Ann Thorac Surg 2006;82:554-559
© 2006 The Society of Thoracic Surgeons
Original article: Cardiovascular
Emergency Surgery for Acute Type A Aortic Dissection in Octogenarians
Motomi Shiono, MD, PhD*,
Mitsumasa Hata, MD, PhD,
Akira Sezai, MD, PhD,
Mitsuru Iida, MD, PhD,
Shinya Yagi, MD, PhD,
Nanao Negishi, MD, PhD
Department of Cardiovascular Surgery, Nihon University School of Medicine, Tokyo, Japan
Accepted for publication December 13, 2005.
* Address correspondence to Dr Shiono, Department of Cardiovascular Surgery, Nihon University School of Medicine, 30-1 Oyaguchi-kamimachi, Itabashi-ku, Tokyo 173-8610, Japan (Email: mshiono{at}med.nihon-u.ac.jp).
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Abstract
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BACKGROUND: Emergency surgery for acute type A dissection is associated with a high mortality rate in aged patients. This study was designed to explore perioperative risk factors and prognosis in octogenarians with acute type A aortic dissection.
METHODS: Twenty-four octogenarians, of 134 consecutive patients with acute type A dissection between 1995 and 2005 who underwent emergency surgery, were reviewed. The median age was 82 years (80 to 90); the patients were 10 men and 14 women. All 24 patients underwent conservative tear-oriented surgery under deep hypothermic circulatory arrest with cerebral perfusion; the procedures were 23 ascending aortic replacements and one entire arch replacement.
RESULTS: The hospital mortality rate was 13% (3 of 24 patients), without statistical significance compared with 6% in patients younger than 80 years. The late mortality rate was 38% (9 of 24 patients), with significance compared with 9% in the other patients. Five- and 10-year survivals ware 55% and 42%, respectively, compared with 83% and 73%, respectively (p = 0.0013), in the other patients. Univariate and multivariate analysis demonstrated that age 80 or greater was not an independent risk factor of hospital death. Risk factors of late death in younger-aged patients were pneumonia and reoperation.
CONCLUSIONS: Emergency surgery for octogenarians with acute type A aortic dissection was successfully performed using a conservative intimal tear-oriented procedure, resulting in satisfactory early and late survival. Aggressive surgical treatment is mandatory for improving the outcome of this medical emergency in octogenarians.
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Introduction
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Acute type A aortic dissection is a lethal aortic disease with an extremely poor prognosis unless surgical intervention is performed in a timely manner. Many predictors of death have been evaluated for patients in acute aortic dissection with or without surgery [1–4]. Most studies indicate that older age is a risk determinant of early death [2, 4–6]. With progressive aging of the population, many physicians are increasingly faced with this medical emergency in these high-risk patients. Controversy still exists as to whether surgical intervention should be avoided in elderly patients who have little chance of survival. However, recent progress in emergency surgery for acute aortic dissection has resulted in a significant decline in operative and hospital mortality. This study was undertaken to analyze a consecutive series of patients aged 80 years or older with acute type A aortic dissection, aiming to improve outcome in these high-risk patients, with a comparison to younger patients.
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Patients and Methods
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Patients
Twenty-four consecutive patients aged 80 years or older, who underwent emergency surgery for acute type A aortic dissection at our institution from July 1995 to June 2005, were reviewed retrospectively and compared with patients younger than 80 years. Institutional review board approval was provided before publication of this manuscript and report of the information. The older patients represented 17.9% of a total of 134 consecutive patients who underwent emergency surgery for acute type A aortic dissection in the same period. Forty-one octogenarians who presented with acute type A dissections were observed during the same period. Ten patients were not offered surgery because the false channel revealed thrombosed occlusion without pericardial effusion or tamponade. Seven patients refused surgery because of age or concomitant disease, and 6 patients died in hospital. None of the patients younger than 80 years refused operation. After obtaining the informed consent, all of the operations were performed within 72 hours of onset, with a mean of 16.5 hours after onset. One hundred eleven patients (82%) were operated on within 24 hours after onset, 13 patients (10%) between 24 and 48 hours, and 9 patients (8%) between 48 and 72 hours. The clinical characteristics and perioperative variables of the older patients, consisting of 10 men and 14 women, are presented in Table 1. Their age ranged from 80 to 90 years, with a mean of 82.0 years. Pain in the chest and back was the common presenting symptom. Computed tomography scan and echocardiography were the common diagnostic modalities before emergency surgery. When the false channel revealed thrombosed occlusion, the operation was postponed, unless pericardial effusion was not detected. When the diagnosis was confirmed by these diagnostic modalities, the patient was transferred to the operating room as soon as possible.
