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Eur J Cardiothorac Surg 2002;21:804-817
© 2002 Elsevier Science NL

Review

Systematic review of beating heart surgery with the Octopus® Tissue Stabilizer

N.A. Scotta, J.L. Knightb, B.P. Bidstrupc, H. Wolfendend, R.N. Linacree, G.J. Madderna,f*

a ASERNIP-S, Royal Australasian College of Surgeons, Box 688 North Adelaide, SA 5006, Australia
b Flinders Medical Centre, Adelaide, SA, Australia
c Department of Surgery, North Queensland Clinical School, Townsville, Qld, Australia
d Department of Cardiothoracic Surgery, Prince of Wales Hospital, Randwick, NSW, Australia
e Hobart Surgical, Hobart, Tas., Australia
f Department of Surgery, University of Adelaide, Queen Elizabeth Hospital, Adelaide, SA, Australia

Received 21 August 2001; received in revised form 15 January 2002; accepted 30 January 2002.

* Corresponding author. Tel.: +61-8-8239-1144; fax: +61-8-8239-1244
e-mail: college.asernip{at}surgeons.org


   Abstract
Top
 Abstract
1. Introduction
 2. Methods
 3. Results
 4. Discussion
 References
 
The safety and efficacy of off-pump coronary artery bypass surgery with the aid of the Octopus® Tissue Stabilizer (Octopus OPCAB), in comparison to conventional on-pump coronary artery bypass surgery (CPB-CABG), was examined by a systematic assessment of the peer-reviewed literature. The limited comparative data suggested that there was no difference in safety outcomes between Octopus OPCAB and CPB-CABG. The paucity of efficacy data reported in the higher level comparative studies meant that it was impossible to assess whether Octopus OPCAB was more efficacious than CPB-CABG. The evidence base for the procedure was deemed inadequate and an audit of the procedure was recommended.

Key Words: Octopus • Beating heart • Tissue stabiliser • Bypass • Surgery • Off-pump


   1. Introduction
Top
 Abstract
 1. Introduction
2. Methods
 3. Results
 4. Discussion
 References
 
Coronary artery bypass graft (CABG) surgery is the current surgical benchmark for coronary revascularisation. Continued pharmacological and mechanical innovation in cardiopulmonary bypass (CPB), together with improved preservation of cardiac function during CABG, have resulted in mortality rates of less than 3% [1,2]. However, of 170 895 CABG-only operations (8% were re-operations) performed in the United States in 1996, only 65.4% of procedures reported no complications [3]. The mortality and significant morbidity of CABG is largely attributed to the use of CPB, global cardiac arrest, hypothermia, median sternotomy and manipulation of the aorta [4,5]. The potential complications of CPB include myocardial infarction, arrythmias, stroke, endothelial dysfunction, neuropsychological disorders, multi-organ failure, great vessel damage, nerve injury, whole-body inflammatory response, wound infection and coagulation disorders [3,6].

1.1. Off pump coronary artery bypass
In an attempt to avoid the deleterious effects of CPB, minimally invasive coronary artery bypass grafting has evolved. This terminology refers to procedures that range from thoracoscopic CABG with CPB (peripheral cannulation) to median sternotomy CABG without CPB, and also includes minimally invasive direct coronary artery bypass (MIDCAB) that is performed without CPB or sternotomy [3]. The postulated benefits of off-pump coronary artery bypass graft surgery (OPCAB) are reduced morbidity, a shorter hospital stay and convalescence period, lower costs, equivalent angiographic quality of the bypasses, event free survival in the 1st year, and increased patient comfort compared to conventional CABG with CPB (CPB-CABG) [3,7,8]. However, proper patient selection and effective epicardial stabilisation appear to be crucial [7].

1.2. The Octopus Tissue Stabilizer®
In 1994, Borst et al. [9] developed the Octopus Tissue Stabilizer® which utilises suction to immobilise the epicardium. In 1995, after numerous pig experiments, Jansen et al. [10] successfully used the Octopus Tissue Stabilizer® (Medtronic Inc., Minneapolis, MN) to perform OPCAB in humans. The Octopus Tissue Stabilizer® consists of two suction paddles that are placed in parallel on either side of the coronary artery. Once a suction pressure of 400 mmHg is reached, the target site is effectively immobilised [10]. The Octopus Tissue Stabilizer® has continued to evolve with further design improvements that include a lower profile device with flexible heads and disposable, transparent paddles that are incorporated into a one-piece system which mounts directly on to the sternal retractor.

