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Eur J Cardiothorac Surg 1999;16:S43-S47
© 1999 Elsevier Science NL

Patient selection for Port-Access^TM multi vessel revascularization

^a Department of Thoracic and Cardiovascular Surgery, J.W. Goethe University, Theodor Stern-Kai 7, D-60590 Frankfurt am Main, Germany
^b Department of Anesthesiology, Intensive Care, and Pain Therapy, J.W. Goethe University, Theodor Stern-Kai 7, D-60590 Frankfurt am Main, Germany

^* Corresponding author. Tel.: +49-69-6301-6141; fax: +49-69-6301-5849

	Abstract

Top Abstract 1. Introduction 2. Patients and methods 3. Results 4. Discussion 5. Conclusions References

 
Minimally invasive multivessel revascularization is rarely performed due to the difficult exposure of the aorta as well as the complete coronary anatomy through a small thoracotomy. The Port-Access^TM technique bears additional contraindications for this procedure, which limits its potential as compared with other approaches to ‘less invasive surgery'. Our aim was to show the applicability of this surgical technique to a wide range of patients with coronary artery disease. In our initial experience with this method (31 patients), the quality of anastomoses, graft patency, and clinical outcome are good, and do not differ from standard multivessel coronary artery bypass grafting. Port-Access^TM multivessel revascularization can be performed safely and is appropriate for a large patient population.

Key Words: Port-Access surgery • Coronary artery bypass grafting • Minimally invasive cardiac surgery

	1. Introduction

Top Abstract 1. Introduction 2. Patients and methods 3. Results 4. Discussion 5. Conclusions References

 
‘Minimally invasive' cardiac surgery is a multi-facetted term. In coronary artery bypass grafting (CABG) it relates to two completely different philosophies: On one hand cardiopulmonary bypass (CPB) is abandoned, and revascularization is performed in most cases after complete median sternotomy to access nearly all coronary segments on the beating heart [1,2]. A small thoracotomy allows grafting to the anterior and upper lateral wall only [3]. In both cases mechanical devices are necessary to stabilize the anastomotic site [4]. The rationale behind these ‘beating heart procedures' is a postulated avoidance of a CPB-related inflammatory response, resulting in coagulation disorders, membrane damage and consecutive organ failure [5].

On the other hand CPB with femoral or direct cannulation [6,7] allows complete revascularization through limited incisions on the arrested heart. The surgical trauma is reduced, and the integrity of the chest is maintained. The Port-Access^TM system is one of several technological approaches to perform these procedures.

Since we do consider the clinically relevant pathogenicity of CPB acceptable in low-risk patients [8], we assessed the applicability of the Port-Access^TM system for multivessel revascularization.

	2. Patients and methods

Top Abstract 1. Introduction 2. Patients and methods 3. Results 4. Discussion 5. Conclusions References

 
From November 1997 to October 1998, 31 patients (six female, 25 male) underwent Port-Access^TM multivessel revascularization at our institution. Mean age was 64.8±5.9 years and mean ejection fraction 58±11%. Eight patients were in NYHA functional class II, 18 in class III, and five in class IV. Three patients suffered from single vessel, 17 from double vessel, and 11 patients from triple vessel disease. The exclusion criteria are listed in Table 1 .

The Port-Access^TM system (Heartport, Redwood City, CA) consists of a coronary sinus catheter and a pulmonary vent, both inserted via the jugular vein. Venous drainage is performed by a long femoral cannula, which is advanced into the right atrium. The femoral arterial return cannula has an additional port for the insertion of the endoaortic balloon clamp. Antegrade cardioplegia is administered via the central lumen of the catheter of this clamp, which also serves as aortic root vent.

Prior to the surgical intervention the coronary sinus catheter and the pulmonary vent are positioned by the anesthesiologist via the jugular vein under echocardiographic guidance.

