Valvular Heart Disease Flashcards

1
Q

Pressure vs time graph: atrial contraction

A
  • Raises left atrial and left ventricular pressure
  • “a” wave on pressure tracings, LV volume curve
  • “A” wave on mitral valve flow
  • S4 occurs at or just after peak flow velocity
  • Associated with cardiac diseases reducing LV compliance or attenuate LV filling during early diastole
  • Get increased amount of filling with atrial contraction → increased amount energy expended → sound
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2
Q

Pressure vs time graph: Isovolumic contraction

A
  • LV pressure rises
  • Mitral valve forced shut after LV pressure > LA pressure
  • Closure of mitral valve = “C” wave on LA tracing
  • Responsible for S1
  • When LV pressure > aortic pressure → open aortic valve (end of isovolumic contraction)
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3
Q

Pressure vs time graph: ejection

A
  • Aortic and ventricular pressures track together
  • Left atrium is filling
  • Initial decline of pressure (“x”) during relaxation
  • Slow rise in pressure
  • Peaks at “V” wave near end-systole
  • LV pressure falls
  • When LV Pressure < atrial pressure → aortic valve closes
  • S2
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4
Q

Pressure vs time graph: diastolic rapid filling

A
  • LV actively relaxes
  • LV pressure < LA pressure → creates suction
  • Result: rapid blood flow into LV; decreases pressure in LA (“y”)
  • Rapid increase in LV volume (70% filling)
  • “E” wave in mitral valve flow
  • S3 due to increased volume of blood flow during rapid filling from high output state or volume overload; or due to conditions that increase LA V-wave pressure
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5
Q

Pressure vs time graph: Diastasis

A

Passive filling
• LA and LV pressures in equilibrium
• Minimal LV filling
• Length of diastasis depends on heart rate

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6
Q

Causes of heart murmur production

A

o Turbulent flow
o Abnormal vortices of flow
o Audible vibrations
o High pressure gradient = high flow velocity → high pitched murmur
o Low pressure gradient = low flow velocity → low pitched murmur

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7
Q

Types of heart murmurs

A

Systolic murmurs
1) Mid-systolic ejection murmur
• Produced by flow leaving ventricle
• Begins after LV Pressure > aortic pressure
• Increases intensity as ejection velocity increases
• Diminishes before end of systole
2) Holosystolic regurgitant murmur
• From backward flow from high to low pressure chamber
• Pressure gradient maintained throughout systole
• Constant intensity throughout
• Ex. Mitral regurgitation

Diastolic murmurs 
1) Regurgitant murmur
•	Backward flow across incompetent semilunar valve 
•	Decrescendo shape
o	Pressure gradually drops in vessels during diastole 
o	Reduces pressure gradient 
•	Ex. Aortic insufficiency 
2) Filling murmur
•	Obstruction of filling of ventricles 
•	Low pitched
•	Dual component: loudest when filling velocity is highest (early diastole and atrial systole)
•	Ex. Mitral stenosis
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8
Q

Causes of Aortic Valve insufficiency (aortic regurgitation)

A

Primary cusp abnormality
• Rheumatic → fibrosis and commissural fusion
• Degenerative
• Endocarditis → direct leaflet destruction
• Congential (bicuspid)
Primary aortic root abnormality
• Ascending aortic aneurysm (dilates valve)
• Aortic dissection (acute problem)

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9
Q

Pathophysiology of Aortic Valve insufficiency (aortic regurgitation)

A

o State of volume overload
o Increased afterload and preload → increased wall stress end- systole and end-diastole
o LV can’t compensate with increased ventricular ejection because afterload doesn’t fall
o Result: Frank-Starling Mechansim:
• LV chamber enlargement
• Filling curve shift to the right and downward → improved ventricle filling due to increased chamber compliance
• Initiated by mechanical stretch signal:
• Matrix metalloproteinases dissolve fibrous skeleton and reorient
• Myocytes elongate = eccentric hypertrophy (increase number of contractile units in series)

-Chronic compensated: systolic and diastolic wall stress about normal
-Chronic decompensated:
• LV volume increases
• Increased fibrosis → less compliance
• Systolic performance declines → heart failure

