Disturbances of the Heart / Discussion of the Treatment of the Heart in Its Various Disorders, With a Chapter on Blood Pressure

by Oliver T. Osborne

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 work the heart increases in size, but it soon becomes normal, or even smaller, as it more strenuously contracts, and the cavities of the heart will be completely emptied at each systole. If the work is too heavy, and the systolic blood pressure is rapidly increased, it may become so great as to prevent the left ventricle from completely evacuating its content. The heart then increases in size and may sooner or later become strained; if this strain is severe, an acute dilatation may of course occur, even in an otherwise well person. Such instances are not infrequent. A heart which is already enlarged or slightly dilated and insufficient, under the stress of muscular labor will more slowly increase its forcefulness, and we have the delayed rise in systolic pressure.

Barringer concludes that:

The pulse rate and the blood pressure reaction to graduated work is a valid test of the heart's functional capacity. If the systolic pressure reaches its greatest height not immediately after work, but from thirty to 120 seconds later, or if the pressure immediately after work is lower than the original level, that work, whatever its amount, has overtaxed the heart's functional capacity and may be taken as an accurate measure of the heart's sufficiency.

In another article, Barringer [Footnote: Barringer, T. B., Jr.: Studies of the Heart's Functional Capacity as Estimated by the Circulatory Reaction to Graduated Work, Arch. Int. Med., May, 1916, p. 670.] advises the use of a 5-pound dumb-bell extended upward from the shoulder for 2 feet. Each such extension represents 10 foot- pounds of work, although the exertion of holding the dumb-bell during the nonextension period is not estimated. He believes that if circulatory tire is shown with less than 100 foot-pounds per minute exercise, other signs of cardiac insufficiency will be in evidence. He also believes that these foot-pound tests can be made to determine whether a patient should be up and about, and also that such graded exercise will increase the heart strength in cardiac insufficiency.

Schoonmaker, [Footnote: Schoonmaker: Am. Jour. Med. Sc., October, 1915, p. 582.] after studying the blood pressure of 127 patients, concludes that myocardial efficiency will be shown by a comparison of the systolic and diastolic blood pressure, with the patient lying down and standing up, after walking a short distance. Such slight exercise should not cause any subjective symptoms, either dyspnea, palpitation or chest pain. If the heart muscle is in good condition, the systolic pressure should remain the same after this slight exertion and these changes in posture. When the heart is good, there may be slight increased pressure when the patient is standing. If, after this slight exercise in the erect posture, the systolic pressure is diminished, the heart muscle is defective.

Martinet [Footnote: Martinet: Presse med., Jan. 20, 1916.] tests the heart strength as follows: He counts the pulse until for two successive minutes there is the same number of beats, first when the patient is lying down, and then when he is standing. He also takes the systolic and diastolic pressures at the same time. He then causes the person to bend rapidly at the knees twenty times. The pulse rate and the blood pressure are then taken each minute for from three to five minutes. The person then reclines, and the pulse and pressure are again recorded, Martinet says that an examination of these records in the form of a chart gives a graphic demonstration of the heart strength. If the heart is weak, there are likely to be asystoles, and tachycardia may occur, or a lowered blood pressure.

Rehfisch [Footnote: Rehfisch: Berl. klin. Wehnsehr., Nov. 29, 1915] states that when a healthy person takes even slight exercise, the aortic closure becomes louder than the second pulmonic sound, showing an increased systolic pressure. If the left ventricle is unable properly to empty itself against the increased resistance ahead, the left auricle will contain too much blood, and with the right ventricle sufficient, there will be an accentuation of the second pulmonic sound and it may become louder than the second aortic sound, showing a cardiac deficiency. If, on the other hand, the right ventricle becomes insufficient, or is insufficient, the second pulmonic sound is weaker than normal, and the prognosis is bad.

