The heart is the most vital component of the circulatory system. Its main role is to pump blood to the whole body. Generally, the heart beats 60 to 100 times per minute, but in certain circumstances (such as during physical activity) it can reach much higher rates. The heart receives messages indicating how much blood must be pumped, increasing the cardiac rate to adapt to the person´s needs. For example, the heart beats slower during sleep, providing the necessary oxygen to the body while resting. On the other hand, during physical activity or under stress the heart pumps faster, increasing oxygen supply in response to the stimulus.
Cardiovascular diseases (CVD) affect both the heart and blood vessels, giving rise to different pathologies. Many of them are associated with unhealthy lifestyles, such as sedentarism and unbalanced diets. Therefore, adopting healthy habits can help control, prevent and/or treat the majority of these diseases.
According to the World Health Organization (WHO), CVDs cause 17.5 million deaths every year, being the primary cause of death in developed countries. However, despite the CVDs being the number 1 cause year after year, the number of deaths is generally decreasing, with the exception of those countries currently in development, where the number of deaths is rising. According to the Spanish National Statistics Institute (NSI) in 2007, Spain presented one of the lowest mortality rates by CVDs, despite being the major cause of death (32.2%). Cancer, on the other hand, was in second place, with 26.8% of cases, while the third case being respiratory system-related diseases (11.4% of deaths). There are different types of CVDs, which can be grouped into two categories:
- Congenital: anomalies of the heart present since birth.
- Acquired: are the most prevalent, and are related to the lifestyle.
The coronaries are vessels that provide blood to the cardiac muscle. It is the most common cardiac disease in adults and elderly, and begins with an irritation or lesion in the cellular layer of the interior of the arterial wall: the endothelium. This damage is caused by the accumulation of macrophages in the intimate layer of the artery (between the endothelium and smooth muscle). These macrophages derive from monocytes circulating in the blood that present high levels of fat and cholesterol, clinging themselves to this layer and provoking its thickening, reducing blood flow. The thickened area (called atheromatous plaque) fills with soft substances, composed of various fat materials (mainly cholesterol), smooth muscle cells and connective tissue cells. Atheromas can form in any large or medium artery, but are generally found where they branch (possibly due to the constant turbulence that these areas present, which is susceptible to arterial wall damage and therefore atheroma formation). If the plaque is formed in the coronaries, blood administration to the heart is altered.
Coronary disease can appear in different forms. Sometimes it appears abruptly, while in other cases it advances slowly, following a foreseeable course. A very dangerous form is silent ischemia. This disease is due to the appearance of an artery obstruction but does not present symptoms, resulting in a fatal heart attack with no initial pain. The atheromatous plaque, or part of it, can latch off and produce a thrombosis that can block small vessels of the brain, resulting in a stroke. If the blockage occurs near the heart, this can provoke a heart attack, accompanied by an ischemia cardiopathy (lack of oxygen), resulting in necrosis (tissue death) of a part of the heart. Unless blood flow can be restored in a few minutes, the muscle damage increases and the ability for the heart to recover is hampered.
This includes the pathologies related to high levels of lipids (mainly triglycerides) or cholesterol in blood. Cholesterol is a fat substance that is found in all cells of the body and is produced in the liver, is involved in the formation of cellular membranes as well as the production of hormones and bile salts. Also, cholesterol can be obtained from animal products (meat, eggs, seafood, fish and dairy products). Excess cholesterol and triglycerides in the blood, one of the major risk factors in heart disease as commented previously, correlates with the formation of atheromatous plaques and cerebral-cardiovascular damage. Cholesterol and triglycerides travel through the bloodstream as lipoproteins. The most important lipoproteins are low density and high density lipoproteins (LDL and HDL, respectively). High levels of LDL increases the risk for cardiovascular disease, while high HDL levels indicate a lower risk.
Hypertension (high blood pressure)
The hearts acts as a pump that sends 5L of blood to the body per minute. When the hearts contracts, it impulses blood into the arteries. The highest pressure reached is called systolic or maximum. When the heart relaxes, the lowest pressure reached is called diastolic or minimum. A normal blood pressure in adults is under 120/80 mmHg or “12/8.”
Arterial hypertension is a disease caused by arterial wall rigidness (such as in the formation of an atheramotous plaque) or by excess liquid in circulation (such as in hydrosaline retention). When blood pressure is much higher than normal, this can damage the heart and arteries in the long term, as well as other organs of the body. A person with arterial hypertension presents values at or above 140/90 mmHg or “14/9.” It is important to note that to diagnose hypertension it is necessary to measure the blood pressure several times at different time points, and that the values are persistently high; a single measurement is not sufficient for diagnosis.
This disease is defined as the combined clinical manifestations that predispose an individual to a high risk for severe cardiovascular disease. There is no single criteria for diagnosis. For the American Heart Association, metabolic syndrome is diagnosed when the individual presents at least three of the following symptoms:
In conclusion, a healthy lifestyle is the most recommendable method to prevent these diseases. Avoiding excess weight, reduce stress and anxiety, daily light exercise and maintain a healthy diet (preferably low on simple sugars, sodium and saturated fats) is fundamental to maintain the correct functioning of the cardiovascular system and therefore increase both life quality and expectancy.