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Outcome of abdominal aortic aneurysm repair in patients with previous spinal cord injury in the Department of Veterans' Affairs hospitals
PII: S0967-2109(97)00027-6
Cardiovascular Surgery, Vol. 5, No. 3, pp. 286–290, 1997 1997 The International Society for Cardiovascular Surgery Published by Elsevier Science Ltd. Printed in Great Britain 0967–2109/97 $17.00 + 0.00
Outcome of abdominal aortic aneurysm repair in patients with previous spinal cord injury in the Department of Veterans’ Affairs hospitals D. L. Jacobs, W. E. Longo, G. J. Peterson, L. W. McKirgan, K. S. Virgo and F. E. Johnson Department of Surgery, St Louis University School of Medicine and Surgery Service, John Cochran VA Medical Center, St. Louis, Missouri, USA A retrospective review was carried out to determine the morbidity and mortality of abdominal aortic aneurysm repair in patients with previous spinal cord injury. A population-based study utilizing computer records on all patients in Department of Veterans’ Affairs medical centers from 1987–1991 identified 31 patients with spinal cord injury who underwent subsequent infrarenal abdominal aortic aneurysm repair. Additional information was obtained from individual medical records. Some twenty patients (65%) were paraplegics and 11 (35%) were quadriplegics. Aneurysms were most commonly discovered incidentally during work-up of other conditions. All patients had no symptoms referable to their abdominal aortic aneurysm. In total, 29 patients (94%) underwent elective operations. The complication rate (57%) involved mostly pulmonary, cutaneous or urinary tract morbidity. The 30-day mortality rate was 3% for elective abdominal aortic aneurysm repair. Two patients were operated upon as emergencies for rupture, with one operative death. Long-term follow-up revealed a median survival duration of 5.4 years after aneurysm repair. In conclusion, abdominal aortic aneurysm repair in patients with previous spinal cord injury has a low mortality rate. Postoperative complications are often related to spinal cord injury and are potentially preventable; thus, such injury should not preclude surgical intervention for abdominal aortic aneurysm. 1997 The International Society for Cardiovascular Surgery Keywords: abdominal aortic aneurysm, spinal cord injury
Abdominal aortic aneurysms are estimated to be present in 2–5% of the population aged over 60 years, and the incidence is increasing [1]. Though typically symptom-free unless ruptured, pain from pressure or stretching in the retroperitoneum as the abdominal aortic aneurysm expands, resulting in a diagnosis of a symptomatic, non-ruptured aneurysm, is reported to occur in up to 14% of cases [2]. Symptomless aneurysms are often detected incidentally on plain films of the abdomen when calcification of the aortic wall reveals the aneurysm outline (noted in
Correspondence to: Dr D. L. Jacobs, Department of Surgery, St Louis University School of Medicine, 3635 Vista at Grand Blvd., PO Box 15250, St Louis, MO 63110-0250, USA
286
40% of patients with an abdominal aortic aneurysm), or by ultrasound or computed tomography studies of the abdomen. The reported increased incidence of abdominal aortic aneurysm is in part due to the more frequent incidental diagnosis of the problem as these imaging modalities are used more often. Screening protocols using ultrasound have been proposed for the detection of abdominal aortic aneurysm, particularly for high-risk groups such as patients aged over 50 who have hypertension, coronary artery disease, peripheral vascular disease or a family history of abdominal aortic aneurysm [3]. However, screening of the population in general has not been shown to be cost-effective [3]. Patients with motor-sensory deficits due to spinal cord injury are highly predisposed to develop comCARDIOVASCULAR SURGERY
JUNE 1997 VOL 5 NO 3
Abdominal aortic aneurysm repair with spinal cord injury: D. L. Jacobs et al.
plications such as urinary tract infection, pressure sores, and pneumonia. Due to the high incidence of these complications, such patients often have imaging studies of the abdomen and pelvis; this could potentially result in increased incidental diagnosis of an abdominal aortic aneurysm. Sensory deficits in spinal cord injury patients can make the diagnosis of common diseases challenging [4]. They could also prevent perception of pain associated with an abdominal aortic aneurysm, resulting in a delayed diagnosis of an acutely expanding or ruptured aneurysm. The clinical presentation and outcome of patients with previous spinal cord injury who undergo repair of an abdominal aortic aneurysm is known only by anecdotal reports [5]. This study utilized large computer-based data sets to compile a large, contemporary series of patients with these two diagnoses to better define their clinical course and to provide for management guidelines.
