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Simple hypothermic retrograde cerebral perfusion during aortic arch replacement
Simple hypothermic retrograde cerebral perfusion during aortic arch replacement A preliminary report on two successful cases We recently found that hypothermic retrograde cerebral perfusion can be performed by simply elevating the central venous pressure in Trendelenburg's position while the aortic arch is open. In this technique, with an occlusion balloon in the descending aorta, deep hypothermic perfusion of the lower half of the body is performed as oxygen-rich venous blood supplies the brain. Two successful cases are reported: one of dissecting aortic aneurysm, DeBakey type II, with a true aortic arch aneurysm, in a 53-year-old woman, and one of acute aortic dissection, DeBakey type I, in a 53-year-old man. With the brain under retrograde perfusion at a rectal temperature of 15° C and a central venous pressure of 15 mm Hg, replacement of the ascending to the descending aorta in the former case and to the proximal aortic arch in the latter case was successful. Cerebral circulatory arrest times were 81 and 65 minutes, respectively. No neurologic deficit was found postoperatively. It is suggested that this simple technique protected the brain for a long period of cerebral circulatory arrest during the aortic arch operation by supplying it with oxygen and simplifying the operative procedure. (J 'fHORAC CARDIOVASC SURG 1992;104:1106-9)
Shinichi Takamoto, MD, Takaaki Matsuda, MD, Mikio Harada, MD, Shigeru Miyata, MD, and Yukio Shimamura, MD, Tokyo, Japan
Hypothermic circulatory arrest is a simple and useful adjunct for aortic arch replacement. However, its shortcoming is that the duration of arrest of the cerebral circulation is limited. The limit of the arrest time is generally thought to be 60 minutes at 15° C.I However, the time required for total aortic arch replacement or for the complex surgery of aortic arch dissection may well exceed that limit. In 1988 Ueda and co-workers/ reported the retrograde perfusion of the brain during aortic arch replacement with a rather laborious procedure for the extracorporeal circulation, in which the superior vena cava alone was perfused compulsorily. We recently found that hypothermic cerebral retrograde perfusion can be achieved by simply From Showa General Hospital, Division of Cardiovascular Surgery, Kodaira, Tokyo, Japan. Received for publication April 30, 1991. Accepted for publication Dec. 3,1991. Address for reprints: Shinichi Takamoto, MD, Showa General Hospital, Divisionof Cardiovascular Surgery 2-450, Tenjin-cho, Kodaira, Tokyo, 187 Japan.
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elevating the central venous pressure in Trendelenburg's position when the aortic arch is open. During profound hypothermic perfusion of the lower half of the body with an occlusion balloon in the descending aorta, venous blood with a high oxygen level supplied the brain tissue with oxygen, protecting it during a long period of cerebral circula tory arrest. Use of this method eliminates the need for taping and clamping the aortic arch and the arch vessels. We carried out two aortic arch replacements with this simple new method, which afforded periods of cerebral circulatory arrest as long as 81 and 65 minutes. This is the preliminary report on this simple hypothermic retrograde cerebral perfusion technique.
Case reports CASE I (Fig. 1). A 53-year-old woman with a dissecting aortic aneurysm (DeBakey type II) and a true aortic arch aneurysm underwent total aortic arch replacement. Surgery was performed through a median sternotomy. The right atrium was cannulated with a single cannula for drainage, and the right femoral artery was also cannulated. The patient was cooledwith a regular cardiopulmonary bypass until the rectal temperature reached 150 C. The ascending aorta was clamped and crystalloid potassium cardioplegia solution was infused into the aortic
Volume 104 Number 4 October 1992
Hypothermic retrograde cerebral perfusion 1 1 07
3
2
1
4
5
/' CPS Flow lLimin/m 2 CVP 15mmHg
Fig. 1. Diagram of total aortic arch replacement with simple hypothermic retrograde cerebral perfusion as in case I. CPB, Cardiopulmonary bypass; CVP, central venous pressure; L V, left ventricular. root. An occlusion balloon was inserted through the left femoral artery into the descending aorta. The position of the balloon in the descending aorta was ascertained by intraoperative echocardiographic scanning.' After the patient had been placed in a mild Trendelenburg's position, the zero level of the transducer of the pressure monitor was adjusted and the central venous pressure was raised to 15 mm Hg, slightly occluding the venous line of the pump. The flow of the cardiopulmonary bypass was then reduced to 1500 ml/rnin, I L/min/m2. When a longitudinal incision was made in the aortic arch without clamping the arch vessels, dark blood, low in oxygen, flowed from the arch vessels into the aortic arch. The flow rate of this blood, which was easily sucked out, was estimated to be about 50 to 100 ml/min in both the innominate artery and the left carotid artery. After the distal anastomosis and the anastomosis with the arch vessels were complete, the occlusion balloon was deflated. The graft was then clamped proximal to these anastomoses, the flowin the cardiopulmonary bypass was raised to the normal flow rate, and rewarming was initiated. Hypothermic retrograde cerebral perfusion was then terminated, and the proximal anastomosis was made during rewarming. The remainder of the operation was completed in the usual manner. Operation time was 430 minutes, cardiopulmonary bypass time 220 minutes, cardiac arrest time 109 minutes, and cerebral circulatory arrest time 81 minutes. CASE 2 (Fig. 2). In a 53-year-old man with acute aortic dissection of DeBakey type I, emergency replacement of the ascending to the proximal arch of the aorta was performed. An emergency transesophageal echo Doppler examination was performed in the intensive care unit, revealing a type I dissection, but the entry was not visualized at the upper ascending aorta because it was in the blind area for this technique."
