24. The arterial and the venous pulse. Basic principles of hemodynamics.

When we talk about the pulse, we refer to the arterial pulse. The arterial pulse is the periodic, tactile vibration which can be felt at different points on the body. The pulse is the result of the heart pumping. When the heart pumps, a pressure wave propagates along the arterial blood vessels, and when this pressure wave reaches a pulse point a pulse can be felt.

The pulse rate is the same as the heart rate in normal cases.

The arterial pulse wave which propagates along the arterial blood vessels becomes smaller and smaller as it travels along the arteries. For this reason, there is no pulsatile flow, only continuous flow, at the level of the capillaries and veins.

Palpation points of the pulse

The pulse can be felt at many points on the body. It can only be felt on arteries which are near to the surface of the body, and which lie above bony surfaces.

Most important palpation points:

  • Temporal artery
  • Carotid artery
  • Axillary artery
  • Cubital artery
  • Radial artery
  • Ulnar artery
  • Femoral artery
  • Popliteal artery
  • Dorsalis pedis artery

When palpating a pulse, three fingers should be used.

Characteristics of the pulse

The pulse has many characteristics. It can be regular, irregular, hard, soft, etc. Below is a table of the important different characteristics of the pulse:

Quality

Characteristic

Rhythm

Regular Irregular (arrhythmic)

Rate

Frequens (tachycardic) Rarus (bradycardic)

Hardness

Durus (hard)

Mollis (soft)

Amplitude/size/strength Altus (large amplitude)

Parvus (small amplitude)

Equality Equalis

Inequalis

Pulse wave increase Celer (fast)

Tardus (slow)

Arterial pulse curve

The way the arterial pulse varies with time can be drawn as a curve. The curve looks like this:

The ascending part of the pulse curve is called the anacrot and the descending part is called the catacrot. On the catacrot there is the dicrotic notch, also called the incisura, which occurs when the aortic valve closes.

The amplitude of the arterial pulse curve is not affected by changes in the frequency.


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23. Arterial blood pressure. Determinants of normal arterial blood pressure

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25. Circulation through the capillaries

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