitalis is a stimulation of the cardiac terminals of the vagus nerves, so that the heart's action is slowed.
Thereafter follows the most important effect of the drug, which is a direct stimulation of the cardiac muscle.
This can be proved to occur in a heart so embryonic that no nerves can be recognized in it, and in portions of cardiac muscle that contain neither nervecells nor nerve-fibres.
The uses of atropine in cardiac affections are still obscure and dubious.
As it does not depress the heart when used in medicinal doses, it may be given to patients suffering from cardiac disease.
When this continues for a length of time it tends by itself to cause deterioration of the blood-vessels and leads to death either by cerebral apoplexy or by cardiac failure.
Rest in bed should be insisted upon for a longer time than appears actually required, because acute rheumatism tends to bring on cardiac changes, and is more likely to do this when the heart is excited than when the patient is kept at rest.
Exercises, passive and active, are also used in diseases of the joints, as well as massage and baths, but exercises and training are even more important in cases of cardiac disease.
In most Decapods the " stomach " or dilated portion of the fore-gut is divided into two chambers, a large anterior " cardiac " and a smaller posterior " pyloric."
There may be bleeding from the nose, cutaneous congestion, deafness, blindness, coma or delirium, and even death from cardiac failure.
Use hot bottles and stimulants, especially trying to counteract the cardiac depression by atropine, caffeine, strophanthin, &c.
It used to be stated that these drugs are marked cardiac depressants; and the heart being invariably implicated in rheumatic fever, it is supposed that these drugs must be given with great caution.