The use of ungating with the Medstone lithotriptor

Ungating using the Medstone* lithotriptor by 200 urologists was evaluated.

During 1994, 3,288 patients were treated by 200 urologists at 46 sites in 6 upper midwest states using 5 fixed and 3 mobile Medstone lithotriptors. Ungating was used with 58 treatments in 57 asymptomatic patients (1.8%) due to irregular cardiac rhythm in 48 caused by a bundle branch block (11), atrial fibrillation (10), slow heart rate (6) and irregular cardiac complex (21); all 48 cases were clinically insignificant, and because of urologist choice in 9 with normal cardiac rhythm (10 treatments). The cardiac simulator used for ungated lithotripsy was set at 85 shocks per minute for irregular cardiac rhythm and at 120 shocks per minute for elective use.

The 48 treatments in patients with clinically insignificant irregular cardiac rhythm (average age 66.4 years) were performed during an average of 41 minutes of shock time. One patient had clinically significant cardiac arrhythmia that resolved with gating. The 10 elective treatments were performed during an average of 34 minutes of shock time in patients an average of 60.4 years old. The 3,231 gated treatments were performed during an average of 40 minutes of shock time in patients an average of 51 years old.

Ungating was safe and effective in allowing patients with an irregular cardiac rhythm to be treated with the same shock time as gated cases (normal cardiac rhythm).