Simplified antegrade cerebral perfusion and myocardial protection during stage I Norwood procedure

Several important modifications have been introduced in the intraoperative management of neonates with hypoplastic left heart syndrome during first-stage palliation. Among these, utilization of selective antegrade cerebral perfusion and interposition of a conduit between the right ventricle and pulmonary artery are currently favored by many centers. We briefly describe our current approach to the modified stage I Norwood procedure.

Problems with the right ventricular outflow tract: a review of morphologic features and current therapeutic options

Repair of complex malformations that necessitate restoration of continuity between the right ventricle and the pulmonary arteries can now safely be performed with low morbidity and mortality. Major concerns still remain on the long-term outlook for these patients, and about the durability of the different prostheses used to restore that continuity, whether during initial correction or at the time of reintervention for failure of the conduit or pulmonary regurgitation. In this review, we discuss the salient morphologic features of the right ventricular outflow tract, and then focus on the indications for early and late intervention, current therapeutic options, and outcomes.

Implications of anomalous right subclavian artery in the repair of neonatal aortic coarctation

Spinal cord perfusion is predominantly from the anterior spinal artery, which arises from the vertebral arteries by way of the subclavian arteries. Anomalous origin of the right subclavian artery and coarctation of the aorta is considered to be an increased risk factor for spinal cord damage, possibly because of the minimal collateral circulation during aortic clamping. The aim of this study is to review 5 consecutive cases of neonatal aortic coarctation with ARSA.

METHODS

Five neonates (0.8 to 4.6 kg) underwent operation between July 1999 and December 2000 with resection of the coarctation and end-to-end anastomosis. Both subclavian arteries (n = 5) and left carotid artery (n = 4) were clamped, leaving the right carotid artery as the sole provider of perfusion for the spinal cord.

RESULTS

Despite clamping of both subclavian arteries, right radial artery pressure was measurable in 4 of the 5 cases. Aortic cross-clamp times varied from 12 to 26 minutes at a core temperature of 34 degrees to 35 degrees C. There was no operative mortality. None of the neonates developed any major neurologic sequelae.

CONCLUSIONS

When clamping the two subclavian arteries during coarctation repair, the spinal artery is left with collateral blood flow that can theoretically originate from the carotid arteries through the circle of Willis and retrogradely down the vertebral arteries. The presence of such collateral circulation was documented as recordable blood pressure in the right radial artery during surgical repair.

Right ventricular inflow obstruction from massive fungal vegetation presenting as neonatal circulatory collapse

Occurrence of neonatal circulatory collapse imposes effective differential diagnosis and expeditious therapeutic intervention. We report a case of neonatal cardiogenic shock, caused by a massive intra-cardiac fungal vegetation.

Management of pulmonary venous obstruction after correction of TAPVC: risk factors for adverse outcome

OBJECTIVE

Recurrent pulmonary venous obstruction (PVO) occurs in 0-18% of infants undergoing correction of total anomalous pulmonary venous connection (TAPVC). Limited published data suggest that PVO usually develops within 6 months of primary repair, and that outcomes of reoperations are poor. This study aimed to review our experience of reoperations for PVO post-TAPVC repair and to identify risk factors for adverse outcome.

METHODS

Twenty patients underwent reoperation for PVO between 1982 and 2002. Clinical data were reviewed. TAPVC was mostly infracardiac (11 patients). TAPVC was obstructed in nine patients. PVO developed early (<6 months) in seven patients, and late in 13 (>6 months). Time of presentation was unrelated to type of PVO (anastomotic vs. ostial). Repair was accomplished using various techniques (anastomotic enlargement with native atrial tissue, enlargement with pericardium, free or in situ, or other prosthetic material). Follow-up ranged from 1 month to 15 years (average 44 months).

RESULTS

Thirteen patients received one reoperation, while seven had multiple reoperations. In 13 patients, PVO was defined as new onset (no obstruction post-TAPVC repair), and in seven patients as residual (minimal obstructive changes post-TAPVC repair that progressed to PVO). Ten patients presented with anastomotic PVO, six with anastomotic and ostial PVO (involving the PVs), three with ostial PVO, and one with coronary sinus-left atrial junction stenosis. Mortality was 25% (5/20). Six of the ten patients with anastomotic PVO underwent one reoperation (2/6 died); the other four developed ostial PVO after reoperation, requiring multiple procedures (2/4 died). Mode of presentation (new onset vs. residual), site of obstruction (anastomotic vs. ostial), preoperative RV pressure (<0.8 vs. >0.8 systemic), number of reoperations (single vs. multiple), residual obstruction (presence or absence), and operative approach (Gore-tex or not) did not seem to affect outcomes. Risk factors for death were early presentation (<6 months) and persistence of pulmonary hypertension after reoperation; early presentation was also a risk factor for multiple reoperations.