Patients and methods The records of the Department of Veterans Affairs (DVA) from calendar years 1987–1991 were reviewed for this study. The computer-based information was accessed through the DVA Data Processing Center in Austin, Texas. The first data set employed was the Beneficiary Identification and Records Location System (BIRLS), which is the primary source of mortality information on veterans and beneficiaries in the DVA. A second source of information was the Patient Treatment Files (PTF), a database which records information about each episode of inpatient and outpatient care provided under VA auspices. Since information about patients cared for this in this system is available in a standard format through a single, accessible computer system, the two data bases were surveyed to gather data on all those patients with the diagnostic codes (ICD-9-CM) for paraplegia (344.0), or quadriplegia (344.1), and abdominal aortic aneurysm (441.4) and abdominal aortic replacement (38.44) [6]. This allowed identification of patients that had pre-existing spinal cord injury and underwent an abdominal aortic aneurysm repair. No data were obtained on patients with spinal cord injury and abdominal aortic aneurysm who were not operated on for their aneurysm. Data from the DVA hospital system for calendar years 1987– 1991 were chosen to insure a contemporary patient population, and permit adequate follow-up to detect as many late complications as possible. Suitable patients were identified from 14 DVA medical centers. To supplement the computerderived data, additional information was sought from these DVA facilities. A customized standard questionnaire was employed requesting demographic CARDIOVASCULAR SURGERY
JUNE 1997 VOL 5 NO 3
data not obtainable from BIRLS or PTF, as well as copies of discharge summaries, operative reports, and pathology reports. Data obtained included age, sex, date of admission, initial diagnosis, diagnostic procedures and results, operative procedures, operative and postoperative complications, length of stay, length of post-treatment survival and cause of death. Although in-hospital mortality information was available from PTF data, that concerning mortality after discharge was not. BIRLS contains records of all veterans whose beneficiaries applied for death benefits at the time of their demise, whether outside the hospital or within the DVA or other hospitals. The date of death is recorded for each veteran in whose name benefits are requested. A recent comparison of mortality recording systems estimated that 80–89% of all veterans’ death are recorded by BIRLS [7]. The BIRLS mortality information agreed with PTF records when both were available, and there is no suggestion that requests for benefits varies significantly across treatment groups [8]. Finally, US Social Security Administration death records were searched for all patients without a BIRLS death record; those without a record of death in any of the three systems were assumed to be alive. Long-term survival data were compiled and median survival determined using life-table analysis.
Results Between 1 January, 1987 and 31 December, 1991, a total of 50 patients were identified from the PTF with ICD-9-CM diagnostic codes for spinal cord injury, abdominal aortic aneurysm, and such aneurysm repair. Data on 31 (62%) spinal cord injury patients who underwent subsequent infrarenal abdominal aortic aneurysm repair were sufficient for the cases to be evaluable. These 31 patients comprise the study population. The mean duration of followup was 4.4 years. Patient demographics The mean age of the 31 patients in this study was 62 (range 52–71) years; all were males. The mean duration of neurologic deficit prior to surgery was 20 years. Twenty of the patients (65%) were paraplegics; the remaining 11 (35%) were quadriplegics. Two patients had previously had thoracoabdominal aortic aneurysm repairs resulting in postoperative paralysis and subsequently required abdominal aortic aneurysm repair. Symptoms and evaluation At the time of abdominal aortic aneurysm diagnosis, patients often had symptoms related to the urinary tract or pelvic skeleton. None of the 31 patients had symptoms judged by their physicians to be suggestive 287
Abdominal aortic aneurysm repair with spinal cord injury: D. L. Jacobs et al.