A 6–9 cm skin incision is performed anterolaterally upon the left fourth rib in males, or in the submammarian groove in female patients respectively. Internal thoracic artery (ITA) takedown is then conducted under direct or video-assisted vision. Initially this was performed through the 4th intercostal space (IS). In these cases a resection of the ventral part of the 4th rib was often necessary to reach the ascending aorta. In the last eight patients the operation was carried out completely through the 3rd IS thus maintaining the integrity of the chest while achieving better exposure. Double-lumen endotracheal intubation greatly facilitates this procedure, but is not mandatory.

A small oblique incision is performed in the groin not used for coronary angiography, and after systemic heparinization the femoral artery and vein are cannulated for CPB under transesophageal echocardiographic or fluoroscopic control. Following the onset of CPB, the endoaortic balloon clamp is advanced into the ascending aorta [9]. A pericardial cradle is created and proximal anastomoses are performed first after exact exposure of the aorta. This can be achieved by placing stay sutures in the duplicated pericardium on top and bottom of the superior vena cava. By pulling on these sutures, using the sternum as a hypomochlion, the aorta is rotated towards the operative field (Fig. 1).

View larger version (143K): [in this window] [in a new window]   Fig. 1. Exposure of the aorta by placing stay sutures in the duplicated pericardium on top and bottom of the superior vena cava.

After deflation of the endoaortic balloon, the patient is weaned from CPB. Before closing the chest, an intercostal block is performed with 100 mg of Bupivacain.

Postoperative care generally does not differ from conventional procedures and patients can be weaned rapidly from mechanical ventilation.

Biochemical and clinical variables were collected sequentially throughout the hospital stay. To verify the quality of revascularization, a control coronary angiography was conducted before discharge in the first 20 patients.

	3. Results

Top Abstract 1. Introduction 2. Patients and methods 3. Results 4. Discussion 5. Conclusions References

 
3.1 Intraoperative data
In 31 patients, a total of 71 bypass grafts were performed (31 ITA grafts with 34 anastomoses and 39 saphenous vein grafts with 45 distal anastomoses). Mean operating time was 298±78 min, mean bypass time was 122±20 min, and mean aortic crossclamp time was 55±14 min (one patient, who suffered retrograde aortic dissection is not included in these data).

3.2 Routine biochemical markers
There was no significant increase in cardiac enzymes after surgery (mean CK 588±202 IU/l; mean CK-MB 14±7 IU/l; mean troponin T 0.33±0.11 ng/ml; all 5 h postoperatively). Renal function was not impaired (mean creatinine was 1.0±0.2 mg/dl, mean BUN 29.6±5.5 after 24 h).

3.3 Blood loss and transfusion
Postoperative chest drainage was remarkably high as compared with conventional procedures (mean chest drain blood loss: 924±502 ml). Transfusion requirement was comparatively low (four patients needed 600 ml of packed red cells each; five patients were substituted together with 700 ml of fresh frozen plasma).

3.4 Clinical outcome variables
Postoperative ECG monitoring with automatic ST-segment monitoring displayed no signs of myocardial ischemia. Mechanical ventilation lasted 21.5±16.0 h, CCU stay 1.6±0.9 days, and postoperative hospital stay 9.2±2.3 days. There was remarkably reduced pain expression, when an intercostal block was performed, which was added to our protocol after the first five patients. Skin incision for the small thoracotomy was limited to a mean length of 8.0±1.1 cm.

3.5 Coronary angiography
The first 20 patients underwent coronary angiography prior to discharge. There was a 100% patency rate with only one 60% stenosis in the middle of an ITA graft. All anastomoses were free from stenosis.

3.6 Mortality and morbidity
There was no early and no late mortality among the 31 patients.

We experienced one retrograde dissection of the aorta in a patient with double vessel coronary artery disease immediately after installing CPB. After conversion to median sternotomy, the ascending aorta was replaced in addition to CABG and the patient was discharged on postoperative day 8 after uneventful recovery. Histological assessment showed a severe medionecrosis of the aortic wall.

One patient suffered an outright stroke. One reexploration for bleeding of a distal anastomosis could be performed through the lateral thoracotomy.