Barach [Footnote: Barach: Am. Jour. Med. Sc., July, 1916, p. 84] presents what he terms "the energy index of the circulatory system." He has examined 742 normal persons, and found that the pressure pulse was anywhere from 20 to 80 percent of the diastolic pressure in 80 per cent of his cases, while the average of his figures gave a ratio of 50 percent; but he does not believe that it holds true that in a normal person the pressure pulse equals 50 percent of the diastolic pressure. Barach does not believe we have, as yet, any very accurate method of determining the cardiac strength or circulatory capacity for work. He does not believe that the estimate of the pressure pulse is indicative of cardiac strength. He believes that the important factors in the estimation of the circulatory strength are the systolic pressure, which shows the power of the left ventricle, the diastolic pressure, which shows the intravascular tension during diastole as well as the peripheral resistance, and the pulse rate, which designates the number of times the heart must contract during a minute to maintain the proper flow of blood. He thinks that these three factors are constantly adapting themselves to each other for the needs of the individual, and he finds, for instance, that when the left ventricle is hypertrophied and the output of blood is therefore greater, then the pulse will be slowed. His method of estimation is as follows: For instance, with a systolic pressure of 120 mm. and a diastolic pressure of 80 mm., each pulse beat will represent an energy equal to lifting 120 mm. plus 80 mm., which equals 200 mm. of mercury, and with seventy-two pulse beats the force would be 72 X 200, which equals 14,400 mm. of mercury. He finds an average circulatory strength based on examining 250 normal individuals by the index, which he terms S, D, R (systolic, diastolic rate), to be 20,000 mm. of mercury per minute.

Katzenstein [Footnote: Katzenstein: Deutsch. med. Wehnsehr., April 15, 1915.] finds, after ten years of experience, that the following test of the heart strength is valuable: He records the blood pressure and pulse, and then compresses the femoral artery at Poupart's ligament on the two sides at once. He keeps this pressure up for from two to two and one-half minutes, and then again takes the blood pressure. With a sound heart the blood pressure will be higher and the pulse slower than the previous record taken. If the blood pressure and pulse beat are not changed, it shows that the heart is not quite normal, but not actually incompetent. When the blood pressure is lower and the pulse accelerated, he believes that there is distinct functional disturbance of the heart and loss of power, relatively to the change in pressure and the increase of the pulse rate. He further believes that a heart showing this kind of weakness should, if possible, not be subjected to general anesthesia.

Stange [Footnote: Stange: Russk. Vrach, 1914, xiii. 72.] finds that the cardiac power may be determined by a respiratory test as follows: The patient should sit comfortably, and take a deep inspiration; then he should be told to hold his breath, and the physician compresses the patient's nostrils. As soon as the patient indicates that he can hold his breath no longer, the number of seconds is noted. A normal person should hold his breath from thirty to forty seconds without much subsequent dyspnea, while a patient with myocardial weakness can hold his breath only from ten to twenty seconds, and then much temporary dyspnea will follow. Stange does not find that pulmonary conditions, as tuberculosis, pleurisy or bronchitis, interfere with this test.

Williamson [Footnote: Williamson: Ant. Jour. Med. Sc., April, 1915, p. 492.] believes that we cannot determine the heart strength accurately unless we have some method to note the exact position of the diaphragm, and he has devised a method which he calls the teleroentgen method. With this apparatus he finds that a normal heart responds to exercise within its power by a diminution in size. The same is true of a good compensating pathologic heart. He thinks that a heart which does not so respond by reducing its size after exercise has a damaged muscle, and compensation is more or less impaired.

Practical conclusions to draw from the foregoing suggestions are:

1. An enlargement of the heart after exercise can be well shown only by fluoroscopic examination, and then best by some accurate method of measurement.

2. The blood pressure should be immediately increased by exercise, and after such exercise should soon return to the normal before the exercise. If it goes below the normal the heart is weak, or the exercise was excessive.

3. The pulse rate should increase with exercise, but not excessively, and should within a reasonable time return to normal.

4. The stethoscope will show whether or not the normal sounds of the heart become relatively abnormal after exercise. If such was the fact, though the abnormality was not permanent, heart insufficiency is more or less in evidence.

5. The relation of pulse rate to blood pressure should always be noted, and the working power of the heart may be estimated according to Barach's suggestion.

6. The dumb-bell exercise tests suggested by Barringer (only, the dumb-bells may be of lighter weight) are valuable to note the gradual improvement in heart strength of patients under treatment.

7. The holding the breath test is very suggestive of heart efficiency or weakness, but a series of tests must be made before its limitations are proved.