Cardiovascular Function Alterations I

Cardiovascular Function Alterations I

• This module focuses on hypertension, dyslipidemia, and atherosclerosis.
• Learning outcomes include understanding cardiovascular physiology, pathophysiological mechanisms, clinical manifestations, diagnostic approaches, and treatment strategies for these conditions. These conditions are interconnected.
• The patient in the case study is a 52-year-old parent with persistent headaches and dizziness, who reports a blood pressure of 162/94 mmHg.
• The patient's lifestyle includes long work hours, reliance on fast food and coffee, and a BMI of 31. A family history of hypertension in their parents and siblings is noted.
• Hypertension classification: Normal <120 mm Hg and <80 mm Hg; Elevated 120-129 mm Hg and <80 mm Hg; Stage 1 130-139 mm Hg or 80-89 mm Hg; Stage 2 >140 mm Hg or >90 mm Hg.

Hypertension

• Key pathophysiological mechanisms are discussed, such as sympathetic nervous system stimulation, antidiuretic hormone (ADH) release, and the renin-angiotensin-aldosterone system (RAAS).
• The course covers the effects of sympathetic nervous system stimulation on vascular resistance, heart rate, and blood volume.
• The role of ADH is also highlighted, focusing on its effect on blood volume and pressure regulation, especially as related to fluid retention.
• Also covered in the module is the importance of the RAAS in regulating blood pressure. This involves renin release, conversion to angiotensin II, vasoconstriction, and sodium and water resorption.
• Over-expression of RAAS mechanisms can lead to chronic increases in blood pressure.
• Other mechanisms impacting hypertension include genetic factors, dietary factors, tobacco use, alcohol use, and obesity.

Pathophysiology Review

• Sympathetic nervous system stimulation, affecting α1 receptors in blood vessels (vasoconstriction) and β1 receptors in the heart (increased heart rate).
• Antidiuretic hormone (ADH) control of water reabsorption in the kidneys directly affects blood volume and pressure.
• Renin-Angiotensin-Aldosterone System (RAAS) activation and its impact on blood vessel constriction and fluid balance.

Additional Pathophysiological Mechanisms

• The effect of vasoactive mediators like endothelin (vasoconstriction), thromboxane (vasoconstriction), and nitric oxide /eNOS (vasodilation) on vascular resistance.
• The effect of vasodilators, including nitric oxide (NO) and prostaglandins.
• Problems with water retention, including excessive sodium reabsorption via the renal tubules.
• The patient's lifestyle habits are significant contributing factors to their hypertension, particularly the dietary components (coffee, fast food) and lack of exercise, that could lead to hypertension.
• The genetic predisposition to hypertension is also considered, as apparent in the parent and sibling's diagnoses.

Dyslipidemia

• The study includes a discussion of lipid types, including triglycerides and cholesterol.
• Lipoproteins, such as chylomicrons, VLDL, IDL, LDL, and HDL are explained, as well as their roles in transporting lipids. Their relationships to each other are also covered.
• The key enzyme involved in cholesterol production, HMG-CoA reductase, and its regulation are discussed.
• Mechanisms impacting the patient's diabetes diagnosis on the cholesterol levels and their metabolism are also covered.
• Genetic predisposition, dietary factors, obesity, lack of exercise, and hyperinsulinemia are mentioned as risk factors in dyslipidemia.

Atherosclerosis

• Key pathophysiological steps in atherosclerosis development, such as endothelial injury and inflammation, are detailed.
• The role of low-density lipoprotein (LDL), oxidative stress, the development of fatty streaks, and the formation of fibrous plaques are also discussed.
• The impact of hypertension, cigarette smoking, diabetes, and elevated blood lipids on the process are covered.
• Modifiable risk factors such as hypertension, tobacco use, diabetes, and obesity and non-modifiable risk factors such as genetics and family history are noted.
• The pathophysiology of endothelial injury is explained in detail, including factors that affect endothelial function and the release of vasoactive mediators. The role of the inflammatory response and the role of macrophages in atherosclerotic plaque development.
• The process of plaque buildup and its impact on blood vessels, such as narrowed lumen, are discussed.
• The implications of atherosclerosis concerning different aspects of the body systems (e.g., cardiovascular, kidney, and ocular health) are noted.