Pulmonary Blood Flow Measurements Following Vena Cava-to-Pulmonary Artery Anastomosis

Transcription

1 Pulmonary Blood Flow Measurements Following Vena Cava-to-Pulmonary Artery Anastomosis Francis Robicsek, M.D., Walter P. Scott, M.D., Norris B. Harbold, M.D., Harry K. Daugherty, M.D., and Donald C. Mullen, M.D. ABSTRACT The distribution of pulmonary blood flow was investigated in 2 patients 13 and 9 years following vena cava-to-pulmonary artery anastomosis. Angiographic and radioactive flow studies revealed a wide-open vena cava-topulmonary artery anastomosis which became larger proportional to the patient s growth. The passage of contrast material through the lung was swift and unimpeded; however, perfusion of the apical portion of the right lung appeared less than satisfactory. There was a complete separation between the systems of the superior and inferior caval veins, and contrast material and radioactive albumin injected into the system of the superior caval vein entered the right lung exclusively. On the basis of these observations, it is our opinion that if vena cava-topulmonary artery anastomosis is done with a proper operative indication and a satisfactory surgical technique, one should not expect late development of intercaval collaterals and decrease in the efficiency of the vena cava-topulmonary artery shunt. A nastomosis between the superior caval vein and the right pulmonary artery was recommended by Carlon and his associates [ 1, 21 in 1950 for palliative treatment of certain congenital heart conditions. Our experimental and clinical studies [3-211 have shown that this method has the following advantages over other types of systemic-to-pulmonary anastomotic procedures: (1) it does not place the extra burden of a left-toright shunt on the already overloaded heart; (2) blood pressure in the pulmonary artery is not increased; (3) pure venous blood is supplied to the lungs; and (4) the volume work of the right ventricle is diminished. Despite the fact that the procedure has been applied in a number of patients with good results, it has never really become a popular operation. The cause of this might be the apparent irreversibility of the operation and the likelihood of late development of collateral circulation between the two From the Department of Thoracic and Cardiovascular Surgery and the Heincman Medical Research Laboratory, Charlotte Memorial Hospital, Charlotte, N.C. Accepted for publication July 12, Address reprint requests to Dr. Robicsek, The Sanger Clinic, 1929 Randolph Rd., Charlotte, N.C THE ANNALS OF THORACIC SURGERY

2 Blood Flow Following Cava-to-Pulmonary Artery Anastomosis caval veins, which would decrease the effectiveness of the anastomosis. While recent experience indicates that both the superior vena cava and the pulmonary artery can be either reanastomosed or left in situ without untoward effects when the original anomaly is repaired, the matter of late development of intercaval venous collaterals has never been investigated. We have examined this problem in 2 patients who underwent end-toend anastomosis between the distal end of the divided superior vena cava and the similarly transected right pulmonary artery I3 and 9 years ago, respectively. The azygos vein was also ligated in both patients. The results of this study are presented below. Clinical Materia.1 and Study Methods Our first patient, then an ll-year-old boy, was operated upon in 1958 because of complex cyanotic heart disease. The malformation consisted of transposition of the great vessels, pulmonary stenosis, and a large atrial septa1 defect. The patient, whose physical activity was severely restricted by fatigue and exertional dyspnea, responded very favorably to the operation. The hemoglobin content of the blood and arterial oxygen saturation, measured before operation as 15.4 gm. and 82%, are now 13.6 gm. and 91%, respectively. He is gainfully employed and has no difficulty in performing normal activities. The second patient, a 42-year-old man, was first seen by us in Examination at that time revealed an advanced form of tetralogy of Fallot with a long infundibular pulmonary stenosis and severe hypoplasia of the main pulmonary artery. Because of the patient's age and the extent of the lesion, a vena cava-to-pulmonary artery anastomosis was performed in lieu of complete repair. As with the previous patient, this patient also showed great improvement following operation. His blood,hemoglobin decreased from 16.8 to 14.6 gm., the arterial oxygen saturation changed from 84 to 89%, and he performs light physical work and supports his family. At the time of their readmission to the hospital, both patients underwent angiographic studies. Contrast material injected into the subclavian vein rapidly passed the vena cava-to-pulmonary artery anastomosis and filled the right pulmonary vessels. The following observations are thought especially worthy of mention. (1) The superior vena cava and right pulmonary artery appeared to be a single vessel with a smooth, continuous contour and no evidence of narrowing at the anastomotic site. Comparing the initial angiograms of Patient 1 with those taken three years after operation, it was apparent that the anastomosis had grown proportionally with the vascular structures involved. (2) The passage of contrast material through the right lung was swift, and most of the contrast material cleared the lung within 4 seconds. (3) The vessels to the upper lobe were poorly

