Representative Henry A. Waxman (D-Calif.) and chairman of the Committee on Oversight and Government Reform asked the FDA why defibrillator leads were not tested and scrutinized like defibrillators.

Waxman asked the FDA to provide information about how it determines how much to test leads before marketing and why the agency does not give leads the same scrutiny that it has given in recent years to other heart devices like defibrillators.

A defibrillator is an implanted device that sends out a jolt of electricity to restore a wildly beating heart to normal rhythm. Medtronic, the lead maker, disclosed that a widely used heart lead produced by the company was fracturing and preventing the flow of electricity between the heart and defibrillator.

Some experts believe that the Medtronic lead was prone to fracturing because it was the thinnest lead ever made by the company and might not have been durable enough. Defibrillator leads are known to fracture, but neither the FDA nor device makers have developed effective ways to track such episodes.

The FDA’s Center for Devices and Radiological Health may be reviewing whether to require more strenuous laboratory testing of such products before they go on the market.