Electrophysiological Assessment of Cardiac Complication in Chronic Diabetic Minipigs

Abstract

Abundant evidence shows that patients with type 1 diabetes are at high risk for several cardiovascular disorders. Our objective was to assess cardiac electro-pathophysiology changes linked to chronic insulin-dependent diabetes in the Yucatan miniature swine (total N = 22). Diabetic animals were divided into different groups based on duration of diabetes (Group 1: normal; Groups 2, 3, 4 and 5: diabetes duration of 3-4, 4-5, 5-6 and >6 years). Cardiac electrophysiological parameters were acquired in conscious diabetic and normal control animals using a standard lead II configuration. Routine measurements of electrocardiograms, including HR (bpm), RR, PR, QRS, QT and QTc, were done (all in msec). A heart rate correction for the QT interval (QTc) was calculated using the Fridericia method [QTc=QT/(cubed root of RR)]. Mean heart rate was decreased for the diabetic Groups 2, 4, and 5 compared to the mean heart rate for normal animals (52, 54 and 54 vs. 75 bpm, respectively). The mean PR interval was increased in all diabetic animals compared to normal animals and the effect increase with the duration of diabetes (132 vs. 138, 140, 152 and 172 msec for Groups 1, 2, 3, 4 and 5, respectively). The mean QRS interval was increased for all of the diabetic animals compared to normal animals (47 vs. 56, 66, 52 and 64 msec for Groups 1, 2, 3, 4 and 5, respectively). There were no pronounced QTc abnormalities in this study when comparing diabetic to the normal animals although one animal in Group 3 did have a QTc prolongation of 43 msec. In addition, one animal in Group 5 had a prolonged PR segment (224 msec) associated with frequent ventricular escape complexes. In conclusion, chronic diabetes in Yucatan miniature swine manifests with progressive effects on heart rate, PR interval, and QRS duration. This indicates that the diabetic minipig could provide a good model to test preventative approaches for progressive cardiac therapies in diabetes, using electrocardiography segments as markers of early heart damage. Disclosure A. Stricker-Krongrad: None. J. Liu: None. G. Bouchard: None.