The use of mechanical stabilisers in OPCAB is becoming increasingly common. However, a review of the evidence regarding their safety and efficacy has yet to be conducted. Therefore, it was the aim of this review to assess the available literature on OPCAB with the aid of the Octopus Tissue Stabilizer® and compare it, in terms of safety and efficacy, against the current benchmark for surgical revascularisation, CPB-CABG.


   2. Methods
Top
 Abstract
 1. Introduction
 2. Methods
3. Results
 4. Discussion
 References
 
This review is a précis of information obtained during the assessment of OPCAB with the aid of the Octopus Tissue Stabilizer® for the Australian Safety and Efficacy Register of New Interventional Procedures-Surgical (ASERNIP-S).

2.1. Search strategy
Published studies detailing the use of the Octopus Tissue Stabilizer®, in conjunction with OPCAB via full median sternotomy (Octopus OPCAB), and CPB-CABG were identified by searching Medline between 01/1966 and 08/02/2001; Current Contents between weeks 1/1993 and 6/2001; Embase between weeks 1/1974 and 5/2001; and The Cochrane Library (Issue 1, 2001). The search terms used for Octopus OPCAB were ‘octopus and (cardi* or surg* or Utrecht or stabil* or graft*)’. For CPB-CABG, the search strategy was restricted to (publication type=review) and (date=since 1997). The two sets of search terms used were ‘heart surg* and graft*’; and ‘cardiopul* bypass and (triple vessel or triple bypass or CAB* or graft* or open heart or (CABG and outcome*))’. The truncation symbol ‘*’ differs in each database and allows retrieval of all possible suffix variations of a root word. Only English language articles were included for review because the foreign language papers, based on their abstract, did not offer any significantly different or more extensive results to those reported in the English language papers. The bibliographies of all publications included for review were pearled for relevant references that may have been missed in the database search.

2.2. Inclusion criteria
Only full, peer-reviewed randomised-controlled trials, non-randomised comparative studies, case series and case reports were included for review. For Octopus OPCAB, only studies on non-pregnant adult human subjects undergoing treatment for single or multiple vessel coronary artery disease were included. Papers that detailed any other surgical approach, such as thoracotomy, were excluded. In addition, any paper reporting results derived from the pooling of data from different surgical approaches and/or mechanical stabilisers was excluded unless the data subset for the full median sternotomy approach and/or Octopus Tissue Stabilizer® could be separated from the aggregate data.

2.3. Outcome measures and data extraction
Table 1 contains the guidelines used for assessing the level of evidence of the studies. A meta-analysis was not performed because the majority of studies were of poor evidence quality and varied widely in outcome measures and study design. Safety outcomes for Octopus OPCAB were assessed in terms of the common end-points reported for CABG while the postoperative indicators chosen to assess the efficacy of cardiac revascularisation via Octopus OPCAB included graft patency rates, the number of patients free of angina, and the re-intervention rate.


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  		Table 1. Designation of levels of evidence table from the National Health and Medical Research Council [39]

 

   3. Results
Top
 Abstract
 1. Introduction
 2. Methods
 3. Results
4. Discussion
 References
 
3.1. Study methodology appraisal
There were two randomised controlled trials (RCTs) (level II evidence) available for review (Table 2) [11,12]. One of these studies [12] compared Octopus OPCAB with a version of CABG that involved the use of CPB in conjunction with a normothermic beating heart. Since this comparator is not conventional CPB-CABG on an asystolic heart, the data from the CABG arm of the study could not be used because the comparator was, by definition, invalid according to the inclusion criteria for the review. Therefore, for the purposes of this review, the Octopus OPCAB data from this paper only represented case series (level IV) evidence. Similarly, five [6,13–16] of the seven level III-2 studies that compared Octopus OPCAB with techniques using a limited access approach represented, for the purposes of this review, level IV evidence. Two papers [17,18] did not clearly state whether all patients underwent median sternotomy. However, direct communication with the study contributors (P. Burton pers. comm.; M. Tugtekin pers. comm.) clarified this point and the papers were subsequently included for review. Two comparative studies provided a mix of concurrent and historical control data (mixed level III-2/III-3 evidence) [17,19]. In one of these studies [17], the two patient groups were recruited over two distinct 3 month periods but it was not specified whether these patients were operated on concurrently. Of the eight case series studies (level IV evidence) available for review, five were prospective and three [18,20,21] were retrospective.


