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Ann Thorac Surg 1998;66:785-791
© 1998 The Society of Thoracic Surgeons

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Original articles: Cardiovascular

A dual-vent left heart deairing technique markedly reduces carotid artery microemboli

^a Cardiothoracic Surgical Unit, Green Lane Hospital, Auckland, New Zealand
^b Royal New Zealand Navy Hospital, New Zealand

Accepted for publication April 7, 1998.

Address reprint requests to Dr Milsom, Cardiothoracic Surgical Unit, Green Lane Hospital, Green Lane West, Epsom, Auckland, New Zealand
e-mail: (pagetm{at}ahsl.co.nz)

	Abstract

Top Abstract Introduction Material and methods Results Comment Acknowledgments References

 
Background. Cerebral embolization, mainly bubbles, follows aortic declamping in left heart valve operations. Embolization is not prevented by conventional left heart deairing methods. We have validated a "dual-vent" deairing technique, which uses high-flow left ventricular and aortic venting from the working heart into the cardiopulmonary bypass venous line before aortic declamping.

Methods. After left heart valve replacement, intraoperative color-flow Doppler echocardiography was used to monitor the right common carotid embolic activity in 58 consecutive patients who underwent conventional deairing (group 1), 14 consecutive patients who underwent deairing by the dual-vent technique (group 2), and 4 patients who received nonvented coronary artery bypass grafting who did not require deairing (group 3).

Results. The median emboli count recorded after aortic declamping was 1,647 (range, 342 to 6,852) and 101 (range, 0 to 865) in the group 1 and 2 patients, respectively (p < 0.0001). The efficacy of the dual-vent technique improved throughout the series: in the last 7 patients, the emboli counts often approached the very low levels seen in group 3 patients (median, 8; range, 1 to 16).

Conclusions. Cerebral embolization after aortic declamping in left heart valve operations was significantly reduced by this dual-vent deairing technique.

	Introduction

Top Abstract Introduction Material and methods Results Comment Acknowledgments References

 
Neurocognitive deficits are more common after operations with cardiopulmonary bypass (CPB) than after operations of similar technical complexity and duration that do not involve CPB [1]. Microembolism of the cerebral circulation, by bubbles or particulate matter, is important in the etiology of these deficits [2–4]. Hence minimizing emboli is important [2] in open heart chamber operations, such as aortic and mitral valve operations, in which retained left heart air results in many more cerebral emboli than occur in closed chamber procedures, such as coronary artery bypass grafting (CABG) [5–7]. Methods to improve deairing after open chamber operations have focused mainly on the use of ultrasound imaging devices to guide existing techniques, which include careful filling of the heart to displace air, needle aspiration of the cardiac chambers, and suction venting of the left ventricle and ascending aorta. The free ejection of blood through an aortotomy or atriotomy is sometimes used. Positive-pressure ventilation is commonly used during these maneuvers to mobilize air from the pulmonary veins, while the heart is manipulated to release air from trabeculae and recesses. It is recognized, however, that these techniques are not completely effective [5, 7–11].

We report a technique that allows the heart to eject at near-physiologic output into the cardiopulmonary reservoir while the aortic cross-clamp remains in situ. This is associated with significantly lower right common carotid artery (RCCA) emboli counts after aortic declamping in patients undergoing left heart valve operations.

	Material and methods

Top Abstract Introduction Material and methods Results Comment Acknowledgments References

 
All five surgeons at our hospital have traditionally used conventional deairing techniques. One (F.P.M.) recently developed and now routinely uses a dual-vent technique. The Northern Regional Health Authority Ethics Committee approved the data collection (August 1994) as part of an investigation into neurocognitive function after open heart operations. As a result of this trial, we are able to report an audit of the efficacy of different deairing techniques.

