Heart Valve

Pathophysiology

There are 2 types of valves in the heart:

1. Atrioventricular

(mitral and tricuspid valves)

2. Semilunar

(aortic and pulmonic valves)

All valves in the heart are unidirectional, unless they are diseased or dsyfunctional.

If valves become narrow (stenotic) or allow blood to flow past when the valves should be closed (regurgitation), the work of the heart will increase.

Atioventricular

Valves

(AV Valves)

- the tricuspid and mitral valves

- these valves allow blood to flow from the atria in to the ventricles during atrial contraction and ventricular diastole.

- has two large leaflets that are not quite equal in size. 

- when the mitral valve is open, the valve, chordae tendinease , and papillary muscle look like a funnel

- mitral valve is most commonly involved in clinical conditions of valvular dsyfunction - mitral regurgitation is the most common

- clinically, mitral regurgitation may be insignificant or represent a life-threatening situation depending on how long it has been going on.

Semilunar

Valves

-the aortic and pulmonary valves

-each has 3 symmetrical valves cusps to provide for complete opening without stretching of the valve.

Pulmonary

Valve

-one of the semilunar valves

-located between the R. ventricle and the pulmonary artery

Aortic

Valve

- the other semilunar valve

- located between the L. ventricle and the aorta

- in the majority of people, the aortic valve has 3 leaflets (some people have a congenital bicuspid valve)

- people with this congential defect may be more susceptible to endocarditis and requir them to have premature aortic valve replacement

Physical Assessment

of

Cardiac Valves

-cardiac ausculatation is an important component of the cardiovascular assessment      

-begin with the diaphragm from the apex (mitral valve), move next to the second left intercostal space (pulmonic valve), then to the second right intercostal space (aortic valve), then to the mind precordium and xiphoid region (tricuspid valve)

-Switch to the bell of the stethoscope and listen to the apex and xiphoid areas again for the 3rd and 4th heart sounds

The Cardiac Cycle

S1

The Cardiac Cycle

S2

-produced by the closure of the aortic (A2) and the pulmonic (P2) valves

-signals the beginning of diastole

The Cardiac Cycle

S3

-produced by the turbulence with the ventricle during early diastole

- may be physiologic in high-output states such as anemia, fever, or infections

The Cardiac Cycle

S4

Systolic

Murmurs

- Systolic murmurs start either with S1 (during isovolumic contraction) or just after S1 (during the ejection period)

- may cover part of systole or all of systole

Mitral Valve

Regurgitation

- causes a typical ejection murmur

- may cover part or systole or all of systole

Diagnostic

Tests

for

Valvular Dysfunctions

- Echocardiogram

- Chest X-Ray

- Electrocardiogram (ECG)

Echocardiogram

- uses ultrasound waves to record the movement of the structures of the heart

- provides information about:

1. valvular structure and motion

2. cardiac chamber size and contents

3. ventricular muscle and septal motion and thickness

4. pericardial sac

5. ascending aorta

6. Ejection Fraction (EF) - percentage of end-diatolic blood volume that is ejected during systole

client has a history of

rheumatic heart disease

Chest

X-Ray

- see size of heart

- DCM

Electrocardiogram

(ECG)

Mitral

Regurgitation

- as the left ventricle contracts, blood is not only ejected into the aorta but also back up into the L. atrium.  This causes L. atrial volume and pressure to increase during ventricular systole

- the afterload on the ventricle is reduced so that end systolic volume can increase if the heart also goes into systolic failure

- there is no true isovolumetric relaxation because as the ventricle begins to relax, the mirtral valve is never closed completely so blood flows back into the L. atrium as long as the intraventricular pressure is greater than L. atrial pressure

- During diastole, the elevated pressure within the L. atrium is transmitted to the L. ventricle during filling so that L. ventricular end-diastolic volume increases

- this would cause wall stress (afterload) to increase if tiw ere not for the reduced outflow resistance that tends to decrease afterload during ejection

- the increased ventricular stroke volume in this case includes the volume of blood ejected into the aorta as well as the volume ejected back into the L. atrium

- these changes just described do not include cardiac and systemic compensatory mechanisms that attempt to mainatin cardiac output and arterial pressure

- blood backflows into the respective atrial chamber during systole (between S1 and S2).  The backward flow results in a holosystolic murmur