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J Thorac Cardiovasc Surg 2006;131:1382-1389
© 2006 The American Association for Thoracic Surgery
Cardiopulmonary Support and Physiology |
a Department of Pediatric Cardio-Thoracic Surgery, Royal Liverpool Children's NHS Trust, Alder Hey Hospital, Liverpool, United Kingdom.
b Department of Pediatric Cardiology, Royal Liverpool Children's NHS Trust, Alder Hey Hospital, Liverpool, United Kingdom.
Received for publication December 5, 2005; revisions received February 19, 2006; accepted for publication February 24, 2006. * Address for reprints: Georgios Kalavrouziotis, MD, PhD, Royal Liverpool Children's Hospital, Pediatric Cardio-thoracic Surgery, Eaton Rd, Liverpool L12 2AP, United Kingdom. (Email: gkalavrouziotis{at}yahoo.com).
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Abstract |
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 Top Abstract IntroductionPatients and MethodsResultsDiscussionReferences |
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METHODS: We reviewed the cases of 24 children supported with intra-aortic balloon pumping after cardiac surgery in our institution from 1994 through 2003.
RESULTS: Mean age at the time of the operation was 5.0 ± 5.6 years (range, 7 days-17.5 years). Ten patients were infants less than 6 months old. Mean weight was 18.9 ± 18.1 kg (range, 3.5-58.7 kg). Indications for intra-aortic balloon pump deployment were postoperative hemodynamic deterioration (n = 11, 8 survivors), failure to wean off cardiopu(n = 7, 5 survivors), and prophylaxis before weaning off cardiopulmonary bypass (n = 6, 5 survivors). The balloon was inserted through the ascending aorta in infants and through the femoral artery in children. Eighteen children (7 infants) were weaned off the intra-aortic balloon pump successfully (intra-aortic balloon pump survival, 75%). Mean duration of intra-aortic balloon pump support was 121.3 ± 140.60 hours (range, 8-670 hours). There were 3 post–intra-aortic balloon pump in-hospital deaths (survival to hospital discharge, 62.5%). Severe intra-aortic balloon pump–related complications were mesenteric ischemia in 1 patient and lower limb ischemia requiring intra-aortic balloon pump removal in 1 patient. At a mean follow-up of 85 ± 31 months (range, 18-124 months), all 15 long-term survivors were alive and well.
CONCLUSIONS: Use of an intra-aortic balloon pump is an effective modality of cardiac support in properly selected pediatric cardiac surgical patients with refractory low cardiac output. It can be safely used in small infants and neonates. In selected cases with known left ventricular dysfunction, there is a place for prophylactic use of an intra-aortic balloon pump.
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Introduction |
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TopAbstractIntroductionPatients and MethodsResultsDiscussionReferences |
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intra-aortic balloon pumping (IABP) has been a well-established mode of treatment for acute low cardiac output syndrome and cardiogenic shock after myocardial infarction or cardiac surgery in adults.
2
However, its use in children remains a rarity. Pollock and colleagues,
3
who first described the use of IABP in children in 1980, reported 80% survival in children older than 10 years but no survival in children younger than 5 years. The use of balloons of inappropriate size and "greater aortic elasticity" were thought to be the main culprits for the unsatisfactory results in children.
Our institution does not have an extracorporeal membrane oxygenation (ECMO) or ventricular assist device (VAD) program. Therefore we have used prolonged conventional cardiopulmonary bypass (CPB)
4
and, since 1994, IABP for cardiac support in children. Our initial experience (1994-1997) with 14 pediatric surgical patients supported with IABP has been published.
5
The present report summarizes the 10-year experience of our institution in the use of IABP in children undergoing cardiac surgery.
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Patients and Methods |
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TopAbstractIntroductionPatients and MethodsResultsDiscussionReferences |
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Age, BW, duration of IABP support, and length of stay in the intensive care unit (ICU) and hospital are expressed as mean values ± standard deviation. Group comparisons were performed with the Student t test and the 
2 test.