3 ROBICSEK ET AL. A B FIG. 1. Angiographic studies in Patient 1 (A) and Patient 2 (B) 13 and 9 years, respectively, following vena cava-to-pulmonary artery anastomosis. The contrast material injected into the subclavian vein rapidly passes the vena caoa-to-pulmonary artery anastomosis and clears the right lung. There is absolutely no evidence of intercaval collaterals. (The clocks show the passage of time in seconds.) 130 THE ANNALS OF THORACIC SURGERY

4 Blood Flow Following Cava-to-Pulmonary Artery Anastomosis visualized in both patients. (4) There was absolutely no evidence of interconnecting collaterals between the systems of the superior and inferior vena cava (Fig. 1). Lung scanning and imaging were also used to investigate the pattern of pulmonary blood flow and to detect possible intercaval collaterals. Scanning and imaging were performed following selective injections of 200 microcuries of iodine 131 macroaggregated albumin into the right antecubital and left femoral veins using an Ohio Nuclear dual probe scanner" and a Nuclear Chicago Pho-Gamma I1 camera.? Pho-Gamma scintiphotographs in Patient 1 showed heavy perfusion of the lower two-thirds of the right lung following injection of the radioactive material into the antecubital vein. There was absolutely no spillage over into the left lung. The injection was repeated 30 minutes later into the femoral vein. Scintiphotographs at this time showed retardation of radioactive albumin in the right lung and homogeneous perfusion throughout the entire left lung field (Fig. 2). Rectilinear scans in Patient 2 following injection of macroaggregated albumin showed heavy perfusion through the lower half and poor perfusion through the upper portion of the right lung. Again there was absolutely no spillage over of radioactive material into the left lung. Injection into the femoral vein was carried out two days later. Rectilinear scans at that time showed complete clearing of radioactive material on the right side and good perfusion throughout the entire left lung (Fig. 3). FIG. 2. Patient 1. Scintiphotographs show heavy perfusion throughout the lower twothirds of the right lung following right antecubital vein injection of 200 microcuries of iodine 131 macroaggregated albumin (left) and difluse light perfusion 30 minutes later following left femoral vein injection with the same dose (right). *Ohio Nuclear Corp., Cleveland, Ohio.?Nuclear CHICAGO Corp., Durham, N.C. VOt. 15, NO. 2, FEBRUARY, 1973 lgl

5 ROBICSEK ET AL. FIG. 3. Patient 2. Rectilinear scan following injection of 200 microcuries of iodine 131 macroaggregated albumin into the right antecubital vein shows heavy perfusion of the right lower lung and poor perfusion of the apical region (left). Scan performed after left femoral vein injection 48 hours later (right) shows complete interim clearing of the right lung and good perfusion of the left lung. Comment Vena cava-to-pulmonary artery anastomosis, like any other operation, carries the risk of potential complications. Persistent cyanosis and swelling of the upper body, chylothorax, and development of extensive intercaval collaterals have been mentioned as unwanted sequelae peculiar to this operation. Development of venous collaterals is especially important because it significantly decreases the amount of blood flowing through the vena cavato-pulmonary artery anastomosis, thus making the operation ineffective. This very important complication can be largely eliminated if appropriate precautions are observed. 1. Vena cava-to-pulmonary artery anastomosis should not be performed in patients whose pulmonary flow is increased or whose pulmonary artery pressure is above normal values (or who have both conditions). Abnormally high pulmonary vascular resistance reflects most unfavorably on the blood flow through the anastomosis and inevitably leads to a disastrous situation WI. 2. An abnormally small right pulmonary artery may prevent the performance of an anastomosis of sufficient caliber [4]. Anastomosis of the superior caval vein to a hypoplastic right pulmonary artery is one of the 132 THE ANNALS OF THORACIC SURGERY