Cardiopulmonary resuscitation was necessary in one patient, who was extubated in the operating room after an uneventful intraoperative course, due to respiratory distress after transfer to the CCU. An unfavorable prognosis of the postoperative neurologic deficit has to be considered.

	4. Discussion

Top Abstract 1. Introduction 2. Patients and methods 3. Results 4. Discussion 5. Conclusions References

 
Alternatively to the Port-Access^TM approach, multi vessel revascularization on CPB through a left anterior small thoracotomy can be performed with the ‘Dresden technique' [7]. The distal ascending aorta with respect to the aortic arch is cannulated and clamped conventionally through the operative site. However, this approach does not allow to reduce the length of skin incisions down to 6 cm, as practiced in the present patient population. In case of a contraindication for the Port-Access^TM approach due to peripheral artery disease, we use the aortic crossclamp as described by Chitwood [10] inserted through a small lateral stab wound to avoid enlargement of the small thoracotomy. However, these patients are not included in the present manuscript. A new arterial return cannula providing antegrade flow will soon become available (Heartport, Redwood City, CA). This device will be introduced through a port in the 2nd IS. The aorta will be cannulated under direct vision and the endoaortic balloon placed in the usual fashion. The risk associated with retrograde arterial flow will thus be avoided. Possible dislocation of the balloon will be reduced due to the short length of the catheter.

Patients under 60 years of age are excluded from this procedure, because it is our policy to revascularize this subgroup with bilateral ITA grafts, which would result in unacceptably long operating times. This may change in the future, when thoracoscopic techniques [11] for ITA takedown will be established routinely. In the presence of two vessel disease without involvement of the circumflex coronary artery we use only a single ITA graft to the LAD, because there is no evidence for superior patency rate of ITA grafts to the right coronary artery [12]. In patients with a high risk of CPB associated complications, a beating heart procedure [4] has to be considered for this subgroup.

Calcification or plaques in the ascending aorta are contraindications for the endoaortic balloon clamp, to avoid possible cerebral particulate embolization or even rupture of the balloon. The diameter of the ascending aorta is important, because the balloon cannot sufficiently occlude an ectatic aorta larger than 3.5 cm. To assess the ascending aorta, preoperative transthoracic echocardiography is mandatory.

Aortic aneurysms, especially with a mural thrombus, as well as stenoses of the iliac or femoral arteries impair retrograde blood flow, increase the risk of cerebral particulate emboli and complicate the advancement of the endoaortic balloon clamp. Therefore femoral vessels must be studied by duplex sonography preoperatively. The limited sensitivity of this examination may produce false normal findings, which advocates angiographic examination. This can easily be performed within the scope of coronary catheterization, but has been adopted only by few referring cardiologists, despite our educational activities.

In cases of mild or moderate aortic regurgitation, retrograde cardioplegia via a coronary sinus catheter is mandatory, because the left ventricle is not vented, and infusion of antegrade cardioplegia via the aortic root would increase wall stress in the left ventricular myocardium. In cases with a completely sufficient aortic valve, some centers spare the coronary sinus catheter as well as the pulmonary vent. We believe, those two catheters are a good backup, especially, if the tip of the endoaortic balloon clamp becomes obstructed by the aortic wall due to malpositioning.

Operating time was clearly longer, but did not impair clinical outcome. A comparatively long learning curve needs to be considered to develop special surgical skills using new instruments, and to significantly decrease fluoroscopy time by placing most catheters under echocardiographic control.

Sufficient myocardial protection can be achieved with the Port-Access^TM system, and combined ante/retrograde blood cardioplegia resulted in low laboratory markers of myocyte injury.

Blood loss was remarkably high, but transfusion of blood products remained within the range of conventional CABG.

The early postoperative chest X-ray reproducibly showed considerable interlobar effusion or hematoma respectively. This may be associated with single lung ventilation and the lateral positioning of the chest tube, and should not be confused with a plate like atelectasis.

