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Ann Thorac Surg 2003;75:1165-1170
© 2003 The Society of Thoracic Surgeons
a Department of Thoracic and Cardiovascular Surgery, Johann Wolfgang Goethe University, Frankfurt, Germany
b Department of Anesthesiology, Intensive Care, and Pain Therapy, Johann Wolfgang Goethe University Frankfurt, Frankfurt, Germany
Accepted for publication October 24, 2002.
* Address reprint requests to Dr Aybek, Department of Thoracic and Cardiovascular Surgery, Johann Wolfgang Goethe University Frankfurt, Theodor Stern Kai 7, 60590 Frankfurt, Germany
e-mail: t.aybek{at}em.uni-frankfurt.de
| Abstract |
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METHODS: Thirty-five patients underwent ACAB (group A) with left internal mammary artery to left anterior descending coronary artery grafting using a partial lower ministernotomy (n = 25) or double bypass grafting (n = 9) and even triple vessel coronary artery revascularization (n = 1) through complete median sternotomy. Thirty-four patients (group B), matched for age, sex, and comorbidity with group A, underwent either partial lower ministernotomy (n = 24) or OPCAB by complete sternotomy (n = 10). We recorded clinical outcomes and postoperative visual analog scale pain scores.
RESULTS: In group A, 32 patients remained awake throughout the entire procedure. Three patients required secondary intubation because of incomplete analgesia (n = 1) or pneumothorax (n = 2). Patients in group A had a recovery room stay of 6.0 ± 3.2 hours. In group B, mechanical ventilation was implemented for 4.8 ± 3.1 hours and intensive care unit stay lasted 12 ± 6.8 hours. Group A had no in-hospital deaths, compared with 1 death in the conventional OPCAB group. Each group had 1 patient with graft stenosis detected on the pre-discharge angiogram. Early postoperative pain was significantly less in group A than in group B (visual analog scale of 32 ± 8 compared with 58 ± 11, p < 0.0001).
CONCLUSIONS: The present data demonstrate the feasibility and safety of surgical coronary revascularization without general anesthesia. Continuation of thoracic epidural analgesia provides better pain control and faster mobilization after such procedures. Surprisingly, the ACAB procedure was well accepted by the patients.
| Introduction |
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Thoracic epidural anesthesia (TEA) provides excellent perioperative pain management and favorable conditions for off-pump coronary artery bypass surgery by dilating the coronary arteries and the internal thoracic artery (ITA) and by reducing heart rate and arrhythmias during manipulation of the heart [11, 12]. Thoracic epidural anesthesia improves postoperative outcome and accelerates recovery [1315]. Combining off-pump coronary artery bypass grafting (OPCAB) with TEA seems advantageous, as the combination would enable surgeons to carry out coronary artery bypass surgery in the awake patient.
Awake coronary artery bypass (ACAB) through a left anterior small thoracotomy was first reported by Karagoz and colleagues [16]. To evaluate clinical outcome of the new technique, we compared standard OPCAB and minimally invasive direct coronary artery bypass grafting (MIDCABG) procedures with ACAB.
| Patients and methods |
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In group B (n = 34) MIDCABG was performed in 24 patients through partial lower sternotomy and 10 patients had various OPCAB procedures through complete median sternotomy. All patients in group B had conventional general anesthesia and early extubation after the operation. Demographic data and preoperative status of all patients are provided in Table 1.
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To ensure equivalency between both groups, patients had to be appropriate candidates for either procedure to be included in this prospective study. Individuals were selected for each group by the surgeon, in consultation with the patient. Written informed consent was obtained from all patients. The study was approved by the local ethics committee.
Activities of daily living were assessed to evaluate the patients grade of mobilization on the day of surgery [18]. Postoperative pain perception was assessed by the patients themselves using visual analog scale (VAS) on the second and third day after the operation [19].
All data were reviewed prospectively. Data are expressed as mean ± standard deviation. Continuous clinical data were compared by t test and categorical variables were compared using the Mann-Whitney U test. The tests were carried out using the Stat View statistical software package 5.0.1 (Abacus Concepts, Inc, Cary, NC).
Anesthesia for awake coronary artery bypass
High TEA was used in group A only. The objective of this approach was to achieve somatosensory and motor block at the T1 to T8 level. The maximum permissible block level was C6, which was monitored by the development of Horners syndrome. One of the major objectives was to achieve motor block of the intercostal muscles while preserving diaphragmatic respiration.
Antiplatelet therapy was stopped 5 days before surgery in all cases. One day before elective surgery a thoracic epidural catheter (20 G; B. Braun Melsungen AG, Melsungen, Germany) was inserted at the T2-T3 level. On the day of surgery patients were premedicated orally with 7.5 mg midazolam (Hoffmann-LA Roche AG, Grenzach-Wyhlen, Germany). In the operating room patients received an infusion of ropivacaine 0.5% (Astra Zeneca, Wedel, Germany) with sufentanil 1.66 µg/mL (Janssen Cilag, Neuss, Germany) into the epidural space. Sensory level was tested every 5 minutes. Thus sensory block was achieved between the neck and the abdomen, including both arms. Patients breathed O2 at 5 L/min through a facemask. Monitoring included arterial and central venous blood pressure, electrocardiogram (ECG) (II, aVF, V5), pulse oximetry, and end-tidal CO2 (Hellige Marquette Solar 8000 Patient Monitor, Marquette Medical Systems, Milwaukee, WI). Patients received no sedative medication or intravenous analgesic agents during the procedure. After wound closure, the anesthetic regimen was changed to ropivacaine 0.16% and sufentanil 1 µg/mL at 2 to 5 mL/h to provide postoperative analgesia. The thoracic epidural catheter was used for postoperative pain management for as long as 3 days.
