Diastole

Definition

Diastole is the phase of the cardiac cycle during which the ventricles relax and fill with blood from the atria. Coronary artery perfusion occurs predominantly during diastole.

Clinical Significance

• The diastolic blood pressure is the 'bottom number' (normal less than 80 mmHg).
• Tachycardia shortens diastole, reducing ventricular filling and coronary perfusion.
• Diastolic dysfunction (impaired relaxation) causes HFpEF (heart failure with preserved ejection fraction).

Related Concepts

Stroke volume depends on diastolic filling (preload). Conditions that stiffen the ventricles (hypertension, hypertrophy, constrictive pericarditis) impair diastolic filling.

Nursing Considerations

Monitor diastolic BP: elevated diastolic may indicate persistent hypertension and end-organ risk, such as in hypertensive crisis, target gradual reduction, for tachyarrhythmias, rate control improves diastolic filling and cardiac output.

NCLEX Relevance

Know diastole vs systole. Understand why heart failure with preserved EF is still significant disease.