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10
Q

Hemodynamics of Acute Aortic insufficiency

A
  • Sudden volume overload in LV
  • Limited ability to dilate to accommodate → total stroke volume rises only a little and net forward stroke volume falls
  • HR increases to compensate for decreased SV
  • Increased LV diastolic pressure, causes increase in LA pressure
  • End-systole: central aortic pressure falls rapidly
  • Due to aortic regurgitation
  • LV pressure falls to zero, but fills rapidly
  • Combined flow from LA and aortic insufficiency
  • Rise in LV pressure
  • Reaches equilibrium with LA before end-diastole (c)
  • Forces mitral valve shut as LV pressure > LA
  • No further blood flow across mitral valve
  • LA does not empty completely → increase in pressure as blood returns from lungs
  • LA contraction against closed mitral valve
  • No effective forward flow during atrial systole
  • No flow until next diastole
  • Murmur
  • High-pitched decrescendo (g)
  • Begins end-systole, rapidly declines to nothing
  • Amplitude proportional to pressure gradient
  • Also, a systolic ejection murmur (h) from turbulent flow across aortic valve
  • Acute treatment: surgical correction
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11
Q

Hemodynamics of Chronic Aortic insufficiency

A
  • Gradual development allows accommodation and LV remodeling
  • Large chamber with low diastolic pressures
  • Normal heart rate
  • Near normal effective CO
  • Near normal net forward stroke volume
  • Aortic pressure declines from end-systole to end-diastole at greater rate than normal
  • But no equilibrium between aorta and LV occurs
  • LV systolic pressure is elevated from large stroke volume
  • LV diastole pressure near zero
  • LA pressure near normal
  • Mitral valve flow normal
  • Very large pulse pressure (aorta pressure rises and fall rapidly)
  • Murmur
  • Throughout diastole
  • Decrescendo-type
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12
Q

Hemodynamics of Chronic Decompensated Aortic insufficiency

A
  • Heart larger but decreased systolic function
  • Increased end systolic volume
  • Similar stroke volume but elevated diastolic filling pressures
  • Symptomatic dyspnea
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13
Q

Progression of aortic insufficiency

A

o Long period = asymptomatic (chronic compensated)
o If LV function is normal, then low (1-2%/year) conversion to symptomatic limitation/LV dysfunction
o If LV dysfunction (LV EF 25% per year
o Once symptoms: mortality rate is >10% per year

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14
Q

Treatment of aortic insufficiency

A

Prevent symptoms with exercise:
o Induces vasodilation → reduces ejection impedance
o Increases heart rate → reduces diastolic time so less time for insufficiency to occur
Treatment BEFORE symptoms arrive
o Optimally preserves LV function
o Monitor LV size and insufficiency severity by echocardiography
o Usually = valve replacement, sometimes repair
o Successful surgery → regression of hypertrophy

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15
Q

Causes of Aortic stenosis

A

o Calcific degeneration of valve: nodules of Ca2+ → stiffening
o Rheumatic heart disease: fusion of leaflets
o Congenital heart disease (bicuspid valve)
• Asymmetric leaflets
• Increase stress and deterioration → calcification

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16
Q

Pathophysiology of Aortic stenosis

A

o Mechanical shear stress (most important)
o Genetic predisposition
o Injury-inflammation cycles:
• More severe response in those with lipid abnormalities or coronary artery disease risk factors
• Atherosclerosis (but no evidence of benefits from statins)
• Multiple pathways for production of Ca2+ (ex. Osteoblasts)

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17
Q

Progression of Aortic stenosis

A

Symptoms develop when about 25-33% of normal opening

Normal:
valve area of 3.5-4.0 cm2
mean gradient: 0 mmHg

Mild:
valve area of 1.5-2.0 cm2
mean gradient: 40
symptoms: angina, dyspnea, and exertional syncope; most symptomatic

Severe:
valve area of 50
symptoms: angina, dyspnea, and exertional syncope; most symptomatic unless sedentary

