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Eur J Cardiothorac Surg 2001;20:1194-1198
© 2001 Elsevier Science NL
a Department of Emergency Medicine, University Clinics, Vienna General Hospital, 1090 Vienna, Austria
b Department of Internal Medicine II/Division of Angiology, University Clinics, Vienna General Hospital, 1090 Vienna, Austria
c Department of Surgery/Division of Cardio-Thoracic Surgery, University Clinics, Vienna General Hospital, 1090 Vienna, Austria
Received 21 May 2001; received in revised form 21 September 2001; accepted 25 September 2001.
Corresponding author. Tel.: +43-1-40400-1964; fax: +43-1-40400-1965
e-mail: hans.domanovits{at}akh-wien.ac.at
| Abstract |
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Key Words: Acute aortic dissection Cardiac tamponade Multiple organ failure Hospital mortality
| 1. Introduction |
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Previous studies examined several potential predictors of outcome in patients with acute type A aortic dissection [4,610]. Rupture of the ascending aorta, often being the cause of cardiac tamponade in type A dissection [1,6,11], was not found to be an independent risk factor for poor outcome [4]. However, cardiac tamponade accounts for a considerable proportion of in-hospital deaths in these patients [6,12].
The aim of the present study was to investigate whether in patients with acute type A aortic dissection the occurrence of preoperative cardiac tamponade with palpable pulses (referred to as impending cardiac tamponade) or without palpable pulses (referred to as severe cardiac tamponade) is associated with poor outcome and to assess preoperative prognostic parameters in these patients.
| 2. Methods |
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2.2. Patients
Within a period of 8 years, from December 1991 to December 1999, 353 patients were admitted with the diagnosis of acute aortic disease to the Department of Emergency Medicine at the Vienna University Hospital. These patients were systematically documented in an aneurysm registry and data collection followed a standardized protocol. Aortic disease was categorized as aortic aneurysm and aortic dissection. Aortic dissection was classified according to the Stanford classification [13].In the present analysis all patients with type A aortic dissection who were admitted via the emergency department (ED) and who were scheduled for emergency surgery were included. Inclusion was based on the intention to treat by surgery. Diagnosis of aortic dissection and cardiac tamponade was made by computed tomography, transthoracal or transesophageal echocardiography, magnetic resonance imaging or by combinations of these. Cardiac tamponade was classified as follows: absent, if no pericardial effusion could be detected by echocardiography, impending, in cases with echocardiographic signs of pericardial fluid with palpable pulses, and as severe cardiac tamponade in patients with cardiac tamponade without palpable pulses [14]. Atherothrombotic risk factors, cardiovascular comorbidities, blood pressure, heart rate, oxygen saturation, and body temperature at admission as well as perioperative data of all patients were recorded. Need for mechanical ventilation, signs of hemodynamic shock at the ED and performance of cardiopulmonary resuscitation in these patients were recorded. Time interval from ED admission to surgery was documented. Patients were followed until hospital discharge for the occurrence of multiple organ failure and death.
2.3. Definitions
Hemodynamic shock was defined as a permanent deterioration in systolic blood pressure below 90 mmHg at the ED. Multiple organ failure (MOF) and/or death was defined as the combined study endpoint. MOF was defined as occurrence of two or more of the following conditions: Acute respiratory distress syndrome (ARDS) [15], acute liver failure [15], acute renal failure (ARF) [16], acute heart failure [15,17], diffuse or focal neurologic ischemic damage, such as persistent paraparesis or paraplegia due to impairment of blood supply to the spinal cord [12] or signs of central neurological damage following cerebral hypoperfusion [15], and septicemia [18].
2.4. Statistical analysis
Continuous values are presented as median and the interquartile range (range from the 25th to the 75th percentile). Percentages were calculated for dichotomous variables. Cardiac tamponade was analyzed as a categorical variable according to absent, impending, and severe cardiac tamponade. The chi-square test was used to compare proportions, the MannWhitney U-test was applied for comparison of continuous values. Multivariate logistic regression analysis was performed to assess the independent effect of preoperative impending/severe cardiac tamponade on the combined endpoint. Variables with significant collinearity were not entered simultaneously in the same model, but separate models were applied for collinear variables. Results of the logistic regression model were presented as the odds ratio (OR) and the 70% confidence interval (70% CI). The Hosmer Lemeshow test was used to assess the model fit. All P-values are two-tailed, and P<0.05 was considered statistically significant. Calculations were performed using SPSS for Windows (Version 10.0).
