Cardiovascular diseases (CVDs) are the leading causes of death in the world. All CVDs involve physiological complications in the circulatory system. Genetics, poor dietary choices and lifestyle can affect the physical properties of the circulatory system so that it can no longer function with optimal efficiency, causing CVDs.
Various factors of one’s lifestyle can affect susceptibility to CVDs. These factors include: smoking tobacco products, consumption of alcohol, inadequate level of physical activity, and an unhealthy diet. A study conducted in China revealed that only 10% of the adult population demonstrates healthy lifestyle habits in all four of these categories. However, adults were more likely to make positive lifestyle changes after being diagnosed with a CVD (Wang et al., 2017).
China produces and consumes more tobacco products than any other country, yet 50% of the smoking Chinese population is unaware of the correlation between tobacco use and onset of CVDs (Wang et al., 2017). Smoking tobacco products can cause ventricular arrhythmia. Also known as ventricular tachycardia, ventricular arrhythmia is characterized by rapid, abnormal contractions of the lower heart chambers. When the heart beats rapidly in this manner, it can prevent circulation of oxygen-rich blood to the brain and the rest of the body, resulting in sudden cardiac death. These abnormal contractions can be attributed to the effect of nicotine on the serum catecholamine concentration (Goldenberg et al., 2003).
Light and moderate alcohol consumption is associated with a reduced risk of CVDs, in comparison to those who abstain from drinking. The consumption of alcohol causes an increase in high-density lipoprotein cholesterol (HDL-C). HDL-C carries cholesterol from the tissues to the liver to be excreted in bile. Drinking in excess, however, is not clearly associated with a higher or lower incidence of CVDs (Mukamal, Chen, Rao, ; Breslow, 2010).
Atherosclerosis and hypertension are the predominate causes of cardiovascular disease; both of these can directly stem from poor nutrition (Widmer, Flammer, Lerman, ; Lerman, 2015). Dysfunction in glucose metabolism and hypertension are examples of genetic forces that cannot be prevented; whereas smoking and ingesting high levels of low-density lipoprotein cholesterol (LDL-C) are preventable with adequate nutrition and improvement of lifestyle choices.
The circulatory system is comprised of arteries, arterioles, capillaries, venules, and veins of varying size, structure, and function. These structures are pathways through which blood circulates throughout the body driven by the heart’s pumping action. Blood follows a specific flow of circulation; when blood leaves the heart via the aorta, it is directed into various branching arteries that lead to the body’s organs. Once the blood reaches the organs, it is distributed to over ten billion capillaries through small versions of arteries called arterioles. During the time where the blood is in the capillaries it diffuses nutrients and oxygen to tissue cells through the exchange of interstitial fluid across the capillary walls. As well as giving off vital nutrients and oxygen, the capillaries serve as a waste removal system. From the capillaries, blood flows through venules, small passages that lead to veins. Veins have thin, pliable walls because they do not need to withstand the high pressures as the other vessels in the system; they increase in size until reaching the venae cavae where blood is recirculated via pumps from the heart. Like any other systematic machine that is kept in good repair the cardiovascular system is mechanically sound, and will function properly until interrupted or total exhaustion – death. All blood vessels are lined with a single layer of cells called the vascular endothelium. Dysfunction of the vascular endothelium plays a significant role in the initiation and development of CVDs (Matsuzawa, Kwon, Lennon, Lerman, ; Lerman, 2015).
The various structures of the cardiovascular system individually have different physical and chemical characteristics that allow for proper functioning. Vascular homeostasis is regulated by the vascular endothelium. Vasoconstriction, leukocyte adhesion, platelet activation, oxidative stress, thrombosis, coagulation, and inflammation are all functions of the vascular endothelium; however, dysfunction of these processes can lead to CVDs (Favero, Paganelli, Buffoli, Rodella, ; Rezzani, 2014). Vasoconstriction and vasodilation describe diameter changes of the blood vessels that alter blood pressure; vasoconstriction causes the blood vessels to narrow and increase blood pressure. High blood pressure is also commonly called hypertension. Leukocyte adhesion and platelet activation are functions of the vascular endothelium’s inflammatory response. Atherosclerosis, hypertension, diabetes, and cardiac valvular degeneration are CVDs associated with dysfunctions of the vascular endothelium (Favero et al., 2014).
Nutrition / Cholesterol
The body utilizes two different cholesterols, HDL-C is synthesized by the body and exerted from the liver into the stomach bile, whereas LDL-C is absorbed through diet. The ratio of HLD-C to LDL-C is important in the determination of cardiovascular health. Hypercholesterolemia, an excessive amount of cholesterol in the blood, is a direct risk factor for the onset cardiovascular disease. The presence of lipoproteins such as polipoprotein along with small dense LDL-C particles and low HDL-C omnisciently predict cardiovascular disease in people with visceral adiposity (Widmer et al., 2015).
The intestinal epithelium tissue regulates the absorption of dietary fats: mono-unsaturated fats, poly-unsaturated fats, and saturated fats. The regular consumption of mono and poly-unsaturated fats will lower cholesterol levels in the blood as well as reduce the risk of cardiovascular disease. The Mediterranean Diet is rich with mono-unsaturated fats from olive oil, fruits, vegetables, whole grains, nuts, and legumes (Widmer et al., 2015). Linoleic acid, which is found in omega-6 poly-unsaturated fatty acids, has the ability to physiologically lower blood cholesterol levels. Furthermore, omega-3-polyunsaturated fatty acids, commonly found in fish, are considered cardio protective. Cardio protective fatty acids work to protect against cardiovascular disease rather than just providing preventative maintenance. The Mediterranean Diet could be effective to fight cardiovascular disease as an alternative to the common pharmaceuticals: aspirin, beta-blockers, ACE-inhibitors (Widmer et al., 2015).
