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A new technique for resection of the aortic arch
A new technique for resection of the aortic arch Carlos R. Lombardo, M.D. (by invitation), Antonio L. S. Machado, (by invitation), and James R. Jude, M.D., Miami, Fla.
Xusiform and dissecting aneurysms present complex problems in correction, as they re quire excision of a segment of the aorta, with preservation of its continuity by bridging the defect with a prosthesis. Circu lation to the brain, spinal cord, and abdomi nal viscera must be maintained during the procedure and the left ventricle will not tolerate the overloading which crossclamping the proximal aorta produces. Several techniques have been used clinically and in the laboratory to obviate these problems: hypothermia, temporary shunts of several kinds (with or without partial inflow occlusion), and extracorporeal circula tion.2"4· 6"14' 16· 17 Hypothermia, by decreasing the metabolic demands of the tissues, has permitted resec tion of the lower thoracic aorta, but the time of aortic occlusion is greatly limited. Paralysis and shock following release of the aortic occlusion and left ventricular failure have limited its use except in conjunction with bypass shunts or extracorporeal sys tems. With the advent of extracorporeal circu lation, thoracic aneurysms which were conFrom the Department of Thoracic and Cardiovascular Surgery, University of Miami, School of Medicine, Miami, Fla. Aided in part by Florida Heart Association and Heart Associations of Palm Beach and Martin Counties. Read at the Forty-fifth Annual Meeting of The American Association for Thoracic Surgery, New Orleans, La., March 29-31, 1965.
M.D.
sidered unresectable became resectable. The necessity of heparinization with this system markedly increases operative and post operative hemorrhage. Reoperation for con trol of hemorrhage and death have been detriments to this technique. Temporary bypass shunts from ascending-to-descending aorta have been used successfully by our selves and others. 3 · 6> 9 · 1 3 - 1 7 This technique is more time consuming but obviates the use of an extracorporeal circuit and hepa rinization. Success with aorta-to-aorta by pass shunt procedures with aneurysms involving the upper ascending, transverse, and descending aorta has led us to investi gate left ventricular-aortic shunts for use in replacement of the ascending aortic arch when only a short segment of the ascending aorta is uninvolved. Materials and methods Twenty-five mongrel dogs, ranging in weight from 12.7 to 23.6 kilograms, were anesthetized with pentobarbital sodium (30 mg./Kg.) and respiration was maintained by means of an endotracheal tube and an intermittent positive pressure respirator. A standard left fifth or sixth posterior lateral thoracotomy was performed. The pericardium was widely incised so that the heart could lay freely in the chest cavity. Left ventricular, left atrial, and central aortic pressures were measured by cannula677
Journal of
678
Lombardo, Machado, Jude
Thoracic and Cardiovascular Surgery
Aortic occlusion was accomplished by placing a vascular clamp across the ascend ing aorta just distal to the coronary ostia. Some animals had simple cross-clamping of the ascending aorta while others had division and suture and others had replacement of the ascending aorta by an appropriate size of woven Teflon graft. Survival of 48 hours without neurological deficits was taken as an end point and these dogs were then used as blood donors. Results
Fig. 1. Special designed Starr-Edwards aortic valve for bypass between left ventricular and descending thoracic aorta (supplied by Edwards Laboratories).
tion before and after the aorta was crossclamped. The pressures were recorded through Statham transducers. Dissection of the ascending aorta was carried out, sepa rating it from the pulmonary artery. A purse-string suture was placed either in the left atrial appendage or apex of the left ventricle for fixation of the ventricular end of the shunt. A specially designed Starr-Edwards aortic valve* (Fig. 1), fabricated within a woven Teflon prosthesis or within a small cylinder of siliconized Tygon and attached to a piece of woven Teflon graft, was used for the bypass. A partially occluding clamp was placed on the descending thoracic aorta and the woven Teflon graft was sutured to the vessel. Air was removed from the shunt by punching a small hole in the plastic graft. The elongated base of the valve or Tygon tubing attached to it was inserted into the ventricular cavity via its apex or by way of the left atrial appendage. Valves with orifices of VA inch and % inch in diameter were used. ♦Edwards Laboratories, Inc., 624 Dyer Road, Santa Ana, Calif.
