Supraventricular Tachycardia: Causes and Characteristics
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Questions and Answers

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?

    <p>Marked reduction in cardiac output</p> Signup and view all the answers

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

    <p>Close to 0.12 second</p> Signup and view all the answers

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

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

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

    <p>It compromises coronary artery perfusion</p> Signup and view all the answers

    What is the atrial rate in atrial flutter?

    <p>250-350 per minute</p> Signup and view all the answers

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

    <p>Both sawtooth and picket fence pattern</p> Signup and view all the answers

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

    <p>Electrical therapy with synchronized cardioversion</p> Signup and view all the answers

    What is the effect of atrial fibrillation on cardiac output?

    <p>It decreases cardiac output by 20-25%</p> Signup and view all the answers

    What is the characteristic rhythm of atrial fibrillation?

    <p>Irregularly irregular</p> Signup and view all the answers

    What is the most common sustained cardiac arrhythmia?

    <p>Atrial fibrillation</p> Signup and view all the answers

    What is the cause of atrial dilation in atrial fibrillation?

    <p>All of the above</p> Signup and view all the answers

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

    <p>Permanent</p> Signup and view all the answers

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

    <p>It compromises cardiac output</p> Signup and view all the answers

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

    <p>Cardiac output decrease</p> Signup and view all the answers

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

    <p>Loss of atrial kick and rapid ventricular response</p> Signup and view all the answers

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

    <p>Obtaining a 12-lead ECG and establishing IV access</p> Signup and view all the answers

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

    <p>To slow the impulse between the atria and the ventricles</p> 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?

    <p>Lower portion of the AV node</p> Signup and view all the answers

    What is the cause of AV blocks?

    <p>All of the above</p> Signup and view all the answers

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

    <p>First-degree, second-degree, and third-degree</p> Signup and view all the answers

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

    <p>A delay in conduction at the level of the AV node</p> Signup and view all the answers

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

    <p>More than 0.20 second</p> Signup and view all the answers

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

    <p>Sinus bradycardia</p> Signup and view all the answers

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

    <p>Usually bradycardic</p> Signup and view all the answers

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

    <p>Two P waves for each QRS complex</p> Signup and view all the answers

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

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

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

    <p>Usually associated with acute MI and septal necrosis</p> Signup and view all the answers

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

    <p>Can be normal or abnormal</p> Signup and view all the answers

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

    <p>Unaffected</p> Signup and view all the answers

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

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

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

    <p>Can develop into full AV block</p> Signup and view all the answers

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

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

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

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

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

    <p>It often leads to a more significant block</p> Signup and view all the answers

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

    <p>Second-degree Mobitz I</p> Signup and view all the answers

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

    <p>Progressively longer PR intervals</p> Signup and view all the answers

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

    <p>5:4, 4:3, 3:2, or 2:1</p> Signup and view all the answers

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

    <p>Acute MI and septal necrosis</p> Signup and view all the answers

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

    <p>Bradycardic</p> Signup and view all the answers

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

    <p>It can compromise cardiac output</p> Signup and view all the answers

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

    <p>Usually unnecessary unless signs of poor perfusion are present</p> Signup and view all the answers

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

    <p>It is often more than 0.12 second</p> Signup and view all the answers

    What is the significance of a first-degree block?

    <p>It is usually no danger in itself</p> Signup and view all the answers

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

    <p>Inverted P waves</p> Signup and view all the answers

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

    <p>40-60 beats per minute</p> Signup and view all the answers

    What is the clinical significance of frequent premature junctional contractions?

    <p>Indicate organic heart disease</p> Signup and view all the answers

    What is the typical pacemaker site in junctional escape beat?

    <p>AV junction</p> Signup and view all the answers

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

    <p>Usually normal</p> Signup and view all the answers

    What is the typical etiology of junctional escape rhythm?

    <p>Increased vagal tone</p> Signup and view all the answers

    What is the typical PR interval in premature junctional contractions?

    <p>Less than 0.12 second</p> Signup and view all the answers

    What is the typical clinical significance of junctional escape rhythm?

    <p>May decrease cardiac output</p> Signup and view all the answers

    What is the typical treatment for junctional escape rhythm?

    <p>Observation only</p> Signup and view all the answers

    What is the typical rhythm in junctional escape rhythm?

    <p>Regular</p> Signup and view all the answers

    What is the primary indication for treatment of junctional bradycardia?

    <p>Signs of poor perfusion</p> Signup and view all the answers

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

    <p>3.0 mg</p> 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?

    <p>Less than 0.12 second</p> Signup and view all the answers

    What is the underlying cause of accelerated junctional rhythm?

    <p>Ischemia of the AV junction</p> Signup and view all the answers

    What is the typical heart rate range for accelerated junctional rhythm?

    <p>60-100 beats per minute</p> Signup and view all the answers

    What is the effect of junctional bradycardia on cardiac output?

    <p>Decreases cardiac output</p> Signup and view all the answers

    What is the characteristic of the P waves in junctional bradycardia?

    <p>Inverted and can appear before or after the QRS complex</p> Signup and view all the answers

    What is the primary rationale for administering atropine sulfate in junctional bradycardia?

    <p>To increase the heart rate</p> Signup and view all the answers

    What is the characteristic of the QRS complex in accelerated junctional rhythm?

    <p>Normal</p> Signup and view all the answers

    What is the indication for transcutaneous pacing in junctional bradycardia?

    <p>Signs of poor perfusion</p> Signup and view all the answers

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