Find the INCORRECT pairing.

Options

A. SAN - Natural pacemaker
B. Heart rate - Pulse rate
C. Cardiac output - Heart rate x Stroke volume
D. Heart failure - Heart attack

Answer

To solve the question "Find the INCORRECT pairing," we will analyze each option provided and determine if the pairings are correct or incorrect.

### Step-by-Step Solution:

1. **Analyze Option A: SAN and Natural Pacemaker**
- SAN stands for Sinoatrial Node, which is indeed known as the natural pacemaker of the heart.
- **Conclusion**: This pairing is **correct**.

2. **Analyze Option B: Heart Rate and Pulse Rate**
- Heart rate is defined as the number of times the heart beats per minute, and pulse rate is often used interchangeably with heart rate as it reflects the same measurement.
- **Conclusion**: This pairing is **correct**.

3. **Analyze Option C: Cardiac Output and Heart Rate multiplied by Stroke Volume**
- Cardiac output is calculated as the product of heart rate and stroke volume (CO = HR x SV).
- **Conclusion**: This pairing is **correct**.

4. **Analyze Option D: Heart Failure and Heart Attack**
- Heart failure refers to a condition where the heart is unable to pump blood effectively, leading to congestion and fluid buildup. Heart attack, on the other hand, is an acute condition where blood flow to a part of the heart is blocked, causing damage to the heart muscle.
- **Conclusion**: This pairing is **incorrect** because heart failure and heart attack are distinct conditions.

### Final Answer:
The **incorrect pairing** is **Option D: Heart Failure and Heart Attack**.

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