Signs in vector-electrocardiography (VECG) predicting the fibrillatory propensity of iodixanol and mannitol solutions after injection into the left coronary artery of pigs.

RATIONALE AND OBJECTIVES: To find signs in vector-electrocardiography (VECG) predicting the ventricular fibrillatory propensity (VF-PROP) of iodixanol and mannitol solutions after injection into the left coronary artery (LCA) of pigs. MATERIALS AND METHODS: Five plasma-isotonic solutions perfused LCA: Iod 320 + Na/Ca (iodixanol 320 mg I/mL, 19 mM NaCl, 0.3 mM CaCl(2)), Iod 320 + Mann (iodixanol 320 mg I/mL, 50 mM mannitol), Mann + Na/Ca (240 mM mannitol, 19 mM NaCl, 0.3 mM CaCl(2)), Mann (275 mM mannitol), and Ringer (representing "physiologic electrolytes"). The first two solutions have at 37 degrees C viscosity 13 mPas and the others <1 mPas. In eight pigs, 20 mL of each solution was injected twice for 10 seconds, and in 15 pigs, each solution was injected for 11-40 seconds (0.5 mL/second) through a wedged catheter in the LCA. If ventricular fibrillation (VF) occurred, injection was stopped and heart was defibrillated. If VF did not occur, perfusion period was 40 seconds. A higher frequency of VF and a shorter period from start of injection until start of VF gave a solution a higher ranking of VF-PROP. RESULTS: The 10-second injections caused no VF. Ringer and Iod 320 + Na/Ca caused no VF after 40-second injections, whereas the other solutions caused VF. Ranking the solutions from lowest to highest VF- PROP gave: Ringer = Iod 320 + Na/Ca < Iod 320 + Mann < Mann + Na/Ca < Mann. Prolongation of QRS time and QTc time were the only VECG signs that showed significant differences (P < .05) between all solutions and correctly ranked the VF-PROP of all solutions in both animal groups. CONCLUSION: The results fit with the concept that a more physiologic electrolyte composition and a higher viscosity of a test solution will, after start of injection of that solution into LCA, delay changes in the electrolyte composition in myocardial interstitial fluid and also delay start of VF. If a plasma isotonic contrast medium (CM) with lower viscosity than that of iodixanol at 320 mgI/mL were created, we conclude that such a CM should have electrolyte composition closer to that of Ringer than present composition (19 mM NaCl and 0.3 mM CaC1(2)) to counteract the effects of faster diffusion of nonphysiologic electrolyte composition from the low-viscosity CM to myocardial interstitial fluid.

Adding sodium and calcium ions to the contrast medium iodixanol reduced the risk of ventricular fibrillation during perfusion of the left coronary artery in pigs: effects of electrolytes, viscosity, and chemotoxicity of an isotonic perfusate.

RATIONAL AND OBJECTIVES: The effects of electrolytes, viscosity, and chemotoxicity of a plasma-isotonic iodine contrast medium iodixanol were compared with regard to its propensity to cause ventricular fibrillation (VF). MATERIALS AND METHODS: The left coronary artery of pigs was perfused with five isotonic solutions: iodixanol 320 mg I/mL with 19 mmol/L NaCl + 0.3 mmol/L CaCl2, Iod 320+Mann (iodixanol 320 mg I/mL + 50 mmol/L mannitol), Mann+Na/Ca (240 mmol/L mannitol with 19 mmol/L NaCl + 0.3 mmol/L CaCl2), Mann (275 mmol/L mannitol) and Ringer. The first two solutions have at 37 degrees C a viscosity of approximately 13 mPa x s while the others have a viscosity < 1 mPa x s. In eight pigs, each test solution was injected twice into the left coronary artery in random order for 10 seconds (injection volume, 20 mL). In 15 pigs, each of the solutions was injected in random order for 11-40 seconds through the end-hole of a wedged 5F balloon catheter in left coronary artery. Injection rate was 0.5 mL/sec until VF occurred. If VF occurred, injection was stopped and the heart was defibrillated. If VF did not occur, the perfusion period was 40 seconds. RESULTS: The 10-second perfusions caused no VF. The 40-second perfusions with iodixanol 320 mg I/mL with 19 mmol/L NaCl + 0.3 mmol/L CaCl2 or Ringer caused no VF (0%). Iod 320+Mann caused nine VF (60%) after 35 +/- 4 seconds (SEM). Mann+Na/Ca caused 14 VF (93%) after 30 +/- 2 seconds. Mann caused 15 VF (100%) after 24 +/- 2 seconds. Iodixanol 320 mg I/mL with 19 mmol/L NaCl + 0.3 mmol/L CaCl2 and Ringer caused fewer VF than all other solutions (P < .05-.001). Iod 320+Mann caused fewer VF than Mann (P < .05). Iod 320+Mann caused VF later than Mann+Na/Ca or Mann (P < .02 and P < .01). Mann+Na/Ca caused VF later than Mann (P < .05). CONCLUSION: The results fit with a concept that VF starts when the electrolyte composition of the interstitial fluid in the myocardium is sufficiently nonphysiologic. The more physiologic the electrolyte composition of the perfusion fluid, and the higher its viscosity, the slower the composition of the interstitial fluid will be changed, and VF will occur later (or not at all).