Cardiac Arrhythmia Flashcards
What does PR interval indicate?
Measures Conduction time from atrium to ventricle
What does QRS wave represent
The time it takes for all ventricular cells to be excited..
I.e intraventricular conduction time
The electrical activities of the heart control…….. of the heart
Rhythm
The mechanical activities control the …….. of the heart
Pumping action of the heart
When the mechanical and electrical part of the heart fails respectively it is called
Heart failure
Arrhythmia
What is the pathophysiology of Arrhythmia?
There’s a change in the membrane potential of cardiac cells which affect the rhythm…
Anti Arrhythmia drugs functions by Modulating the actions of ion channels on the membrane
What forms the electrical conducting system of the heart
The pacemaker cells
The pacemaker cells include
Bundle of His
Purkinje fibre
SA node
AV node
What is the native pacemaker of the cell
SA node is the intrinsic pacemaker of the cell.
It has the highest intrinsic firing rate 60-100times/min
The intrinsic firing activity of the other pacemaker cells are
AV node and bundle of His 50-60/min
Purkinje fibre 30-40/min
The other pacemakers overriden by SA node is called
Latent pacemaker
Explain override suppression
This occurs when the SA node suppresses the intrinsic firing activity of the pacemaker cells and entrains them to fire at the SA nodal firing activity
The two major mechanism in the pathophysiology of cardiac Arrhythmia
Change in automaticity
Changes in conductivity
What does the PR interval represent
The time it takes for conduction to spread from the the atrium to the ventricles
What does the QRS complex represent
Intraventricular depolarization.
What is the QT interval
The time it takes for ventricular action potential
ST segment represents
Plateau phase
The intrinsic rate of firing of the SA node is
60-100 beats per minute
The intrinsic firing activity of the AV node and bundle of His is ……
50-60 beats per min
The intrinsic firing activity of the Purkinje fibre is
30-40 beats per min
What is the nernst potential?
The difference between an ions nernst potential and the cell membranes potential
What results in early after-depolarization
This occurs when there is incomplete inactivation of Na + channel or decrease repolarizing potential of k+
Example of early after depolarization is seem in…… and it results in ………
Congenital QT syndrome results in torsades de pointes
What results in delayed after-depolarization
When Na+/K+ is shallow
Ca+ conc is high
B adrenergic stimulation
Digitalis glycoside toxicity
Delayed after-depolarization results in tachycardia and extra stole if it results in ………….
Another DAD
