ADULT ECHOCARDIOGRAPHY Lecture Five - PowerPoint Presentation

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ADULT ECHOCARDIOGRAPHYLecture FiveThe Aortic Valve

Harry H. Holdorf PhD, MPA, RDMS, RVT, LRT, N.P.

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Aortic StenosisEtiology

Calcific/degenerative (50% start as bicuspid)

Rheumatic (Assoc. w/mitral stenosis)

Congenital (bicuspid (1-2% of the population), membrane

Supra and subvalvular obstructions

Prosthetic valve dysfunction

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PathophysiologySystolic pressure overload leads to LVH (increase in afterload)Increase in LVEDP leading to increased LA pressure

Ventricular dysfunction may develop late in disease course

Increased risk for endocarditis

Aortic sclerosis occurs when there is Valvular thickening but no hemodynamic gradient

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Physical signsSymptoms of angina, dyspnea and syncope/sudden deathHarsh systolic ejection murmur right upper sternal border (RUSB) crescendo-decrescendo

Decreased or absent A

2 (valve doesn’t move)

Decreased and delayed carotid upstroke with bruit/thrill transmitted from AoV

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Echo (Valvular)Thickened aortic leafletsDecreased valve opening

Post-stenotic dilatation of the aorta-thought to be caused by abnormal turbulence and wall stress (remember that there is low pressure in the aorta (systolic BP) but high pressure in the LV)

Left ventricular hypertrophy

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A secondary finding in aortic stenosis is?Left ventricular hypertrophyIn aortic stenosis, is pulse pressure wide or narrow?

Narrow (pulse pressure is the difference between systolic and diastolic pressures-it is wide in AI and narrow in AS.

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AHC/ACC Guidelines for Aortic Stenosis severity:

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ECHO (BICUSPID)Possible eccentric closure on M-Mode (25% will have normal midline closure)

Thickened aortic leaflets (may be mild)

Systolic doming on LAX view

Bicuspid orifice in SAX view (football)

Check for coexisting Coarctation of the aorta

Left ventricular hypertrophy

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M-mode of a bicuspid aortic valve

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2D bicuspid aortic valve

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NOTE:The best view to diagnose a bicuspid aortic valve is the parasternal:Short-axis systole

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Aortic CoarctationNOTE: Systemic hypertension is a common symptom of aortic

C

oarctation.

Normal descAo velocity is about 1 m/sec

ECHO (FIXED SUBVALVULAR)

Congenital membrane or ridge in LVOT beneath AoV

Early systolic closure or aortic leaflets

Left ventricular hypertrophy

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Sub-aortic membrane

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Echo (Supra-valvular)

Discrete narrowing of aortic root or ascending aorta

Left Ventricular hypertrophy

Doppler

Use PEDOFF probe & multiple windows (suprasternal , apical, right parasternal)

Increased velocity and turbulence at level of obstruction (valvular, subvalvular, supra-valvular)

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Measure peak and mean gradients (take the highest)Use continuity equation for valve area if possible.Use pulsed/color flow Doppler to locate level of obstruction

Mean Doppler and cath gradients correlate better than peak vs. peak to peak

NOTE: What is Takayasu’s arteritis?

Also called aortic arch syndrome, this disease occurs more in young women from Asia. There is fibrosis of the arch and descending Ao of unknown etiology. In advanced states, multiple coarctations may occur (look for supra-valvular AS)

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NOTE:Patients BP = 110/84 Aortic velocity is 5 m/sec. Peak LV pressure in this patient is?

210 mm Hg

Add the Ao gradient 100 mmHg if the velocity is 5 m/sec to the systolic BP.

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Aortic Valve AreaNormal 3.0 – 4.0 cm sq.

Mild >1.5 cm sq.

Mod 1.5 – 1.0 cm sq.

Sev <1.0 cm sq.

NOTE:

The normal aortic valve area is 3-4 cm sq.

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Aortic valve area calculation is an indirect method of determining the area of the aortic valve. The calculated aortic valve orifice area is currently one of the measures for evaluating the severity of aortic stenosis. A valve area of less than 0.8 cm² is considered to be severe aortic stenosis

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There are many ways to calculate the valve area of aortic stenosis. The most commonly used methods involve measurements taken during echocardiography. For interpretation of these values, the area is generally divided by the body surface area, to arrive at the patient's optimal aortic valve orifice area

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The continuity equation states that the flow in one area must equal the flow in a second area if there are no shunts between the two areas. In practical terms, the flow from the left ventricular outflow tract (LVOT) is compared to the flow at the level of the aortic valve. In echocardiography the aortic valve area is calculated using the velocity time integral (VTI) which is the most accurate method and preferred. The flow through the LVOT, or LV Stroke Volume (cm3 or cc), can be calculated by measuring the LVOT diameter (cm), squaring that value, multiplying the value by 0.78540 giving cross sectional area of the LVOT (cm2)and multiplying that value by the LVOT VTI(cm), measured on the spectral Doppler display using pulsed-wave Doppler. From these, it is easy to calculate the area (cm2) of the aortic valve by simply dividing the LV Stroke Volume (cm3) by the AV VTI(cm) measured on the spectral Doppler display using continuous-wave Doppler

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Continuity Equation

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Continuity equationNOTE: Using the continuity equation, when would the severity of AORTIC STENOSISS be underestimated?

LVOT is measured too large

NOTE: Measure LVOT during systole at the leaflets insertion level (Same place as sample position for PW Doppler)

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Describing Severe Aortic Stenosis1

st

Look at Valve area

2

nd

look at Max Gradient (If Valve areas are equal)

3

rd

Look at wall thickness (evidence of LVH)

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Aortic stenosis severity

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Next Lesson: The pulmonic valveLesson Five Completed