Transcript How we do DSMR Viability

How We Do Dobutamine Stress
Magnetic Resonance (DSMR)
Ashraf Hamdan, Ingo Paetsch, Eike Nagel
German Heart Institute Berlin
and
www.cmr-academy.com
Created October 2007 for SCMR
This presentation posted for members of scmr as an educational guide – it represents the views and
practices of the author, and not necessarily those of SCMR.
Purpose
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Detection of myocardial ischemia and viability
Wall motion abnormalities (WMA) are one of
the earliest signs of myocardial ischemia during
stress.
Dobutamine is the preferred pharmacological
stress agent for the detection of inducible
WMA.
How we do DSMR
Stress agents
Dobutamine: i.v, 5mg/ml, max. dose
50µ/kg/min
Atropine: i.v, 0.25 mg fractions, maximal dose 2mg
Antidote:
1.
2.
Esmolol: i.v 0.5mg/kg, additional 0.2 mg/kg as needed
Sublingual nitroglycerine
- Patients should be asked to stop ß-blockers
and nitrates 24 hours prior to the examination
- Patients need to sign informed consent form
How we do DSMR
Contraindications for
Dobutamine/Atropine
1.
2.
3.
4.
5.
6.
7.
Severe arterial hypertension (> 220/120 mmHg)
Unstable angina pectoris
Acute myocardial infarction
Severe aortic stenosis (AVA < 1cm2)
HOCM
Acute Perimyocarditis or Endocarditis
Glaucoma
How we do DSMR
Monitoring requirements
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Heart rate & rhythm: continuously
Blood pressure: every minute
Pulse oximetry: not required when the vector-ECG
used
Symptoms: continuously
WMA: every dose increment
ST-Segment changes are not diagnostic from the
vector-ECG; However, since WMA precede ECGchanges, monitoring is effective without a diagnostic
ECG.
How we do DSMR
Scanner environment
ECG
Line for dobutamine infusion on
one arm
Blood pressure cuff on the other
arm
Two flexible coil elements
(signal receiver) on the
anterior chest. Three
additional coil elements are
integrated in the table
Pulse Oximetry
Trolley under the table
How we do DSMR
Scanner environment
Infusion pump for Dobutamine
infusion
Blood pressure monitor and vector ECG
Cine scans are judged visually in an „automatic view“ window
Visual assessment of left ventricular WMA, the standard
scoring system is applied per myocardial segment (17segment model):
1= normokinesis
2=hypo kinesis
3=akinesis
4=dyskinesis
How we do DSMR
Cine Imaging Technique
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Steady-state free precession (SSFP)
Parallel imaging techniques (SENSE)
Retrograde gating
50 phases/cardiac cycle expiratory breathhold
of approximately 6s possible
Spatial resolution approximately: 1.6X1.6mm
with a slice thickness of 8mm
How we do DSMR
# Rest cine scans in the standard views: apical, mid, and basal short axis views,
4-, 3- and 2-chamber views
# I.v Dobutamine at 3 min stages at doses of 10, 20, 30 and 40 µg/kg/min; all
standard views are acquired at each level
10
3
viability
20
6
30
9
ischemia
How we do DSMR
40
12
(+ Atropin if target heart rate is
not reached)
min
Termination criteria
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Submax. heart rate reached ([220-age] X 0.85)
Systolic RR decrease > 20 mmHg below the
baseline level or decrease > 40 mmHg from a
previous level
RR increase > 240/120 mmHg
Intractable symptoms
New or worsening WMA in n  2 adjacent LV
segments
Symptomatic or complex cardiac tachycardia
How we do DSMR
Side effects during DSMR
Sustained VT
Non-sustained VT
Paroxysmal atrial fibrillation
Transient AV block II 2:1
Severe increase in BP (>240/120)
Decrease in systolic BP>40mmHg
Nausea
1 (0.1%)
4 (0.4%)
16 (1.6%)
2 (0.2%)
5 (0.5%)
5 (0.5%)
31 (3.1%)
Total
64 (6.4%)
Wahl A et al. Eur Heart J 2004; 25:1230-1236
How we do DSMR
Myocardial ischemia
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Ischemia is defined as a new WMA or a biphasic
response.
Overall diagnostic accuracy of DSMR for
detection of WMA is 86%*:
Sensitivity = 86%
 Specificity = 86%
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*Nagel et al. Circulation 1999;99(6):763-70
How we do DSMR
Ischemia
rest
10 µg/kg/min
20 µg/kg
min
30 µg/kg/min
(max)
At rest, no wall motion abnormality. Under high-dose dobutamine up to 30 and 40
µg/kg/min the apical and apico-septal and apico-lateral segments became akinetic
How we do DSMR
Myocardial viability
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Divided into two pathological states:
1.
2.
Myocardial stunning: the result of acute ischemic
insult leading to contractile dysfunction despite
adequate reperfusion
Hibernating myocardium: defined as reversible
left ventricular dysfunction due to chronic
coronary artery disease that improves after
revascularization
How we do DSMR
Viability
rest
10 µg/kg/min
scar
20 µg/kg/min
Improvements of the contractility in anterior and antero-septal
segments under 10 & 20 µg/kg/min dobutamine;
hyperenhancement of 50% in the corresponding segments
How we do DSMR
DSMR: Prognostic value
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The presence of WMA identifies pts at risk of
MI & cardiac death
Pts with neg. DSMR and EF > 40% have low
cardiac event rate, 2% over 2 years
*Hundley et al. Circulation 2002; 106:2328-2333
How we do DSMR
DSMR-Summary
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Can identify ischemic and viable myocardium
Has high sensitivity and specificity
Has relevant prognostic information
Using SSFP and SENSE, DSMR has a high
temporal and spatial resolution
How we do DSMR