Heart Sounds Tutorial

Table of Contents

1. Introduction
2. The Basics
3. Murmurs
   1. Benign murmurs
   2. Murmurs II
   3. Aortic Stenosis
   4. Mitral Regurgitation
   5. Aortic Regurgitation
   6. Mitral Stenosis
   7. Tricuspid Valve
   8. Pulmonic Valve
   9. Ventricular Septal Defect
   10. Patent Ductus Arteriosus
   11. Atrial Septal Defect
   12. Coarctation of the Aorta
   13. Mitral Valve Prolapse
4. Extracardiac Sounds
5. MCQ
6. Acknowledgements and References

Patent Ductus Arteriosus

In the fetus the ductus arteriosus is what stops blood going to the lungs from the RV. The ductus arteriosus goes from the pulmonary artery and attaches to the descending aorta. This shunt usually closes a few days after birth and becomes the ligamentum arteriousm.

In a patent ductus arteriosus (PDA) there is effectively free circulation between the systemic and pulmonary circulations.

However...

If the pulmonary resistance is high, there can be a Right-to-Left shunt so de-oxygenated blood will enter the descending aorta, this is a reversing of the shunt.

1

Regarding the statement above, if de-oxygenated blood is entering the descending aorta which of the following could occur? a) Cyanosis of the Hands b) Cyanosis of the Feet c) Clubbing of the Feet d) Clubbing of the Hands Yes, as hypoxemic blood will lead to a lack of oxygen being delivered to the lower limbs and so clubbing and cyanosis will occur in feet but not handsNo, as hypoxemic blood will lead to a lack of oxygen being delivered to the lower limbs and so clubbing and cyanosis will occur in feet but not handsYour answer has been saved.

A situation where there is reversing of a left to right shunt to a right to left shunt is called Eisenmenger's Syndrome and will have signs as detailed in the answers to the above question. This syndrome can also occur in a VSD.

The following is an example of a PDA, again listen with headphones, or decent speakers otherwise you could miss the continuous 'machinery' murmur

PDA