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Ann Thorac Surg 1999;68:2306-2309
© 1999 The Society of Thoracic Surgeons

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Original Articles

Adjustable tourniquet to manipulate pulmonary blood flow after Norwood operations

^a Department of Cardiothoracic Surgery, Johannes Gutenberg-University Hospitals, Mainz, Germany
^b Department of Pediatric Cardiology, Johannes Gutenberg-University Hospitals, Mainz, Germany
^c Department of Anesthesiology, Johannes Gutenberg-University Hospitals, Mainz, Germany

Address reprint requests to Dr Schmid, Department of Cardiothoracic and Vascular Surgery, Regensburg University Hospital, Franz-Josef-Strauss-Allee 11, D-93042 Regensburg, Germany
e-mail: franz-xaver.schmid{at}klinik.uni-regensburg.de

	Abstract

Top Abstract Introduction Patients and methods Results Comment References

 
Background. Survival after first-stage palliative Norwood operations for single ventricle with systemic outflow obstruction is mainly dependent on a balanced ratio of pulmonary blood flow to systemic blood flow. Here we report the clinical results using a modified technique that allows a controlled systemic-to-pulmonary shunt flow to prevent pulmonary overcirculation.

Methods. From 1995 to 1998, of 26 infants undergoing first-stage palliative Norwood operations, 7 had placement of an adjustable tourniquet around a modified right Blalock-Taussig shunt.

Results. Hospital survival was 20 of 26 patients (77%). All 7 patients in whom snaring of the shunt was indicated survived. Two patients underwent repeated adjustment, in 5 patients the tourniquet could be removed during delayed sternal closure, and 2 patients were discharged with the shunt partially snared.

Conclusions. The snare-controlled systemic-to-pulmonary shunt allows improved hemodynamic stability after reconstructive surgery for hypoplastic left heart syndrome or other similar complex cardiac defects by reducing the risk of pulmonary overcirculation. It is simple and rapidly executed. The option of graded banding of the shunt depending on the hemodynamic situation increases flexibility and safety after cardiopulmonary bypass or at any time in the postoperative period.

	Introduction

Top Abstract Introduction Patients and methods Results Comment References

 
Recent advances in the perioperative management of classic hypoplastic left heart syndrome or its variants have allowed staged palliation with improved results [1–3]. After first-stage palliation of all forms of single ventricle associated with systemic outflow and arch obstruction, pulmonary and systemic circulations continue to be supplied from the single ventricular chamber in a parallel arrangement. Survival is mainly dependent on a ratio of pulmonary blood flow to systemic blood flow at or near unity. Inadequate pulmonary blood flow (pulmonary blood flow to systemic blood flow ratio less than 1) results in hypoxemia with subsequent metabolic instability and myocardial dysfunction. The most common critical situation postoperatively is a pulmonary blood flow to systemic blood flow ratio greater than 1 with pulmonary overcirculation, systemic hypoperfusion, and metabolic acidosis. A variety of measures to prevent pulmonary overcirculation have been described, including ventilatory adjustments, medical therapy to reduce systemic vascular resistance, or surgical shunt revision back in the operating room [4–6]. In some cases these efforts were only partially and transiently successful in achieving circulatory and metabolic homeostasis. We report the use of an adjustable tourniquet placed around the systemic-to-pulmonary shunt to control pulmonary blood flow after stage I palliation for hypoplastic left heart syndrome and other similar complex congenital heart defects.

	Patients and methods

Top Abstract Introduction Patients and methods Results Comment References

 
From January 1995 through December 1998, 26 infants underwent first-stage palliative Norwood operations at the Department of Cardiothoracic Surgery, Johannes Gutenberg University Hospitals, Mainz, Germany. There were 17 boys and 9 girls, with an average weight of 3.1 kg (range, 2.2 to 4.5 kg). Diagnosis was confirmed only by echocardiography. In 20 patients there was classic hypoplastic left heart syndrome with hypoplasia of the aortic annulus (< 5 mm), mitral annulus (< 10 mm), and a non–apex-forming left ventricle. Six patients were considered to have similar single ventricle physiology with aortic outflow obstruction (functional hypoplastic left heart syndrome; Table 1). In these patients aortic arch reconstruction with incorporation of the pulmonary valve for systemic outflow was required. The operation was performed at a mean age of 9.1 ± 3.7 days (range, 4 to 42 days).

