Presentation on theme: "Myocardial Viability Thomas H. Hauser MD, MMSc, MPH, FACC"— Presentation transcript:
1 Myocardial Viability Thomas H. Hauser MD, MMSc, MPH, FACC A major teaching hospital of Harvard Medical SchoolMyocardial ViabilityThomas H. HauserMD, MMSc, MPH, FACCDirector of Nuclear CardiologyBeth Israel Deaconess Medical CenterInstructor in MedicineHarvard Medical SchoolBoston, MA
9 Clinical Data58 year-old man with diabetes, hypertension, chronic renal insufficiency, tobacco use, prior heroin abuse and liver transplantation two years ago due to hepatitides B and C.One week prior to admission he was admitted to another hospital with community acquired pneumonia. He was discharged two days prior to admission.He presented on the day of admission with chest pain for 12 hours. In the ER he was noted to have anterior ST elevation.
15 Clinical DataHe was referred for surgical revascularization. The surgical team requested evaluation of myocardial viability given his delayed presentation and the concern for limited myocardial salvage.
16 Stress Protocol Dobutamine at 5 mcg/kg/min was infused for 21 minutes. HR 64 66SBP 124 134No symptomsNo ECG changes
18 Should our patient be revascularized? Clinical DataShould our patient be revascularized?
19 Dysfunctional but Viable Myocardium LVEF 32%LVEF 54%Horn HR, Teichholz LE, Cohn PF, Herman MV, Gorlin R. Augmentation of left ventricular contraction pattern in coronary artery disease by an inotropic catecholamine: the epinephrine ventriculogram. Circulation 1974;49:
20 Dysfunctional but Viable Myocardium HibernatingChronic ischemia or repetitive stunningUltrastructural changes that result inDisassembly of contractile apparatusRecovery in weeks or months after revascularizationStunnedAcute ischemiaNo ultrastructural changesRecovery in minutes to days after revascularization
21 CABG in Patients with LV Dysfunction Chareonthaitawee et al, JACC 2005;46:567
22 Importance of Viable Myocardium J Am Coll Cardiol 2002;39:1151
23 Evaluation of Viability Chareonthaitawee et al, JACC 2005;46:567
24 Nuclear Techniques SPECT PET 201Tl 99mTc 123I Fatty Acids PET Agents 18FDG11C Acetate
25 SPECT 201Tl most commonly used Several protocols for use Stress – redistributionRest – redistributionUsually imaged 4 to 24 hours after initial injectionWith or without reinjectionUsually at 4 hoursPerfusion tracer initiallyIschemia is a sign of viabilityMembrane integrity tracer in the late phaseK analogAssesses integrity of membrane and Na-K-ATPase
26 SPECT 99mTc also helpful PET agents act as with PET imaging Stress – rest protocolPerfusion tracerIschemia is a sign of viabilityMembrane integrity tracerTrapped by active mitochondriaPET agents act as with PET imaging
27 201Tl Uptake and Recovery of Function Perrone-Filardi P, Pace L, Pratarto M, et al. Dobutamine echocardiography predicts improvement of hypoperfused dysfunctional myocardium after revascularization in patients with coronary artery disease. Circulation ;91:
28 Comparison of 201Tl and 99mTc Udelson JE, Coleman PS, Metherall J, et al. Predicting recovery of severe regional ventricular dysfunction. Comparison of resting scintigraphy with 201Tl and 99mTc-sestamibi. Circulation ;89:
29 PETAll PET agents (18FDG, 11C acetate) assess cardiac energy metabolism.18FDG imaging assesses glucose metabolismIschemic myocardium generally favors glucose utilization11C acetate imaging assesses lipid metabolism
33 Importance of Good Patient Preparation In the assessment of myocardial viability, the quality and utility of the images is highly dependent on appropriate patient preparationInadequate patient preparation can lead to spurious results or images with no diagnostic value
34 Myocardial Energy Metabolism Cardiac myocytes are continuously activeRequire efficient use of energy resourcesRequire continual repletion of energy substratesFaced with varying levels in supplyFlexibility in substrate use
35 Anaerobic Metabolism Inefficient Requires glucose Each glucose molecule yields two ATPRequires glucoseDoes not require oxygenLactate is the waste productBased on Autumn Cuellar (Bioengineering Institute, University of Auckland)
36 Aerobic Metabolism Efficient Can function with multiple substrates Citric acid cycle produces abundant ATPCan function with multiple substratesRequires oxygenWater and CO2 are the waste productsBased on Autumn Cuellar (Bioengineering Institute, University of Auckland)
37 Myocardial Energy Metabolism ketone bodiesamino acidsBased on Autumn Cuellar (Bioengineering Institute, University of Auckland)
38 Myocardial Energy Metabolism ketone bodiesamino acidsBased on Autumn Cuellar (Bioengineering Institute, University of Auckland)