Seven of the animals operated upon during the early part of the experiment were failures associated with now avoidable errors and are not included in Table I. These 7 animals died of arrhythmias due to irritation of the ventricular myocardium, usually secondary to malpositioning of the ventricular end of the shunt, or from uncon trollable hemorrhage from the graft-aorta suture line. Thirteen animals had bypass shunts inserted through the left atrial appendage and 5 through the apex of the left ventricle. Eight animals had simple cross-clamping of the ascending aorta, 2 had division and suture of the ascending aorta, and 8 had replacement of the ascend ing aorta with woven Teflon grafts. The aorta was clamped from periods of 21 to 100 minutes (Table I). Whole blood and normal saline were given to all animals that had replacement of the ascending aorta. These animals had no neurological abnormalities of any kind in the postoperative period. After the first sev en experiments only occasional premature ventricular contractions were encountered. The left atrial mean pressure changed only slightly during the bypass, averaging an in crease of 2.1 mm. Hg; with the left ventricu lar output diverted via the shunt, the average left ventricular-aortic gradient was 17 mm. Hg. In several of the animals, retrograde aortograms were made in the postoperative period (Fig. 2). Left ventricular, left atrial, and aortic pressure recordings were similar in all ani mals and Fig. 3 represents a typical experi-
Volume 50
Resection of aortic arch
Number 5
679
November, 1965
resistance to flow through the Vs inch diameter valve, even though the crosssectional area was 0.71 sq. cm. A similar rise in systemic arterial pressure following cross-clamping may possibly be explained by transfusion of the animal prior to crossclamping of the aorta. Elevation of the mean left atrial pressure with aortic occlusion varied directly with the left ventricular-aortic pressure gradient, but, even in the animals
ment. The left ventricular to aortic pressure gradient in this animal, after occlusion of the ascending aorta and allowing all of the left ventricular output to go via the shunt, resulted in a gradient of 16 mm. Hg. In the same animal the left atrial pressure increased only slightly, rising 2 mm. Hg throughout the entire procedure. Elevation of left ventricular pressure following occlusion of the ascending aorta represents increased Table I A ortie occlu Type of Dog Weight sion Procedure no. (Kg.) (min.) shunt* I 17 21 Cross-clamping LV-LA-Ao asc. aorta 11 15 23 Cross-clamping LV-LA-Ao asc. aorta III 16.8 30 Cross-clamping LV-LA-Ao asc. aorta IV 17 31 Cross-clamping LV-LA-Ao asc. aorta 12.7 V 45 Cross-clamping LV-LA-Ao asc. aorta 14 VI 60 Cross-clamping LV-LA-Ao asc. aorta 12.7 VII 35 Div. & suture LV-LA-Ao asc. aorta 23.6 VIII 21 Div. & suture LV-LA-Ao asc. aorta IX 16.3 65 Replacement of LV-LA-Ao asc. aorta & aortogram 19.3 X 100 Replacement of LV-LA-Ao asc. aorta 12.9 XI 55 Replacement of LV-LA-Ao asc. aorta & aortogram XII 13.1 75 Replacement of LV-LA-Ao asc. aorta XIII 15.9 80 Replacement of LV-LA-Ao asc. aorta xrv 13 30 Cross-clamping LV-Ao asc. aorta 13.1 XV 30 Cross-clamping LV-Ao asc. aorta XVI 17.2 80 Replacement of LV-Ao asc. aorta XVII 19.5 50 Replacement of LV-Ao asc. aorta XVIII 19 35 Replacement of LV-Ao asc. aorta Legend: LV = left ventricle. LA = left atrium. Ao
Pressure (mm. Hg) Aorta undamped LV
Ao
Aorta cross-clamped
LA
LV
Ao
120/0
100/80
LA
Gra dient
— 9
11
20
105/0
105/70
153/0
153/132
110/0
110/75
11
100/0
95/65
12
5
95/0
95/75
10
116/0
100/75
12
16
98/0
98/10
8
120/0
105/65
10
15
115/6
115/60
137/11 128/90
115/5
115/107
110/13
108/74
11
127/0
109/80
13
18
148/56 148/120
10
175/10 165/135
110/0
110/60
9
108/0
88.5/60
13
30.5
132/0
132/80
10
160/0
120/76
14
40
125/0
125/80
10
125/0
105/70
12
20
140/0
160/90
9
120/0
105/74
10
15
6 80
Journal of
Lombardo, Machado, Jude
Thoracic and Cardiovascular Surgery
with shunt diameters of VA inch and cross section of 0.32 sq. cm., the elevation was not great and varied from 1 to 2 mm. Hg higher. This indicates that the myocardium, even though doing slightly more work, was able to function quite well while obtaining its coronary flow from the very short seg-
