The pulse is a wave of distension and elongation felt in an artery each time the left ventricle ejects blood into the system. Each contraction of the left ventricle forces about 60 and 80 millilitres of blood through the already full aorta and into the arterial system. The aortic pressure wave is transmitted through the arterial system and can be felt at any point where a superficial artery can be pressed gently against a bone. The number of pulse beats per minute normally represents the heart rate varies considerably in different people and in the same person at different times. Information that may be obtained from the pulse includes:
- The rate at which the heart is beating.
- The regularity of the heartbeat- the intervals between beats should be equal.
- The volume or strength of the beat- it should be possible to compress the artery with moderate pressure,stopping the flow of blood;the compressibility of the blood vessel gives some indication of the blood pressure and the state of the blood vessel wall.
- The tension – the artery wall should feel soft and pliant under the fingers.
In certain circumstances,the pulse may be less than the heart rate. This may occur,for example,if:
- The arteries supplying the peripheral tissues are narrowed or blocked and the blood therefore is not pumped through them with each heartbeat. Provided enough blood is reaching an extremity to nourish it,it will remain pink in colour and warm,even if the pulse cannot be felt.
- There is some disorder of cardiac contraction,eg.atrial fibrillation and the heart is unable to generate enough force,with each contraction,to circulate blood to the peripheral arteries.
