Heart sympathomimetics affecting

Although ketamine produces direct myocardial depression, it has significant indirect cardiovascular effects through sympathomimetic effects and stimulation of the vasomotor centre. The heart rate and systolic blood pressure increase by 30% and occasionally up to 100%. Owing to the increased cardiac work and myocardial consumption, ketamine adversely affects the balance between myocardial oxygen supply and demand. Consequently, it is not recommended for use as the sole agent in adults with severe cardiovascular disease. However, the same haemodynamic effects, particularly the raised systemic vascular resistance, make the agent particularly suitable for children with cyanotic heart disease. 

It became apparent early in the century that some anamolous and some seemingly paradoxical results could be obtained by experimenting with sympathomimetic agents and their antagonists. For example, IV EP causes an increase in systemic blood pressure, increased tone in arterioles, a faster heart rate, and greater force of cardiac contractions. If laboratory animals are pretreated with ergot extracts, blood pressure falls without, however, affecting... 

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