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  		Table 2. Summary of reviewed studiesa

 
Nierich et al. [16] reported an extension of the original patient pool published by Jansen et al. [10,22] and Nierich et al. [6]. However, since this paper was primarily concerned with reporting haemodynamic outcomes and shared few common endpoints with the earlier group of studies, its data were tabulated separately.

The RCT by Baker et al. [11] represented the highest level of evidence quality of the studies comparing Octopus OPCAB with CPB-CABG. While the two patient groups were appropriately selected and comparable, the study was limited by a lack of blinding of the study participants. In addition, since the method of randomisation was not specified, it was impossible to judge whether this was conducted appropriately. The participation rate of the patients approached to enter the study was also not stated. Thus, it was unclear if any self-selection bias occurred on the part of the patients.

In general, the results of the non-randomised controlled and case series studies were poorly reported with a number of inexplicable data errors, omissions, and contradictions between data presented in different sections of the same article [14,15,18,19,23]. In addition, the value of the data reported by some articles was severely limited by a significant loss to follow-up and a paucity of important information regarding patient co-morbidities and operative status, surgical methodology and/or statistical information, which often rendered the data un-interpretable [14,15,24]. The inconsistent use of median and mean data across the studies made it difficult to compare some numerical patient outcomes because median data does not necessarily approximate the population mean unless the population distribution is symmetrical, which cannot be assumed in this case [25]. The inclusion criteria and outcome measures quoted across the studies were very heterogeneous, and many important outcomes, such as operative mortality, were often not reported. Unfortunately, few of the studies used a standardised risk stratification or symptom staging system to classify the patients in the CPB-CABG and Octopus OPCAB groups. This made it difficult to objectively assess and compare the preoperative and postoperative outcomes of patients, either within or between the studies. All of these factors, in conjunction with many methodological weaknesses, made the results very difficult to appraise with any confidence. Nonetheless, some of these results can still be used to gain an insight into the possible safety and efficacy issues relating to Octopus OPCAB.

3.2. Safety of Octopus OPCAB
Tables 3 and 4 summarise the safety outcomes for Octopus OPCAB from the comparative and case series studies.


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  		Table 3. Comparative study safety results for OPCAB with the Octopus Tissue Stabilizer®a

 

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  		Table 4. Safety results for OPCAB with the Octopus Tissue Stabilizer® – level IV evidencea

 
In one study, the incidence of new onset atrial fibrillation was much higher in the Octopus OPCAB group, compared to CPB-CABG, while the converse was true for cerebrovascular accidents, renal failure and death [19]. However, the RCT by Baker et al. [11] demonstrated that the incidence of neuropsychological deficits following Octopus OPCAB and CPB-CABG was similar at both 7 days and 6 months postoperatively for patients undergoing an equivalent number of grafts.

In contrast to the comparative studies, the reporting of safety outcomes in the case series studies was more detailed. Overall mortality ranged from 2.3 to 12.5% in six studies but many of these deaths occurred in patients who had significant preoperative comorbidity. Thus, in many cases, it was unclear how, or if, the surgical intervention had a direct causal link with patient mortality.

Three case series papers [13,15,18] observed low cardiac output syndrome in patients following the Octopus OPCAB procedure but the incidences reported by two [13,18] of the studies appeared to include the same patient who had impaired left ventricular function preoperatively. The study by Pym [15] also included both elective and urgent patients, in addition to some patients with severe aortic or carotid atherosclerosis, which may have biased the results.

3.3. Efficacy of Octopus OPCAB
Tables 5 and 6 summarise the efficacy outcomes for Octopus OPCAB from the comparative and case series studies.


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  		Table 5. Comparative study efficacy results for OPCAB with the Octopus Tissue Stabilizer®a

 

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  		Table 6. Efficacy results for OPCAB with the Octopus Tissue Stabilizer® – Level IV evidencea

 
Many studies did not specify whether they used additional traction to position the heart but of those that did, two studies used pericardial sutures [11,21], three used a suture and swab or suture and sponge/laparotomy pad combination [18,19,23], and one used gauze pads alone [16]. Snaring of the target artery was reported in 15 studies with sutures, silastic tapes or pledgeted sutures being used in nine studies. In addition, three studies used clamps [12,16,19], one used clamps and/or intravascular arteriotomy cannulas [21], another used flow through stents [11] and one used an intraluminal occluder [15]. Less than half (two comparative and seven case series studies) of the studies mentioned whether intracoronary shunts were used in their surgical technique. All of these studies, with the exception of Koh et al. [24] who specifically stated that shunts were not used, used intracoronary shunts in selective cases but did not detail the number of Octopus OPCAB patients this involved.

The need for perioperative conversion from Octopus OPCAB to CPB-CABG was reported in only one comparative study, and nearly half of the 13 patients converted had undergone previous coronary bypass surgery [19]. The same study reported the need for re-intervention in some Octopus OPCAB patients, in contrast to a nil requirement in the CPB-CABG group [19]. However, the follow-up period for this study was not stated which seriously limited the value of the data. The RCT by Baker et al. [11] found no difference between Octopus OPCAB and CPB-CABG with respect to composite clinical endpoint (defined as either a prolonged length of hospital or intensive care stay, or death within 30 days).

The rate of perioperative conversion from Octopus OPCAB to CPB-CABG ranged from 1.4 to 8% across six case series studies [14,18,20,23,26,27]. However, this may be a reflection of the fact that the case series studies generally had less detailed exclusion criteria for patients, if any at all, which meant that a higher proportion of relatively sicker patients may have been inadvertently included in the study sample. In addition, the level of expertise of the operators could also influence conversion rates, since case series often report the early results of feasibility studies on new surgical techniques.

A mix of arterial and venous conduits were used in all of the comparative studies, with the RCT [11] quoting the use of the left internal mammary artery 83.3% of the time during Octopus OPCAB, in comparison to 100% for the CPB-CABG patients. Arterial conduit use ranged from 34 to 100% in the four case series studies that quoted quantitative rates of arterial usage [20,21,26,27]. The majority of the other case series studies reported using a combination of arterial and venous conduits.

Few studies included postoperative follow-up data that extended beyond patient discharge and only two studies reported any angiographic follow-up data. These latter two studies reported at least 95% anastomosis patency following Octopus OPCAB [14,26]. However, these results were based on less than 60% of the patients who originally underwent Octopus OPCAB treatment.

3.4. Cardiac function and haemodynamics during Octopus OPCAB
Cardiac troponin T release from myofilaments in the myocardium is considered indicative of some degree of myocardial damage [28]. One level III-2 study [28] found that the mean coronary occlusion time for double vessel grafting with Octopus OPCAB was much lower than the cross-clamp time required in a similar set of patients undergoing CPB-CABG. Koh et al. [28] also showed that peak arterial coronary sinus cardiac troponin T levels during single and two vessel grafting with Octopus OPCAB were lower than those obtained during CPB-CABG, and that this peak level was independent of the length of coronary occlusion time during Octopus OPCAB. Net cardiac troponin T release peaked more quickly and at a higher value following CPB-CABG. Lactate production was undetectable after Octopus OPCAB but was present for the entire intraoperative course of CPB-CABG, despite a period of warm reperfusion before cross-clamp release. In addition, oxidative metabolism within the myocardium was less affected following Octopus OPCAB, compared to CPB-CABG. Kilger et al. [29] and Baker et al. [11] also showed that the release of troponin T and other cytosolic proteins was lower after Octopus OPCAB, in comparison to CPB-CABG.

The comparative study (level III-2/III-3 evidence) by Burton et al. [17] demonstrated that both Octopus OPCAB and CPB-CABG resulted in greatly increased levels of circulating vascular endothelial growth factor, which is indicative of myocardial ischaemic stress, to concentrations that were high enough to induce significant DNA synthesis in human coronary and aortic artery endothelial cells in vitro.

A small level III-3 study [24] demonstrated that the application of the Octopus Tissue Stabilizer® did not impair left ventricular function, and the case series by Gödje et al. [30] supported these findings. Coronary occlusion was found to depress global left ventricular function in patients who did not have left anterior descending artery collaterals but had minimal effect when collaterals were present. However, all cardiac disturbances resolved within 10 min of snare release [24]. Gödje et al. [30] and Mathison et al. [31] also found that the largest haemodynamic changes occurred during displacement for posterior wall vessels. Mathison et al. [31] showed biventricular contributions to the altered haemodynamics but that the main cause of haemodynamic instability during Octopus OPCAB was the disturbance of right ventricular diastolic filling by direct ventricular compression. Nierich et al. [16] observed that the resultant impairment of cardiac output during Octopus OPCAB in patients who did not have severely impaired left ventricles (40% preoperative ejection fraction in 81% of patients) could be generally corrected with fluid redistribution initiated prior to grafting.

3.5. Conventional CABG with CPB
Tables 7 and 8 represent an aggregation of data derived from many studies that may have employed different CPB-CABG clinical methods and technology. Therefore, the data presented on the safety and efficacy of CPB-CABG is not definitive and is only intended as a guide for general reference in comparing Octopus OPCAB case series study results with CPB-CABG.


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  		Table 7. Summary of CABG with CPB safety data

 

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  		Table 8. Summary of CABG with CPB efficacy data

 

   4. Discussion
Top
 Abstract
 1. Introduction
 2. Methods
 3. Results
 4. Discussion
References
 
Good studies are defined by rigid inclusion criteria, extensive evaluation, highly standardised treatment, validated and clinically relevant outcomes, a lengthy follow-up period and impartial investigators [32,33]. All of the studies available for review failed in at least one of these requirements.

4.1. Safety of Octopus OPCAB
The limited comparative data showed little difference in safety outcomes between Octopus OPCAB and CPB-CABG. The overall mortality rates reported in the case series studies for Octopus OPCAB were similar to rates reported from large series of CPB-CABG patients. However, the mortality rates for Octopus OPCAB were somewhat misleading in that many of the postoperative deaths reported in the case series studies occurred in patients that had multiple comorbidity prior to surgery. Such patients are often considered unsuitable for CPB-CABG.

Morbidity outcomes for Octopus OPCAB were not clearly defined as specific end-points in many studies. Therefore, it was unclear if some postoperative complications were not reported either because they were considered secondary to the main focus of the study or because they did not occur. Nonetheless, the incidence of adverse outcomes following Octopus OPCAB was generally lower following Octopus OPCAB, in comparison to CPB-CABG, and the serious complications often associated with CPB-CABG, such as renal failure and cerebrovascular accident, were largely absent in the Octopus OPCAB case series studies. Interestingly, preliminary RCT results indicated that the pattern of neuropsychological deficits following Octopus OPCAB was different to CPB-CABG at up to 6 months postoperatively, but that the rate of incidence of these deficits was the same [11]. Incidences of perioperative morbidity were reported in fewer patients in the Octopus OPCAB case series, compared to the large CPB-CABG series.

4.2. Efficacy of Octopus OPCAB
The limited comparative data available suggested that operative time, duration of ventilation, mean intensive care unit and hospital stay were similar for CPB-CABG and Octopus OPCAB. The small suction surface of the Octopus® attachment pods seemed to cause little damage to the myocardium and the likelihood of inadvertent intraoperative pod detachment appeared to be minimal. Many of the reported conversions from Octopus OPCAB to CPB-CABG occurred in re-operative patients or those with preoperatively impaired left ventricular function, and may be more attributable to patient selection rather than the Octopus® device itself. A comparison of the length of hospital stay between the Octopus OPCAB case series studies and the large CPB-CABG series was equivocal. The lack of information regarding length of follow-up made it difficult to compare postoperative variables, such as re-operation rate and angina free rates, with the large CPB-CABG series.

In the one comparative study that quoted it, the average number of grafts performed per patient was similar for both Octopus OPCAB and CPB-CABG [11]. Overall, seven of the ten case series studies/case reports that quoted the average number of grafts per patient achieved rates similar to those obtained in the large CPB-CABG series [16,20,23,26,27,31,34].

