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Ann Thorac Surg 1999;68:2320-2323
© 1999 The Society of Thoracic Surgeons
a Division of Cardiothoracic Surgery, University of California, Los Angeles Medical Center, Los Angeles, California, USA
Address reprint requests to Dr Marelli, Division of Cardiothoracic Surgery, UCLA School of Medicine, 10833 Le Conte Ave, Box 951741, Los Angeles, CA 90095-1741
e-mail: dmarelli{at}surgery.medsch.ucla.edu
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Abstract |
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 Top Abstract IntroductionPatients and methodsCommentReferences |
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Methods. Two cases are used to illustrate two methods of avoiding sternotomy during mechanical assist in children with dilated cardiomyopathy. One of these approaches avoids the need for extracorporeal oxygenation.
Results. Decompression of the left-sided chambers with a left atrial cannula decreased pulmonary edema and improved pulmonary function.
Conclusions. Pediatric patients with dilated cardiomyopathy may benefit from a left ventricular assist technique using a centrifugal pump, which avoids the neck vessels and sternotomy, as well as ECMO.
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Introduction |
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TopAbstractIntroductionPatients and methodsCommentReferences |
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ECMO has the advantage of supporting both heart and lung function but may cause increased inflammatory response [4]. Additionally, it does not completely decompress the left atrium, which may cause persistent lung dysfunction. Another ECMO disadvantage is differential regional oxygenation when arterial access is through the femoral artery, since the blood being perfused does not always completely reach the upper body. This has led to the use of neck cannulation in very small infants so that there is more efficient mixing of the ECMO blood with the less oxygenated blood coming from the left ventricle, as in the case of pulmonary edema. This ensures adequate perfusion of the brain with well-oxygenated blood and prevents limb ischemia which can occur with peripheral cannulation [5].
Avoiding the oxygenator of ECMO may be possible with a LVAD system [2]. This would more completely decompress the left atrium and facilitate resolution of the pulmonary edema. The LVAD system has commonly required a sternotomy to access the left atrium and ascending aorta. This can subject the patient to an increased risk of bleeding and need for transfusion prior to OHT. Also, sternal closure may not be possible, posing the risk of infection.
The purpose of this report was to use a minimally invasive approach to implant a LVAD system, which would avoid a sternotomy as well as upper or lower limb arterial cannulation.
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Patients and methods |
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TopAbstractIntroductionPatients and methodsCommentReferences |
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Surgical technique
She was taken to the operating room, and a right anterior thoracotomy was performed in the fourth intercostal space. Left atrial pressure was measured to be 30 mm Hg. A left atrial cannula was placed through the right superior pulmonary vein and Y attachment to the ECMO circuit was employed (Fig 1).
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Patient 2
A 25-month-old girl was referred because of severe dilated cardiomyopathy. She had been listed for OHT. She weighed 9.8 kg and had a body surface area of 0.47 m2. She presented to the surgical service with severe congestive heart failure requiring dopamine (15 µg/kg/min), dobutamine (15 µg/kg/min), milrinone (0.6 µg/kg/min), and epinephrine (0.25 µg/kg/min) to maintain hemodynamic stability. Echocardiogram showed global hypokinesis of both the left and right ventricles as well as the presence of a small clot in the left ventricle. Blood pressure was 75/45 with a heart rate of 200 bpm, and mechanical ventilation was required. The PaO2 was 90 on an FiO2 of 80 and chest roentgenogram showed pulmonary edema.
Surgical technique
The child was taken to the operating room where a small (4 cm) left anterior thoracotomy was carried out (Fig 2). The internal mammary artery and vein were divided (Fig 3). After entering the intercostal space, the left lobe of the thymus was excised. A retractor was used to gently lift the sternum anteriorly for better visual access to the central mediastinum [6]. The pericardium was incised and suspended, allowing access to both the ascending aorta and left atrial appendage. Pursestrings were constructed using 4-0 polypropylene suture. Aortic cannulation was carried out with a 14F straight THI cannula. Because the aorta was at a distance, special care was taken to control the cannulation site. A side-biting clamp appeared cumbersome within the limited operative field. An aortic suture was placed, using a continuous double circle; the first pass in the media and the second pass in the adventia creating a pulley mechanism. An additional pursestring suture was then used for reinforcement. Cannulation was achieved by controlling the aortic site with three forceps (two for the assistant). The surgeon was then able to cut down on the media of the aorta (within the pursestring) using a number 11 blade. The intima was not opened. Gauze was used to dry the site, and the aortic cannula was then pushed through the last cell layer of intima to complete a bloodless entry. Left atrial appendage cannulation was achieved using a pediatric vascular C clamp. A 20F metal Pacifico right-angled cannula (DLP, Grand Rapids, MI) was used. Two separate pursestrings were used. The four snares were secured to their respective cannulas separately and locked using sterile buttons to avoid the use of hemostatic clamps (Fig 4). After deairing and connection to the centrifugal pump system, left ventricular assist was initiated at 0.8 L/min. A single chest tube was brought out through a separate stab incision and the incision was closed in layers.
