A Ventricular Septal Defect (VSD) is primarily associated with a pansystolic murmur. However, other murmurs can be present depending on the size of the defect and its effects on cardiac blood flow.
Understanding the Primary VSD Murmur
The most characteristic heart murmur heard in a VSD is a pansystolic, or holosystolic, murmur. This means the murmur starts at the beginning of systole (when the ventricles contract) and continues throughout the entire duration of systole, ending only at the second heart sound (S2).
Key characteristics of the primary VSD murmur typically include:
- Timing: Pansystolic (occurring throughout systole).
- Location: Often loudest at the lower left sternal border.
- Radiation: Can radiate widely across the precordium.
- Quality: Usually described as harsh or blowing.
- Intensity: The intensity can vary. Surprisingly, smaller VSDs often have louder murmurs because the turbulent flow across a smaller opening is faster. Larger VSDs may have softer murmurs or even no murmur if the pressure difference between the ventricles is minimal.
Secondary Murmurs and Associated Sounds
In addition to the primary pansystolic murmur, other sounds may be present, particularly in larger VSDs or those causing significant blood flow changes:
Apical Mid-Diastolic Murmur (Rumble)
As highlighted in the provided reference: "An apical mid-diastolic murmur (rumble) may be heard due to increased flow across the mitral valve (relative mitral stenosis). This indicates that the VSD is large enough to cause excessive pulmonary blood flow and this clinically indicates congestive heart failure (CHF)."
This specific murmur is not the VSD murmur itself but rather a secondary finding caused by the increased volume of blood returning to the left atrium and flowing through the mitral valve during diastole. The massive increase in flow makes the mitral valve act like it's narrowed relative to the volume, causing a "rumble" sound. Its presence is a significant clinical indicator, suggesting a large VSD causing substantial shunting and potential complications like pulmonary hypertension and heart failure.
Other Potential Findings
- Loud P2: A loud pulmonary component of the second heart sound (P2) can indicate pulmonary hypertension, which may develop in large, unrepaired VSDs over time.
- Ejection systolic murmur: May be heard across the pulmonary valve due to increased flow into the pulmonary artery.
Summary of Murmur Types Associated with VSD
| Murmur Type | Timing | Location | Cause | Significance |
|---|---|---|---|---|
| Pansystolic Murmur | Systole | Lower left sternal border | Turbulent flow across the ventricular septal defect | Primary indicator of VSD |
| Apical Mid-Diastolic Rumble | Mid-Diastole | Apex | Increased flow across the mitral valve (relative mitral stenosis) | Indicates large VSD, high pulmonary flow, CHF |
| Pulmonary Ejection Murmur | Systole | Pulmonary area | Increased flow across the pulmonary valve | May occur with large VSD/high pulmonary flow |
Understanding these different murmurs and associated sounds helps clinicians assess the size and hemodynamic impact of a VSD.
