Lab 7

Heart Sounds

1. Why is the second heart sound higher in pitch than the first heart sound?

   • The second heart sound (S2) is higher in pitch than the first heart sound (S1) because the semilunar valves (aortic and pulmonary) involved in S2 have thinner, more taut leaflets than the atrioventricular (AV) valves (mitral and tricuspid) involved in S1. Additionally, the higher pressure in the aorta and pulmonary artery during valve closure contributes to the higher pitch.

2. What might the presence of third and fourth heart sounds indicate if they can be heard through normal auscultation?

   • Third heart sound (S3): Often indicates increased ventricular filling pressure, which may be due to heart failure or volume overload (e.g., mitral regurgitation).

   • Fourth heart sound (S4): Suggests a stiff or hypertrophic ventricle, typically associated with conditions like left ventricular hypertrophy (LVH) or ischemic heart disease.

EKG/ECG

3. What pathology would be associated with a prolonged QT interval?

   • A prolonged QT interval is associated with an increased risk of ventricular arrhythmias such as torsades de pointes. It can be caused by congenital long QT syndrome, electrolyte imbalances (e.g., low potassium, calcium, or magnesium), medications (e.g., antiarrhythmics, antipsychotics), or myocardial ischemia.

4. How would physical exercise affect the amplitude and duration of the QRS complex?

   • Amplitude: Increases due to greater ventricular depolarization and increased sympathetic activity.

   • Duration: Usually remains unchanged or slightly decreases due to enhanced conduction velocity from increased sympathetic tone.

Ultrasound

5. What can features of the heart visible through ultrasound reveal about heart health?

   • Chamber size and wall thickness – Can indicate hypertrophy or dilation.

   • Valve function – Detects regurgitation, stenosis, or prolapse.

   • Pericardial effusion – Fluid accumulation around the heart.

   • Myocardial contractility – Assesses overall heart pumping function.

   • Presence of thrombi or masses – May indicate a risk for embolism.

6. What is ejection fraction (EF)? How do you calculate EF?

   • Ejection Fraction (EF) is the percentage of blood ejected from the left ventricle during systole.

   • Formula:

   EF=(End-Diastolic Volume - End-Systolic Volume)End-Diastolic Volume×100EF = \frac{\text{(End-Diastolic Volume - End-Systolic Volume)}}{\text{End-Diastolic Volume}} \times 100EF=End-Diastolic Volume(End-Diastolic Volume - End-Systolic Volume)​×100

7. What measurements can be taken through ultrasound to also calculate ejection fraction?

   • End-diastolic volume (EDV) – Volume of blood in the left ventricle at the end of diastole.

   • End-systolic volume (ESV) – Volume of blood in the left ventricle at the end of systole.

   • Measured using 2D echocardiography or M-mode echocardiography with Simpson’s method or Teichholz method.