Not sure this is a totally sane way of structuring the data, but … what can I say, I like dictionaries.

heartsdict.py

import random

hearts = {
    "QR001": [5, 38],
    "QR002": [15, 60],
    "QR004": [0, 00],
    "QR005": [3, 92],
    "QR093": [0, 92]
}

print hearts["QR002"]

# OK, so we have a dictionary of QR references, each with a list datastructure of index number and heart rate. Or something like that.

# This will output the index associated with a QR reference:
print hearts["QR002"][0]
# And this, the heart rate:
print hearts["QR002"][1]

# Can then check if we have this QR code logged:
print "QR005" in hearts
print "QR003" in hearts

emptylist = []
for key, val in hearts.items():
    if (val[0] == 0):
        emptylist.append(key)

print emptylist
select = random.choice(emptylist)
hearts[select][0] = "TADA!"

print hearts