CONCLUSIONS

Our findings support the conclusion that early presentation and postoperative pulmonary hypertension have the greatest adverse impact on outcome. Of these, failure to achieve a low-pressure pulmonary vascular system seems to be the variable that most strongly prevents survival. In our series, neither ostial PVO nor multiple re-interventions significantly increased surgical risk. The negative impact of postoperative residual obstruction on outcome was not striking. However, an aggressive surgical approach to this disease is still warranted. Although the role of each technique in obtaining long-lasting relief of PVO remains to be established, the use of artificial material seems unwise.

Optimal timing of the Ross procedure in the management of chronic aortic incompetence in the young

The appropriate timing of intervention in patients with chronic aortic incompetence allows recovery of ventricular function. We sought to determine the optimal timing of the Ross procedure for chronic aortic incompetence in young patients. We retrospectively analysed case notes, and measured pre- and postoperative echocardiographic indexes of left ventricular function, in patients who had undergone the Ross procedure for chronic aortic incompetence.

METHODS AND RESULTS

We found 21 patients with preoperative and postoperative data suitable for analysis. Their age at operation ranged from 5.6 to 26 years, with a median of 13.8 years, and the duration of follow-up was from 0.5 to 6.8 years, with a median of 2.4 years. The preoperative left ventricular end-diastolic dimension was converted to a z-score, and this was used as a threshold to divide the population. Using the threshold of a preoperative left ventricular z-score of more than 3 to divide the population did not show any difference in postoperative parameters of left ventricular function. Significant differences were found postoperatively, however, in both the left ventricular z-score and the ratio of left ventricular end-diastolic radius to posterior wall thickness in diastole, with a cutoff preoperative threshold z-score greater than 4.

CONCLUSION

The increase in the ratio of left ventricular end-diastolic radius to the thickness of the posterior wall in diastole would suggest that there is disruption of left ventricular short axis architecture and myocardial contractile function when intervention is postponed. The significantly larger left ventricular dimension at end-diastole, despite the reduction in volume loading post surgery, may also demonstrate irreversible structural changes. Our data would suggest that recovery of left ventricular function is less likely when the left ventricular z-score has reached the value of 4, and that, ideally, intervention should be performed when the z-score approaches or exceeds 3.

Closure of recurrent VSD due to dehiscence of calcified patch

Closure of residual ventricular septal defects may be extremely difficult in the presence of severe calcification of a previous patch. Removal of such calcification carries a risk of damaging the aortic and tricuspid valve as well as the conduction system. We describe a novel technique for closure of such a defect placing a new patch over and around the calcified one in an 18-year-old patient who had undergone initial surgery 12 years ago.

Hybrid approaches to complex congenital cardiac surgery

OBJECTIVES

A hybrid operation is a joint procedure involving the interventional cardiologist and the cardiac surgeon concomitantly to optimise surgical management. The aim of our study was to demonstrate the conceptual development and the feasibility of a hybrid approach to complex congenital cardiac surgery.

METHODS

Descriptive study of two different indications for concomitant intervention by the cardiologist and the cardiac surgeon. Seven patients with complex congenital heart defects requiring high risk operative interventions were included in the study. The indications were: (1) intraoperative stenting of a pulmonary artery stenosis with concomitant additional surgical procedures (n=4). (2) Balloon occlusion of Blalock-Taussig shunts or major aorto-pulmonary collateral artery to control pulmonary blood flow during surgical repair (n=3).

RESULTS

All patients had successful hybrid procedures. There were no important complications related to the temporal proximity of the interventional procedure and cardiac surgery, the latter being significantly facilitated by the former.

CONCLUSIONS

Intraoperative stenting of pulmonary artery stenosis with additional surgical repair and balloon occlusion on cardiopulmonary bypass can be performed safely and may be complementary in patients with complex lesions by providing a better result in combination than either alone can offer.

Surgical substrates of postoperative junctional ectopic tachycardia in congenital heart defects

BACKGROUND

Junctional ectopic tachycardia is a major cause of postoperative morbidity after surgery for congenital cardiac disease. To elucidate the mechanism of junctional ectopic tachycardia, surgical correlations were studied in four types of congenital heart defects involving closure of a ventricular septal defect, relief of right ventricular outflow tract obstruction, or both.

