Aortic valve insufficiencyI35.1

Aortic valve insufficiency (AI) is the inability to close the semilunar valve located between the aorta and the left ventricle as a result of:

• deformation of the valve
• Prolapse of an aortic valve pocket
• Dilatation of the aortic root
• Destruction of the flap

This leads to a scarred shrinkage of the valve, which ultimately leads to the inability to close the valve. The insufficiency can be acute or chronic.

Pathophysiologically, in aortic valve insufficiency, the inability of the valve to close leads to diastolic backflow of blood into the left ventricle. The resulting increased pendulum volume causes a greater stroke volume and thus leads to a volume load of the left ventricle (LV). In a chronic course, the LV finally dilates and an eccentric left ventricular hypertrophy develops.

Initially the end-diastolic pressure increases only slightly due to the dilatation of the ventricle and the left ventricular hypertrophy can be maintained initially. However, once the heart has reached a certain size, it is no longer possible to maintain the stroke volume and the end-diastolic ventricular pressure and also the end-diastolic ventricular volume increase (Herold 2018). The enlarged heart can take on enormous proportions and, at over 1,000 mg, is one of the heaviest and largest in autopsies (Kasper 2015).

Enlargement of the heart can lead to a compromise of the coronary arteries and thus to myocardial ischemia (Kasper 2015).

In AI, the degree of insufficiency is divided into different scores by expanding the jet. For more details see below under "transthoracic and transesophageal echocardiogram".

A further classification concerns the degree of severity of AI as determined in the angiography:

• Grade I: A short, faint cloud of contrast is visible
• Grade II: There is an increasing reflux of contrast medium, but it does not fill the entire ventricle
• Grade III: This results in a homogeneous, complete but weak staining of the ventricle
• Grade IV: The contrast staining in the ventricle is as strong as in the ascending aorta
• (Apitz 2013)

Acquired aortic valve insufficiency is one of the most common pure valve defects. It occurs more frequently in men than in women (Scherf 1955). Approximately ¾ of patients with isolated aortic valve insufficiency are male (Kasper 2015).

However, congenital isolated aortic valve insufficiency is very rare, as it occurs in the majority of cases together with combined congenital heart defects (Apitz 2013).

Acquired heart valve insufficiency can be triggered by degenerative or inflammatory processes. The following play a special role here::

• coronary heart disease
• cardiomyopathies (both primary and secondary)
• congenital abnormalities

In more than half of the cases, aortic valve insufficiency is caused by dilatation of the aortic root and the ascending aorta. The second most common cause is the bicuspid aortic valve (Schäfers 2004).

Possible causes of acute AI are:

• bacterial endocarditis
• Aortic dissection type A
• Traumas

Possible causes of chronic AI are:

• primarily congenital (bicuspid aortic valve)
• Dilatation of the valve ring
• Dilatation of the aortic root

A dilatation from the age of 60 is mainly caused by arteriosclerosis; otherwise it can still occur in:

• Marfan syndrome
• Ehlers-Danlos Syndrome
• Hurtler Syndrome
• osteogenesis imperfecta
• Syphilis
• Prolapse of an aortic valve pocket
• Lacerations of the aortic valve pocket
• postrheumatic (nowadays only rarely)

Acute progressive form

In the acute form, there is a rapid increase in left ventricular end-diastolic pressure and a consecutive increase in left atrial pressure and pressures in the small circulation (Kasper 2015).

As a result, the following symptoms may develop in the short term (Kasper 2015):

• acute left ventricular decompensation
• acute pulmonary oedema
• cardiogenic shock

Chronic form of the disease

Initially, patients are usually asymptomatic, as the end diastolic pressure increases only slightly at first due to the elasticity of the ventricle and the CPR can be maintained. A mild to moderate form of aortic valve insufficiency can thus show an unremarkable course over decades (Herold 2018).

A typical first symptom is often (Kasper 2015):

• Palpitations (especially when lying down: the lower the frequency, the longer the diastole lasts and the greater the regurgitation volume], but also during excitement)
• increasing left heart failure

In comparison to aortic stenosis, it occurs only rarely (Apitz 2015):

• Cardiac arrhythmias
• Syncopes
• angina pectoris
• sudden cardiac death
• nocturnal and exercise-related dyspnea
• thoracic pain

X-ray thorax:

• Formation of a so-called aortal heart configuration with a large left ventricle protruding to the left
• the left ventricle can extend to the spine in the lateral view (Kasper 2015)
• rounded tip of the heart
• the Cava triangle has passed (Pinger 2019)
• Dilatation and elongation of the ascending aorta
• prominent aortic button (also called the shoe shape of the heart in its pronounced state)
• in stage IV, the left atrium and parts of the right heart may also be enlarged (so-called mitralization of the aortic heart (Gieretz 2010)

With the fluoroscopy you can see:

• a pulsation of the left ventricle and the aorta

Transthoracic and transesophageal echocardiogram (TEE)

Even a minor aortic valve insufficiency can be reliably detected in color Doppler (Gieretz 2010). The so-called AI- Jet (backflow through the aortic valve [Herold 2018]) can be seen.

