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A low osmolality contrast medium (Iopamidol) caused less cardiac disturbance on isolated rabbit heart than a high osmolality medium (Urografin). The same effects were induced by glucose solutions iso-osmolal with the two media. After perfusion with Propranolol (1 microgram/ml) and Cimetidine (1 microgram/ml) the observed effect was unaltered.

The isolated rat heart model was used to examine the effect of a new nonionic contrast agent, B-15,000 (Iopamidol), on cardiac function. Comparative studies were performed with Amipaque, Renografin 60, Renografin 76, and Vascoray. The three ionic contrast agents had significantly greater detrimental effects on cardiac function than either nonionic agent. The results support the continued evaluation of the nonionic agents for use in coronary angiography.

The effect of two low osmolar contrast media (sodium ioxitalamate and sodium ioxaglate) and two nonionic media (iohexol and iopamidol) on cellular electrophysiological properties of sheep myocardium and Purkinje fibres was studied at two concentrations of each medium. Neither sodium ioxitalamate nor ioxaglate had significant effects on any of the parameters measured. Iohexol (10 mL/L) caused a loss of resting potential, a decrease in action potential and duration, and a decrease in refractory period of the myocardium. No change in Purkinje fibres was observed. Iopamidol induced an increase in relative refractory period in both myocardium and Purkinje fibres at 1 mL/L and had a significant effect on all parameters studied at 10 mL/L. Automaticity was not observed after perfusion with any agent at either concentration.

Selective injection of contrast media into the canine common carotid artery results in alterations in carotid flow, heart rate, and systemic arterial pressure. In this study the responses to injections of the nonionic agents metrizamide and iopamidol were compared to the responses to the ionic agents meglumine iothalamate, meglumine sodium diatrizoate, mannitol, and saline solution. Heart rate and pressure responses were smallest for metrizamide, greater for iopamidol, and greater still for the hypertonic ionic agents: responses were roughly correlated to agent osmolality. Carotid flow increased with all agents and was roughly proportional to the agent's osmolality. The exception was metrizamide which despite its lowest osmolality, produced a large increase in flow which was maintained much longer than for other agents. The total response to the nonionic agents was judged less severe than to the ionic agents; however, the responses to all agents were transient and not life threatening.

The influence of contrast medium on systolic and diastolic left ventricular function was studied in eight patients with coronary heart disease and in five dogs during and five minutes after ventriculography. Two biplane ventriculograms were performed in 5-minute intervals, in the dogs an additional one after 10 minutes. 0.66 cc/kg BW of sodium methyl-glucamin-iothalamate were injected during diastole into the left ventricel. 1. During ventriculography there are only slight changes of left ventricular volumes, pressures and diastolic compliance. The first four opacified heart cycles can be evaluated for the analysis of left ventricular function. 2. In patients with coronary heart disease there are much more pronounced alterations of systolic ventricular function 5 minutes after Ventriculography than in the normal dog. The ischemic ventricle has a reduced tolerance for volume load and negative inotropic effect of contrast media. In patients and dogs diastolic compliance is significantly increased 5 minutes after the injection of contrast medium. After 10 minutes however in the dogs compliance is significantly decreased. Analysing left ventricular function by repeated ventriculographies one has to take into account that the function is altered by the first angiogram. The degree of the changes depends on the initial hemodynamic conditions and on the time interval between the ventriculograms.