1. How We Do Dobutamine Stress Magnetic Resonance (DSMR)
Ashraf Hamdan, Ingo Paetsch, Eike Nagel
German Heart Institute Berlin
and
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.

2. Purpose 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.

3. Stress agents Dobutamine: i.v, 5mg/ml, max. dose 50µ/kg/min Antidote:
Atropine: i.v, 0.25 mg fractions, maximal dose 2mg
Antidote:
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

4. Contraindications for Dobutamine/Atropine
Severe arterial hypertension (> 220/120 mmHg)
Unstable angina pectoris
Acute myocardial infarction
Severe aortic stenosis (AVA < 1cm2)
HOCM
Acute Perimyocarditis or Endocarditis
Glaucoma

5. Monitoring requirements
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 ECG-changes, monitoring is effective without a diagnostic ECG.

6. Blood pressure cuff on the other arm Trolley under the table
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

7. 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 (17-segment model):
1= normokinesis
2=hypo kinesis
3=akinesis
4=dyskinesis

8. Cine Imaging Technique
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

9. 9 12 min 6 viability ischemia
# 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
(+ Atropin if target heart rate is not reached) 6 9 12 3
min
viability
ischemia

10. Termination criteria 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

11. Side effects during DSMR
Sustained VT (0.1%)
Non-sustained VT (0.4%)
Paroxysmal atrial fibrillation 16 (1.6%)
Transient AV block II 2: (0.2%)
Severe increase in BP (>240/120) 5 (0.5%)
Decrease in systolic BP>40mmHg 5 (0.5%)
Nausea (3.1%)
Total (6.4%)
Wahl A et al. Eur Heart J 2004; 25:

12. Myocardial ischemia
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%
*Nagel et al. Circulation 1999;99(6):763-70

13. 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

14. Myocardial viability Divided into two pathological states:
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

15. Viability rest scar 10 µg/kg/min 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

16. DSMR: Prognostic value
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:

17. DSMR-Summary 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