Since my original post I've researched Yerba Maté (or Maté for short) a bit more after seeing the beautiful Brooke Burke touting it's many benefits on a segment of Wild On...something South American. This stuff is everywhere in Argentina, Uraguay, Paraguay and Brazil. Check out
http://www.noborders.net/mate/index.html for more info. This stuff seems to have some great health benefits as it's a tea. Check it out, I'm getting stoked just reading about all the health benefits!
As for your increased heart rate, here's a snippet from the website mentioned above about Maté and it's cardiovascular effects:
CARDIOVASCULAR EFFECTS
Heart Ailments of all kinds have been treated or prevented through Yerba Mate use. Yerba Mate supplies many of the nutrients required by the heart for growth and repair. In addition, it increases the supply of oxygen to the heart, especially during periods of stress or exercise. Mate has become a favorite of body builders and anyone interested in the health benefits of exercise. The metabolic effects of Mate appear to include the ability to maintain aerobic glycolysis (breakdown of carbohydrates) during exercise for longer periods of time. This results in burning more calories, increasing cardiac efficiency, and delaying anaerobic glycolysis and the resulting buildup of lactic acid during exercise. Reports of Mate reducing blood pressure are not uncommon.
Sean