Overview and definitions

Valvular abnormalities are becoming more prevalent in western society due to an ageing population. As such, a significant proportion of patients seen on a general cardiology take, and thus on cardiology wards, will need assessment and workup for valvular intervention. 

In this chapter we will look at the most common valvular abnormalities, their underlying pathologies and standard treatment strategies.

Primary and secondary valve disease

As a general rule, valve disease can be considered as primary or secondary.

Primary valve disease refers to abnormalities of the valve or valvular apparatus, while secondary valve disease refers to abnormalities of the annulus or chamber in which it sits. For example, infective endocarditis causing a perforation in a mitral valve leaflet would cause primary mitral regurgitation (MR), while dilation of the left ventricle in the context of heart failure would cause mitral annular dilation and secondary MR due to failure of leaflet coaptation. This is important, as the treatment for the same downstream effect will ultimately depend upon the upstream cause.

Acute and chronic valve disease

Valve disease can also be classified as acute or chronic. Acute valve disease, such as the aortic regurgitation (AR) seen in infective endocarditis, can present with significant haemodynamic instability, while chronic valve disease of similar severity may not cause such significant decompensation. This is due to the ability of the heart to adapt to changes in haemodynamic circumstances over time, but without time for this gradual adaptation diastolic filling pressures can increase significantly leading to pulmonary oedema and respiratory failure. As such, acute severe valve disease may be a surgical emergency, whereas chronic severe valve disease may allow for an elective outpatient approach to valve intervention.

Aortic Valve disease

Aortic Stenosis

Pathology and Epidemiology

The aortic valve is, in normal physiology, a tri-leaflet valve separating the left ventricle from the aortic root and the systemic circulation. Aortic stenosis (AS) thus refers to narrowing of the aortic valve. When the effective orifice area of the valve becomes significantly reduced, a greater force is required by the left ventricle to expel adequate blood volume through the aortic valve during systole. This leads to increased wall stress and compensatory hypertrophy of the left ventricular myocardium, a combination of which leads to the signs and symptoms of AS. 

AS typically occurs due to calcific degeneration of the valve over time, and is thus more common in the elderly population, with prevalence at 10% >80 years. If stenosis is found in younger populations, this is often in the context of a congenitally abnormal valve, such as a bicuspid valve. When found, patients with bicuspid valves should undergo assessment for associated abnormalities which typically involves cross sectional imaging of the heart and aorta, as bicuspid valves are associated with aortic root dilation and aortic coarctation. Rheumatic AS, though a possible cause, is no longer common in developed countries.

In rarer cases it can also occur due to subvalvular or supravalvular stenoses seen in the left ventricular outflow tract and aorta but these will not be covered here.

The natural history of AS is normally benign until it becomes severe. When severe and symptomatic, 5 year survival is between 15-50% and patients are at risk of sudden cardiac death.

Presentation – Symptoms

Patients can be entirely unaware of their valve disease, which may be picked up due to detection of a murmur on routine auscultation leading to further screening. Otherwise, if symptomatic the patient may present with a typical combination of shortness of breath on exertion, anginal chest pain, syncope or pre-syncope, dizziness or new heart failure. The anginal type chest pain can occur due to a combination of reduced outflow leading to impaired coronary perfusion, but also increased demand from a hypertrophied ventricle.

The difference in presentation is important as, in current guidelines, asymptomatic patients are typically not considered for interventional management unless in the presence of other significant findings, or undergoing surgery for an alternative pathology. Once patients become symptomatic, they have a poor prognosis if left untreated and thus will at least require consideration of workup for intervention.

Presentation – Signs

On basic examination one is likely to find a number of typical signs. These include:

• Slow-rising pulse
• Narrow pulse pressure
• Ejection systolic murmur loudest in the aortic region radiating to the carotids
• Soft A2

In addition, if the patient has developed heart failure as a result of their AS, they may have developed typical signs of heart failure with congestion such as peripheral oedema, bilateral crepitations on auscultation of the lungs and an elevated jugular venous pressure.

Diagnosis and Investigations

AS should be considered as a differential diagnosis with the above history. Confirmatory testing is typically with echocardiography, given that echo is relatively cheap, quick and is available every day of the week in many hospitals, and thus it is possible that this is data you may be asked to interpret in your exam.

Echocardiographic criteria are discussed below. Alongside these, often valve morphology will be included in a report in case the stenosis occurs in the context of a bicuspid aortic valve.

Alongside echocardiography, early investigations should include a 12-lead ECG, chest Xray, blood tests including full blood count, urea and electrolytes and NT pro-BNP. 

A 12-lead ECG may show signs of left ventricular hypertrophy with increased voltages and left axis deviation. Chest xray may show little aside from pulmonary congestion if present, while blood tests may show a significantly elevated NT pro BNP, while often other routine bloods can be normal.

For patients with asymptomatic severe disease, CT of the aortic can be used to assess valve calcium, and a treadmill test can be used to unmask symptoms that aren’t present at rest. 