Surgery and Follow-Up
Cardiopulmonary bypass was initiated by means of femorofemoral cannulation for patients in preoperative shock. After a median sternotomy was performed, a venous cannula was inserted through the right atrium, in the cases with stable hemodynamic condition. In all of the patients of both age groups, deep hypothermic circulatory arrest and antegrade selective cerebral perfusion were used, and the heart was arrested with cold crystalloid cardioplegia. Under deep hypothermia less than 20°C, the aortic segment that included the intimal tear was resected. Gelatin-resorcin-formalin glue was applied to both the proximal and distal dissected ends of the false lumen, and then the glued stumps were reinforced with felt strips, and the resected aorta was replaced with a presealed woven polyethylene terephthalate fiber (Dacron) graft (Boston Scientific, Inc, Natick, MA). Antegrade arterial circulation was established through a side branch of the Dacron graft, after completion of an open distal anastomosis. In cases in which the intimal tear could not be found, only ascending aortic replacement was performed to avoid serious complications.
We examined the patients at our outpatient clinic or contacted the physicians treating them for follow-up. The retrospective postoperative follow-up rate was 100% for up to 10 years (419.7 patient-years).
Statistical Analysis
Statistical analysis was performed with StatView software (SAS Institute Inc, Cary, NC). All pertinent perioperative risk factors for death were examined by 
2 test or Fisher's exact test, as appropriate; continuous variables were examined by Student's t test, and the results were expressed as percentage and the mean ± standard deviation, respectively. Univariate analysis was followed by multiple logistic regression to determine independent risk factors. Actuarial survival and freedom rates from events were calculated by the Kaplan–Meier method, and the log-rank test (Mantel–Cox test) was used for comparison between the two age groups. A value of p less than 0.05 was considered statistically significant.
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Results
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Patients and Surgery Data
The two age groups (80 years or older, and younger than 80 years) examined were not significantly different from each other with respect to the majority of perioperative variables, except for age, the extent of aortic replacement, and cardiopulmonary bypass time. Although the hospital mortality rate (3 of 24 patients; 13%) was not statistically different, the late mortality rate (9 of 24 patients; 38%) and nonvascular-related mortality (6 of 24 patients; 25%) were significantly worse in the older age group (p = 0.0003 and 0.0001, respectively).
In the older patients, the operation was mostly limited to replacement of the ascending or hemiarch aorta in 23 patients (96%), and entire replacement of the aortic arch was necessary in 1 patient (4%), although replacement of the entire aortic arch was performed in 28 patients (26%) in the younger patients (p = 0.03). Cardiopulmonary bypass time was shorter in the older patients (p = 0.02). There were no significant differences in concomitant procedures, impossible entry resection, and myocardial ischemic time (Table 1).
Mortality and Events
The hospital mortality rate was 13% (3 of 24 patients) in the older patients; causes of deaths were multiple-organ failure (2 patients) and pneumonia (1 patient). The hospital mortality rate in the younger patients was 6% (6 of 110 patients); their causes of death were low cardiac output syndrome (2 patients), multiple-organ failure (1 patient), hepatic failure (1 patient), bleeding (1 patient), and pulmonary hypertensive crisis (1 patient). There was no significant difference in the hospital mortality between the two age groups (p = 0.36). The late mortality rate in the older patients was 38% (9 of 24 patients) after discharge from the hospital. The causes of late deaths were pneumonia (3 patients), spontaneous death by senility (2 patients), stroke (1 patient), gallbladder cancer (1 patient), arrhythmia (1 patient), and ileus (1 patient). The causes of deaths in the younger patients were reoperation (2 patients), mediastinitis (1 patient), stroke (1 patient), pancytopenia (1 patient), pneumonia (1 patient), rupture of the thoracic aorta (1 patient), sepsis (1 patient), rupture of an abdominal aortic aneurysm (1 patient), and spinal cord tumor (1 patient). The late mortality rates between the two age groups were significantly different (p = 0.0004).
