112. Chronic hypotension - classification, etiology, pathogenesis, clinical manifestations.

Chronic hypotension - classification, etiology, pathogenesis, and clinical manifestations.

Chronic hypotension is persistent abnormally low systemic arterial blood pressure, typically systolic BP <90 mmHg and/or diastolic BP <60 mmHg, maintained over a long period, and not secondary to acute causes.

Classification

1. 1 Primary (constitutional) hypotension

• "Physiologic" or "constitutional" hypotension.
• Common in young, slim individuals, especially women.
• Often familial.

1. 2 Secondary hypotension

Caused by underlying diseases or systemic disorders:

Endocrine causes

• Addison’s disease (chronic adrenal insufficiency).
• Hypothyroidism ( myxedema ).
• Hypopituitarism.

Cardiovascular causes

• Chronic heart failure with low cardiac output.
• Advanced valvular heart disease.

Neurogenic causes

• Autonomic failure (diabetic autonomic neuropathy, multiple system atrophy).
• Chronic spinal cord injuries.

Iatrogenic/ drug- induced

• Overuse of antihypertensive medications.
• Chronic vasodilator therapy.
• Chronic diuretic use leading to volume depletion.

Pathogenesis

Primary hypotension

• Possibly genetic predisposition.
• Enhanced vagal tone and lower sympathetic activity → lower baseline vascular tone and heart rate.

Secondary hypotension

1. 1 Reduced cardiac output

Heart unable to maintain adequate pressure (heart failure, severe bradyarrhythmias ).

1. 2 Decreased vascular tone

• Autonomic nervous system failure → impaired vasoconstriction.
• Endocrine deficiencies (e.g., cortisol deficiency → reduced vascular reactivity).

1. 3 Reduced blood volume

Chronic hypovolemia due to renal salt- wasting, diuretics, or endocrine issues.

Compensatory mechanisms

• Activation of sympathetic nervous system → tachycardia, peripheral vasoconstriction.
• RAAS activation → sodium and water retention to increase volume.
• ADH release → water retention.

In chronic hypotension, these mechanisms are often inadequate or blunted.

Clinical manifestations

General symptoms

• Weakness, fatigue.
• Dizziness, especially on standing (orthostatic intolerance).
• Blurred vision.
• Cold extremities.
• Increased susceptibility to fainting (syncope).

Constitutional hypotension

• Usually asymptomatic or mild symptoms.
• Often well- tolerated.

Secondary hypotension

• More pronounced symptoms due to underlying disease.
• Possible weight loss, skin hyperpigmentation (Addison’s disease).
• Bradycardia or arrhythmias (heart failure- related).
• Peripheral edema (heart failure).