If being considered for intervention then typically patients will undergo coronary artery assessment, either via invasive coronary angiography, or via CT coronary angiography. This is in order to assess whether there is significant coronary artery disease that will need concomitant bypass grafting, which, if present, would push the patient towards a surgical intervention as opposed to transcatheter.

Grading Severity 

Severity of AS is classified as mild, moderate or severe according to standard imaging parameters. Severity on echo is assessed by calculating the pressure gradient across the valve using the Bernoulli equation which can then be used to extrapolate an aortic valve area. An explanation of this is beyond the scope of this chapter but a table outlining relevant values for assessment of severity is included below.

Grading of severity	Echocardiographic indices
	AV Vmax (m/s)	Mean Gradient (mmHg)	AVA (cm2)	Dimensionless index
Mild	2.5 – 2.9	1.5	>0.5
Moderate	3.0 – 3.9	20-39	1.0-1.5	0.25-0.5
Severe	≥4.0	≥40	<1.0	<0.25
Table 1 – Echocardiographic grading of severity of AS, adapted from; https://echo.biomedcentral.com/articles/10.1530/ERP-20-0035 (AV Vmax – Aortic valve maximum velocity, m/s – Metres per second, mmHg – millimetres of mercury, AVA – aortic valve area, Dimensionless index – ratio of left ventricular outflow tract velocity time integral (VTI) to the VTI across the aortic valve.

Occasionally patients have values that do not fit nicely into the above table, where the velocity is not in the severe category but the aortic valve area or dimensionless index calculations would be classified as severe. In the first instance these values often need remeasurement as measuring error is a common cause for discordant grading. 

For patients with non-severe velocities but severe valve area calculations in the context of heart failure and reduced ejection fraction, a dobutamine stress echo can be performed to assess for an increase in velocity across the stenotic valve after the addition of an inotropic agent. If velocities then reach the severe range, then this confirms a diagnosis of severe, low-flow, low-gradient AS which is treated the same way as other forms of severe AS.

Criteria for interventional treatment 

Interventional management is typically not recommended until the valve lesion is considered to be severe and symptomatic. In this case, the patient can be referred for consideration of intervention which will be discussed below. 

If non-severe then the disease is typically followed up with routine outpatient echocardiography.

If stenosis is severe but the patient remains asymptomatic, currently a watch and wait strategy is recommended, unless the below criteria are met, in which case interventional treatment should be considered:

• LVEF <55% of no other cause
• Typical symptoms of AS on exercise testing
• Sustained fall in blood pressure (>20mmHg) on exercise testing
• Very severe stenosis (Vmax >5m/s, mean gradient >60mmHg)
• Severe valve calcification (males >2000 Agatston units, females >1200 Agatston units) 
• Aortic Vmax progression by ≥0.3m/s/year
• NT Pro BNP levels ≥3 x the upper limit of normal
• Undergoing cardiac surgery for an alternative reason such as coronary artery bypass grafting

If the patient’s lifespan is expected to be <1 year or there is another significant life-limiting comorbidity then it is likely that conservative management would be pursued instead, irrespective of disease severity.

Treatment options for severe AS

If heart failure is a consequence of AS then diuretics can be used for symptomatic management but there are no evidence-based pharmacological therapies for the definitive management of AS.

For a patient with limited quality of life and a poor prognosis irrespective of their valve disease then interventional management may not be suitable. In addition, it may be the patient’s wishes not to undergo any form of intervention which must be respected, along as they are making their decision with capacity in full understanding of the consequences. 

Aside from the above, the vast majority of patients fulfilling the above criteria will be offered interventional management for their valve disease. The two options here are surgical aortic valve replacement (SAVR) or transcatheter aortic valve replacement (TAVR).

SAVR

SAVR typically involves an open sternotomy with subsequent removal and replacement of the AV. The new valve can either be bioprosthetic (typically porcine or bovine pericardium is used), or mechanical. Within mechanical valves there are a number of different mechanical valve subtypes but this is beyond the scope of this chapter. 

Bioprosthetic valves typically have a lifespan of somewhere between 10-15 years though obviously there are exceptions to the rule. Towards the end of their lifespan they will begin to restenose, as turbulent flow through the valve causes degeneration and calcification.

In the absence of complications, mechanical valves will last for an entire lifespan, but necessitate lifelong anticoagulation with a vitamin K antagonist. The International normalised ratio (INR) target will vary dependent upon both valve characteristics and patient specific-factors and will typically be documented in the surgical notes. 

In the absence of an alternative indication for antiplatelet or anticoagulant therapy, current post-procedural antithrombotic/anticoagulant strategies in bioprosthetic valve replacements lack good quality evidence. Current guidelines recommend the use of either low dose aspirin (75-100mg OD) or anticoagulation with a vitamin K antagonist (VKA) for the first 3 months.

