Improper formation of sinoatrial impulse and its propagation through the junctional issues of the heart is cause
the situation called Heart Block fact any defect in the conducting system of the heart isknown as Heart block Classification
1. SA block.
2. AV block
3. Bundle branch block.
4. Arborisation or Purkinjee block.



it is due to excessive vagal tone from different neurohumoral factors. Ischaemia, fibrosis or calcification of SA node and rugs, e.g. Ca-channel blockers, Digitalis, Antiarrhythmic drugs or Sympatholytic drugs are also respon impulse is generated in the SA node, heart as a whole will sible. As no miss a beat. Therefore, there is dropped bease and
during this period no heart sounds are audible and no pulsation in jugular vein is seen. ECG is diagnostic which shows
complete absence of all complexes provided no escape beatsoccur and the P-P interval is usually multiple of previous P
P interval. This is also known as Mobitz type II SA block Sometimes there is progressive shortening of sinus P-P interval
before the long pause. This is called Sinoatrial Wenckebach or Mobitz p A block. In Mobitz type II SA block, sinus leading toabsence of P waves of sinus origin. SA block should beimpulse transmission is blocked at the SA junction
differentiated from sinoatrial arrest or sinus pause where P-P interval is simply prolonged. SA block is actually included
under sick sinus syndrome (SSS).Treatment In many cases no treatment is necessary. The offending drug
(usually Digitalis) if in use should be withdrawn. Atropine sulphate 0.6 mg four times daily or Ephedrine sulphate 25 mg