Patient groups
Subjects were patients aged 20 to 73 years who underwent a left heart valve operation between December 1995 and July 1997. Group 1 was a cohort of 58 consecutive patients undergoing conventional deairing by five surgeons. Two subgroups within group 1 were defined: Group 1a was a cohort of 10 consecutive patients operated on by the individual surgeon most successful in conventional deairing (although there was no statistically significant difference between surgeons), and group 1b was a cohort of 16 consecutive patients deaired conventionally by F.P.M. before adoption of the dual-vent technique. Group 2 was a cohort of 14 consecutive patients undergoing deairing by the dual-vent technique. A third group (group 3) of 4 patients undergoing nonvented CABG was also monitored with right common carotid Doppler echography to obtain emboli counts illustrative of closed chamber procedures (a control group).

Conduct of anesthesia and cardiopulmonary bypass: all patients
Anesthesia was conducted according to the individual anesthetist’s normal clinical practice. This was typically based on moderate doses of fentanyl (10 to 50 µg · kg^-1) supplemented as necessary with benzodiazepines, volatile anesthetic agents, and nondepolarizing muscle relaxants. Monitoring was in accordance with the guidelines of the Australian and New Zealand College of Anaesthetists.

All patients underwent hypothermic CPB on an extracorporeal circuit that included a Medtronic Maxima Plus hollow-fiber membrane oxygenator, a Medtronic Maxima adult hard-shell combined venous and cardiotomy reservoir (Medtronic Blood Systems, Anaheim, CA), and a Bentley AF1040D 40-µm screen arterial filter (Baxter Healthcare Corporation, Irvine, CA) with a continuous purge. In preparation, the circuit was CO₂ flushed, primed with Plasmalyte 148 and 0.75 g · kg^-1 mannitol (Baxter Healthcare Corporation), and then recirculated through a 0.2-µm prebypass filter (Pall Biomedical, Fajardo, Puerto Rico) to remove air. An alpha-stat pH management protocol was followed.

The CPB arterial line was introduced into the ascending aorta using a 24F aortic cannula (Sherwood Medical, St Louis, MO). A two-stage atrial cannula (Research Medical, Midvale, UT) was used for CPB venous return. Cardiac arrest was obtained after aortic cross-clamping with blood cardioplegia administered by either or both of the antegrade and retrograde routes. The left heart was vented by a cannula introduced via the right superior pulmonary vein. When an aortic valve operation was undertaken the vent was advanced into the left ventricle.

Right common carotid doppler monitoring
The RCCA was monitored with a Flowlink 300 color-flow Doppler monitor (Rimed, Tel Aviv, Israel). This was interfaced to a purpose-built analog signal processor and an 80C552 digital microcontroller (Mandeno Granville, Auckland, New Zealand), which counted embolic signals. This device and its calibration have been described in detail elsewhere [12]. It was not designed to characterize the emboli according to size or material composition.

The Doppler monitor was operated in the 2 MHz pulsed wave mode. The probe was continuously hand held with beam depth, probe angle, and signal gain adjusted to optimize both the audible flow signal and the color-flow display. A Doppler beam width of 10 mm and machine power of 40% were used for all patients. Artifact signals caused by probe movement were clearly distinguishable from the characteristic chirps and pops of emboli. A control device allowed the Doppler operator to remove the data recorded over the previous 5 seconds if an artifactual signal was identified. As Doppler signal processors may be confounded by many factors [13] and as embolic "counts" are not exact, we refer to the "count" as an "index of microembolic activity" (IMA). Nevertheless, previous calibration of our device has demonstrated that increases in IMA are directly proportional to emboli numbers [12].

All Doppler monitoring was performed by the same operator. Although the operator was not blinded to the nature of the operative procedure or the deairing technique used, there was no subjective grading or counting of embolic signals apart from the occasional recognition and canceling of artifactual counts caused by probe movement.

The operation was divided into eight Doppler monitoring phases (A through H), designed to reflect commonly accepted risk factors for emboli generation as follows:

1. The 5-minute period before placement of the first sutures in preparation for aortic and right atrial cannulation (a stable period in which no emboli were expected).
   
2. The end of A to the beginning of CPB (risk of introducing air or dislodging particulate matter during aortic manipulation and cannulation).
   
