They hope the technology could eventually help more people suffering from heart palpitations.
The Arrythmia Alliance described the tests as a "fantastic development."
The work is in its early stages - doctors have used the vests on 40 patients so far.
However, they are impressed with the precision that each vest can give them.
The panels contain about 250 electrodes, to determine exactly where abnormal electrical activity in the heart is causing problems.
Computer images are then generated to produce an "electrical map" of the patient's heart.
Using this technology - known as the ECVUE system - means that a subsequent procedure called ablation - in which a catheter is placed in the heart through veins in the leg and then used to burn away the problematic area - stands a better chance of success.
Dr Prapa Kanagaratnam, the consultant cardiologist leading the work, said, "it was very appealing right from the start to be able to get measurements of the heart's electrical activity with that degree of precision, without having to initially put wires into the heart."
Each vest costs about 1,000 pounds - the doctors say this compares well with conventional diagnosis techniques, especially given the benefit of treating patients they were sometimes not able to previously help.