METHODS

Between 1997 and 1999, a total of 343 consecutive patients underwent repair of tetralogy of Fallot (n = 114), common truncus arteriosus (n = 10), ventricular septal defect (n = 161), and atrioventricular septal defect (n = 58). Variables studied included demographic and bypass data, surgical approaches toward ventricular septal defect closure and relief of right ventricular outflow tract obstruction, and resection as opposed to division of muscle bundles.

RESULTS

Junctional ectopic tachycardia occurred most frequently after repair of tetralogy of Fallot (n = 25; 21.9%), with no cases occurring after repair of common trunk, 6 occurring after repair of ventricular septal defect (3.7%), and 6 occurring after repair of atrioventricular septal defect (10.3%). Stepwise logistic regression revealed that resection of muscle bundles (P <.0001), higher bypass temperatures (P <.03), and relief of right ventricular outflow tract obstruction through the right atrium (P <.05) significantly and independently predicted postoperative junctional ectopic tachycardia.

CONCLUSIONS

Relief of right ventricular outflow tract obstruction appears to be more important in the causation of junctional ectopic tachycardia than does ventricular septal defect closure, which may explain the higher incidence of this complication after tetralogy of Fallot repair. Muscular resection seems to be more arrhythmogenic than is simple division. Increased traction through the right atrium for relief of right ventricular outflow tract obstruction would fit the hypothesis that enhanced automaticity of the His bundle, the morphologic substrate for junctional ectopic tachycardia, may result from direct trauma or infiltrative hemorrhage of the conduction system. When feasible, techniques avoiding both extensive muscle resection and excessive traction should be applied during resection of right ventricular outflow tract obstruction.

Surgical repair of supposedly multiple defects within the apical part of the muscular ventricular septum

BACKGROUND

A distinct defect has been described within the apical part of the muscular ventricular septum, which has multiple orifices when seen from its right ventricular aspect. Closure has been suggested using umbrella devices introduced on a catheter. Such an intervention, however, can be technically difficult in small infants.

METHODS

We have recently seen two examples of this type of complex communication between the apexes of both left and right ventricles. Neither could be closed by catheterization. A surgical approach was used through a modified apical right ventriculotomy. We have also studied two autopsied specimens, which clarify the morphologic arrangement.

RESULTS

Both patients were closed successfully, with trivial residual shunt and good biventricular functions. The patients were clinically well at 2-year follow-up.

CONCLUSIONS

Surgical division of right ventricular trabeculations makes it feasible to identify and repair the septal deficiency, which is a solitary hole. On the basis of our morphologic study, we offer an explanation for the anatomic arrangement that differs from the one proposed by recent previous investigators. If the ventricular incision is appropriately placed, our anatomic studies suggest that it is possible to visualize the solitary opening from its right ventricular aspect, and achieve surgical closure with a single patch.

Intravenous magnesium in experimental stent thrombosis in swine

We investigated the effects of magnesium on acute platelet-dependent stent thrombosis in an ex vivo porcine arteriovenous shunt model of high-shear blood flow. Control nitinol stents were expanded to 2 mm in diameter in a tubular perfusion chamber interposed in the shunt and exposed to flowing arterial blood at a shear rate of 2100 s(-1) for 20 minutes (n=156 perfusion runs in 10 swine). Animals were treated with intravenous heparin or MgSO(4) alone (2 g bolus over 20 minutes, followed by 2 g/h infusion) and combined heparin plus MgSO(4) in random fashion. Effects on thrombus weight (TW), platelet aggregation, bleeding time, activated clotting time, mean arterial blood pressure, and heart rate were quantified. Data points in the magnesium-treated animals were examined within 20 minutes after bolus (Mg-early) and >40 minutes after bolus (Mg-late). Stent TW (20+/-3 mg, pretreatment) was reduced by 42+/-21%, 47+/-19%, 48+/-16%, 67+/-12%, and 86+/-8% in the groups treated with Mg-early alone, Mg-late alone, heparin alone, heparin+Mg-early, and heparin+Mg-late, respectively (all P<0.001 versus pretreatment, P<0.001 for heparin+Mg-early and Mg-late versus heparin or magnesium alone, and P<0.05 for heparin+Mg-late versus heparin+Mg-early, ANOVA). Magnesium had no significant effect on platelet aggregation, activated clotting time, or bleeding time. There were no significant effects on heart rate or mean arterial blood pressure. The serum magnesium level was inversely correlated with TW (r=-0.70, P=0.002). In conclusion, treatment with intravenous MgSO(4) produced a time-dependent inhibition of acute stent thrombosis under high-shear flow conditions without any hemostatic or significant hemodynamic complications. Thus, magnesium may be an effective agent for preventing stent thrombosis.