39 Glucose HandlingLargely determined by the availability of glucose in the blood streamInsulin is the major regulatory hormone
49 Glucose HandlingIn normal patients, feeding causes a rise in glucose and insulin that restores glucose balanceUptake of glucose in peripheral tissuesHEARTIn type 1 diabetics, feeding causes a rise in glucose while insulin remains low/absentContinued gluconeogenesis and glucose conservationIn type 2 diabetics, feeding causes a rise in glucose and insulin but peripheral tissues are resistant to the action of insulin
54 Acipimox Potent inhibitor of peripheral lypolysis Drastically reduces FFA in bloodAs FFA are the principal alternative energy source for the myocardium, glucose utilization increasesRelatively independent of insulin and glucose levelsNot FDA approvedUsed in Europe
55 Hyperinsulinemic/Euglycemic Clamp Simultaneous infusions of insulin and glucose to increase the insulin level while keeping the glucose level from fallingHigh insulinNormal glucoseLow FFAHigh myocardial glucose utilization
56 Glucose Loading Provide a large dose of oral or IV glucose Endogenous production of insulinSupplemented with exogenous insulin if neededModerately high insulinNormal glucoseLow FFAHigh myocardial glucose utilization
57 Glucose Loading: Diabetes Exogenous insulin is required for appropriate patient preparation with either type 1 or type 2 diabetesWith type 1, there is little or no endogenous insulinWith type 2, there is insulin resistance, requiring higher insulin levels to ensure that insulin has an effectObservation of a falling blood sugar after hyperglycemia is evidence of insulin action
59 Insulin Many different kinds of insulin with varying pharmacokinetics RegularNPHLisproLenteUltralenteGlargineAspartPharmocokinetics also vary with the route of administration
60 InsulinFor patient preparation for FDG imaging, use REGULAR insulin given IVPeak action of subcutaneous regular insulin occurs ~3 hours after the dosePeak action of IV regular insulin occurs ~15 minutes after the dose
62 PET: 18FDGSrinivasan G, Kitsiou AN, Bacharach SL, et al. [18F]Fluorodeoxyglucose Single Photon Emission Computed Tomography : Can It Replace PET and Thallium SPECT for the Assessment of Myocardial Viability? Circulation ;97:
63 PET: 18FDGSrinivasan G, Kitsiou AN, Bacharach SL, et al. [18F]Fluorodeoxyglucose Single Photon Emission Computed Tomography : Can It Replace PET and Thallium SPECT for the Assessment of Myocardial Viability? Circulation ;97:
64 Case 245 year-old man with a history of CAD, diabetes, CHF (LVEF 25%) who presented with repetitive ICD firing due to recurrent VT.He was admitted to the hospital and found to have a small NSTEMI. Cardiac catheterization was performed and showed a 70% proximal LAD stenosis, a totally occluded RCA, and occluded SVGs to the LAD and PDA.
65 Case 2The clinical team determined that his recurrent VT was most likely to ischemia and consulted the CT surgeons to determine his candidacy for a second CABG. The surgeons requested a myocardial viability study prior to proceeding.
67 Case 2The study was interpreted as showing non-viability of the apex and inferior wall. The remaining segments were viable.He subsequently underwent LAD stenting and has done well since then.
68 Case 3A 59 year old with a history of diabetes, hypertension and dyslipidemia sees his PCP because of the new onset of dyspnea. His ECG reveals LBBB. His PCP sends him for nuclear imaging with exercise stress. During the test, he has dyspnea at a low workload.
72 Case 3He is referred for cardiac catheterization, which reveals severe three vessel disease. The consulting cardiac surgeon asks for a determination of myocardial viability before proceeding with surgical revascularization.What can we do to further determine myocardial viability?FDGDelayed enhancement MR
73 Gd Contrast Kinetics in Myocardium Circulation, Dec 1996; 94:
74 Delayed Contrast Enhancement: Bright is Dead Circulation, Nov 1999; 100:
75 Prediction of Recovery of Function N Engl J Med 2000; 343:
82 Comparison of FDG and DE-CMR Knuesel et al. Circulation. 2003;108:1095
83 Spatial Resolution/Scar Imaging Wagner et al. Lancet. 2003;361:374
84 FDG and MR for Scar/Viability Images viable myocardiumDirectly assesses metabolismEstablished gold standard for determining recovery of function after revascularizationDE-CMRImages both scar and viable myocardiumDirectly assesses anatomyBecoming clinically establishedImproved spatial resolution compared to FDG
85 Dobutamine CMRMandapaka et al, J. Magn. Reson. Imaging 2006;24:499–512.
86 Comparison of Techniques CMRSPECT with 18FDGChareonthaitawee et al, JACC 2005;46:567
87 Summary SPECT PET CMR Tl-201 Tc-99m FDG Late gadolinium enhancement Dobutamine