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Ann Thorac Surg 2005;80:934-938
© 2005 The Society of Thoracic Surgeons
a Department of Cardiovascular Medicine, Division of Cardiac Surgery, Catholic University, Rome, Italy
b Department of Cardiovascular Sciences, Units of Cardiac Surgery, University Campus Bio-Medico of Rome, Rome, Italy
Accepted for publication January 17, 2005.
* Address reprint requests to Dr Anselmi, Department of Cardiovascular Sciences, Unit of Cardiac Surgery, Campus Bio-Medico University of Rome, Via Longoni 83, 00155 Rome, Italy (Email: amedeo.anselmi{at}aliceposta.it).
| Abstract |
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METHODS: Ninety-six redo cardiac surgery patients were operated on with the use of harmonic scalpel, and 105 redo patients operated on by traditional electrocautery and scissors were selected from our database and served as controls. Intraoperative and postoperative data of the two groups were collected and compared. Univariate and multiple logistic regression analyses were performed for identification of factors associated with death and with major and minor complications in the overall study population and in both groups, separately.
RESULTS: Although mortality and major postoperative morbidity were comparable in the two groups, harmonic scalpel patients presented markedly reduced postoperative bleeding, lower incidence of minor complications, cardiac injuries, major arrhythmias, and need for transfusions. Operative time and mean intensive care unit stay were shorter. Use of ultrascissor was found to be a protective factor against minor morbidity at multivariate analysis.
CONCLUSIONS: Our data suggest that harmonic scalpel is safe and is associated with better in-hospital outcome and lower postoperative blood loss in redo cardiac surgery.
| Introduction |
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The harmonic scalpel, HS (Ultracision, Ethicon, Cardiovations, Italy), was initially introduced in clinical practice with the aim of reducing tissue trauma, facilitating dissection, and improving surgical hemostasis. In animal experiments it has proven to incise with minimal heat conduction and to heal without leaving massive fibrosis [10]. The HS uses ultrasonic energy to achieve simultaneous cutting and coagulation and to minimize lateral thermal damage. Until now, it has been used mainly for harvesting arterial conduits for coronary artery bypass grafting [1113], and only seldomly has it been used in redo procedures. In contrast to traditional electrocautery, the HS is also likely to avoid risks of damage to the pulse generator of an implanted pacemaker, inhibiting or triggering in demand modes during surgery [14]. With respect to redo cardiac procedures, the HS has been suggested to decrease intraoperative and postoperative heart rhythm disturbances [15]. However, there are no exhaustive data in the literature about the impact of routine use of the HS in redo cardiac patients.
Therefore, in the present study we sought to evaluate the safety and usefulness of the HS in redo cardiac procedures performed at our institution and the effects of its adoption on in-hospital clinical outcome.
| Patients and Methods |
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As the effects of HS on bleeding is a major focus point of the present study, exclusion criteria consisted of the following:
The same exclusion criteria were applied to non-HS individuals. Ninety-six patients were operated on using the HS, and 105 further cases were selected in which the conventional electrocautery and scissors had been adopted during the same period (nonharmonic scalpel, NHS). The adoption of HS was decided in each case according to the surgeons preference. The main preoperative features of patients groups are presented in Table 1.
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Anesthesia Protocol and Operative Technique
Computed tomographic scan was preoperatively performed in event of tricuspid valve disease or history of aortic surgery. Anesthesia was induced by thiopental sulphate (2 to 3 mg/kg) and sufentanil (0.5 µg/kg), and muscle relaxation was achieved through pancuronium bromide (0.1 mg/kg). Anesthesia was maintained by isoflurane or sevoflurane and sufentanil (25-µg boluses up to a maximum of 7 µg/kg). As a slight modification to the standard protocol of our institution, for redo procedures tranexamic acid high-dose infusion (loading dose 20 mg/kg followed by infusion at 2 mg/kg per hour) was started after induction.
Antiplatelet therapy for patients affected by coronary artery disease had been suspended at least 6 days before surgery. Operative risk was standardized through the EuroSCORE system [16]. All resternotomies were performed by the same surgical team in a standardized fashion in terms of cannulation and CPB strategies. The sternum was opened using an oscillating saw, careful pericardial adhesion removal was carried out by the ultrascissor among the HS patients, and by traditional electrocautery (Force FX; Valleylab, Boulder, CO) and scissors in the NHS individuals, and final hemostasis was performed with the same methods for the two groups. Heparin-coated CPB circuit was never used. Data about occurrence of ventricular tachycardia, atrial or ventricular fibrillation, and ventricular extrasystoles (major arrhythmias) during cardiac isolation were carefully recorded by the anesthesiology team. For mitral valve surgery, aortic-bicaval cannulation with left upper pulmonary vein venting was adopted, after using a superior septal approach. For isolated aortic valve surgery, we used ascending aorta-right atrial cannulation, and the valve was exposed through a transverse incision. Postoperative bleeding was defined as the chest tube output during the first 24 postoperative hours, and was indexed for body surface area. No patient carried an implanted pacemaker at the time of surgery. Finally, major and minor postoperative complications were defined as onset of any condition listed in the Appendix.
