Supraventricular Tachycardia: Causes and Characteristics

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What is the primary reason why the P waves are often difficult to discern in supraventricular tachycardia?

The SA node is not functioning properly

The pacemaker site is often located near the AV node

The use of sympathomimetic medications affects the P wave

The rapid heart rate makes the P waves indiscernible (correct)

Which of the following conditions is NOT a common cause of supraventricular tachycardia?

Hypokalemia (correct)

Hypoxia

Digitalis toxicity

Ischemic heart disease

What is the typical heart rate range for supraventricular tachycardia?

250-300 per minute

300-350 per minute

100-150 per minute

150-250 per minute (correct)

What is the effect of rapid rates on cardiac output in patients with supraventricular tachycardia?

Marked reduction in cardiac output Signup and view all the answers

What is the typical PR interval for ectopic pacemakers located near the SA node?

Close to 0.12 second Signup and view all the answers

What is the typical effect of supraventricular tachycardia on patients with good cardiac reserves?

Patients with good cardiac reserves can tolerate SVT well for short periods Signup and view all the answers

What is the effect of reduced diastolic phase on coronary artery perfusion?

It compromises coronary artery perfusion Signup and view all the answers

What is the atrial rate in atrial flutter?

250-350 per minute Signup and view all the answers

What is the characteristic appearance of P waves in atrial flutter?

Both sawtooth and picket fence pattern Signup and view all the answers

What is the treatment of choice for atrial flutter with a ventricular rate of 150 beats per minute?

Electrical therapy with synchronized cardioversion Signup and view all the answers

What is the effect of atrial fibrillation on cardiac output?

It decreases cardiac output by 20-25% Signup and view all the answers

What is the characteristic rhythm of atrial fibrillation?

Irregularly irregular Signup and view all the answers

What is the most common sustained cardiac arrhythmia?

Atrial fibrillation Signup and view all the answers

What is the cause of atrial dilation in atrial fibrillation?

All of the above Signup and view all the answers

What is the classification of atrial fibrillation that continues for more than a year despite medical treatment?

Permanent Signup and view all the answers

What is the effect of rapid ventricular rates in atrial fibrillation?

It compromises cardiac output Signup and view all the answers

What is the potential consequence of a ventricular rate of less than 60 in patients with atrial fibrillation?

Cardiac output decrease Signup and view all the answers

Which of the following is a characteristic of atrial fibrillation with a rapid ventricular response?

Loss of atrial kick and rapid ventricular response Signup and view all the answers

What is the recommended treatment for a stable patient with atrial fibrillation?

Obtaining a 12-lead ECG and establishing IV access Signup and view all the answers

What is the function of the AV junction in the conductive system?

To slow the impulse between the atria and the ventricles Signup and view all the answers

What is the name of the part of the AV node that penetrates the fibrous tissue that separates the atria from the ventricles?

Lower portion of the AV node Signup and view all the answers

What is the cause of AV blocks?

All of the above Signup and view all the answers

What is the classification of AV blocks based on the degree of the block?

First-degree, second-degree, and third-degree Signup and view all the answers

What is the characteristic of a first-degree AV block?

A delay in conduction at the level of the AV node Signup and view all the answers

What is the PR interval in a first-degree AV block?

More than 0.20 second Signup and view all the answers

What is the underlying rhythm in a first-degree AV block?

Sinus bradycardia Signup and view all the answers

What is the typical ventricular rate in a 2:1 AV block?

Usually bradycardic Signup and view all the answers

What is the typical P wave pattern in a 2:1 AV block?

Two P waves for each QRS complex Signup and view all the answers

What is the typical treatment for a 2:1 AV block?

Prepare for transcutaneous pacing only if signs of poor perfusion are present Signup and view all the answers

What is the typical etiology of a 2:1 AV block?

Usually associated with acute MI and septal necrosis Signup and view all the answers

What is the typical QRS complex morphology in a 2:1 AV block?

Can be normal or abnormal Signup and view all the answers

What is the typical atrial rate in a 2:1 AV block?

Unaffected Signup and view all the answers

What is the typical clinical significance of a 2:1 AV block?

Can compromise cardiac output, causing problems such as syncope and angina Signup and view all the answers

What is the typical outcome of a 2:1 AV block?

Can develop into full AV block Signup and view all the answers

What is the typical etiology of a third-degree AV block?

Usually associated with AMI, digitalis toxicity, or degeneration of the conductive system Signup and view all the answers

What is the typical ventricular rate in a third-degree AV block?

Can be less than 40, between 40-60, or more than 60 Signup and view all the answers

What is the usual consequence of a first-degree AV block?

It often leads to a more significant block Signup and view all the answers

Which type of block is often a transient phenomenon that occurs immediately after an inferior wall MI?

Second-degree Mobitz I Signup and view all the answers

What is the characteristic pattern of PR intervals in a second-degree Mobitz I block?

Progressively longer PR intervals Signup and view all the answers

What is the common ratio of conduction in a second-degree Mobitz I block?

5:4, 4:3, 3:2, or 2:1 Signup and view all the answers

What is the usual cause of second-degree AV block, Mobitz II?

Acute MI and septal necrosis Signup and view all the answers

What is the typical ventricular rate in a second-degree Mobitz II block?

Bradycardic Signup and view all the answers

What is the significance of a second-degree Mobitz II block?

It can compromise cardiac output Signup and view all the answers

What is the typical treatment for a second-degree Mobitz II block?

Usually unnecessary unless signs of poor perfusion are present Signup and view all the answers

What is the characteristic of the QRS complex in a second-degree Mobitz II block?

It is often more than 0.12 second Signup and view all the answers

What is the significance of a first-degree block?

It is usually no danger in itself Signup and view all the answers

What is the typical feature of premature junctional contractions in lead II?

Inverted P waves Signup and view all the answers

What is the typical rate of the AV node in junctional escape rhythm?

40-60 beats per minute Signup and view all the answers

What is the clinical significance of frequent premature junctional contractions?

Indicate organic heart disease Signup and view all the answers

What is the typical pacemaker site in junctional escape beat?

AV junction Signup and view all the answers

What is the typical QRS complex duration in premature junctional contractions?

Usually normal Signup and view all the answers

What is the typical etiology of junctional escape rhythm?

Increased vagal tone Signup and view all the answers

What is the typical PR interval in premature junctional contractions?

Less than 0.12 second Signup and view all the answers

What is the typical clinical significance of junctional escape rhythm?

May decrease cardiac output Signup and view all the answers

What is the typical treatment for junctional escape rhythm?

Observation only Signup and view all the answers

What is the typical rhythm in junctional escape rhythm?

Regular Signup and view all the answers

What is the primary indication for treatment of junctional bradycardia?

Signs of poor perfusion Signup and view all the answers

What is the maximum cumulative dose of atropine sulfate that can be administered for junctional bradycardia?

3.0 mg Signup and view all the answers

What is the characteristic of the PR interval if the P wave occurs before the QRS complex in junctional bradycardia?