Hypertension
All the conflict during the past few years over the subject of blood pressure has revolved around this much overworked word. Hypertension means high pressure, and yet it carries with it a suggestion of high pressure which is harmful to the individual. As a matter of fact hypertension is a compensatory process, it is often a saving process in spite of the fact that it carries possibilities of harm in its possessor. It has been made a fetish, a god to fall down before and worship and it has been the means of holding a torch of fear over a patient which has not been lost on the charlatans. Popularization of blood pressure has brought its crop of evils, no one of which has been as fruitful in dollars to unprincipled quacks as hypertension.
Hypertension is the expression on the part of the circulation to meet new conditions in the tissues so that all tissues will be nourished and all will be enabled to function. Looked at from that point of view it is a conservative process and in many cases it is. It is not an average normal state, but it is normal state for the man who has it in chronic form. Hypertension should be viewed rationally and its proper place in the whole make-up of the patient determined. Hypertension is a relative term. What might be high pressure in a man of sedentary habits who reaches the age of fifty, might not be high pressure in a full blooded formerly athletic man of the same age. Temporary hypertension due to excitement, exercise, etc., must be kept in mind. It is not intended to convey the impression that hypertension is of no moment. It is a matter for investigation, but not a matter to worship as the all-in-all.
Hypertension is, after all, a physiologic response on the part of the organism in order to maintain the circulation in equilibrium in the face of conditions which tend to produce vasoconstriction in large areas and, therefore tend to deprive these areas of blood. That there must be some substance in the blood stream which causes this constriction seems certain. What it is, is not at present known. Recently, Voegtlin and Macht[7] have isolated a crystalline substance from the blood of man and other mammals which they regard as a lipoid and closely related to cholesterin. This substance was recovered by them from the cortex of the adrenal gland. This becomes of added interest in the light of observations made by Gubar (quoted by Voegtlin and Macht). He noted "that the vasoconstricting properties of blood serum vary in different pathologic conditions, being increased in nephritis, for instance, and diminished in others." In some experiments made in the summer of 1913, we found there was no marked difference in the anaphylactic shock produced in half-grown rabbits by the injection of normal and uremic blood serum. As lipoids do not cause anaphylaxis, there should be no difference in the reaction of normal and uremic sera unless in one there was some form of protein not in the other. This does not seem to be the case. The presence of something in the circulation, therefore, produces constriction of vessels. This calls for more force in contraction on the part of the heart. This substance may be of lipoid nature. The continued presence of this hypothetical substance naturally would lead to hypertrophy of the heart.
What makes hypertension of significance is not the hypertension itself, but the fact that it is the expression of processes going on in the body which demand exhaustive investigation. To attach a blood pressure cuff to the arm, find the pressure, and diagnose hypertension is like putting a thermometer under the tongue, noting a rise in the mercury, and diagnosing fever. What causes the hypertension? Can the causes be removed? Those are the really vital questions after the symptom hypertension has been discovered.
All states of hypertension are accompanied by more or less increase of pulse pressure. In other words the systolic pressure is always increased to greater degree than the diastolic pressure. In studies carried out in the wards and Pathological Laboratory of the Milwaukee County Hospital, Milwaukee, we found that in all of the cases of chronic high blood pressure with resulting high pulse pressure four correlated factors were found. If any one of these factors is present, the other three are found.
1. In all high pulse pressure cases there is increase in the size of the cavity of the left ventricle. The ventricle actually contains more blood when it is full, and throws out, therefore, more blood at each systole. The actual volume output is greater per unit of time. Such hearts always show increase in thickness of the ventricular wall. I quite agree with Stone,[8] who says, "It is merely to be emphasized that when the pulse pressure persistently equals the diastolic pressure (high pressure pulse, in other words) with a resulting 50 per cent, overload, which means the expenditure of double the normal amount of kinetic energy on the part of the heart muscle, cardiac hypertrophy has occurred." They are found in aortic insufficiency, in chronic nephritis, in the diffuse fibrous type of arteriosclerosis, and in some cases of exophthalmic goiter. Such a condition occurs temporarily after exercise.
2. In all high pulse pressure cases there is actual permanent increase in diameter of the arch of the aorta. This is a compensating process to accommodate the increased charge from the left ventricle. Smith and Kilgore[9] have shown this to be true in cases of chronic nephritis with hypertension. Their research confirms my own observations. They found dilatation of the arch in (1) syphilis (that is, aortitis); (2) age over 50 (that is, probable factor of arteriosclerosis); (3) other serious cardiac enlargement, and (4) hypertension (with more or less hypertrophy, as in chronic nephritis).
In ten cases showing arches at the upper limit of normal (that is, 6 cm. in diameter) and hypertrophy of the heart, three were chronic mitral endocarditis; one was chronic aortic endocarditis; three were chronic mitral and aortic endocarditis, and there was one each of hyperthyroidism, pericarditis and adherent pericardium.