of abdominal aortic aneurysm. This was even the case in one patient with a leaking abdominal aortic aneurysm who presented hemodynamically unstable and was thought to have urosepsis. This patient subsequently had the diagnosis of contained rupture of an abdominal aortic aneurysm made several days after admission. Twelve patients (35%) had the aneurysm discovered on physical examination, typically at the time of an annual examination in a spinal cord injury clinic. Aneurysms were also discovered incidentally by abdominal ultrasound (10), pelvic X-ray (five) and abdominal computed tomography scan. One patient presented initially with a femoral pseudoaneurysm and had rupture of an unsuspected abdominal aortic aneurysm while undergoing repair of the femoral aneurysm. The initial diagnoses at the time of presentation are depicted in Table 1. The mean aneurysm size was 6.1 (range 4.5–11) cm. Twenty-five patients (81%) underwent computed tomography scan; 20 (65%) underwent arteriography to delineate the extent of the abdominal aortic aneurysm and any associated arterial occlusive disease. Treatment and outcome Twenty-nine patients (94%) underwent elective operation; two were operated on as emergencies for rupture. Twenty one (68%) repairs were tube grafts and the remaining 10 were bifurcated grafts. One patient died of a myocardial infarction 3 weeks after elective abdominal aortic aneurysm repair, yielding a 30-day mortality rate for this situation of 3%. Of the two patients operated on as emergencies, one died from loss of blood. Operative management of these patients did not reveal difficulties with unusual declamping hypotension due to decreased vasomotor tone in the denervated lower extremities. Utilization of vasopressor drugs in the perioperative period was common, but dosages and duration of use was not well docu-
mented. The methods of deep venous thrombosis prophylaxis used were not able to be determined; however, none of the patients had documentation of a postoperative deep venous thrombosis or pulmonary embolism. A complication rate of 57% was observed and involved mostly infectious pulmonary, cutaneous or urinary tract morbidity which was related to complications of spinal cord injury present before abdominal aortic aneurysm repair. One patient required an above-knee amputation in the early postoperative period due to a pre-existing decubitus ulcer which precluded limb salvage. One patient developed renal failure secondary to acute tubular necrosis but had complete recovery of renal function after 6 weeks. Two patients developed acute postoperative graft thrombosis: one required revision of a tube graft to an aortobifemoral graft, and a second required thrombectomy of an aortobifemoral graft. The overall mean hospital stay was 43 (range 7–210) days. Extended length of stay was related to the high incidence of postoperative complications noted above. Long-term follow-up revealed a median survival of 5.4 years. The survival curve is depicted in Figure 1. One patient developed a late graft infection 4 years postoperatively.
Discussion The rising sophistication of computer-based data sets, the ever-increasing depth of available data, and the current level of skill in extracting data from such resources, enhances the ability to obtain information on meaningfully large populations of patients with unusual constellations of diagnoses of interest. In the present study there was heavy reliance on computer searches of very large data sets to identify the patient
Table 1 Initial diagnoses* in spinal cord injury patients at the time of incidental diagnosis of an abdominal aortic aneurysm Initial diagnosis
No. of patients
Nephrolithiasis Trauma/fracture Cholecystitis Urosepsis Abdominal malignancy Arterial occlusive disease Rectal prolapse Femoral artery pseudoaneurysm
10 (32) 4 (13) 3 (10) 2 (6) 2 (6) 1 (3) 1 (3) 1 (3)
*Seven patients (23%) had their abdominal aortic aneurysm discovered at the time of a health maintenance examination in a spinal cord injury clinic and had no other diagnoses noted at that time. Values in parentheses are percentages.
288
Figure 1 Life-table survival curve after abdominal aortic aneurysm repair in patients with previous spinal cord injury
CARDIOVASCULAR SURGERY
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Abdominal aortic aneurysm repair with spinal cord injury: D. L. Jacobs et al.
