Ann Thorac Surg 2007;84:1414-1415
© 2007 The Society of Thoracic Surgeons
How To Do It
Right Heart Operations Without Cardiopulmonary Bypass: The Use of Temporary Total Cavopulmonary Connection
Ahmad Ali Amirghofran, MD,
Abbas Emami Nia, MD*
Department of Cardiac Surgery, Shiraz University of Medical Sciences, Faghihi Hospital, Shiraz, Iran
Accepted for publication February 14, 2007.
* Address correspondence to Dr Emami Nia, Division of Cardiac Surgery, Department of Surgery, Faghihi Hospital, Shiraz, 71348-44119, Iran (Email: emaminia{at}gmail.com).
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Abstract
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Although cardiopulmonary bypass is essential for most cardiac operations, it is preferable to avoid it because of its nonphysiologic nature and complications. For coronary artery bypass surgeries, off-pump methods have been developed, but few advances have been made for intracardiac operations. We have developed a technique to perform operations inside the right heart chambers without using cardiopulmonary bypass. In this technique, blood from cavae is directly guided toward the pulmonary artery using cannulas.
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Introduction
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Although the conduct of cardiac surgery with cardiopulmonary bypass has evolved with continual reduction in morbidity and mortality, it is known to induce a pro-inflammatory state with several adverse consequences [1, 2]. In recent years, off-pump coronary artery bypass surgery has become popular to prevent such events, but for operations inside the heart chambers, not much success has been achieved.
We have tried to develop a technique for performing operations inside the right side of the heart without using cardiopulmonary bypass. The designed system, called temporary total cavopulmonary connection (T-TCPC) is based on directing superior vena cava and inferior vena cava venous blood into the pulmonary artery.
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Technique
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The Ethics Committee of Faghihi Hospital approved this study and waived the need for patient consent. A median sternotomy is performed and heparin is given as for routine cardiopulmonary bypass. Pursestring sutures are placed on the right atrial appendage and inferior vena cava right atrium junction. Another longitudinal pursestring is placed over the main pulmonary artery, beginning just distal of the pulmonary valve and continuing downward to near the bifurcation. Tapes are passed around the superior vena cava, inferior vena cava, and pulmonary artery (PA) (Fig 1). First, the right atrial appendage is cannulated, and the cannula is guided to the superior vena cava. The inferior vena cava is cannulated in the same manner. Both cannulae are then connected to a "Y"-connector with a side hole (the tapes are not tightened at this point). Next, the anterior wall of the pulmonary artery is caught by a side-biter Satinsky clamp (Aesculap Inc, Center Valley, PA), and a longitudinal incision is made inside the previously placed pursestring. A double-stage venous cannula with a short distal tip is then used for pulmonary artery cannulation. This cannula is pushed into the pursestring incision and inserted into the pulmonary artery while the assistant removes the side-biter clamp. The distal tip is guided toward the left pulmonary artery such that the side holes of the cannula face the orifice of the right pulmonary artery. The pursestring is then tightened. Alternatively, a side tube-graft can be sewn on the main PA as an inflow, both to get the cannula out of the PA and simplify inserting and removing the tubes.
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Fig 1. Temporary total cavopulmonary connection (T-TCPC) system. The superior vena cava (SVC) and inferior vena cava (IVC) were cannulated and connected to the pulmonary artery (PA) cannula through a side branched "Y" connection with a three-way tab. All three vessels were snared. The arrows show the blood flow from cavae to the pulmonary artery. The dashes show the place where tapes are located. (RA = right atrium; RV = right ventricle.)
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The pulmonary artery cannula is filled with blood and clamped proximally; this is done to prevent premature emptying and avoid drawing air into the PA. The cannula is then connected to the exit of the three-way Y-connector. The superior vena cava and inferior vena cava are snared at this time, which will cause upward movement of the blood in the cavae cannulas due to higher central venous pressure. The air inside the cannulas will spontaneously move out through the side hole of the Y-connector, and the air will be removed from the system. The pulmonary artery cannula is unclamped at this point, and temporary cavopulmonary circulation will flow.
It is important that the establishment of circulation does not take long, as cardiac output will drop just after insertion of the PA cannula due to partial obstruction of right ventricular outflow. In addition, if baseline central venous pressure (CVP) is low, the filling of the tubes and removal of air will take longer, causing a more significant temporary drop in blood pressure.
