A site for medical students - Practical,Theory,Osce Notes


What is pulse deficit?

Definition of pulse deficit- it is the difference between the heart rate and the pulse rate. It is commonly found in atrial fibrillation and multiple ectopic beats.
Following are the method of detection of pulse deficit ;
1.First you should count the heart rate for one minute and then the pulse rate for next one minute (examination in two different cardiac cycles) .This is the  commonly practised method.
2.One examiner counts the heart rare and the other examiner counts the pulse rate at the sametime (using single cardiac cycle) for one minute.
3.Examiner may put his stethoscope at the apex and simultaneously count the dropped beats in the pulse (using single cardiac cycle) for one minute.
What is an ectopic beat?
In ectopic rhythm, the impulse originate from sites other than the SA node, and this may arise from the atrial wall, AV node or ventricular wall.
The ectopic beat is 
  • Small 
  • It ocurs prematurely
  • It is followed by a compensatory pause.
Palpate the pulse at the wrist , small pause followed by small beat, big raise is followed by big beat.
Causes of ectopic beat are the following
  • Overindulgence of tea,coffee, cigarettes, alcohol, anxiety. 
  • Dyspepsia
  • Digitalis overdosage
  • Rheumatic fever
  • Ischaemic
  • Hypertensive
  • Thyrotoxic and cardiomyopalhic heart diseases 
What are the synonym of ectopic beat: 
Ectopic beat is also known as premature beat, extrasystoles.
How can you modify ectopics in a patient?
Ectopics can be abolished by vagotonic procedures, and increased by vagolytic procedures
If the ectopic pace-maker is situated in the atrium ,resulting in paroxysmal atrial tachycardia vagotonic procedures can terminate it. Vagotonic procedures have no effect on ventricular tachycardia.
What are the Vagotonic procedures? 
Mechanical measures like carotid sinus massage (put your right thumb on the right side at the level of the upper border of thyroid cartilage in the neck and then on the left side  massage for 3-5 seconds at a time). Before the procedure always examine for both carotid pulse and auscultate for carotid bruit.
The other procedures are self-induced gagging or vomiting, pressure over the eyeballs.
Valsalva manoeuvre, stretching the arms and body.
Drug like digitalis.
Coughing as well as breath holding, head lowering between the knees.
What are the Vagolytic procedures : Exercise
Drugs like atropine and amyl nitrite.
How will you differentiate  between multiple ectopics and atrial fibrillation ?
Both these conditions present as irregularly irregular pulse. Sothey have to be differentiated from one another
1.First count the pulse rate. If this is > 100 per minute, it is AF but if the pulse rale is < 100 per
minute. It can be multiple ectopics or digitalised AF (treated case of Af).
2.The ectopic beat is a small one and occurs prematurely. So you may get the typical phenomenon
of small pause followed by small beat, big pause (compensatory pause) followed by big beat. If this typical cadence is felt, this is definitely ectopic and it is not a case of atrial fibrillation.
3.Calculate the pulse deficit. If it is > 10, it is AF. It the pulse deficit is < 10. But this can be again multiple ectopics or digitalised AF. To diiferentiate between these two following measures are adopted.
The patient is allowed to do mild exercise (if the condition permits). He will sit and touch the toes
with his fingers, and will lie down again. This is done for 5-6 times successively. The heart of AF becomes more irregular after exercise. If the pulse deficit is more than 10 after exercise ,it is a case of digitalised AF and if the pulse deficit remains same (below 10) or diminished after exercise , the diagnosis of multiple ectopics becomes obvious.
The patient is examined for
a) JVP-a-wave is absent in AF : a-wave is present in multiple ectopics.
b) S1-Varying intensity of S1 is heard  in AF: no change in multiple ectopics.
c) Auscultation of the apex-If MS is the cause of AF, presystolie component of the diastolic murmur will disappear but no change of murmur is heard  in multiple ectopics.
d)ECG-P' waves will be replaced by T waves in AF; ectopics are easily diagnosed by ECG.
What are the causes of irregular rhythm with normal heart rate :
1) Multiple extrasystoles.
2) Digitalised AF.
3) Sinus arrhythmia.