Table of contents

1. Introduction to Anatomy & Physiology5h 43m
2. Cell Chemistry & Cell Components12h 36m
3. Energy & Cell Processes10h 6m
4. Tissues & Histology10h 3m
5. Integumentary System2h 20m
6. Bones & Skeletal Tissue2h 16m
7. The Skeletal System2h 35m
8. Joints2h 17m
9. Muscle Tissue2h 33m
10. Muscles1h 11m
11. Nervous Tissue and Nervous System1h 35m
12. The Central Nervous System1h 6m
- Introduction to the Central Nervous System
  18m
- The Cerebrum
  48m
13. The Peripheral Nervous System1h 26m
14. The Autonomic Nervous System1h 38m
15. The Special Senses2h 41m
16. The Endocrine System2h 48m
17. The Blood3h 22m
18. The Heart3h 42m
19. The Blood Vessels3h 35m
20. The Lymphatic System3h 16m
21. The Immune System14h 37m
22. The Respiratory System3h 20m
23. The Digestive System2h 5m
24. Metabolism and Nutrition4h 0m
25. The Urinary System2h 39m
26. Fluid and Electrolyte Balance, Acid Base Balance37m
27. The Reproductive System2h 5m
28. Human Development1h 21m
29. Heredity3h 32m

18. The Heart

Cardiac Cycle

Anatomy & Physiology

18. The Heart

Cardiac Cycle

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1:51 minutes

Problem 21

Textbook Question

You have been called upon to demonstrate the technique for listening to valve sounds.
Explain where you would position your stethoscope to auscultate.
(1) the aortic valve of a patient with severe aortic valve insufficiency and
(2) a stenotic mitral valve.
During which period(s) would you hear these abnormal valve sounds most clearly? (During atrial diastole, ventricular systole, ventricular diastole, or atrial systole?)
What cues would you use to differentiate between an insufficient and a stenotic valve?

Verified step by step guidance

Step 1: To auscultate the aortic valve, position the stethoscope at the second intercostal space, right of the sternum. This is the anatomical location where the sound of the aortic valve is best transmitted. For severe aortic valve insufficiency, abnormal sounds are most clearly heard during ventricular diastole, as blood flows back into the left ventricle due to the valve's inability to close properly.

Step 2: To auscultate the mitral valve, position the stethoscope at the fifth intercostal space, near the midclavicular line on the left side. This is the anatomical location where the sound of the mitral valve is best transmitted. For a stenotic mitral valve, abnormal sounds are most clearly heard during atrial diastole, as blood flows through the narrowed valve into the left ventricle.

Step 3: Differentiate between an insufficient valve and a stenotic valve by analyzing the type of sound produced. An insufficient valve typically produces a regurgitant murmur, which is a blowing or whooshing sound caused by blood flowing backward through the valve. A stenotic valve produces a harsh, rumbling sound due to turbulent blood flow through the narrowed valve opening.

Step 4: Use timing cues to further differentiate the valve abnormalities. For aortic valve insufficiency, the murmur is heard during ventricular diastole, while for mitral valve stenosis, the murmur is heard during atrial diastole. The timing of the murmur in relation to the cardiac cycle is critical for diagnosis.

Step 5: Consider additional diagnostic cues such as the intensity and location of the murmur, as well as any associated symptoms like shortness of breath or fatigue. These can provide further evidence to confirm whether the valve is insufficient or stenotic.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Auscultation Techniques

Auscultation is the process of listening to internal body sounds, typically using a stethoscope. For heart valves, specific locations on the chest are designated for optimal sound detection. For instance, the aortic valve is best auscultated at the second right intercostal space, while the mitral valve is typically heard at the fifth left intercostal space near the midclavicular line. Understanding these positions is crucial for accurately identifying valve sounds.

Valve Insufficiency vs. Stenosis

Valve insufficiency occurs when a valve does not close properly, leading to backflow of blood, while stenosis refers to a narrowing of the valve opening, restricting blood flow. In aortic valve insufficiency, a characteristic 'whooshing' sound may be heard during diastole, whereas mitral stenosis produces a distinct 'snap' or 'murmur' during diastole. Recognizing these differences is essential for accurate diagnosis.

Cardiac Cycle Phases

The cardiac cycle consists of phases including atrial systole, ventricular systole, atrial diastole, and ventricular diastole. Abnormal sounds from valves can be correlated with these phases; for example, aortic insufficiency sounds are most prominent during ventricular diastole, while mitral stenosis sounds are best heard during atrial diastole. Understanding these phases helps in timing the auscultation to capture the relevant sounds.