There were 14 (58.3%) boys. Mean age was 5.0 ± 5.6 years (range, 7 days-17.5 years; median, 2.5 years). Mean BW was 18.9 ± 18.1 kg (range, 3.5-58.7 kg; median, 12.3 kg). Ten (41.7%) children were infants (the infants group), with a mean age of 0.24 ± 0.16 years (range, 7 days-6 months) and a mean BW of 4.2 ± 0.7 kg (range, 3.5-5.8 kg). Fourteen children were older than 22 months (the children group), with a mean age of 8.4 ± 5.1 years (range, 1.8-17.5 years) and a mean BW of 29.5 ± 17.1 kg (range, 12-58.7 kg).
The selection of the appropriate balloon catheter for our patients was based on the Datascope guidelines for pediatric balloon sizing according to age and weight (Appendix E1).
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Indications and Timing of IABP Deployment
All 24 patients underwent cardiac surgery for congenital heart diseases (diagnoses and operations are summarized in Table 1). They were mechanically ventilated and receiving inotropic support at the time of IABP deployment with enoximone (n = 24, 100%), dobutamine (n = 22, 91.6%), adrenaline (n = 14, 58.3%), dopamine (n = 6, 25%), noradrenaline (n = 3, 12.5%), and vasopressin (n = 2, 8%). We consider adrenaline requirements greater than 0.05 µg · kg–1
· min–1 as a strong indication for initiating IABP.
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After minimal drain losses, the patients were started on continuous heparin infusion to maintain an activated partial thromboplastin time of 1.5 to 2.5 times normal value.
IABP Console
The Datascope System 97 pumping console (Datascope Medical Co Ltd, Cambridge, United Kingdom) with a pediatric volume-limiting chamber was used in 23 patients. One patient received a 34-mL balloon, and the Datascope System 90 was used because it was the only system available at the time. Helium gas is used for balloon inflation/deflation because its low viscosity allows quick pneumatic response to rapid heart rates with short cardiac cycle time, as is the rule in children. Manual filling of the balloon is performed every 45 to 60 minutes, unlike the adult device, which runs on an automatic filling system. Balloon pump timing was triggered either by the R-wave from the electrocardiogram (ECG) or the arterial waveform (in case of arrhythmia). Balloon frequency was 1:1, except during the weaning process. Augmentation time required manual adjustments for heart rate changes greater than 10 beats/min to obtain optimal diastolic augmentation and presystolic dip.
Weaning Off IABP
Weaning began at the physician's discretion, when hemodynamic stability was maintained (blood pressure normal for age, central venous pressure <10 mm Hg, left atrial pressure <10 mm Hg, urine output >2 mL · kg–1
· h–1, periphery-to-core difference in temperature <2°C, and no metabolic acidosis), and inotropic support was minimal (enoximone ± dobutamine <5 µg · kg–1
· min–1). Two-dimensional echocardiography was used to aid in the decision to wean. Improvements in the LV performance and its indices (shortening fraction and ejection fraction) were used as guidelines. The weaning procedure in our institution has been described previously.
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In brief, as a first step, the augmentation was gradually reduced to 50%. If this was tolerated for 4 to 6 hours, balloon frequency was reduced from 1:1 to 1:2 for 3 to 4 hours and then to 1:3 for 2 to 3 hours. The weaning procedure usually took 10 to 24 hours, depending on the status of the patient.
Removal of the Balloon
In case of direct cut-down of the femoral artery, the skin incision was reopened, the balloon was removed, and the exit at the artery was closed by means of direct suturing. If a side graft was used, the balloon was removed through the graft, which was doubly ligated with clips and cut off, leaving a small stump at the site of the arterial anastomosis. In case of insertion through the ascending aorta, through the open chest, the deflated balloon was carefully removed from the ascending aorta, while the purse-string suture was tightened down, closing the entrance hole. A mattress suture was placed at the insertion site for safety.
