Clinical Pathophysiology of Valvular Heart Disease Flashcards
What states of overload do the right and left ventricle handle best?
Right ventricle - Volume overload (would do better with pulmonary valve insufficiency)
Left ventricle - Pressure overload (would do better with aortic stenosis)
What are the two broad causes of valvular stenosis?
- Congenital - narrowing of valve annulus, or supra / subvalvular area
- Acquired / functional - failure to fully open valve / leaflets (i.e. calcific, rheumatic)
What are the causes of valvular regurgitation?
- Intrinsic leaflet abnormalities
- Damage to valve or supporting structures
- Failure for leaflets to coaptation / apposition due to a stretched valve annulus
When will symptoms of severe congenital valvular stenosis begin to show up in a child?
If aortic stenosis is so marked that they rely on a patent ductus arteriosus for delivery of blood to systemic circulation, cyanosis will begin early after its closure.
How can the pressure in the left ventricle be estimated non-invasively in valvular stenosis?
Modified Bernoulli Equation
Pressure will be ~4 v^2, where the velocity can be measured on ultrasound. You are measuring the velocity of the blood coming into the aorta, and determining the LV preassure based on this.
At what threshold value of flow area remaining in stenosis do symptoms begin to appear? What is this value in mitral stenosis?
<50% its normal area (>50% stenosis)
2 cm^2 is critical in mitral stenosis (50% normal)
Describe the pathophysiology of right heart failure from mitral stenosis? Start by saying what will happen to the stroke diagram?
Mitral stenosis -> decreased LV EDP (need greater pressures in LA to fill)
Increased LA pressures -> LA dilatation -> Atrial fibrillation
Increased pressures back up into pulmonary circulation, cause pulmonary edema + exertional dyspnea
Increased pulmonary pressures cause pulmonary artery hypertension and subsequent right heart failure.
How does mitral stenosis predispose you to systemic thromboembolism?
Stenosis -> LA dilatation -> atrial fibrillation -> blood stasis -> mural thrombus formation
Why are the symptoms of mitral stenosis worse during exercise?
Less passive filling of LV during diastole in tachycardia -> need to push more blood through stenotic valve during exercise, leading to increased pressure and atrial dilatation
What are the classic physical exam findings of right heart failure?
Jugular venous distension, hepatomegaly, ankle edema, ascites, pleural effusion
What heart sounds are heard in mitral stenosis alone?
Loud S1
Opening snap during early diastole
Low frequency diastolic rumble (absence of silence)
What heart sounds will indicate pulmonary hypertension with
Loud P2 component of S2
High frequency systolic regurgitation murmur from leaking tricuspid valve
What symptoms will the patient experience due to pulmonary hypertension?
Orthopnea, exertional dyspnea, paroxysmal nocturnal dyspnea, fatigue, exercise intolerance
What can be seen on X-ray with pulmonary hypertension?
Kerley B lines -> due to fluid buildup in the pulmonary capillaries
What can be seen on Echocardiogram with mitral stenosis?
Diastolic doming of mitral valve into the left ventricle (not truly opening up), and left atrial enlargement
Other than Afib and systemic thromboemboli, what other complications can occur due to mitral stenosis?
Results of pulmonary HTN:
1. Hemoptysis, from congestion and leakage in lung
- Pulmonary infections, due to fluid overload
What is the treatment for rheumatic fever mitral stenosis, and generally what is the treatment for all mitral stenosis (medical treatment)?
Rheumatic fever - long-term penicillin prophylaxis
For all: Diuretics -> reduce volume overload, but not too much otherwise you can dangerously drop LV preload
What are the indications for mitral valvotomy and what is it?
Symptoms with highly stenotic valve, pulmonary HTN, systemic thromboemboli, or asymptomatic future pregnant female due to volume increase in pregnancy
Mitral valvotomy = balloon valvotomy, inflate a catheter in the AV junction
What are the common etiologies of aortic stenosis?
Congenital bicuspid aortic valve -> often cause fusion at commissures
Calcific aortic valve disease
Rheumatic heart disease
What will happen to LA pressure in aortic stenosis?
Will increase, since LA pressure = LV filling pressure = LV diastolic pressure
What happens to the stroke work diagram in aortic stenosis?
LV ESV increases due to increased afterload -> decrease in stroke volume. Must be compensated with hypertrophy
What are the symptoms of aortic stenosis?
SAD: syncope, angina, dyspnea on exertion (inability to increase CO any further during exercise)
Late: Pulmonary HTN symptoms due to LA pressure increases.
What will happen to the pulse pressure and pulse in aortic stenosis?
Pulse pressure narrows (opposite of aortic regurgitation)
Pulse is weak and delayed (parvus et tardus)
- > due to less increase in systolic BP (explains narrowed pulse pressure)
- > takes longer for valves to swing open (delayed pulse as compared to heart beat)
What abnormal heart sounds will be associated with aortic stenosis?
- Systolic ejection click - which can go away with worsening stenosis (due to pressure in ventricles finally being high enough to whip the valve open)
- Crescendo-decrescendo systolic murmur - sometimes with palpable thrill
- S4 - due to diastolic dysfunction of atrial contraction
- Paradoxical splitting of S2 -> lengthening of LV ejection time makes A2 happen after P2
What ECG and Echo findings are associated with aortic stenosis?
ECG - LV hypertrophy, T wave inversion due to LV strain
Echo - Commissural fusion, thickened valve leaflet with doming of valve during systole. LV-aortic pressure gradient detectable.
What will a heart catheter tell you in aortic and mitral stenosis?
Aortic: Pressure difference between LV and aorta
Mitral: Pressure difference between LA and LV
How can cancer treatment cause valvular stenosis?
Radiation of the mediastinum is associated with fibrotic changes which can lead to mitral or aortic stenosis
How can hypertrophic cardiomyopathy cause aortic stenosis? What else does it cause?
If obstructive, could be due to systolic anterior motion of mitral valve (i.e. valve swings into LV outflow tract) or due to ventricular septum getting in the way of the LV outflow track
If mitral valve is brought in to LVOT, also causes mitral regurgitation