A heart murmur is an unusual sound heard during a heartbeat, distinct from the typical “lub-dub” sounds. These sounds can sometimes indicate an underlying heart condition. A ventricular septal defect (VSD) murmur is a common occurrence among various types of heart murmurs. This particular murmur signals the presence of a structural issue within the heart. While some heart murmurs are considered harmless, a VSD murmur points to a specific anatomical variation that warrants attention.
Understanding Ventricular Septal Defects
A ventricular septal defect (VSD) refers to a hole in the septum, the muscular wall that divides the heart’s two lower chambers, known as the ventricles. Normally, the left side of the heart pumps oxygen-rich blood to the body, while the right side pumps oxygen-poor blood to the lungs. With a VSD, blood can flow abnormally from the higher-pressure left ventricle to the lower-pressure right ventricle, leading to extra blood being pumped to the lungs.
This abnormal blood flow through the hole creates the characteristic sound of a VSD murmur. VSDs can occur in different locations within the septum. Common types include perimembranous VSDs, located in the upper section of the septum, and muscular VSDs, found in the lower, more muscular part. The specific location of the defect, along with its size, influences the degree of blood shunting and the resulting impact on heart function.
Characteristics of the Murmur
The murmur associated with a ventricular septal defect is typically described as “holosystolic” or “pansystolic,” meaning it is heard throughout the entire contraction phase of the heart, known as systole. This continuous sound arises because blood flows constantly from the high-pressure left ventricle to the lower-pressure right ventricle through the defect during this period. The murmur is often characterized as loud and harsh.
Healthcare providers typically listen for this murmur using a stethoscope, and it is usually best heard along the lower left sternal border, near the breastbone. The size of the VSD can influence the loudness of the murmur in a counterintuitive way. Smaller defects often produce louder, harsher murmurs due to the higher pressure gradient and increased turbulence of blood flow through a restricted opening. In contrast, very large VSDs may result in softer murmurs or even no murmur at all because the large opening allows blood to flow more freely with less turbulence.
Associated Symptoms and Complications
Symptoms of a ventricular septal defect vary with the hole’s size. Small VSDs may cause no symptoms, with the murmur being the only sign. Larger defects can lead to issues, particularly in infants. Common symptoms include difficulty feeding, poor weight gain, rapid breathing, shortness of breath, and excessive sweating during feeding. These signs often appear between 4 to 6 weeks of age as pulmonary vascular resistance decreases, increasing blood flow through the defect.
Untreated large VSDs can lead to complications. One complication is pulmonary hypertension, high blood pressure in the lung arteries due to increased blood flow and pressure. This can lead to permanent damage to the lung’s blood vessels. Another complication is heart failure, where the heart struggles to pump enough blood due to increased workload. Other complications include irregular heart rhythms and, rarely, endocarditis, an infection of the heart’s inner lining.
Diagnosis and Management
Diagnosis of a ventricular septal defect often begins when a healthcare provider detects a heart murmur during a routine physical examination. The murmur’s location, loudness, and quality provide initial clues about a heart issue. To confirm diagnosis and gather more information, an echocardiogram is the primary diagnostic tool. This heart ultrasound creates moving pictures, allowing doctors to visualize the defect’s presence, size, and location, and assess blood flow and pressure within the heart chambers.
Additional tests, such as an electrocardiogram (ECG) to evaluate heart electrical activity or a chest X-ray to check for an enlarged heart or fluid in the lungs, may be performed for a more comprehensive assessment. In some instances, cardiac catheterization might be used for further information about heart structures and pressures, especially if other tests are inconclusive.
VSD management is tailored to the defect’s size and symptoms. For small VSDs, especially in infants, observation is often recommended, as many defects (particularly muscular and perimembranous types) close spontaneously, often by age 2 to 6 years. If symptoms develop, medication may be prescribed to manage issues like heart failure, including diuretics to reduce fluid buildup or digoxin to help the heart pump more efficiently. Surgical closure, typically recommended for larger defects or those causing symptoms or complications, often involves open-heart surgery to patch the hole. In select cases, a less invasive catheter-based procedure may be an option, guiding a small device through a blood vessel to close the defect.