From the Guidelines
The physical exam finding described is a murmur heard at the left upper sternal border (LUSB) in the sitting position, which is suggestive of hypertrophic obstructive cardiomyopathy (HOCM) due to the positional accentuation of the murmur. This location is significant as it's a common auscultation point for certain cardiac murmurs, particularly pulmonic stenosis, aortic stenosis, or hypertrophic cardiomyopathy. When a murmur is specifically noted to be better heard in the sitting position, this often suggests it may be related to HOCM, as the obstruction to left ventricular outflow typically increases in this position. The sitting position reduces venous return to the heart, decreasing left ventricular volume, which can exacerbate the dynamic obstruction in HOCM. This positional accentuation is an important diagnostic clue that helps differentiate between various cardiac conditions. Further cardiac evaluation including echocardiography would typically be warranted to confirm the specific cause of this murmur, as recommended by the ACC/AHA guidelines for the management of patients with valvular heart disease 1. Some key points to consider in the evaluation of this patient include:
- The intensity of the murmur and its response to various physiological maneuvers, such as the Valsalva maneuver or squatting 1
- The presence or absence of cardiac and noncardiac symptoms and other findings on physical examination that suggest the murmur is clinically significant 1
- The use of echocardiography to evaluate asymptomatic patients with murmurs associated with other abnormal cardiac physical findings or murmurs associated with an abnormal ECG or chest X-ray 1
From the Research
Physical Exam Findings
- A murmur heard at the left upper sternal border (LUSB) in a sitting position can be an indication of a pathologic heart condition 2.
- The intensity and characteristics of the murmur can provide clues about the underlying condition, with harsh, pansystolic murmurs of intensity grade > or = 3 being more likely to be associated with pathology 2.
Murmur Characteristics
- A systolic ejection murmur (SEM) can be a sign of aortic stenosis, but it is not specific for this condition and can be heard in a large proportion of elderly patients 3.
- The presence of a SEM, combined with other abnormal physical findings, can help determine whether a patient should be referred for further evaluation, such as echocardiography 3.
Diagnostic Evaluation
- Echocardiography can be used to evaluate patients with suspected aortic stenosis, and can provide information about left ventricular function, left atrial volume, and right ventricular function 4.
- Tissue Doppler imaging (E/e') and pulmonary capillary wedge pressure (PCWP) can be used to assess left-sided heart filling pressures, but their correlation in patients with severe aortic stenosis is not significant 5.