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Eur J Cardiothorac Surg 2004;26:44-53
© 2004 Elsevier Science NL
a Department of Pediatric Cardiac Surgery, S. Orsola-Malpighi Hospital, University of Bologna Medical School, Via Massarenti, No. 9, Bologna, Italy
b Department of Cardiology, S. Orsola-Malpighi Hospital, University of Bologna Medical School, Bologna, Italy
c Department of Anesthesiology, S. Orsola-Malpighi Hospital, University of Bologna Medical School, Bologna, Italy
Received 31 August 2003; received in revised form 10 March 2004; accepted 6 April 2004.
* Corresponding author. Tel.: +390-051-636-3361; fax: +39-051-345-990
e-mail: guidooppido{at}yahoo.com
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Abstract |
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 Top Abstract 1. Introduction2. Material and methods3. Results4. DiscussionAppendix A. Conference...References |
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Key Words: Congenital heart disease • Low birth weight • Cardio pulmonary by-pass • Cerebral protection
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1. Introduction |
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TopAbstract1. Introduction2. Material and methods3. Results4. DiscussionAppendix A. Conference...References |
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Continuous improvements in the management of premature or small for gestational age newborns, in the neonatology intensive care units, have considerably reduced the postnatal mortality of those babies; consequently, the request for surgical treatment of congenital heart lesions early in life in low weight babies, is expected to increase in the up-coming future.
However, although the outcome of neonatal cardiac surgery, has dramatically enhanced in the last two decades, low body weight itself still constitutes an important risk factor for morbidity and mortality [6–9].
Intensive medical therapy and continuous prostaglandin infusion for prolonged time, in those neonates who benefit ductus patency, may guarantee clinical stability with the rationale of delaying surgery letting babies gain weight. Nevertheless, this strategy seems not to be associated with a better outcome and furthermore it is not always practicable because of failure to thrive or permanent unstable hemodynamic conditions. Chang and colleagues [10] reported on a series of low birth weight and premature infants who were managed according to three different protocols: hospital survival rate was 82% in the complete repair group, 78% in the palliated group and 77% in the delayed surgery group, with an additional 10% mortality rate at the time of surgery for the latter.
Aim of the present study was to report on the outcome of the entire population of neonates and infants weighing less than 2500 g who underwent surgery other than ductus arteriosus closure at our institution in the last decade, with the intent of giving our contribution to the determination of the ideal treatment strategy in this challenging subgroup of babies.
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2. Material and methods |
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TopAbstract1. Introduction2. Material and methods3. Results4. DiscussionAppendix A. Conference...References |
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Follow-up data were obtained from our institution outpatient records and from our Catheterization Laboratory database. Each patient underwent clinical examination, chest X-ray and echocardiogram at 6–12 month regular intervals.
Study period was 10 years: from January 1993 to August 2002. Inclusion criterion was: body weight less then 2500 g at the time of surgery. Patients who underwent ductus arteriosus closure alone, as well as low birth weight or premature babies, who reached a body weight of more than 2500 g at the time of surgery, were not included in the study. End-point was in-hospital mortality (within 30 days after the operation).
2.1. Statistical analysis
Data are presented as mean±SD and range, unless otherwise specified.
Statistical significance in the research of risk factors for mortality, was determined with X2 test or Fisher's Exact analysis in the comparison of categorical variables and Student's t-test in the comparison of continuous variables. All variables that achieved P<0.2 in the univariate analysis were included in a multivariate model and examined by stepwise logistic regression. Significance was defined as P<0.05. Survival curves were obtained by Kaplan–Meier product limit method and compared with log rank test. Software used for statistical analysis was SPSS (Chicago, IL, USA) for Windows version 8.0.
2.2. Patient population
A total of 60 consecutive patients (33 females and 27 males), either neonates or infants, met the inclusion criteria in the study time period (Table 1)
. Twenty-seven (45%) were born prematurely: 1 before the 28th week of gestation, 7 between the 29th and 32nd, 19 between the 33rd and 36th. Thirty-three (55%) were full term low birth weight newborns (less than 2500 g at birth). Mean weight at birth was 2190±310 g.
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Prenatal cardiac diagnosis was available in 21 patients.
Thirty-seven patients were ductus dependent and were receiving prostaglandins, 10 were receiving high dose catecholamines infusion, five were permanently ventilated, three exhibited pulmonary complications in relation to prematurity, three developed metabolic acidosis requiring bicarbonates. None of the patients had intraventricular hemorrhage, necrotizing enterocolitis or sepsis.
Mean age at operation was 15.5±13.4 days (range 4–68 days) and mean weight was 2120±370 g (range 900–2500 g).
