We focus on
understanding the origin and evolution of arrhythmias by combining clinical,
experimental, and theoretical work, with a special emphasis in computer
simulations.
Heart disease is one of the most prevalent diseases in the
world and is the leading cause of death in industrialized countries. In the US
alone, cardiovascular disease affects about 68 million people (roughly 25% of
the total population) from both sexes and all races and ages and costs an
estimated $117 billion annually [1]. Nearly 1/3 of the 2.3 million US deaths
reported annually are due to heart disease, as many as from cancer, accidents,
pneumonia and diabetes altogether [1]. About 30% of these deaths occur suddenly
and unpredictably as a result of fast-developing electromechanical malfunctions
of the heart [2]. These arrhythmias lead to an inadequate blood supply
for the body by disrupting the normal cardiac cycle and compromising the
heart's pumping action.
Statistics from the National
Center for Health Statistics [1] and from the American Heart Association
[2].
(a) A single electrical wave produced by the
heart's natural pacemaker spreads throughout the heart and induces a
contraction. These waves normally occur about once every 0.8s.
(b) A spiral wave of electrical activity generated in the heart with a period
of about 0.2s can produce the fast oscillations characteristic of an arrhythmia
called tachycardia, which often directly precedes the onset of fibrillation.
(c) Multiple spiral waves produced by the breakup of a spiral wave can lead to
the fast irregular oscillations characteristic of fibrillation. (Experimental
movies courtesy of Richard Gray)
It has become widely accepted that the most dangerous cardiac arrhythmias are
due to reentrant waves, such as the spiral waves illustrated in (c) of the
above figure. These electrical waves circulate repeatedly through the tissue
with higher frequency than the heart's pacemaker, thereby altering the heart's
regular function and resulting in inadequate pumping. We and researchers
at other institutions are continuing to investigate how arrhythmias develop
and how they depend on the dynamics of individual cells and cardiac tissue
structure in order to develop better methods for treating and preventing
arrhythmias.