I run out of breath and my chest tightens when I talk on conference calls or meetings. What are possible interventions?

Anxiety. You get very anxious and have almost panic attack. Dessenstization counselling may be of help or anxiolytics. See a psychiatriast.
Merits evaluation. See your doctor or a cardiologist for a thorough examination to elucidate the underlying cause of your symptoms. It is usually quite easy to determine and answers can usually be obtained quite rapidly.