Traumatic disruption of the ascending aorta in a child after heart transplant

We report a traumatic disruption of the ascending aorta in an 8-year-old boy who had undergone orthotopic cardiac transplant at 6.5 years of age for congenital heart block and dilated cardiomyopathy. At presentation his aortic injury was not immediately recognized, but persistence in identifying and confirming a suspicious aortic rupture was lifesaving.

A case for anatomic correction in atrioventricular discordance? Effects of surgery on tricuspid valve function

OBJECTIVE

To assess tricuspid valve function in atrioventricular discordance after palliative procedures (pulmonary artery banding and Blalock-Taussig shunt) and corrective procedures (anatomic and physiologic repair).

METHODS

Tricuspid valve dysfunction was assessed by transthoracic echocardiography and graded as no regurgitation (0), mild (1), moderate (2), and severe (3) before and after palliative and corrective procedures performed in 97 patients with atrioventricular discordance between 1988 and 1999. Thirty-two percent had an isolated ventricular septal defect, 43% had a ventricular septal defect and pulmonary stenosis, and 16% had pulmonary stenosis. Twenty-six patients underwent pulmonary artery banding and 28 had a Blalock-Taussig shunt. Seventy patients underwent physiologic and 19 underwent anatomic repair. Six patients underwent one-ventricle repair.

RESULTS

After pulmonary artery banding, the tricuspid regurgitation score decreased from 1.7 +/- 0.8 to 0.9 +/- 0.6 (P <.001). In patients who underwent a Blalock-Taussig shunt, the tricuspid regurgitation score increased from 0.7 +/- 0.5 preoperatively to 1.4 +/- 0.6 postoperatively (P <.001). After physiologic repair, there was no significant change in the tricuspid regurgitation score; however, 7 patients required additional repair or replacement. The regurgitation score was significantly reduced from 1.5 +/- 0.8 to 0.4 +/- 0.5 (P <.001) after anatomic repair. The operative mortality in patients who underwent physiologic repair was 7% as compared with 0% in the anatomic repair group (P =.59). The median follow-up was 3.2 years.

CONCLUSIONS

Right ventricular volume loading (shunt) worsens tricuspid regurgitation, whereas volume reduction (banding) or left-to-right septal shift (anatomic repair) has beneficial effects. We have not observed a significant change in the tricuspid regurgitation score after physiologic repair. Anatomic repair can be performed in selected patients with atrioventricular discordance and provides superior functional results.

The effect of prelung transplant clinical status on post-transplant survival of children with cystic fibrosis

The aim of this study was to determine whether transplanting paediatric cystic fibrosis (CF) patients later in the course of their disease was detrimental to their post-transplant survival. Data was collected from 51 children with CF undergoing lung or heart-lung transplantation May 1988-March 1999. The following risk factors were tested by Cox proportional hazards modelling: age at transplant; sex; donor/recipient sex mismatch; donor/recipient cytomegalovirus (CMV) mismatch; cold and warm graft ischaemic times; and donor age. Pretransplant forced expiratory volume in one second (FEV1), minimum oxygen saturation obtained during 12 min walk (Sa,O2min), and a survival probability score (SP) calculated from FEV1, age adjusted resting heart rate, age, sex, blood haemoglobin (Hb), and serum albumin were then added to the model. None of the risk factors were significantly correlated with death during the study period. No evidence that clinical status prior to transplant has any effect upon the post-transplant survival of children with cystic fibrosis was found.

Intrapulmonary arteriovenous shunting may be a universal phenomenon in patients with the superior cavopulmonary anastomosis: a radionuclide study

OBJECTIVE

To evaluate the extent of intrapulmonary right to left shunting in children after bidirectional cavopulmonary anastomosis (BCPA).

DESIGN

Prospective study of patients who underwent BCPA in a single centre.

PATIENTS

17 patients with complex cyanotic congenital cardiac malformations who underwent BCPA at 1-45 months of age (median 21 months) were evaluated 15-64 months postoperatively (median 32 months). Five children between 1 and 10 years (median 5 years) with normal or surgically corrected intracardiac anatomy and peripheral pulmonary circulation who required V/Q scanning for other reasons were used as controls.