population and to provide basic clinical, demographic and survival information. The information available in these datasets was supplemented with additional clinical data from the clinical records, in order to maximize the accuracy of the information presented. The diagnosis of abdominal aortic aneurysm in spinal cord injury patients was most often made incidentally during imaging studies performed to evaluate pathologies related to their neurologic injury. The most common initial diagnosis was nephrolithiasis, (32.7%) (Table 1). Routine ultrasound on an annual basis to screen for nephrolithiasis was the most common reason for obtaining the imaging study that resulted in the diagnosis of abdominal aortic aneurysm. The relatively frequent evaluation of these patients by such surveillance appears to have resulted in the diagnosis of abdominal aortic aneurysms that otherwise would have gone undetected. Approximately one-third of patients had their abdominal aortic aneurysm diagnosed on physical examination, the majority of which were performed as part of a routine evaluation in a spinal cord injury clinic. Although symptomless presentation of a non-leaking abdominal aortic aneurysm is typical in 66–75% of patients without spinal cord injury [2], symptomless presentation of a leaking abdominal aortic aneurysm in neurologically intact patients is very unusual. The lack of symptoms in all patients in the present series, particularly the two cases of leaking or ruptured aneurysm, is instructive and presumably related to the decreased perception of pain in these patients. The lack of symptoms of an abdominal aortic aneurysm in spinal cord injury patients provides further justification for screening ultrasound examination in those who meet the criteria for abdominal aortic aneurysm screening proposed by Krupski [3], namely age >50 years, and a history of hypertension, smoking, coronary artery disease, peripheral vascular disease, or a family history of abdominal aortic aneurysm. The absence of symptoms referable to an abdominal aortic aneurysm should not influence treatment considerations, since decreased pain perception may not allow the patient to be aware of an acutely enlarging or leaking aneurysm. Hypotension and a pulsatile abdominal mass in a spinal cord injury patient should be considered as a ruptured abdominal aortic aneurysm until proven otherwise, despite the complete absence of pain. In fact, the present authors believe that the presence of spinal cord injury represents an additional indication for elective abdominal aortic aneurysm repair. The long-term survival rate after abdominal aortic aneurysm repair in this series of spinal cord injury patients is essentially equivalent to that seen after abdominal aortic aneurysm in neurologically intact CARDIOVASCULAR SURGERY
JUNE 1997 VOL 5 NO 3
patients, which is reported to be 61–64% at 5 years [9, 10]. The main cause of late mortality after abdominal aortic aneurysm in other series is cardiac disease. Cardiac mortality appeared to be a major determinant in long-term survival in patients in the present series, although the cause of death could not be determined in many cases. This study demonstrates that operative treatment of abdominal aortic aneurysms in paraplegic and quadriplegic patients can be performed with a low mortality rate, despite a rather high morbidity rate. Often, these morbidities are related to the previous neurologic injury, with pre-existing pulmonary, cutaneous and urinary tract complications being most prevalent. Hemodynamic instability due to spinal cord injury is not a problem in these patients undergoing aortic surgery since their spinal cord injury is a chronic, compensated state of lowerextremity vasodilatation at the time of their aortic repair. Likewise, the lack of venous thromboembolism in these patients relates to the chronic compensated state of the venous system in patients with chronic spinal cord injury. The high incidence of deep venous thrombosis after acute spinal cord injury is well known; however, the occurrence of such thrombosis in patients with chronic spinal cord injury is much lower, approximating the risk seen in other patients, despite the risk factors of persistent venous stasis and immobility from spinal cord injury [11, 12]. Concern that postoperative infectious complications may result in a high rate of prosthetic graft infections seems unwarranted, since only one patient in this large series developed a graft infection which was diagnosed 4 years postoperatively. It is concluded that abdominal aortic aneurysm repair in spinal cord injury patients can be safely performed with low mortality. The spectrum of postoperative complications is somewhat different from that observed after abdominal aortic aneurysm repair in neurologically intact patients. This study should alert clinicians to these risks, as all are potentially preventable, and should not preclude operative treatment of the aneurysm.
References 1. Bickerstaff, L. K., Hollier, L. H. and Van Peenen, H. J. et al., Abdominal aortic aneurysms: the changing natural history. Journal of Vascular Surgery, 1984, 1, 6–10. 2. Goldstone, J., Aneurysms of the aorta and iliac arteries. In Vascular Surgery: A Comprehensive Review, 2nd edn, ed. W. S. Moore. W.B. Saunders, 1993, pp. 401–423. 3. Krupski, W. C., Abdominal aortic aneurysm: defining the dilemma. Seminars of Vascular Surgery, 1995, 8, 123–155. 4. Longo, W. E., Ballantyne, G. H. and Modlin, I. M., Colorectal disease in the spinal cord patient: an occult diagnosis. Diseases of the Colon and Rectum, 1991, 33, 131–134. 5. Kwaan, J. H., Jones, S. A., Juler, G. L. and Conolly, J. E., Special problems associated with abdominal aneurysmectomy in spinal cord injury patients. British Journal of Surgery, 1976, 63, 916–919.