2.4. Diagnoses
Cardiac diagnoses included: coarctation complex (11 pts), transposition of great arteries (9 pts), interrupted or severely hypoplastic aortic arch 9, hypoplastic left heart syndrome 7, truncus arteriosus 5, double outlet right ventricle 4, tetralogy of Fallot 3, pulmonary atresia intact ventricular septum 4, double inlet left ventricle 3, ventricular septal defect 1, tricuspid atresia 1, multiple ventricular septal defects 1, complete atrio-ventricular septal defect 1, anomalous origin of the right pulmonary artery 1 (Table 2) .
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2.5. Surgery
Anesthetic protocols did not differ from those used in neonates with a body weight exceeding 2500 g and entailed: Fentanil 1–2 µg/kg/dose, Vecuronium 0.1–0.2 mg/kg/dose, Midazolam 50–100 µg/kg/dose and Sevofluorane.
Extracorporeal neonatal circuits sized 3/16–1/4 and were primed with irradiated and deleucocytised red blood cells and fresh frozen plasma, bicarbonates and heparin, achieving a hematocrit value of 30%. Aortic cannulation was performed with ‘number 20’ Teflon straight cannula (Sofracob s.a., Reventin Vaugris, France) which corresponds to a 1.5 mm internal diameter tip. Bicaval venous cannulation was performed entering the right atrium with two 12 F curve cannulas (Baxter International, Inc. San Diego, CA, USA); a single 20 F atrial venous cannula (Baxter International, Inc. San Diego, CA, USA) was preferred in all Norwood stage I operations. Oxygenators utilized from 1993 to 2000 were hollow fibers Masterflow D 701 (Dideco Modena, Italy) and from 2000 to date hollow fibers Lilliput D 901 (Dideco Modena, Italy). Intermittent blood cold cardioplegia was administered antegradely into the aortic root or coronary ostia. During cardio-pulmonary bypass, blood gas analysis was achieved using alpha-stat strategy. Pump flow was adjusted to maintain a blood pressure not above 40 mmHg and a mixed venous blood oxygen saturation, monitored continuously, never below 60–65%. Continuos ultrafiltration was carried out during cardio-pulmonary by-pass in each patient.
Forty-six patients underwent median sternotomy and 14 underwent left postero-lateral thoracotomy in the third or fourth intercostals space. Thirty-five (58%) patients were operated on cardio-pulmonary by-pass and 25 (42%) underwent off-pump procedures. Cardio-pulmonary by-pass and X-clamp mean times were 178±87 min and 74±53 min, respectively. Deep hypothermia (<18 °C) with circulatory arrest was avoided in all patients but 9, all of them operated on before 1996. In the anterior aortic arch surgery, cerebral selective perfusion technique, at a body temperature of 22–24 °C, was always preferred during the last 6 years.
Aortic arch surgery alone or as part of more complex procedures, was required in 32 cases (53%): anterior or entire arch reconstruction in 21, isthmus and posterior arch in 11. Anterior or entire arch reconstruction was part of more complex procedures in 13 cases: Norwood stage I operation 7, arterial switch operation 3, truncus arteriosus repair 2, aortico-pulmonary window 1. In eight cases anterior arch reconstruction was associated to: ventricular septal defect closure 4, left ventricular outflow tract obstruction release 2 pulmonary artery banding 2.
Each one of the 11 coarctation complex patients received repair of the coarctation and contemporarily enlargement of the posterior arch.
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3. Results |
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TopAbstract1. Introduction2. Material and methods3. Results4. DiscussionAppendix A. Conference...References |
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3.1. Early Mortality
Nine patients died in the early postoperative period, accounting for a hospital mortality of 15%. Causes of death included: heart failure in five patients, multiorgan failure in three, sepsis in one. At the univariate analysis (Table 4)
, weight at surgery (P=0.368), age (P=0.626), gestational age (P=0.144), type of surgery (correction or palliation) (P=1), use of cardiopulmonary by-pass (P=0.281), cerebral selective perfusion (P=0.38), associated non-cardiac malformations or syndromes (P=0.096) did not result to be risk factors for early mortality.
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Multivariate analysis by stepwise logistic regression (Table 4) indicated, as the only significant independent risk factor for early mortality, the use of deep hypothermia with circulatory arrest (P=0.002; CI 0.05–0.34; odds ratio [OR]=9.4), while a body weight less than 1500 g (when analyzed as a dichotomic variable) reached P value=0.06 (CI 0.13–1.7), with an odds ratio [OR]=3.5.
3.2. Complications
Among 46 interventions carried out via median sternotomy, sternum was left open in 15 patients; mostly just to prevent hemodynamic problems during the early postoperative period for the more complex surgical reconstructions.