ment of the ascending aorta during diastole. This is in agreement with studies of Sarnoff and associates15 which showed that chronic ventriculo-descending aortic shunts in ani mals did not appear to alter the ability of the heart to respond to the natural tenden cies to run, play, or fight. The aorta was cross-clamped in some experiments for over an hour, which per mitted resection and prosthetic replacement of the ascending aorta (Table I). The dura tion of the proximal aortic occlusion did not affect the ultimate outcome, and pressure measurements (Table I) did not change significantly from their previous levels. The occurrence of premature ventricular con tractions in animals with long occlusion times were noted to be more frequent near the end of the period of occlusion. Evalua tion of the animals in the 48 hour postopera tive period revealed no differences in their behavior, motility, or sensation, in spite of long periods of occlusion. There was no appreciable hemorrhage noted from or in the heart, whether the shunt was inserted into the ventricle through the left atrial appendage or through the apex of the left ventricle. Aortograms performed on several animals postoperatively revealed no abnormalities. The aortogram in Fig. 2 illustrates a slight indention where the distal suture line of the Teflon prosthesis joins the aorta just proxi mal to the brachiocephalic trunk.
Fig. 2. Postoperative aortogram in animal XI after replacement of the ascending aorta. Note indentation of the distal aortic suture line proximal to the brachiocephalic trunk.
Discussion Surgical treatment for aneurysms of the thoracic aorta has evolved in the last 15
mrnHg.
Fig. 3. Left ventricular, central aortic, and left atrial mean pressures before and after occlusion of the ascending aorta.
Volume 50
Resection of aortic arch
Number 5
681
November, 1965
years, with several techniques now advo cated for therapy of these life-threatening lesions. Saccular aneurysms with narrow necks do not represent a major problem any longer. Tuffier,18 in the early part of the century, attacked one of these aneurysms of the aortic arch by tying the neck with a ligature and leaving the sac in place; the patient died 13 days later from hemorrhage secondary to necrosis of the sac and slippage of the ligature. Cooley and De Bakey5 and Bahnson1 have reported sucessful tangential resection of saccular aneurysms of the ascending aorta and aortic arch with lateral aortorrhaphy. The introduction of extracorporeal circu lation added an new approach to treatment of thoracic aneurysms. 7 · 8 Unfortunately, hemorrhage in the operative and postopera tive period, secondary to the effects of heparinization and damage to the formed elements of the blood by the perfusion tech niques, have frequently led to the need for reoperation for control of hemorrhage or have even resulted in death. The data presented indicate that the pres ently described technique can be utilized to resect diseased ascending aortas and replace them with prosthetic grafts without the use of extracorporeal circulation and heparini zation if there is a short segment of aorta that can be left above the coronary ostia. Death of 7 of the animals early in our experimental efforts can be definitely asso ciated with unfamiliarity with the procedure. The remaining animals, even though many of them required transfusion because of leaks at the graft to the aorta suture line, maintained good coronary perfusion and hemodynamics while the left ventricular out put was diverted via the shunt. We believe that the omission of anticoagulation is probably the most important factor in this experimental study. Replacement of the aortic arch in dogs with the aid of partial left heart bypass is very often met with exsanguinating hemorrhage in the postopera tive period, whereas, if resection is accom plished by the use of a woven Teflon prosthetic graft shunt from the left ventricle
to the descending aorta, blood loss is not a problem. Similar experiments by Sarnoff, but with the use of a different type of valved aortic shunt, indicated that this approach could be applicable to resection of the ascending aortic arch. Jeger,12 in a report cited by Küttner in 1923, successfully performed a left ventricular-to-aortic chronic shunt on a dog that lived for 4 days utilizing a segment of vein with a normal vein valve interposed. Normal neurologic function after the pro cedure indicated adequate cerebral perfu sion and absence of embolie phenomenon. In some of Sarnoff's chronic animals, em bolism was a problem. The short length of time of use of this prosthetic device in the ventricle of our animals may account for the absence of peripheral emboli. The study of animals with the chronic type of shunt and the use of this technique for replacement of the aortic valve is now being undertaken in our laboratory. Summary A new technique for replacement of the aortic arch by means of a temporary left ventricle to descending thoracic aorta shunt has been described. There was no need for anticoagulation of the animals. Left ventric ular-to-aortic pressure gradients were mini mal during bypass of the ascending aorta.