Although only ascending aortic replacement was planned, an emergency operation was performed through a median sternotomy as follows. Intraoperative echo Doppler examination by direct scanning with a sterile transducer-' revealed the entry in the aortic arch at the root of the brachiocephalic artery. It thus became clear that the proximal aortic arch needed to be replaced. A cardiopulmonary bypass was initiated in the same manner as in case I. During coolingto 15 0 C the ascending aorta was clamped and a crystalloid cardioplegia solution was infused at the aortic root, and the proximal anastomosis at the aortic root was then performed. After the patient was placed in Trendelenburg's position with elevation of the central venous pressure to 15 mm Hg, the cardiopulmonary bypass flow was reduced to 1500ml/min, I L/min/m 2 . The aortic incision was extended to the proximal aortic arch, an occlusion balloon was inserted through the aortic arch into the descending aorta, and retrograde cerebral perfusion was begun. During this retrograde cerebral perfusion a catheter was introduced deeply into the left carotid artery and blood samples were taken through it. Distal anastomosis with the proximal aortic arch was performed, but before this was complete the occlusion balloon was deflated and removed. The cardiopulmonary bypass flow rate was raised to the normal range, and the rewarming was initiated. At this time hypothermic retrograde cerebral perfusion was terminated and cerebral and coronary reperfusion was commenced. The remainder of the operation was completed in the usual manner. The operation time was 420 minutes, cardiopulmonary bypass time 208 minutes, cardiac arrest time 114 minutes, and cerebral circulatory arrest time 65 minutes. Data about the blood used for retrograde cerebral perfusion are presented in Table I. In the venous blood entering the cardiopulmonary bypass mean oxygen pressure was 123 mm Hg,
1 108
The Journal of Thoracic and Cardiovascular
Takamoto et al.
Surgery
4
3
2
Occlusion Balloon
Cardioplegia
It
J' CPB Flow 1L (min 1m' CVP 15mmHg
Cooling-15 C
Fig. 2. Diagram of replacement of ascendingaorta and proximal arch with simple hypothermic retrograde cerebral perfusionas used in case 2. CPR, Cardiopulmonarybypass; CVP, central venous pressure; LV, left ventricular. Table I. Cerebral retrograde perfusion data (case 2) Right atrium blood Time* (min) 23 35 48
Mean
P02
(mmHg)
Carotid artery blood
S02 (%)
Lactate (mg/dl)
98.8 97.8 98.1 98.2
27.8 30.6 30.4 29.6
136 112 121 128
P02
(mm Hg) 32 34 36 34
S02 (%)
Lactate imgfdl]
46.5 50.4 53.3 50.1
29.2 31.2 31.8 30.7
Po-, Oxygen pressure. "Time from start of cerebral retrograde perfusion.
mean oxygen saturation (S02) 98.2%, and mean lactate level 29.6 mgjdl. The retrograde perfusion blood emerging into the carotid artery had a mean oxygen pressure of 34 mm Hg, a mean S02 of 50.1%, and a mean lactate levelof 30.7 mgjdl. The postoperative course of both patients was uneventful. In neither casewere there any signsof neurologic complications or deficits. Also, postoperative computed tomography showed no signs of cerebral infarction, and electroencephalography revealed nothing abnormal in either patient.
