Hypertension, cardiac hypertrophy and the effects of anaesthesia

Hypertension predisposes to a heightened risk of cardiovascular events over years of follow-up of ambulatory adults and especially during the relatively brief peri-and intra-operative periods of heightened stress resulting from surgery and anaesthetic effects. Structural changes in the circulation, including left ventricular and resistance vessel hypertrophy, and systemic and coronary atherosclerosis, play an even more important role in the development of these morbid events than does the actual level of blood pressure elevation. However, chronic anti-hypertensive therapy stabilizes blood pressure and heart rate responses to stress and therapy, thereby decreasing the incidence of ischaemia, congestive heart failure, arrhythmia and cerebrovascular accident. Although optimal evidence is not yet available, it appears that continued anti-hypertensive therapy is as beneficial in the operative setting as it is chronically. Excluding diuretics and angiotensin-converting enzyme inhitors, most other anti-hypertensive medications should be continued during anaesthesia.

For intra-operative hypertension, many drugs are used, but the most evidence of cardioprotective effects has been obtained for the beta-blockers. It is important to mention that calcium-channel blockers may potentiate myocardial depression and bradycardia especially when beta-blockers are already being used.