Heart Rate Dropping to 30

My 73 year old mother was scheduled for angioplast surgery in her legs today but the surgery was cancelled because her heart rate kept dropping as low as 30bpm.  Her doctor suggested she see a cardiologist sometime in the next few weeks.  What would cause the heart rate to drop that low?  Her doctor doesn't seem to be very concerned; should I be? Is it time to find another doctor?

[ireneo]

A rate that low is called "bradycardia." There are a few different causes but primarily she needs to find out how often it occurs and whether she'll need a pacemaker. That would keep her heart rate up where it belongs.  Has she mentioned having any light headedness or fainting?

[txifonly]

Thank you for the info.  No, she has not had any light headedness or fainting.  She said she felt no difference this morning when her heart rate was dropping so low.  She had a stress test (chemical) a few weeks ago along with an echo and it came back normal.