Follow-up
All long-term survivors were followed up in the outpatient clinic with clinical examination and echocardiography.
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Results |
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TopAbstractIntroductionPatients and MethodsResultsDiscussionReferences |
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There were 2 neonates in our series (a 7-day-old and a 19-day-old) with transposition of the great arteries who had an arterial switch operation. The former patient was weaned off CPB on IABP and a strong inotropic support. He had a global LV dysfunction and died 8 hours after surgical intervention. The latter patient was supported with IABP and was successfully weaned off after 670 hours of support, becoming a long-term survivor.
Concerning the timing of IABP deployment, survival was best among patients with IABP started prophylactically in the theater before attempting to wean off CPB (5/6 [83.3%]). The patient in this group who died despite the prophylactic insertion of an IABP (a 52-day-old female weighing 3.5 kg) had both coronaries originating from the pulmonary artery and a very poor ventricular performance because of extensive myocardial infarction. She was supported for only 8 hours before she died. Survival was poorer in patients with the IABP placed in the ICU (8/11 [72.7%]), as well as in patients who failed to wean off CPB before IABP initiation (5/7 [71.4%]), but these differences did not reach statistical significance.
The duration of IABP support ranged from 8 to 670 hours (mean, 121.3 ± 140.60 hours) for the whole series. In infants the mean IABP duration was 152.7 ± 196.39 hours (median, 106 hours; range, 8-670 hours) and in children it was 97.3 ± 86.70 (median, 60 hours; range, 12-260 hours; P = .37).
Patients who died on IABP support were supported for a mean of 18.8 ± 10.55 hours (range, 8-36 hours), whereas survivors of IABP were supported for a mean 155.6 ± 147.54 hours (range, 12-670 hours; median, 120 hours; P = .001). Patients who died were so severely sick that there was no time for the IABP to offer any help (all died within 48 hours after the operation).
Of the 18 patients who were weaned off IABP, 3 (2 children and 1 infant) died before discharge from the hospital (short-term survivors). One child (5.3-year-old female; BW, 12.6 kg; diagnosis: "single-ventricle physiology," atrial isomerism, common atrium, double-outlet right ventricle, transposition of the great arteries, atrioventricular septal defect, and pulmonary stenosis [PS]; status after bilateral bidirectional Glenn shunt) had completion of the Fontan procedure and was supported for 190 hours with IABP. Five days after successful weaning, she underwent exploratory laparotomy for peritonitis caused by mesenteric infarction and ischemic colitis. Colectomy with ileostomy was performed. She was re-explored 7 days later because of peritoneal abscess and died of sepsis 34 days after successful weaning off IABP.
The second child (2.5-year-old male; BW, 14 kg; diagnosis: tricuspid atresia, ventricular septal defect, and PS; previous modified Blalock-Taussig shunt) underwent a Fontan operation and was supported with IABP for 250 hours. He was successfully weaned off IABP but died 6 weeks later during the same hospitalization caused by extensive thrombosis of the superior vena cava and jugular veins.
The third short-term survivor was an infant (4.5-month-old male; BW, 4.5 kg) with "complete atrioventricular septal defect, common atrioventricular valve, and small left ventricle" submitted to pulmonary artery banding and aortopulmonary window. He was supported with IABP for 244 hours and was successfully weaned off. His postoperative course was complicated with temporary absent foot pulse, transient arrhythmia, and respiratory infection. He died of respiratory syncytial virus infection 31 days after weaning off IABP.
Morbidity
The complications observed in our patients can be arbitrarily be divided into 3 groups (Table 4):
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One infant was given a diagnosis of a clot in the left ventricle, which was dissolved after 3 days of formal anticoagulation therapy. Another infant experienced refractory arrhythmia requiring amiodarone infusion for 2 days immediately after surgical intervention.