REFERENCES 1 Bahnson, H. T. : Considerations in the Excision of Aortic Aneurysms, Ann. Surg. 138: 377, 1953. 2 Beattie, E. J., Jr., Adovasio, D., Keshishian, J. M., and Blades, B.: Refrigeration in Experi mental Surgery of the Aorta, Surg., Gynec. & Obst. 96: 711, 1953. 3 Björk, V. O.: Successful Replacement of the Total Aortic Arch for Aneurysm, J. THORACIC & CARDIOVAS. SURG. 45: 817,
1963.
4 Carrel, A.: On the Experimental Surgery of the Thoracic Aorta and the Heart, Ann. Surg. 52: 83, 1910. 5 Cooley, D. A., and De Bakey, M. E.: Surgical Considerations of Intrathoracic Aneurysms of the Aorta and Great Vessels, Ann. Surg. 135: 660, 1952. 6 Cooley, D. A., and De Bakey, M. E.: Resection
Journal of
6 8 2 Lombardo, Machado, Jude
Thoracic and Cardiovascular Surgery
of the Thoracic Aorta With Replacement by Homograft for Aneurysms and Constrictive Lesions, J. THORACIC SURG. 29: 66, 1955.
7 Cooley, D. A., and De Bakey, M. E.: Resection of Entire Ascending Aorta in Fusiform Aneurysm Using Temporary Cardiac Bypass, J. A. M. A. 162: 1158, 1956. 8 Cooley, D. A., De Bakey, M. E., and Morris, G. C , Jr.: Controlled Extracorporeal Circula tion in Surgical Treatment of Aortic Aneurysm, Ann. Surg. 146: 473, 1957. 9 Derrick, J. R., and Spencer, D. C : Technical Considerations in the Resection of Aneurysms of the Ascending Aorta, Transverse Arch and Upper Descending Thoracic Aorta, Am. J. Surg. 103: 536, 1962. 10 Hardin, C. A., Batchelder, T. L., and Shafer, P. W.: The Temporary Use of Polyethylene Shunts in the Resection and Homologous Graft Replacement of the Aortic Arch in the Dog, Surgery 32: 219, 1952. 11 Hufnagel, C. A., and Gross, R. E.: Coarctation of the Aorta: Experimental Studies Regarding its Correction, New England J. Med. 233: 287, 1945. 12 Jeger, cited by Küttner, H.: Chirurgische Operationslehre, ed. 5, Leipzig, 1923, Barth, Vol. 2.
13 Muller, W. H., Jr., Warren, W. D., and Blanton, F. S., Jr.: A Method for Resection of Aortic Arch Aneurysms, Ann. Surg. 151: 225, 1960. 14 Pontius, R. G., Brockman, H. L., Hardy, E. G., Cooley, D. A., and De Bakey, M. E.: The Use of Hypothermia in the Prevention of Paraplegia Following Temporary Aortic Oc clusion: Experimental Observations, Surgery 36: 33, 1954. 15 Sarnoff, S. J., Donovan, T. J., and Case, R. B.: The Surgical Relief of Aortic Stenosis by Means of Apical-Aortic Valvular Anastomosis, Circulation 11: 564, 1955. 16 Shafer, P. W., and Hardin, C. A.: The Use of Temporary Polyethylene Shunts to Permit Occlusion, Resection and Frozen Homologous Graft Replacement of Vital Vessel Segments, Surgery 31: 186, 1952. 17 Stranahan, A., Alley, R. D., Sewell, W. H., and Kaunsel, H. W.: Aortic Arch Resection and Grafting for Aneurysm Employing an Ex ternal Shunt, J. THORACIC SURG. 29: 54, 1955.
