Answer
The **cardiac output** (CO) is the amount of blood pumped by the heart per minute and is calculated by multiplying the heart rate (HR) and stroke volume (SV):
\[ CO = HR \times SV \]
In this scenario, the initial cardiac output is calculated as:
Initial CO = Initial HR × Initial SV
Initial CO = 70 bpm × 70 mL = 4900 mL/min
After the negative inotropic agent reduces the stroke volume to 50 mL, the new cardiac output needs to be maintained at the same level. Let's denote the new heart rate as \( x \) bpm. The equation for the new cardiac output can be set up as:
New CO = New HR × New SV
4900 mL/min = x bpm × 50 mL
Solving for \( x \), the new heart rate required to maintain the same cardiac output is:
\[ x = \frac{4900 \, \text{mL/min}}{50 \, \text{mL}} \approx 98 \, \text{bpm} \]
Therefore, in order to maintain the same cardiac output of 4900 mL/min with a reduced stroke volume of 50 mL, the new heart rate would need to be approximately 98 bpm.
Work Step by Step
The **cardiac output** (CO) is the amount of blood pumped by the heart per minute and is calculated by multiplying the heart rate (HR) and stroke volume (SV):
\[ CO = HR \times SV \]
In this scenario, the initial cardiac output is calculated as:
Initial CO = Initial HR × Initial SV
Initial CO = 70 bpm × 70 mL = 4900 mL/min
After the negative inotropic agent reduces the stroke volume to 50 mL, the new cardiac output needs to be maintained at the same level. Let's denote the new heart rate as \( x \) bpm. The equation for the new cardiac output can be set up as:
New CO = New HR × New SV
4900 mL/min = x bpm × 50 mL
Solving for \( x \), the new heart rate required to maintain the same cardiac output is:
\[ x = \frac{4900 \, \text{mL/min}}{50 \, \text{mL}} \approx 98 \, \text{bpm} \]
Therefore, in order to maintain the same cardiac output of 4900 mL/min with a reduced stroke volume of 50 mL, the new heart rate would need to be approximately 98 bpm.