3. The first 10 minutes after the beginning of CPB (risk of introducing bubbles from an incompletely deaired CPB circuit).
   
4. The end of C to the beginning of rewarming (a relatively stable period when few emboli were expected).
   
5. Beginning of rewarming to 34°C (risk of bubble generation by reduction of gas solubility during rewarming).
   
6. 34°C to aortic declamping (a relatively stable period when few emboli were expected).
   
7. Aortic declamping until withdrawal of CPB (risk of ejection of retained intracardiac/pulmonary venous air or particulate debris).
   
8. The first 20 minutes after withdrawal of CPB (risk of continued ejection of retained intracardiac/ pulmonary venous air or particulate debris).
   

Conventional deairing: groups 1, 1a, and 1b
Although there were subtle variations in technique between the five surgeons, conventional deairing followed the accepted pattern [14]. Before withdrawal of CPB, the left heart vent was turned off to allow left heart filling and displacement of air out of the atriotomy or aortotomy. Intermittent positive-pressure pulmonary ventilation was used to aid mobilization of pulmonary venous air. Manipulation of the heart promoted air into the open atriotomy or aortotomy, which was then closed. The left heart chambers were aspirated with a needle and syringe. The heart was defibrillated if necessary, and the left heart was vented actively (suction) or passively into the pericardium. Before aortic declamping, the left heart vent was removed, and the aortic root was vented actively into the CPB reservoir or passively into the pericardium. No echocardiographic guidance of deairing was employed. Two surgeons routinely placed the patient in a head-down position during these maneuvers, whereas 3 did not.

Dual-vent deairing: group 2
The dual-vent deairing technique was designed to establish near-normal cardiac output from the working heart, and therefore near-normal pulmonary blood flow, while keeping the aortic clamp in place and routing the ejected arterial blood back into the CPB circuit. This was achieved as follows: Preparation of the CPB circuit, conduct of anesthesia, and the initial establishment of CPB were as described above, except that the cardioplegic line was connected into a 21F Argyle cannula (Sherwood Medical, St. Louis, MO) placed proximal to the aortic clamp. This cannula would later function as the aortic vent (see below). A 17F Research Medical vent/catheter was positioned through the right superior pulmonary vein into the left heart chambers. A -inch Y connector was placed in the CPB venous line.

On completion of the valve operation, the left heart vent was advanced into the ventricle. The aortic and left heart vents were connected into the venous line (Fig 1) by -inch tubing and appropriate connectors to allow potentially unrestricted drainage of blood and emboli from this dual-vent system into the CPB reservoir. A variable flow restrictor ("variable resistor"), initially closed, was positioned as shown to maintain a high-pressure and a low-pressure side in the circuit.

View larger version (31K): [in this window] [in a new window]   Fig 1. Schematic layout of the dual-vent deairing apparatus (see text for details). (CPB = cardiopulmonary bypass; LV = left ventricle; RA = right atrium; SVC = superior vena cava.)

During cardiac recovery with the left ventricular vent in situ, the atrial pressures were elevated to obtain a working heart. Positive-pressure ventilation was commenced. Aortic root pressures were a function of inflow from both the cardioplegia line and the left ventricle, and resistance to outflow into the coronary circulation and the aortic vent, the latter being controlled by the variable resistor.

After cardiac recovery, the left ventricular vent was removed. The working heart continued to eject into the venous line via the aortic vent. The variable resistor, cardioplegia line blood flow rate, and atrial pressures were adjusted to maximize cardiac output while maintaining appropriate aortic root pressures (120 mm Hg systolic and 30 to 40 mm Hg diastolic). Insufficient resistance would cause aortic root pressure to fall with a consequent reduction in myocardial perfusion. Excessive aortic root pressure was avoided by left heart venting (while this vent was in place), attention to atrial loading conditions, and adjustment of the variable resistor.