18 Tuffier, Th.: Intervention chirurgicale directe pour un anéurysme de la crosse de l'aorte: Ligature du sac, La presse méd. 10: 267, 1902. (For Discussion, see page 689)
Xusiform and dissecting aneurysms present complex problems in correction, as they re quire excision of a segment of the aorta, with preservation of its continuity by bridging the defect with a prosthesis. Circu lation to the brain, spinal cord, and abdomi nal viscera must be maintained during the procedure and the left ventricle will not tolerate the overloading which crossclamping the proximal aorta produces. Several techniques have been used clinically and in the laboratory to obviate these problems: hypothermia, temporary shunts of several kinds (with or without partial inflow occlusion), and extracorporeal circula tion.2"4· 6"14' 16· 17 Hypothermia, by decreasing the metabolic demands of the tissues, has permitted resec tion of the lower thoracic aorta, but the time of aortic occlusion is greatly limited. Paralysis and shock following release of the aortic occlusion and left ventricular failure have limited its use except in conjunction with bypass shunts or extracorporeal sys tems. With the advent of extracorporeal circu lation, thoracic aneurysms which were conFrom the Department of Thoracic and Cardiovascular Surgery, University of Miami, School of Medicine, Miami, Fla. Aided in part by Florida Heart Association and Heart Associations of Palm Beach and Martin Counties. Read at the Forty-fifth Annual Meeting of The American Association for Thoracic Surgery, New Orleans, La., March 29-31, 1965.
M.D.
sidered unresectable became resectable. The necessity of heparinization with this system markedly increases operative and post operative hemorrhage. Reoperation for con trol of hemorrhage and death have been detriments to this technique. Temporary bypass shunts from ascending-to-descending aorta have been used successfully by our selves and others. 3 · 6> 9 · 1 3 - 1 7 This technique is more time consuming but obviates the use of an extracorporeal circuit and hepa rinization. Success with aorta-to-aorta by pass shunt procedures with aneurysms involving the upper ascending, transverse, and descending aorta has led us to investi gate left ventricular-aortic shunts for use in replacement of the ascending aortic arch when only a short segment of the ascending aorta is uninvolved. Materials and methods Twenty-five mongrel dogs, ranging in weight from 12.7 to 23.6 kilograms, were anesthetized with pentobarbital sodium (30 mg./Kg.) and respiration was maintained by means of an endotracheal tube and an intermittent positive pressure respirator. A standard left fifth or sixth posterior lateral thoracotomy was performed. The pericardium was widely incised so that the heart could lay freely in the chest cavity. Left ventricular, left atrial, and central aortic pressures were measured by cannula677
Journal of
678
Lombardo, Machado, Jude
Thoracic and Cardiovascular Surgery
Aortic occlusion was accomplished by placing a vascular clamp across the ascend ing aorta just distal to the coronary ostia. Some animals had simple cross-clamping of the ascending aorta while others had division and suture and others had replacement of the ascending aorta by an appropriate size of woven Teflon graft. Survival of 48 hours without neurological deficits was taken as an end point and these dogs were then used as blood donors. Results
Fig. 1. Special designed Starr-Edwards aortic valve for bypass between left ventricular and descending thoracic aorta (supplied by Edwards Laboratories).
tion before and after the aorta was crossclamped. The pressures were recorded through Statham transducers. Dissection of the ascending aorta was carried out, sepa rating it from the pulmonary artery. A purse-string suture was placed either in the left atrial appendage or apex of the left ventricle for fixation of the ventricular end of the shunt. A specially designed Starr-Edwards aortic valve* (Fig. 1), fabricated within a woven Teflon prosthesis or within a small cylinder of siliconized Tygon and attached to a piece of woven Teflon graft, was used for the bypass. A partially occluding clamp was placed on the descending thoracic aorta and the woven Teflon graft was sutured to the vessel. Air was removed from the shunt by punching a small hole in the plastic graft. The elongated base of the valve or Tygon tubing attached to it was inserted into the ventricular cavity via its apex or by way of the left atrial appendage. Valves with orifices of VA inch and % inch in diameter were used. ♦Edwards Laboratories, Inc., 624 Dyer Road, Santa Ana, Calif.
