1. UNIVERSITY OF SARAJEVO University Clinical Center
Clinic for heart and rheumatic diseases
  AKH, University of Wien, Austria
STRESS ECHOCARDIOGRAPHY
in diagnosis of LOW FLOW - LOW GRADIENT AORTIC STENOSIS
Sokolović S, Mundigler G. Naser N.
V. Kongres Kardiologa & Angiologa BiH, Sarajevo

2. Epidemiology of Aortic Stenosis
AS is common
> age 75: % 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

3. Aortic Stenosis Severity of AS with preserved LV :
Straightforward to evaluate
. Low Flow-Low Gradient AS, with significantly reduced LV :
Dg challenge

4. STRESS TEST Stress modalities: Exercise Sitting bicycle Supine bicycle
Threadmill

5. STRESS TEST Pharmacological Dipyridamole – vasodilating
Adenosine – vasodilating
Dobutamine: as predominantly a B1-adrenergic stimulating agent:Contractility and HR ↑
Dobutamine: plasma half-life about 2 min.

6. DST INDICATIONS Better accuracy than exercise ECG
INDICATION I:
Diagnosis of ischemia:
Better accuracy than exercise ECG
DSE possible in patients unable to exercise

7. DST INDICATIONS 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.

8. DST INDICATIONS Indications II:
Before PCI / CABG: Significance of stenosis. : only most severe stenosis usually responsive
Viability
After PCI / CABG: control for restenosis / graft patency

9. CONTRAINDICATIONS Dobutamine:
Uncontrolled hypertension: >220/120 resting
Known hypertrophic obstructive cardiomyopathy.
Known malignant ventricular arrhythmia
Dipyridamole:
AV-block
COPD
Aminofilin

10. 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

11. 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)

12. 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

13. Diagnostic value OF DST:
Sensitivity: %
If target HR reached
Specificity: 80 – 100 %
Comparable to perfusion scintigraphy

14. 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

15. 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

16. 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

17. 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

18. DOBUTAMIN STRESS ECHO True vs Pseudo-severe AS
.. To differentiate between:
True vs Pseudo-severe AS

19. SEVERE AS . AV area remains almost the same after test
. PG. MPG & PVsignificantly 

20. MILD TO MODERATE AS
All parameters 

21. Pseudo-severe AS: . AVA significantly  (0,3cm2)
. PG, MPG, PV remain more or less constant despite flow improvement

22. INDICATIONS FOR DSE
In symptomatic patient with AS where echocardiography findings during the rest
do not correlate with the symptoms.

23. DSE

24. DSE Fixed low-gradient AS: benefit from valve replacement surgery
pseudo-AS : valve replacement surgery is not indicated

25. 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

26. Results - LV: normal sized
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)

27. Contractility improved in: basal, mid lateral segment
At Peak:
Contractility improved in: basal, mid lateral segment
decreased in: basal segment of anterior septum
. The other LV wall segments: no change after the test
. EF ↑ up to 40%
. PG ↑ 64mmHg, MPG 46mmHg
. EOA ↑ 0,85cm2.(0,42cm2/cm2)
. Pts : free of any symptoms, no any ECG - changes

28. RESULTS Final diagnosis:
Severe aortic stenosis with preserved contractile reserve

29. DECISION
Surgical Valve Replacement

30. CONCLUSION 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.

31. THANK YOU !