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Transcript
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 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 1. 2. 3. 4. 5. 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 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 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 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 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 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 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 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