18
Q

Symptoms of aortic stenosis

A
Exertional angina
•	Subendocardial ischemia
•	Increase in O2 demand due to:
•	LV hypertrophy
•	Increase in systolic pressure
•	Prolongation of ejection time
•	Reduced perfusion from suboptimal capillary structure and elevated diastolic pressures 
Exertional syncope
•	Inadequate rise in CO → underfilling of vasculature
•	Bezold-Jarisch reflex
•	Due to high pressures in LV
•	Results in decreased contractility and HR, further vasodilation 
Dyspnea on exertion 
•	Diastolic dysfunction
•	Systolic failure
19
Q

Treatment of aortic stenosis

A

Medical Treatment
o Avoid heavy exertion and competitive sports if moderate or greater AS severity
o Maintain sinus rhythm
o Alert patient for symptoms to watch out for
o Follow up echocardiogram in asymptomatic patients
• Mild: every 3-5 years
• Moderate: every 1-2 years
• Severe: every year
o Symptomatic patients → surgery

Surgical treatments
o ALL symptomatic patients should be considered
o Best outcome: with normal LV function
o Asymptomatic patients, consider surgery if:
• During other CV surgery
• With symptoms and hypotension during exercise stress test
• With LV dysfunction (LV EF <50%)
• Marked LV hypertrophy
• Critical reduction in valve area

20
Q

Hemodynamics of Aortic stenosis (as increase in severity)

A

Systolic pressure drop (shaded region)
• Area of region = mean pressure across the aortic valve
• Increases as stenosis becomes more severe
• Shape changes (aortic pressure rate of increase rises more slowly)
Murmur
• Diamond shaped ejection murmur
• Mild stenosis: peaks in mid-systole
• More severe: prolonged (peaks later in systole)
• Pitch usually increases as well
Second heart sound
• Calcification of valve → stiffens leaflets, less motion → decreased sound intensity

21
Q

Compensatory LV changes with aortic stenosis

A

o Pressure overload → concentric LV hypertrophy
o Myocytes increase number of contractile units in parallel
• Thicker, more powerful cells
o Maintains near normal end-systolic wall stress
o Energy efficiency is improved (reduced Vmax, lower dP/dt)
o Downside:
• Coronary flow is impaired
• Decreased active relaxation rate
• Decreased extent of relaxation
• Filling pressures go up

22
Q

Compensatory LA changes with aortic stenosis

A

o Elevated LV pressures → elevates LA pressures → LA hypertrophy
o Atrial contraction more powerful → higher velocity → S4

23
Q

Types of dyspnea

A

• Exertional

• Orthopnea
o Develops in recumbent position; relieved if elevate head
o Due to heart’s inability to handle fluid that pooled in lower extremities and now gets returned back to central circulation

• Paroxysmal nocturna
o Same mechanism as orthopnea
o More severe and prolonged

• Pulmonary edema
o Most severe
o Flooding of alveoli

24
Q

Describe the sequence of events that take place in the alveoli as left atrial pressure rises

A

• LA pressure rises due to:
o Aortic stenosis → diastolic myocardium abnormalities
o Aortic insufficiency → volume overload
o Mitral valve disease → stenotic obstruction of forward flow or leaflet insufficiency
• Results in increased pulmonary venous pressure
• Increases pulmonary capillary pressure → increase in interstitial lung fluid (capillary leakage and increased total volume in lungs)
• Increased lung stiffness
• Closure of some dependent airways
• Result: reduced tidal volume and increased effort
• Need more breaths/minute at higher effort level → SOB
• Eventually: alveoli collapse and flood → no gas exchange