The gold standard for CPB-CABG is an arterial bypass using one or two internal mammary arteries [35] and this conduit is used in 79% of CPB-CABG grafts [36]. Similarly, internal mammary artery conduits were used in the majority of Octopus OPCAB grafts. Initial experience with OPCAB was generally confined to single vessel coronary artery disease but more recent studies have progressed to double and triple vessel revascularisation with Octopus OPCAB [11,19,20,27,31]. The limited angiographic follow-up data for Octopus OPCAB demonstrated good rates of short-term anastomosis and stenosis-free patency. However, it was impossible to compare this data or the re-intervention rates for Octopus OPCAB with the CPB-CABG case series data because the length of follow-up for the Octopus OPCAB studies was either incomparably short [26,34] or not stated at all [14,21,27].

4.3. Cardiac function and haemodynamics
The comparative data suggested that Octopus OPCAB caused significantly less damage to myocytes than CPB-CABG. This may be due, in part, to the shorter occlusion time and the more localised region of the heart affected by Octopus OPCAB [28]. The additional finding that Octopus OPCAB caused significant release of vascular endothelial growth factor into the systemic circulation may have potential ramifications for graft epithelialisation [17]. The study by Matata et al. [12] was not eligible for review because the comparator was not conventional CPB-CABG on an asystolic heart. However, their comparative results are worth noting because the only operative variable that differed between the two patient groups was the application of CPB. The study showed that Octopus OPCAB caused significantly less oxidative stress than CABG on a beating heart with CPB, and had little adverse effect on the inflammatory factors that are normally deranged by CPB [12].

Initially, access to all areas of the heart was often limited in patients with large hearts and/or poor ejection fraction [22]. In addition, some of the lateral marginal and circumflex branches are hard to access in Octopus OPCAB without causing right ventricular dysfunction and haemodynamic compromise [14]. Such haemodynamic disturbances can be largely overcome with selective and timely use of inotropic support and Trendelenburg positioning in patients who do not have severely impaired left ventricles [16,31]. However, it is still unclear whether these techniques are appropriate or effective in patients with unstable haemodynamics and left ventricular function impairment.

The increased sophistication in operative techniques employed to accommodate some of the limitations inherent in beating heart surgery was evident in many of the recent studies. In particular, Hart [20] found that the development and mastery of more effective surgical exposure techniques during the course of his study enabled rotation of the heart into the right chest with minimal ventricular compression. This meant that patients with circumflex artery disease, who were often considered ineligible for Octopus OPCAB because of the immense technical challenge they pose for the beating heart surgeon, were increasingly able to undergo Octopus OPCAB. However, other potential contraindications for Octopus OPCAB such as diffusely diseased vessels that require long anastomoses [10], coronary arteries with an intramyocardial course or deeply embedded in fat [11,14], and distal left anterior descending artery lesions [37] have yet to be clarified.

4.4. Considerations for further research
A continuing problem that hampers a scientifically rigorous comparison between CPB-CABG and Octopus OPCAB is that many of the non-randomised controlled studies do not recruit comparable patient groups for each study arm. Patients with single vessel disease and/or no diseased posterior wall vessels are often selected for the Octopus OPCAB study group while those with multivessel disease undergo CPB-CABG. The former patients are likely to present less technical difficulty for the surgeon. This inappropriate comparison between two mismatched patient groups can add confounding factors to operative outcomes and introduce a strong bias in favour of Octopus OPCAB for efficacy outcomes because the CPB-CABG patients are likely to require a more extensive and lengthy operation. However, it is often the sicker patients that are selected to undergo Octopus OPCAB because they are the most likely to benefit from avoiding CPB, which can then bias the safety outcomes in favour of CPB-CABG. This has already been shown by Baker et al. [11] whose results for the incidence of neuropsychological deficit differ from those of a previous study with less comparable study arms. However, properly designed RCTs routinely recruit elective patients, which can limit external validity because the results are not applicable to urgent/emergent patients who often have severely impaired left ventricular function. In addition, the difficulty in justifying the expense of conducting angiography in an asymptomatic patient following successful surgery and/or being able to entice such a patient to undergo follow-up examination is self-evident but leads to incomplete follow-up in many studies. Conducting properly designed RCTs in the clinical context is fraught with difficulty but it is nonetheless important that rigorous controlled testing of Octopus OPCAB continues.

