Mechanisms of Fixed Splitting of the Second Heart Sound

Abstract

elinical anialysis of the secondll heart sound has oily recently been emphasized.1 An ullderstalldill(r of the normal second heart sound has increased the diagnoslie usefulness of its variations in congenital and acquired heart disease. In atrial septal (lefeet, as emphasized by Wood,( the aortic aid pulmnonic coniponelits of the second heart sou]d(l are not o0ly widely separated, but the split remains fixed throughout the respiratory cycle. The following study was designed to investigate the physiology of fixed splitting of the second heart sound in atrial septal defect and iii 3 other categories in which this pheliomeflonl has been observed-right and left bundle-braneh block with right ventricular failure, and mitral instufficiency-i with right ventricular failure. MAATERIALS AND) METHODSA total of 69 cases were studied. They consisted of 25 noriaal controls, 13 patients with atrial septal defect, 10 with pure mitral insufficiency, 11 with right bundle-branch block, and 10 with left bundle-branch block. The material included patients in the Georgetown University Medical Center and in the Clinic of Surgery, NXational Heart Institute, Bethesda. All patients had electrocardiograias and chest fluoroscopy. In the group with atrial septal defect the diagnoses were established by right heart catheterization. The group with pure initral insufficiency had left heart catheterization. The

How to count coughs? Counting by ear, the effect of visual data and the evaluation of an automated cough monitor

“…The sequences were selected by the investigator for the high density of coughs and differing underlying pathologies. Listeners were asked about known hearing problems and, in order to estimate experience of listening to closely spaced sounds, frequency of playing a musical instrument and confidence in detecting fixed splitting of the second heart sound on auscultation of the praecordium (minimum duration 0.02 s [21]). No specific training of how to count coughs was given; listeners were instructed only to count cough sounds whether occurring in isolation or as part of a bout of prolonged coughing.…”

The Mechanism of S2 (Second Heart Sound) Splitting in Normal Physiology and Congenital Heart Defects

“…The mechanism of the delayed closure of the pulmonary valve is due to increased ejection time of the right ventricle, caused by an increase in the venous return to the right atrium because of decreased intrathoracic pressure during inspiration [2,7,8]. There is also a decrease in the pressure of the pulmonary artery during inspiration, which may contribute to later closure of the pulmonary valve.…”

“…As stated above, several studies have demonstrated that surgical correction of the atrial septal defect leads to reversal of S2 splitting. Perloff and Harvey [8] showed that 11 of the 13 patients with atrial septal defects undergoing repair of the defect had a split-second heart sound on inspiration, and a single second heart sound on expiration after surgery.…”

Effect of the Valsalva Maneuver on the Second Heart Sound

“…In contradistinction, Valsalva release should continue to have an audible effect on the second heart sound in patients with right bundle branch block on the ECG, but without a hemodynamically significant ASD, or following successful ASD closure with a residual right bundle branch block [3], or in patients with partial anomalous pulmonary venous return and an intact atrial septum [4]. Thus, in addition to the established well-known bedside uses of the Valsalva maneuver in the presence of a murmur [5], it can be stated that the Valsalva maneuver should be incorporated into the routine of auscultation even when a murmur is absent.…”