TAVR

TAVR typically involves accessing the femoral artery with large catheters, then feeding a new AV valve up the descending aorta and through the old diseased valve. Once in place the TAVR valve is then opened up inside the old valve. Once in place the TAVR acts similarly to the bioprosthetic AV valve. Subclavian and trans-apical TAVRs are also feasible but markedly less commonly performed. 

Subsequent to TAVR, it is recommended that patients remain on lifelong single antiplatelet therapy if there is no alternative indication for anticoagulation such as atrial fibrillation, in which case either a VKA or more likely direct oral anticoagulant (DOAC) would be continued post procedure.

Deciding between interventional therapies

Choice of therapies is typically made during a multidisciplinary team meeting. For those <75 years and low risk for surgery, or whose anatomy is unsuitable for TAVR, SAVR is typically recommended. For those >75 years or those who are high risk for surgery a TAVR is typically recommended. 

If being considered for TAVR then the patient will have a dedicated TAVR CT to assess femoral access and aortic root dimensions to assess for suitability. If either the access options or the morphology of the aortic root is not suitable for TAVR then this will be rejected. 

As part of the workup for valve intervention, most patients will be screened for concomitant coronary disease, either with a CT coronary angiogram or with invasive coronary angiography. For those patients with significant coronary disease (typically significant stenosis of the proximal left anterior descending or left main stem arteries) then they will be more likely to be offered a SAVR with concomitant coronary artery bypass grafting. Patients will also typically receive a dental check up to assess for ongoing dental disease which would need to be fixed prior to valve intervention, as well as pulmonary function testing, and carotid artery doppler assessment to assess for carotid artery pathology requiring intervention prior to valve intervention.

Balloon valvotomy

Balloon valvotomy involves placing a balloon through the diseased aortic valve and expanding it to increase the effective orifice area. As definitive management this is now effectively an outdated practice. Nowadays balloon valvotomy can be used as a palliative measure in certain patients, or as a temporising measure for an acutely unwell patient while awaiting definitive management.

Aortic Regurgitation

Pathology and Epidemiology

Aortic regurgitation is incompetence of the trileaflet aortic valve, leading to backwards flow from the aorta to the left ventricle during diastole. When significant this can lead to elevated filling pressures and wall stress, leading to elevated pulmonary pressures both of which ultimately lead to typical signs and symptoms.

In large case series it is the third most common valve disease after MR and AS with a prevalence of between 5-10%, though rarely are these cases severe.

Common primary causes of AR include bicuspid aortic valve, degenerative valve disease and infective endocarditis.

Relevant secondary causes of AR include aortic root dilation (typically caused by hypertension, with collagen and fibrillin disorders less common) and type A aortic dissection.

Presentation – Symptoms

Symptoms of AR depend on the acuity of the presentation. As discussed earlier, acute onset regurgitation does not allow time for the left ventricle to adapt to an increased stroke volume by dilating, and thus can lead to elevated wall stress, elevated diastolic pressures and pulmonary oedema alongside failure of forward flow leading to circulatory collapse. In contrast, compensatory adaptations can occur in the setting of chronic regurgitation so that when these compensatory mechanisms fail, the presenting symptoms are more typical of heart failure, i.e. shortness of breath on exertion, orthopnoea, fatigue and peripheral oedema. Some patients may complain of anginal type symptoms due to impaired diastolic perfusion in the coronary arteries due to retrograde flow.

Presentation – Signs

Signs typical of AR include:

• Early diastolic murmur, best heard in the aortic area in expiration and sitting forward
• There may also be a low-pitched late diastolic murmur heard at the apex called an Austin Flint murmur
• There may also be an additional systolic flow murmur due to elevated stroke volumes
• Wide pulse pressure
• Collapsing or ‘waterhammer’ peripheral pulse
• In chronic regurgitation, enlargement of the left ventricle can lead to lateral displacement of the apex on palpation
• In acute regurgitation alongside the above findings there may also be the typical signs of acute heart failure and cardiogenic shock, ie hypotension, peripheral vasoconstriction, bilateral crepitations on auscultation of the lungs, elevated jugular venous pressure
• If there is a specific underlying cause then there may be signs specific to this, ie splinter haemorrhages in infective endocarditis.

Diagnosis / Investigations

AR should be considered as a differential diagnosis with the above history and clinical signs. As per AS, confirmatory testing is typically with transthoracic echocardiography. In acute regurgitation, bedside echocardiography may be necessary in an acutely unwell patient, but they will also need formal departmental testing. 

TTE will show reversal of flow during diastole, evidenced by colour flow, pulse wave or continuous wave doppler. In addition, it may demonstrate the underlying causative pathology, be that significant root dilation or perforation of the valve leaflet.

Alongside TTE, early investigations should include a 12-lead ECG, chest Xray, blood tests including full blood count, urea and electrolytes and NT pro-BNP, as well as any further investigations to elucidate the cause, for example three sets of blood cultures when considering infective endocarditis, or CT angiography of the aortic root if considering aortic dissection as an underlying cause.

