Exam 20: Heart and Neck Vessels

The nurse is performing a cardiac assessment of a 65-year-old patient 3 days after her myocardial infarction (MI).Heart sounds are normal when she is supine, but when she is sitting and leaning forward, the nurse hears a high-pitched, scratchy sound with the diaphragm of the stethoscope at the apex.It disappears on inspiration.The nurse suspects:

A 70-year-old patient with a history of hypertension has a blood pressure of 180/100 mm Hg and a heart rate of 90 beats per minute.The nurse hears an extra heart sound at the apex immediately before S₁.The sound is heard only with the bell of the stethoscope while the patient is in the left lateral position.With these findings and the patient's history, the nurse knows that this extra heart sound is most likely a(n):

The component of the conduction system referred to as the pacemaker of the heart is the: