Cardiology Flashcards
BPM for the atrial cells
55-60 bpm
BPM for the AV node
45-50 bpm
BPM for bundle of his
40-45 bpm
BPM bundle branch
40-45 bpm
BPM for purkinjie cells
35-40 bpm
BPM for myocardial cells
30-35 bpm
Main function of the SA node aka the pacemaker
The pacemaker dictates the rate at which the heart will cycle through its pumping action to circulate blood. The pacemaker creates an organized beating of all cardiac cells in a specialized sequence to produce effective pumping action
Where is the SA node located and where does it receive its blood supply?
Its located in the wall of the right atrium and mainly comes from the RCA. In 38% of cases it can come from the LCA and in less cases can come from both arteries.
P.11 arrhythmia recognition
Where are the internodal pathways located and what are its function?
They are located in the walls of the right atrium and inter-atrial septum. Their main purposes is to conduct the impulses from the SA node to the AV node.
Where is the AV node located and what is its main purpose?
The AV node is located in the wall of the right atrium next to the opening of the coronary sinus. It slows down the signal from the SA node long enough for the atria to overfill and contract.
Note: The AV node is always supplied by the RCA.
Where is the bundle of his located and how does it function?
It starts after the AV node and travels the walls of the right atrium and inter ventricular septum. It allows for the singalong from the AV node travel down the heart.
NOTE: The bundle of his is the only route of communication between the atria and the ventricles.
Where is the LBB located and how does it function?
It begins at the end of the His bundle and travels through the inter-ventricular septum. The LBB sparks the fibers that will set off the left ventricle and left face of the left ventricular septum. It ends at the beginning of the left anterior fascicles.
Where is the RBB located and how does it work?
The RBB starts after the Bundle of His and sparks the right ventricle and right face of the inter-ventricular septum. It terminates in the purkinjie fibers associated with it.
Explain the Left and Right Fascicles
Both fascicles travel to the left ventricle. The left supplies the anterior part of the heart while the right supplies the posterior.
The LAF Innervates the anterior and superior aspects of the left ventricle. It is a single stranded in comparison to the right which branches off into smaller pathways
The RPF innervates the posterior and inferior side of the left ventricle. It is harder to block this fascicles as it is so widely distributed rather than being one main strand like the LAF.
Explain the Purkinje system
They are made up of individual cells just beneath the endocardium. They are cells that directly innervate the myocardial cells and initiate ventricular depolarization cycle.
List the four arrthymogenic zones
Sinus
Atria
Nodal / Bundle
Ventricles
List the sinus arrhythmias
Sinus Bradycardia NSR Sinus Tachycardia SA block SA pause/arrest Sinus arrhythmia/PAC
List Atria arrhythmias
Ectopic atrial Atrial Flutter Atrial Tachycardia A-fib WAP - wandering atrial packe maker Multifocal atrial Tachycardia Variable atrial flutter
List Nodal arrhythmias
Junctional Junctional Escape 1st Degree Block Accelerated Junctional Junctional Tachycardia AV nodal re-entry PJC 2nd Degree block 3rd Degree Block
List Ventricular arrhythmias
Ventricular Escape Idoventricular Accelerated idioventricular PVC Asystole Ventricular Tachycardia Torsades de Pointers Polymorphic V-tach V-fib
List each phases of depolarization and repolarization
Cells are naturally negatively charged. Eventually the cell becomes so positive that a new set of channels opens. The point at which the channels open is called the threshold potential and the channels are fast sodium channels. This process is the balance of the Sodium Potassium pump that allows the heart to contract.
Phase 0 - A influx of sodium makes the cell become positively charged. This creates a spike in the cell and allows for the cell next to it to do the same
Phase 1 - When the cell is at its peak positive charge some negative ions of chloride enter the cell to slow down the sodium. This allows for two more channels to open. One for the slow sodium and one for calcium
Phase 2 - The cells begins to plateau. These two cells combined allow for the cell to maintain a steady positive/depolarized state. Calcium is a double positive ion.
Phase 3 - Some potassium channels open and allow it to go into the cell to re polarize. The positive cells now leave the cell.
Chronotropic
Speeds up rate
Inotropic
Increases contractility
Dromotropic
Speeds up conduction through the AV node
Main chemical messenger for the Parasympathetic System
Acetylcholine
Main chemical messenger for the sympathetic system
Epinephrine
What is the main pathway from the Central Nervous System to the heart?
Vagus Nerve (10th cranial nerve)
How does epinephrine work on the sympathetic nervous system?
It shortens the phase 4 of the action potential essentially speeding up the pacemaker action of the SA node and all the other pace makers as well
How does acetylcholine affect the parasympathetic nervous system?
It slows the rate of depolarization essentially making the cells less excitable.
BPM for the SA node
60-100 bpm
P wave represents…
Atrial depolarization
Duration of P wave
.08 - .11
TP Wave represents….
Represents the repolarization of the atria
Normal Duration: usually not seen
Wave Orientation: Opposite to the P wave