25
Common causes of mitral stenosis
• Common cause: rheumatic fever | o Fusion of mitral apparatus
26
Pathophysiology of mitral stenosis
o LV inflow obstruction Symptoms: • Dyspnea from high filling pressures • Hemoptysis: hemorrhages in pulmonary vasculature from increased pressures • Fatigue from decreased CO LA is enlarged • Atrial fibrillation → sluggish blood flow • Thrombus formation with embolism RV and RA may become enlarged and dysfunctional later in disease
27
Hemodynamics of mitral stenosis
o Diastolic pressure gradient from reduced valve opening o LV pressure normal o Aortic pressure normal o LA pressure continually elevated o Results in severe pulmonary HT • With increased pulmonary vascular resistance → RV hypertrophy Heart sounds 1) Increased amplitude of S1 • When stenotic but pliable valve • Snaps shut → increase in sound amplitude • With calcification → decreased mobility → decreased amplitude 2) Opening snap • Early in diastole • Opening of valve = rapid filling stretches leaflets out • Snap occurs when taunt leaflets reach peak of opening • Calcification decreases snap 3) Diastolic rumble • Low-pitched (relatively small gradient) • Two part murmur: • Mid-diastolic: initial part; occurs after opening snap (diastolic flows greatest) • Decrease in murmur sound in mid-diastole (lower flow gradient) • Late diastolic/ pre-systolic part: due to atrial contraction, only occurs with sinus rhythm • ***Murmur amplitude is proportional to CO
28
Treatments of mitral stenosis
``` o Balloon valvuloplasty o Open surgical commisuratomy o Mitral valve replacement o Anticoagulation o Prevention of pulmonary HT ```
29
Progression of mitral stenosis
``` Minimal: Valve area: > 2.5 cm2 Mean gradient: 0 mmHg Peak PA pressure: WNL mmHg Symptoms: none ``` ``` Mild: Valve area: 1.5-2.5 cm2 Mean gradient: 10 mmHg Peak PA pressure: >50 mmHg Symptoms: dyspnea with minimal exertion, orthopnea, paroxysmal nocutrnal dyspnea, fatigue ``` Severe + pulmonary HT: Valve area: 10 mmHg Peak PA pressure: >70 mmHg Symptoms: decreased dyspnea, increased fatigue, increased fluid retention
30
Causes of Mitral Insufficiency
``` o Leaflet substance loss (ex. Due to rheumatic heart disease) o Excess substance • Too large → mitral valve prolapse with myxomatous degeneration o Loss of annular contraction o Leaflet destruction o Chordal rupture (flail valve) o Papillary muscle dysfunction o Annular stretch from LA enlargement ```
31
Pathophysiology of Mitral Insufficiency
o State of increased preload and reduced afterload for LV o Dilation (eccentric remodeling and hypertrophy) → Increased LV volume at end diastole o More complete EF → Decreased volume at end systole o Supranormal LV function when well compensated o Deterioration → progressive increases in both end diastolic volume and end systolic volume
32
Hemodynamics of Acute Mitral Insufficiency
(ruptured chordae tendinea or papillary muscle, or endocarditis) • Small LA can’t accept large volume of blood → increase in LA pressure (v wave) • LA pressure lowest during isovolumic relaxation (p) • LA pressure not at zero = preserves LA/LV pressure gradient in diastole • LV rapid filling → S3 • Fast equilibrium of LA and LV; pressures rise further after atrial contraction (q) • End systolic volume is reduced in compensation to increased contractility • Murmur: systolic, peaks early in systole, diminishes before end-systole
33
Hemodynamics of Chronic Mitral Insufficiency
* LV is enlarged, more compliant * Diastolic pressures near normal * Sinus rhythm * Prominent a wave from atrial contraction (s) * Systolic atrial pressures increase (t) from regurgitation * Produces large gradient between LA and LV * Causes rapid filling of LV * Prominent S3 * Rapid equilibrium occurs in mid-diastole * Murmur: holosystolic * Constant amplitude since gradient is maintained
34
Hemodynamics of Chronic Decompensated Mitral Insufficiency
* Weakened LV can’t contract as well * End-systolic volume increases * Forward stroke volume is reduced * Increased regurgitant volume present * Normal EF from favorable loading conditions * But decreased LV function * LA and LV pressures high
35
Pulmonic stenosis
