Question
Assertion: High spinal block above the level of T4, will lead to severe bradycardia along with hypotension.
Reason: The sympathetic supply to heart arises from below the level of T4
| A. |
Both A & R are correct and R is the correct explanation for A.
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| B. |
Both A & R are correct and R is not the correct explanation for A.
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| C. |
A is correct but R is incorrect
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| D. |
A is incorrect but R is correct
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Show Answer
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Correct Answer » C
Explanation
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A high spinal block extending above the T4 level blocks the cardiac sympathetic fibers, resulting in:
- Sympathetic blockade causing peripheral vasodilation → hypotension.
- Blockade of the cardioaccelerator fibers (T1–T4) → unopposed vagal activity → severe bradycardia.
- In very high blocks, profound hypotension, severe bradycardia, and even cardiac arrest may occur.
Thus, the Assertion is correct.
However, the Reason is incorrect because the sympathetic supply to the heart arises from T1–T4 (sometimes described as T1–T5), not below T4. Blocking these segments produces the cardiovascular effects seen in a high spinal block.
