Shocking Elevation

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Bill Etiz, D.O.

It’s common to note EKG artifacts during ESWL, however, they subside immediately after shock cessation.  The following case describes an instance when changes did not instantly terminate.   --  SS

A 67 year old male with a history of hypertension and a solitary left upper pole renal stone presented for lithotripsy.  Pre op EKG revealed NSR with non specific ST changes; a cardiac study six months prior demonstrated a normal Echo, EF = 69%, a negative stress test, and a normal myocardial perfusion scan.  The patient took his beta blocker on the morning of surgery.

The patient received general anesthesia, breathing 100% O2 spontaneously at 1 MAC of sevoflurane.  Standard shock protocol was used.  At 600 shocks at level 6 marked ST elevation was noted.  The heart rate was 70 and blood pressure 100/58.  I instructed the technician to stop shock therapy, and over the course of the next minute the ST segments returned to baseline. 

“How close is the shock wave from the heart?” I asked the technician.

“About 2 or 3 inches,” he replied.

Lithotripsy recommenced, but the ST elevation returned both in the gated and non gated mode.  The procedure was terminated after 1500 shocks, and again the segments returned to baseline in about a minute.  The patient awoke in PACU uneventfully, and an EKG showed no change from the pre op study.

Is it possible the ST elevation was due to vasospasm of the lower coronary vessels as a result of the close proximity of the shock wave?  When discussing the case with a cardiologist, he felt Prinzmetal’s angina the likely cause.

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