The following complications occurred in 18 of the 51 early survivors: two patients were successfully resuscitated from cardiac arrest occurred in the day of surgery, nine developed low cardiac output requiring prolonged high dose inotropic support (dopamine and/or dobutamine>10 µg/kg/min, and/or adrenaline >0.1 µg/kg/min) and two of them needed a systemic-to-pulmonary shunt resizing few hours after the operation, six developed acute renal insufficiency, two had pulmonary hypertensive crisis requiring inhaled nitric oxide therapy and two had severe systemic postcoarctectomy hypertension, four acquired sepsis and were found positive to blood colture and successfully treated with selective antibiotic therapy, three patients required reintubation and prolonged mechanical ventilation for non-cardiac-related reasons: one had transitory phrenic nerve palsy, one disclosed tracheomalacia and one developed bilateral atelettasia.
All the patients were pre- and postoperatively routinely screened with cerebral echography by an experienced neonatologist in order to exclude the occurrence of brain damage at any time. Postoperative neurological complications were not observed in any patient.
3.3. Late mortality
Follow-up mean time was 48±33 months (range 2–123 months) and was 100% complete. Of the 51 early survivors nine patients died during the follow-up (late mortality 17.5%), three of them within six months from the operation. The following causes of death could be detected in all nine patients: one heart failure and one shunt thrombosis (both occurred within the sixth month after the operation, in patients waiting for Norwood stage II procedure), two severe pulmonary hypertension (one in a patient who received valve replacement for mitral valve stenosis and one in a patient who underwent pulmonary artery banding with a reabsorbable band), one pneumonia, one ab ingestis, one Duchenne muscular dystrophy, one patient died during cardiac reoperation in another hospital and one during esophageal reoperation.
Kaplan–Meier overall actuarial survival rate at 60 months was 70.0% (Fig. 1) . There was no significant difference (P=0.88) in survival between term and preterm patients (Fig. 2) (65.4 vs. 74.0%, respectively) or between babies who underwent repair in respect to those who had palliative procedures (Fig. 3) (74.7 vs. 64.6%, P=0.7).
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Four patients (8%) needed six reoperations for residual defects: subaortic stenosis resection two (both after interrupted aortic arch repair), mitral valve replacement two, mitral valve plasty one and residual ventricular septal defect closure one.
Two patients had homograft/heterograft replacement due to somatic overgrowth. The remaining 19 operations were part of staged univentricular repair (13) or delayed correction after palliation (6) and are reported in Table 5.
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4. Discussion |
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TopAbstract1. Introduction2. Material and methods3. Results4. DiscussionAppendix A. Conference...References |
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However, if compared with normal weight newborns undergoing cardiac surgery, low weight babies show an increased mortality [9,12]. On the other hand, deferring surgical treatment in order to achieve an increase in body size does not necessarily warrant an increase in survival [10]. Indeed, non-cardiac factors may be associated with low birth weight, and may jeopardize the outcome of surgery, thus requiring careful evaluation [9,12,13,14].
Our study population is composed by patients for whom, due to severely symptomatic cardiac lesions, a conservative approach by intensive medical treatment only, has been judge to be at higher risk in respect to a prompt surgical resolution. The overall 15% in-hospital mortality, comprising palliative and corrective procedures as well as complex cardiac malformations, shows that: an early surgical strategy may be highly rewarding in the treatment of this difficult group of patients. However, in our opinion this does not necessarily mean that every low-weight neonate should be aggressively treated by early surgery, unless intensive medical treatment is required because of severely symptomatic cardiac lesions.
Cardio-pulmonary bypass time, aortic cross-clamp time and the use of deep hypothermia with circulatory arrest were the only risk factors found at univariate analysis; whereas only the latter resulted as an independent variable associated with early mortality.
Prolonged by-pass and aortic cross-clamp time may not constitute risk factors themselves but could simply reflect the more complex type of surgical procedure.
Probably, a type II error should be taken into account for what concerns potentially important variables like: type of cardiac malformation, type of surgery (palliation vs. repair), use of cerebral selective perfusion, off-pump vs. on-pump procedures, prematurity or presence of associated non-cardiac malformations. Indeed, the 28% mortality of Norwood stage I procedures in our group was fairly higher in respect to the 0% of the patients who underwent repair of aortic coarctation. For the same reason, we have no statistical evidence of complete repair surgery to be at higher risk in respect to palliation, due to the limited number of patients and the relatively high heterogeneity of our study group, which entails palliative operations both as part of a staged monoventricular procedure as well as a bridge before complete biventricular repair.
Age at surgery has been reported by Reddy and coworkers (8) to be an important morbidity factor in low-weight infants. We did not find any correlation between age at surgery and surgical mortality (P=0.63).