There are no specific ECG signs, though sequelae of underlying issues may be noted – ie PR prolongation in infective endocarditis with aortic root abscess, or ST depression in proximal aortic root dissection with coronary involvement.

Chest Xray will likely only show signs of decompensation such as pulmonary congestion and pleural effusion, though in chronic AR the cardiac shadow can be enlarged and laterally displaced.

Blood tests will likely be non-specific, though can indicate evidence of organ failure secondary to AR, while NT pro BNP values can help prognosticate.

Transoesophageal echocardiography is often performed to assess for mechanism of regurgitation, and can help plan surgical interventions. Cardiac MRI can also be used to quantify regurgitant volumes but is less commonly used in the acute phase. CT may be used to accurately map out aortic root dimensions, and is also a good modality for assessment of aortic root abscess formation if not clearly seen on transthoracic or transoesophageal echocardiogram.

Grading Severity 

As with AS, severity of AR is typically assessed with echocardiography. A number of parameters are used which are beyond the scope of this document, but severe AR is typically diagnosed in the context of a combination of the following:

• Flail leaflets
• Dense continuous wave doppler signal
• Holodiastolic flow reversal in the descending aorta
• Vena contracta >6mm
• Pressure half time <200ms
• Regurgitant volume >60ml
• Effective regurgitant orifice area >30mm²

Of these, holodiastolic flow reversal in the descending aorta is most specific for severe AR, but in general a combination of the above is considered.

Criteria for treatment 

If non-severe then AR is typically followed up with routine outpatient echocardiography, typically every year if moderate, and every 3-5 years if less severe.

As with AS, patients with symptomatic severe AR require consideration for intervention. In asymptomatic patients, intervention is typically recommended if resting LVEF is <50% or the left ventricular end systolic diameter is >50mm, or >25mm/m2 BSA.

As with AS, valve intervention can also be considered if a patient is undergoing CABG, aortic intervention or alternative valve surgery and has asymptomatic severe AR.

Treatment options

There are no particular medical treatments for AR, though diuretics can be given for symptom management, and typical heart failure therapies can be given in the context of a reduced LVEF.

Almost universally, surgical intervention is recommended for severe disease meeting the above criteria. If ineligible for surgical intervention, then some centres may consider TAVR as an alternative, though this is not common and SAVR may need to be considered as a bail-out therapy where TAVR is unsuccessful. SAVR options are the same as those for AS, discussed above.

When aortic root dilation is the underlying pathology, concomitant aortic root surgery is typically performed, and patients will again be screened for significant coronary artery disease as per AS in case simultaneous coronary artery bypass grafting needs to be performed.

Mitral Valve disease

Mitral Regurgitation

Pathology and Epidemiology

The mitral valve separates the morphological left atrium and ventricle and is composed of a narrow based but elongated anterior valve, and a broad based but shallow posterior valve. These are separated into three morphological regions termed scallops, delineated by two swallow indentations on the posterior leaflet. The subvalvular apparatus is comprised of the chordae which typically secure the valve leaflets to the anterolateral and posteromedial papillary muscles.

The mitral valve annulus is saddle shaped and comprised of a fibrous anterior portion in continuity with the aortic valve, while the posterior section is more loosely attached to adjacent tissue and is more mobile during the cardiac cycle.

Mitral regurgitation (MR) refers to retrograde flow of blood through the mitral valve during systole and can occur in the context of disease of any of the above components. As described earlier, primary valve disease occurs due to failure of either the valve leaflets or subvalvular apparatus, while secondary regurgitation is regurgitation through competent valve leaflets due to dilation or abnormalities of the annulus.

Trace or mild regurgitation is a common finding even in healthy hearts, and MR is the second most common valve disease after AS. 

Primary causes include infective endocarditis leading to valve perforation, degenerative or myxomatous valve disease, papillary muscle dysfunction or chordal rupture in the context of myocardial ischaemia.

Secondary causes include dilation of the left ventricle of any cause (such as a cardiomyopathy) and dilation of the left atrium of any cause (such as restrictive cardiomyopathies).

The distinction may seem arbitrary as it leads to the same process, but this difference is important as ultimately the treatment options for the two categories are markedly different.

Presentation – Symptoms

As with AR, the nature of the presentation depends on the acuity of the disease. In acute regurgitation there is little time for the heart to adapt to significant volume loading of the left ventricle which leads to increased diastolic filling pressures, wall stress and pulmonary congestion, and can lead to haemodynamic collapse. This can manifest as cardiogenic shock, with hypotension, diaphoresis, dyspnoea, reduced GCS, orthopnoea and peripheral oedema.  

 In chronic regurgitation, increased volume loading can be adapted for by dilation of both the left atrium and ventricle to accommodate an increased blood volume, and it is often only when these compensatory mechanisms have reached their limit that patients decompensate and present with typical symptoms of heart failure.

