Sarma-Bradyarrhythmias

Front 1

conductivity in cardiac tissues

Back 1

purkinje fibers-fastest rate
AV node-slowest rate

Front 2

Location: in wall of right atrium close to SVC
Function: Main pacemaker
Inherent rate: 60-00 bpm; can go higher during exercise.
Blood supply:
Right coronary artery (most common; 55-60%)
Left coronary artery (less common 40-45%)
Nerve supply: Sympathetic & Parasympathetic

Back 2

SA node

Front 3

Location: wall of right atrium, close to coronary sinus.
Function: slowest conduction velocity; this allows atrial contraction to occur.
Inherent pacing rate:40–60bpm
Blood supply:
AV nodal artery and first septal perforators of the left anterior descending coronary artery

Back 3

AV node

Front 4

Administer 0.2 mg/kg of propranolol + 0.04 mg/kg of
Atropine and check HR.
Propranolol blocks sympathetic and atropine blocks the
Parasympathetic system.
Thus after total autonomic block the normal intrinsic HR (IHR) is around 117.2 – (0.53 x Age)
Older the patient lower is the IHR.
If IHR is low for the given age of that patient it indicates SA node disease.

Back 4

normal intrinsic heart rate

Front 5

conductivity in cardiac tissues

Back 5

purkinje fibers-fastest rate
AV node-slowest rate

Front 6

heart rate slow
normal rhythm
normal p wave and QRS morphology

Back 6

sinus bradycardia

Front 7

consistent prolonged PR interval, normal QRS

Back 7

primary AV block

Front 8

increasing PR interval, eventually leading to a dropped QRS comples
cycle repeats

Back 8

Mobitz type 1 secondary AV block (Wenckebach)

Front 9

Where is the defect in Mobitz type 1?

Back 9

above bundle of His

Front 10

consistent PR interval, intermittent dropped QRS complexes

Back 10

Mobitz type 2 secondary AV block

Front 11

Where is the defect in Mobitz type 2?

Back 11

below bundle of His

Front 12

The sinus is fairly regular and the rate may be normal.
The PR interval gets progressively prolonged until
the impulse is no longer conducted to the AV node.
R-R interval is progressively shorter. (Grouping)
The delay is with in the AV node, or the internodal
Pathways, and it is above the His bundle.
The PR interval is shortest after the dropped P wave due
to some recovery of the conduction system.
This type of block is commonly seen with inferior MI and
may resolve spontaneously.

Back 12

mechanism of mobitz type 1

Front 13

P waves are regular usually at normal rate.
P-R interval is fairly constant.
Some P waves are not conducted to the ventricle.
Failure to get to the ventricle is unpredictable.
Due to this dropped P waves there is grouping of
the QRS. This is a clue to possible block.
The conduction defect is usually below the His
bundle.

Back 13

EKG features of mobitz type 2 (more serious than mobitz type 1)

Front 14

The sinus depolarizes the atria normally.
The impulse is not conducted to the ventricles.
Another pacemaker site will start the impulses to continue
ventricular depolarization. (Regular at a slower rate)
The AV node (or AV junction), the bundle branches or the
purkinje fibers may cause ventricular depolarization.
QRS morphology depends on the site of the secondary
Pacemaker; QRS is narrow if it is from the AV junction or
wide if it is from the lower pacemaker sites.
Complete heart block may occur as a congenital
abnormality.

Back 14

Complete AV block (3rd degree block)

Front 15

Caused by fibrosis or other disease of the sinus node.
Presence of slow and fast rhythms with long pauses
makes the EKG diagnosis.
If the patients are symptomatic with syncope, dizziness
or other hemodynamic problems a pacemaker is
recommended to take care of the bradycardia.
Drug therapy may be needed for the fast arrhythmias.
Newer pacemakers can also treat the tachycardias by
over drive suppression. (Antitachycardia pacemakers)

Back 15

Sick sinus syndrome (Tachy-brady syndrome)

Front 16

pacemaker classification system

Back 16

Class I-procedure is definitely recommended
Class IIa-benefits outweigh the risk
Class IIb-barely indicated
Class III-not recommended

Front 17

3rd degree, advanced 2nd degree:
with symptoms
drug-related
Escape rate < 40bpm or any rate below AV node
>3 sec pause
>5 sec pause and AF
AV junction ablation/surgery
neuromuscular diseases
exercise related (not ischemic)
2nd type II:
with wide QRS (RBBB incl.)
3rd:
with cardiomegaly or LV dysfunction
below the AV node

Back 17

Class I pacemaker recommendation

Front 18

3rd persistent
2nd (intra- or infra-His) found during EPS
1st and 2nd with symptoms (PM-syndrome-like or hemodynamic)
2nd type II with narrow QRS

Back 18

Class IIa pacemaker recommendation

Front 19

Any AVB + neuromuscular disease
Any AVB due to drug use, expected to recur after drug withdrawal

Back 19

Class IIb pacemaker recommendation

Front 20

1st asymptomatic
2nd supra-His type I asymptomatic
any transient

Back 20

Class III pacemaker recommendation (not recommended)