EKG Flashcards
(30 cards)
What are the two primary methods for determining heart rate on an EKG strip?
Count the number of QRS complexes in a 10-second strip and multiply by 6, or use the ‘300, 150, 100, 75, 60, 50’ rule by dividing 300 by the number of large boxes between R waves.
How do you confirm sinus rhythm on an EKG?
There should be a P wave before every QRS complex, a QRS complex after every P wave, and P waves should be upright in leads I and II.
Which leads are best for identifying P waves?
Leads II and V1 are the best leads for identifying P waves.
What is the normal PR interval, and what does a prolonged PR interval suggest?
The normal PR interval is 0.12-0.2 seconds (3-5 small boxes). A prolonged PR interval suggests first-degree AV block or other conduction delays.
A patient presents with palpitations, and their EKG shows no discernible P waves with an irregularly irregular rhythm. What is the most likely diagnosis?
Atrial fibrillation.
How does ventricular tachycardia differ from supraventricular tachycardia in terms of QRS duration?
Ventricular tachycardia has a wide QRS complex (>0.12 sec), whereas supraventricular tachycardia has a narrow QRS complex (<0.12 sec).
What are the criteria for diagnosing STEMI based on ST-segment elevation?
ST elevation ≥1 mm in two contiguous limb leads or ≥2 mm in two contiguous precordial leads, or new left bundle branch block (LBBB) in the setting of acute chest pain.
Which leads correspond to the inferior wall of the heart, and what vessel is commonly implicated in an infarction in this area?
Leads II, III, and aVF correspond to the inferior wall, and the right coronary artery (RCA) is commonly implicated.
What EKG changes are associated with hyperkalemia?
Peaked T waves, widened QRS complex, prolonged PR interval, and eventual sine-wave pattern in severe cases.
A patient’s EKG shows progressively lengthening PR intervals followed by a dropped QRS complex. What is the likely diagnosis?
Second-degree AV block Type 1 (Wenckebach).
How does second-degree AV block Type 2 differ from Type 1 on an EKG?
In Type 2, the PR interval is constant before dropped QRS complexes, whereas in Type 1, the PR interval progressively lengthens before a dropped QRS.
What is the defining characteristic of third-degree (complete) heart block?
P waves and QRS complexes are present but have no relationship with each other (atrial and ventricular dissociation).
What are the EKG findings in Wolff-Parkinson-White syndrome?
Shortened PR interval (<0.12 sec), slurred upstroke of QRS (delta wave), and wide QRS complex (>0.12 sec).
What is the significance of ‘hyperacute T waves,’ and in what clinical scenario are they most concerning?
They are early signs of myocardial infarction and suggest acute coronary occlusion before ST-segment elevation occurs.
How can you differentiate between left and right bundle branch blocks on an EKG?
Right bundle branch block (RBBB) shows an rsR’ (bunny ears) in V1 and wide S waves in V6, while left bundle branch block (LBBB) shows a wide, negative QRS in V1 and tall, broad R waves in V6.
What is the typical EKG pattern of atrial flutter?
A ‘sawtooth’ pattern of flutter waves, typically in leads II, III, and aVF, with a regular atrial rate of ~250-350 bpm.
What is the significance of ST-segment depression, and how does it differ from ST-segment elevation in terms of pathology?
ST depression suggests ischemia or NSTEMI, while ST elevation indicates acute infarction or STEMI.
How does the QRS complex change in a patient with left ventricular hypertrophy?
The QRS complex becomes larger, with deep S waves in V1 and tall R waves in V5/V6 (Sokolow-Lyon criteria).
What EKG finding is considered a hallmark of Brugada syndrome?
ST elevation with a coved or saddleback appearance in leads V1-V3.
Which type of heart block is most likely to require a pacemaker?
Second-degree AV block Type 2 and third-degree (complete) heart block.
A patient has diffuse ST-segment elevations in multiple leads without reciprocal changes. What is the most likely diagnosis?
Pericarditis.
What are the distinguishing features of ventricular fibrillation compared to ventricular tachycardia?
Ventricular fibrillation is chaotic, irregular, and has no organized QRS complexes, while ventricular tachycardia has regular, wide QRS complexes.
In which leads would you expect to see reciprocal changes in a patient with an inferior STEMI?
Leads I and aVL.
What arrhythmia is characterized by an ‘irregularly irregular’ rhythm with no P waves?
Atrial fibrillation.
