Exam 2 Arrhythmias Flashcards
(183 cards)
Which ventricle has a larger muscle mass and why?
Left ventricle
-has to squeeze blood out against higher pressure
What does the P wave represent?
Atrial depolarization
*not atrial contraction, immediately followed by it
What is the PR interval a measure of?
AV nodal conduction time
What drugs slow AV node conduction and can lengthen the PR interval?
Beta blockers
CCB (diltiazem, verapamil)
What does the QT interval represent?
Ventricular repolarization
What does the early part of the QRS wave represent?
Ventricular depolarization
What is an electrocardiogram?
Non-invasive representation of electrical activity of the heart
*12 lead often used
*3 lead good enough to diagnose arrythmias
How can we determine heart rate by looking at an ECG?
Multiple the number of R waves present by 10
(if 8 present, x10=80bpm)
What are the 4 questions to ask to determine if a rhythm is normal?
- Is there a P wave in front of every QRS complex?
- Is there a QRS complex after every P wave?
- Is the rhythm regular (interval between R waves all the same)?
- What is the heart rate (too slow/fast)?
What is QTc?
The corrected QT interval for heart rate
If the PR interval is longer than what it is too long?
0.2 seconds
(if P wave falls in one box and R wave is greater than a box away it is too long!)
What causes lengthening of the QRS interval?
Sodium blocking
Drugs that make what change to the ECG are the most concerning?
Lengthen the QT interval
AT what lengthening of the QT interval do we start to get concerned?
0.5 seconds or greater
(> or = 500 ms)
*increases Torsades de Pointes risk
When the QTc interval is > or = 500 ms, what does this increase the risk of?
Torsades de Pointes
What is a big risk with development of Torsades de Pointes?
Sudden cardiac death
What are the risk factors for developing Torsades de Pointes?
65 or older
Electrolyte imbalance (hypokalemia)
Heart failure
What are the 5 Supraventricular Arrhythmias?
(occur above the ventricles)
-Sinus Bradycardia
-Atrioventricular (AV) Block
-Sinus Tachycardia
-Atrial Fibrillation
-Supraventricular Tachycardia
What are the 3 Ventricular Arrhythmias?
-Premature Ventricular Complexes (PVCs)
-Ventricular Tachycardia
-Ventricular Fibrillation
What is considered “tachycardia”?
HR => 100
What is considered “bradycardia”?
HR => 60
What is sinus bradycardia?
HR < 60 BPM
Impulses originate in SA node
*Note: everything on ECG is normal, just too slow (Not enough R waves)
What is a common cause of sinus bradycardia?
Drug-induced
What is the mechanism behind sinus bradycardia?
Decreased automaticity of SA node
*depolarizes too slowly