Nineteen patients (32%) had associated non-cardiac malformations, the literature reporting a prevalence between 27 and 45% (2,4,6,10 and 15) with an ominous surgical outcome (14). The reduced significance of this variable in our analysis may be due to the low impact on the early postoperative period exerted by the low degree of malignancy of the types of extra cardiac malformations or syndromes found in our study group. Indeed, three patients died late after surgery (one patient with respiratory failure due to Duchenne muscular dystrophy and two other during non-cardiac surgery). Interestingly, bronco-pulmonary dysplasia and tracheo-bronchomalacia were a rare occurrence in our patients, with only one neonate requiring postoperative reintubation and prolonged mechanical ventilation. Similarly, necrotizing enterocolitis and intraventricular hemorrhage [15–17] were not detected in our patient population. Respiratory prematurity-related issues, such as jaline membrane disease, were present in three patients and required preoperative mechanical ventilation.
Routine preoperative and postoperative cerebral echographic evaluation allowed us to rule out major neurological complications, particularly intracranial bleeding.
Selective cerebral perfusion is our technique of choice for brain protection since 1996, and is currently used in all patients undergoing surgery of the anterior aortic arch.
While no definitive statement may be drawn from a limited experience in such a heterogeneous group of high risk patients, our study shows that primary complete repair may be achieved with an acceptable mortality (15.6% in our group), with no difference in respect to palliation in patients with anatomy potentially amenable to biventricular repair (20.0% in our group). Similarly, the 11.1% mortality of surgery in single ventricle-physiology shows that a definitive monoventricular palliation may be undertaken even in the setting of high risk low-weight neonates.
In conclusion, even thought the management of low birth weight and premature infants still represents a major challenge for all who take care of such patients, surgical treatment of their congenital malformations should be undertaken as soon as satisfactory hemodynamic stability and major organs recovery is achieved, with enhanced, but still acceptable early and mid-term morbidity and mortality.
4.1. Limits of our study
Limits of our study are certainly represented by the relatively small number of patients, and the nature of any retrospective study. In order to achieve a fair number of patients to be included into univariate and multivariate analysis, a decision was made to unify patients who underwent surgery with and without cardiopulmonary bypass, thus leading to a difficult interpretation of the statistical results and potential underestimation of potentially important variables. However, our study group represents a difficult and relatively rare type of patient with congenital heart disease, which deserves a multicentric study collecting a large number of cases.
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Footnotes |
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Appendix A. Conference discussion |
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TopAbstract1. Introduction2. Material and methods3. Results4. DiscussionAppendix A. Conference...References |
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Dr Oppido: These are 60 consecutive surgical patients. We did not collect all the babies who died before the operation or who were not referred for surgery because of major non-cardiac clinical issues. Moreover, we excluded all the premature and low birth weight babies for whom urgent surgery was not indicated, or who reached a body weight superior to 2500 grams at the time of surgery.
Therefore, our population is composed by 60 consecutive patients who needed urgent surgical treatment because of heart failure or some kind of ductus dependent congenital cardiac malformation.
Dr M. Pozzi (Liverpool, UK): Would you be able to point out a cutoff point in terms of weight with regards to seeing a difference in postoperative complication, and in particular, neurological complication?
Dr Oppido: All of our patients were routinely screened with brain ultrasound to rule out the presence of either preoperative or postoperative neurological complications, which were excluded in all cases.
Dr T. Bottio (Padova, Italy): Did you support any one of these patients with ECMO?
Dr Oppido: No, we did not.
Dr B. Maruszewski (Warsaw, Poland): Maybe I haven't noticed, but was one of your variables the date of the operation? Did the date of the operation influence the outcome that you studied?
Were patients operated earlier, for example, in your time span? Did they do better or worse? Was there any change depending on the date of the operation?
Dr Oppido: We know from the literature that the earlier those patients are operated the less complications seem to occur in the postoperative period. We did not observe this in our patient population. We rather believe that a major effort in order to stabilize the patient before surgery is warranted, regardless the time needed.
Dr Ebels: I don't think this is an answer to the question. The question is whether you performed better earlier in your experience or worse? Was there a learning curve?
Dr Oppido: Yes, there was a learning curve in our experience.
Dr Maruszewski: But was it one of the variables?
Dr Oppido: No it was not.
Dr R. Bartkowski (Poznan, Poland): Have you had any experience with hemofiltration or dialysis in this group of patients, renal failure or any problems?
Dr Oppido: Acute renal failure occurred in 6 patients, but none of them underwent any sort of hemofiltration or dialysis.
Dr F. Lacour-Gayet (Denver, CO, USA): I noticed in your analysis that deep circulatory arrest was a risk factor. My question to you is, do you avoid circulatory arrest and go to palliation or do you use full flow?
Dr Oppido: Deep hypothermia with circulatory arrest has been only adopted before 1996 and for the treatment of hypoplastic left heart syndrome or interrupted aortic arch, as it was for the 9 reported patients. Whereas, cerebral selective perfusion is the current technique of choice since 1996.
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References |
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TopAbstract1. Introduction2. Material and methods3. Results4. DiscussionAppendix A. Conference...References |
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