ABSTRACT
The amount of heparin administered during peripheral angioplasty procedures is controversial and varies greatly among angiographers. Complications may result from both excessive and insufficient anticoagulation. The authors characterized the anticoagulant response to heparin in patients undergoing angioplasty by means of the activated clotting time (ACT). The ACT was measured in 64 patients who underwent lower extremity angioplasty. There was a linear relationship between heparin dose and ACT (P = .0001), but the slope of this relationship varied from patient to patient (R2 = .232). The response to heparin was blunted in one patient with thrombosis, but it was not exaggerated in patients with hematomas. Heparin anticoagulant response is highly variable, and heparin administration should be individualized according to ACT to produce a desired level of anticoagulation. Use of the ACT is a convenient and reproducible means of monitoring heparin administration and may increase safety and efficacy during peripheral angioplasty.
Subject(s)
Angioplasty, Balloon , Heparin/therapeutic use , Whole Blood Coagulation Time , Angioplasty, Balloon/adverse effects , Dose-Response Relationship, Drug , Hemorrhage/blood , Hemorrhage/etiology , Heparin/administration & dosage , Humans , Thrombosis/blood , Thrombosis/etiologyABSTRACT
Contrast media additives that bind calcium lower the total dose necessary to induce fibrillation. The method of measuring ventricular fibrillation threshold during coronary arteriography is sensitive and allows dose comparison at volumes relevant to clinical use. We compared two commercial formulations of sodium/meglumine diatrizoate for their effects upon fibrillation threshold in normal and ischemic dog hearts. Even though the formulations differed only by their additives, Hypaque 76 was significantly less fibrillatory than Renografin 76. This was observed at two different doses and in both ischemic and non-ischemic hearts. We conclude that amounts of additives capable of binding calcium should be kept as low as possible in sodium/meglumine diatrizoate formulations that are used for coronary angiography.
Subject(s)
Calcium/metabolism , Contrast Media/adverse effects , Ventricular Fibrillation/chemically induced , Angiocardiography , Animals , Coronary Disease/diagnostic imaging , Diatrizoate/pharmacology , Dogs , Dose-Response Relationship, Drug , Female , Male , Meglumine/pharmacologyABSTRACT
Contractile reserve was followed throughout the hemodynamic response to coronary arteriography by measuring the post-etrasystolic potentiation every tenth beat following the injection of 3 ml of Renografin-76 into the left coronary arteries of anesthetized dogs. During sinus beats, both systolic pressure and +dP/dt exhibited the usual biphasic response of negative inotropy for 5-8 seconds, followed by a rebound increase in contractility. However, the myocardium retained the ability to increase contractility following a precisely timed extrasystole. The pattern of hemodynamic response to ionic contrast agents is similar to the response of other interventions that decrease calcium inflow to the myocardial cell. Based upon differences in the electrophysiologic effects of ionic contrast agents, we speculate that excess sodium and meglumine transiently compete with calcium for external binding sites that supply calcium necessary for excitation-contraction coupling.