Group B received general anesthesia with intravenous propofol (Astra Zeneca, Wedel, Germany), sufentanil (Janssen Cilag), and cisatracurium (GlaxoSmithKline, Munich, Germany). Patients underwent standard monitoring perioperatively and were extubated in the early postoperative period. Criteria for extubation were a normothermic patient, stable hemodynamic and respiratory conditions, and an unremarkable neurologic examination. Pain relief was provided with intravenous Dipidolor (Janssen Cilag) or diclofenac suppositories (Novartis Pharma, Nürnberg, Germany). The amount of analgesic medication in both groups is listed in Table 2.
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| Results |
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Clinical outcome variables
Perioperative ECG monitoring with automatic ST-segment analysis displayed no signs of myocardial ischemia within the first 6 and 24 hours in group A. Four of 5 patients in group B with unstable angina showed slightly anterior ischemia signs during the surgical procedure; after emergency revascularization within the first 6 hours postoperatively, no further ECG changes were detectable in these patients. In group B the duration of mechanical ventilation was 4.8 ± 3.1 hours. The duration of postoperative monitoring phase in the recovery room was 6.0 ± 3.2 hours (group A). In group B intensive care unit stay was 12 ± 6.8 hours. Patients remained hospitalized for 7.4 ± 2.1 days in group A compared with 8.3 ± 1.3 days in group B (Table 2).
Mortality and morbidity
There was one early death in group B. This patient died from severe respiratory failure and sepsis following long-term ventilation. No patient suffered spinal complications caused by placement of the epidural catheter. Transient Horners syndrome was observed in 2 group A patients.
Need for analgesia and visual analog scale pain scoring
Because of continuous analgesic drug application through the epidural catheter for 3 postoperative days, pain perception was significantly lower in group A (VAS = 32 ± 8 in group A compared with 58 ± 11 in group B, p < 0.0001). Effective pain management resulted in faster postoperative mobilization in group A (see Table 2).
Coronary angiography
Quality of anastomoses were examined in all patients. Twenty-eight patients in group A underwent coronary angiography before discharge. In 7 patients multidetector computer tomography (MDCT) was performed to check graft patency. All grafts showed good function except for one proximal ITA occlusion in group A. Twenty-eight patients in group B had control angiography and 6 patients underwent MDCT to verify graft patency. In group B 1 patient had an ITA stenosis at the anastomotic site.
| Comment |
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We used partial lower ministernotomy to access the ITA and the heart. This surgical approach provides extrapleural access to the target structures, to avoid impairment of spontaneous respiration during surgery. Furthermore, a conversion to full sternotomy, which was not required in this study, is much easier than in a left anterior small thoracotomy (LAST) approach. The entry into the chest cavity by the LAST approach constitutes a compromise between ITA dissection and access to the LAD. The technique usually exposes only a few segments of the LAD, whereas in the partial lower ministernotomy technique the whole length of the vessel is exposed. Moreover, LAST inevitably causes pneumothorax, which impairs spontaneous breathing. Complete median sternotomy with the avoidance of general anesthesia and positive pressure ventilation for CABG has not been described yet in literature. This standard approach in heart surgery allows ideal access to all regions of the heart and multi-vessel revascularization. In these patients double or triple bypass grafting was performed using arterial grafts while the patients were conscious, whereas in this initial series only the anterior wall of the heart was revascularized.
The awake status of the patient provides an important advantage in beating heart procedures. During stabilization, the systemic blood pressure may drop to a critical level. In patients who have undergone general anesthesia, this level remains unknown (usually a blood pressure of at least 80 mm Hg is considered mandatory). In awake patients we have the best type of monitoring, namely neurologic vigilance.
Another advantage is that the potential risks of endotracheal intubation, such as trauma to teeth or vocal cords or peri-intubational hypoxia, are avoided. Some patients experience hemodynamic compromise related to narcotic medication before intubation, which carries the risk of preoperative myocardial ischemia or infarction in patients with severe coronary artery disease [9, 10, 20, 21]. Patients with certain risk profiles including chronic obstructive lung disease, coagulation disorders, and neurologic conditions appear to derive the most benefit from operations without cardiopulmonary bypass [11]. However, major complications after CABG surgery are often associated with preexisting pulmonary disease or reduced general status. This condition often requires prolonged postoperative ventilatory support and prolonged intensive care unit stay. With ACAB the risk of postoperative pulmonary failure and long-term ventilation may be reduced. Therefore we believe that ACAB is a promising adjunct to current minimally invasive CABG techniques. Another impact on the CABG patient population could be a potential use of this procedure in a hybrid technique, which is a coronary revascularization technique using the combination of interventional cardiologic and cardiac surgical methods.
The direct transfer of ACAB patients from the operating room to the recovery room ward is a novelty that has been reported as a fast-track pathway by several groups [24]. In ACAB, however, patients receive no sedative drugs and are thus more vigilant than patients after general anesthesia and early extubation. Compared with sedated patients, ACAB patients in this study had significantly less pain as measured by VAS, showing faster mobilization and even activities of daily living a few hours after surgery. All patients recovered well but remained hospitalized for 7.4 ± 2.1 days because of local reimbursement regulations.
Combining the benefits of beating heart CABG without CPB, a small incision, avoidance of general anesthesia and positive pressure ventilation, and effective pain management, the ACAB technique brings the long-term benefits of surgical revascularization closer to catheter-based interventional technique than any other current minimally invasive approach. Such innovation with excellent patient acceptance and presumably lower costs may lead to a new standard for CABG with the final vision of ambulatory heart surgery.
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