Epidemiology of Aortic Stenosis as is common



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tarix21.04.2017
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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)







  • 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 !




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