Cardiac Valve Disorders

Preload

volume of blood filling the ventricle before contraction

stretch of heart muscle fibers at end diastole

determines how much the heart muscle is stretched before pumping

increased preload raises the work of the heart by increasing the volume it must eject

Afterload

resistance the ventricle must overcome to push blood out during systole

depends on arterial blood pressure and vessel resistance

higher afterload increases the work of the heart by making pumping more difficult

S1 Lub

occurs at the start of systole

caused by the closure of AV valves

ventricular pressure rises → AV shuts

valve closure causes surrounding tissue to vibrate → creates lub sound

S2 Dub

occurs at the end of systole

caused by closure of semilunar valves

ventricular pressure falls → semilunar shuts

closure causes vibration → creates dub sound

AV Valves

right → tricuspid valve

left → mitral valve

Semilunar Valves

right → pulmonic valve

left → aortic valve

Physiological Split

aortic valve closes slightly before the pulmonic valve

sometimes can hear two distinct sounds (especially during inspiration)

Aortic Valve

2nd intercostal space

right sternal border

Pulmonic Valve

2nd intercostal space

left sternal border

Tricuspid Valve

5th intercostal space

left sternal border

Mitral Valve

5th intercostal space

midclavicular line (apex)

Heart Murmurs

extra heart sounds caused by turbulent blood flow

usually heard with a stethoscope during the cardiac cycle

most often due to valve problems (stenosis or regurgitation)

classified by timing → systolic or diastolic

Stenosis

valve doesn’t open fully

blood flow is blocked or narrowed

heart has to work harder to push blood through

ex: aortic type with narrowed aortic valve

Regurgitation

also called insufficiency, valve doesn’t close fully

blood leaks backward

leads to volume overload in the chamber behind the valve

ex: mitral type where blood leaks back into the left atrium

Systolic Murmurs

when the heart contracts

aortic stenosis (left) → narrowed aortic artery, blood struggles to exit left ventricles

mitral regurgitation (left) → leaky mitral valve, blood flows backward into the left atrium

pulmonic stenosis (right) → narrowed pulmonic valve, blood has trouble leaving the right ventricle

tricuspid regurgitation (right) → leaky tricuspid valve, blood flows backward into the right atrium

Diastolic Murmurs

when the heart relaxes and fills

aortic regurgitation (left) → leaky aortic valve, blood leaks back into left ventricle

mitral stenosis (left) → narrow mitral valve, blood has trouble leaving the left ventricle

pulmonic regurgitation (right) → leaky pulmonic valve, blood leaks back into the right ventricle

tricuspid stenosis (right) → narrow tricuspid valve, blood has trouble entering the right ventricle

Valve Disease Causes

calcific degeneration

myxomatous degeneration

coronary artery disease (CAD)

congenital defects

Calcific Degeneration

calcium builds up on the valve making it stiff

most common cause of aortic stenosis in older adults

caused by aging, wear and tear, and chronic inflammation

valve cells may behave like bone cells and produce calcium

Myxomatous Degeneration

weakening of connective tissue in the valve

makes the valve floppy or stretched

common cause of mitral regurgitation

CAD

reduced blood flow can damage the structures that support valve closure

most often leads to secondary mitral regurgitation

Congenital Defects

valve is abnormally formed before birth

may have the wrong number of cusps or improper shape

can cause stenosis or regurgitation sometimes not noticed until adulthood

Mitral Stenosis

narrowed mitral valve slows blood flow from the left atrium to the left ventricle

this increases afterload on the left atrium

causes → atrial fibrillation (A. fib), pulmonary congestion, and decreased SV

Afib

caused by stretching of the left atrium

increases the risk of clots and stroke (embolization)

Pulmonary Congestion

from pressure backing into the lungs

symptoms → SOB (dyspnea), trouble breathing when lying down (orthopnea), cough, and low oxygen levels (hypoxemia)

Low SV

due to reduced ventricular filling

symptoms → fatigue, weakness, and activity intolerance

Mitral Regurgitation

left atrial volume overload due to backflow of blood

left atrial enlargement over time

atrial fibrillation caused by stretching of the left atrium → increases risk of clot formation and embolization

left ventricular volume overload from increased preload → leads to ventricular dilation and eventual heart failure

causes pulmonary congestion

causes decreased forward flow (CO) → fatigue, weakness, activity intolerance

Mitral Prolapse

mitral valve leaflets bulge backward into the left atrium during systole

may cause the valve to open slight → can lead to mitral regurgitation

produces a systolic murmur (may include mid-systolic click) → caused by sudden tensing of mitral valve and chordae tendinae as valve prolapses into left atrium during contraction

symptoms → often asymptomatic, if regurgitation occurs symptoms resemble that

Aortic Stenosis

narrowing of the aortic valve obstructs blood flow from the left ventricle to the aorta → increases left ventricular afterload

leads to a systolic murmur (heard when heart contracts)

Aortic Stenosis Symptoms

angina → heart muscle isn’t getting enough oxygen

syncope → especially with exertion due to reduced cerebral perfusion

fatigue → from low CO

hypotension → from reduced forward flow into systemic circulation

weak peripheral pulses → due to poor SV

Aortic Regurgitation

aortic valve doesn’t fully close allowing blood to leak back into the left ventricle during diastole

causes a diastolic murmur (heard when heart relaxes)

Aortic Regurgitation Symptoms

increased ventricular preload → blood returns from the left atrium and leaks back from the aorta

increased SV → elevated systolic BP

backflow of blood → reduced diastolic BP

widened pulse pressure → bc of high systolic and low diastolic

bounding peripheral pulses → water hammer pulses feeling forceful and collapse quickly, cause by high systolic and rapid drop during diastolic

Valve Diagnosis

cardiac auscultation → detects murmurs and abnormal heart sounds

chest xray → shows heart size and pulmonary congestion

echo → visualizes valve structures and blood flow

ECG → identifies chamber enlargement or arrhythmias (afib)

doppler ultrasound → measured flow speed and direction across valves

cardiac MRI → detailed view of heart anatomy and function

coronary angiography → assesses coronary artery disease especially before valve surgery

Supportive Care

medications manage symptoms and prevent complications but do not repair or replace the damaged valve

Diuretics

reduce pulmonary congestion and fluid overload in heart failure symptoms

Beta Blockers

slow heart rate to improve ventricular filling time and reduce oxygen demand

helps with angina in aortic stenosis and controls rate in atrial fibrillation

decrease workload

Calcium Channel Blockers

controls heart rate and manages angina when beta blockers aren’t available

used in atrial fibrillation and lowers workload

Anticoagulants

prevents blood clots in atrial fibrillation or enlarged atria

required for patients with mechanical valve replacements

Valve Repair

fixes the patients own valve without removing it

corrects valve narrowing or leaking by repairing leaflets or opening fused parts

includes commissurotomy (surgical opening) and valvuloplasty (balloon widening)

Valve Replacement

removes the damaged valve and implants a mechanical or tissue valve

used when repair is not feasible or has failed

mechanical valves last longer but require lifelong anticoagulation

tissue valves wear out over time but usually don’t require lifelong blood thinners