Renal function was compromised in no case; on the contrary, urine output greatly increased after IABP institution, and in 5 cases the peritoneal dialysis instituted before IABP was discontinued.
Eleven patients (10 infants and 1 child) had the chest left open after surgical intervention. The IABP survivors had their chests closed after 5.9 to 28 days (median, 7 days). Neither sternal wound infection nor mediastinitis was noticed in the patients with a delayed chest closure.
The IABP survivors were mechanically ventilated for a median duration of 144 hours (range, 7-1370 hours); their median ICU stay was 12 days (range, 5-67 days), and the median total hospital stay was 21 days (range, 11-127 days).
Follow-up Results
All 15 discharged patients were followed up with regular clinical and echocadiographic assessment. They have all been alive and well for a mean of 7.1 years (range, 1.7-10.3 years). All have improved to normal ventricular function. One patient, a 4.3-month-old infant with ALCAPA syndrome who underwent intrapulmonary tunnel repair (Takeuchi procedure), showed evidence of PS on the echocardiogram performed on the 81st postoperative day. She had to undergo reoperation 5 months after the initial operation for relief of tunnel stenosis and supravalvular PS. At present (8 years after reoperation), she has persistent mild PS (pressure gradient, 30 mm Hg).
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Discussion |
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TopAbstractIntroductionPatients and MethodsResultsDiscussionReferences |
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The major reason for this is the fact that children with congenital heart disease usually have biventricular dysfunction and impaired pulmonary function (pulmonary hypertension). ECMO provides support of both the systemic and pulmonary ventricles and circulations. VADs are limited to support the ventricles. IABP supports both ventricles (increasing the diastolic pressure and perfusing the coronary arteries by means of balloon inflation) but mainly the left ventricle (reducing afterload during LV ejection by means of balloon deflation). ECMO and VADs are today the most prevalent means of mechanical circulatory assistance for children with congenital heart disease. Necessity is the mother of invention, and because our institution has no ECMO or VAD program, it forced us to use IABP in children for more than a decade. The present report chronicles the largest pediatric IABP experience in cardiac surgical patients. To the best of our knowledge, our series comprises the youngest patients and the patients with the smallest BW in the world literature who survived IABP.
The 75% survival (ie, successful weaning off) after IABP support in our series compares favorably with the reported survival in adults, as well as with that seen in other pediatric series (Table 5).
3,5,9-11
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reported survival of 50% (4/8) in infants versus 66.7% (14/21) in children older than 1 year. However, as in our series, the difference in survival between infants and children was not statistically significant. Although IABP is a quite different modality of mechanical circulatory support compared with ECMO, VADs, or both, we would attempt a rough comparison of their characteristics and results (Table E1).
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) ranged from 36% (neonates, up to 30 days) to 40% (children, 1-16 years) and 42% (infants, 31 days-1 year). In 2 recent single-center studies, survival of pediatric cardiac surgical patients admitted to the ICU was 40%.
13,14
Survival after LV assist device support in the series by Del Nido and coworkers
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was 71% (5/7) in infants with ALCAPA syndrome and severely compromised LV function. It is worth noting that all 5 survivors required re-exploration for bleeding from the cannulation site.
The Extracorporeal Life Support Organisation Registry Report Data (July 2004) on patients started on some form of extracorporeal life support (with ECMO or VADs) show a 58% survival of the extracorporeal life support and 43% survival to discharge from hospital or transfer to transplantation in children (57% and 38% in neonates, respectively).
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These results are definitely no better than those achieved with the IABP support.
The timing of IABP in our series ranged from before weaning off CPB up to 7 days postoperatively, highlighting the difficulty in decision making. The most important index is the clinical judgment of the surgeon on LV performance. In our series we have introduced IABP insertion before attempting to wean off CPB in cases involving preoperatively known poor LV function, as in patients with ALCAPA syndrome.
