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
What heart abnormality is associated with Williams syndrome?
Supravalvular aortic stenosis
Should a diuretic be used to treat aortic stenosis?
NO! Need to maintain cardiac output as much as possible with increased LV preload.
-> Maintain hydration
What are the indications for surgical valve replacement in aortic stenosis?
Severe stenosis with <50% EF
Biscuspid aortic valve with aortic root dilatation
Who typically gets balloon valvuloplasty for aortic stenosis? What is the risk?
Noncalcific causes of aortic stenosis -> i.e. rheumatic fever, mediastinal radiation, etc
Risk is causing aortic regurgitation from ripping open valve leaflets
What is the Ross procedure and why is it okay to do?
Putting pulmonary semilunar valve in place of aortic, with a bovine valve in place of pulmonary
-> okay because we don’t care about pulmonary regurgitation (RV can handle volume overload)
How is mitral regurgitation a vicious cycle?
Mitral regurgitation -> increase LA pressure during systole -> becomes dilated, leading to greater LV filling during diastole -> increased preload and LV volume overload -> Eccentric hypertrophy, stretching of mitral annulus -> worsening regurgitation, ultimately compromising CO and causing heart failure
What will happen one the left atrium dilates significantly in mitral regurgitation?
LA loses compliance -> increased left atrial pressure -> pulmonary hypertension
LA dilation also -> atrial fibrillation
What is the most common cause of mitral regurgitation?
Mitral valve prolapse -> a usually benign finding unless it is in the context of an underlying connective tissue disorder
What heart sound findings are associated with mitral regurgitation due to mitral prolapse, and how are they changed with LV preload?
Late systolic murmur associated with midsystolic click
Click and murmur begin later (closer to S2) with increasing LV preload (Chordae tendinae are too long in prolapse. Distention of LV will make them the more appropriate size until some contraction has occurred)
What are some things that increase and decrease preload?
Increase - Squatting (more blood back to heart), bradycardia, propanolol
Decrease - Valsalva maneuver (inspiration decreases blood delivery to LV), standing, tachycardia
What is atrioventricular canal?
Congenital heart disease as a result of embryologic arrest, can take many forms
Complete, incomplete, balanced, or unbalanced
Balanced refers to whether left size or right side of heart are proportinoal in size
What is cleft mitral valve?
A cause of mitral regurgitation due to a cleft in a mitral valve leaflet
How can rheumatic heart disease cause mitral regurgitation?
Leaflets become retracted, deformed, with shortening / contraction / fusion of chordae tendinae
-> generally leads to stenosis with regurgitation
How can MI lead to mitral regurgitation?
Ischemia to papillary muscle -> malfunction of valve apparatus
How does acute vs chronic presentation of mitral regurgitation differ?
Acute - no time to compensate, symptoms of pulmonary edema
Chronic - often asymptomatic, but if severe will cause pulmonary edema, exertional dyspnea, orthopnea, etc (similar to Mitral Stenosis)
What can be seen on the chest with well-compensated mitral regurgitation?
Hyperdynamic precordium (chest moves a ton)
What murmur is generally associated with mitral regurgitation (not just mitral prolapse). Include relevant characteristics.
High frequency systolic regurgitant murmur heart at cardiac apex
Radiates to axilla
- > intensity increased with greater afterload (exercise)
- > decreased with Valsalva to decrease preload
Why might a diastolic rumble be present with mitral regurgitation?
Huge volume of blood goes from LA to LV
-> the normal valvular annulus seems “relatively” stenosed.
What will EKG and Echo show for mitral regurgitation?
EKG - LA enlargement, with atrial fibrillation
Echo - LA enlargement, hyperdynamic LV, and the MECHANISM of mitral regurgitation (whatever that may be)
What are some acute causes of mitral regurgitation?
Papillary muscle rupture, chordal rupture w/flail leaflet, trauma, ENDOCARDITIS
What is the most important thing to control when treating mitral regurgitation?
Afterload -> do not want to make systemic system difficult to push against
- > ACE Inhibitors
- > diuretics for volume overload, particularly if causing pulmonary congestion
What is the maze procedure?