Major events, including late deaths, occurred in 25 patients after discharge from the hospital, in both groups of patients. In the older patients, all of such major events, including pneumonia (3 patients), spontaneous death by senility (2 patients), stroke (1 patient), cancer (1 patient), arrhythmia (1 patient), and ileus (1 patient), were lethal. In the younger patients, 10 deaths and eight reoperations occurred during follow-up. Reoperations were performed because of enlargement of the distal false lumen in 5 patients, enlargement of the aortic root in 2 patients, and aortic valve regurgitation in 1 patient.
Actuarial Survival and Event-Free Rates
Actuarial survival rates (including hospital mortality) of the older patients at 5 and 10 years after surgery were 55% and 42%, respectively. In the younger patients, actuarial survival rates at 5 and 10 years were 83%, and 73%, respectively. Log-rank test indicated a significant difference in the actuarial survival rates between the two groups (p = 0.0013). The actuarial survival curves for the two groups are shown in Figure 1.
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Fig 1. Actuarial survival curve for the two age groups (80 years or older, and younger than 80 years) after emergency surgery for acute type A aortic dissection.
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Actuarial event-free rates at 5 and 10 years after surgery were 55% and 41%, respectively, in the older patients, and 78% and 48%, respectively, in the younger patients. Log-rank analysis indicated a significant difference in the actuarial freedom rates between the two groups (p = 0.017). The event-free curves for the two groups are shown in Figure 2.
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Fig 2. Event-free curve for the two age groups (80 years or older, and younger than 80 years) after emergency surgery for acute type A aortic dissection.
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Risk Factor Analysis on Hospital and Late Mortality
In the older patients, univariate and multivariate analysis of perioperative risk factors demonstrated no independent factors that were associated with hospital mortality (Table 2). In the younger patients, the independent risk factor was postoperative hemodialysis (p = 0.04; odds ratio, 1.98; 95% confidence interval, 1.02 to 35.4). In the older patients, the independent risk factor that was associated with late mortality was female sex (p = 0.04; odds ratio, 2.10; 95% confidence interval, 1.18 to 122.3; Table 3). In the younger patients, postoperative pneumonia (p = 0.0007; odds ratio, 3.41; 95% confidence interval, 3.54 to 108.2) and reoperation (p = 0.0007; odds ratio, 3.54; 95% confidence interval, 4.09 to 134.7) were independent risk factors associated with late mortality.
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Comment
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According to the International Registry of Acute Aortic Dissection (IRAD) database, logistic regression identified age 70 years and older as one predictor of death in type A dissection [1], and mortality of patients managed surgically was 26% [2]. Most articles consistently report hospital mortality exceeding 15% in Western countries [2, 4–6]. Recent technical improvements in emergency surgery for acute aortic dissection have resulted in a marked decline in hospital mortality.
In this study, the hospital mortality rate was remarkably low, and older age was not associated with an increase in the hospital mortality rate in acute type A aortic dissection, as Hagl and Griepp [7] have reported. Postoperative hemodialysis was found to be a statistically significant risk factor for hospital death in our younger population. Although cardiac tamponade was not a significant risk factor in this study, protracted dissection-related complications, such as tamponade or shock and visceral ischemia, are a major concern that would have an effect on hospital mortality and morbidity [2, 8–10]. Early recognition of the disease with noninvasive diagnostic modalities, such as computed tomography scans and echocardiography, and earlier referral to surgical units have been improving the surgical results before dissection-related complications become irreversible. In our series of patients, 82% of patients (n = 110) underwent emergency surgery within 24 hours of onset, which has been considered one of the key factors of success. Postoperative hemodialysis also contributes to hospital mortality as a result of hemodynamic instability during dialysis, consequently resulting in multiple-organ failure.