No major changes in intraoperative and postoperative protocols were introduced during the mentioned period.
Statistical Methods
All data were included and processed by an electronic database. All patients operated on during the study period and meeting inclusion criteria were subjected to logistic regression to model the probability of being assigned to the HS or the NHS group, with respect to baseline features, and the propensity score was calculated for each of them. For every HS patient, matching patients with the closest score were selected from the larger pool of NHS patients (overall, 96 and 105 individuals; maximum allowable difference, 0.1). Twenty-one HS patients were excluded because no matching patient could be found in the NHS group. Morbidity was defined as occurrence of major or minor complications (as listed in the Appendix). A two-step multiple logistic regression model was performed for minor complication as the response variable for the overall study population and in both HS and NHS groups, independently. Validation of the models coefficient and predictivity was performed by a jackknife procedure.
Analysis was conducted by the Statistical Package for Social Science software (SPSS, Chicago, IL) and by the SAS software release for propensity scoring analysis (SAS/STAT version 8; SAS Inc).
| Results |
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| Comment |
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The HS has been recently introduced in the cardiac surgery practice for the harvesting of arterial conduits [1113] for coronary artery bypass grafting. It minimizes surgical trauma, improves hemostasis, and facilitates dissection even in complex anatomic settings; mechanical cutting mode (longitudinal oscillations of the device tip at 55.5 MHz) is of particular efficacy in incising protein-rich tissues (ie, fibrous tissue) as it induces rupture of hydrogen bonds and structural denaturation. Smaller vessels are compressed and sealed by a protein clot, whereas a secondary heat generation (cavitation effect) achieves hemostasis of larger vessels. Lamm and colleagues [15] were the first to repor on the superiority of HS in comparison with conventional electrocautery for removal of pericardial adhesions and avoiding interference with heart rhythm. In this randomized study including 20 redo patients, no intraoperative dysrythmias occurred in the HS group, whereas multiple supraventricular and ventricular extrasystoles occurred during redo performed by traditional electrocautery. This is consistent with our findings; major arrhythmias were common in the NHS series and disappeared in the HS group (p = 0.006; odds ratio, 0.0; 95% confidence interval, 0.0 to 0.63). Therefore, rapid onset of CPB was never required among HS patients. All cases of iatrogenic damages to cardiac structures during the procedure were observed among NHS patients, although this difference only approached significance (two-tailed p = 0.11; uncorrected p = 0.042, observed difference, 4 patients; odds ratio, 0.00; 95% confidence interval, 0.00 to 1.51). Nonetheless the occurrence of such injuries during the dissection rather than during the resternotomy phase corroborates the concept that HS may help in avoiding these kinds of damages.
The main intermediate target of redo cardiac surgery is to achieve operative risk comparable to that of the primary procedure, and the phases of resternotomy and cardiac isolation actually are pivotal in determining the operative time and risks. Effects of HS adoption are evident mainly on the complications related to these steps. In the HS group we have spared about 41 ± 17 minutes before onset of CPB and 21 ± 16 minutes before sternum closure, with notable saving of operative time (p = 0.010). Use of HS reduces microvascular hemorrhages, thus contributing to decreased blood loss and cutting short the dissection and the final hemostasis phases. Sources of bleeding in the HS patients were always macroscopic and could be easily detected by the surgeon. Also, postoperative blood loss was significantly lower among HS individuals, as was the incidence of revision for control of bleeding. These factors may be at the root of the optimal control of minor morbidity and of the shortening of mechanical ventilation time and ICU stay. The feasibility of HS in patients affected by coagulation disorders who require surgery is still to be addressed. These subjects were excluded from the present study; nevertheless the HS should be considered in such clinical settings even at first cardiac procedure.
The HS is an expensive device. Its high cost up to now is not counterbalanced by a demonstration of objective clinical benefits related to its use, probably the main explanation for its limited adoption in cardiac surgery. Even in the absence of a specific economic analysis in our study, presented data clearly suggest that the economic benefits related to the lower morbidity and postoperative course of HS patients outweigh the initial cost of the equipment. This is particularly evident in patients with a history of more than one cardiac intervention. Despite the relatively low number of study individuals, rates of transfusion of any blood product were significantly lower in the HS group. This device may render the use of blood resources more efficient.
In conclusion, the adoption of the HS was associated with significant reduction of operative time and of postoperative bleeding without any adverse effect in a retrospective series of redo cardiac surgery patients. Both these factors likely decreased the incidence of complications and the ICU stay. Therefore we suggest that HS should be considered a mandatory armamentarium in redo cardiac surgery.
| Appendix |
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| References |
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