To date, the value of the results reported in many studies has been limited by the lack of a uniformly applied patient stratification system to assist in comparing the pre- and postoperative status of patients both within and between studies. Inexplicably, some studies apply a grading system to quantify patients preoperatively but either fail to apply it postoperatively [16,19,27,31] or do so on only a small subset of the original patient group [13,18,21]. Obtaining unalloyed Octopus OPCAB data was also hampered by the common but inappropriate pooling of outcomes from different stabiliser types and/or surgical access routes. The suction capability of the Octopus Tissue Stabilizer® allows presentation and stabilisation of remote arteries that is not always feasible with the use of a compression stabiliser alone [38]. In addition, the technical requirements of the limited access approaches are vastly different from a median sternotomy. Hence, such data pooling can confound many operative outcomes including the number of grafts achieved per patient and perioperative conversion rates.

It has been noted that performing Octopus OPCAB requires a high level of skill and expertise [34,37]. Good communication between the anaesthetist and the surgeon is also essential to avoid dangerous haemodynamic compromise during heart displacement, particularly for posterior wall vessels [16]. For Octopus OPCAB to be able to match CPB-CABG in terms of efficacy, it must be possible to achieve complete revascularisation on the beating heart with only minor alterations in haemodynamics [27]. Thus, patient selection and surgical experience remain pivotal in the overall success of Octopus OPCAB.

4.5. Research recommendations
Octopus OPCAB may ultimately prove highly effective for patients with multiple co-morbidities or those with a very poor life expectancy without surgery that would be considered too high risk to undergo CPB-CABG [21,27]. With increasing expertise and refinements in technology and technique, it is likely that use of Octopus OPCAB in the more technically demanding patients will become commonplace, and that the contraindications and application of Octopus OPCAB may become more clearly defined than in the studies currently available. However, the ultimate position of Octopus OPCAB will depend on the evaluation of such outcomes as long-term anastomotic patency. More rigorous studies with longer follow-up periods and larger sample sizes must be conducted before a definitive conclusion can be reached regarding the safety and efficacy of Octopus OPCAB in comparison to CPB-CABG.

4.6. ASERNIP-S classification and clinical recommendations
The Review Group recommended that Octopus OPCAB be given a classification of ‘2’. ‘The safety and efficacy of the procedure cannot be determined at the present time due to an incomplete and poor quality evidence-base. It was recommended that an audit, be conducted to establish safety and efficacy’.

In addition, the following clinical recommendations were made to guide the development of Octopus OPCAB.

1. Octopus OPCAB should only be performed on appropriately selected patients by a properly trained cardiac surgeon. Before performing Octopus OPCAB, the surgeon should participate in a formal training workshop that includes surgical theory, animal wet lab experience, and an observational visit to a surgical unit that routinely performs Octopus OPCAB.

2. Cardiac surgeons should obtain institutional support and appropriately inform their patients before commencing Octopus OPCAB. Ideally, angiography with short-term follow-up should be performed on at least the first ten patients. This initial data can then be used by the institution to determine whether to proceed with the Octopus OPCAB programme, continue close surveillance or recommend further surgical training.

3. Minimal access approaches, such as limited thoracotomy, should only be attempted after an acceptable standard in full sternotomy has been achieved.


   Acknowledgments
 
The ASERNIP-S project was funded by the Australian Commonwealth Department of Health and Aged Care.


   References
Top
 Abstract
 1. Introduction
 2. Methods
 3. Results
 4. Discussion
 References
 

  1. Fitzgibbon G.M., Kafka H.P., Leach A.J., Keon W.J., Hooper G.D., Burton J.R. Coronary bypass graft fate and patient outcome — angiographic follow-up of 5065 grafts related to survival and reoperation in 1388 patients during 25 years. J Am Coll Cardiol 1996;28:616-626.[Abstract]
  2. Kurlansky P.A., Dorman M.J., Galbut D.L., Moreno N.L., Traad E.A., Carrillo R.G., Zucker M., Sanchez L., Ebra G. Bilateral internal mammary artery grafting in women — a 21-year experience. Ann Thorac Surg 1996;62:63-69.[Abstract/Free Full Text]
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