Guide to Gallop Rhythms
Gallop Rhythms: S3 & S4
This guide clarifies the clinical significance of extra heart sounds. Understanding these gallops is a key step for students in advanced cardiac assessment.
S3 vs. S4: Key Distinctions
Differentiating between S3 and S4 is critical. Their timing, mechanism, and associated conditions are distinct.
| Feature | Third Heart Sound (S3) | Fourth Heart Sound (S4) |
|---|---|---|
| Timing | Early Diastole (after S2) | Late Diastole (before S1) |
| Cadence | “Ken-tuck-y” (S1-S2-**S3**) | “Ten-nes-see” (**S4**-S1-S2) |
| Mechanism | Rapid ventricular filling into a dilated or volume-overloaded ventricle. | Forceful atrial contraction into a stiff, non-compliant ventricle. |
| Associated with | Volume Overload / Systolic Dysfunction | Ventricular Stiffness / Diastolic Dysfunction |
Causes of Gallop Rhythms
Pathological gallops are signs of underlying cardiac conditions. The type of gallop points to a specific set of diseases.
Conditions Causing S3
- Systolic Heart Failure: The most common pathological cause.
- Mitral/Tricuspid Regurgitation: Causes volume overload.
- High-Output States: Anemia, hyperthyroidism.
- Physiological: Can be normal in children, young adults, and pregnancy.
Conditions Causing S4
- Hypertension: Leads to a stiff, hypertrophied ventricle.
- Aortic Stenosis: Causes pressure overload and hypertrophy.
- Myocardial Infarction: Scarring reduces compliance.
- Diastolic Heart Failure (HFpEF): A classic finding.
Interactive Auscultation Guide
Gallops are low-pitched sounds requiring specific techniques. Click each point to review key steps.
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Click a step to learn more
Select a numbered hotspot on the diagram.
Diagnosis and Management
Hearing a gallop prompts a diagnostic workup to find the cause. Management targets the underlying condition, not the sound itself.
Diagnostic Workup
- Echocardiogram (ECHO): The most crucial test to assess structure and function.
- ECG: Can show signs of hypertrophy or ischemia.
- BNP Blood Test: Elevated levels strongly suggest heart failure.
- Chest X-ray: May show an enlarged heart or lung fluid.
Management Principles
- Treat Heart Failure: Use diuretics, ACE inhibitors, beta-blockers, etc.
- Control Hypertension: Aggressively manage blood pressure to reduce stiffness.
- Address Valvular Disease: May require surgical intervention.
- Prognosis: A pathological gallop often indicates more severe disease and a poorer prognosis.