Immediately before aortic declamping, the systolic pressure in the aortic root was reduced below mean systemic perfusion pressure by cessation of blood inflow into the cardioplegic line, wide opening of the variable resistor, and reduction of atrial filling pressure. The aorta was declamped and CPB was then withdrawn.

Nonvented patients undergoing coronary artery bypass grafting: group 3
Four consecutive patients undergoing CABG without venting of the left ventricle underwent RCCA monitoring after removal of the cross-clamp.

Myocardial damage
Group 2 patients had their preoperative and postoperative electrocardiograms examined by an independent cardiologist for evidence of Q-wave infarction. Serum was collected on the day after the operation for evaluation of the serum aspartate aminotransferase (AST) level as an index of myocardial infarction [15].

Statistics
Nonparametric analysis was performed as embolic activity was not normally distributed. Data were expressed as median value with ranges. Group comparisons were made using a Mann-Whitney U test for continuous variables and a ² test for categoric variables. A p value less than 0.05 was taken to indicate statistically significant trends.

	Results

Top Abstract Introduction Material and methods Results Comment Acknowledgments References

 
Group characteristics
Relevant medical and surgical data for groups 1, 1a, 1b, and 2 are shown in Table 1. The groups are essentially similar, showing no statistically significant differences except for the duration of both CPB and cross-clamping in the group 1a patients (p < 0.01 and p < 0.025, respectively). It is of note that there was no significant difference between the groups with respect to time spent deairing (defined as the period between reaching 34°C during rewarming and withdrawal of CPB). In addition to the data presented in Table 1, there was no significant difference between the groups with respect to the number undergoing reoperations, or combined valve replacement and CABG procedures.

View larger version (11K): [in this window] [in a new window]   Fig 2. Index of microembolic activity (IMA) during each phase of the operation in group 1. (A = 5-minute period before placement of the first sutures; B = end of A to the beginning of cardiopulmonary bypass [CPB]; C = 10 minutes following the beginning of CPB; D = from C to the beginning of rewarming; E = beginning of rewarming to 34°C; F = 34°C to aortic declamping; G = aortic declamping until withdrawal of CPB; H = 20 minutes after CPB withdrawal.)

Highly variable levels of RCCA embolic activity (IMA of 0 to 5,480) were recorded during the relatively long period of stable CPB (phase D) before rewarming. Removal of the aortic cross-clamp (phase G) was usually marked by a shower of RCCA emboli. Greater embolic activity invariably occurred with weaning from CPB and commencement of left heart ejection. This activity persisted for variable periods in phase H, but only rarely were emboli detected after 20 minutes.

Comparison of deairing efficacy in group 1 and group 2
Figure 3 shows the range and median IMA recorded after aortic declamping for all patient groups. The IMA recorded after aortic declamping in group 2 patients was significantly lower than that recorded in any of groups 1, 1a, or 1b (p < 0.0001). Table 2 reports the group 2 patients in chronologic order. The efficacy of the dual-vent technique improved through the series, with 7 of the last 10 patients being exposed to embolic activity similar to that seen after aortic declamping in the group 3 patients. Table 3 reports the IMA after declamping in group 1 patients stratified according to selected surgical or patient variables. None of these variables appeared to significantly influence the IMA after declamping, although there were trends toward a decreased incidence of cerebral emboli associated with aortic valve replacement, nonredo procedures, and valve replacement with concomitant CABG (see Table 3). If group 1 is stratified to include only those patients receiving these "favorable" procedures (n = 12) then the median IMA after declamping would be 977 (range, 342 to 5,008). However, even this "favorable" subgroup is still exposed to significantly more emboli than group 2 (p < 0.0005).

View larger version (10K): [in this window] [in a new window]   Fig 3. Index of mircroembolic activity (IMA) recorded after aortic declamping in all groups. (group 1 = conventional deairing; group 1a = surgeon conventional deairing with lowest median IMA; group 1b = F.P.M. conventional deairing; group 2 = dual-vent technique; group 3 = nonvented coronary artery bypass grafting.)