The semi-quantitative allocation is assigned to the following scores by determining the length and width of the jet at its base (Apitz 2013):

• Score 0:
  • Width < 1.0 cm
  • Length ≤ 2.0 cm
• Score I:
  • Width < 1,5 cm
  • Length ≤ 1/2 LV
• Score II:
  • width < 1,5 cm or > 1,5 cm
  • Length > 1/2 LV < 1.2 LV
• Score III:
  • width > 1,5 cm
  • Length ≥ 1.2 LV
• Score IV:
  • LV filled in

Assignment to one of the 4 degrees of severity is usually already possible with the transthoracic echo. If, however, the sound conditions are limited, a closer differentiation is usually possible with the transesophageal echo (Gieretz 2010).

In the 2D echo the aetiology of the AI can be determined e.g. by:

• Endocarditis
• bicuspid valve replacement therapy
• secondary AI (for aortic aneurysm) etc.
• Semiquantification via proximal jet width
• Assessment of the left ventricle in terms of size and function (crucial for further management)
• Assessment of the pressure conditions in the small circuit
• Assessment of the other flaps

Left heart catheter

Here too, the extent of an insufficiency can be determined and assigned to one of the 4 degrees of severity (Herold 2018). For more information on the classification of the degrees of severity see above under "Classification". Gieretz (2010) considers this examination to be indicated from an expert's point of view only if there is a suspicion of additional CHD. However, the reduced blood supply to the coronary arteries often occurs as a result of the enlargement of the left ventricle and the associated compromise of the coronary arteries from a certain degree of hypertrophy onwards (Kaspar 2015).

CMR (magnetic resonance imaging)

Aortic valve insufficiency can be easily diagnosed by CMR. The diagnostic accuracy is 97 % (Cracow 2005). Anatomical and functional assessment can be made:

• Aortic valve
• left ventricle
• ascending aorta

Furthermore, they can be precisely quantified and also reproduced:

• the volume of insufficiency
• the regurgitation fraction
• (Frick 2018)
• Cine images of the ventricles in long-axis and short-axis geometry allow a precise representation of the ventricular volumes, stroke volume, ejection fraction and dilatation of the left ventricle to be identified and, if necessary, checked later (Frick 2018).

Inspection and palpation

The leading symptoms of AI are:

• large blood pressure amplitude (specific, but not sensitive! see below)
• Pulsus celer et altus (also called water hammer pulse)

The large blood pressure amplitude is caused by:

• the increase of the systolic blood pressure due to the large stroke volume
• the decrease of the diastolic value as a wind boiler effect due to the blood reflux.

However, due to increased peripheral vascular resistance (e.g., in elderly patients), the large blood pressure amplitude may be absent - even in severe aortic valve regurgitation (Herold 2018). In addition, there may be:

• conspicuously pale skin
• The cardiac apex may be hyperdynamic, downward outward, and widened in eccentric left ventricular hypertrophy

Due to the large blood pressure amplitude, the following pulsatory phenomena may occur:

• visible pulsations of the carotids (so-called Corrigan's sign)
• pulse-synchronous droning in the head
• pulse-synchronous nodding of the head (so-called de Musset's sign)
• capillary pulse visible after light pressure on a fingernail (so-called Quincke sign)
• pulse-synchronous pulsations of the uvula (so-called Müller sign)
• systolic blood pressure in the lower extremities is > 60 mmHg higher than in the upper extremities (so-called Hill phenomenon)

Auscultation

On auscultation, the following phenomena are typically found:

• immediately after the 2nd heart sound, a diastolic decrescendo murmur occurs, described as breathy or pouring and of high frequency. The murmur is best heard over Erb's point (3rd ICR left parasternal) or over the aorta and with the patient bent forward.
• regularly, a spindle-shaped systolic occurs as a volume murmur due to relative aortic stenosis, the cause of which is the disproportion between a normally large valve opening but an enormously large stroke volume
• a rumbling late diastolic phenomenon (the so-called Austin- Flint noise) occurs only occasionally. It results from obstruction of the opening of the anterior mitral leaflet by diastolic blood reflux.
• over the femoral arteries are heard:
  • a simple loud sound (the so-called gunshot phenomenon)
  • due to the strong systolic-diastolic pressure fluctuations, there are vibrations of the vessel walls, which can be heard in systole as well as in diastole (so-called Traube's double tone)
  • with stronger pressure on the femoral artery, the so-called Duroziez double tone develops from Traube's double tone (Hochrein 1959)