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Our first patient with ALCAPA syndrome was easily weaned off CPB after repair but 36 hours later had clinically and hemodynamically deteriorated and had to be started on IABP with a good and prompt response. Since then, we have started all our patients with ALCAPA syndrome on IABP before attempting to wean them off CPB.
6
The results (survival, 83.3% [5/6]) justified this aggressive policy. Of course, not all patients with ALCAPA syndrome need IABP support, but we would recommend prophylactic use of IABP in patients with preoperatively known severe LV dysfunction, using as criteria the degree of LV dilatation and the grade of the subsequent mitral valve regurgitation, as well as the clinical status of the patient.
Initiation of IABP in the theater, before attempting to wean off CPB, seemed to result in a better, although not statistically significant, survival in our series when compared with initiation after failure to wean off CPB or in the ICU. Chaturvedi and associates
13
also noticed a better survival when ECMO was begun in the theater than in the ICU (64% vs 29%, respectively), whereas Morris and coworkers
14
reported no difference.
In our series we used standard ECG timing methods for IABP inflation and deflation. Pinkney and associates
11
have used an echocardiographic timing technique as a more accurate method of balloon timing with aortic valve closure and opening. Although there is a theoretic background in the concept of the echo-timing technique (radial artery tracing might deviate up to 120 ms from the central aortic pressure tracing), the method of IABP timing does not seem to make a difference in the effectiveness of IABP support because in the above-mentioned report it is stated that "survival was not statistically better in the echocardiography-time era as compared with the standard ECG triggered timing era." We had no major problems in effectively supporting our patients with the ECG-triggered timing method, and our results confirm this.
In our early experience we have used IABP after the Fontan (or Glenn) procedure, but it was followed by a high incidence of failure to retrieve poor ventricular function: 4 (57%) of 7 patients were weaned off IABP (3 [43%] were discharged from the hospital). Similar experience has been reported by others
11,18-20
: of 16 patients undergoing the Fontan procedure, only 4 (25%) were successfully weaned off IABP. Pinkney and associates
11
recommend that "IABP should be used in this group only when the patient has primarily ventricular dysfunction rather than the low cardiac output state typically seen due to Fontan physiology...." Theoretically, IABP might benefit the single-ventricle physiology by reducing afterload and end-diastolic and filling pressures of the single ventricle. In fact, IABP seems not to be as beneficial as expected in the Fontan procedure, possibly because the causes of failure in Fontan physiology are multiple (eg, long-standing ventricular volume overload, increased pulmonary vascular resistance, and residual cardiac defects). We have abandoned the deployment of IABP for support of patients undergoing the Fontan procedure for several years. Our practice is that if the Fontan procedure does not work, we take it down and go back to the previous stage of bidirectional Glenn shunt.
Complications from IABP did appear in 3 patients in our series (in 2 they were severe). Others have reported no major complications caused by IABP resulting in fatality or IABP removal.
9-11
We had no complications in infants, in whom the balloon was inserted through the ascending aorta without the guide wire.
In conclusion, IABP has been proved to be an effective and life-saving adjunct to conventional medical treatment for cardiac support in properly selected pediatric cardiac surgical patients with refractory low cardiac output. Although not a substitute for ECMO or VADs, in centers with limited resources (eg, those in emerging countries), IABP can be an alternative for effective mechanical circulatory support. It can be used in children of all ages and, in fact, of all BWs with safety and with satisfactory early and long-term results. In neonates and small infants IAB insertion through the ascending aorta eliminates the risk of complications. In selected patients with preoperatively known severe LV dysfunction, there is a place for prophylactic use of IABP.
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References |
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TopAbstractIntroductionPatients and MethodsResultsDiscussionReferences |
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This article has been cited by other articles:
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  S. Paul Collison and K. Singh Dagar The role of the Intra-aortic balloon pump in supporting children with acute cardiac failure Postgrad. Med. J., May 1, 2007; 83(979): 308 - 311. [Abstract] [Full Text] [PDF]
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