289
Abdominal aortic aneurysm repair with spinal cord injury: D. L. Jacobs et al. 6. International Classification of Diseases, Ninth Revision, Clinical Modification, 4th edn. Channel Publishing, 1995. 7. Boyle, C. A. and Decoufle, P., National sources of vital status information: extent of coverage and possible selectivity in reporting. American Journal of Epidemiology, 1990, 131, 160. 8. Wade, T. P., El-Ghazzawy, A., Virgo, K. S. and Johnson, F. E., The Whipple resection for cancer in US Department of Veterans Affairs Hospitals. Annals of Surgery, 1995, 221, 241–248. 9. Hollier, L. H. and Wisselink, W., Abdominal Aortic Anuerysm. In Haimovici’s Vascular Surgery Principles and Techniques, 4th edn, ed. H. Haimovici. Blackwell Science, 1996, pp. 797–827. 10. Feinglass, J., Cowper, D., Dunlop, D., Slavensky, R., Martin, G. J. and Pearce, W. H., Late survival risk factors for abdominal
290
aortic anuerysm repair: experience from fourteen Department of Veterans Affairs hospitals. Surgery, 1995, 188, 16–24. 11. Lamb, G. C., Tomski, M. A., Kaufman, J. and Maiman, D., Is chronic spinal cord injury associated with increased risk of venous thromboembolism? Journal of the American Paraplegia Society, 1993, 16, 153–156. 12. Kim, S. W., Charallel, J. T., Park, K. W., Bauerle, L. C., Shang, C. C., Gordon, S. K. and Bauman, W. A., Prevalence of deep venous thrombosis in patients with chronic spinal cord injury. Archives of Physical Medicine and Rehabilitation, 1994, 75, 965– 968. Paper accepted 5 March 1997
CARDIOVASCULAR SURGERY
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Cardiovascular Surgery, Vol. 5, No. 3, pp. 286–290, 1997 1997 The International Society for Cardiovascular Surgery Published by Elsevier Science Ltd. Printed in Great Britain 0967–2109/97 $17.00 + 0.00
Outcome of abdominal aortic aneurysm repair in patients with previous spinal cord injury in the Department of Veterans’ Affairs hospitals D. L. Jacobs, W. E. Longo, G. J. Peterson, L. W. McKirgan, K. S. Virgo and F. E. Johnson Department of Surgery, St Louis University School of Medicine and Surgery Service, John Cochran VA Medical Center, St. Louis, Missouri, USA A retrospective review was carried out to determine the morbidity and mortality of abdominal aortic aneurysm repair in patients with previous spinal cord injury. A population-based study utilizing computer records on all patients in Department of Veterans’ Affairs medical centers from 1987–1991 identified 31 patients with spinal cord injury who underwent subsequent infrarenal abdominal aortic aneurysm repair. Additional information was obtained from individual medical records. Some twenty patients (65%) were paraplegics and 11 (35%) were quadriplegics. Aneurysms were most commonly discovered incidentally during work-up of other conditions. All patients had no symptoms referable to their abdominal aortic aneurysm. In total, 29 patients (94%) underwent elective operations. The complication rate (57%) involved mostly pulmonary, cutaneous or urinary tract morbidity. The 30-day mortality rate was 3% for elective abdominal aortic aneurysm repair. Two patients were operated upon as emergencies for rupture, with one operative death. Long-term follow-up revealed a median survival duration of 5.4 years after aneurysm repair. In conclusion, abdominal aortic aneurysm repair in patients with previous spinal cord injury has a low mortality rate. Postoperative complications are often related to spinal cord injury and are potentially preventable; thus, such injury should not preclude surgical intervention for abdominal aortic aneurysm. 1997 The International Society for Cardiovascular Surgery Keywords: abdominal aortic aneurysm, spinal cord injury
Abdominal aortic aneurysms are estimated to be present in 2–5% of the population aged over 60 years, and the incidence is increasing [1]. Though typically symptom-free unless ruptured, pain from pressure or stretching in the retroperitoneum as the abdominal aortic aneurysm expands, resulting in a diagnosis of a symptomatic, non-ruptured aneurysm, is reported to occur in up to 14% of cases [2]. Symptomless aneurysms are often detected incidentally on plain films of the abdomen when calcification of the aortic wall reveals the aneurysm outline (noted in
Correspondence to: Dr D. L. Jacobs, Department of Surgery, St Louis University School of Medicine, 3635 Vista at Grand Blvd., PO Box 15250, St Louis, MO 63110-0250, USA
286
40% of patients with an abdominal aortic aneurysm), or by ultrasound or computed tomography studies of the abdomen. The reported increased incidence of abdominal aortic aneurysm is in part due to the more frequent incidental diagnosis of the problem as these imaging modalities are used more often. Screening protocols using ultrasound have been proposed for the detection of abdominal aortic aneurysm, particularly for high-risk groups such as patients aged over 50 who have hypertension, coronary artery disease, peripheral vascular disease or a family history of abdominal aortic aneurysm [3]. However, screening of the population in general has not been shown to be cost-effective [3]. Patients with motor-sensory deficits due to spinal cord injury are highly predisposed to develop comCARDIOVASCULAR SURGERY
JUNE 1997 VOL 5 NO 3
Abdominal aortic aneurysm repair with spinal cord injury: D. L. Jacobs et al.
