Heart Sounds/Wigger Diagram Flashcards
Aortic valve opens
After isovolumetric contraction, after mitral valve is shut and the ventricles are contracting, a high enough pressure in the ventricles is obtained which overcomes the aortic pressure and the valve opens. After this, we see ejection. Ejection slams into the mitral valve, which causes the “c” wave.
Mitral valve closes
This valve separates the left atrium and ventricle. The mitral valve shuts right when the ventricle is depolarized and starts contracting. The initial addition of a little bit of pressure from the ventricular contraction shuts the mitral valve. After this, isovolumic contraction is taking place. When enough pressure is reached (when the aortic pressure is surpassed, 80mmHg), the aortic valve opens.
When the mitral valve is shut due to the pressure gradient, blood begins rushing into the atria. The pressure wave created when blood pools into a close-walled atrium is responsible for the “v” wave.
Aortic valve closes
This occurs when the ventricles begin to repolarize and thus stop contracting. Low pressure inside the ventricles after all blood is ejected pulls the valve shut (P goes down since V goes down). The recoil of the stretchy aorta after blood stops rushing through it causes the DICHOTIC NOTCH.
Mitral valve opens
The mitral valve opens again once the isovolumetric relaxation has ceased and the ventricle increases in volume. As it increases in volume, the pressure goes down, which means the atrium has a higher pressure than the ventricle and the blood rushes through mitral valve from the atrium. After 95% of blood has passively passed to the lower pressure area (ventricle), the atrium gives one last small contraction to get the last 5% of blood into the ventricle. This small atrial contraction sends a kickback pressure to the IVC, which causes the “a” wave.
Pressure and volume measurements
Atria: pressure stays below 20 mmHg; volume low
Ventricle: pressure 0-120 mmHg (high at ejection);
volume 20-40ml <-check!!!!!!!
Aorta: pressure 80-120 mmHg (high at ejection)
Heart sounds
1st: closing of the AV valves - isovolumetric contraction
2nd: closing of the semilunar valves - isovolumetric relaxation
3rd: caused by rapid flow of blood into a dilated heart; you hear swooshing - rapid filling phase
4th: caused by vigorous pumping of blood during atrial systole after the “a” wave
Pulmonary capillary wedge pressure
When you stick a catheter with a balloon into pulmonary arteries. The pressure here is indicative of the pressure in the LEFT ATRIUM since there are no valves separating the two
Systolic murmur
Heard during systole.
During systole, the AV valves should be shut. The semilunar valves should be open.
Murmur - through an insufficient AV valve, or through a stenosised Semilunar
Diastolic murmur
During diastole the Semilunar valves should be shut and the AV valves should be open for filling.
Murmur - through a stenosis of the an AV valve or an insufficient semilunar valve
Physiological splitting of the 2nd heart sound
This is normal; caused by the fact that the ventricle increases in volume due to increased venous return from the negative pressure caused by inhalation. The increase in volume is basically an increase in preload, which results in the slower contraction of the RV compared to the LV, which means the pulmonary valve shuts slightly behind the aortic valve.
Persistent splitting
This is caused by a right bundle branch block (RBBB) which exaggerates the split seen in physiological splitting and the pulmonary valve closes much later than the aortic valve.
the electrical reason contributes to a physiological reason of why RV contracts slower/pulmonary valve shuts later
Inspiration causes exaggeration
Paradoxical splitting
This is caused by a LBBB. The slowed conduction in the LV causes the aortic valve to shut after the pulmonary valve.
However, inspiration causes a RV delay, so the gap b/t the aortic and pulmonary valve closures is REDUCED.
