“The first phase is due to the sudden expansion of the collapsed portion of the artery below the cuff and to the rapidity of the blood flow. This causes the first sharp clicking sound which measures the systolic pressure.
“The second, or murmur and sound phase is due to the whorls in the blood stream, as the pressure is further released and the part of the artery below the cuff begins to fill with blood.
“The third tone phase is due to the greater expansion of the artery and to the lowered velocity in the artery. A loud tone may be produced by a stiff artery and a slow stream or by an elastic artery and a rapid stream. This tone is clear cut, and in general is louder than the first phase.
“The fourth phase is a transition from the third, and becomes duller in sound as the artery approaches the normal size.
“The fifth phase, no-sound phase, occurs when the pressure in the cuff exerts no compression on the artery and the vessel is full throughout its length.”
He also says that blood pressure always depends on four factors, viz.:
1. Cardiac energy.
2. Peripheral resistance.
3. Elasticity of the arterial walls.
4. The amount of blood in circulation.
It is very important to remember these and to give due value to each of them. With regard to No. 4, it is doubtful if this is of as much importance as has been thought or as one would at first think; the mass of blood in the body has such a large reserve of stowage room in the muscles and in the internal viscera, that its effect on general arterial pressure must be slight. The viscosity of this fluid is probably of far more importance. If one bleeds a case of high pressure freely, the pressure will fall, but only for a short time; the blood is thinned, but the loss in mass is quickly restored by absorption from the watery tissues of the body, and in a very few days the viscosity returns to its former point. Bleeding is thus very good for emergencies, such as threatening apoplexy or cardiac dyspnœa, but is of little permanent use in the routine treatment of high pressure.
Sir Clifford Allbutt, wisely and correctly, I think, divides most examples of abnormal high pressure into hyperpiesis, which describes this symptom alone, and into senile atheroma. Clinically this is important, for hyperpiesis, which generally comes on about fifty to sixty, is a very serious disease, which, untreated, destroys life in a few years, whereas senile atheroma may go on till advanced old age, crippling energy perhaps, but in many cases hardly shortening life at all. The former generally ends in cerebral hæmorrhage, cardiac degeneration or Bright’s disease, but senile atheroma may escape all of these. In hyperpiesis raised pressure is continuous and tends steadily to increase; in atheroma there are times of high pressure, but as the disease advances the pressure is often normal or subnormal, its gravity depending much on the seat of the atheroma.
Are we justified in regarding arterio-sclerosis as a true disease? I think not. One cannot justly compare it with entity diseases, such as the acute infections, as cancer, as tuberculosis, or the diseases that affect the brain and the spinal cord. It is, I think, one of the penalties of an artificial over-civilization, of social, business and competitive pressure, unwise in quantity and unscientific in method. Unfitted, as yet, in development, and lacking the necessary knowledge, men strive after a higher stage of evolution, or after illusions which they think to be so. For a while they seem to succeed, but involution and premature degeneration are the inevitable consequences. To attain their “ambitious” ends they live and work intensely, stoking their furnaces with far too much food, alcohol and other unnatural stimulants. Intemperate in work, intemperate in living, prodigal in waste, they come to an untimely end.