| 3. Results |
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Of 28 patients with hemodynamic shock, 19 patients had signs of cardiac tamponade: 12 patients had impending cardiac tamponade with palpable pulses and seven patients had severe cardiac tamponade without palpable pulses as the underlying cause. Another seven patients had a free rupture of the aorta and one patient suffered a myocardial infarction due to dissection over the ostium of the left coronary artery. Patients with signs of severe cardiac tamponade underwent mechanical ventilation significantly more often compared to patients without severe cardiac tamponade (five of seven patients (71%) vs. 19 of 80 patients (24%); P=0.02). Furthermore, cardiopulmonary resuscitation was performed significantly more often in patients with severe cardiac tamponade compared to patients without severe cardiac tamponade (three of seven patients (43%) vs. seven of 80 patients (9%); P=0.03). Isolated thoracic involvement of the dissection was found in 49 patients (56%); in the remaining 38 patients the dissection extended into the abdominal aorta. Pre-existing renal failure was found in six patients (7%).
Baseline data of all 87 patients according to the occurrence of MOF/death are presented in Table 2. Patients who suffered MOF/death more frequently had signs of hemodynamic shock preoperatively and more frequently required mechanical ventilation at the ED. Patients who had to be resuscitated had MOF/death more frequently. Furthermore, patients with adverse outcome had a longer time to surgery.
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| 4. Discussion |
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The combined endpoint MOF and in-hospital death used in our analysis might better characterize outcome in these patients than in-hospital death solely, as several patients suffered postoperative critical illness that resulted in permanent damage of multiple organs. Baseline data in this patient series compare well to the literature regarding age, comorbidities and frequency of cardiac tamponade [4,68,10,11,1923]. These studies were performed to assess the outcome of different surgical approaches for the treatment of aortic dissection, a prognostic value of pericardial effusion or tamponade remained unclear so far [4,7,8,10]. The overall in-hospital mortality rate of 37% in the present study was slightly higher compared to previous observations [6,9,19,21]. In the literature mortality rates reported in patients with type A dissection range from 10 to 33% for elective procedures depending on surgical technique [7,9] up to 3043% for emergency operations [4,20]. However, these studies focused on perioperative mortality rates in patients who were actually treated by surgery. We combined pre-, peri- and postoperative mortality until hospital discharge of unselected ED patients, who were included in the study on an intention to treat basis. The inclusion of patients with preoperative death (n=6, 7%) significantly contributed to the relatively high mortality rate.
Tamponade and/or rupture are one of the most common causes of death in non-operated patients, whereas only 5% of the operated patients died of rupture [24]. In the present analysis, signs of preoperative severe cardiac tamponade without palpable pulses were associated with poor outcome, particularly preoperative death. This finding is supported by several former observations with regard to in-hospital death [4,8,10]. All preoperative deaths in our patients were due to severe cardiac tamponade. We found impending cardiac tamponade in patients with palpable pulses not to be associated with adverse outcome.
The frequency of severe cardiac tamponade was rather low in the present patient series, particularly if compared to the frequency of hemodynamic shock. This may be explained by the relatively frequent occurrence of other severe complications of type A aortic dissection in these patients such as hemothorax due to free rupture. Furthermore, this discrepancy may be due to a partial overlap of the definitions of hemodynamic shock (systolic blood pressure below 90 mmHg) and impending cardiac tamponade (tamponade with palpable pulses).
The fact that severe cardiac tamponade has an adverse effect on preoperative outcome in patients with acute type A aortic dissection is a well-known notion. Similarly, we found that the vast majority of these patients died preoperatively. However, remarkably impending cardiac tamponade with palpable pulses was, per se, not associated with poor pre-, peri- or postoperative outcome in the present patient series. But if systolic blood pressure values deteriorate below 90 mmHg, these patients are at higher risk for poor outcome.
Our findings suggest that patients with type A aortic dissection and severe cardiac tamponade are at high risk for preoperative death, even when aggressive treatment with pericardiocentesis or surgical drainage is initiated. Therefore, timely diagnosis and immediate surgery are mandatory. Immediate surgery may avert progression to severe cardiac tamponade and hemodynamic deterioration. Similarly others found that early diagnosis and early treatment of acute aortic dissection before development of cardiac tamponade improved the operative salvage rate [1,7,8,20].
In conclusion, patients with acute type A aortic dissection and signs of preoperative severe cardiac tamponade without palpable pulses had a 16-fold increased risk for poor outcome, particularly preoperative death. However, impending cardiac tamponade with palpable pulses was not associated with increased frequency of MOF/in-hospital mortality.
| References |
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