Which medical device involves a small balloon at the end and is utilized in certain cardiac procedures?

The balloon catheter is specifically designed for use in various cardiac procedures, making it the appropriate choice in this context. It features a small balloon located at its tip, which can be inflated during medical procedures to dilate narrowed or obstructed blood vessels. This is particularly useful in procedures such as angioplasty, where the goal is to restore proper blood flow in the coronary arteries. The inflatable balloon allows for the effective treatment of blockages without the need for more invasive surgical intervention.

Other devices listed do not have the integral function of a balloon for dilation or expanding blood vessels. A stethoscope is used primarily for auscultation, allowing healthcare providers to listen to internal sounds of a patient's body but has no direct involvement in cardiac interventions. A defibrillator is designed to deliver a shock to restore a normal heart rhythm during cardiac arrest, but it does not utilize a balloon mechanism. Similarly, an electrocardiogram is a diagnostic tool that records the electrical activity of the heart, providing essential information about heart rhythms but not involved in any physical manipulation or treatment of the heart structure. Hence, the balloon catheter stands out as the device specifically employing a balloon for procedural interventions in cardiology.