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* From the Department of Surgery, University of California at Los Angeles Medical Center, Los Angeles, CA.
Correspondence to: Fardad Esmailian, MD, FCCP, UCLA School of Medicine, Division of Cardiothoracic Surgery, 10833 LeConte Ave, 62–266 CHS, Los Angeles, CA 90095-1741; e-mail: fesmaili{at}surgery.medsch.ucla.edu
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Abstract |
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Design: Retrospective chart review of 52 cardiac surgery patients (34 male and 18 female; age range, 3 weeks to 89 years old; mean age, 60 years old) who received RCP in conjunction with DHCA from July 1991 through August 1998.
Results: Surgical procedures consisted of the following: (1) repair of ascending aortic aneurysms (n = 16); (2) repair of type A aortic dissection (n = 16); (3) repair of arch aneurysms (n = 10); (4) renal cell carcinoma with tumor extension to the inferior vena cava (IVC) and right atrium (n = 5); (6) coronary artery bypass grafting and concomitant aortic valve replacement with calcified aorta (n = 2); (7) Norwood procedure and take down of a Pott's shunt (n = 2); and (8) massive air embolism treatment (n = 1). Mean RCP time was 39 min (range, 3 to 88 min). Thirteen patients had RCP times > 60 min. Mean core temperature (rectal or bladder) was 19°C (range, 15° to 28°C). There were six early deaths, four of which were related to persistent low-output cardiac failure, and two resulted from perioperative stroke. All remaining patients recovered fully without neurologic deficits.
Conclusion: RCP is a reliable and technically appealing tool that does the following: (1) it improves DHCA safety and is applicable in a variety of clinical settings with relative ease; (2) it potentially provides oxygen and nutritional support to the brain during DHCA; (3) it helps remove air and other debris from the cerebral vessels; and (4) it is useful in dealing with congenital heart disease and tumor extension into the IVC.
Key Words: aortic dissection • circulatory arrest • retrograde cerebral perfusion
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Introduction |
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In 1980, Mills and Ochsner5 reported the use of retrograde cerebral perfusion (RCP) via the superior vena cava (SVC) to treat massive air embolism and provide brain protection. It was not until 1986 that Ueda and associates6 developed a clinically feasible method for the application of RCP to be used concurrently with DHCA to improve cerebral protection. Several recent studies7 8 using neurophysiologic monitoring have shown that the blood flow and oxygen delivered by means of RCP reaches the brain. We report our experience using RCP in conjunction with DHCA to repair complex congenital and adult cardiac cases.
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Materials and Methods |
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In cases of acute aortic dissection, ascending aortic aneurysms, selective redo cases, and calcified ascending aorta, a median sternotomy incision is made and, at the same time, the femoral vessels are exposed. Heparin, 3 mg/kg, is administered, and the femoral artery or distal aorta is cannulated. The SVC and inferior vena cava (IVC) are directly cannulated; however, in acute dissection and selective redo cases, the femoral vein is cannulated initially. A retrograde cardioplegia catheter is placed into the coronary sinus via the right atrium.
Methylprednisolone, 30 mg/kg, and mannitol, 0.5 mg/kg, are added to the pump prime for potential reduction in cerebral edema. Serum glucose is maintained close to 200 mg/dL during the entire procedure. The patient is placed on cardiopulmonary bypass (CPB) and slowly cooled to 20°C. Full flow is continued until the desired temperature is reached. A left ventricular vent is placed through the right superior pulmonary vein. The aorta is cross-clamped after the heart starts fibrillating, and retrograde cold blood high potassium cardioplegia is administered to arrest the heart. Concurrently, in cases of aortic aneurysm or dissection, the aorta is opened and direct antegrade cardioplegia is delivered into the coronary ostia.
Throughout the procedure, myocardial protection is achieved with retrograde cold blood cardioplegia given at 10 to 15 min intervals and with antegrade cold blood cardioplegia delivered into the coronary ostia every 20 to 30 min. Patients with coronary artery disease who require bypass grafting are given additional cardioplegia down each graft after the completion of each distal anastomosis. An insulating pad is placed around the heart to protect the phrenic nerve, and enough ice slush is used to cover the right ventricle for topical hypothermia. The patient is further cooled down to 15°C; when the bladder temperature reaches 18°C, the pump is turned off, the cross-clamp is removed, and the patient is drained.
RCP is then started by directing the flow of the arterial limb of the perfusion circuit to the snared SVC cannula. The flow is maintained at about one-third systemic to achieve a pressure not > 25 to 30 mm Hg, measured via a right internal jugular line placed percutaneously at the beginning of the procedure. A collagen-impregnated Dacron graft is used to repair aortic aneurysms or dissections. The distal anastomosis is performed using running 3–0 polypropylene suture reinforced with a pericardial strip. The patient is then placed in the Trendelenberg position, air and debris are evacuated from the graft, RCP is discontinued, flow is slowly restarted through the arterial cannula, and the graft is back flushed. CPB is reinstituted, and the cross-clamp is reapplied to the graft. Rewarming is started while the aortic root portion of the procedure is completed.
