Asian Cardiovasc Thorac Ann 2008;16:33-36
© 2008 Asia Publishing EXchange Ltd
Is Treatment of Acute Type A Aortic Dissection in Septuagenarians Justifiable?
Malakh Shrestha, MBBS,
Nawid Khaladj, MD,
Axel Haverich, MD,
Christian Hagl, MD
Division of Cardiac, Thoracic, Transplantation and Vascular Surgery, Hannover Medical School, Hannover, Germany
For reprint information contact: Malakh Shrestha, MBBS Tel: 49 511 532 2157 Fax: 49 511 532 5404 Email: Malawshr{at}yahoo.com, Division of Cardiothoracic and Vascular Surgery, Hannover Medical School, Carl Neuberg Str. 1, 30625 Hannover, Germany.
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ABSTRACT
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This study was undertaken to analyze the risk of mortality and neurological complications after treatment of acute type A aortic dissection in septuagenarians. From 1996 through 2002, 24 patients > 70 years underwent surgery for acute type A aortic dissection. Their median age was 75 years (range, 71–82 years), and 15 were male. Eleven (46%) had previous neurological events, 22% presented with hemodynamic instability and aortic rupture was found in 7%. Ten had hypothermic circulatory arrest alone, 3 had it in combination with retrograde cerebral perfusion and 11 had selective antegrade cerebral perfusion as an adjunct. The overall survival rate was 71% (17/24). Temporary neurological dysfunction was found in 3 (12.5%), and permanent neurological dysfunction in 9 (37.5%), leading to death in 3. Comparison of mortality rates and neurological outcome showed a marked tendency towards better outcome in patients who had hypothermic circulatory arrest and selective antegrade cerebral perfusion. Surgery for aortic dissections in the elderly can be performed with acceptable mortality, but there is a high rate of neurological complications. Despite the small number of patients, selective antegrade cerebral perfusion seemed to reduce the incidence of neurological events.
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INTRODUCTION
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Increasing life expectancy and better health status of the population, especially in the industrialized world, have raised a number of ethical and medical questions regarding indications for surgery in older patients. These questions can best be answered objectively by examining the results of surgical procedures in the elderly. From the 7th decade of life, patients are usually at higher surgical risk due to significant comorbidity from age-related factors. In patients undergoing major surgery on the aorta, which requires periods of hypothermic circulatory arrest (HCA), a clear correlation has been established between age and the incidence of both permanent stroke and death.1,2 The incidence of temporary neurological dysfunction (TND) has also been shown to increase with age.1,3 Frank stroke is usually the result of an embolic event, and neurological symptoms depend on the location and size of the defect as well as on individual patient variables. Magnetic resonance imaging can detect it as early as 12–18 hours after the event; CT scanning is usually positive after 24–48 hours. Temporary neurological dysfunction is a reflection of imperfect brain protection during circulatory arrest, as demonstrated by a highly significant correlation between TND and duration of HCA in several reports.1,2 Although there have been studies on cardiac surgery in older patients, there have been few dealing with the outcome of aortic dissection surgery in this age group. This single-center retrospective review was undertaken to analyze the risk of mortality, morbidity, and neurological complications after treatment of acute type A aortic dissections using HCA in patients > 70 years of age.
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PATIENTS AND METHODS
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Between January 1996 and December 2002, 24 patients > 70 years old with type A aortic dissection were operated on at the Hannover Medical School. Data that were entered contemporaneously in our departmental database were reviewed retrospectively and supplemented from patient records. Preoperative data are shown in Table 1
. Ten patients had HCA alone, 3 had it in combination with retrograde cerebral perfusion and 11 had selective antegrade cerebral perfusion as an adjunctive.
The surgical approach was via a median sternotomy. The femoral artery or ascending aorta was used for arterial cannulation, according to the surgeon’s preference. Direct cannulation of the ascending aorta under echocardiographic control allows identification of the false and true lumens and can be helpful in determining the correct cannulation site. If malperfusion was encountered (as assessed by pressure monitoring in both radial arteries), the pump was stopped, the arch was opened, and an incision was made in the membrane between the true and false lumens. Thereafter, cardiopulmonary bypass was re-established. Hypothermic circulatory arrest was used to inspect the aortic arch in all patients. Before HCA, methylprednisolone 2 g was given, with an additional 1.5 g during the next 48 hours if HCA time exceeded 30 min. In patients who had retrograde cerebral perfusion in addition to HCA, cerebral perfusion was established after the start of HCA, to avoid embolic strokes. A cannula was placed in the superior vena cava, and the flow was adjusted to achieve a pressure of 15–20 mm Hg in the superior vena cava. In cases where selective antegrade cerebral perfusion was also given, special catheters (RCSP MR 20, 15F; Medtronic Inc., Minneapolis, MN, USA) were introduced under direct vision via the opened aortic arch into the innominate and left carotid arteries during a 3–5 min interval of HCA. After meticulous de-airing, perfusion was started at a flow rate of 10 mL · kg–1 · min–1 and adjusted to maintain the pressure in the right radial artery at 40–60 mm Hg. If the backflow from the left subclavian artery compromised the surgical field, it was occluded with a Fogarty catheter. This technique offers a relatively uncompromised surgical field, avoids clamp injuries of the arteries, and minimizes the risks of microembolic events.4 The continuous observation of pump flow, pressure and oxygen saturation allows the anesthesiologist to treat the consequences of vagaries of vasomotor tone, which can occur during selective antegrade cerebral perfusion. The decision regarding the extent of surgery depended on the pathology. A valve-sparing operation was applied whenever possible. The aortic arch was replaced when re-entry was in the arch. Gelatin-resorcin-formalin glue was used to readapt the distal dissected ends of the false lumen, the glued stumps were reinforced with felt strips, and the dissected aorta was replaced with a Dacron graft. Concomitant coronary artery bypass grafting was performed only when significant coronary artery disease or dissection of the coronary ostium was present.