View larger version (18K): [in this window] [in a new window]   Fig 1. Schematic display of the operative technique. The adjustable tourniquet is placed around the systemic-to-pulmonary shunt. (Ao = homograft-augmented aorta; PA = pulmonary artery; RA = right atrium.)

We performed delayed sternal closure in all patients after first-stage palliative Norwood procedures. The study protocol was approved by the human investigation committee of our institution. Written informed consent was obtained from the parents of each patient.

	Results

Top Abstract Introduction Patients and methods Results Comment References

 
Total mortality in this series was 27% (7 of 26 patients). The operative mortality was 23% (6 of 26 patients). The causes of death included technical problems in 1 patient, sudden cardiovascular collapse in the intensive care unit in 2 infants, severe atrioventricular valve insufficiency in 2 patients, and shunt occlusion in 1 patient. The circulatory arrest time averaged 65 ± 12 minutes (range, 49 to 84 minutes), with a mean total bypass time of 195 ± 37 minutes (range, 106 to 249 minutes). One late death occurred (4%). This patient had a cardiovascular collapse during feeding at home at the age of 10 weeks.

All patients entered a three-stage palliative repair schedule. At present, 14 of the 19 survivors have undergone an intermediate hemi-Fontan operation. The age at operation was 7.6 ± 1.4 months (range, 3.8 to 13.6 months). No deaths (early or late) have occurred, and currently 3 patients have successfully completed their final palliation by undergoing a completion Fontan operation at 14, 20, and 24 months of age.

All 7 patients who received an adjustable tourniquet around the systemic-to-pulmonary shunt during the Norwood operation survived. There was no significant difference in the preoperative hemodynamic profile between patients who needed and patients who did not need snaring of the shunt. Hemodynamic data before and after placement of a tourniquet are presented in Table 2. Two patients had the tourniquet adjusted more than once in the postoperative period. This was performed at the bedside in the intensive care unit and remained in place until a hemi-Fontan procedure was performed. In 5 patients, the snare could be removed during delayed sternal closure. All patients are doing well; they are in New York Heart Association class II and have an average saturation of 81%.

	Comment

Top Abstract Introduction Patients and methods Results Comment References

A variety of measures to counteract pulmonary overcirculation have been described. Inspired carbon dioxide has proven to be effective in preventing or treating instability arising from changes of the ratio of pulmonary vascular resistance to systemic vascular resistance [5]. An increase in PaCO₂ will result in a redistribution of blood flow from the pulmonary circulation to the systemic circulation [8]. Jobes and associates [5] emphasized that in some cases when pulmonary overcirculation is already established the use of inspired CO₂ and other interventions to increase pulmonary vascular resistance, such as hypoventilation, reduction in inspired oxygen fraction, and hyperventilation with increased positive end-expiratory pressure, were not successful and resulted in an attempt to mechanically control pulmonary perfusion. Pharmacologic manipulations (eg, sodium nitroprusside) to decrease systemic vascular resistance are often limited when systemic blood pressure is dependent on inotropic support and large doses of inotropic drugs have to be avoided.

The technique that is reported here offers several advantages. Snaring of the shunt results in an immediate reduction of pulmonary blood flow and does not need much time to demonstrate effectiveness. The space of time to reach an equilibrium is considerably shorter in comparison with respiratory changes. The tourniquet can be tightened in stages to adapt the diameter of the shunt adequately to the hemodynamic demands. At least during the early postoperative period, partial reopening of the tourniquet is feasible by removing one or two clips. Delayed sternal closure is not necessarily required when a tourniquet is placed. In case of primary chest closure, the snare is left in place and buried underneath the linea alba. If indicated later on, it can be easily retrieved under the lower part of the thoracotomy incision under local anesthesia, and its placement provides rapid control of shunt flow. In fact, the snare can also be placed on the innominate artery proximal to the origin of the shunt or even on central shunts. When placed on the subclavian artery distal to the shunt anastomosis, it should theoretically improve pulmonary blood flow in rare instances with diminished pulmonary perfusion. During our experience this was not necessary. Our clinical observation of patients with a snare-controlled systemic-to-pulmonary shunt has demonstrated a marked decrease in heart size, common atrial pressure, and systemic arterial saturation. This was also the case when snaring was performed in the intensive care unit under hemodynamic and echocardiographic control.

