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Q1: Discuss the etiology and pathophysiology of hypertension.
Q2: Define arrhythmia. Discuss the etiology and pathophysiology of i) bradycardia, ii) tachycardia.

Answer 1

Q1

Etiology of hypertension

Hypertension is rise in blood pressure from its normal value. There are two types of hypertension: essential hypertension and secondary hypertension.

Etiology of secondary hypertension:

Renal: Acute glomerulonephritis, chronic renal disease, renal artery stenosis, renin producing tumors.

Endocrine: Adrenocortical hyperfunction, hypothyroidism and pregnancy induced hypertension.

Cardiovascular: Coarctation of aorta, poly arteritis, increased intravascular volume, increased cardiac output and rigidity of aorta.

Neurologic: Pshycogenic, increased intracranial pressure, sleep apnea, acute stress including surgery.

Pathophysiology of hypertension:

• The multiple mechanisms of hypertension constitute aberrations of the normal physiologic regulation of blood pressure.
• Arterial hypertension occurred when the relationship between cardiac output and total peripheral resistance altered.
• Renal hypertension, renal artery stenosis causes decreased glomerular flow and pressure in the afferent arterioles of the glomerulus.

               This induces:

• Renin secretion – initiating angiotensin II mediated vasoconstriction and increased peripheral resistance.
• Increases sodium reabsorption and hence blood volume through aldosterone mechanism.
• In pheochromocytoma, a tumor of adrenal medulla, catecholamines produced by tumor cells cause episodic vasoconstriction.

Q2. Arrhythmia: it is an abnormal cardiac rhythm, and are the most important cause of sudden death.

Etiology:

• Ischemia
• Electrolyte and pH imbalance
• Mechanical injury
• Stretching
• Neurogenic and drug influence including anthiarrhythmic agents

The causes act by either of the three mechanisms: depressed automaticity of the heart, block of conduction and reduction in the pacemaker activity and rhythms. The pathophysiology of bradycardia is dependent on the underlying cause.

Etiology of tachycardia:

• Tachycardia is caused by something that increases the normal electric impulse and increase the heart rate. Physiological causes: Exercise, fear, euphoria, anxiety.
• Pathological causes: hypotension, fever, hypovolemia, anemia, sepsis, hyperthyroidism, pulmonary embolism.
• Pharmacological causes;
• Caffiene, cocaine, nicotine, alcohol, digoxine, atropine etc.