Discussion The usefulness of profound hypothermia and circulatory arrest as adjuncts for cerebral protection during aortic arch surgery is limited by the restriction on the duration of cerebral circulatory arrest. This duration is usually considered to be 60 minutes at 15° C.' RecentlyUeda and co-workersv ' reported clinical cases of retrograde cerebral perfusion through the superior vena cava under oth-
erwise total circulatory arrest. Their methods, however, necessitated a rather cumbersome procedure with the bypass pump, and they did not claim any extension of cerebral circulatory arrest time. In our method, when the blood perfusing the lower half of the body under profound hypothermia returned to the right atrium, it had a high oxygen level (>95% of S02) because of the very low oxygen consumption. The high central venous pressure (15 mm Hg) in Trendelenburg's position with the aortic arch open caused the oxygen-rich venous blood to perfuse the brain tissue from the right atrium through the jugular vein, and emerge from the carotid artery. During this simple retrograde cerebral perfusion, oxygen consumption took place in the brain tissue even in profound hypothermia, and the blood emerging through the carotid artery was dark. In case 2 a small amount of lactate was produced during the retro-
Volume 104 Number 4 October 1992
grade perfusion. Because hypothermic cardiopulmonary bypass itself produces lactate for several reasons.v? the small amounts of lactate produced and significant oxygen extraction in the brain suggested that aerobic metabolism might be proceeding at least in some parts of the brain tissue. The brain tissue was thus protected during long cerebral circulatory arrest periods of 81 and 65 minutes at 15° C. The uneventful postoperative courses of these cases suggested that the cerebral circulatory arrest time might be extended to more than 90 minutes. This method, which avoids clamping of the aortic arch and the arch vessels, has been employed by others 8- 10 to prevent cerebral embolization from a dissected or atheromatous aorta, or from dissected or atheromatous arch vessels, but not for oxygen distribution to the brain tissue by retrograde perfusion, as was done in our cases. The new method is simple and requires neither special preoperative preparation, special equipment, bypass circuits, or extra dissection even when the operative procedure is altered intraoperatively as in case 2. Accordingly, the new method is suitable not only for elective surgery but also for emergency surgery. Especially with the aid of transesophageal and intraoperative echo studies.l-" it should increase the safety of high- risk emergency surgery. We are grateful to Mr. Chris W. Reynolds for English-language correction of this manuscript. REFERENCES I. Griepp RB, Stinson EB, Hollingsworth JF, Buehler D. Prosthetic replacement of the aortic arch. J THORAC CARDIOVASC SURG 1975;70;1051-63. 2. Veda V, Mild S, Kusuhara K, et al. Surgical treatment of
Hypothermic retrograde cerebral perfusion
1 109
the aneurysm or dissection involving ascending aorta and aortic arch utilizing circulatory arrest and retrograde perfusion. J Jpn Assoc Thor Surg 1988;36;161-6. 3. Takamoto S, Kyo S, Adachi H, Matsumura M, Yokote Y, Omoto R. Intraoperative color flow mapping by real-time two-dimensional Doppler echocardiography for evaluation of valvular and congenital heart disease and vascular disease. J THoRAc CARDIOVASC SURG 1985;90:802-12. 4. Takamoto S, Omoto R. Visualizationof thoracic dissecting aortic aneurysm by transesophageal Doppler color flow mapping. Herz 1987;12;187-93. 5. Veda Y, Mild S, Kusuhara K, Okita Y, Tahata T, Yamanaka K. Surgical treatment of aneurysm or dissection involving the ascending aorta and aortic arch, utilizing circulatory arrest and retrograde cerebral perfusion. J CardiovascSurg 1990;31 :553-8. 6. Huckabee WE. Relationship of pyruvate and lactate during anaerobic metabolism. I. Effectsof infusionof pyruvate or glucoseand hyperventilation.J Clin Invest 1958;37:24454. 7. Ballinger WF II, Vollenweider H, Pierucci L Jr, Templeton JV III. Anaerobic metabolism and metabolic acidosis during cardiopulmonary bypass. Ann Surg 1961;153:499506. 8. Mahfood S, Qazi A, Garcia J, Mispireta L, Corso P, Smyth N. Management of aortic arch aneurysm using hypothermia and circulatory arrest. Ann Thorac Surg 1985;39: 412-7. 9. Crawford ES, CoselliJS, Safi HJ. Partial cardiopulmonary bypass, hypothermic circulatory arrest, and posterolateral exposurefor thoracic aortic aneurysm operation. J THORAC CARDIOVASC SURG 1987;94:824-7. 10. Sheld HH, Gorlach G, Russ W, Netle H, Loslot F, Hehrlein FW. Aortic arch replacement by posterolateral exposure. Thorac Cardiovasc Surg 1988;36;100-4.