ECG

Typical signs of aortic valve insufficiency in the ECG are (Klinge 2002):

• Signs of left hypertrophy with
  • Sokolow index or index of the horizontal plane (SV1 + RV5 or V6 > 3.5 mV)
  • Lewis index or frontal plane index (RI + S III - R III - SI = > + 1.6 mV)
• accentuated Q- jags
• T- negatives (in contrast to pressure hypertrophy in e.g. aortic stenosis, these occur late)

Severe aortic valve insufficiency can cause irreversible damage to the myocardium, which - even after successful valve replacement therapy - can persist and lead to progressive heart failure. For this reason, surgical intervention should be carried out in good time, i.e. depending on the limits for ventricular size and function and not primarily on the patient's symptoms (Herold 2018).

Therapeutic measures:

• Patients with acute aortic valve insufficiency must be immediately admitted to a surgical procedure (Kasper 2015)
• in the case of a chronic course, an operation is indicated as soon as the patient becomes symptomatic (see below); the operation can be planned
• asymptomatic patients with hemodynamically effective aortic valve insufficiency should remain physically active but avoid competitive sports and strenuous exercise
• Treatment of existing left heart failure in patients who are not candidates for surgery
• endocarditis prophylaxis is - according to current guidelines - no longer recommended for patients who have not yet been operated on

The surgical measure consists either of a complete replacement of the defective valve, which is mostly performed, or a - rarely performed - valve reconstruction (e.g. in case of aorticectasia or aneurysm as the cause of AI).

The indication and the evidence level for surgical intervention of severe AI according to ESC Guidelines 2012 are:

1. symptomatic patients with exercise dyspnea starting with NYHA II or with angina pectoris (IB)

2. asymptomatic patients with EF < 50 % (IB)

3. asymptomatic patients with an EF > 50 % and an LV diameter enddiastolic (EDD) > 70 mm (IIaB)

- asymptomatic patients with an EDD > 50 mm (IIaB)

(Herald 2019)

The indication for surgery is independent of the severity of the aortic dilatation:

- in patients with Marfan syndrome with ascending aorta ≥ 50 mm (IC)

- in patients with Marfan syndrome of similar disease of the ascending aorta ≥ 45 mm (IIaC)

- for bicuspid aortic valve and ascending aorta ≥ 50 mm (IIaC)

- other patients with ascending aorta ≥ 55 mm (IIaC)

- Existing indication for aortic valve surgery and aortic valve replacement from ≥ 45 mm (IIaC)

(Herald 2019)

Gravidity: If aortic valve insufficiency is diagnosed during pregnancy, conservative treatment with diuretics and hydralazine is sufficient in most cases. However, in case of refractory heart failure from stage III - IV, surgery should be performed (Pinger 2019).

Basically, it can be said that in valve insufficiency, the resulting volume load, which leads to eccentric hypertrophy, has a more favourable prognosis compared to a pressure load with concentric hypertrophy (Herold 2018).

Natural course:

In the diagnosis of asymptomatic aortic valve insufficiency the

10- Annual survival rate:

• 90 % for a mild to moderate AI
• 50 % for higher grade AI
• Patients who already have symptoms have a less favourable prognosis

Without therapeutic intervention, the mean survival time is:

• simultaneous angina pectoris is 5 years,
• existing heart failure at 2 years (Herold 2018).

If higher-grade aortic valve insufficiency persists for a longer period, irreversible damage to the myocardium occurs. This damage can persist even after successful valve replacement therapy and lead to progressive heart failure (Herold 2018).

In all other cases, it is to be expected that radiological normalisation of the heart shadow is present within the first 6 months after the operation (Gieretz 2010).

The mortality rate of a valve replacement operation for aortic valves is approx. 3 %. If coronary artery bypass surgery (CABG) is performed at the same time, the mortality rate is approx. 6 % (Herold 2018).

Patients with valve reconstruction or prosthetic heart valve have a significantly increased risk of endocarditis. The post-procedural bacteremia frequency after tooth extractions in gingivitis is up to 90 %. For this reason, postoperative endocarditis prophylaxis is necessary 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

Progress reviews are mandatory:

• intervals of 12 months in asymptomatic patients with preserved systolic ventricular function and a diameter of the left ventricle (LVESD) < 50 mm and stable values in repeated measurements

Intervals of 3 - 6 months for:

• higher degree changes and significant dynamics of findings compared to the last control

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