Adverse outcome was defined as intraoperative or hospital death, or permanent neurological injury. A stroke was considered permanent when patients were discharged with residual neurological symptoms. Temporary neurological dysfunction was analyzed separately in all patients surviving the operation, excluding those who suffered strokes or who did not regain consciousness. Temporary neurological dysfunction was defined as postoperative confusion, agitation, delirium, prolonged obtundation, or Parkinson-like symptoms, with no focal deficit in computed tomography or magnetic resonance imaging. Hemodynamic instability was defined as the need for inotropic support to maintain mean arterial pressure > 60 mm Hg. New neurological symptoms were those occurring together or as a symptom of the dissection. Results are expressed as mean ± standard deviation, or median and range. Due to the limited number of patients, only descriptive statistics have been used.
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RESULTS
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Intraoperative and postoperative data are listed in Table 2 and Table 3. The overall survival rate was 71% (17/24). Temporary neurological dysfunction was found in 3 (12.5%) patients and stroke in 9 (37.5%), leading to death in 3. Comparison of mortality rates between patients treated with HCA alone and those who had HCA and selective antegrade cerebral perfusion showed a marked tendency towards a better outcome in those who had selective antegrade cerebral perfusion; TND and stroke were also markedly reduced in this group. Due to the limited number of patients, no statistically significant factors could be identified for respiratory failure and mortality.
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DISCUSSION
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With the increasing proportion of septuagenarians, the number of patients referred for surgery for type A aortic dissection has grown. Whether or not it is a good idea to undertake surgery in these elderly patients has to be evaluated more carefully, not only because of limited resources, but also because it is unclear whether the outcome always justifies the attempt. In 10,860 patients undergoing coronary bypass operations, Puskas and colleagues5 found that age was a strong predictor of postoperative stroke. This led to debate on whether elderly patients should be accepted for cardiac surgery.
Type A aortic dissection repair in septuagenarians can be performed with acceptable mortality. However, morbidity and mortality are considerably higher in elderly patients and hospitalization is usually prolonged. We did not limit ourselves to ascending aortic replacement only on the basis of age, as described by Caus and colleagues.6 Type A aortic dissection is an absolute emergency with an extremely dismal outcome without surgery. It frequently requires periods of HCA, with a high incidence of postoperative neurological complications, especially in older patients; both neurological complications and death increase with age.1,2 During the study period, no patient was refused surgery at our center because of advanced age, but we cannot assess the possibility of selection of better risk patients by referring physicians. A high incidence of TND in this study was also noted, reflecting the vulnerability of the brain in geriatric patients. Prolonged obtundation may also be related to the slower metabolism of anesthetic drugs in the elderly. To reduce the incidence of TND, our current strategy of cerebral protection relies principally on selective antegrade cerebral perfusion as an adjunct to HCA when longer durations of HCA are anticipated.
From our experience, there seems to be no justification for refusing to operate on a patient with acute type A dissection just because of age, especially as the prognosis is dismal without surgery. The international registry of aortic dissection shows that only 42% of patients treated by intensive medical therapy were discharged from hospital. Therefore, Centofanti and colleagues7 recommended that when the expected mortality is 58% or less, surgery is always indicated. In our series, septuagenarians undergoing type A aortic dissection surgery had hospital mortality of 29% (7/24); this agrees with reported rates of 20.5% to 37.3%.6–9 During the same time period (1996–2002), we had hospital mortality of 15.5% (21/135) in patients < 70 years old who were operated on for type A aortic dissection. Shiono and colleagues10 had only 13% hospital mortality in older patients but they operated on only 24 of 41 patients admitted, whereas we did not refuse surgery to any patient. In other studies, it was unclear whether older patients were preselected for surgery.11 Nevertheless, such operations have a high risk of adverse outcome, and the decision to operate should be considered carefully. Furthermore, this operation is associated with a significant incidence of TND and prolonged intensive care unit stay, which may cause secondary complications. Although the overall incidence of adverse outcome in this geriatric cohort is high, the enhanced vulnerability of the brain in the elderly is reflected by a high early mortality after stroke and a very high incidence of TND. Despite the small number of patients in this study, it seems that selective antegrade cerebral perfusion as an adjunct to HCA may reduce the incidence of neurological events.
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REFERENCES
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ABSTRACT
INTRODUCTION