Shinichi Takamoto, MD, Takaaki Matsuda, MD, Mikio Harada, MD, Shigeru Miyata, MD, and Yukio Shimamura, MD, Tokyo, Japan
Hypothermic circulatory arrest is a simple and useful adjunct for aortic arch replacement. However, its shortcoming is that the duration of arrest of the cerebral circulation is limited. The limit of the arrest time is generally thought to be 60 minutes at 15° C.I However, the time required for total aortic arch replacement or for the complex surgery of aortic arch dissection may well exceed that limit. In 1988 Ueda and co-workers/ reported the retrograde perfusion of the brain during aortic arch replacement with a rather laborious procedure for the extracorporeal circulation, in which the superior vena cava alone was perfused compulsorily. We recently found that hypothermic cerebral retrograde perfusion can be achieved by simply From Showa General Hospital, Division of Cardiovascular Surgery, Kodaira, Tokyo, Japan. Received for publication April 30, 1991. Accepted for publication Dec. 3,1991. Address for reprints: Shinichi Takamoto, MD, Showa General Hospital, Divisionof Cardiovascular Surgery 2-450, Tenjin-cho, Kodaira, Tokyo, 187 Japan.
12/1/35714
1 106
elevating the central venous pressure in Trendelenburg's position when the aortic arch is open. During profound hypothermic perfusion of the lower half of the body with an occlusion balloon in the descending aorta, venous blood with a high oxygen level supplied the brain tissue with oxygen, protecting it during a long period of cerebral circula tory arrest. Use of this method eliminates the need for taping and clamping the aortic arch and the arch vessels. We carried out two aortic arch replacements with this simple new method, which afforded periods of cerebral circulatory arrest as long as 81 and 65 minutes. This is the preliminary report on this simple hypothermic retrograde cerebral perfusion technique.
Case reports CASE I (Fig. 1). A 53-year-old woman with a dissecting aortic aneurysm (DeBakey type II) and a true aortic arch aneurysm underwent total aortic arch replacement. Surgery was performed through a median sternotomy. The right atrium was cannulated with a single cannula for drainage, and the right femoral artery was also cannulated. The patient was cooledwith a regular cardiopulmonary bypass until the rectal temperature reached 150 C. The ascending aorta was clamped and crystalloid potassium cardioplegia solution was infused into the aortic
Volume 104 Number 4 October 1992
Hypothermic retrograde cerebral perfusion 1 1 07
3
2
1
4
5
/' CPS Flow lLimin/m 2 CVP 15mmHg
Fig. 1. Diagram of total aortic arch replacement with simple hypothermic retrograde cerebral perfusion as in case I. CPB, Cardiopulmonary bypass; CVP, central venous pressure; L V, left ventricular. root. An occlusion balloon was inserted through the left femoral artery into the descending aorta. The position of the balloon in the descending aorta was ascertained by intraoperative echocardiographic scanning.' After the patient had been placed in a mild Trendelenburg's position, the zero level of the transducer of the pressure monitor was adjusted and the central venous pressure was raised to 15 mm Hg, slightly occluding the venous line of the pump. The flow of the cardiopulmonary bypass was then reduced to 1500 ml/rnin, I L/min/m2. When a longitudinal incision was made in the aortic arch without clamping the arch vessels, dark blood, low in oxygen, flowed from the arch vessels into the aortic arch. The flow rate of this blood, which was easily sucked out, was estimated to be about 50 to 100 ml/min in both the innominate artery and the left carotid artery. After the distal anastomosis and the anastomosis with the arch vessels were complete, the occlusion balloon was deflated. The graft was then clamped proximal to these anastomoses, the flowin the cardiopulmonary bypass was raised to the normal flow rate, and rewarming was initiated. Hypothermic retrograde cerebral perfusion was then terminated, and the proximal anastomosis was made during rewarming. The remainder of the operation was completed in the usual manner. Operation time was 430 minutes, cardiopulmonary bypass time 220 minutes, cardiac arrest time 109 minutes, and cerebral circulatory arrest time 81 minutes. CASE 2 (Fig. 2). In a 53-year-old man with acute aortic dissection of DeBakey type I, emergency replacement of the ascending to the proximal arch of the aorta was performed. An emergency transesophageal echo Doppler examination was performed in the intensive care unit, revealing a type I dissection, but the entry was not visualized at the upper ascending aorta because it was in the blind area for this technique."