Seven of the animals operated upon during the early part of the experiment were failures associated with now avoidable errors and are not included in Table I. These 7 animals died of arrhythmias due to irritation of the ventricular myocardium, usually secondary to malpositioning of the ventricular end of the shunt, or from uncon trollable hemorrhage from the graft-aorta suture line. Thirteen animals had bypass shunts inserted through the left atrial appendage and 5 through the apex of the left ventricle. Eight animals had simple cross-clamping of the ascending aorta, 2 had division and suture of the ascending aorta, and 8 had replacement of the ascend ing aorta with woven Teflon grafts. The aorta was clamped from periods of 21 to 100 minutes (Table I). Whole blood and normal saline were given to all animals that had replacement of the ascending aorta. These animals had no neurological abnormalities of any kind in the postoperative period. After the first sev en experiments only occasional premature ventricular contractions were encountered. The left atrial mean pressure changed only slightly during the bypass, averaging an in crease of 2.1 mm. Hg; with the left ventricu lar output diverted via the shunt, the average left ventricular-aortic gradient was 17 mm. Hg. In several of the animals, retrograde aortograms were made in the postoperative period (Fig. 2). Left ventricular, left atrial, and aortic pressure recordings were similar in all ani mals and Fig. 3 represents a typical experi-
Volume 50
Resection of aortic arch
Number 5
679
November, 1965
resistance to flow through the Vs inch diameter valve, even though the crosssectional area was 0.71 sq. cm. A similar rise in systemic arterial pressure following cross-clamping may possibly be explained by transfusion of the animal prior to crossclamping of the aorta. Elevation of the mean left atrial pressure with aortic occlusion varied directly with the left ventricular-aortic pressure gradient, but, even in the animals
ment. The left ventricular to aortic pressure gradient in this animal, after occlusion of the ascending aorta and allowing all of the left ventricular output to go via the shunt, resulted in a gradient of 16 mm. Hg. In the same animal the left atrial pressure increased only slightly, rising 2 mm. Hg throughout the entire procedure. Elevation of left ventricular pressure following occlusion of the ascending aorta represents increased Table I A ortie occlu Type of Dog Weight sion Procedure no. (Kg.) (min.) shunt* I 17 21 Cross-clamping LV-LA-Ao asc. aorta 11 15 23 Cross-clamping LV-LA-Ao asc. aorta III 16.8 30 Cross-clamping LV-LA-Ao asc. aorta IV 17 31 Cross-clamping LV-LA-Ao asc. aorta 12.7 V 45 Cross-clamping LV-LA-Ao asc. aorta 14 VI 60 Cross-clamping LV-LA-Ao asc. aorta 12.7 VII 35 Div. & suture LV-LA-Ao asc. aorta 23.6 VIII 21 Div. & suture LV-LA-Ao asc. aorta IX 16.3 65 Replacement of LV-LA-Ao asc. aorta & aortogram 19.3 X 100 Replacement of LV-LA-Ao asc. aorta 12.9 XI 55 Replacement of LV-LA-Ao asc. aorta & aortogram XII 13.1 75 Replacement of LV-LA-Ao asc. aorta XIII 15.9 80 Replacement of LV-LA-Ao asc. aorta xrv 13 30 Cross-clamping LV-Ao asc. aorta 13.1 XV 30 Cross-clamping LV-Ao asc. aorta XVI 17.2 80 Replacement of LV-Ao asc. aorta XVII 19.5 50 Replacement of LV-Ao asc. aorta XVIII 19 35 Replacement of LV-Ao asc. aorta Legend: LV = left ventricle. LA = left atrium. Ao
Pressure (mm. Hg) Aorta undamped LV
Ao
Aorta cross-clamped
LA
LV
Ao
120/0
100/80
LA
Gra dient
— 9
11
20
105/0
105/70
153/0
153/132
110/0
110/75
11
100/0
95/65
12
5
95/0
95/75
10
116/0
100/75
12
16
98/0
98/10
8
120/0
105/65
10
15
115/6
115/60
137/11 128/90
115/5
115/107
110/13
108/74
11
127/0
109/80
13
18
148/56 148/120
10
175/10 165/135
110/0
110/60
9
108/0
88.5/60
13
30.5
132/0
132/80
10
160/0
120/76
14
40
125/0
125/80
10
125/0
105/70
12
20
140/0
160/90
9
120/0
105/74
10
15
6 80
Journal of
Lombardo, Machado, Jude
Thoracic and Cardiovascular Surgery
with shunt diameters of VA inch and cross section of 0.32 sq. cm., the elevation was not great and varied from 1 to 2 mm. Hg higher. This indicates that the myocardium, even though doing slightly more work, was able to function quite well while obtaining its coronary flow from the very short seg-
