3D Evaluation of Myocardial Edema: Experimental Study on 22 Pigs Using Magnetic Resonance and Tissue Analysis*

Background: Myocardial edema (ME) adversely affects ventricular function. Thus, we performed an animal study to demonstrate (1) 3D-ME using magnetic resonance imaging (MRI), which can show ME depending on myocardial location, (2) type of cardioplegic solution, and (3) quantification tools. Methods: Pig hearts (n = 22) were perfused using Bretschneider's solution (BRET, n = 8), butanedionemonoxime (BDM, n=8), or no cardioplegia as controls (CTRL, n = 6). Hearts underwent MRI (T₁-inversion recovery). Myocardial water content (MWC, reference method) was determined from left ventricle anterior, posterior (PW), lateral wall, interventricular septum, papillary muscle, right ventricle wall. Images underwent 3D reconstruction using ray-tracing. Gray-value analysis was performed on „virtual” samples. For statistical analysis, ANOVA, Student's t-test, and the Student-Newman-Keuls test were used. Results: (1) ME was induced (p < 0.0001 vs. control). Localization differed in MWC, p = 0.003 (BRET), p = 0.023 (BDM), highest at PW (p < 0.01). (2) Differences between the cardioplegia groups were not significant. (3) “Virtual” samples showed equal distribution (BRET: p = 0.007, BDM: p = 0.003), highest at PW (p < 0.01). Conclusions: We validated 3D assessment of induced ME in pig hearts using MRI. The method may therefore become an exact tool in monitoring cardioplegia.

Myocardial edema - Magnetic resonance tomography - Tissue analysis - Myocardial perfusion - Cardioplegia

References

• 1 Bretschneider H J, Gebhard M M. Significance of myocardial predamage and condition in ischemic tolerance of the heart. In: Minami K, Körfer R, Wada J (eds) Cardio-thoracic surgery - What's new in current practice?. Amsterdam, London, New York, Tokyo; Elsevier 1992: 35-44
• 2 Allen S J, Geissler H J, Davis K L, et al. Augmenting cardiac contractility hastens myocardial edema resolution after cardiopulmonary bypass and cardioplegic arrest.  Anaesth Analg. 1997;  85 987-992
• 3 Amirhamzeh M MR, Dean D A, Jia C X, et al. Iatrogenic myocardial edema: increased diastolic compliance and time course of resolution in vivo.  Ann Thorac Surg. 1996;  62 737-743
• 4 Weng Z C, Nicolosi A C, Detwiler P W, et al. Effects of crystalloid, blood, and University of Wisconsin perfusates on weight, water content, and left ventricular compliance in an edema-prone, isolated porcine heart model.  J Thorac Cardiovasc Surg. 1992;  103 504-513
• 5 Aldea G S, Austin R E, Flynn A E, Coggins D L, Husseini W, Hoffmann J IE. Heterogeneous delivery of cardioplegic solution in the absence of coronary artery disease.  J Thorac Cardiovasc Surg. 1990;  99 345-353
• 6 Meinzer H P, Meetz K, Scheppelmann D, Engelmann U, Baur H J. The Heidelberg Ray Tracing Model. IEEE Comp Graph Appl 1991: 34-43
• 7 Glantz S A. Ein besserer Ansatz für den multiplen Vergleichstest: der Student-Newman-Keuls-Test. In: Heinecke A, Köpcke W (eds) Biostatistik. London; McGraw-Hill 1997: 88-92
• 8 Flynn A E, Coggins D L, Austin R E, et al. Nonuniform blood flow in the canine left ventricle.  J Surg Res. 1990;  49 379-384
• 9 Coggins D L, Flynn A E, Austin R E, et al. Nonuniform loss of regional flow reserve during myocardial ischemia in dogs.  Circ Res. 1990;  67 253-264
• 10 Aldea G S. Complementary use of antegrade and retrograde cardioplegia.  Ann Thorac Surg. 1998;  66 697-698
• 11 Ericsson A B, Takeshima S, Vaage J. Simultaneous antegrade and retrograde delivery of continuous warm blood cardioplegia after global ischemia.  J Thorac Cardiovasc Surg. 1998;  115 716-722
• 12 Vahl C F, Albers J, Makabe M H, et al. Heterogeneity of myocardial edema in isolated pig hearts after perfusion with different types of cardioprotective solutions.  Thorac Cardiovasc Surg. 1998;  46 285-292
• 13 Jayawant A M, Stephenson E R, Damiano R J. 2,3-Butanedione monoxime cardioplegia: advantages over hyperkalemia in blood-perfused isolated hearts.  Ann Thorac Surg. 1999;  67 618-623
• 14 Vogel W M, Cerel A W, Apstein C S. Post-ischemic cardiac chamber stiffness and coronary vasomotion: the role of edema and effects of dextran.  J Mol Cell Cardiol. 1986;  18 1207-1218
• 15 Laine G A, Allen S J. Left ventricular myocardial edema. Lymph flow, interstitial fibrosis, and cardiac function.  Circ Res. 1991;  68 1713-1721
• 16 Takoudes T G, Amirhamzeh M MR, Hsu D T, Wise B R, Odeh S O, Spotnitz H M. Time course of perfusion-induced myocardial edema resolution in rats.  J Surg Res. 1994;  57 641-646
• 17 Mehlhorn U, Davis K L, Burke E J, Adams D, Laine G A, Allen S J. Impact of cardiopulmonary bypass and cardioplegic arrest on myocardial lymphatic function.  Am J Physiol. 1995;  268 178-183
• 18 Mehlhorn U. Improved myocardial protection using continuous coronary perfusion with normothermic blood and beta-blockade with esmolol.  Thorac Cardiovasc Surg. 1997;  45 224-231
• 19 Mehlhorn U, Allen S J, Adams D L, et al. Normothermic continuous antegrade blood cardioplegia does not prevent myocardial edema and cardiac dysfunction.  Circulation. 1995;  92 1939-1946
• 20 Higgins C B, Herfkens R, Lipton M J, et al. Nuclear magnetic resonance imaging of acute myocardial infarction in dogs: alterations in magnetic relaxation times.  Am J Cardiol. 1983;  52 184-188

*This paper was presented at the 3^rd joint meeting of the German, the Austrian and the Swiss Societies for Thoracic and Cardiovascular Surgery, February 9 - 12, Lucerne (P 194, Thorac Cardiovasc Surg 2000, 48 Suppl 1: 145).