Cause: o Congenital (almost all) o Rheumatic disease or carcinoid syndrome Pathophysiology: o Pressure overload o In utero: stimulates myocyte hypertrophy and hyperplasia • Allows longer/better compensation • Valve grows proportionately with body = degree of stenosis remains stable • Calcification is rare o Acquired: poorly tolerated, high wall stress Symptoms: o Fatigue from reduced CO o Dyspnea with exertion • Poor CO → poor perfusion of chest muscles → lactic acidosis → dyspnea Treatment o Patients with moderate or severe gradients (>50 mmHg) o Balloon valvuloplasty is procedure of choice o Alternative: surgery
36
Pulmonic valve insufficiency
Causes: o Usually with other congenital abnormalities or secondary to balloon valvuloplasty or surgery o Commonly from dilation of pulmonary artery Pathophysiology: o Isolated pulmonic insufficiency rare o Usually not a significant problem because pulmonary system at low pressures o Likely makes RV dysfunction progress faster if occurs with existing pathology
37
Tricuspid Stenosis
Causes: o Almost all acquired from rheumatic valve disease o Alternatively: Carcinoid disease Pathophysiology: o Similar to mitral stenosis but smaller pressure gradient o Reduces CO response to exercise o If severe: reduces CO at rest and increases RA pressure • Venous congestion • Fluid retention → edema and fatigue o If untreated → progressive fatigue and symptoms of low CO • Progressive fluid retention • Liver congestion • Edema • Eventually → cardiac cachexia Treatment o Valvular commissurotomy o Valve replacement
38
Tricuspid insufficiency
``` Causes: o Most commonly from annular enlargement and RV dysfunction o Trauma o Carcinoid and rheumatic disease o Congenital causes ``` Pathophysiology If mild to moderate: • Well tolerated for decades If severe: • Changes similar to chronic mitral insufficiency • RA and RV enlargement • Increased central venous pressure • Eventually → RV failure • Well tolerated if normal RV systolic pressures • If pulmonary HT, RV fails at faster rate Symptoms o Fatigue o Fluid retention Treatment o Valve repair o Sometimes valve replacement
39
Explain the effect of infective endocarditis on valve function, signs of endocarditis and principles of prevention as defined by national guidelines
Pathophysiology o Diseased valve with disrupted endothelial surface o Sterile fibrin platelets thrombus forms on valve (vegetation and endothelial damage) o Valve infected • Local tissue destruction → valve regurgitation, abscess, pericarditis, fistula formation • Embolic events → cerebral, systemic, pulmonary • Immune complexes → arthritis, nephritis ``` Typical endocarditis organisms o Strep viridans o Strep bovis o Strep faecalis o Other strep o Staph coagulase + and – o Gram negative, fungal and culture negative ``` Diagnose: using Duke Criteria (because non-specific symptoms of fever, fatigue, heart failure) o Blood cultures o Evidence of valve involvement (new regurgitation, echo) o Predisposition (ex. Certain cardiac conditions or injection drug-use) Treatment o Some cured by antibiotics with modest valve damage o Others need valve surgery
40
AV Repair/Replacement
Repair: • Annular dilation repair (associated with aortic aneurysm) • Bicuspid valve without calcium → make seal • Perforation (typically from endocarditis) → patch leak Replace Valve: Porcine valve o Aortic valve from pig mounted on stent of polypropylene or wire o Non-thrombogenic, no long-term anticoagulation o Poor hemodynamics, progressive calcification and tissue failure Stentless Porcine Valves o Intact porcine valve or entire aortic root o Better hemodynamics Homografts o Cyropreserved human aortic roots o Procedure of choice for endocarditis complicated by abscess o Technically challenging, hard to judge durability Autografts o Replaces aortic valve with patient’s own pulmonic valve; inserts bioprosthesis for pulmonic o Long and difficult operation o Long-term = degeneration Mechanic valves o Both single and double leaflet types o Double leaflet typically have better flow profile • St. Jude = most commonly implanted mechanical valve o Excellent durability o Risk of thrombosis → must take warfarin • Pathologic processes of late failure of tissue-derived valves: o Fibrous thickening of leaflets o Tissue overgrowth with leaflet retraction o Collagen disruption o Leaflet tears o Leaflet calcification o Infection *** degeneration = greatest cause of failure for bio valves ***tissue overgrowth and thrombosis = for mechanical valves