Disturbances of the Heart | Page 6

Klewitz: Deutsch. Arch. f. klin. Med. 1913, cxii, 38.] found that the average pulse rate of normal individuals while awake and active was 74 per minute, but while asleep the average fell to 59 per minute. He found also that if a state of perfect rest could be obtained during the waking period, the pulse rate was slowed. This is also true in cases of compensated cardiac lesions, but it was not true in decompensated hearts. He found that irregularities such as extrasystoles and organic tachycardia did not disappear during sleep, whereas functional tachycardia did.
It is well known that high blood pressure slows the pulse rate; that low blood pressure generally increases the pulse rate, and that arteriosclerosis, or the gradual aging of the arteries, slows the pulse, except when the cardiac degeneration of old age makes the heart again more irritable and more rapid. The rapid heart in hyperthyroidism is also well understood. It is not so frequently noted that hypersecretion of the thyroid may cause a rapid heart without any other tangible or discoverable thyroid symptom or symptoms of hyperthyroidism. Bile in the blood almost always slows the pulse.
INTERPRETATION OF TRACINGS
The interpretation of the arterial tracing shows that the nearly vertical tip-stroke is due to the sudden rise of blood pressure caused by the contraction of the ventricles. The long and irregular down-stroke means a gradual fall of the blood pressure. The first upward rise in this gradual decline is due to the secondary contraction and expansion of the artery; in other words, a tidal wave. The second upward rise in the decline is called the recoil, or the dicrotic wave, and is due to the sudden closure of the aortic valves and the recoil of the blood wave. The interpretation of the jugular tracing, or phlebogram as the vein tracing may be termed, shows the apex of the rise to be due to the contraction of the auricle. The short downward curve from the apex means relaxation of the auricle. The second lesser rise, called the carotid wave, is believed to be due to the impact of the sudden expansion of the carotid artery. The drop of the wave tracing after this cartoid rise is due to the auricular diastole. The immediate following second rise not so high as that of the auricular contraction is known as the ventricular wave, and corresponds to the dicrotic wave in the radial. The next lesser decline shows ventricular diastole, or the heart rest. A tracing of the jugular vein shows the activity of the right side of the heart. The tracing of the carotid and radial shows the activity of the left side of the heart. After normal tracings have been carefully taken and studied by the clinician or a laboratory assistant, abnormalities in these readings are readily shown graphically. Especially characteristic are tracings of auricular fibrillation and those of heart block.
TESTS OF HEART STRENGTH
If both systolic and diastolic blood pressure are taken, and the heart strength is more or less accurately determined, mistakes in the administration of cardiac drugs will be less frequent. Besides mapping out the size of the heart by roentgenoscopy and studying the contractions of the heart with the fluoroscope, and a detailed study of sphygmographic and cardiographic tracings, which methods are not available to the large majority of physicians, there are various methods of approximately, at least, determining the strength of the heart muscle.
Barringer [Footnote: Barringer, T. B., Jr.: The Circulatory Reaction to Graduated Work as a Test of the Heart's Functional Capacity, Arch. Int. Med., March, 1916, p. 363.] has experimented both with normal persons and with patients who were suffering some cardiac insufficiency. He used both the bicycle ergometer and dumb-bells, and finds that there is a rise of systolic pressure after ordinary work, but a delayed rise after very heavy work, in normal persons. In patients with cardiac insufficiency he finds there is a delayed rise in the systolic pressure after even slight exercise, and those with marked cardiac insufficiency have even a lowering of blood pressure from the ordinary level. They all have increase in pulse rate. He quotes several authorities as showing that during muscle work the carbon dioxid of the blood is increased in amount, which, stimulating the nervous centers controlling the suprarenal glands, increases the epinephrin content of the blood. The consequence is contraction of the splanchnic blood vessels, with a rise in general blood pressure. Also, the quickened action of the heart increases the blood pressure. After a rest from the exercise, the extra amount of carbon dioxid is eliminated from the blood, the suprarenal glands decrease their activity, and the blood pressure falls.
Nicolai and Zuntz [Footnote: Nicolai anal Zuntz: Berl. klin. Wehnschr., May 4, 1914, p. 821.] have shown that with the first strain of heavy