INTERVENTIONS

All patients underwent cardiac catheterisation to exclude angiographically demonstrable venovenous collaterals followed by pulmonary perfusion scanning using (99m)technetium ((99m)Tc) labelled albumen microspheres to quantify the intrapulmonary right to left shunt.

MAIN OUTCOME MEASURE

Percentage of intrapulmonary right to left shunt.

RESULTS

The mean (SD) level of physiological right to left shunting found in the control group was 5.4 (2.3)%. All patients with BCPA showed the presence of a significantly higher level of intrapulmonary shunting (26.8 (16.9)%, p < 0.001). The degree of shunting was significantly increased in the subgroup of 11 patients with BCPA as the only source of pulmonary blood flow (34.9 (15.8)%), when compared to the six remaining patients with an additional source of pulmonary blood supply (12.0 (2.6)%, p < 0.001). There was a negative correlation between age at BCPA and the shunt percentage found in the patients with a competitive source of pulmonary blood flow (r = -0.63, p < 0. 01).

CONCLUSIONS

Intrapulmonary right to left shunting develops in all patients following BCPA. This may be caused by a sustained and inappropriate vasodilatation resulting from absence or decreased levels of a substance that inhibits pulmonary vasodilatation. Augmenting BCPA with an additional source of blood flow containing hepatic factor limits the degree of intrapulmonary arteriovenous shunting and may help provide successful longer term palliation.

Management of congenital tracheal stenosis: a multidisciplinary approach

Congenital tracheal stenosis is a rare but underdiagnosed anomaly which can present as life-threatening respiratory insufficiency in neonates and infants. Initial control of the airway is mandatory. Surgical correction is the mainstay of therapy and is achieved with low mortality. The type and extent of repair depends largely on the length of stenosis. Cardiac anomalies are frequently associated and may be addressed at the time of tracheal surgery. Despite initial satisfactory results, post-operative morbidity due to persistent granulation tissue is substantial. It is through a multidisciplinary approach and close follow-up of the repaired airway that these demanding patients are best cared for. The long-term quality of life remains uncertain.

Replacement of the proximal aorta and aortic valve using a composite bileaflet prosthesis and gelatin-impregnated polyester graft (Carbo-Seal): early results in 143 patients

OBJECTIVE

We report the combined early results from two centers in the United Kingdom using a composite conduit consisting of a bileaflet mechanical valve incorporated into a gelatin-impregnated, ultra-low porosity, woven polyester graft (Carbo-Seal; Sulzer Carbomedics, Inc, Austin, Tex).

METHODS

Between August 1992 and March 1997, 143 patients underwent aortic root replacement with the Carbo-Seal composite prosthesis. The indication for surgery was acute type A dissection in 31 (22%), chronic type A dissection in 9 (6%), ascending aortic aneurysm without dissection in 100 (70%), and false aneurysm of the ascending aorta in 3 (2%). Twenty-seven patients (19%) had undergone previous sternotomy, and 40 (28%) were seen as emergencies. Concomitant procedures were performed in 38 (27%), including 18 aortic arch or hemiarch replacements. Total follow-up is 270 patient-years. Follow-up is 100% complete.

RESULTS

The early (30-day) mortality was 7% (10 patients). Permanent neurologic events occurred in 2%. At a mean follow-up of 23 months, 94% of survivors were in New York Heart Association functional class I. Freedom from reoperation was 97.2% +/- 1.6% (1 standard error [1 SE]) at 12 months and 95.7% +/- 2.2% at 48 months. Including early mortality, survival was 90.1% +/- 2.6% at 12 months and 83.1% +/- 3. 5% at 48 months.

CONCLUSIONS

Aortic root replacement with use of the Carbo-Seal prosthesis can be undertaken with a relatively low early mortality and morbidity. A low reoperation rate and high intermediate-term survival can be expected, but continued follow-up is needed to determine the long-term efficacy of this prosthesis.

Lung transplantation and life extension in children with cystic fibrosis

BACKGROUND

Lung transplantation has been available as therapy for end-stage lung disease since the early 1980s, but survival after transplantation remains poor, with continued controversy as to the survival benefit from the procedure. We examined the effect of lung or heart-lung transplantation on the survival of a cohort of children with cystic fibrosis and severe lung disease.