	Comment

Top Abstract Introduction Material and methods Results Comment Acknowledgments References

 
Distribution of right common carotid artery emboli during left heart valve operations
Both the number and temporal distribution of emboli recorded in the patients deaired conventionally were similar to those reported by other authors [6, 8]. In particular, the overwhelming numeric importance of emboli appearing after aortic declamping (see Fig 2) was also reported by Van der Linden and Casimir-Ahn [8], and this emphasizes the urgent need for superior deairing methods [5, 10, 16].

We recorded several sources of emboli during stable CPB (phases D through F) that have received little attention in the recent literature. First, there was an apparent relationship between RCCA emboli activity and low venous reservoir blood volume. If the volume fell below approximately 700 mL (manufacturer’s recommended minimum, 300 mL), RCCA microemboli were detected, with the IMA increasing at rates up to 10 per minute. In vitro experiments that confirm our observation have been reported [12]. Second, despite an initial belief that venous air would be removed by the various components of the CPB circuit, the appearance of visible bubbles in the venous line invariably resulted in the detection of microemboli in the RCCA, with the IMA incrementing at rates up to 109 per minute. This resulted in the very high IMA of 5,480 recorded during phase D in 1 patient. Clearly, the venous reservoir and arterial line filter cannot be relied upon to remove all venous air. No generation of bubbles was observed during rewarming [17], because steep rewarming gradients (>10°C) were avoided in accordance with current recommendations [13].

Significance of the deairing technique
Stroke and neurocognitive deficit are recognized complications of both CABG and valve operations. Embolism of the cerebral circulation is proposed as an important contributing factor [7], and three studies do report a correlation between deterioration in postoperative neurocognitive performance and emboli exposure in CABG patients [18–20]. Patients undergoing valve operations are exposed to more emboli than CABG patients [6] and appear to be at a higher risk of neurologic complications [21]. Therefore, vigorous attempts to minimize embolization are appropriate.

This study and others [5, 8, 11, 16] demonstrate that conventional deairing methods lack efficacy, and that there is significant potential for reduction of cerebral embolism by improvement of cardiac deairing [8]. Deairing failure is now better understood through the use of transesophageal echocardiography. Pockets of air "trap" in sites such as the left ventricular apex, left atrial appendage, and right coronary sinus [16], and especially in the pulmonary veins [5, 16], from which air is particularly difficult to remove [5]. Tingleff and colleagues [5] observed bubbles emerging from the pulmonary veins intermittently for up to 28 minutes after withdrawal of CPB, and observed that pulmonary venous air is only mobilized when flow through the pulmonary circulation approaches physiologic levels. In conventional deairing this is only achieved after the aorta is declamped, at which stage any bubbles emerging from the pulmonary veins are ejected into the systemic circulation. Attempts to trap bubbles by partially clamping the aortic root and venting proximal to the clamp are largely ineffective because gaseous microemboli will be distributed with flow and influenced minimally by buoyancy.

Attempts to improve conventional deairing methods have been reported in which transesophageal echocardiography [9, 11] or transesophageal echocardiography and Doppler monitoring of the left ventricular vent [10] are used to guide the process. Although some advantage is apparent, especially for transesophageal echocardiography and Doppler monitoring of the left ventricular vent [10], conventional techniques fail because of their inherent inefficiency at eradicating pulmonary venous air. Moreover, transesophageal echocardiography is cumbersome and expensive [10] in terms of both equipment and operator time, and it also carries a small risk of esophageal trauma [9]. Other authors have advocated intraoperative two-dimensional echocardiography to assist with needle aspiration of air in the heart chambers [22], a purpose-built needle aspirating device [23] to replace the traditional syringe and needle, and the measurement of end-tidal CO₂ to assess pulmonary blood flow during deairing maneuvers [24]. However, no data have been presented to establish the efficacy of these strategies.

