The subject of my todays paper is essential hypertension were thought to be secondary to nephritis or arteriosclerosis. It was only when the sphygmomanometer was brought into clinical use that the condition now known as essential hypertension began to be recognised. The credit of describing these cases of high blood pressure, which are not attended by any significant morphological changes in the kidneys or arteries, goes to Albutt of England and Huchard of France. Albutt names these cases as hyperpiesia.
The definition of essential hypertension is a difficult task. At best it can be defined by a process of exclusion. One may say that by essential hypertension one means those cases of high blood pressure where no previous renal disease can be demonstrated either clinically or anatomically. The term essential hypertension is as a matter of fact a confession of our ignorance. The term essential warns us that we do not know the exact cause of this high blood pressure.
Essential hypertension is quite a common condition met with in practice–both hospital as well as private. It is highly probable that it is increasing in frequency. It is predominantly a disease of the declining phase of life. Almost 90 p.c. of cases are found between the ages of 40 and 70. As has already been stated there is no exact etiology known for the causation of essential hypertension. A large number of hypotheses have been suggested but I will not go into the details of their discussion here.
I will only mention one very significant point regarding these cases. It is with reference to the heredity. The hereditary factor in essential hypertension is very striking and not only does the disease occur in successive generations but in brothers and sisters of a single generation. At least in a large majority of cases essential hypertension arises on the basis of inherited predisposition. Apart from this fact very little is known regarding the true etiology of hypertension.
Usually the course of a case of essential hypertension is an insidious one, lasting for many years, though occasionally one may come across a case where the first and last manifestation is an apoplectic stroke.
Modes of The modes of onset are of various types. The onset. following may be said to be the more common.
The cardiac manifestations are probably the commonest. The patient complains of dyspnoea on exertion or following a heavy meal. Palpitation, precordial oppression or swelling of the feet round about the ankles particularly in the evening after the days work, may be present. Sometimes the disease manifests itself by nervous symptoms which closely resemble functional neurosis and there is every possibility that the case is labelled as such. Of these symptoms headache is the commonest symptom.
The other symptoms are giddiness, noises in the ears and loss of sleep. As already stated the disease might be ushered in by an apoplectic stroke. Epistaxis may be an early symptom. Very rarely the disease manifests itself by uremic symptoms, though nocturia may be an early symptom. Pain in extremities is not uncommonly an early symptom.
The Height of Blood Pressure :- Usually when such a case comes for examination the blood pressure The Height of Blood Pressure is found to be raised. The systolic pressure is above 150 or 160 and the diastolic pressure above 100. Borderline cases where the systolic pressure is about 150 and diastolic about 95, require further observation for being definitely classed as essential hypertension.
The values of the height of blood pressure vary greatly. Rarely the systolic pressure may reach 300 or above and the diastolic above 180. In other cases the systolic may remain 150 and the diastolic round about 100. It is important to remember that the systolic pressure is variable, depending upon many circumstances such as emotional reaction of the patient, etc. The diastolic pressure is the more constant of the two and hence more significant. It may be said that a persistent diastolic pressure of 100 means that the patient has got hypertension.
As I have already stated the course of essential hypertension is usually an insidious one and during the course of the disease many systems of the body get affected and the future symptomatology of essential hypertension then naturally depends upon which system gets affected more.
The three systems which get affected most are the circulatory system, the nervous system and the renal system. We will now consider the manifestations from each of these systems one by one. It goes without saying that all these systems may get more or less affected, varying from patient to patient, giving rise to different symptomatology in each case.
(1) The circulatory system : Due to constant increase of pressure there is in the beginning a hypertrophy of the heart, particularly of the left ventricle. This is manifested by a very important physical sign, namely, the heaving apex beat. By a heaving apex beat is meant one which lifts the palpating finger with abnormally greater force. The first heart sound is usually loud and booming and may seem prolonged. The second sound at the base is usually accentuated. The hypertrophy of the heart may be followed by dilatation, and an apical systolic murmur, due to functional mitral regurgitation, may appear.
Cardiac insufficiency may appear at any period of essential hypertension. The failure may be right sided and then the usual symptoms of right sided failure, namely, those due to venom stasis, such as cyanosis, distension of jugular veins, edema of feet, serous effusions and painful enlargement of the liver occur. In some cases instead of the right side of the heart failing, the left side of the heart may fail. The left sided failure is manifested by attacks of cardiac asthma, pulsus alternans, gallop rhythm and absence of sign of peripheral venom stasis.
Though both these syndromes of the right sided and left sided failure have been separately described usually in a case of essential hypertension, both of them occur simultaneously, and though in the early stages of the disease one may find an isolated left sided failure, in an advanced case right sided failure also supervenes; so that in the end there is insufficiency of the whole heart.
The other important manifestation of hyper tension in the circulatory system is the narrowing of the coronary arteries, so that symptoms of coronary occlusion may be present. Usually whenever there is myocardial injury due to coronary artery disease, there is a striking fall of blood pressure and this is due of the pit falls of diagnosis, as I will mention later.
(2) The next most important system to get is the nervous system. Very few patients suffering from essential hypertension escape the nervous symptoms. In some cases they dominate the picture; in others they are quite insignificant. Out of these nervous symptoms headache is the most important. It may be occipital, frontal or in any part of the head. Sometimes it is unilateral.
Sometimes the headache occurs in attacks coming at irregular intervals. Vertigo is another common symptom, particularly in women. There may be cerebral angiospasm or narrowing of cerebral arteries giving rise to different types of paresis and paralysis depending upon the part of the brain affected. One of the important or usually a fatal manifestation which occurs in the nervous system is cerebral haemorrhage causing apoplexy.
(3) The third important system that gets affected is the renal system. It must be very strongly emphasised here that only a small proportion of cases (about 10 p.c.) of essential hypertension succumb to the disease as a result of damage to the functional capacity of the kidneys. The large majority of cases pass through the course of the disease without any damage to the kidneys. Kidney damage is of course manifested by the appearance of uremic symptoms. It can be diagnosed by doing the kidney function test, the best of which is probably the urea clearance test.
Changes in the fundus of the eye are very common in cases of essential hypertension and are often of diagnostic and prognostic significance. There is narrowing of the arteries papilloedema and retinal haemorrhages which are often flame shaped.
Summarising the whole course of cases of essential hypertension one may say that it can be divided into four types (1) Cases which suffer from hypertension for a number of years and ultimately die of a disease which is entirely unconnected with the hypertension (2) Cases which develop a myocardial failure, first one-sided and ultimately of the whole heart. (3) Cases which die of cerebral haemorrhage which may or may not be preceded by attacks of angio-spasm. (4) Cases which develop the failure of renal function–and this occurs only in a minority of cases–and ultimately die of uraemia. Putting the whole thing in a nut shell one may say that in some cases of hypertension the pump may fail, in others the tube may fail and in still others the filter may fail.