Weel 10: Cardiovascular Sys P2 (ECG) Flashcards
What is an ECG?
A picture of the electrical conduction of the heart
The normal pacemaker of the heart is the?
SA node
The P wave represents what? This sets the heart to beat at what rate?
The SA nodes, also known as the pacemaker
- Sets heart to beat at rate of 60-100BPM
The end of the P wave (straight line ish) represents what? This sets the heart to beat at what rate?
The AV node “resistor node” as it slows down the electrical impulse b/w atria and ventricles
- Sets rate of 40-60 BPM
- Creates flat baseline after P wave
Purkinje Fibers sets heart rate at what?
20-40BPM
The QRS complex represents what?
Ventricular depolarization which cause ventricular contraction
The T wave represents what?
Ventricular Relaxation and Repolarization
The T wave represents what?
Ventricular Relaxation and Repolarization
Describe the steps of the heart contracting in relation to the ECG wave and the SA/AV nodes
- Atrial depolarization occurs initiated by the SA node: causing the P wave
- With atrial depolarization complete, the impulse is delayed at the AV node: causing the “flatline” right before the Q
- Ventricular depolarization begins at the apex, causing heart contraction and the QRS complex, and then atrial repolarization occurs
- Ventricular depolarization is complete: “Flatline” right before T
- Ventricular repolarization begins at apex, causing T wave
- Ventricular repolarization is complete: end of T wave
What are the 5 Leads on the ECG?
RA placement: White (Right)
LA placement: Black (Left)
RL placement: Green (middle to right)
LL placement: Red (Left)
V placement: Green (Right)
Why is a five lead better than a 12 lead? If there is concern should you switch to a 12 lead?
A 5 lead provides lot’s of information, and when put on torso allows for better reading then on limbs (where coldness and other things may interfere with the readings)
- But if something is concering a 12-lead ECG is ordered to provide more information
Limb vs. precordial leads?
Limb leads are placed on arms and legs of the individual
Precordial are placed on torso (precordium)
What are the six limb leads called?
Lead I, II, III, aVL, aVR, AVF
- letter A stands for augmented as these leads are calculated as a combination of leads I, II, and III
What are the six precordial leads called?
Leads V1, V2, V3, V4, V5, V6
How many seconds should the PR interval be?
Between 0.12-0.20
How many seconds should the QRS interval be?
0.08-0.1 seconds
How long should the QT interval be?
Less than 0.44 seconds
A depressed ST segment may indicate what?
Myocardial ischemia or digoxin toxicity
An ST segment elevation may indicate what?
Myocardial injury
How do you make sure an ECG’s rate and rhythm is regilar?
Make sure space between each r wave is equal (count the boxes)
Arrythmias are defined by what?
The speed of the heartbeats: slow and fast, or bradycardia and tachycardia
Bradycardia can be defined as what in relation to ECG / conduction
Malfunction of SA node (sick sinus syndrome), slowing down of the electrical signal to the ventricles (heart block)
Bradycardia can be defined as what in relation to ECG / conduction
Malfunction of SA node (sick sinus syndrome), slowing down of the electrical signal to the ventricles (heart block)
Tachycardia above the ventricle causes what?
an extra or early electrical impulse travels around and around the atria causing the atria to “flutter” ( atrial flutter); electrical activity in atria is disorganized and rapid causing very rapid contractions of the atria (A fib)
What are symptoms of bradycardia?
Hypotension
Pale, cool skin
Weakness
Angina
Dizziness or syncope
Confusion or disorientation
SOB
What are treatments for bradycardia?
Atropine
Pacemaker may also be required
Bradycardia can occur in response to?
Carotid sinus massage
Valsalva’s manoeuvre
Hypothermia
Increased intraocular pressure
Increased vagal tone
Administration of parasympathomimetic drugs
Bradycardia can occur in what disease states?
Hypothyroidism
Increased intracranial pressure
Obstructive jaundice
Inferior wall MI
What can tachycardia be associated with/
Exercise
Fever, Pain
Hypotension
Hypovolemia
Anemia
Hypoxia
Hypoglycemia
MI
Heart failure
Hyperthyroidism
PE
Anxiety, fear
What are treatments for tachycardia?
Adrenergic blockers to reduce HR and myocardial oxygen consumption
Antipyretics to treat fever
Analgesics to treat pain
If an ECG is sawtooth-shaped flutter waves what condition is it indicating?
Atrial flutter
- Atrial tachydysrhythmias
Atrial flutter usually occurs with?
CAD
Hypertension
Mitral valve disorders
Pulmonary embolus
Chronic lung disease
Cor pulmonale
Cardiomyopathy
Hyperthyroidism
Drugs: digoxin, quinidine, epinephrine
High ventricular rates (>100) and loss of the atrial “kick” can decrease CO and precipitate HF, angina
Risk for stroke due to risk of thrombus formation in the atria
What is the primary goal for treatment of atrial flutter?
Slow ventricular reponse by increasing AV block
Drugs to slow HR: calcium channel blockers, -adrenergic blockers
Electrical cardioversion may be used to convert the atrial flutter to sinus rhythm emergently and electively.
Antidysrhythmic drugs (e.g., amiodarone, propafenone) to convert atrial flutter to sinus rhythm or to maintain sinus rhythm
Radiofrequency catheter ablation can be curative therapy for atrial flutter.
