18.1 Hypertension and Angina

Hypertension and angina are two crucial cardiovascular conditions that can significantly impact heart health. Understanding their mechanisms, symptoms, and diagnosis is essential for effective management and prevention of complications.

Blood pressure guidelines help identify hypertension stages, while angina symptoms signal an imbalance between heart oxygen supply and demand. Both conditions share risk factors and require a comprehensive diagnostic approach, including clinical evaluation and specialized tests to guide treatment strategies.

Pathophysiology and Diagnosis of Hypertension and Angina

Mechanisms of hypertension and angina

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• Hypertension
  • Increased cardiac output results from elevated heart rate and stroke volume, leading to higher blood pressure
  • Increased peripheral vascular resistance due to vasoconstriction, atherosclerosis (plaque buildup in arteries), and arterial stiffening contributes to hypertension
  • Imbalance between vasoconstrictors (angiotensin II, endothelin-1, catecholamines) and vasodilators (nitric oxide, prostaglandins) favors vasoconstriction and raises blood pressure
  • Genetic factors influence blood pressure regulation, with some individuals more susceptible to hypertension
  • Environmental factors such as high salt intake (sodium), obesity, and chronic stress can contribute to the development of hypertension
  • The renin-angiotensin-aldosterone system plays a crucial role in regulating blood pressure and fluid balance
• Angina
  • Myocardial ischemia occurs when there is an imbalance between myocardial oxygen supply and demand, leading to chest pain or discomfort (angina)
  • Decreased oxygen supply to the heart muscle can result from:
    1. Coronary artery stenosis: narrowing of the coronary arteries due to atherosclerosis
    2. Coronary artery spasm: sudden constriction of the coronary arteries (Prinzmetal's angina)
    3. Anemia: low red blood cell count reduces oxygen-carrying capacity
    4. Hypoxemia: low oxygen levels in the blood
  • Increased oxygen demand by the heart muscle can occur due to:
    1. Tachycardia: rapid heart rate
    2. Hypertension: high blood pressure increases the workload on the heart
    3. Hypertrophic cardiomyopathy: thickening of the heart muscle wall
    4. Aortic valve stenosis: narrowing of the aortic valve opening, increasing the workload on the left ventricle

Blood pressure guidelines for diagnosis

• Normal blood pressure: systolic < 120 mmHg and diastolic < 80 mmHg
• Elevated blood pressure: systolic 120-129 mmHg and diastolic < 80 mmHg
• Stage 1 hypertension: systolic 130-139 mmHg or diastolic 80-89 mmHg
• Stage 2 hypertension: systolic ≥ 140 mmHg or diastolic ≥ 90 mmHg
• Hypertensive crisis: systolic > 180 mmHg and/or diastolic > 120 mmHg, requiring immediate medical attention

Symptoms of hypertension and angina

• Hypertension
  • Often asymptomatic (no symptoms) in early stages
  • Possible symptoms include headache, dizziness, shortness of breath, chest pain, blurred vision, and nausea
  • Signs of hypertension include elevated blood pressure readings, retinal changes (arteriovenous nicking, hemorrhages, exudates), and left ventricular hypertrophy (S4 gallop, displaced apex beat)
• Angina
  • Symptoms include chest pain or discomfort (pressure, squeezing, fullness, or pain), often in the center of the chest and may radiate to the neck, jaw, shoulder, back, or arm
  • Other symptoms: shortness of breath, fatigue, nausea, and lightheadedness
  • Signs of angina include elevated heart rate and blood pressure during an episode, S4 gallop if left ventricular dysfunction is present, and mitral regurgitation murmur if papillary muscle dysfunction occurs

Causes and diagnosis of cardiovascular conditions

• Hypertension
  • Primary (essential) hypertension accounts for 90-95% of cases and is multifactorial, involving genetic, environmental, and behavioral factors
  • Secondary hypertension (5-10% of cases) can be caused by renal disease, endocrine disorders (primary aldosteronism, Cushing's syndrome, pheochromocytoma), obstructive sleep apnea, and coarctation of the aorta
  • Diagnostic approach involves:
    1. Confirming elevated blood pressure readings over multiple visits
    2. Assessing for end-organ damage (echocardiogram, renal function tests, fundoscopy)
    3. Evaluating for secondary causes (renal artery stenosis, aldosterone-renin ratio)
• Angina
  • Causes include obstructive coronary artery disease (a common form of ischemic heart disease), coronary artery spasm (Prinzmetal's angina), microvascular dysfunction, aortic valve stenosis, and hypertrophic cardiomyopathy
  • Diagnostic approach includes:
    1. Electrocardiogram (ECG) during an episode to detect ischemic changes
    2. Exercise stress test to assess for ischemia during physical exertion
    3. Coronary angiography to visualize the coronary arteries and detect stenosis or blockages
    4. Echocardiogram to evaluate heart structure and function
    5. Cardiac magnetic resonance imaging (MRI) for detailed assessment of heart structure and function

Cardiovascular Risk Factors and Prevention

• Major modifiable risk factors include hypertension, smoking, diabetes, dyslipidemia, obesity, and physical inactivity
• Non-modifiable risk factors include age, gender, and family history
• Prevention strategies focus on lifestyle modifications and management of underlying conditions to reduce myocardial oxygen demand and improve cardiovascular health