51 - Cardiac Valve Dysfunction Flashcards
Proportion of heartbeat that is systole and is diastole
~1/3 is systole, ~2/3 is diastole (diastole is longer)
Effect of valve stenosis 1) 2) 3)
1) Valve doesn’t open fully, restricting flow. 2) Higher pressure in chamber behind valve (EG: LV in aortic stenosis, LA in bicuspid stenosis) 3) Pressure overload
Valve incompetence
Valve leaking/regurgitation. Where valve doesn’t close properly, causing leak of blood back.
Effect of valve incompetence
Heart required to increase stroke volume to maintain forward cardiac output. Increased volume in ventricle increased EDV. This increases ejection fraction and preload.
What used to be most common cause of valve disease?
Rheumatic fever
Current most common cause of valve disease
Degenerative conditions
When do valve lesions become symptomatic
When they are quite severe. Mild and moderate lesions are asymptomatic
When do symptoms develop in valve regurgitation?
Late stage. Occur when irreversible LV changes occur (ventricular enlargement, decompensation).
When do symptoms present in aortic stenosis?
Before permanent LV changes
How is valvular heart disease assessed? 1) 2) 3) 4)
1) History (especially shortness of breath, which presents in late stage, is poo prognosis) 2) Examination (murmur, pulse) 3) ECG 4) Echocardiography (most important test)
Types of prosthetic valves 1) 2) 3) 4)
1) Mechanical valve 2) Bioprosthetic valve 3) Repaired mitral valve 4) Stent aortic valve
Procedure than can fix a stenosed valve
Balloon valvotomy (insert balloon catheter into valve, inflate to break up stenosis).
Normal aortic valve area
2.5cm^2
Severe aortic stenosis valve area
Under 0.7cm^2
Normal pressure gradient across aortic valve
0mmHg
Severe pressure gradient across a stenosed aortic valve
Over 50mmHg
*Appearance of a Wigger’s diagram of a stenosed aortic valve
Note exaggerated LV systolic pressure
Left ventricular response to aortic stenosis 1) 2) 3) 4) 5)
1) Concentric hypertrophy from pressure overload 2) Less compliant walls, as thicker 3) Diastolic dysfunction 4) Increased LVEDP required to fill LV 5) Atrial contraction becomes important to fill LV
LV response to surgery for aortic stenosis
Often returns from concentrically-hypertrophied to normal
What causes systolic murmurs?
Problems with either aortic or pulmonary valve
Murmur sound of aortic stenosis
Crescendo-decrescendo. Pressure gradient rises and falls quickly during systole.
Effects of aortic regurgitation 1) 2) 3) 4) 5)
1) To maintain normal cardiac output, LV needs to pump greater volume with each beat 2) Volume overload 3) Increased end diastolic volume 4) Increased ejection fraction 5) Normal end systolic volume
*How does a Wigger diagram of aortic regurgitation appear?
Exaggerated LV systolic pressure and aortic pressure
When do symptoms of aortic regurgitation present?
Often when irreversible decompensation occurs
Effects of untreated aortic regurgitation 1) 2) 3)
1) LV diastolic volume increases a lot 2) LV function decreases 3) LV systolic volume increases
Causes of mitral regurgitation 1) 2) 3) 4) 5) 6) 7)
1) Myxomatous degeneration (mitral valve prolapse) 2) Ruptured chordae tendinae (flail leaflet) 3) Infective endocarditis 4) Myocardial infarct (can rupture papillary muscle) 5) Rheumatic fever 6) Collagen vascular disease 7) Cardiomyopathy (change in ventricle shape)
Effects of mitral regurgitation 1) 2) 3) 4) 5) 6)
1) To maintain CO, LV needs greater stroke volume 2) Volume overload 3) Increased end diastolic volume 4) Increased ejection fraction 5) Normal end systolic volume 6) Increased left atrial volume and pressure (same as with aortic regurgitation, except for left atrial change)
Effects of decompensation from mitral regurgitation 1) 2)
1) Increase in LV diastolic and systolic volume (diastolic is more marked) 2) Reduced ejection fraction
When do symptoms of mitral valve regurgitation appear?
When decompensation occurs. Changes irreversible
Mitral systolic murmur 1) 2) 3)
1) From regurgitation 2) Pressure gradient between LA and LV appears 3) Pansystolic murmur, not crescendo-decrescendo like aortic stenosis murmur.
Common cause of mitral stenosis
Rheumatic fever in women
Effect of mitral stenosis 1) 2) 3) 4)
1) Reduced LV filling 2) LA contraction becomes more important in filling LV 3) LV systolic function not affected 4) Can lead to pulmonary artery hypertension
*Appearance of a Wigger’s diagram with mitral stenosis
Elevated left atrial pressure
How well is mitral stenosis tolerated?
Well, if mild to moderate
Interventions for stenoses 1) 2)
1) Valvotomy 2) Valve replacement
Possible causes of valve prolapse
Long chordae tendinae or valve leaflets