In general, the tourniquet can be removed easily during secondary sternal closure. Stabilization of the hemodynamic situation usually takes place within 2 to 3 days after operation. We were able to remove the snare during sternal closure between the second and seventh postoperative day in 5 patients without hemodynamic compromise. In 2 patients we left the tourniquet in place when the systemic saturation exceeded 85% after complete reopening of the shunt. It was removed with the shunt during subsequent hemi-Fontan operation without problems.

This experience is confirmed by others who applied this concept for creation of an adjustable interatrial communication in a modified Fontan procedure [9,10]. We share the concern about the use of a foreign body. Infection is not uncommon in these patients, often occurring some days postoperatively. In our practice, antibiotics are maintained for 2 weeks or, in any case, through chest closure and removal of drainage tubes. Persistent infection was not realized in our patients but should prompt early reinvestigation.

It could be argued that a small shunt that is additionally snared should result in inadequate pulmonary blood flow with persistent heavy cyanosis (saturation less than 75%) during the late postoperative period when the patient outgrows the shunt. In our experience, arterial saturation improved from 5% to 10% during the early postoperative period when capillary leakage resolved and the patient started to breath spontaneously. Moreover, a banding of the shunt by a 7-0 Prolene can be reopened by interventional balloon angioplasty, if necessary. We have not found a snared shunt to be a problem postoperatively after hospital discharge of the patients. The intermediate hemi-Fontan operation was performed early at an average age of 7.6 months. In fact, this may be to the child’s advantage by protecting the pulmonary vascular system with a view toward performing a later Fontan circulation.

In conclusion, the technical modification as applied in this small series of patients may be beneficial in establishing balance of pulmonary-to-systemic resistance after first-stage palliative Norwood operations. The use of an adjustable tourniquet around the systemic-to-pulmonary shunt is a technically straightforward way to manipulate pulmonary blood flow with minimal intervention. Regardless of the underlying morphologic diagnosis, the main goal of the Norwood procedure, namely, maintenance of circulatory and metabolic homeostasis at an arterial oxygen saturation of 80% to 85%, is completely achieved. This modification may be useful in all patients with single ventricle and systemic outflow obstruction and is of particular advantage in high-risk patients, such as those with labile pulmonary vascular resistance and impaired ventricular function.

	Footnotes

 
This article has been selected for the open discussion forum on the STS Web site: http://www.sts.org/section/atsdiscussion/

	References

Top Abstract Introduction Patients and methods Results Comment References

 

1. Gutgesell H.P., Massaro T.A. Management of hypoplastic left heart syndrome in a consortium of university hospitals. Am J Cardiol 1995;76:809-811.[Medline]
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3. Weldner P.W., Myers J.L., Gleason M.M., et al. The Norwood operation and subsequent Fontan operation in infants with complex congenital heart disease. J Thorac Cardiovasc Surg 1995;109:654-662.[Abstract/Free Full Text]
4. Jonas R.A., Lang P., Hansen D., Hickey P., Castaneda A.R. First-stage palliation of hypoplastic left heart syndrome. The importance of coarctation and shunt size. J Thorac Cardiovasc Surg 1986;92:6-13.[Abstract]
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7. Pigott J.D., Murphy J.D., Barber G., Norwood W.I. Palliative reconstructive surgery for hypoplastic left heart syndrome. Ann Thorac Surg 1988;45:122-128.[Abstract]
8. Morray J.P., Lynn A.M., Mansfield P.B. Effect of pH and PCO₂ on pulmonary and systemic hemodynamics after surgery in children with congenital heart disease and pulmonary hypertension. J Pediatr 1988;1132:474-479.
9. Laks H., Ardehali A., Grant P.W., et al. Modification of the Fontan procedure. Superior vena cava to left pulmonary artery connection and inferior vena cava to right pulmonary artery connection with adjustable atrial septal defect. Circulation 1995;91:2943-2947.[Abstract/Free Full Text]
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This Article Abstract Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Add to Personal Folders Download to citation manager Author home page(s): Yeong-Hoon Choi Hellmut Oelert Permission Requests Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Schmid, F. X. Articles by Oelert, H. Search for Related Content PubMed PubMed Citation Articles by Schmid, F. X. Articles by Oelert, H.