Epidemiology of Aortic Stenosis as is common

Epidemiology of Aortic Stenosis

• AS is common

• > age 75: 3% SAA

• Long asymptomatic phase: risk of sudden death low

• Mortality ↑: exertional chest pain, syncope, breathlessness

• Mortality up to 12% soon after onset of symptoms

• Significant AS and LV dysfunction: poor prognoses

Severity of AS with preserved LV :

• Severity of AS with preserved LV :

• Straightforward to evaluate

• . Low Flow-Low Gradient AS, with significantly reduced LV :

• Dg challenge

STRESS TEST

• Stress modalities:

• Exercise

• Sitting bicycle

• Supine bicycle

• Threadmill

Pharmacological

• Pharmacological

• Dipyridamole – vasodilating

• Adenosine – vasodilating

• Dobutamine: as predominantly a B1-adrenergic stimulating agent:Contractility and HR ↑

• Dobutamine: plasma half-life about 2 min.

DST INDICATIONS

• INDICATION I:

• Diagnosis of ischemia:

• Better accuracy than exercise ECG

• DSE possible in patients unable to exercise

After AMI:

• After AMI:

• Early wall motion abnormality predicts new event

• Remote wall motion abnormality predicts multivessel disease.

• Viability of akinetic area:

• Sustained improvement: Good prognosis

• Biphasic response: Good prognosis with revascularisation, poor without.

Indications II:

• Indications II:

• Before PCI / CABG: Significance of stenosis. : only most severe stenosis usually responsive

• Viability

• After PCI / CABG: control for restenosis / graft patency

CONTRAINDICATIONS

• Dobutamine:

• Uncontrolled hypertension: >220/120 resting

• Known hypertrophic obstructive cardiomyopathy.

• Known malignant ventricular arrhythmia

• Dipyridamole:

• AV-block

• COPD

• Aminofilin

TECHICAL REQUIREMENTS

• Personnel requirement: doctor and nurse minimum.

• Patient fasting for 2 hours previously

• Basic and advanced CPR available

• Beta blockers discontinued for at least 24 hours

• ECG & blood pressure monitoring

• Echocardiography: continuous monitoring.

• Recording of cine loops at baseline, low dose, high dose, and recovery (optional)

• Record 3 cycles

TERMINATION

• Side-by side comparison: Termination criteria:

• Positive finding by echo: New wall motion abnormality

• ST depression > 3 mm

• BP limits:

• > 220/120

• < 70/systolic if good ventricular function

• any BP drop > 100 mmHg if poor or reduced LV function

• Arrhythmia: Non-sustained VT or sustained SVT

• Intolerable symptoms (Angina, nausea)

• Target Heart rate (> 85% of 220 -age)

• Maximum dose (40 µg/kg/min + up to 1 mg atropine)

Positive stress echo test:

• .1 segment with new a-or dyskinesia or

• . 3 segments with new hypokinesia

• (= WMSI > 1.25 or increase by 0.25)

• Additional criteria:

• Post-systolic thickening

• Diastolic abnormalities

Diagnostic value OF DST:

• Sensitivity: 80 -90%

• If target HR reached

• Specificity: 80 – 100 %

• Comparable to perfusion scintigraphy

Definition of LF-LG AS

• Low gradient AS as severe aortic stenosis (valve area <1.0 cm2) with a transvalvular PG <30 mmHg

• Low gradient AS occurs in LV systolic dysfunction with low EF, which results in low flow rate across AV

• Contractile reserve: the ability to increase transvalvular flow and not defined by an improvement in wall motion score or EF

LF-LG AS

• Low gradient AS: a) caused by critical AS causing LV impairment (fibrosis)

• b) moderate AS coexisting with another cause of LV impairment: CAD, alcohol, cardiomyopathy

• The main challenges:

• - to differentiate these two states

• - to determine whether the LV is likely to recover after AV surgery

Epidemiology

• Difficulty to assess true severity of stenosis at low CO

• PG & calculated AVA flow-dependent

• LV dysfunction: Presence of low flow rather than significant valve disease

• Morbidity & Mortality LG AS + low EF, A. surgery is consid

• 50% do not survive or post op persistent symptoms

• > 600 AS, pts. >125 mmHg = best postop. survival, pts MPG <35 mmHg had worst (Lund, Circulation)

• The risk is increased with CAD

DOBUTAMIN STRESS ECHO TEST

• Assess aortic stenosis with poor LV function

• Generally low gradient and low area with low dose D

• Increase in gradient: significant AS

• increase in aortic valve area: poor hemodynamics

• non-significant AS

• Continuous infusion up to 20mcg/kg/min

.. To differentiate between:

• .. To differentiate between:

• True vs Pseudo-severe AS

. AV area remains almost the same after test

• . AV area remains almost the same after test

• . PG. MPG & PVsignificantly 

• All parameters 

. AVA significantly  (0,3cm2)

• . AVA significantly  (0,3cm2)

• . PG, MPG, PV remain more or less constant despite flow improvement

In symptomatic patient with AS where echocardiography findings during the rest

• In symptomatic patient with AS where echocardiography findings during the rest

• do not correlate with the symptoms.

DSE

Fixed low-gradient AS: benefit from valve replacement surgery

• Fixed low-gradient AS: benefit from valve replacement surgery

• pseudo-AS : valve replacement surgery is not indicated

Patients and Method

• A male 62 y/o, at least moderate AS with low flow and low TG

• 72 kg, 172cm, BSA 1,86cm2,

• DST starting: 2,5mcg/kg/min increasing at 3 min.intervals to 5, 10, 15 and 20 mcg/kg/min

• Monitoring: 12-lead ECG, RR

Results

• At rest
• - LV: normal sized

• - Akinesis: apical anteroseptal, inferoapical, posterorolateral, mid segment of anteroseptal

• - Hypokinesis: basal and mid posterior, inferior and lateral

• - EF : 33%

• - PG: 55mmHg, MPG: 35mmHg

• - EOA: 0,8cm2. (0,4cm2/cm2)

• Final diagnosis:

• Severe aortic stenosis with preserved contractile reserve

• Surgical Valve Replacement

Dobutamin Stress Echocardiography:

• Dobutamin Stress Echocardiography:

• - Relevant Dg info in AS of unclear significance & reduced LV function

• - Better outcome if management decisions based on the result of DST

• - Moderate AS after DSE: conservative th.

THANK YOU !