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Is the shunt patent?
Is the Shunt Patent? J. G. Schutz, MBBCh, M. J. Antunes, MD, MMed, PhD, and R. H. Kinsley, MBBCh, FCS (SA) Division of Cardiothoracic Surgery, University of the Witwatersrand, Johannesburg,South Africa
A novel technique for auscultating an aortopulmonary shunt murmur utilizing the principle of conduction of sounds through a closed air system is described. (Ann Thorac Surg 1989;47:472)
T
he principle of the conduction of heart sounds and murmurs through an air column for auscultation was popularized by Laennec and Theophile [l]and resulted in the modern stethoscope. This allows selective, enhanced auscultation of cardiac events. Another application of this principle is the esophageal stethoscope much used by pediatric anesthetists. We have made an interesting, if obvious, observation that utilizes this principle in assessing the patency of systemic-pulmonary artery shunts, specifically, the Blalock-Taussig shunt and its modified form. Anxiety regarding the patency of a shunt is common in the early postoperative period; this is due to varying saturations, respiratory variables, hemodynamic lability, and, often, difficulty in auscultating the shunt murmur. The ideal in systemic-pulmonary artery shunts is early extubation, but in our experience the infants are often intubated for at least 18 to 24 hours. During this period the shunt can be reliably auscultated by disconnecting the endotracheal tube from the ventilator and applying, occlusively, the bell of a stethoscope to the open endotracheal tube connection briefly during a quiescent phase of respiration (Fig 1).Because of the proximity of the shunt to the major airways, the trachea and bronchi, and the excellent conduction of the sound by the air column, the shunt murmur is often well heard by comparison with Accepted for publication Nov 4, 1988. Address correspondence to Dr Schutz, Division of Cardiothoracic Surgery, University of the Witwatersrand Medical School, York Rd, Parktown 2193, Johannesburg, Republic of South Africa.
0 1989 by The Society of Thoracic Surgeons
Fig I. The bell of the stethoscope is applied occlusively to the open endotruched tube connection.
precordial auscultation, or audible when it is not so by standard auscultation. It is recommended that after intubation in the operating room, and before operation, auscultation be performed to establish a baseline, as a ductal shunt murmur or collateral flow murmur may be present. Auscultation is again done at the end of the procedure and periodically in the intensive care unit to confirm patency. We have found this an. extremely useful and reassuring sign over the past 2 years, and recommend its use as an adjunct in assessing the status of the uncertain shunt. To our knowledge, this is an original observation. Its application could be extended to monitor the status of the ductal shunt in other situations of congenital heart disease and in neonates with persistent respiratory distress syndrome due to a patent cluctus arteriosus.
Reference 1. Laennec R, Theophile I-[. A treatise on diseases of the chest. Forbes J, translator. London: T & G Underwood, 1821.
0003-4975/89/$3.50
A novel technique for auscultating an aortopulmonary shunt murmur utilizing the principle of conduction of sounds through a closed air system is described. (Ann Thorac Surg 1989;47:472)
T
he principle of the conduction of heart sounds and murmurs through an air column for auscultation was popularized by Laennec and Theophile [l]and resulted in the modern stethoscope. This allows selective, enhanced auscultation of cardiac events. Another application of this principle is the esophageal stethoscope much used by pediatric anesthetists. We have made an interesting, if obvious, observation that utilizes this principle in assessing the patency of systemic-pulmonary artery shunts, specifically, the Blalock-Taussig shunt and its modified form. Anxiety regarding the patency of a shunt is common in the early postoperative period; this is due to varying saturations, respiratory variables, hemodynamic lability, and, often, difficulty in auscultating the shunt murmur. The ideal in systemic-pulmonary artery shunts is early extubation, but in our experience the infants are often intubated for at least 18 to 24 hours. During this period the shunt can be reliably auscultated by disconnecting the endotracheal tube from the ventilator and applying, occlusively, the bell of a stethoscope to the open endotracheal tube connection briefly during a quiescent phase of respiration (Fig 1).Because of the proximity of the shunt to the major airways, the trachea and bronchi, and the excellent conduction of the sound by the air column, the shunt murmur is often well heard by comparison with Accepted for publication Nov 4, 1988. Address correspondence to Dr Schutz, Division of Cardiothoracic Surgery, University of the Witwatersrand Medical School, York Rd, Parktown 2193, Johannesburg, Republic of South Africa.
0 1989 by The Society of Thoracic Surgeons
Fig I. The bell of the stethoscope is applied occlusively to the open endotruched tube connection.
precordial auscultation, or audible when it is not so by standard auscultation. It is recommended that after intubation in the operating room, and before operation, auscultation be performed to establish a baseline, as a ductal shunt murmur or collateral flow murmur may be present. Auscultation is again done at the end of the procedure and periodically in the intensive care unit to confirm patency. We have found this an. extremely useful and reassuring sign over the past 2 years, and recommend its use as an adjunct in assessing the status of the uncertain shunt. To our knowledge, this is an original observation. Its application could be extended to monitor the status of the ductal shunt in other situations of congenital heart disease and in neonates with persistent respiratory distress syndrome due to a patent cluctus arteriosus.
Reference 1. Laennec R, Theophile I-[. A treatise on diseases of the chest. Forbes J, translator. London: T & G Underwood, 1821.
0003-4975/89/$3.50