A mechanism of a cardiac murmur with respiratory variation in a patient with straight back syndrome

Abstract

A 20-year-old male without any symptoms was referred for heart murmur on a medical examination. A thrill was palpable at the upper left sternal border. His cardiac murmur showed respiratory variation. The systolic murmur was louder (Levine grade IV/VI) during expiration and diminished during inspiration (Levine grade I/VI). He was thin and had a narrow thoracic cage in the anteroposterior direction due to straight back syndrome (SBS). An echocardiogram and a right ventriculogram showed changes in the diameter of the right ventricular outflow tract (RVOT) on respiration. During expiration, the RVOT was compressed and narrow, while it was expanded during inspiration. Cardiac catheterization demonstrated a 10-mmHg of pressure gradient across the RVOT during expiration but no pressure gradient during inspiration. Thus, respiratory compression to the RVOT by a narrow thoracic cage due to SBS was the cause of the cardiac murmur with respiratory alterations. Our case highlights the importance of physical examination, including an inspection of the patient's physique. <Learning objective: When examining a patient with a cardiac murmur, respiratory alterations of cardiac murmurs should be auscultated. In these cases, straight back syndrome would be one of the differential diagnoses and should be considered. During a physical examination, inspection of the patient's physique is also important.>

Chest wall reconstruction with digitally designed materials for straight back syndrome with tracheal stenosis: a case report

“…The straight thoracic spine narrows the distance to the anterior chest wall, which reduces the mediastinal space, leading to compression of the heart, great vessels, esophagus, trachea etc. (1)(2)(3)(4)(5).…”

“…The right ventricular outflow tract is located adjacent to the sternum, and is the first site of compression. There are various symptoms when the heart is compressed (3)(4)(5), and many SBS patients are initially diagnosed for heart problems, so SBS is also called false heart disease (3). The aorta is a structure with continuous positive pressure, and strong pressure resistance, so it is not easy to change its shape under external pressure.…”

“…Straight back syndrome (SBS) is an autosomal dominant disorder, first reported by Rawlings in 1960 (1,2). It is mainly characterized by the disappearance of the physiological curvature of the spine, straightness of the upper thoracic vertebra, shortening of the anteroposterior diameter of the thorax, and compression of the structures in the mediastinum, resulting in variety of symptoms (3)(4)(5)(6). The fundamental cause of the disease is spinal, and the symptoms are mainly concentrated on the respiratory and cardiovascular systems.…”

The Clinical Manifestation of Straight Back Syndrome in Echocardiogram Performance

“…Previous studies have suggested that the mechanism of murmur in patients with straight back syndrome is, on the one hand, due to a decrease in deep inhalation and an increase in deep exhalation [4]. On the other hand, it may be related to the mechanism of the murmur that the spine and sternum lose the normal physiological Radian so that the heart is close to the sternum, the right ventricular out ow tract is squeezed and the aortic root is squeezed.…”

Related mechanisms and research progress in straight back syndrome

“…In a recent study of 1569 randomly selected patients who underwent 64-row chest computed tomography (CT) scans, it was found that CT could identify signs that were not visible on X-ray films, leading to a more accurate diagnosis of SBS and a better correlation of clinical symptoms with imaging findings, as has also been reported in studies overseas. Matsumoto et al [ 33 ] recently used echocardiography and right ventricular angiography to uncover the mechanism underlying the change in heart murmur with respiration, which they found to be due to variation in the diameter of the right ventricular outflow tract during respiration. It was not until 2017 that Marbella et al [ 34 ] investigated the statistical correlation between SBS and MVP and revealed that 27% of patients with severe mitral valve regurgitation caused by MVP also had SBS.…”