There are 30,000 cases of sudden cardiac death each year in Spain, and many millions worldwide. 80% of cases occur in individuals over 35 with some sort of existing cardiac disease. The main cause is ischemic cardiopathology, caused by the obstruction of the coronary arteries. Obesity, hypercholesterolemia, diabetes, arterial hypertension, tobacco use and a sedentary lifestyle are the main risk factors for this lethal disease.
The perfect machine sometimes fails
The heart doesn't need any external impulse to beat. As though it were designed by the best engineers, it can generate thousands of beats a day, or some three billion over a lifetime. It does so in perfect coordination and synchronisation. The same tiny process is repeated again and again, without ever skipping a beat. Divided into four cavities, with two atria above and two ventricles below, the heart is our body’s motor.
But if its electric impulse doesn't happen correctly, arrhythmias can occur. These are the result of an alteration in the heart rate, either by a reduction or an increase in speed. When the atria stop working, the pumping action of the heart is not seriously affected, but this disorder increases the probability of generating blood clots that can cause a cerebrovascular accident if they reach the brain. This is what is commonly known as a stroke.
However, if the fibrillation takes place in the heart’s lower chambers, the ventricles, the risk is much more significant because the ventricles play a fundamental role in distributing blood and oxygen throughout the body. The left ventricle alone does 80% of the work. When the heart rate becomes chaotic, the contraction does not occur and the oxygen-rich blood cannot be pumped. If the brain goes just ten seconds without this vital oxygen, the person faints, and this is the moment when sudden cardiac death begins. Recuperating the person’s heart rate in less than ten minutes is essential to their survival, and with every minute that goes by they lose 10% of their chance for survival.
But why? They were perfectly healthy!
Sudden cardiac death often occurs in individuals who seem healthy, or often those quite, but these individuals silently carry one of the congenital conditions that can cause this affliction.
Fortunately, research into these diseases has allowed for the discovery of hundreds of genes associated with sudden cardiac death. Great strides are being made in diagnosis and prevention, thanks to the development of tools for genetic diagnosis that allow for studies in individuals and family members affected by sudden cardiac death. As you can probably imagine, any results obtained are extremely valuable for continuing our research.