What is the pathophysiology and management of diastolic hypertension?

Pathophysiology of Diastolic Hypertension

Diastolic hypertension is primarily caused by increased peripheral vascular resistance resulting from functional and structural changes in small arteries and arterioles, which leads to elevated cardiovascular morbidity and mortality. 1

Pathophysiological Mechanisms

Diastolic hypertension involves complex interactions between multiple systems:

Microcirculation Changes

• Endothelial dysfunction: Impaired nitric oxide production and increased endothelin-1 release lead to vasoconstriction
• Increased vasoreactivity: Heightened response to vasoconstrictors
• Vascular remodeling: Thickening of arteriolar walls and narrowing of lumen
• Fibrosis and inflammation: Progressive structural changes in vessel walls
• Elevated peripheral vascular resistance: The primary hemodynamic abnormality 1

Systemic Factors

• Renin-angiotensin-aldosterone system (RAAS) activation: Promotes sodium retention, vasoconstriction, and vascular remodeling
• Sympathetic nervous system overactivity: Increases heart rate, cardiac output, and vasoconstriction
• Renal sodium handling abnormalities: Leads to volume expansion and increased cardiac output
• Genetic factors: Multiple genes influence blood pressure regulation 1

Age-Related Considerations

• Diastolic blood pressure typically increases until age 50-60, then gradually decreases
• In younger individuals, diastolic hypertension is the predominant form and drives coronary risk 2
• In contrast, systolic hypertension becomes more prevalent with aging due to arterial stiffening 3

Clinical Significance and Complications

Persistently elevated diastolic blood pressure leads to hypertension-mediated organ damage (HMOD) affecting:

1. Heart: Left ventricular hypertrophy, diastolic dysfunction, heart failure
2. Brain: Stroke, cognitive impairment, dementia
3. Kidneys: Albuminuria, reduced GFR, chronic kidney disease
4. Eyes: Retinopathy
5. Blood vessels: Accelerated atherosclerosis, arterial stiffening 1

Severe Manifestations

In severe cases, diastolic hypertension can progress to malignant hypertension, characterized by:

• Diastolic BP usually >140 mmHg
• Vascular damage with retinal hemorrhages, exudates, or papilledema
• Myointimal proliferation and fibrinoid necrosis of vessel walls
• Risk of hypertensive encephalopathy and acute kidney injury 1

Management Approach

Blood Pressure Targets

• For most patients: <130/80 mmHg
• For elderly patients: Maintain diastolic BP ≥70 mmHg to prevent tissue hypoperfusion 4
• For patients with coronary artery disease: Maintain diastolic BP ≥70 mmHg to ensure adequate coronary perfusion 4

Pharmacological Treatment

1. First-line agents:

   • ACE inhibitors (e.g., lisinopril) 5
   • Angiotensin receptor blockers (e.g., losartan) 6
   • Calcium channel blockers (e.g., amlodipine) 7
   • Thiazide diuretics

2. For resistant hypertension:

   • Add mineralocorticoid receptor antagonists (e.g., spironolactone)
   • Consider loop diuretics in patients with chronic kidney disease 4

Lifestyle Modifications

• Weight loss if overweight/obese
• DASH-style eating pattern
• Sodium reduction (<2,300 mg/day)
• Increased physical activity
• Moderation of alcohol intake 4

Important Clinical Considerations

• J-curve phenomenon: Excessive lowering of diastolic BP (<60-70 mmHg) may increase risk of coronary events in patients with established coronary artery disease 4, 8
• Treatment thresholds:
  • DBP 80-89 mmHg: Consider medications if cardiovascular risk is high
  • DBP ≥90 mmHg: Initiate pharmacologic therapy
  • DBP ≥100 mmHg: Prompt initiation of two drugs or a single-pill combination 4
• Monitoring: Check for symptoms of hypoperfusion (dizziness, fatigue, syncope) in patients with treated hypertension 4

Special Populations

• Elderly patients: More susceptible to low diastolic BP due to arterial stiffening; monitor closely for adverse effects 4
• Patients with coronary artery disease: Particularly vulnerable to myocardial ischemia with low diastolic BP 4
• Diabetic patients: Target BP <130/80 mmHg; consider ACE inhibitors or ARBs as first-line therapy 4

Remember that while controlling diastolic hypertension is crucial for reducing cardiovascular risk, overly aggressive treatment that excessively lowers diastolic pressure should be avoided, especially in patients with coronary artery disease or the elderly.