1. Cardiology Flashcards
Explane phase Zero of the cardiac action potential
Fast sodium channels open and a rapid influx of Na enters the cell causing the cell to become less negative.
This is known as the upstroke
Explane phase one of the cardiac action potential cycle
Fast sodium channel gates close reducing the amount of Na+ that can enter. Cl- - enters the cell while K+ leaves makeing the cell more negatvie.
Explain phase Two of the cardiac action potential cycle
Both sodium and potassium enter and leave the cell at the same rate leaving the rate leaving the cell at the same electrical charge.
This is known as the plateau stage.
Explane phase three of the cardiac action potential cycle
Potassium rapidly leaves the cell leading to the cell becoming more negativly charged and bringing the cell down to its resting membrane potential
Explain phase four of the cardiac action potential cycle
Normal movements of ions into and out of the cell leaving the fell at its resting potential.
What are the Waves and complexes of an ECG
P Wave
PR interval
QRS complex
ST segment
J point
T wave
Whats the normal duration of the PRI
0.12-0.2 seconds
Normal duration of a QRS Complex
0.06-0.12 seconds
Whats the 5 Step ECG method
- Rate
- Regularity
- P wave
- PR Interval
- QRS Complex
What is the NSW Ambulance protocol for narrow complex tachycardias
- Pt symptomatic with SVT (narrow complex) ➡️ YES
- Pt LOC = A or V ➡️ Yes
If yes valsalva manoeuvre repeat once if not successful then transport. - Pt LOC =A or V ➡️ No
Synchronised cardioversion
1st shock 100j
2nd shock 150j
3rd shock 200j
Reassess after each shock (rapid ABC)
What are the three contrindications for syncronised cardioversion
1- pt LOC is A or V
2- pt less than 1
3- pt indicating sinus tachycardia, Rapid AF, Atrial Flutter
What does Paroxysmal mean?
Abrupt onset and abrupt termination
What heart rate is the difference for SVT and Sinus tachycardia?
Less than 150bpm equals sinus tach
Greater than 150bmp equals SVT
Mechanism of action for Adenosine?
Stimulates A1 adenosine recpeter and opens ACh senstive K+ channels. By inhibiting Ca+ channels leads to a slower conduction through the Atrioventricular node.
Victoran protocol for adenosine
Eg indications, dose, contraindications
6mg:2ml
Indications- SVT
Dose- 6mg IV
12mg IV if no reversion after two minutes
12mg IV if no reversion after two minutes
Contraindications-
AF,
Atrial Flutter
Ventricular rhythms
2nd or 3rd AV block
Describe the workings of the Valsalva maneuver
Pushing on a closed glottis increases intrathoracic pressure, opening of the airway decreases intrthoracic pressure now an increase in venous return increaces transmural pressure (pressure within the right atria) stretches the aorta stimulating baroreceptors activating a reflex vagus nerve stimulation leading to a reflex bradycardia.
Whats the following rhythm
SVT
Whats The Following rhythm
SVT
Definitions of Wide Complex Tachycardias
- No Atrial association
- Ventricular rate greater than 100
- QRS Greather than 0.12seconds (wide or broad)
NSW Ambulance protocol for wide complex tachycardias
- Sypmtomatic and VT confirmed ➡️ Yes
- Pt LOC = A or V
If YES
administer amiodarone and urgant transport
If NO
Synchronised cardioversion same as SVT
Amiodarone protocol for NSW Ambulance
Presentations
indications
contraindications
dose
150mg:3ml
Indications- cardiac arrest and wide complex tachycardia
Contraindications- torsades de Pointes
Dose-
Cardiac arrest-
300mg repeat 150mg once 450mg max dose
Tachycardia-
50mg Every 3 mins. Max dose 300mg
Whats the following P wave indicate and why
Right atrial Enlargement
In right atrial enlargement, right atrial depolarisation lasts longer than normal and its waveform extends to the end of left atrial depolarisation
Whats the following p wave indicate and why
Left atrial enlargement
In left atrial enlargement, left atrial depolarisation lasts longer than normal but its amplitude remains unchanged
A notch (broken line) near its peak may or may not be present
What are the requirements for pathalogical Q waves (4points)
- > 0.4 seconds wide
- > 2mm deep
- > 25% depth of QRS Complex
- Seen in leads v1- v3
What do pathological Q waves indicate
Current or prior Myocardial Infarction
What arteries are effected if an inferior MI is suspected
Right Coronary Artery (RCA)
What artery is effected in a septal MI?
Left Anterior descending (LAD)
What artery is effected in an Anterior MI?
Left Anterior descending LAD
What artery is effected in a lateral MI?
Circumflex artery / LAD
Inferobasal Mi is effected by what artery’s
RCA
How to diagnose a posterior MI?
Depression in V1-2 and possibly v3
Confirm with v7,8,9
ACS management
Hx and vitals
Supplement O2 if required (cynotic or decrease SPO2
IV access
Quick ECG confirm STEMI
Admin Asprin unless contraindicated (300mg)
GTN unless contraindicated (600mcg)
Morphine (2.5-5mg)
Five STEMI imposters
- Left Ventricular hypertrophy
- LBBB
- Ventricular rhythms
- BER
- Pericarditis
Left ventricular hypertrophic signs
Increase QRS amplitude
ST depression and asymmetric T wave inversion
Dragged out ST segmant
STRAIN PATTERN
QRS amplitude steps
1- v1 S wave count depth in mm from baseline to negative point
2- tallest R wave in v5-6 count height in mm
3- add the two figures greater than 35mm suspect LVH
Cardiac arrest NSW Drug protocols
- Adrenaline 1mg:10mL every four minutes
- Amidarone 300mg then 150mg max of 450mg cycle between adrenaline
- Lignocaine 100mg repeat once max dose 200mg cycle between adrenaline
Post ROSC care
Rapid ABCs
Titrate O2 95% 99%
Etco2 35-45
Normalise BP 100mmhg
Normalise temp
Normalise BGL
12 lead
Symptomatic BradyCardia management
Symptomatic ➡️ Yes
Oxygen if poorley perfused
Vitals, 12Lead
IV
Atropine
If unsuccessful adrenaline infusion. If unresponsive to Adrenaline TCP
Asymptomatic bradycardia management
Monitor vital
12 lead
Transport to ED
Second degree type 1 is
PRI gradually lengthen till drops a complex
Second degree type 2 block is
Randomly drops a QRS complex
Third degree heart block is
No av association
What is concordance
St segmant and T waves deflect in the same direction.
Do BBB have concordance or discordant?
Normally BBB produce discordants
Sgarbrossa Criteria is?
1- concordant ST segmant elevation greater than 1mm in any lead
2- concordant ST segment depression greater than 1mm in lead V1- V3
3- Discordant ST/S ratio greater than 0.25