In our technique the left ventricular vent extracts emboli to the venous reservoir in the early phase of cardiac recovery. As the myocardium recovers, the aortic vent allows near-physiologic cardiac output from the working heart, which achieves "flushing" of the pulmonary veins. Vigorous cardiac activity also maximizes the likelihood that bubbles and particulate matter will be mobilized from trabeculations on the heart chamber walls. Because the aorta remains clamped, air and any particulate matter flushed from the heart and pulmonary veins pass to the CPB circuit rather than into the systemic circulation.

We continuously monitored RCCA embolic activity from aortic declamping to well after weaning from bypass, to demonstrate complete or near-complete left heart and pulmonary vein deairing by the dual-vent technique. Our data suggest that the dual-vent technique (group 2) is significantly more effective than conventional deairing (group 1). The difference in emboli exposure remains significant when group 2 is compared with patients deaired by the individual surgeon most successfully applying conventional deairing (group 1a), and with patients previously deaired conventionally by F.P.M. (group 1b). No confounding variables were identified that could explain the difference in IMA recordings (see Table 1). Moreover, none of these variables significantly influenced the IMA after declamping in patients deaired conventionally (see Table 3). Finally, even if group 1 is stratified to include only those patients with the most favorable of these characteristics, this group is still exposed to significantly more emboli than group 2.

Other than the minor inconvenience of adapting to a different technical procedure, use of the dual-vent circuit is not associated with any particular problems. The most demanding aspect is the control of aortic root pressure with the variable resistor. We are currently attempting to simplify the use of the circuit by automating this device. Concerns that leaving the clamp in situ while the heart works might increase coronary artery embolism seem unfounded given that aortic root pressures are maintained at physiologic levels throughout the procedure. None of the patients deaired by the dual-vent technique in this study showed evidence of Q-wave infarction or elevation of the serum level of aspartate aminotransferase. Moreover, there has been no increase in the rate of myocardial complications in a much larger series of patients who were not part of this study. We are continuing to rigorously evaluate myocardial preservation, and are gathering data on neurocognitive outcomes.

Within the constraints imposed by small patient numbers, the results presented here show a striking reduction in emboli exposure associated with the use of this dual-vent deairing technique. This reduction in emboli, after aortic declamping, cannot be ascribed to any other confounding factor examined.

	Acknowledgments

Top Abstract Introduction Material and methods Results Comment Acknowledgments References

 
We thank Sir Brian Barratt-Boyes, Dr Athol Wells, and Dr Alan Merry for their significant input, Dr Des Gorman for his constructive critique, and Mrs Sylvia Chan Ng for her secretarial skill. This work was supported by grants from the English Freemasons of New Zealand and the Health Research Council of New Zealand.

	References

Top Abstract Introduction Material and methods Results Comment Acknowledgments References

 