The aortic cross-clamp is removed following de-airing of the heart, and the patient is then weaned off CPB.
In patients with renal cell carcinoma extending into the IVC and right atrium (RA), the femoral vein is cannulated in addition to the SVC. CPB is established, and the patient is cooled down. DHCA and RCP are then used to remove the tumor from the intrapericardial IVC and RA under direct vision. If the tumor is adherent to these structures, the mass is resected en bloc. Autologous pericardium is then used to reconstruct the IVC and RA.
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Results |
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Among the 15 patients who received RCP/DHCA for > 45 min, 12 had no neurologic deficit and 2 had a major cerebral vascular accident (CVA) resulting in death. Another patient had a subdural hematoma, and one developed a temporary decrease in mental status with no permanent sequelae or abnormality in the head CT scan. Both patients who developed a stroke received RCP/DHCA for > 70 min (Table 3 ).
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The second in-hospital death occurred in a 77-year-old woman with a history of renal insufficiency and COPD, in whom the repair of an aortic arch aneurysm with a Dacron and concomitant AVR/CABG was performed with a RCP time of 1 h. This patient also developed persistent low cardiac output that was unresponsive to inotropes and intraaortic balloon counterpulsation, and multiorgan failure. She died on the 16th postoperative day. A neurologic evaluation showed that her altered mental status was probably due to metabolic factors and not a result of intraoperative ischemia.
A 67-year-old woman, the third death in the series, required emergent repair of a type A aortic dissection with intrapericardial rupture and tamponade. The RCP time was 29 min. She developed severe postoperative coagulopathy and never regained cardiovascular stability. She died on the first postoperative day.
The fourth death occurred in a 69-year-old man who underwent repair of an aortic arch aneurysm and CABG with an RCP time of 88 min. The patient failed to awaken after surgery. A neurologic evaluation and a head CT scan revealed multiple areas of infarct consistent with an embolic source. He showed no signs of neurologic improvement and was declared brain dead on the 10th postoperative day.
A 71-year-old woman underwent repair of a ruptured ascending aortic aneurysm. The RCP time was 73 min. She returned to the operating room for mediastinal bleeding in the early postoperative period, but developed poor ventricular function and ECG changes consistent with perioperative myocardial infarction following her reexploration. On the second postoperative day, she deteriorated neurologically and a massive stroke was diagnosed. She died later that day, the fifth death in our series.
A 35-year-old man admitted with an acute type-A aortic dissection that extended to the femoral vessels and ruptured into the left hemithorax was the sixth death in our series. He required reconstruction of the ascending, transverse, and descending aortas. The duration of RCP was 86 min, and he died in the operating room due to profound coagulopathy and low cardiac output.
Comments
More than 300,000 cardiac surgical procedures that require the use
of CPB are performed yearly in the United States. Despite advances in
technique and the use of membrane oxygenators, arterial filters, and
air sensing devices, the incidence of neurologic injury in patients
undergoing CPB has increased,9
reportedly as high
as 50 to 70%.10
11
Postoperative deficits range from mild
symptoms and cognitive problems to severe neurologic damage, stroke,
and death. The probability of having a perioperative stroke ranges from
4.8 to 5.2% for patients undergoing CPB12
; however, if a
period of circulatory arrest is required (specifically, > 45 min),
this probability figure reaches 9 to 12%.11
12
Furthermore, circulatory arrest periods extending > 65 min increase
the mortality rate.1
This time limit reflects the fact
that during DHCA, delivery of oxygen to the brain stops but cerebral
metabolism is only reduced.5
Various centers7 have implemented RCP as part of the DHCA protocol in an effort to extend the safe period of circulatory arrest. Safi et al13 recently reported using RCP in 120 of 161 patients who underwent repair of ascending aortic and arch aneurysms. They were able to maintain SVC pressure of 25 mm Hg and a flow of 500 mL/min in the RCP group, which resulted in a decreased stroke rate (3% vs 9%).
It has been difficult to determine exactly how long DHCA can safely be extended by applying RCP. Sasaguri et al14 presented 20 patients who received RCP/DHCA for a mean of 74 min with no neurologic deficits. Five of the 20 patients received RCP for > 90 min.
We extended RCP successfully beyond aortic surgery to include cases of complex congenital heart problems, renal cell carcinoma extending to the IVC, massive air embolism, and severely calcified aortas in patients requiring AVR or combined AVR/CABG. The overall stroke rate and stroke-related mortality rate in the current study was 4% (2 of 52 patients).
In conclusion, RCP proved to be an extremely useful treatment modality when applied concurrently with DHCA. This technique lowered the incidence of major neurologic events, especially among patients requiring > 45 min of circulatory arrest. It is possible that the beneficial effects were achieved through several mechanisms, including delivery of oxygen and metabolic substrates to the brain during DHCA, clearance of toxic metabolic waste products, prevention of reperfusion injury to the brain, and flushing of air and debris from the cerebral circulation.
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Footnotes |
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Received for publication October 29, 1998. Accepted for publication May 12, 1999.
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