If you can, I'd recommend taking a cardiac anesthesia elective alone or in addition to a general anesthesia elective..
That stuff kicks it! You get to do things (in addition to intubating, also a-lines, central lines, IV's) and learn lots of practical physiology to boot.
Look at the know-how and skills needed for the types of cases:
anesthesia management in the face of major sympathetic stimulation (i.e., cracking the chest and so forth)
restarting the heart after bypass,
managing arrhythmias,
managing heart failure,
managing hemodynamics in the face of valvular disease (multiple valves sometimes),
managing labile hemodynamics,
analyzing swan-ganz parameters on a second to second basis,
managing MAJOR fluid shifts & acid-base issues after coming off clamp in thoraco-abdominal-aortic aneurysm repairs,
stopping ALL circulation ("circ-arrest") in ascending arch repairs (i.e. NO bypass),
diangosing/correcting acid-base & electolyte imbalances,
learning how to read trans-esophageal echocardiography in the different modes and functions (at least an intro into this),
how to use the setting of pacemakers, aortic ballon pumps,
when / how to give various blood products, aprotinin, amicar, heparin reversal, different autonomic meds, etc.
and much more!