Presentation – Signs

Signs typical of severe MR include:

• Pansystolic murmur loudest in the apical region radiating to the axilla
• Displacement of the apex laterally due to LV dilation
• Crackles on auscultation of the lung if pulmonary congestion present
• If mitral valve prolapse is the cause, then a mid-systolic click can be heard

Signs typical of acute severe regurgitation are those of acute heart failure and cardiogenic shock, including:

• Hypotension
• Hypoxia
• Tachycardia
• Pulmonary congestion
• Reduced urine output
• Impaired cognitive function

Diagnosis / Investigations

Diagnosis should be considered in the context of the above findings. Patients will typically receive a chest Xray, ECG and TTE alongside blood tests which will normally include full blood count, urea and electrolytes and NT pro BNP levels.

Chest Xray can demonstrate a dilated cardiac shadow if chronic, while if symptomatic will often show pulmonary congestion with or without pleural effusions. ECG can show evidence of left atrial enlargement, P Mitrale, which manifests as a broad bifid P wave, otherwise may not show any specific signs for regurgitation.

TTE is the most useful test to make the diagnosis and severity criteria will be discussed below. Colour flow doppler can demonstrate the presence of MR visually, while a combination of spectral doppler and 2D measurements are used to grade severity. As with AR, transoesophageal echocardiography can be considered to better understand the underlying pathology and to help plan for intervention if required.

As with any cause of heart failure and increased wall stresses, NT Pro BNP levels will typically be elevated.

Once significant regurgitation is diagnosed, if a specific underlying cause is being considered then there may be additional tests directed at elucidating this; blood cultures will be relevant for those with infective endocarditis, while angiography may be necessary if ischaemia is the likely cause.

Grading Severity 

Echocardiography is the standard modality for assessment of severity. A number of parameters are typically used to adjudicate severity which are beyond what is required of you at MRCP, but regurgitation is likely severe if regurgitant volume is >60ml, regurgitant fraction is >50%, pulmonary vein flow is reversed in systole and the regurgitant jet takes up >50% of the left atrium on colour flow doppler.

Criteria for treatment 

Patients with severe symptomatic regurgitation typically need surgical intervention. For those with severe asymptomatic regurgitation, surgical intervention is typically recommended when the following criteria are met:

• LVEF <60% or LV end systolic diameter ≥40mm
• AF or pulmonary hypertension (systolic pulmonary artery pressure >50mmHg) secondary to the MR

Treatment options

The vast majority of patients with less than severe MR will need no specific treatment. 

In severe disease, medical therapy typically comprises of diuretics, and in acute disease nitrates can also be used if blood pressure is sufficient, in order to reduce filling pressures. In acute regurgitation with haemodynamic instability then inotropic agents and intra-aortic balloon pumps can also be considered to reduce afterload and improve preload thus increasing cardiac output.

For those patients who meet the above criteria for surgical intervention, repair of the mitral valve is normally preferred, but if not technically feasible then the valve can be replaced. Anticoagulation after repair is sometimes prescribed, though there is limited evidence for this.

As with aortic disease, both bioprosthetic and mechanical mitral valves are feasible. Regarding anticoagulation with vitamin K antagonists, due to lower velocity flow between the left atrium and ventricle, a higher INR is typically required in mechanical mitral prostheses and will typically be indicated in the surgical notes. 

For patients who are failing medical therapy and are not suitable for cardiac surgery then transcatheter options are now available, known as trans-catheter edge to edge repair or TEER. Their role is controversial however, with limited evidence of prognostic benefit and currently they are used largely with palliative intent.

Mitral stenosis

Pathology and Epidemiology

Mitral stenosis (MS) refers to narrowing of the mitral valve orifice. When severe, this leads to elevation of pressures in the left atrium and backwards into the pulmonary circulation. Historically it was more prevalent, typically caused by rheumatic fever as a delayed manifestation of group A streptococcal infection, but its incidence and prevalence is falling in the western world. As a consequence, an increasing proportion of cases are caused by calcific degenerative stenosis, seen in elderly patients. In both cases the mitral valve itself stiffens, leading to narrowing of the mitral orifice. 

Rheumatic disease leads to thickening of the mitral valve leaflet and commissural fusion with notably restricted motion at the leaflet tips. Shortening, calcification and fusion of the mitral chordae is also seen.

In calcific disease calcium deposits build up on the valve itself leading to thickening and calcification at the base of the leaflets impairing motion.

Other less common causes include mitral annular calcification, side effects of radiotherapy and congenital stenosis such as is seen in the Shone complex.

Presentation – Symptoms

Symptoms are typically related to either the presence of atrial fibrillation or elevated pulmonary pressures. In severe disease, significant elevation of pressures within the left atrium leads to atrial dilation which is a potent substrate for atrial fibrillation. This can thus lead to palpitations, dyspnoea and chest discomfort.

Alongside this, elevated pressures in the left atrium can lead to elevated pulmonary pressures. This can lead to exertional dyspnoea, cough, haemoptysis, chest pain due to elevated right ventricular pressures. These symptoms can be worse in the context of atrial fibrillation, as impaired atrial pump function can reduce forwards flow and further increase left atrial and thus pulmonary pressures.

Due to the high risk of atrial fibrillation and stasis within the left atrium they are at a markedly elevated risk of cerebrovascular accident which may be the first presenting feature. 

Significant MS is incredibly poorly tolerated in pregnancy. The haemodynamic changes of pregnancy include significant volume expansion, which becomes an issue when faced with a fixed obstruction between the left atrium and ventricle, typically leading to signs of heart failure in the second trimester which may be its first point of diagnosis.

Presentation – Signs

When severe there are a number of typical signs:

• Cutaneous vasodilation (mitral facies)
• Pulmonary congestion – rales
• Evidence of right sided heart failure – right parasternal heave, elevated jugular venous pressure, ascites, peripheral oedema
• Diastolic murmur heard best at the apex on expiration

Diagnosis and Investigations

As with previous diseases, the above constellation of symptoms and signs should suggest a differential of MS. They will typically undergo the same battery of tests as other potential valve disease cases including ECG, Chest Xray, Echocardiogram and routine blood tests.

ECG may demonstrate atrial fibrillation, P mitrale due to left atrial enlargement if in sinus rhythm and evidence of pulmonary hypertension such as right axis deviation and a tall R wave in V1 and V2.

Chest Xray may show signs of pulmonary congestion but is typically non-specific.

As with other valve disease, echocardiogram is the mainstay of diagnosis. Colour flow doppler will demonstrate turbulent anterograde mitral flow, while 2d views may show an echobright thickened base in calcific disease, while in rheumatic disease the leaflets themselves become thickened and may demonstrate a domed ‘hockey-stick’ type appearance. The left atrium is typically markedly dilated on 2d views and there may be evidence of spontaneous echo contrast within it, suggesting sluggish flow. Spectral doppler will demonstrate elevated trans mitral pressures, while a short axis view of the mitral valve leaflets tips is imperative.

Grading Severity 

Echocardiographic criteria are commonly used for grading MS. MS is classified as clinically significant when the mitral valve area is <1.5cm2. This encompasses moderate and severe MS. 

Other features suggestive of significant stenosis include a mean pressure gradient of >10mmHg, diastolic pressure half time of <220ms and systolic pulmonary artery pressure of >50mmHg.

Criteria for interventional treatment 

Intervention is typically reserved for symptomatic patients with moderate-severe rheumatic MS. Intervention can be considered in asymptomatic patients with either high thromboembolic risk (defined as previous systemic embolism, dense spontaneous echo contrast in the left atrium or new atrial fibrillation) or high risk of haemodynamic compensation (defined as systolic pulmonary artery pressure of >50mmHg at rest, need for a major non cardiac surgery or desire for pregnancy).

For those with degenerative disease, evaluation of severity is difficulty and many of the above parameters lack validation in this cohort. Mean transmitral gradient has been shown to have prognostic value but a holistic assessment of the patient is required.

Treatment options

Percutaneous mitral commissurotomy is typically first line in symptomatic rheumatic valve patients with favourable characteristics. Unfavourable characteristics which would preclude PMC include old age, previous commissurotomy, NYHA class IV, permanent AF, severe pulmonary hypertension, very small valve area, more than mild MR or a left atrial thrombus. Where alternative surgery is to be performed (such as in CABG or if concomitant valve disease requiring intervention) then surgery is likely to be preferred to PMC.

Mitral valve replacement surgery can be performed for symptomatic patients who are not suitable for PMC due to the above unfavourable characteristics.

Intervention in degenerative MS is performed less commonly. Degenerative MS is not amenable to transcatheter intervention and surgery is both challenging and without good outcome data.

Medical therapy typically includes anticoagulation in all patients with significant mitral stenosis with atrial fibrillation, irrespective of CHADS-VaSC score. These patients will require vitamin K antagonists not DOACs which have been shown to be less effective. Aside from this, diuretics and rate control medications (such as beta blockers, calcium channel blockers and ivabradine) can help with symptom control. The former helps to offload the heart, while the latter slows the heart rate, allowing for a longer time in diastole for blood to move through the stenotic valve, both ultimately aiming to help improve dyspnoea.

Tricuspid valve disease

Tricuspid regurgitation

Pathology and Epidemiology

Tricuspid regurgitation (TR) is a common finding in the general population, while at least moderate regurgitation is present in 0.55% of the general population, with prevalence increasing with age.

It is overwhelmingly secondary in nature, with >90% of cases due to either pressure or volume loading of the right ventricle or atrial dilation. In the context of HFrEF, tricuspid regurgitation is a very common finding due to elevated pulmonary pressures.

Primary valve disease aetiology is similar in nature to mitral disease, with infective endocarditis and degenerative valve disease common causes, though rarer disease such as carcinoid syndrome, iatrogenic damage secondary to pacing devices or congenital abnormalities such as Ebstein’s anomaly are other recognised causes.

Presentation – Symptoms

TR can be well tolerated for long periods of time. When more severe it can be associated with signs of right heart failure, including:

• Dyspnoea
• Fatigue
• Cyanosis
• Peripheral oedema
• Right upper quadrant pain due to hepatic congestion

As with other valve diseases, if there is a specific underlying cause then there may be symptoms specific to that disease ie splinter haemorrhages in infective endocarditis, flushing and diarrhoea in carcinoid syndrome or symptoms of heart failure in secondary regurgitation due to HFrEF.

Presentation – Signs

Signs of TR are typically those of right sided heart failure, including peripheral oedema, ascites, raised jugular venous pressure and right upper quadrant tenderness.

Signs specific to TR will include:

• High pitched systolic murmur in the tricuspid region, louder on inspiration
• Loud P2 (in absence of pulmonary hypertension)

Diagnosis and Investigations

Significant TR is often found incidentally due to a clinical diagnosis of heart failure. Typical workup will include standard investigations mentioned above, ECG, chest Xray, echocardiogram and blood tests.

ECG will likely be non-specific, though there may be evidence of P pulmonale with peaked P waves, there may be complete or incomplete right bundle branch block. Chest Xray may show cardiomegaly, pleural effusions and pulmonary congestion.

Routine blood tests may demonstrate obstructive liver function tests due to the congestion alongside elevated NT pro BNP due to increased cardiac wall stress.

Echocardiography will demonstrate evidence of regurgitation on colour flow and spectral doppler, while 2d may suggest the aetiology, be it RV dilation, valve leaflet perforation or displaced tricuspid leaflet in Ebstein’s anomaly.

Grading Severity 

Severity is typically graded using a range of echocardiographic parameters including spectral doppler profile, vena contracta width, systolic flow reversal in the hepatic veins and regurgitant volume. The knowledge of these values is beyond requirements at MRCP. 

Alongside echo, cardiac MRI is often used to help evaluate the right ventricle morphology and function, as direct morphological and functional assessment is challenging with echo.

Treatment options

Medical therapy of TR is typically limited to diuretics to help offload the right ventricle.

Surgical tricuspid valve replacement is possible in both primary and secondary TR. In secondary regurgitation annuloplasty with prosthetic rings is preferable to replacement where technically feasible.

Like transcatheter mitral edge to edge repair, similar technologies are being developed for the tricuspid valve, though these remain in their infancy and are not commonly performed outside of research setting.

Criteria for interventional treatment 

In primary TR, surgery is recommended for severe disease if either the patient is undergoing left sided valve surgery, or there is evidence of isolated severe primary TR. The strength of both these recommendations however is low.

In secondary TR, surgery is recommended in severe disease for patients undergoing left sided valve surgery, or in those with significant symptoms or RV dilation in the absence of severe RV dysfunction, severe LV dysfunction or severe pulmonary hypertension.

Prosthetic valves

The term prosthetic valve refers to non-native valves inserted in the place (or indeed inside) of a defective valve. These valves are typically divided up into the following:

• Mechanical
• Bioprosthetic
• Transcatheter

Mechanical and bioprosthetic valves can be implanted in any location, while transcatheter valves are typically reserved for the aortic and pulmonary positions, though mitral valves have also been attempted. Bioprosethetic valves can also be called xenografts given they contain biological material from another species.

A side note are homografts and autografts – homografts are valves taken from deceased donors, while autografts are the patients’ own valves, excised and reimplanted in an alternative location. 

Homografts are not commonly used due to their lack of availability, though they have at least equal outcomes in comparison to xenografts. Autografts are most commonly used in the Ross procedure – use of the pulmonary valve transposed into the aortic position with an aortic homograft.

Mechanical valves

Mechanical valves are synthetic, typically a mix of carbon and metal, and come in a variety of designs and sizes. In the absence of complications, their lifespan can outlast that of the patient but they require lifelong anticoagulation with a vitamin K antagonist such as warfarin as DOACs have been shown to be less effective. The INR target range is dependent upon patient and anatomical factors, with valves in the mitral position typically requiring higher INR targets (typically 3-4) due to the lower flow velocity compared to the aortic position (typically 2.5-3.5). Complications of mechanical valves include bleeding, infection of prosthetic material, dehiscence of the valve and obstruction of the valve due to clot. 

Bleeding can occur in the setting of excess anticoagulation, while any prosthetic material in the body serves as a nidus for infection, thus all patients with prosthetic material are advised to be rigorous in their dental hygiene and to avoid tattoos and piercings where possible to avoid a potential route for the seeding of bacteria. Dehiscence (or displacement) of the valve can occur in the context of endocarditis, or less commonly due to ineffective suturing coming loose. Obstruction of the valve due to clot is an emergency as it will lead to haemodynamic collapse if it significantly impedes flow and will need treatment with either lysis via heparinisation or thrombolytics, or emergency valve surgery. This is typically demonstrated by evidence of higher velocity flow through the valve with evidence of reduced or arrested valve leaflet motion on imaging tests.

Bioprosthetic valves

Bioprosthetic valves are typically made of bovine or porcine pericardium. Their lifespan typically sits in the range of between 10-20 years, with certain factors such as hypertension, hyperparathyroidism, end stage renal disease and diabetes mellitus reducing durability and valve lifespan. Unlike mechanical valve replacement there is a lack of clear evidence on the need for anticoagulation. European guidelines suggest that in the absence of other reasons for anticoagulation, either aspirin or a VKA can be considered for the first 3 months after a biological prosthesis is inserted in the aortic position, while VKA should be considered for the first three months for those with a biological prosthesis in the mitral or tricuspid positions. 

Complications are as above for mechanical prosthesis, though thrombosis is less commonly encountered. They remain a nidus for infection given the prosthetic material and lack of good blood flow to the valves.

Transcatheter valves

Transcatheter valves are those implanted through a catheter, most commonly in the aortic position. The benefit of these valves compared to those above is that they don’t require open cardiac surgery. As such, they can be considered in patients who have contraindications to surgery, including those with significant comorbidities and frailty. 

For the aortic TAVI there are a number of approaches, but transfemoral is overwhelmingly the most common. In this approach, a catheter is inserted into the femoral artery under local anaesthetic and sedation and fed retrogradely into the aortic position. Balloon valvuloplasty is performed, then under rapid pacing (to stop LV systolic flow displacing the new valve) a new valve is deployed in the aortic position and the catheter is removed. Newer versions of these valves are typically self-expandable. 

Given that they are performed under local anaesthetic and sedation, patients can typically be considered for discharge within 48 hours if there are no immediate complications. Common complications of TAVI can include conduction system abnormalities requiring need for pacing, alongside wound site issues with bleeding or infection. 

Subsequent to transcatheter aortic valve implantation, patients will typically be given a low dose single antiplatelet drug lifelong, commonly aspirin.

Choosing between valve types

Transcatheter valves are used less commonly, and typically only in the aortic and occasionally in the pulmonary position. In the aortic position TAVR is typically preferred if patients are >75 years or unsuitable for SAVR due to comorbidities or surgical risk, while SAVR is preferred if <75 years or low surgical risk.

Within surgical replacement, guidelines recommend mechanical prostheses if:

• According to patient preference
• Risk of accelerated valve dysfunction – young patients <40, hyperparathyroidism, dialysis patients
• <60 years for prosthesis in the aortic position, <65 years in the mitral position
• Patients for whom redo surgery or future TAVI would be high risk

Bioprosthetic valves are recommended if:

• According to patient preference
• Anticoagulation adherence is likely to be poor or contraindicated – typically due to high bleeding risk
• Young women considering pregnancy due to the teratogenic nature of vitamin k antagonists
• Life expectancy is lower than the presumed durability of the bioprosthesis
• In case of re-operation for mechanical valve thrombosis despite good anticoagulant adherence
• >65 years in the aortic position or >70 in the mitral position

Other valvular disease

Tricuspid stenosis

Stenosis of the tricuspid valve is uncommon. Where it occurs, it is frequently rheumatic in origin and thus associated with other valve disease. Other causes include carcinoid and drug-induced valve disease. Echocardiography is the primary form of assessment, and while there are no standard criteria for stenosis, 2d assessment of morphology and transtricuspid gradient of >5mmHg is suggestive of tricuspid stenosis. Interventional treatment, where required, is typically performed with bioprosthetic valves due to high rates of mechanical valve thrombosis.

Symptoms and will typically be those of right heart failure and venous congestion, while signs will include a raised JVP, peripheral oedema and a systolic murmur heard loudest at the left upper sternal edge on inspiration.

Pulmonary regurgitation

Pulmonary regurgitation of any degree is frequently noted on echocardiography. Isolated pulmonary regurgitation is rarely symptomatic but for those patients with severe valve disease, replacement can be considered but it is not a common procedure. 

Where present it is often congenital, or can be acquired after surgical repair of the pulmonary stenosis seen in tetralogy of Fallot. 

Echo criteria for severe pulmonary regurgitation are less well validated, though colour flow reversal of pulmonary flow seen in a branch pulmonary artery is suggestive of severe disease.

Symptoms and signs of severe disease will include those of right heart volume overloading – raised JVP, peripheral oedema and ascites.

Pulmonary stenosis

Stenosis of the pulmonary valve is another uncommon disease and, where seen, is mostly congenital in nature. Significant stenosis can be seen as part of the tetralogy of Fallot, but mid stenosis is typically asymptomatic and has a long-term benign prognosis. Where needed, interventional treatment is typically with percutaneous balloon valvuloplasty and surgical intervention and valve replacement is reserved only for those cases that have failed percutaneous treatment or otherwise have a contraindication.