Transverse arch replacement, which required longer cardiopulmonary bypass time, was performed in only 1 patient in our older group (4%), whereas it was performed in 28 of the younger patients (25%). In the majority of patients, a partial or hemiarch replacement is sufficient, as the intimal tear is generally located in the ascending aorta or the proximal aortic arch [3]. In this study, resection of the primary intimal tear was performed successfully in 23 patients (96%). The extent of aortic replacement and period of surgery have been reported as significant risk factors for hospital mortality in previous reports [3, 11, 12]. All of our patients underwent glue-aided repair for the dissected aortic wall and the aortic valve because glue-aided repair is simple and time-saving. Because the principal object of emergency surgery for acute dissection is saving the patient's life, conservative tear-oriented procedure, which reduces the time of surgery, may be appropriate [13], especially in older patients.
Since hypothermic circulatory arrest was successfully introduced for aortic surgery and modified [14], circulatory arrest provides easier and more extensive aortic repair. However, hypothermic circulatory arrest alone without providing for cerebral perfusion could not diminish high rates of brain damage and mortality rates [15]. In this study, we have adopted antegrade cerebral perfusion because of its physiology and time limitation for brain protection. Because of antegrade cerebral perfusion, longer and more extended repair can be performed as a safe and easily reproducible surgical procedure [9, 16, 17]. Dissection-related organ malperfusion as a major concern refers to organ malperfusion that will have an effect on hospital mortality and morbidity [2, 8–10]. Antegrade arterial perfusion provides a better solution for intraoperative malperfusion by femoral artery perfusion. There were no serious complications owing to organ malperfusion in all of our patients who underwent antegrade aortic perfusion after the open distal anastomosis. We could dramatically reduce the surgical mortality because we have benefited greatly from these improvements, including open distal anastomosis using hypothermic circulatory arrest with antegrade cerebral perfusion, gelatin-resorcin-formalin glue, and antegrade arterial perfusion. Also, tear-oriented conservative surgery has provided satisfactory surgical results, especially in older patients.
The late survival in our older patients was considered acceptable, but it was significantly poorer compared with the younger patients (p = 0.0016). The results are comparable with previous reports describing 5-year survival rates of 50% to 80% in all age groups [5, 11, 16, 18]. In this study, three independent risk factors for late death were female sex in the older patients, and pneumonia and reoperation in the younger patients. A high prevalence of aspiration pneumonia was observed even after discharge from the hospital, and therefore strict long-term respiratory care and prevention of pneumonia are required to improve late results. The critical influence of older age as an important risk factor for late death was demonstrated in our study; however, significant improvement in long-term mortality is considered difficult because this factor of older age includes physiologic and pathologic factors related to the normal degenerative process of senescence. There were no reoperations in the older group, although 8 patients required reoperation in the younger patients. Reoperation is a major risk factor for late death in all patients, even when initial emergency operation has been successfully performed.
Our long-term survival rate of octogenarians is comparable to those in other types of elective coronary and valve procedures [19, 20]. Among 12 survivors, follow-ups have been continued in the outpatient clinic (n = 6), nursing homes (n = 4), and care at home (n = 2). Assessment of postoperative quality of life revealed that half of the patients remained autonomous; however, currently dementia (n = 6) and depression (n = 2) have been observed in the survivors. Impaired autonomy or bedridden status after emergency operation is another concern, and therefore fully informed consent that describes the prognosis after emergency operation is mandatory for aggressive surgical treatment.
In conclusion, the hospital mortality could be reduced dramatically in octogenarians with acute type A aortic dissection because of earlier operation and use of a tear-oriented procedure; however, late mortality remained unsatisfactory compared with younger patients. Aggressive emergency surgery is the only option that will provide a reasonable chance of survival for these high-risk patients with an otherwise dismal prognosis. In older patients, a conservative tear-oriented approach is recommended.
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Acknowledgments
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The authors are grateful to Kaname Hirayanagi, PhD, for his statistical review for this study.
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References
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Abstract
Introduction
