The control of heart rate: the physiology of the sinoatrial node and the role of the If current |
A heart will beat approximately 25108 times during
the course of a human being's life. The observation
that most mammals share the same number of heart
beats per lifetime, be it a mouse (600 bpm for 2 years)
or a giant tortoise (6 bpm for 200 years), has led
people to suggest that if we slowed our heart rate we
might live longer! While there may not be a causal
relationship in fit healthy animals, there is an impressive
literature accumulating suggesting that there
is a clear and strong association between a lower heart
rate and improved prognosis in a variety of diseases.
It is, of course, in cardiovascular disease where the
slowing of heart rate with specific bradycardic agents
may offer the most advantage. The question as to
whether If inhibition can specifically improve morbidity
and life expectancy in cardiovascular disease is
one we only recently have had the tools to answer, and
the introduction of ivabradine into the armamentarium
offers a unique opportunity to address this question.
We will know a lot more when the BEAUTIFUL
trial (MorBidity-mortality EvAlUaTion of the If inhibitor
ivabradine in patients with coronary disease
and left ventricULar dysfunction) concludes in December
2007...
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