The Question is from neet-zoology body-fluids-and-circulation , and it was created by the author A SUBRAMANYAM

Question

A patient presents with an ECG showing a PR interval of 0.24 seconds, a QRS complex duration of 0.08 seconds, and a heart rate of 70 bpm.  No delta waves are present. Which of the following is the MOST likely diagnosis?

A SUBRAMANYAM · Accepted Answer

## CORE INFORMATION
✓ **Answer**: A
## CONCEPT FRAMEWORK
 **Primary Concept**: ECG interpretation and heart block classification.
 **Related Topics**: Cardiac conduction system, PR interval, QRS complex duration, delta waves.
 **Prerequisites**: Understanding of normal ECG parameters and the different types of AV blocks.
## SOLUTION PATHWAY
**Given Information**:
  PR interval = 0.24 seconds
  QRS complex duration = 0.08 seconds
  Heart rate = 70 bpm
  No delta waves present
**Method & Steps**:
 1. Analyze the PR interval.
  Reasoning: The normal PR interval is 0.12-0.20 seconds. A PR interval > 0.20 seconds indicates a delay in AV nodal conduction.
  Formula/Rule: None directly applicable, but knowledge of normal PR interval range is crucial.
 2. Analyze the QRS complex duration.
  Working: The QRS complex duration of 0.08 seconds is within the normal range (0.06-0.10 seconds), indicating normal ventricular depolarization.
  Key Point: A prolonged QRS complex (>0.10 seconds) often suggests a bundle branch block or other ventricular conduction abnormality.
 3. Consider the absence of delta waves and the heart rate.
  Result: The prolonged PR interval, normal QRS duration, absence of delta waves, and normal heart rate are consistent with a first-degree AV block.  Second-degree AV block (Mobitz Type I) would show progressively lengthening PR intervals before a dropped beat. Third-degree AV block would show complete dissociation between atrial and ventricular activity. Wolff-Parkinson-White syndrome is characterized by the presence of delta waves.
  Verification: The findings align perfectly with the diagnostic criteria for first-degree AV block.
 ## OPTION ANALYSIS
A ✓: First-degree AV block: Correct. This diagnosis aligns with the prolonged PR interval and normal QRS complex and heart rate.
B :x: Second-degree AV block (Mobitz Type I): Incorrect. Mobitz Type I is characterized by progressively lengthening PR intervals until a QRS complex is dropped. This ECG shows a constant, prolonged PR interval.
C :x: Third-degree AV block: Incorrect. Third-degree AV block shows complete dissociation between atrial and ventricular rhythms, which is not present here.
D :x: Wolff-Parkinson-White syndrome: Incorrect. This syndrome is characterized by the presence of delta waves, which are explicitly absent in this case.
 ## LEARNING AIDS
 **Common Mistakes**:
  1.Confusing first-degree AV block with other types of AV blocks: Pay close attention to the PR interval pattern and the presence or absence of dropped beats.
  2.Overlooking the significance of the QRS complex duration: A prolonged QRS complex can indicate other conditions that need to be considered.
 **Quick Tips**:
  1.Remember the normal ranges for PR interval and QRS duration.
  2.Systematically analyze ECG parameters: PR interval, QRS duration, heart rate, and presence of any abnormalities like delta waves.

A SUBRAMANYAM · Answer

The correct Option is "First-degree AV block"

A SUBRAMANYAM · Answer

Second-degree AV block (Mobitz Type I)

A SUBRAMANYAM · Answer

Third-degree AV block

A SUBRAMANYAM · Answer

Wolff-Parkinson-White syndrome

NEET Zoology Body Fluids And Circulation MCQs

Select Topic

Question Tags

Question Tags

Question Tags

Question Tags

Question Tags

Question Tags

Question Tags

Question Tags

Question Tags

Question Tags

NEET Subjects

Our Bots

Company