The most deleterious complication of this technology is retrograde ascending aortic dissection [13]. There is an ongoing discussion on whether retrograde arterial flow itself, or the introduction of the guidewire with respect to the endoaortic balloon clamp are responsible for this serious adverse event by causing mechanical intimal lesions. We experienced one aortic dissection immediately after the onset of CPB, with the balloon clamp already positioned in the ascending aorta, which prohibits identification of a single risk factor. After this event, our strategy was modified, and we currently establish low flow from the groin before placing the guidewire and the endoaortic balloon clamp, respectively. The endoclamp was modified recently with a softer tip. We advise to always cannulate the femoral artery not used for coronary angiography, because small intimal tears are often present after catheterization [14].

Severe stroke has been documented in 0.6% of cases in the Port-Access^TM International Registry. After displaying the clinical symptoms of stroke, one of our patients showed a bilateral cerebral infarction in the postoperative CT scan. In this patient it took several attempts, to place the intraaortic balloon clamp in the ascending aorta, which was only monitored by echocardiography. Following this complication, we have always added fluoroscopy, if the guidewire could not be seen in the ascending aorta after the first insertion. Again, preoperative screening by transthoracic echocardiography as well as verification of these findings by intraoperative transesophageal echocardiography are mandatory to help avoid neurological complications.

Since one of the aims was to decrease mechanical ventilation time, the excitement about the excellent results in the first series of patients led to four consecutive early extubations in the operating room. Cardiopulmonary resuscitation had to be performed in the last of these patients due to respiratory distress after transfer to the CCU. Since operating times are still very long and transport to the CCU is a critical phase after cardiac surgery, it is our policy now to wean patients from mechanical ventilation in the CCU.

Postoperative coronary recatheterization was performed in the first 20 patients of our cohort. The results were excellent including cases with quadruple and quintuple bypass grafting. This demonstrates, that all coronary segments can be grafted with the Port-Access^TM technique and there are no contraindications due to coronary anatomy.

One rationale behind minimally invasive cardiac surgery is to reduce surgical trauma, resulting in decreased time on mechanical ventilation, CCU and hospital stay respectively. A shorter period of rehabilitation can be expected, as well as an early return to work. In addition this procedure is intended to allow substantial cost reduction. For our initial patient population, this could not be achieved for the time of hospital stay. Clinical outcome did not differ from our conventionally operated patients, except for excellent cosmetic results.

According to reports from the rehabilitation centers, patients, who had cardiac surgery through a small thoracotomy, showed a more rapid recovery in the 2nd postoperative week. This is probably due to maintained chest integrity, but has to be proven in prospective randomized quality of life trials.

	5. Conclusions

Top Abstract 1. Introduction 2. Patients and methods 3. Results 4. Discussion 5. Conclusions References

 
From our initial experience we conclude, that Port-Access^TM multivessel bypass grafting can be performed safely, but requires longer operating time. All target vessels can be accessed and postoperative angiograms display excellent results. This approach using CPB allows the highest quality of anastomoses, and therefore is a good alternative in a low risk patient group. Occlusion of the ascending aorta is no additional risk in this procedure. Contraindications due to descending and abdominal aortic as well as peripheral artery disease will be overcome by future technologies, thus increasing the patient population suitable for Port-Access^TM surgery.

	Acknowledgments

 
The authors are greatly indebted to Mark Groh, Asheville, NC, USA, for providing the excellent illustration.

	References

Top Abstract 1. Introduction 2. Patients and methods 3. Results 4. Discussion 5. Conclusions References

 

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This Article Abstract Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Add to Personal Folders Download to citation manager Author home page(s): Gerhard Wimmer-Greinecker Georg Matheis Selami Dogan Tayfun Aybek Anton Moritz Permission Requests Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Wimmer-Greinecker, G. Articles by Moritz, A. Search for Related Content PubMed PubMed Citation Articles by Wimmer-Greinecker, G. Articles by Moritz, A.