What maneuver is most likely to increase the intensity of a midsystolic murmur in an asymptomatic 14-year-old boy with a dual-peaked carotid pulse and a faint midsystolic murmur, whose father experienced sudden cardiac arrest (sudden cardiac death)?

From the Guidelines

The most likely maneuver to increase the murmur intensity in this patient is E. Valsalva strain phase. This patient presents with findings consistent with hypertrophic cardiomyopathy (HCM), including a family history of sudden cardiac death, a dual upstroke carotid pulse, strong apical impulse, and a midsystolic murmur at the apex and left sternal border. In HCM, the murmur is caused by dynamic left ventricular outflow tract obstruction. The Valsalva maneuver reduces venous return to the heart, decreasing left ventricular volume, which narrows the outflow tract and worsens the obstruction, thereby intensifying the murmur. Conversely, maneuvers that increase preload (squatting, supine leg raise, supine position) would decrease the murmur by increasing ventricular filling and widening the outflow tract. Sustained handgrip increases afterload but doesn't significantly affect the murmur in HCM. This patient should undergo further cardiac evaluation including echocardiography to confirm the diagnosis of HCM, given the concerning family history of sudden cardiac arrest.

Some key points to consider in this case include:

• The patient's physical examination findings, such as the dual upstroke carotid pulse and strong apical impulse, are consistent with HCM 1.
• The Valsalva maneuver is a useful diagnostic tool for HCM, as it can exacerbate the left ventricular outflow tract obstruction and increase the intensity of the murmur 1.
• Echocardiography is an essential diagnostic test for HCM, as it can provide detailed information about the left ventricular outflow tract and the mitral valve 1.
• The patient's family history of sudden cardiac death is a significant risk factor for HCM, and further evaluation is necessary to confirm the diagnosis and assess the risk of sudden cardiac death 1.
• The management of HCM typically involves a combination of medical therapy, lifestyle modifications, and possibly surgical intervention, depending on the severity of the disease and the patient's symptoms 1.
• It is essential to distinguish HCM from other causes of left ventricular outflow tract obstruction, such as valvular or supravalvular stenosis, and to evaluate the patient for other cardiac conditions that may be associated with HCM, such as mitral regurgitation or atrial fibrillation 1.

From the Research

Evaluation of Systolic Murmurs

The patient's symptoms and physical examination results suggest the presence of a systolic murmur, which may be indicative of an underlying cardiac condition. To determine the most likely maneuver to increase the murmur intensity, we can consider the following options:

• A. Squatting
• B. Supine leg raise
• C. Supine position from standing
• D. Sustained handgrip
• E. Valsalva strain phase

Maneuvers to Increase Murmur Intensity

According to the studies, the Valsalva maneuver is widely used to provoke left ventricular outflow tract obstruction in hypertrophic cardiomyopathy (HCM) 2, 3, 4. The Valsalva maneuver can increase the murmur intensity in patients with HCM by increasing the left ventricular outflow tract gradient. Additionally, the study by 5 found that the murmur of hypertrophic cardiomyopathy was distinguished from all other murmurs by an increase in intensity with the Valsalva maneuver.

Recommended Maneuver

Based on the evidence, the Valsalva strain phase (option E) is the most likely maneuver to increase the murmur intensity in this patient. This is because the Valsalva maneuver is a well-established method for provoking left ventricular outflow tract obstruction in HCM, and the patient's symptoms and physical examination results are consistent with this condition 2, 5, 3, 4.

Other Considerations

Other maneuvers, such as squatting, supine leg raise, and sustained handgrip, may also be used to evaluate the patient's murmur, but the Valsalva maneuver is the most specific and sensitive method for diagnosing HCM 5, 4. The study by 6 also found that postprandial resting and stress echocardiography can be useful in unmasking latent left ventricular outflow tract obstruction in patients with HCM. However, this is not directly relevant to the question of which maneuver is most likely to increase the murmur intensity.

Some key points to consider when evaluating systolic murmurs include:

• The Valsalva maneuver is a useful method for provoking left ventricular outflow tract obstruction in HCM 2, 3, 4
• The murmur of hypertrophic cardiomyopathy is distinguished from all other murmurs by an increase in intensity with the Valsalva maneuver 5
• Other maneuvers, such as squatting and sustained handgrip, may also be used to evaluate the patient's murmur, but the Valsalva maneuver is the most specific and sensitive method for diagnosing HCM 5, 4