Procedure often used in mitral regurgitation / stenosis which cause LA dilatation and atrial fibirillation
-> create some scar tissue to interrupt the Afib re-entry circuit
Why are the coronary arteries particularly at risk for being insufficient in Aortic regurgitation?
The aortic valve maintains diastolic blood pressure throughout the cardiac cycle
-> low diastolic blood pressures = poor perfusion of coronary arteries
What will happen to the stroke volume diagram with aortic regurgitation? Pulse pressure?
Much higher end diastolic volume -> greater stroke volume
Pulse pressure will be very wide (opposite of aortic stenosis)
What are some of the causes of aortic regurgitation?
Valvular - damaged leaflets
Aortic root dilatation - Stretched annulus with poor coaptation of normal leaflets
What is the pathophys of right-heart failure in aortic regurgitation?
Aortic regurgitation = increased LVEDP due to volume overload = increased radius of ventricle = eccentric hypertrophy to increase compliance = LVEDP falls, and mitral valve annulus dilates, leading to mitral insufficiency = LA dilatation and LA hypertension -> pulmonary HTN and RV failure.
What are the acute and chronic symptoms of aortic regurgitation?
Acute - Dyspnea, pulmonary edema due to fluid backup from increased diastolic pressure of LA
Chronic - Stretched muscle fibers are inefficient -> angina and dyspnea on exertion (Reduced cardiac output)
What are the key physical exam findings of aortic regurgitation?
Wide pulse pressure
Hyperdynamic precordium (like mitral regurgitation)
Diastolic decrescendo (high frequency on left sternal border)
Bobbing head
What causes an “Austin-Flint” murmur?
Diastolic rumble -> due to diastolic jet from aortic regurgitation blocking the opening of the mitral valve
-> impaired opening of mitral valve
What will the EKG and Echo show for aortic regurgitation?
EKG - Left axis deviation, LV hypertrophy, LV strain pattern (ST depression and T wave inversion in I, aVL, and V5/V6)
Echo: Mechanism of AR, LV size, and LV ejection fraction
What are common mechanisms of aortic regurgitation?
- Aortic valve morphological abnormalities
- Subaortic membrane -> damages valve by causing tubulent flow in outflow tract
- Small VSD causes a left -> right shunt which causes valve to prolapse to follow stream
Give a congenital cause of aortic regurgitation which can also cause stenosis.
Biscuspid aortic valve -> may also leak
What activities should people with aortic regurgitation avoid, and what is the medical treatment?
Isometric exercises -> i.e. weightlifting, requires intense increases in SBP
Treatment:
Diuretics, and afterload reduction if hypertension is present
What are the indications for surgery in aortic regurgiation?
Patient has symptoms, LV function becomes depressed (<50%), or LV dilatation is significant
Why might you choose to have a bioprosthetic valve instead of a mechanical valve if you are a young woman?
If you intend to get pregnant, you need to be on warfarin with a mechanical valve, which is a teratogen!
What are the major and minor criteria for acute rheumatic fever?
Major: JONES
Minor: Fever, Labs: increased ESR, increased CRP, arthralgias (if no J, aka just pain no inflammation), and prolonged PR interval
What are the criteria needed in order to diagnosed acute rheumatic fever?
3 options
1. Two major criteria or 2. One major and two minor or 3. Sydenham's chorea alone
What are the heart changes which will acute in rheumatic fever acutely and chronically? What valves are affected?
Mitral > aortic valve affected
Acute - regurgitant disease
Chronic - Stenotic disease
Pericardial effusion may lead to pericarditis
Where do subcutaneous nodules tend to present?
On extensor surfaces. They are hard, painless, and nonpruritic
What antibodies provide evidence for past Group A Strep infection?
Antistreptolysin O (ASO) or anti-DNAse B titers
What are the most common cardiac findings in Marfan syndrome?
Mitral valve prolapse and aortic root dilatation, leading to the following abnormalities
- Mitral valve prolapse
- Mitral regurgitation
- Aortic regurgitation
What is the medical treatment for cardiac complications of Marfan syndrome?
Competitive sports restrictions
- Beta-blockers
- ACE inhibitors
- Angiotensin receptor blockers
-> volume control
What is the surgical treatment for Marfan?
Surgery for significant aortic root dilatation or in the presence of heart failure due to mitral regurgitation