Blood pressure will gradually stabilize while the left side of the heart ejects blood and maintains body circulation. However the right side of the heart will remain empty. The right atrium can then be opened. The blood coming through the coronary sinus should be removed to maintain a bloodless field. This is done by suctioning this blood into a reservoir using pump suctions and then pumping it back into the circulation through a small extension line connected to the side hole of the Y-connector. The main part of the operation can now be done through an atriotomy or even a ventriculotomy.
Even in cases in which a patent foramen ovale is missed in preoperative examination, air emboli should not produce complications because the left atrium is blood filled with a positive pressure of 5 to 10 mm Hg and the right atrium is empty. As a result, the flow through the patent foramen ovale will always be from left to the right, preventing air from entering the left atrium. The blood coming from the patent foramen ovale can be suctioned for a few seconds, and the patent foramen ovale is closed with simple suturing.
At the end of the operation, the right atriotomy is closed. All tapes are loosened and the pulmonary artery cannula is removed, followed by the vena cavae cannulas.
We have used this technique in 5 patients (mean age, 21 years; range, 9 to 28 years). Three patients had tricuspid valve endocarditis, 1 had a fungal right atrial mass, and 1 had a right ventricular outflow tract obstruction. Four patients were critically ill with signs of widespread infections after endocarditis.
All patients tolerated the procedure well. The mean T-TCPC time was 28 minutes (range, 13 to 41 minutes). The CVP raised by a mean of 12.3 mm Hg (range, 10.6 mm Hg to 22.9 mm Hg). The lowest CVP during this time period was 16 mm Hg and the highest reached was 30 mm Hg. The systolic blood pressure decreased by a mean of 23.8 mm Hg, from 106.5 mm Hg to 82.7 mm Hg. All patients left the operating room in stable conditions and were discharged form the hospital without any complications.
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Comment
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To the best of our knowledge, this is the first report published in the literature describing the use of this type of circulation for cardiac surgery. The T-TCPC circulation is in essence a Fontan-type circulation. However, the difference is that the resistance of the tubes causes high gradients between the CVP and PA pressure. This will cause a temporary rise in CVP and a decrease in systemic blood pressure. Despite this fact, the T-TCPC circulation seems to be well tolerated for short-time operations.
The CVP at the beginning of the operation, before starting the cannulation, should be set to higher levels; otherwise the drop in blood pressure at the start point will be more significant.
The presence of the three-way tab in the mid part is essential, as it is used both for the process of the removal of air and for transfusing the blood back to the patient.
During the T-TCPC circulation the blood pressure will depend greatly on the CVP. Comparison of CVP and systemic pressure curves shows that CVPs lower than 18 to 20 mm Hg may cause systemic pressure to drop below 50 mm Hg in some patients. As a result, the systemic pressure can be maintained in a reasonable level by manipulating the rate of back transfusion to the patient.
As is evident, the advantage of this method may be the absence of long tubes, a pump, and an oxygenator; as a result, less inflammatory response is expected. High PA pressure contraindicates using T-TCPC as it does for Fontan circulation, but the optimal PA pressure, which is suitable for the T-TCPC circulation, needs to be determined in larger studies. Any type of connection between the left and right heart systems, such as septal defects or patent foramen ovale will also cause massive amounts of blood passing the connection toward the open, empty right chambers. Consequently, the patient should have reliable echocardiography focused on PA pressure and the intracardiac anatomy prior to the operation.
In conclusion, the T-TCPC technique seems to be a reasonable and safe way to avoid cardiopulmonary bypass in dealing with right heart operations that do not last very long. The contraindications and technical points should be kept in mind for favorable results.
It is noteworthy to mention that the aim of this study is not to suggest this technique as a replacement to cardiopulmonary bypass, rather as an alternative method in performing right heart operations. Further and more extensive studies need to be done in the future.
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References
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- Edmunds Jr LH. Inflammatory response to cardiopulmonary bypass Ann Thorac Surg 1998;66(5 Suppl):S12-S16discussion S25–8.[Abstract/Free Full Text]
- Boyle Jr EM, Pohlman TH, Johnson MC, Verrier ED. Endothelial cell injury in cardiovascular surgery: the systemic inflammatory response Ann Thorac Surg 1997;63:277-284.[Abstract/Free Full Text]
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Abstract
Introduction
