funny its seems like alot of you are outta shape.
hearts wise that is. Just like all the other muscles you work out, the heart is also a muscle. And like your arms and leg can hit a catabolic state. And if your heart rate is around 170 (holy shit that is high) it probably is going to be in a catabolic state.
Its really important to strength the heart, and weight lifting doesn't do that (arnold had two heart surgeries you know). Best way to do this is on a treadmill, ellipical, or bike, where you can monitor your heartrate. You usually wanna shot a number between 130 to 145 and keep it at the rate for 10 to 25 minutes. Not too long or else you'll be at a catabolic rate again. The best measure is to listen to your body.
Do a test, and put a heartbeat monitor on while you workout. (the chest strap ones). About mid way threw take a reading. If the number is high (180s) and you hadn't done any squads or deadlifts, then you need to stop weightlifting and strengthen your heart. Done be too surprized many top olympic atheletes have heart problems, why cause they push their bodies and their heart can't keep up.
Best way to solve this is to take about 3 months and do cardio every week with a 1 to 2 day rest peroid. You can weight lift, only if its light weight, high reps, controlled movement, and never where you have to catch your breath at the end of the set.
After that go back to weight lifting and measure your heart again and make a call if you need to do more cardio or not.