ment of the ascending aorta during diastole. This is in agreement with studies of Sarnoff and associates15 which showed that chronic ventriculo-descending aortic shunts in ani mals did not appear to alter the ability of the heart to respond to the natural tenden cies to run, play, or fight. The aorta was cross-clamped in some experiments for over an hour, which per mitted resection and prosthetic replacement of the ascending aorta (Table I). The dura tion of the proximal aortic occlusion did not affect the ultimate outcome, and pressure measurements (Table I) did not change significantly from their previous levels. The occurrence of premature ventricular con tractions in animals with long occlusion times were noted to be more frequent near the end of the period of occlusion. Evalua tion of the animals in the 48 hour postopera tive period revealed no differences in their behavior, motility, or sensation, in spite of long periods of occlusion. There was no appreciable hemorrhage noted from or in the heart, whether the shunt was inserted into the ventricle through the left atrial appendage or through the apex of the left ventricle. Aortograms performed on several animals postoperatively revealed no abnormalities. The aortogram in Fig. 2 illustrates a slight indention where the distal suture line of the Teflon prosthesis joins the aorta just proxi mal to the brachiocephalic trunk.
Fig. 2. Postoperative aortogram in animal XI after replacement of the ascending aorta. Note indentation of the distal aortic suture line proximal to the brachiocephalic trunk.
Discussion Surgical treatment for aneurysms of the thoracic aorta has evolved in the last 15
mrnHg.
Fig. 3. Left ventricular, central aortic, and left atrial mean pressures before and after occlusion of the ascending aorta.
Volume 50
Resection of aortic arch
Number 5
681
November, 1965
years, with several techniques now advo cated for therapy of these life-threatening lesions. Saccular aneurysms with narrow necks do not represent a major problem any longer. Tuffier,18 in the early part of the century, attacked one of these aneurysms of the aortic arch by tying the neck with a ligature and leaving the sac in place; the patient died 13 days later from hemorrhage secondary to necrosis of the sac and slippage of the ligature. Cooley and De Bakey5 and Bahnson1 have reported sucessful tangential resection of saccular aneurysms of the ascending aorta and aortic arch with lateral aortorrhaphy. The introduction of extracorporeal circu lation added an new approach to treatment of thoracic aneurysms. 7 · 8 Unfortunately, hemorrhage in the operative and postopera tive period, secondary to the effects of heparinization and damage to the formed elements of the blood by the perfusion tech niques, have frequently led to the need for reoperation for control of hemorrhage or have even resulted in death. The data presented indicate that the pres ently described technique can be utilized to resect diseased ascending aortas and replace them with prosthetic grafts without the use of extracorporeal circulation and heparini zation if there is a short segment of aorta that can be left above the coronary ostia. Death of 7 of the animals early in our experimental efforts can be definitely asso ciated with unfamiliarity with the procedure. The remaining animals, even though many of them required transfusion because of leaks at the graft to the aorta suture line, maintained good coronary perfusion and hemodynamics while the left ventricular out put was diverted via the shunt. We believe that the omission of anticoagulation is probably the most important factor in this experimental study. Replacement of the aortic arch in dogs with the aid of partial left heart bypass is very often met with exsanguinating hemorrhage in the postopera tive period, whereas, if resection is accom plished by the use of a woven Teflon prosthetic graft shunt from the left ventricle
to the descending aorta, blood loss is not a problem. Similar experiments by Sarnoff, but with the use of a different type of valved aortic shunt, indicated that this approach could be applicable to resection of the ascending aortic arch. Jeger,12 in a report cited by Küttner in 1923, successfully performed a left ventricular-to-aortic chronic shunt on a dog that lived for 4 days utilizing a segment of vein with a normal vein valve interposed. Normal neurologic function after the pro cedure indicated adequate cerebral perfu sion and absence of embolie phenomenon. In some of Sarnoff's chronic animals, em bolism was a problem. The short length of time of use of this prosthetic device in the ventricle of our animals may account for the absence of peripheral emboli. The study of animals with the chronic type of shunt and the use of this technique for replacement of the aortic valve is now being undertaken in our laboratory. Summary A new technique for replacement of the aortic arch by means of a temporary left ventricle to descending thoracic aorta shunt has been described. There was no need for anticoagulation of the animals. Left ventric ular-to-aortic pressure gradients were mini mal during bypass of the ascending aorta.