6 Blood Flow Following Cava-to-Pulmonary Artery Anastomosis commonest causes of retrograde venous stasis and extensive intercaval collateral circulation following vena cava-to-pulmonary artery shunt. In such cases, anastomotic operations of other types, such as the Blalock-Taussig or Waterston procedure, are more suitable because the large systemic artery-topulmonary artery pressure gradient Allows better blood flow through a smaller anastomotic lumen. 3. The anastomosis should be performed with extreme care so as not to narrow the lumen of the vessels involved. We prefer end-to-end anastomosis to end-to-side vascular connection because of its more favorable flow pattern [4]. Special care should be exerted to tailor the vessels to the proper length to prevent kinking or overstretching. 4. Management of the azygos vein during vena cava-to-pulmonary artery anastomosis i s a factor of utmost importance. In 1963 we demonstrated [I41 that the development of azygos steal syndrome is a tragic and most, frustrating event following this operation. The azygcs is the greatest collateral channel between the two caval veins. Although it serves as an important safety valve while the superior vena cava is occluded during performance of the anastomosis, it is imperative to ligate it after the procedure is completed, as it steals blood that would otherwise go through the anastomosis into the pulmonary circulation. The ligation may be done immediately after completion of the anastomosis, as is our custom, or by delayed ligature, as advised by Edwards and colleagues [3]. References 1. Carlon, C. A., Mondini, P. G., and DeMarchi, R. Su une nuova anastomosi vasale per le terapia cirurgica di alcuni vizi cardiovasculari. G. Ztal. Chir. 6:760, Carlon, C. A., Mondini, P. G., and DeMarchi, R. Surgical treatment of some cardiovascular disease (a new vascular anastomosis). J. Znt. Coll. Surg. 16:1, Edwards, W. S., and Bargeron, L. M. Superior cava to right pulmonary artery shunt for tricuspid arteries in an infant. Surgery 49:205, Glenn, W. W. L. Circulatory bypass of the right side of the heart: IV. Shunt between superior vena cava and distal right pulmonary artery. N. Engl. J. Med. 259:117, Hurwitt, E. S., Young, D., and Escher, D. J. W. The rationale of anastomosis of the right auricular appendage to the pulmonary artery in the treatment of tricuspid atresia. J. Thorac. Surg. 30:503, Robicsek, F., Daugherty, H. K., Tam, W., Sanger, P. W., and Bagby, E. A new procedure for the palliation of transposition of the great vessels. Ann. Thorac. Surg. 7:21, Robicsek, F., Magistro, R., Foti, E., Robicsek, L., and Sanger, P. W. Venacava pulmonary artery anastomosis for vascularization of the lung. J. Thorac. Surg. 35:440, Robicsek, F., and Robicsek, L. K. Is the right heart a necessary organ? Complete bypass of the right heart: Observations after four years. Rev. Argent. Angiol. 33:66, VOL. 15, NO. 2, FEBRUARY,

7 ROBICSEK ET AL. 9. Robicsek, F., Sanger, P. W., Gallucci, V., and Bagby, E. Long-term complete circulatory exclusion of the right side of the heart. Am. J. Cardiol. 18:867, Robicsek, F., Sanger, P. W., Gallucci, V., and Daugherty, H. K. Long-term circulatory exclusion of the right heart. Surgery 59:421, Robicsek, F., Sanger, P. W., Moore, M., Daugherty, H. K., Robicsek, L. K., and Bagby, E. Observations following four years of complete circulatory exclusion of the right heart. Ann. Thorac. Surg. 8:530, Robicsek, F., Sanger, P. W., and Taylor, F. H. Three year follow-up of a patient with transposition of the great vessels, atrial septal defect and pulmonary stenosis treated by vena cava-pulmonary artery anastomosis. J. Thorac. Cardiouasc. Surg. 44:817, Robicsek, F., Sanger, P. W., Taylor, F. H., and Daugherty, H. K. Peripheral stricture of the pulmonary artery treated by cava-pulmonary anastomosis. Ann. Surg. 160:1066, Robicsek, F., Sanger, P. W., Taylor, F. H., and Najib, A. The azygos steal syndrome in cava pulmonary anastomosis. Ann. Surg. 158: 1007, Robicsek, F., Sanger, P. W., Taylor, F. H., Najib, A., and Tavana, M. Complete bypass of the right heart. Am. Heart J. 66:792, Robicsek, F., Temesvari, T., and Kadar, R. L. A new method for the treatment of congenital heart disease associated with impaired pulmonary circulation. Acta Med. Scand. 154: 151, Sanger, P. W., Robicsek, F., Robicsek, L. K., and Gallucci, V. The clinical application of cava-pulmonary anastomosis. Dis. Chest 48: 145, Sanger, P. W., Robicsek, F., and Taylor, F. H. Vena cava-pulmonary artery anastomosis: 111. Successful operation in a case of complete transposition of great vessels with interatrial septal defect and pulmonary stenosis. J. Thorac. Cardiouasc. Surg. 38: 167, Sanger, P. W., Robicsek, F., Taylor, F. H., and Gallucci, V. Observations on partial and complete circulatory exclusion of the right heart. J. Cardiouasc. Surg. (Torino) 6:30, Sanger, P. W., Robicsek, F., Taylor, F. H., Najib, A., Tavana, M., and Gallucci, V. Is the right heart an absolutely necessary organ? Bull. SOC. Znt. Chir. 5-6:645, Sanger, P. W., Taylor, F. H., Robicsek, F., and Ibrahim, K. Stenosis of the origin of the right pulmonary artery. J. Thorac. Cardiouasc. Surg. 48: 124, Schumaker, H. B. Discussion of Hurwitt et al. [5] at 35th Annual Meeting, American Association for Thoracic Surgery, Atlantic City, N. J., April 24, THE ANNALS OF THORACIC SURGERY