plications such as urinary tract infection, pressure sores, and pneumonia. Due to the high incidence of these complications, such patients often have imaging studies of the abdomen and pelvis; this could potentially result in increased incidental diagnosis of an abdominal aortic aneurysm. Sensory deficits in spinal cord injury patients can make the diagnosis of common diseases challenging [4]. They could also prevent perception of pain associated with an abdominal aortic aneurysm, resulting in a delayed diagnosis of an acutely expanding or ruptured aneurysm. The clinical presentation and outcome of patients with previous spinal cord injury who undergo repair of an abdominal aortic aneurysm is known only by anecdotal reports [5]. This study utilized large computer-based data sets to compile a large, contemporary series of patients with these two diagnoses to better define their clinical course and to provide for management guidelines.
Patients and methods The records of the Department of Veterans Affairs (DVA) from calendar years 1987–1991 were reviewed for this study. The computer-based information was accessed through the DVA Data Processing Center in Austin, Texas. The first data set employed was the Beneficiary Identification and Records Location System (BIRLS), which is the primary source of mortality information on veterans and beneficiaries in the DVA. A second source of information was the Patient Treatment Files (PTF), a database which records information about each episode of inpatient and outpatient care provided under VA auspices. Since information about patients cared for this in this system is available in a standard format through a single, accessible computer system, the two data bases were surveyed to gather data on all those patients with the diagnostic codes (ICD-9-CM) for paraplegia (344.0), or quadriplegia (344.1), and abdominal aortic aneurysm (441.4) and abdominal aortic replacement (38.44) [6]. This allowed identification of patients that had pre-existing spinal cord injury and underwent an abdominal aortic aneurysm repair. No data were obtained on patients with spinal cord injury and abdominal aortic aneurysm who were not operated on for their aneurysm. Data from the DVA hospital system for calendar years 1987– 1991 were chosen to insure a contemporary patient population, and permit adequate follow-up to detect as many late complications as possible. Suitable patients were identified from 14 DVA medical centers. To supplement the computerderived data, additional information was sought from these DVA facilities. A customized standard questionnaire was employed requesting demographic CARDIOVASCULAR SURGERY
JUNE 1997 VOL 5 NO 3
data not obtainable from BIRLS or PTF, as well as copies of discharge summaries, operative reports, and pathology reports. Data obtained included age, sex, date of admission, initial diagnosis, diagnostic procedures and results, operative procedures, operative and postoperative complications, length of stay, length of post-treatment survival and cause of death. Although in-hospital mortality information was available from PTF data, that concerning mortality after discharge was not. BIRLS contains records of all veterans whose beneficiaries applied for death benefits at the time of their demise, whether outside the hospital or within the DVA or other hospitals. The date of death is recorded for each veteran in whose name benefits are requested. A recent comparison of mortality recording systems estimated that 80–89% of all veterans’ death are recorded by BIRLS [7]. The BIRLS mortality information agreed with PTF records when both were available, and there is no suggestion that requests for benefits varies significantly across treatment groups [8]. Finally, US Social Security Administration death records were searched for all patients without a BIRLS death record; those without a record of death in any of the three systems were assumed to be alive. Long-term survival data were compiled and median survival determined using life-table analysis.
Results Between 1 January, 1987 and 31 December, 1991, a total of 50 patients were identified from the PTF with ICD-9-CM diagnostic codes for spinal cord injury, abdominal aortic aneurysm, and such aneurysm repair. Data on 31 (62%) spinal cord injury patients who underwent subsequent infrarenal abdominal aortic aneurysm repair were sufficient for the cases to be evaluable. These 31 patients comprise the study population. The mean duration of followup was 4.4 years. Patient demographics The mean age of the 31 patients in this study was 62 (range 52–71) years; all were males. The mean duration of neurologic deficit prior to surgery was 20 years. Twenty of the patients (65%) were paraplegics; the remaining 11 (35%) were quadriplegics. Two patients had previously had thoracoabdominal aortic aneurysm repairs resulting in postoperative paralysis and subsequently required abdominal aortic aneurysm repair. Symptoms and evaluation At the time of abdominal aortic aneurysm diagnosis, patients often had symptoms related to the urinary tract or pelvic skeleton. None of the 31 patients had symptoms judged by their physicians to be suggestive 287
Abdominal aortic aneurysm repair with spinal cord injury: D. L. Jacobs et al.
