The recommendations for spark gap lithotripters include that the shock waves must be delivered according to the ECG, avoiding the discharge during the refractory part of the heart activity. The lithotripters we have in our department does not have from the factory an ECG correlated triggering system. Observing that ESWL for patients without heart problems did not induced arrhythmias, we decide to perform this procedure under strict cardiologic supervision to the patients having arrhythmias (chronic fibrillation, chronic atrial fibrillation, supraventricular arrhythmias, supraventricular premature beats, ventricular premature beats, ventricular tachycardia). All the ESWIL sessions did not have any major incidents and all the patients return home safe, without any changes of the cardiac medication. Even we did not notice any aggravation of the cardiac arrhythmias during ESWL we consider that the careful monitoring of the patients by the cardiologist is necessary during the procedure, most of all when the spark gap lithotripter has not an ECG triggering system.