At which grade can a thrill be palpated when assessing for a cardiac murmur?

A thrill is a palpable vibration that can be felt over the chest wall and is indicative of more significant turbulence of blood flow, often associated with moderate to severe cardiac murmurs. In the grading system for heart murmurs, a thrill is typically associated with a Grade IV murmur.

Grade I murmurs are very faint and may not be heard by everyone, while Grade II murmurs are easily audible but still do not cause significant turbulence that would produce a thrill. Grade III murmurs are louder and can be easily heard with a stethoscope, but they still do not produce the level of turbulence needed to generate a palpable thrill.

Once you reach Grade IV, the murmur is not only loud but also causes enough of a change in blood flow dynamics to create a disturbance that can be felt, hence the presence of a thrill. Therefore, identifying a thrill during an assessment suggests that the murmur is clinically significant, corresponding with a Grade IV level or higher.

Grade V murmurs are extremely loud and can be heard with one edge of the stethoscope off the chest, and they definitely have a thrill, but the question specifically pertains to the lowest grade at which a thrill can be palpated, which is Grade IV.