Final answer:
The murmur of mitral regurgitation is best heard at the heart's apex and may be affected by the patient's breathing techniques during auscultation.
Step-by-step explanation:
The murmur of mitral regurgitation is best heard at the apex of the heart, which is located at the bottom tip of the heart on the left side, often found around the 5th intercostal space in line with the midclavicular line. This type of heart murmur is classified as a systolic murmur which occurs when the heart muscle contracts. It is often described by clinicians as a high-pitched, blowing sound, which may intensify when the patient changes position, particularly when moving from a lying down to a sitting or standing position.
In terms of auscultation, it's also important to note that heart murmurs may be more pronounced during certain respiratory maneuvers. As a rule, the clinician may instruct the patient to breathe deeply during auscultation to better distinguish the murmur, as inhalation and exhalation can affect the amplitude of heart murmurs.