- Accounts for
over 450,000 deaths per year in the U.S.
- Occurs without
warning, often in the prime of life.
- Causes sudden
death - half its victims die before receiving medical treatment.
artificial kidney machines to live.
PROGRESS
IN MEDICAL RESEARCH
Coronary artery
disease is the leading cause of death, despite a decline in
mortality. Over one million Americans per year experience
a myocardial infarction, a "heart attack"; 450,000 will die
due to ventricular fibrillation. This refers to a change in
electrical activity resulting in chaotic functioning of cells
which once worked in unison to provide the "pumping" action
of the heart. If treated within minutes by an application
of a strong electrical shock through the chest and heart muscle,
the heart rhythm can be restored to normal and life maintained.
People who survive
may still be subject to a fatal outcome if enough heart muscle
is damaged by the attack. This results from insufficient blood
and oxygen reaching a portion of the heart due, in most instances,
to a blood clot developing in the arterial system. The damaged
muscle dies and is unable to function as a mechanical pump.
This decreases blood flow to other vital organs and leads
to death. With less damage, chronic congestive heart failure
may ensue.
How
has animal research helped?
Animal research
has contributed to understanding the electro-physiology of
the normal heart and the changes which occur during a heart
attack. Knowledge about abnormal electrocardiographic (EKG)
patterns associated with heart attack, as well as using an
EKG to diagnose myocardial infarction, was derived from experiments
on the dog heart. The result of animal studies in the dog
lead to the development of the electrical defibrillator. The
implantable pacemaker and defibrillator have given countless
patients hope for survival. These advances, which today are
common, would not have been possible without the ability to
evaluate their potential in the living animal. Recently there
has been dramatic improvement in the management of patients
experiencing myocardial infarction due to a blood clot formed
in a major vessel supplying the heart. In such cases, blood
flow must be restored rapidly if heart muscle is to survive.
Studies in animals show that clots may be "dissolved" quickly
and safely. Drugs first demonstrated effective in animals
are now used to treat patients who have a heart attack. What
once required a long hospital stay has now been reduced to
a few days. Dogs and rabbits have been the major contributors
to improving survival for patients with coronary artery disease.
The drug Propranolol was a laboratory curiosity until studies
in the dog showed it could prevent ventricular fibrillation.
It was the first of several drugs found to reduce sudden coronary
death in patients recovering from a heart attack.
What
lies ahead?
More remains to
be accomplished, especially in the area of congestive heart
failure. Digitalis remains the only drug found to benefit
patients with failing hearts, despite the fact that its use
is associated with risk of toxic side effects. Today newer
drugs are showing promise, however, because of the complex
biology of the heart, animal studies in which effects of a
drug can be studied and compared to known treatments are still
vital. The advances in cardiovascular medicine are the direct
result of investigators using animal research as a source
of information to develop effective lifesaving treatments.
Still, the challenge continues as heart disease remains the
number one cause of death in the U.S. Animal research is crucial
to the future success of treating patients with coronary artery
disease.related disorders.
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