of abdominal aortic aneurysm. This was even the case in one patient with a leaking abdominal aortic aneurysm who presented hemodynamically unstable and was thought to have urosepsis. This patient subsequently had the diagnosis of contained rupture of an abdominal aortic aneurysm made several days after admission. Twelve patients (35%) had the aneurysm discovered on physical examination, typically at the time of an annual examination in a spinal cord injury clinic. Aneurysms were also discovered incidentally by abdominal ultrasound (10), pelvic X-ray (five) and abdominal computed tomography scan. One patient presented initially with a femoral pseudoaneurysm and had rupture of an unsuspected abdominal aortic aneurysm while undergoing repair of the femoral aneurysm. The initial diagnoses at the time of presentation are depicted in Table 1. The mean aneurysm size was 6.1 (range 4.5–11) cm. Twenty-five patients (81%) underwent computed tomography scan; 20 (65%) underwent arteriography to delineate the extent of the abdominal aortic aneurysm and any associated arterial occlusive disease. Treatment and outcome Twenty-nine patients (94%) underwent elective operation; two were operated on as emergencies for rupture. Twenty one (68%) repairs were tube grafts and the remaining 10 were bifurcated grafts. One patient died of a myocardial infarction 3 weeks after elective abdominal aortic aneurysm repair, yielding a 30-day mortality rate for this situation of 3%. Of the two patients operated on as emergencies, one died from loss of blood. Operative management of these patients did not reveal difficulties with unusual declamping hypotension due to decreased vasomotor tone in the denervated lower extremities. Utilization of vasopressor drugs in the perioperative period was common, but dosages and duration of use was not well docu-
mented. The methods of deep venous thrombosis prophylaxis used were not able to be determined; however, none of the patients had documentation of a postoperative deep venous thrombosis or pulmonary embolism. A complication rate of 57% was observed and involved mostly infectious pulmonary, cutaneous or urinary tract morbidity which was related to complications of spinal cord injury present before abdominal aortic aneurysm repair. One patient required an above-knee amputation in the early postoperative period due to a pre-existing decubitus ulcer which precluded limb salvage. One patient developed renal failure secondary to acute tubular necrosis but had complete recovery of renal function after 6 weeks. Two patients developed acute postoperative graft thrombosis: one required revision of a tube graft to an aortobifemoral graft, and a second required thrombectomy of an aortobifemoral graft. The overall mean hospital stay was 43 (range 7–210) days. Extended length of stay was related to the high incidence of postoperative complications noted above. Long-term follow-up revealed a median survival of 5.4 years. The survival curve is depicted in Figure 1. One patient developed a late graft infection 4 years postoperatively.
Discussion The rising sophistication of computer-based data sets, the ever-increasing depth of available data, and the current level of skill in extracting data from such resources, enhances the ability to obtain information on meaningfully large populations of patients with unusual constellations of diagnoses of interest. In the present study there was heavy reliance on computer searches of very large data sets to identify the patient
Table 1 Initial diagnoses* in spinal cord injury patients at the time of incidental diagnosis of an abdominal aortic aneurysm Initial diagnosis
No. of patients
Nephrolithiasis Trauma/fracture Cholecystitis Urosepsis Abdominal malignancy Arterial occlusive disease Rectal prolapse Femoral artery pseudoaneurysm
10 (32) 4 (13) 3 (10) 2 (6) 2 (6) 1 (3) 1 (3) 1 (3)
*Seven patients (23%) had their abdominal aortic aneurysm discovered at the time of a health maintenance examination in a spinal cord injury clinic and had no other diagnoses noted at that time. Values in parentheses are percentages.
288
Figure 1 Life-table survival curve after abdominal aortic aneurysm repair in patients with previous spinal cord injury
CARDIOVASCULAR SURGERY
JUNE 1997 VOL 5 NO 3
Abdominal aortic aneurysm repair with spinal cord injury: D. L. Jacobs et al.
