Valvular dysfunction Flashcards
What is the difference between valve stenosis and incompetence?
Valve Stenosis = Narrowing
– Restriction of flow
– Higher pressure in chamber behind valve
- LV in Aortic Stenosis
- LA in Mitral Stenosis
– Pressure overload
Valve Incompetence = Regurgitation = Leaking
– Blood leaks back into previous chamber
– Heart required to pump greater SV to maintain forward CO
– Greater volume in ventricle
– increase in EDV
– Increased ejection fraction
– Volume overload
- Irreversible LV changes occur about the time symptoms develop in regurgitation
- In Aortic Stenosis symptoms indicate time to intervene and LVH changes usually regress
What is the physiology and feautres of aortic stenosis?
Aortic Stenosis
- Progressive narrowing of aortic valve – Fibrosis, Calcification
- Reduction in Valve Area: Normal >2.5cm2, Severe < 0.7 cm2
- Pressure gradient across valve: Normal 0, Severe >50mm Hg
- “Cresendo - decrescendo” murmur (harsh, rough)
LV Response
- Pressure overload of LV
- Concentric hypertrophy, Walls thicken, less compliant
- Diastolic dysfunction, Increased LVEDP required to fill LV
- Atrial contraction important to fill LV
- LV changes usually reverse after surgery
What is the physiology and feautres of aortic regurgitation?
Aortic Regurgitation
Causes:
• Aortic leaflets damaged
– Endocarditis, Rheumatic Fever
• Aortic root dilated so leaflets don’t close
– Marfan’s Syndrome
– Aortic Dissection
LV response
- Part of each SV leaks back into LV during diastole
- greater SV needed to maintain normal CO
- Volume overload, Increased EDV
- Increased Ejection Fraction (high SV and rapid drop in BP after systole = large PP)
- Normal End Systolic Volume
- Early diastolic murmur (lub dub whoosh)
- Eventual decompensation if prolonged severe aortic regurgitation (irreversible)
What is the physiology and feautres of mitral regurgitation?
Causes:
- Myxomatous degeneration (mitral valve prolapse)
- Ruptured chordae tendinae (flail leaflet)
- Infective Endocarditis
- Myocardial infarct – ruptured papillary muscle
- Rheumatic fever
- Collagen vascular disease
- Cardiomyopathy – change in ventricular shape
LV response:
- Portion of SV ejected into low pressure LA - high pressure gradient throughout systole and same vol. = uniform mumur intensity
- greater SV to maintain normal CO
- Volume overload, Increased EDV
- Increased Ejection Fraction
- Normal End Systolic Volume
- Increased LA volume & pressure -> Atrial Fibrillation
->Thrombus in LA – risk of embolism
- Increased PVP – Pulmonary congestion/oedema -> hypoxia -> increased PAP -> pulmonary hypertension
- If prolonged severe MR, eventual decompensation
What is the physiology and feautres of mitral stenosis?
Mitral Stenosis
Causes:
- Due to previous rheumatic fever esp. in women
- Fibrotic, narrowed mitral valve
LV response
- Pressure gradient across mitral valve
- Reduced filling of the LV
- LA contraction more important
- LV systolic function not affected
- Increased LA pressure and volume ->Atrial Fibrillation -> Thrombus in LA – risk of embolism
- Increased PVP – Pulmonary congestion/oedema
–> Hypoxia
• Increased PAP –> pulmonary hypertension
