Having trouble refactoring an IEnumerator method with multiple yields

The gist of my code is as follows:

 // Play the first beat
 audio.PlayOneShot(beat);
 
 // Show 1st heartbeat border flash
 TweenAlpha.Begin(heartbeatPanel.gameObject, 0.1f, currentStress);
 yield return new WaitForSeconds(0.1f);
 TweenAlpha.Begin(heartbeatPanel.gameObject, 0.5f, 0);
 
 yield return new WaitForSeconds(interval);
 
 // Play the second beat
 audio.PlayOneShot(beat);
 
 // Show 2nd heartbeat border flash
 TweenAlpha.Begin(heartbeatPanel.gameObject, 0.1f, currentStress);
 yield return new WaitForSeconds(0.1f);
 TweenAlpha.Begin(heartbeatPanel.gameObject, 0.5f, 0);
 
 yield return new WaitForSeconds(interval * 2);

Now I want to split the above code into a single IEnumerator method with 2 calls.

This is what I came up with:

 StartCoroutine(PlayBeat(currentStress, interval));
 StartCoroutine(PlayBeat(currentStress, interval * 2));

 // ...

 IEnumerator PlayBeat(float currentStress, float interval)
 {
      audio.PlayOneShot(beat);

      TweenAlpha.Begin(heartbeatPanel.gameObject, 0.1f, currentStress);
      yield return new WaitForSeconds(0.1f);
      TweenAlpha.Begin(heartbeatPanel.gameObject, 0.5f, 0);

      yield return new WaitForSeconds(interval);
 }

The problem with this is that it doesn't work, hence why I'm asking the question.

What's the best way to extract my two repetitive blocks of code above into a single IEnumerator method?