Valvular Heart Disease Flashcards
What are the four phases of the cardiac cycle?
- Ventricular filling (Diastole)
- Isovolumetric contraction (Systole)
- Ejection (Systole)
- Isovolumetric relaxation (Diastole)
Each phase has distinct physiological events that contribute to heart function.
What occurs during ventricular filling?
Passive filling of the atria from the vena cava and pulmonary veins into the left and right atria, flowing into ventricles; mitral and tricuspid valves open, semilunar valves closed
At the end of diastole, atrial contraction occurs, contributing to ventricular filling.
What happens during isovolumetric contraction?
Pressure builds in the ventricles, causing closure of the AV valves; all valves are closed and ventricular pressure rises without volume change.
This phase is critical for assessing cardiac contractility.
What happens during ejection?
SYSTOLE where ventricular pressure exceeds the aorta and this triggers the opening of the semi-lunar valves and blood passes through to the rest of the body, where the end systolic volume is created and can be used to determine ejection fraction. Eventually ventricular pressure is below arterial pressure, so the semilunar valves close, creating a rise in arterial pressure
What causes the diacrotic notch?
The closure of the semilunar valves, which indicates end of systole closure and successful prevention of backflow stream.
What triggers the ejection phase of the cardiac cycle?
Ventricular pressure exceeds aortic pressure, opening the semilunar valves and allowing blood to flow into the aorta.
This phase results in the creation of end-systolic volume.
What is the dicrotic notch?
A rise in arterial pressure created by the closure of the semilunar valves, indicating the end of systole.
It is an important feature in arterial pressure waveform analysis.
What is isovolumetric relaxation?
DIASTOLE where both sets of valves are now closed and ventricular pressure begins to reduce to below atrial pressure, which leads to opening of the atrioventricular valves and restarting of the cycle
What does the S1 heart sound indicate?
Closure of the atrioventricular valves during early systole.
It is one of the primary heart sounds used in auscultation.
What does the S2 heart sound indicate?
Closure of the semilunar valves during late systole, creating a dicrotic notch on a graph.
S2 is typically louder than S1 due to higher pressures on the left side of the heart.
What is a split S2 heart sound?
Occurs when the closure of the aortic and pulmonary valves is out of sync, often normal during inspiration.
Pathological causes can include conditions like pulmonary hypertension and right bundle branch block.
What is paradoxical split S2?
Delay in closure of the aortic valve, causing greater splitting during expiration and pulmonary valve to close first.
This can occur due t conditions affecting the aortic valve such as severe aortic stenosis, hypertrophic obstructive cardiomyopathy or left bundle branch block.
This can occur due to conditions such as severe aortic stenosis.
What is fixed split S2?
Fixed split S2 is where there is a delay in closure of the pulmonary valves with no effect from insipiration.
This can occur due to an atrial septal defect, where expiration causes presssure in the right atrium to decrease as normal but high pressure blood flows abnormally from the left to the right atria through the defect, which disrupts the pressure gradient and delays closure of the PV valve.
What are the features of the mitral valve?
Mitral valve is bicuspid, with the anterior leaflet longer than the posterior leaflet.
What is S3 heart sound?
S3 heart sound is a low pitched sound in the isovolumetric diastole phase after S2, indicating fast ventricular filling. It can indicate systolic heart failure, where the left ventircle is compliant due to dilation. This sound occurs with mitral and aortic regurgitation.
This can be normal finding in children, pregnant women and young athletes.
What is the S4 heart sound?
S4 heart sound occurs prior to S1 heart sound in the diastole ventricular filling phase due to reduced ventricualr compliance And slow filling, assoicated with left ventircular hypertrophy.
What are the atrioventricular valves?
Atrioventricular valves consist of
-> Tricuspid
-> Mitral which is bicuspid, between the left atrium and ventricle and anterior leaflet is longer than left.
They are attached by fibrous cords called the chordate tendinae to connect it to the valve cusps at the papillary muscles on the ventricles, which work simultaneously to promote valve closure. Papillary muscles contract during ventricular systole to prevent valve prolapse into atria.
What is the consequence of volume overload?
Volume overload of the heart chamber causes eccentric hypertrophy, where dilatation thins the chamber walls, resulting in S3 heart sound due to issue with systole causing backflow of blood.
What is the consequence of pressure overload?
Pressure overload of the heart chamber causes concentric hypertrophy to enlarge the myocardial cells hypertrophy to accomodate for increased force of contraction, resulting in S4 heart sounds due to issue with diastole filling.
What is acute rheumatic fever?
Acute rheumatic fever is an autoimmune condition that occurs 2-4 weeks following a Group A Strep with a throat infection such as streptococcus pyogenes. This has an M protein that is targeted by immune cells, however its similar structure to cardiomycin results in molecular mimicry and susceptibility to pericarditis, myocarditis, mitral regurgitation, heart failure and infective endocarditis.
What is the presentation of acute rheumatic fever?
Clinical presentation is with fever, abdominal pain and epistaxis
JONES
* Joint pain with asymmetrical poly arterial IgA
* Carditis, resulting in chest pain, dyspnoea and palpitations. Pericarditis may resolve in haemodynamic instability while the myocarditis may result in acute heart failure and arrythmia. Endocarditis commonly affects the mitral valve most, followed by the aortic valve and tricuspid valve, where regurgitation and heart failure occur.
