A 58-year-old man from Delhi presents to the emergency department with acute onset chest pain and dyspnea. On examination, blood pressure is 95/60 mmHg, heart rate 110/min, and JVP is elevated at 8 cm H₂O. Auscultation reveals a loud S3 gallop and bibasal crackles. Echocardiography shows a dilated left ventricle with ejection fraction of 28%. Which phase of the cardiac cycle is primarily affected, resulting in the clinical findings observed in this patient?

Question

Accepted Answer

A. Isovolumetric relaxation with impaired ventricular filling. ## Clinical Context
This patient presents with acute decompensated heart failure (HF) with reduced ejection fraction (HFrEF). The dilated left ventricle, low ejection fraction, elevated JVP, and pulmonary edema indicate systolic dysfunction with impaired diastolic function.

## Pathophysiology of the Cardiac Cycle in HFrEF

**Key Point:** In systolic HF, the primary defect is impaired ventricular contraction during the ejection phase, but the clinical manifestations (elevated JVP, S3 gallop, pulmonary edema) are consequences of impaired diastolic function — specifically abnormal isovolumetric relaxation and ventricular filling.

### Why Isovolumetric Relaxation is Affected

In HFrEF:
1. **Delayed relaxation**: The failing ventricle has prolonged isovolumetric relaxation time due to impaired active relaxation (lusitropia) and increased chamber stiffness.
2. **Elevated end-diastolic pressure**: Because the ventricle cannot relax normally, diastolic pressures rise, causing:
   - Elevated left ventricular end-diastolic pressure (LVEDP) → transmitted backward to left atrium and pulmonary veins → pulmonary edema
   - Elevated right ventricular diastolic pressure → elevated JVP
3. **S3 gallop**: Occurs in early diastole (rapid filling phase) when the stiffened, dilated ventricle abruptly halts further filling, creating a palpable vibration.

**Clinical Pearl:** The S3 gallop in HF is a hallmark of diastolic dysfunction superimposed on systolic dysfunction. It represents the ventricle's inability to accommodate blood volume during the rapid filling phase.

### Why Other Phases Are Not Primary

| Phase | Status in HFrEF | Clinical Outcome |
|-------|-----------------|------------------|
| **Isovolumetric contraction** | Prolonged but not the primary clinical driver | Reduced stroke volume results, but elevated filling pressures are the main problem |
| **Rapid ejection** | Severely impaired (low EF = 28%) | Reduced cardiac output, but backward failure (pulmonary edema, JVP elevation) dominates the clinical picture |
| **Atrial systole** | May be lost if AF develops, but not the primary defect here | Contributes to filling but is not the main cause of the current presentation |

**High-Yield:** In HFrEF, systolic dysfunction (weak ejection) is the PRIMARY pathology, but DIASTOLIC dysfunction (impaired relaxation and filling) is the PRIMARY CLINICAL DRIVER of symptoms (dyspnea, edema, elevated JVP).

## Summary
The elevated JVP, pulmonary edema, and S3 gallop all reflect impaired isovolumetric relaxation and abnormal ventricular filling due to increased chamber stiffness and elevated diastolic pressures — not acute loss of contractility during systole.

![Cardiac Cycle diagram](https://mmcphlazjonnzmdysowq.supabase.co/storage/v1/object/public/blog-images/explanation/3209.webp)

Answer

B. Atrial systole with loss of atrial kick

Answer

C. Isovolumetric contraction with reduced stroke volume

Answer

D. Rapid ejection phase with decreased cardiac output

Explanation

Clinical Context

Pathophysiology of the Cardiac Cycle in HFrEF

Why Isovolumetric Relaxation is Affected

Why Other Phases Are Not Primary

Summary

Practice similar questions

Join our NEET PG community

Phase	Status in HFrEF	Clinical Outcome
Isovolumetric contraction	Prolonged but not the primary clinical driver	Reduced stroke volume results, but elevated filling pressures are the main problem
Rapid ejection	Severely impaired (low EF = 28%)	Reduced cardiac output, but backward failure (pulmonary edema, JVP elevation) dominates the clinical picture
Atrial systole	May be lost if AF develops, but not the primary defect here	Contributes to filling but is not the main cause of the current presentation