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Question #46372
The Question
In a clinical Electrocardiogram (ECG), a patient exhibits a significantly widened QRS complex, while the P wave remains normal. Based on the sequence of the cardiac conducting system, which of the following is the most accurate physiological explanation for this anomaly and its immediate mechanical consequence?
Options
- A.
A conduction block in the Purkinje fibers, resulting in asynchronous ventricular depolarization and a subsequent reduction in stroke volume.
- B.
A delay in the transmission of the action potential at the AV node, leading to prolonged ventricular systole and increased cardiac output.
- C.
Rapid firing of the Sino-Atrial (SA) node, causing overlapping atrial and ventricular contractions within the rigid boundaries of the thoracic cage.
- D.
Failure of the ventricular myocardium to repolarize simultaneously, leading to an extended T-wave and increased end-systolic volume.
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Correct Answer
Step-by-Step Solution
Explanation
How the Examiner Thinks
Regulatory_Failure
Understand how NOT, EXCEPT, and logical constraints are used to manipulate exam results.
Concepts Behind This Question
ECG Wave Interpretation|Conducting System Sequence|Axial Skeleton Count
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Students often memorize 'QRS = Ventricular Depolarization' but fail to link the width (duration) of the wave to the conduction velocity of the Purkinje fibers.
The trap lies in confusing AV node delay (PR interval) with ventricular conduction blocks (QRS width), and failing to connect the electrical anomaly to its mechanical consequence (asynchronous contraction reducing stroke volume).
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Body Fluids and Circulation - Class 11 |
| Concept | ECG Wave Interpretation |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |