Aortic valve stenosis I35.0

Author: Dr. med. S. Leah Schröder-Bergmann

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Last updated on: 29.10.2020

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Synonym(s)

Aortic Stenosis

Definition
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In aortic valve stenosis, the heart valve becomes adhesions. The resulting restriction of mobility leads to a reduction of the valve opening area and thus to an obstruction of the forward blood flow (Herold 2018 / Anschütz 1974).

    Classification
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    Depending on the location of the stenosis, the AS is divided into:

    • in the case of a constriction at valve height, we speak of a valvular AS
    • in case of a constriction below the aortic valve from a subvalvular AS
    • in case of a narrowing above the aortic valve from supravalvular AS

    Congenital stenoses of the aorta can occur in all 3 forms, acquired almost exclusively as valvular form (Gieretz 2010)

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    Occurrence/Epidemiology
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    Aortic valve stenosis (AS) is the most common form of valve disease in Europe and North America (Herold 2018), accounting for 43% of all heart valve defects. The disease affects 80 % of the male sex (Bob 2001).

    Patients between the ages of 16 and 65 years of age usually have a congenital bicuspid aortic valve, while older patients have a mostly tricuspid aortic valve with stenosis and calcification (Krakow 2005). Of the over 75-year-olds, about 4% are affected by AS (Pinger 2019).

    Etiopathogenesis
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    Pathophysiologically, the following changes can be found in AS: the pressure load on the left ventricle leads to a concentric hypertrophy. However, this does not always have to be present. Initially, the left ventricle is still able to overcome the pressure gradient at the valve and can thus maintain cardiac output (CPV). Progressive symptoms are usually primarily diastolic dysfunction with congestion of the lungs. Hypertrophy of the left ventricle increases the oxygen demand of the cardiac muscles. The wall tension of the ventricle increases and impairs the subendocardial blood flow. In addition, left ventricular baroreceptors may respond incorrectly, causing peripheral vasodilation (Herold 2018).

    The causes of aortic valve stenosis are:

    • Degenerative changes as a result of calcification: In industrialized countries calcification in older people > 70 years is now the most common cause of AS in older people with about 50%. In the bicuspid aortic valve, the stenosis develops already in earlier years (mostly between the age of 50 and 70 years), in the tricuspid valve it develops later between the age of 70 and 90 years.
    • Congenital aortic valve stenosis: Younger adults often have a congenital aortic valve stenosis. This is usually a bicuspid valve.
    • Subvalvular or supravalvular congenital aortic valve stenosis (very rare, e.g. Williams-Beuren syndrome)
    • Inflammatory processes: Inflammations of different aetiology lead to a thickening of the pocket flaps and to a sticking of the commissures, which cause calcification in the further course. The stenosis is usually combined with aortic valve insufficiency. However, this cause is now rarely found in industrialized countries thanks to consistent antibiotic treatment.
    • Z. n. Radio (Kasper 2015)

    Clinical features
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    According to Schuler (2017), the course of AS is divided into 4 stages:

    1. Stage A: Sclerosis of a tricuspid valve or presence of a bicuspid valve
    2. Stage B (also known as progressive aortic valve stenosis): mild to moderate stenosis as shown in the echocardiogram
    3. Stage C: There is a hemodynamically severe AS, but without symptoms
    4. Stage D: A haemodynamically severe AS is found with symptoms

    In healthy adults the size of the opening area is between 2.6 - 3.5 cm². Before there is a hemodynamic effect, the opening area must decrease to < 1.5 cm². In a high-grade one the opening area is defined by an opening area of < 1.0 cm² (may well be asymptomatic). The pressure gradient is therefore not a mandatory criterion for defining the functionality of aortic valve stenosis in patients with limited left ventricular function (Herold 2018).

    As a rule, patients become symptomatic from an opening area of < 1.0 cm², a mean gradient of > 40 mmHg. This constellation usually occurs only in the 6th - 8th decade of life. In patients with bicuspid aortic valve the symptoms develop about 10 - 20 years earlier (Pinger 2019).

    The so-called cardinal symptoms include (Kasper 2015):

    • Dyspnea on exertion
    • pektanginous complaints
    • Syncopes

    Due to the increasing congestion of the lungs, a:

    • performance reduction
    • Dyspnea.

    By restricting the subendocardial blood flow due to the ventricular hypertrophy to:

    • Angina pectoris.

    Due to a false response of left ventricular baroreceptors to:

    • Vertigo
    • Syncope.

    Furthermore:

    • Cardiac arrhythmia
    • sudden cardiac death during physical exertion (occurs almost only in symptomatic patients).

    Imaging
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    X-ray:

    As long as the AS is in a compensated state, the heart is radiologically inconspicuous. According to Pinger (2019), it only occurs after decompensation has developed:

    • Widening of the left heart by enlargement of the left ventricle
    • Signs of congestion in the lungs with decompensation
    • Detection of flap lime
    • in valvular AS poststenotic dilatation of the ascending aorta
    • rounded apex of the heart (aortal configuration)
    • in the further course dilatation of the left atrium
    • Possible mitral configuration in case of mitral valve involvement (secondary mitral insufficiency)

    In MRI, the anatomy and function of the heart can be well assessed. The following values can be determined additionally:

    • the pressure gradient over the stenosis
    • the valve opening area using planimetry (However, the KÖF is in some cases clearly overestimated compared to the determination according to Gorlin: KÖF in the MRI 0.91 cm² vs. 0.64 cm² . The sensitivity and specificity for a KÖF < 0.8 cm² is 78 % and 89 %, respectively. [Pinger 2019])

    Diagnosis
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    Inspection and palpation:

    • Cyanosis, paleness is rare (Pinger 2019)
    • Pulsus tardus et parvus (typical symptom, but - especially in older patients - rarely occurring)
    • Tip of the heart broadened and lifted (according to Pinger [2019] also shifted to the left)
    • systolic buzzing above the aorta and in the carotid

    Auscultation: The leading symptom of aortic valve stenosis is a

    • spindle-shaped rough systolic
      • Punctum maximum in 2nd ICR right parasternal
      • with conduction into the carotides
      • weaned off the first heartbeat
      • the more pronounced the stenosis is, the more the noise maximum shifts to the late systole
    • early systolic ejection click (this is missing when the valve is immobile)
    • Attenuation of the aortic portion of the 2nd heart sound in high-grade stenosis
    • the 2nd heartbeat is split in a breath variable way
    • the 2nd heart sound can show a paradoxical split in a high-grade stenosis
    • Diastolic with concomitant aortic valve insufficiency

    ECG:

    The ECG only shows changes after a more severe stenosis. However, signs of hypertrophy may be absent even in severe AS.

    • Link type
    • signs of left hypertrophy (Sokolov-Lyon index: SV1 + RV5 or RV6 > 3.5 mV)
    • T- Negativation left precordial V4- 6 as a sign of hypertrophy

    Exercise ECG (Pinger 2019):

    In case of aortic valve stenosis, the exercise ECG cannot be used to diagnose coronary artery disease. In this case it is only used to confirm the suspected stress-independent symptoms.

    There is no indication to perform a stress ECG in patients with clear symptoms of AS.

    BNP:

    The BNP value plays an important role with regard to life expectancy (see below under Prognosis) and should therefore be determined by laboratory chemistry (Pinger 2019).
    Magnetic Resonance Imaging

    Echocardiography / Doppler

    In stenoses, the so-called pressure gradient is determined echocardiographically. The following applies to the aortic valve:

    • the pressure gradient depends on the pumping function of the ventricle as well as on the valve opening area (Herold 2018).

    The individual examination steps (Pinger 2019):

    • Quantification of the stenosis using the maximum instantaneous and mean pressure gradient across the valve (the maximum instantaneous and mean pressure gradient is calculated from the measured maximum and mean flow velocity using the modified Bernoulli equation [Pinger 2019])
    • Calculation of the flap opening area (here there are 3 different possibilities:
      • 1. Using the continuity equation (A1 x V1 = A2 x V2)
      • 2. by transthoracic planimetry
      • 3. by transesophageal planimetry
    • Size measurement of all atria and ventricles (high-grade stenosis is also possible in the absence of hypertrophy (Pinger 2019)
    • Assessment of a possible co-participation of the other flaps
    • the pressure conditions in the small circuit should be estimated
    • the maximum flow velocity, the mean gradient and the flap opening area (KÖF) should always be indicated (Pinger 2019)

    Particular attention should be paid to the following findings:

    • Anomaly of the pockets (bi- or tricuspid system)
    • calcified or fibrotically thickened aortic valve pockets
    • in calcifying AS there is a reduced valve separation
    • If the valve is only slightly calcified, there may be a dome-shaped dome position of the pockets during systole
    • left ventricular concentric hypertrophy
    • Evidence of a simultaneously existing aortic valve insufficiency due to reflux in the color Doppler
    • possible dilatation of the ascending aorta (usually occurs in connection with a bicuspid valve)

    The severity of the stenosis is classified as low, medium or high depending on the valve opening area and the gradients above the valve (Herold 2018).

    Light AS:

    • HEAD > 1.5 cm²
    • medium pressure gradient < 25 mmHg
    • Flow velocity < 3 m/s

    Moderate AS:

    • COP 1.0 cm² - 1.5 cm²
    • medium pressure gradient 25 - 40 mmHg
    • Flow velocity 3 - 4 m/s

    Heavy AS:

    According to Pinger (2019), the following criteria are found echocardiographically in a high-grade stenosis of the arterial valves:

    • valve opening area < 1.0 cm² or < 0.6 cm²/ m² (in relation to the body surface)
    • the mean pressure gradient is > 40 mmHg
    • the maximum flow velocity is > 4.0 m/s (for patients with normal transvalvular flow or normal HZV)
    • Speed ratio < 0.25

    Coronary angiography: A coronary angiography is indicated if coronary heart disease is also suspected. This applies to approx. 35 % of patients with aortic valve stenosis (Bonzel 2009). In 2019 this number will already be up to 50% of cases (Pinger). After ESC there is a preoperative indication for coronary angiography (Pinger 2019):

    • anamnestically known coronary artery disease
    • left ventricular dysfunction
    • Especially myocardial ischemia
    • postmenopausal women and men > 40 years
    • Presence of at least one cardiovascular risk factor
    • secondary mitral regurgitation for evaluation

    The indication for retrograde probing of the aortic valve should be made carefully, as the risk of embolization can be up to 22% (Omran 2003).

    Manometry: When measuring pressure, the systolic (peak-to-peak) and mean gradient over the valve (measured between left ventricle and aorta) and the valve opening area should be calculated.

    • Peak-to-peak gradient: This represents the difference in pressure between maximum systolic pressure in the left ventricle and maximum systolic pressure in the aorta. It cannot be measured exactly by Doppler sonography because the peaks do not exist at the same time and therefore a measurement of the pressure difference cannot actually be measured.
    • maximum instantaneous gradient: This is the instantaneous maximum pressure difference between the systolic pressure in the left ventricle and the systolic aortic pressure. This is measured during simultaneous registration.
    • Mean gradient: The mean gradient is an area integral between the pressure curve of the left ventricle and the aortic pressure curve, also with simultaneous recording.

    The gradient is dependent on the degree of stenosis, but also on the blood flow through the valve and thus the CPR. If ventricular function is restricted, a low gradient may be found, but a relevant stenosis may still be present. Here the valve opening area (KÖF) plays an important role. It can be calculated using the Gorlin formula.

    The classification of an AS is not uniform in the literature (Herold 2018).

    Grading of the severity of an AS according to the pressure gradient (Krakow 2005):

    • Grade I < 40 mmHg
    • Grade II 40 - 80 mmHg
    • Grade III 80 - 120 mmHg
    • Grade IV > 120 mmHg

    Classification of severity according to the valve opening area (Cracow 2005):

    • light grade: > 1,5 cm²
    • medium 0.8 - 1.5 cm²
    • severe 0.4 - 0.7 cm²
    • critical < 0.4 cm²

    Graduation of severity according to the maximum transvalvular flow velocity:

    • light AS < 3,0 m/s
    • medium AS 3,0 - 4, 0 m/s
    • heavy AS > 4,0 m/s

    (Herald 2018)

    "Low-grade aortic valve stenosis

    Low-gradient" aortic valve stenosis represents a particular challenge for the examiner in terms of classifying the severity of AS and thus also for the delivery of optimal therapy.

    Low flow in combination with a low gradient can be the consequence of systolic and diastolic dysfunction in high grade aortic valve stenosis as well as the consequence of moderate stenosis in connection with a non-valvular cause (a so-called pseudoaortic valve stenosis). Since only patients in the first group would benefit from aortic valve replacement, it is important to differentiate between the two causes (Herrmann 2013).

    Patients with pseudoaortic valve stenosis caused by dilated cardiomyopathy would not benefit from surgical valve replacement; in this group of patients, valve replacement is associated with high mortality. Therefore, the differentiation between pseudostenosis and severe aortic valve stenosis is crucial for the further therapeutic consequences. This is achieved by interventional increase of the low flow, which is performed by stress echocardiography with dobutamine. In pseudostenosis, only a minimal increase of the transvalvular gradient occurs with an increase of the effective orifice area (EOA).

    In fixed aortic valve stenosis, however, the catecholamine-induced increase in stroke volume leads to an increase in the transvalvular gradient with constant valve opening area.

    (Schuler 2017)

    Differential diagnosis
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    • Mitral valve insufficiency
    • Pulmonary Stenosis
    • Ventricular septal defect

    (Bob 2001)

    Complication(s)
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    • Cardiac arrhythmia
    • Left heart failure
    • sudden cardiac death (20%)

    (Herald 2018)

    Therapy
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    Until 2002, the treatment of symptomatic aortic stenosis was exclusively surgical. After A. Cribier introduced catheter-assisted implantation, valve replacement by TAVI was initially performed exclusively on inoperable patients or patients at high risk of surgery.

    In the meantime, however, randomized, controlled studies of patients with intermediate risk have also been conducted. These studies have shown that TAVI is equivalent to surgical valve replacement. However, TAVI is associated with more vascular complications, paravalvular leakage and pacemaker implantation. On the other hand, the surgical group had more general bleeding complications, acute renal failure, and unknown atrial fibrillation.

    These studies were included for the first time in the 2017 update of the ESC guidelines and subsequently transfemoral TAVI was issued as a Class I b guideline recommendation for patients at intermediate risk and thus equated to surgical therapy.

    (Ince 2018)

    According to the ESC guidelines of 2017, the following conditions are present in aortic valve stenosis

    1. evidence level IB:

    - in symptomatic patients with severe AS, surgical removal of the stenosis should be performed immediately

    2nd evidence level IC:

    - symptomatic patients with relevant low-flow, low-gradient stenosis and reduced left ventricular function

    - asymptomatic patients with severe aortic stenosis and reduced systolic function of the left ventricle (EF < 50 %) without other causes

    - asymptomatic patients with severe aortic stenosis and the appearance of symptoms during the stress test

    3. evidence level IIaC:

    - symptomatic patients with relevant low-flow, low-gradient stenosis while maintaining left ventricular function

    - asymptomatic patients with severe aortic stenosis and medium to highly calcified aortic valve as well as rapid hemodynamic progression (i.e. increase in aortic valve V max> 03, m/s/year)

    - asymptomatic patients with severe aortic stenosis and a drop in blood pressure below the baseline value at the stress test

    - asymptomatic patients with severe aortic stenosis and high BNP (B- natriuretic peptide)

    (Herald 2019)

    Symptomatic patients can choose between surgery and TAVI. The decision on this should always be based on individual risk assessment.

    Surgery should rather be considered in patients with a low risk of surgery (STS or EURO score II < 4 %, recommendation class IB)

    TAVI is recommended for patients with medium or high risk (STS or EURO score II ≥ 4%, recommendation class IB)

    The decision of a TAVI should - in the case of patients not suitable for surgery - be made jointly by the Heart Team (cardiology, cardiosurgery, cardiac anesthesia).

    (Herald 2019)

    TAVI is not recommended for asymptomatic patients. In this case, the procedure is always surgical. However, if the above mentioned additional criteria are not fulfilled in asymptomatic patients, one can wait carefully and proceed according to the above mentioned ESC Guidelines (Herold 2019).

    Patients with severe AS should avoid major efforts and competitive sports. Dehydration or hypovolemia must also be avoided at all costs, as otherwise there may be a significant reduction in stroke volume (Kasper 2015).

    In the case of a proven severe aortic valve stenosis with exclusion of pseudoaortic valve stenosis of the so-called "low- gradient" aortic valve stenosis, a drug therapy of the accompanying heart failure is not effectively possible. The only therapeutic measure is surgical intervention (Herold 2018).

    The situation is different with drugs used to treat hypertension or coronary heart disease. Beta-receptor blockers and ACE inhibitors can be given to asymptomatic patients without any problems, as can nitrates (Kasper 2015). In a retrospective study, patients with degenerative calcifying aortic valve stenosis showed slower progression of both calcification and opening area decrease in a retrospective study with HMG-CoA-reductase inhibitors (statins). However, this result could not be reproduced in randomized prospective studies. Nevertheless, the use of statins is recommended (Kasper 2015).

    For more details on the surgical measure see below valve replacement

    Progression/forecast
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    Follow-up examinations are recommended every 3 years for patients with mild and until then asymptomatic AS. In the case of more severe, but previously asymptomatic courses of AS, follow-up examinations should already take place at 6 to 12-month intervals (Herold 2018). The pressure load caused by stenosis of the valves is much more stressful for the heart than the volume load caused by valve insufficiency. Therefore, a stenosis of the heart valves generally has the less favourable prognosis. Nevertheless, approx. 50% of patients remain asymptomatic for years - despite severe stenosis. However, closer anamnestic questioning often reveals that the patients unconsciously spare themselves physically and thus prevent any possible symptomatology (Herold 2018).

    The BNP value plays a major role in life expectancy (Pinger 2019). In patients with a high-grade aortic valve stenosis at low pressure gradient, the 1-year survival rate is:

    • 47 % with a BNP of > 550 pg / ml
    • 97 % with a BNP of < 550 pg / ml

    Therefore, the BNP value should always be determined in patients with AS.

    Overall it can be said that patients with AS without symptoms have a good prognosis. However, as soon as the patients become symptomatic, the 2-year survival rate without surgical intervention is < 50%. From the onset of symptoms until death it takes a natural course (Kasper 2015):

    • for angina pectoris 3 years
    • Syncopes 3 years
    • Dyspnea 2 years
    • Heart failure 1.5 - 2 years

    The mortality rate for a surgical valve replacement is approximately 3 % and increases to approximately 6 % with simultaneous coronary artery bypass grafting (CABG) (Herold 2018).

    According to the latest guidelines, there is no longer an indication for endocarditis prophylaxis in patients with aortic valve stenosis that has not been treated surgically by then (Herold 2018). The only exception is endocarditis that has already taken place in the medical history (Kasper 2015).

    After valve reconstruction or a prosthetic heart valve, however, there is a significantly increased risk of endocarditis (cave: prophylaxis with medication necessary: the post-procedural bacteremia frequency after tooth extractions in gingivitis is up to 90%. For this reason, endocarditis prophylaxis is necessary postoperatively for certain procedures. The standard therapy is administered as a single dose approx. 30-60 minutes before the procedure, e.g. amoxicillin or ampicillin 2 g orally or i.v., or in the case of penicillin allergy clindamycin 600 mg also orally or i.v. (Pinger 2019).

    For further details see Endocarditis prophylaxis

    Literature
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    1. Anschütz F et al (1974) Paperbacks General Medicine: Cardiology Hypertension Springer Verlag S. 134
    2. Bob A et al (2001) Internal Medicine Dual Series Special Edition MLP Thieme Verlag S 84 - 87
    3. Bonzel T et al (2009) Guideline heart catheter Steinkopff Verlag 54 - 57
    4. Gieretz H G, Ludolph E (2010) Review in Cardiology. ecomed Medicine S 104 - 109
    5. Herrmann S et al (2013) "Low-Flow/Low-Gradient" Aortic Valve Stenosis: Clinical and Diagnostic Spectrum. Heart: Cardiovascular Diseases. (3) Springer Verlag
    6. Herold G et al (2018) Internal Medicine. Herold Publisher S 174- 176
    7. Herold G et al (2019) Internal Medicine Herold Verlag S 177

    8. Ince H et al (2018) Heart valve diseases - Update ESC Guideline 2017 Dtsch med Wochensch (24) Georg Thieme Verlag S 1765 - 1769

    9. Kasper D L et al (2015) Harrison's Principles of Internal Medicine. Mc Graw Hill Education S 1528- 1534
    10. Kasper D L et al (2015) Harrison's Internal Medicine. Georg Thieme Publisher S 1863 - 1883
    11. Krakow I et al (2005) The Cardiac Catheter Book: Diagnostic and interventional catheter techniques. Georg Thieme Publisher 130 - 138
    12. Omran H et al (2003) Silent and apparent cerebral embolism after retrograde catheterisation of the aortic valve in valvular stenosis: a prospective, randomised study. Lancet Elsevier (361) 1241 - 1246
    13. Pinger S (2019) Repetitorium Kardiologie: For clinic, practice, specialist examination. German medical publisher. 275 – 298
    14. Schuler G (2017) Physical activity and illness. De Gruyter Publishing House S 289, S 292

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    Williams-beuren syndrome;

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    Last updated on: 29.10.2020