The heart is a muscular organ that is about the size of a
closed fist that function as the body’s circulatory pump. The heart is divided
into four chambers. The two upper chambers are called the atria. The bottom two
chambers are the ventricles. The interventricular septum separates the left
ventricle from the right ventricle. The
blood return from the entire body deoxygenated and then enters the heart
through the right atrium. It then passes to the right ventricle where it is
pumped through the pulmonary artery to the lungs to become loaded with
oxygen. Oxygenated blood returns to the
left atrium and then passes down into the left ventricle where it is pumped
back into the circulation through the aorta. Many conditions may lead to sudden
cardiac death including hypertrophic cardiomyopathy (HCM), commotio cordis,
coronary artery disease (CAD), and myocarditis. Hypertrophic cardiomyopathy is
a disease of the heart muscle that leads to abnormal thickening. HCM is the most common cause of cardiac
sudden deaths in athletes. It is the most common genetic heart malformation in
athletes affecting 1/500 individuals.
This abnormal thickening of the heart muscle occurs due to an autosomal
dominant genetic abnormality of the muscle cell proteins. Asymmetrical thickening
of the interventricular septum may lead to a condition known as Hypertrophic
Obstructive Cardiomyopathy or HOCM. It may lead to intermittent cardiac outflow
obstruction with may ultimately cause sudden cardiac death. Abnormal systolic anterior motion (SAM) of
the mitral valve leaflet exacerbated by exercise may lead to aortic obstruction
and sudden death. Increased heart rate during exercise leads to decreased
filling of the left ventricle with blood. This leads to a narrower left
ventricular chamber that may increase the chances of aortic obstruction. Therefore, HCM is an absolute
contraindication to vigorous exercises.
Most of the time, patient are asymptomatic and the condition is found
incidentally during regular physical examinations. Thorough history taking is one
of the most important parts of the examination. Some patients may present with
one or more of the following symptoms: dyspnea on exertion, angina/chest pain,
palpations, syncope, positive family history, and sudden cardiac death. Cardiac auscultation may reveal an ejection
systolic murmur that is best heard at the left parasternal edge and it
increases in intensity with maneuvers such as decreased left ventricular venous
return when standing abruptly, or performing the Valsalva maneuver. The ECHO is
the best study of choice. The majority of patients have normal life
expectancy. However, risk assessment for
the development of sudden cardiac death should be performed. Patients with a
high risk of developing sudden cardiac death may benefit from the implantation
o f a defibrillator. Vigorous exercise should be avoided in patients with HCM.
Genetic testing and physical screening for the family members. Symptomatic
patients are treated medically first in order to control their symptoms. Surgical
intervention including septal ablation and surgical myomectomy are indicated
only after failure of all drug therapies to control the patient’s
symptoms. Sudden death of a healthy
individual with no underlying cardiac disease due to ventricular fibrillation
following g a blunt, nonpenetrating blow to the precordial area of the chest.
Sports with a higher risk of commotion cordis include baseball, hockey,
lacrosse, cricket, rugby , boxing, karate, and other martial arts. The chances
of developing commotio cordis are influenced by factors such as the injury
being from a high energy impact, and the site of impact (anterior chest wall
over the heart). This also translates as
the timing of impact relative to the cardiac cycle. The risk of commotio cordis
increases when the impact coincides with the first 10-30 milliseconds of the
ascending phase of the T wave. Defibrillation should be started as soon as
possible, preferably within the first three minutes. Players should be advised
to wear proper protective gear and to avoid blocking balls or pucks with thir
chest. Furthermore, the presence of automated external defibrillators at
sporting events and training grounds have been shown to decrease mortality
rates with commotio cordis.