REFERENCES 1 Bahnson, H. T. : Considerations in the Excision of Aortic Aneurysms, Ann. Surg. 138: 377, 1953. 2 Beattie, E. J., Jr., Adovasio, D., Keshishian, J. M., and Blades, B.: Refrigeration in Experi mental Surgery of the Aorta, Surg., Gynec. & Obst. 96: 711, 1953. 3 Björk, V. O.: Successful Replacement of the Total Aortic Arch for Aneurysm, J. THORACIC & CARDIOVAS. SURG. 45: 817,
1963.
4 Carrel, A.: On the Experimental Surgery of the Thoracic Aorta and the Heart, Ann. Surg. 52: 83, 1910. 5 Cooley, D. A., and De Bakey, M. E.: Surgical Considerations of Intrathoracic Aneurysms of the Aorta and Great Vessels, Ann. Surg. 135: 660, 1952. 6 Cooley, D. A., and De Bakey, M. E.: Resection
Journal of
6 8 2 Lombardo, Machado, Jude
Thoracic and Cardiovascular Surgery
of the Thoracic Aorta With Replacement by Homograft for Aneurysms and Constrictive Lesions, J. THORACIC SURG. 29: 66, 1955.
7 Cooley, D. A., and De Bakey, M. E.: Resection of Entire Ascending Aorta in Fusiform Aneurysm Using Temporary Cardiac Bypass, J. A. M. A. 162: 1158, 1956. 8 Cooley, D. A., De Bakey, M. E., and Morris, G. C , Jr.: Controlled Extracorporeal Circula tion in Surgical Treatment of Aortic Aneurysm, Ann. Surg. 146: 473, 1957. 9 Derrick, J. R., and Spencer, D. C : Technical Considerations in the Resection of Aneurysms of the Ascending Aorta, Transverse Arch and Upper Descending Thoracic Aorta, Am. J. Surg. 103: 536, 1962. 10 Hardin, C. A., Batchelder, T. L., and Shafer, P. W.: The Temporary Use of Polyethylene Shunts in the Resection and Homologous Graft Replacement of the Aortic Arch in the Dog, Surgery 32: 219, 1952. 11 Hufnagel, C. A., and Gross, R. E.: Coarctation of the Aorta: Experimental Studies Regarding its Correction, New England J. Med. 233: 287, 1945. 12 Jeger, cited by Küttner, H.: Chirurgische Operationslehre, ed. 5, Leipzig, 1923, Barth, Vol. 2.
13 Muller, W. H., Jr., Warren, W. D., and Blanton, F. S., Jr.: A Method for Resection of Aortic Arch Aneurysms, Ann. Surg. 151: 225, 1960. 14 Pontius, R. G., Brockman, H. L., Hardy, E. G., Cooley, D. A., and De Bakey, M. E.: The Use of Hypothermia in the Prevention of Paraplegia Following Temporary Aortic Oc clusion: Experimental Observations, Surgery 36: 33, 1954. 15 Sarnoff, S. J., Donovan, T. J., and Case, R. B.: The Surgical Relief of Aortic Stenosis by Means of Apical-Aortic Valvular Anastomosis, Circulation 11: 564, 1955. 16 Shafer, P. W., and Hardin, C. A.: The Use of Temporary Polyethylene Shunts to Permit Occlusion, Resection and Frozen Homologous Graft Replacement of Vital Vessel Segments, Surgery 31: 186, 1952. 17 Stranahan, A., Alley, R. D., Sewell, W. H., and Kaunsel, H. W.: Aortic Arch Resection and Grafting for Aneurysm Employing an Ex ternal Shunt, J. THORACIC SURG. 29: 54, 1955.
18 Tuffier, Th.: Intervention chirurgicale directe pour un anéurysme de la crosse de l'aorte: Ligature du sac, La presse méd. 10: 267, 1902. (For Discussion, see page 689)