1. Shaw P.J., Bates D., Cartlidge N.E.F., et al. Neurologic and neuropsychological morbidity following major surgery: comparison of coronary artery bypass and peripheral vascular surgery. Stroke 1987;18:700-706.[Abstract/Free Full Text]
2. Treasure T. Interventions to reduce cerebral injury during cardiac surgery—the effect of arterial line filtration. Perfusion 1989;4:147-152.[Free Full Text]
3. Mills S.A. Risk factors for cerebral injury and cardiac surgery. Ann Thorac Surg 1995;59:1296-1299.[Abstract/Free Full Text]
4. Stump D.A., Roger A.T., Hammon J.W., Newman S.P. Cerebral emboli and cognitive outcome after cardiac surgery. J Cardiothorac Vasc Anesth 1996;10:113-119.[Medline]
5. Tingleff J., Joyce F.S., Pettersson G. Intraoperative echocardiographic study of air embolism during cardiac operations. Ann Thorac Surg 1995;60:673-677.[Abstract/Free Full Text]
6. Stump D.A., Stein C.S., Tegeler C.H., et al. Validity and reliability of an ultrasound device for detecting carotid emboli. J Neuroimag 1991;1:18-22.[Medline]
7. Ohnishi Y., Uchida O., Hayashi Y., Kuro M., Sugimoto K., Kuriyama Y. Relationship between retained microbubbles and neurophychologic alterations after cardiac operation. Masui 1995;44:1327-1333.[Medline]
8. Van der Linden J., Casimir-Ahn H. When do cerebral emboli appear during open heart operations? A transcranial Doppler study. Ann Thorac Surg 1991;51:237-241.[Abstract/Free Full Text]
9. Oka Y., Inoue T., Hong Y., Sisto D.A., Strom J.A., Frater R.W. Retained intracardiac air—transesophageal echocardiography for definition of incidence and monitoring removal by improved techniques. J Thorac Cardiovasc Surg 1986;91:329-338.[Abstract]
10. Rescigno G., Riom H., Hallali P., Nottin R., Arnaud-Crozat E. Doppler analysis of the left venting line: an effective and simple technique to control heart de-airing. Cardiovasc Surg 1995;3:65-69.[Medline]
11. Dalmas J.-P., Eker A., Girard C., et al. Intracardiac air clearing in valvular surgery guided by transesophageal echocardiography. J Heart Valve Dis 1996;5:553-557.[Medline]
12. Mitchell S.J., Willcox T., McDougall C., Gorman D.F. Emboli generation by the Medtronic Maxima hard-shell adult venous reservoir in cardiopulmonary bypass circuits: a preliminary report. Perfusion 1996;11:145-155.[Abstract/Free Full Text]
13. Kurusz M., Butler B.D. Embolic events and cardiopulmonary bypass. In: Gravlee G.P., Davis R.F., Utley J.R., eds. Cardiopulmonary bypass: principles and practice. Baltimore: Williams and Wilkins, 1993:267-281.
14. Kirklin J.W., Barratt-Boyes B.G. Cardiac surgery, 1st ed. New York: J Wiley and Sons, 1986:66-67.
15. Merry A.F., Ramage M.C., Whitlock R.M., et al. First-time coronary artery bypass grafting: the anaesthetist as a risk factor. Br J Anaesth 1992;68(1):6-12.[Abstract/Free Full Text]
16. Orihashi K., Matsuura Y., Hamanaka Y., et al. Retained intracardiac air in open heart operations examined by transesophageal echocardiography. Ann Thorac Surg 1993;55:1467-1471.[Abstract/Free Full Text]
17. Govier A. Central nervous system complications after cardiopulmonary bypass. In: Tinker J.H., ed. Cardiopulmonary bypass: current concepts and controversies. Philadelphia: Saunders, 1989:41-61.
18. Stump D.A., Tegeler C.H., Rogers A.T., et al. Neuropsychological deficits are associated with the number of emboli detected during cardiac surgery. Stroke 1993;24:509.
19. Pugsley W., Klinger L., Paschalis C., Treasure T., Harrison M., Newman S. The impact of microemboli during cardiopulmonary bypass on neuropsychological functioning. Stroke 1994;25:1393-1399.[Abstract/Free Full Text]
20. Clark R.E., Brillman J., Davis D.A., Lovell M.R., Price T.R.P., Magovern G.J. Microemboli during coronary bypass grafting—genesis and effect on outcome. J Thorac Cardiovasc Surg 1995;109:249-258.[Abstract/Free Full Text]
21. Nussmeier N. Adverse neurologic events: risks of intracardiac vs extracardiac surgery. J Cardiothorac Vasc Anesth 1996;10:31-37.[Medline]
22. Diehl J.T., Ramos D., Dougherty F., Pandian N.G., Payne D.D., Cleveland R.J. Intraoperative, two dimensional echocardiography-guided removal of retained intracardiac air. Ann Thorac Surg 1987;43:674-675.[Abstract/Free Full Text]
23. Zhong B.-T. A new device for evacuating air from the cardiac chambers. Tex Heart Inst J 1993;20:235-237.[Medline]
24. Hoka S., Okamoto H., Takahashi S., Yasui H. Adequate de-airing during cardiac surgery. J Cardiovasc Surg 1995;36:201-202.[Medline]

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