Although only ascending aortic replacement was planned, an emergency operation was performed through a median sternotomy as follows. Intraoperative echo Doppler examination by direct scanning with a sterile transducer-' revealed the entry in the aortic arch at the root of the brachiocephalic artery. It thus became clear that the proximal aortic arch needed to be replaced. A cardiopulmonary bypass was initiated in the same manner as in case I. During coolingto 15 0 C the ascending aorta was clamped and a crystalloid cardioplegia solution was infused at the aortic root, and the proximal anastomosis at the aortic root was then performed. After the patient was placed in Trendelenburg's position with elevation of the central venous pressure to 15 mm Hg, the cardiopulmonary bypass flow was reduced to 1500ml/min, I L/min/m 2 . The aortic incision was extended to the proximal aortic arch, an occlusion balloon was inserted through the aortic arch into the descending aorta, and retrograde cerebral perfusion was begun. During this retrograde cerebral perfusion a catheter was introduced deeply into the left carotid artery and blood samples were taken through it. Distal anastomosis with the proximal aortic arch was performed, but before this was complete the occlusion balloon was deflated and removed. The cardiopulmonary bypass flow rate was raised to the normal range, and the rewarming was initiated. At this time hypothermic retrograde cerebral perfusion was terminated and cerebral and coronary reperfusion was commenced. The remainder of the operation was completed in the usual manner. The operation time was 420 minutes, cardiopulmonary bypass time 208 minutes, cardiac arrest time 114 minutes, and cerebral circulatory arrest time 65 minutes. Data about the blood used for retrograde cerebral perfusion are presented in Table I. In the venous blood entering the cardiopulmonary bypass mean oxygen pressure was 123 mm Hg,
1 108
The Journal of Thoracic and Cardiovascular
Takamoto et al.
Surgery
4
3
2
Occlusion Balloon
Cardioplegia
It
J' CPB Flow 1L (min 1m' CVP 15mmHg
Cooling-15 C
Fig. 2. Diagram of replacement of ascendingaorta and proximal arch with simple hypothermic retrograde cerebral perfusionas used in case 2. CPR, Cardiopulmonarybypass; CVP, central venous pressure; LV, left ventricular. Table I. Cerebral retrograde perfusion data (case 2) Right atrium blood Time* (min) 23 35 48
Mean
P02
(mmHg)
Carotid artery blood
S02 (%)
Lactate (mg/dl)
98.8 97.8 98.1 98.2
27.8 30.6 30.4 29.6
136 112 121 128
P02
(mm Hg) 32 34 36 34
S02 (%)
Lactate imgfdl]
46.5 50.4 53.3 50.1
29.2 31.2 31.8 30.7
Po-, Oxygen pressure. "Time from start of cerebral retrograde perfusion.
mean oxygen saturation (S02) 98.2%, and mean lactate level 29.6 mgjdl. The retrograde perfusion blood emerging into the carotid artery had a mean oxygen pressure of 34 mm Hg, a mean S02 of 50.1%, and a mean lactate levelof 30.7 mgjdl. The postoperative course of both patients was uneventful. In neither casewere there any signsof neurologic complications or deficits. Also, postoperative computed tomography showed no signs of cerebral infarction, and electroencephalography revealed nothing abnormal in either patient.
