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How We Do Dobutamine Stress Magnetic Resonance (DSMR)

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

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How We Do Dobutamine Stress Magnetic Resonance (DSMR)

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  1. 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.

  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 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. 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. # 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) 9 12 6 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 1 (0.1%) Non-sustained VT 4 (0.4%) Paroxysmal atrial fibrillation 16 (1.6%) Transient AV block II 2:1 2 (0.2%) Severe increase in BP (>240/120) 5 (0.5%) Decrease in systolic BP>40mmHg 5 (0.5%) Nausea 31 (3.1%) Total 64 (6.4%) Wahl A et al. Eur Heart J 2004; 25:1230-1236

  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 10µg/kg/min 20µg/kgmin 30µg/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 10µg/kg/min scar 20µg/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; 106:2328-2333

  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

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