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This was necessary to support the right ventricular output. Central venous pressure was 9 to 12 with a systemic mean arterial pressure in the 80s. Urine output averaged 5.5 cc/kg/h and creatinine was 0.4 mg/dL. The PaO2 was 160 on an FiO2 of 35% and the chest roentgenogram showed improving pulmonary edema. Activated clotting time was maintained at 180 to 200 seconds with adjustment of a heparin drip. Left ventricular ejection over the LVAD was minimal as reflected in the arterial line tracing. The serum glutamic-oxaloacetic transamine was 138 and the serum glutamic-pyrovic transamine was 108, preoperative values had been 787 and 398 respectively. The child was examined 4 times a day for neurological complications.
Transfusion requirements over the first 7 days were 310 cc of red blood cells, 450 cc of fresh frozen plasma (FFP) and 670 cc of platelets. There were standing orders to keep hemoglobin at 10, the platelet count greater than 100K and the international normalized ratio (INR) 1.5. There was no need for chest reexploration. During the next 7 days a donor heart was still not available. Transfusion requirements were 500 cc of red blood cells, 60 cc of FFP and 200 cc of platelets. The LVAD circuit was changed only once after 1 week, due to hemolysis evidenced by increasing hematuria.
On the tenth day of support, a change was noted in the child’s neurological examination and a subdural hematoma was diagnosed. This was drained by the neurosurgery service. Follow-up examinations improved, but 5 days later they deteriorated severely once again. Because of the poor potential for neurological recovery, support was withdrawn.
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Comment |
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TopAbstractIntroductionPatients and methodsCommentReferences |
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Options for mechanical support in the pediatric age group include several strategies. The most universally applicable support is ECMO [1, 4]. This comprises a centrifugal or roller pump combined with extracorporeal oxygenation, essentially a cardiopulmonary bypass. Larger children (> 30 kg) requiring mechanical cardiac assist have the option of external pulsatile devices or if body surface area is greater than 1.5 m2 implantable left ventricular assist devices (eg, TCI HeartMate) [3].
ECMO strategy has been useful in small infants (< 10 kg) in conjunction with carotid artery and jugular vein cannulation. This has the advantage of complete heart and lung support without sternotomy, thereby minimizing the risks of bleeding and infection during the wait period. It has the disadvantage, as illustrated in the first case presented, of incomplete decompression of the left atrium and ventricle which can lead to pulmonary edema and lung dysfunction. We have observed this despite inotropic support. This led us to decompress the left-sided chambers using a right minithoracotomy, with insertion of a cannula in the right superior pulmonary vein. Alternatively, the left ventricular apex can be accessed using a left minithoracotomy at the level of the apical impulse.
For larger infants and children, arterial access through the carotid arteries has not gained widespread acceptance because of the risk of cerebrovascular accident. Options include subclavian and femoral artery cannulation. Although the former may be feasible, access may be difficult to achieve and there is a risk of limb ischemia over time. Femoral artery cannulation for ECMO has the additional disadvantage of not ensuring the delivery of oxygenated blood to the aortic arch unless cardiac function is completely depressed. This must be balanced against incomplete emptying of the left-sided chambers and persistent pulmonary congestion, accentuated in the presence of a history of cyanotic heart disease and increased bronchial artery flow.
The approach described in patient 2 has several advantages in addressing these issues. It avoids the unnecessary use of extracorporeal oxygenation for a primary cardiac problem, and therefore may minimize the inflammatory response initiated by the mechanically-driven circulation. It precisely decompresses the left-sided cardiac chambers and does not require cardiopulmonary bypass for initiation.
Our cannulation technique avoided both peripheral arterial cannulation and sternotomy. Our approach also permits measurement of left atrial pressure, although there is a risk of air embolism if such lines are not carefully managed. Avoiding a median sternotomy prior to heart transplantation is obviously beneficial, particularly if the child has had previous cardiac surgery. The aortic cannulation technique described in patient 2 makes use of the fact that the sternum is very flexible in children. The double circle purse-string suture creates a pulley, so that if control of the aorta was lost it could be pulled to close the bleeding cannulation site. This was a real risk, since the aorta was at a distance and the use of vascular clamps would have been difficult. As an extra measure of safety we chose the THI angled cannula which has a long tip and therefore reduced the risk of dislodgment.
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This article has been cited by other articles:
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  V. Fouilloux, L. Lebrun, L. Mace, and B. Kreitmann Extracorporeal Membranous Oxygenation and Left Atrial Decompression: A Fast and Minimally Invasive Approach Ann. Thorac. Surg., June 1, 2011; 91(6): 1996 - 1997. [Abstract] [Full Text] [PDF]
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