Discussion The usefulness of profound hypothermia and circulatory arrest as adjuncts for cerebral protection during aortic arch surgery is limited by the restriction on the duration of cerebral circulatory arrest. This duration is usually considered to be 60 minutes at 15° C.' RecentlyUeda and co-workersv ' reported clinical cases of retrograde cerebral perfusion through the superior vena cava under oth-
erwise total circulatory arrest. Their methods, however, necessitated a rather cumbersome procedure with the bypass pump, and they did not claim any extension of cerebral circulatory arrest time. In our method, when the blood perfusing the lower half of the body under profound hypothermia returned to the right atrium, it had a high oxygen level (>95% of S02) because of the very low oxygen consumption. The high central venous pressure (15 mm Hg) in Trendelenburg's position with the aortic arch open caused the oxygen-rich venous blood to perfuse the brain tissue from the right atrium through the jugular vein, and emerge from the carotid artery. During this simple retrograde cerebral perfusion, oxygen consumption took place in the brain tissue even in profound hypothermia, and the blood emerging through the carotid artery was dark. In case 2 a small amount of lactate was produced during the retro-
Volume 104 Number 4 October 1992
grade perfusion. Because hypothermic cardiopulmonary bypass itself produces lactate for several reasons.v? the small amounts of lactate produced and significant oxygen extraction in the brain suggested that aerobic metabolism might be proceeding at least in some parts of the brain tissue. The brain tissue was thus protected during long cerebral circulatory arrest periods of 81 and 65 minutes at 15° C. The uneventful postoperative courses of these cases suggested that the cerebral circulatory arrest time might be extended to more than 90 minutes. This method, which avoids clamping of the aortic arch and the arch vessels, has been employed by others 8- 10 to prevent cerebral embolization from a dissected or atheromatous aorta, or from dissected or atheromatous arch vessels, but not for oxygen distribution to the brain tissue by retrograde perfusion, as was done in our cases. The new method is simple and requires neither special preoperative preparation, special equipment, bypass circuits, or extra dissection even when the operative procedure is altered intraoperatively as in case 2. Accordingly, the new method is suitable not only for elective surgery but also for emergency surgery. Especially with the aid of transesophageal and intraoperative echo studies.l-" it should increase the safety of high- risk emergency surgery. We are grateful to Mr. Chris W. Reynolds for English-language correction of this manuscript. REFERENCES I. Griepp RB, Stinson EB, Hollingsworth JF, Buehler D. Prosthetic replacement of the aortic arch. J THORAC CARDIOVASC SURG 1975;70;1051-63. 2. Veda V, Mild S, Kusuhara K, et al. Surgical treatment of
Hypothermic retrograde cerebral perfusion
1 109
the aneurysm or dissection involving ascending aorta and aortic arch utilizing circulatory arrest and retrograde perfusion. J Jpn Assoc Thor Surg 1988;36;161-6. 3. Takamoto S, Kyo S, Adachi H, Matsumura M, Yokote Y, Omoto R. Intraoperative color flow mapping by real-time two-dimensional Doppler echocardiography for evaluation of valvular and congenital heart disease and vascular disease. J THoRAc CARDIOVASC SURG 1985;90:802-12. 4. Takamoto S, Omoto R. Visualizationof thoracic dissecting aortic aneurysm by transesophageal Doppler color flow mapping. Herz 1987;12;187-93. 5. Veda Y, Mild S, Kusuhara K, Okita Y, Tahata T, Yamanaka K. Surgical treatment of aneurysm or dissection involving the ascending aorta and aortic arch, utilizing circulatory arrest and retrograde cerebral perfusion. J CardiovascSurg 1990;31 :553-8. 6. Huckabee WE. Relationship of pyruvate and lactate during anaerobic metabolism. I. Effectsof infusionof pyruvate or glucoseand hyperventilation.J Clin Invest 1958;37:24454. 7. Ballinger WF II, Vollenweider H, Pierucci L Jr, Templeton JV III. Anaerobic metabolism and metabolic acidosis during cardiopulmonary bypass. Ann Surg 1961;153:499506. 8. Mahfood S, Qazi A, Garcia J, Mispireta L, Corso P, Smyth N. Management of aortic arch aneurysm using hypothermia and circulatory arrest. Ann Thorac Surg 1985;39: 412-7. 9. Crawford ES, CoselliJS, Safi HJ. Partial cardiopulmonary bypass, hypothermic circulatory arrest, and posterolateral exposurefor thoracic aortic aneurysm operation. J THORAC CARDIOVASC SURG 1987;94:824-7. 10. Sheld HH, Gorlach G, Russ W, Netle H, Loslot F, Hehrlein FW. Aortic arch replacement by posterolateral exposure. Thorac Cardiovasc Surg 1988;36;100-4.