population and to provide basic clinical, demographic and survival information. The information available in these datasets was supplemented with additional clinical data from the clinical records, in order to maximize the accuracy of the information presented. The diagnosis of abdominal aortic aneurysm in spinal cord injury patients was most often made incidentally during imaging studies performed to evaluate pathologies related to their neurologic injury. The most common initial diagnosis was nephrolithiasis, (32.7%) (Table 1). Routine ultrasound on an annual basis to screen for nephrolithiasis was the most common reason for obtaining the imaging study that resulted in the diagnosis of abdominal aortic aneurysm. The relatively frequent evaluation of these patients by such surveillance appears to have resulted in the diagnosis of abdominal aortic aneurysms that otherwise would have gone undetected. Approximately one-third of patients had their abdominal aortic aneurysm diagnosed on physical examination, the majority of which were performed as part of a routine evaluation in a spinal cord injury clinic. Although symptomless presentation of a non-leaking abdominal aortic aneurysm is typical in 66–75% of patients without spinal cord injury [2], symptomless presentation of a leaking abdominal aortic aneurysm in neurologically intact patients is very unusual. The lack of symptoms in all patients in the present series, particularly the two cases of leaking or ruptured aneurysm, is instructive and presumably related to the decreased perception of pain in these patients. The lack of symptoms of an abdominal aortic aneurysm in spinal cord injury patients provides further justification for screening ultrasound examination in those who meet the criteria for abdominal aortic aneurysm screening proposed by Krupski [3], namely age >50 years, and a history of hypertension, smoking, coronary artery disease, peripheral vascular disease, or a family history of abdominal aortic aneurysm. The absence of symptoms referable to an abdominal aortic aneurysm should not influence treatment considerations, since decreased pain perception may not allow the patient to be aware of an acutely enlarging or leaking aneurysm. Hypotension and a pulsatile abdominal mass in a spinal cord injury patient should be considered as a ruptured abdominal aortic aneurysm until proven otherwise, despite the complete absence of pain. In fact, the present authors believe that the presence of spinal cord injury represents an additional indication for elective abdominal aortic aneurysm repair. The long-term survival rate after abdominal aortic aneurysm repair in this series of spinal cord injury patients is essentially equivalent to that seen after abdominal aortic aneurysm in neurologically intact CARDIOVASCULAR SURGERY
JUNE 1997 VOL 5 NO 3
patients, which is reported to be 61–64% at 5 years [9, 10]. The main cause of late mortality after abdominal aortic aneurysm in other series is cardiac disease. Cardiac mortality appeared to be a major determinant in long-term survival in patients in the present series, although the cause of death could not be determined in many cases. This study demonstrates that operative treatment of abdominal aortic aneurysms in paraplegic and quadriplegic patients can be performed with a low mortality rate, despite a rather high morbidity rate. Often, these morbidities are related to the previous neurologic injury, with pre-existing pulmonary, cutaneous and urinary tract complications being most prevalent. Hemodynamic instability due to spinal cord injury is not a problem in these patients undergoing aortic surgery since their spinal cord injury is a chronic, compensated state of lowerextremity vasodilatation at the time of their aortic repair. Likewise, the lack of venous thromboembolism in these patients relates to the chronic compensated state of the venous system in patients with chronic spinal cord injury. The high incidence of deep venous thrombosis after acute spinal cord injury is well known; however, the occurrence of such thrombosis in patients with chronic spinal cord injury is much lower, approximating the risk seen in other patients, despite the risk factors of persistent venous stasis and immobility from spinal cord injury [11, 12]. Concern that postoperative infectious complications may result in a high rate of prosthetic graft infections seems unwarranted, since only one patient in this large series developed a graft infection which was diagnosed 4 years postoperatively. It is concluded that abdominal aortic aneurysm repair in spinal cord injury patients can be safely performed with low mortality. The spectrum of postoperative complications is somewhat different from that observed after abdominal aortic aneurysm repair in neurologically intact patients. This study should alert clinicians to these risks, as all are potentially preventable, and should not preclude operative treatment of the aneurysm.
References 1. Bickerstaff, L. K., Hollier, L. H. and Van Peenen, H. J. et al., Abdominal aortic aneurysms: the changing natural history. Journal of Vascular Surgery, 1984, 1, 6–10. 2. Goldstone, J., Aneurysms of the aorta and iliac arteries. In Vascular Surgery: A Comprehensive Review, 2nd edn, ed. W. S. Moore. W.B. Saunders, 1993, pp. 401–423. 3. Krupski, W. C., Abdominal aortic aneurysm: defining the dilemma. Seminars of Vascular Surgery, 1995, 8, 123–155. 4. Longo, W. E., Ballantyne, G. H. and Modlin, I. M., Colorectal disease in the spinal cord patient: an occult diagnosis. Diseases of the Colon and Rectum, 1991, 33, 131–134. 5. Kwaan, J. H., Jones, S. A., Juler, G. L. and Conolly, J. E., Special problems associated with abdominal aneurysmectomy in spinal cord injury patients. British Journal of Surgery, 1976, 63, 916–919.
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CARDIOVASCULAR SURGERY
JUNE 1997 VOL 5 NO 3