Another technique commonly used by registered dieticians to combat hypertension is the Dietary Approaches to Stop Hypertension (DASH) diet. To decrease the risk of hypertension, it is necessary to reduce the dietary intake of sodium while increasing the dietary intake of potassium in efforts to enhance a person’s sensitivity to salt. This diet utilizes low sodium and high potassium foods to create a balanced diet that will effectively relieve hypertension and thus reduce the risk for cardiovascular disease. To avoid redundancy, the consumption of fatty acids should be limited with poly-unsaturated fats coming from plants, seeds, nuts, and fish being the only fatty acid consumed. These fatty acids will effectively lower LDL-C levels and raise HDL-C levels along with protecting the cardiovascular system from disease (Chiu et al., 2016).
Unsaturated fatty acids are molecularly configured with a cis orientation – simply meaning that they have hydrogen atoms on the same side of the chain resulting in a “kinky” fatty acid. Industrialization has brought hydrogenation to fatty acids. When unsaturated fatty acids are exposed to hydrogenation, they are molecularly rearranged into the trans configuration – meaning that the hydrogen atoms are rearranged to be on opposite sides of the chain. Hydrogenated fatty acids are physiologically indigestible; this drastically affects the HDL-C to LDL-C ratios and subsequently causes cardiovascular disease (Liu et al., 2017).
The consumption of saturated fatty acids increases blood LDL-C levels and can lead to the onset of type-2 diabetes. Increased levels of LDL-C in the blood will result in the oxidation of the cholesterol, which leads to atherosclerosis. While there are many socioeconomic factors that affect one’s nutritional habits, dietary adequacy is an important consideration to treat and prevent the obesity epidemic that contributes to 40% of premature deaths associated with cardiovascular disease (Widmer et al., 2015).
Atherosclerosis, or atherosclerotic plaque formation, occurs when plaque – made up of LDL-C – layers the walls of the arteries resulting in narrowed passageways. Narrowing of the arterial passageways causes strain on the heart to palpate blood through the body, causing hypertension. The body’s inflammatory response in the pathogenesis of atherosclerosis also contributes to hypertension. The purpose of the inflammatory response is to repair and protect; however, it is possible for inflammation to cause harm in its efforts to rid the body of sickness or foreign objects. When LDL-C travels through the arteries it causes abrasions in the arterial walls. These abrasions, which turn into lesions, activate the arterial inflammatory response. T-cells, called leukocytes, enter lesions in the arterial walls; due to the inflammatory characteristics of the leukocytes, the arterial walls become inflamed resulting in hypertension (Favero et al., 2014). Other factors contributing to the development of atherosclerosis include: free radicals, infectious microorganisms, stress, hereditary hypertension, and toxins from cigarettes.
CVDs and Diabetes
Cardiovascular diseases are responsible for approximately two-thirds of deaths in people with diabetes mellitus, especially type-2 diabetes (Low Wang, Hess, Hiatt, ; Goldfine, 2016). Uncontrolled diabetes causes excessive levels of glucose in the blood, promoting oxidative stress, which results in inflammation and hypertension. Obesity induces the generation of dyslipidemia in the arteries and heightens one’s risk for diabetes. Dyslipidemia is characterized by abnormal amounts of lipids in the blood; adipose tissue causes high levels of free fatty acids to make their way to the liver, subsequently initiating the synthesis of triglyceride-rich lipoprotein. High levels of this triglyceride-rich lipoprotein, also known as very low-density protein (VLDL), and intermediate-density protein have the same effects as LDL-C in the oxidized lipoprotein inflammatory response. Elevated levels of VLDL cause the levels of the good cholesterol, HDL-C, to decrease subsequently causing arterial inflammation and CVDs. Cardiovascular diseases most common in patients with diabetes mellitus include: coronary heart disease, ischemic stroke, peripheral artery disease, and heart failure (Low Wang et al., 2016).
In the event that dietary actions alone are not enough to aid with the prevention or reversing of cardiovascular disease, pharmaceutical mediation is required. Aspirin aids in reversal of inflammation thus interrupting the pathogenesis of atherotherombosis. Physiologically, acetylsalicylic acid or Aspirin effectively inhibits the accumulation of blood platelets that are affected by LDL-C. Clients at risk of chronic cardiovascular disorders are prescribed with a low-dose aspirin regimen. Lipid-lowering strategies can also aid in the prevention of cardiovascular disease in patients with hypercholesterolemia; however obesity significantly limits progression of these strategies. To combat the counterproductive effects of obesity, aggressive lipid reduction through the use of statins will effectively reduce coronary plaque development in obese patients. Phytosterols are prescribed to patients in extreme cases; these sterols interact with the membrane of the body’s intestine to block cholesterol absorption (Ittaman, VanWormer, ; Rezkalla, 2014).
When pharmaceutical interventions are not enough, surgical techniques might be used to alleviate or even reverse the cardiovascular disease. In the case of atherosclerosis, stents are used to line the inside of coronary arteries, effectively preventing the further narrowing of the affected passageway. The use of stents cannot reverse cardiovascular disease; they only reduce patient’s symptoms of angina (chest pains) and reduce the risk of a heart attack. Stents are minimally invasive; more extreme cases require a more invasive coronary bypass. A coronary bypass utilizes healthy arteries from elsewhere in the body to create new pathways for additional blood supply to the heart. While these surgical procedures prove to be effective, complications may still arise and are often unpreventable (De Luca et al., 2016).
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