* Nodules that are subcutaneous found on the extensor regions of the hands,s feet and knees lasting for 2 weeks, occurring after pericarditis
* Erythema marginatum, where a large red circle with a clear border forms on the centre of the chest. It begins
* Syndenham’s chorea: involuntary jerky movements due to inflammation of the caudate nucleus and putamen, involved in movement regulation
What is the pathophysiology of mitral stenosis?
There is limitations to the passive filling of the left atria and pressure in the left atria increases, creating an abnormal pressure gradient that causes backflow into the pulmonary vasculature and resulting in pulmonary hypertension and congestive heart failure. There is also left atrial diliatation which may result in atrial fibrillation and increases the risk of emboli formation . The pulmonary hypertension may result in pulmonary and tricuspid valve regurgitation, leading to right sided heart failure. Normal ventricular function maintains normal cardiac output initially, however reduced filling in diastole due to stenosis leads to loss of compensatory increase in CO during exertion.
What is the presentation of mitral stenosis?
Patients typically present with symtpoms of heart failure with
Shortness of breath, Paroxysmal nocturnal dyspnoea: SOB which worsens at night
Ascites , Oedema Hepatomegaly Fatigue and weakness on exertion ( reduced cardiac ouptut)
There is a risk of atrial fibrillation due to left atrial volume and pressure overload.
What are signs of mitral stenosis?
Tapping apex beat
Palpable and louder S1 sound due to stiff mitral valve
Opening snap sound due to stiff mitral valve
Mid-diastolic rumbling murmur at left heart apex due to reduced filling
S4 heart sound
Parasternal heave due to right ventricle hypertrophy
Prominent a waves in JVP
Malar flush
These signs reflect the hemodynamic changes due to the narrowed valve.
What is the clinical presentation of acute rheumatic fever?
- Fever
- Abdominal pain
- Epistaxis
- Joint pain (JONES criteria)
- Carditis
- Nodules
- Erythema marginatum
- Syndenham’s chorea
The JONES criteria help in diagnosing this autoimmune condition.
What is the treatment for rheumatic fever?
- Prophylactic antibiotics (e.g., erythromycin, benzylpenicillin)
- Aspirin for inflammation
- Management of heart failure with diuretics, ACE inhibitors, and digoxin
Early treatment is important to prevent long-term complications.
What is Malar flush?
Malar flush may occur, where there is reddening across the nose and cheeks due to CO2 retention from mitral valve stenosis, where back pressure into the right ventricle reduces gas exchange in the lungs.
What are the signs of right sided heart failure?
Raised JVP
Pedal oedema and ascites
Hepatomegaly
Early diastolic murmur due to pulmonary regurgitation from pulmonary hypertension
Signs of left sided heart failure:
Orthopnea
Exertional dyspnoea
Paroxysmal nocturnal dyspnoea
Fatigue
What are the ECG findings for mitral stenosis?
ECG which shows:
bifid (double peaked) P waves indicating left atrial enlargement
Atrial fibrillation
Right axis deviation when right ventricle hypertrophy occurs due to pulmonary hypertension
What does X-ray show for mitral stenosis?
Double border of right ventricle, indicating hypertrophy
Pulmonary congestion
Enlargement of all heart chambers (severe stage)
Prominent pulmonary arteries indicating hypertension
Mac-Callum’s patch
Kerley B lines indicating pulmonary oedema
What is Mac-Callum’s patch?
Irregular area of thickening in the left atrial wall due to previous severe rheumatic fever endocarditis
How is mitral stenosis managed?
Management is dependent on symptom severity
Mild/conservative management: salt restriction, diuretics,
Prophylactic antibiotic benzylpenicillin for those with rheumatic fever
Anti-arrythmia drugs, beta blocker or calcium channel blocker for rate control
Anti-coagulants due to risk of blood clots
Diuretics to manage heart failure
What is the pathophysiology of mitral valve regurgitation?
The backflow of blood into the left atrium causes the left atria to increase with pressure and volume overload. Due to the regurgitation back into the left atria, during the diastolic filling phase, there is more blood in the left atria and this passes to the left ventricle which undergoes hypertrophy. The anelargmeent of the left atria may compress the oesophagus and cause Chronic mitral regurgitation causes Fatigue, palpitations diaphoresis, exertional dyspnoea and pedal oedema.
What are the acute causes of mitral regurgitation?
Acute causes include infective endocarditis, acute myocardial infarction or trauma to the valve.
What are the chronic causes of mitral regurgitation?
Chronic damage to the valve, from mitral valve prolapse, dilatation cardiomyopathy, collagen vascular disease or hypertrophic cardiomyoapthy.
How does MI cause mitral regurgitation?
Myocardial infarction due to papillary muscle rupture or cardiac remodelling, where infarction induces myocyte necrosis and recruitment of immune cells such as neutrophils and macrophages which cause further damage and increase the ifnarcted area. This region is unable to withstand the blood pressure, and results in thinning and dilatation of the left ventricle chamber and cause thinning and dilatation of the left ventricle and the infarcted area stretches. The remaining healthy cardiomycytes undergo hypertrophy due to their compensatory effort to maintain ejection fraction, which dilates the chamber further making it prone to mitral valve regurgitation. The neurohormonal activation of the RAAS system and sympathetic system can further induce fibrosis.