METHODS

Between May, 1988, and May, 1998, 124 children with cystic fibrosis were accepted for lung transplantation. 47 received transplants, 68 died while they awaited organs, and nine remained on the active waiting list. We constructed a proportional-hazards model that used variables of prognostic significance in this population. By including transplant status as a time-dependent covariate, we were able to calculate a hazard ratio for transplantation. Date of entry into the study was the date when children were added to the list for transplantation, and measurements were taken at this time. Children were accepted for transplantation if they had a life expectancy of 2 years or less, a poor quality of life, and no contraindications to transplantation.

FINDINGS

After 1 year, 35 (74%) children were still alive; after 5 years 12 (33%) children were alive. The univariate hazard ratio for transplantation was 0.41 (95% CI 0.23-0.74; p=0.003). Transplantation remained significantly associated with survival after correction for differences in age, sex, height-corrected forced expiratory volume in 1 s, minimum oxygen saturation during a 12 min walk, haemoglobin concentration, albumin concentration, and age-corrected resting heart rate (hazard ratio 0.31 [0.13-0.72]; p=0.007).

INTERPRETATION

If centres follow our criteria for accepting patients for transplantation, and achieve similar survival after transplantation, they could expect a survival benefit for their patients in line with our results.

Common arterial trunk associated with double aortic arch

The combination of common arterial trunk associated with double aortic arch is very rare. We are aware of only four cases ever reported in English literature. We add two cases of this entity and comment on the morphological aspects, the clinical impact of the combined lesions, and their diagnostic and therapeutic implications.

Long-term results of valve replacement using antibiotic-sterilised homografts in the aortic position

OBJECTIVE

Antibiotic-sterilised homograft valves stored at 4 degrees C have been implanted in the subcoronary position in this unit since 1973. This study was undertaken in order to assess the long-term function of these valves.

METHODS

All 249 patients undergoing homograft aortic valve replacement (AVR) at the Wessex Cardiothoracic Centre between April 1973 and December 1994 were studied. Homograft valve sizes ranged from 15 mm to 28 mm internal diameter, 202 (81.1%) varying between 18 mm and 22 mm. The mean patient follow-up was 12.4 years with a total follow-up of 3096 patient-years. There were six early deaths (2.4%).

RESULTS

On actuarial analysis, survival was 78.5+/-2.7% (1SE) at 10 years, 65.7+/-3.3% at 15 years and 55.0+/-3.9% at 20 years. The freedom from redo AVR was 87.9+/-2.4% at 10 years, 71.7 +/-3.8% at 15 years and 49.7+/-5.6% at 20 years. The freedom from structural degeneration was 85.6+/-2.5% at 10 years, 63.6+/-4.0% at 15 years and 41.9+/-6.4% at 20 years. On multivariate analysis the risk of valve failure was significantly higher in younger patients (P<0.0001) and in those who underwent aortic root tailoring (P = 0.024). The freedom from endocarditis was 98.4+/-0.9% at 10 years, 96.2+/-1.6% at 15 years and 95.1+/-1.9% at 20 years. Of the 249 patients, 218 had an isolated homograft AVR and were not anticoagulated. In this group there were two possible thromboembolic events.

CONCLUSION

As well as the established haemodynamic benefits, this study has shown that homograft AVR with antibiotic-sterilised 4 degrees C stored homograft valves implanted in the subcoronary position, offers good long-term results.

Successful innominate thromboembolectomy of a paradoxic embolus

A 54 year-old man had symptoms of acute right hemispheric cerebral ischemia. He was initially considered for participation in a trial of early thrombolysis in stroke, but an innominate artery embolus was found with no apparent arterial source. The embolus was removed by means of a combined brachial and carotid bifurcation approach to protect the cerebral vasculature from embolic fragmentation during extraction. Further investigation revealed deep venous thrombosis, evidence of pulmonary emboli, and a patent foramen ovale, supporting a diagnosis of paradoxic embolus. Additional treatment included anticoagulation and placement of an inferior vena caval filter. The unusual condition of paradoxic embolus is reviewed, and the management of this patient is discussed.

Endocarditis as the first presentation of AIDS in infancy

A two month old Ugandan boy underwent surgery for an obstructive right ventricular vegetation associated with disseminated Staphylococcus aureus infection. Both the child and his mother subsequently tested positive for HIV infection. Very little is know about the incidence of endocarditis in paediatric patients with AIDS. To our knowledge this is the first case reported of disseminated S aureus infection associated with endocarditis and an obstructing vegetation in an HIV positive infant with a structurally normal heart. The initial signs and symptoms for endocarditis were atypical, a reflection of the overwhelming infection in an immunocompromised patient. Severe infections may have an atypical presentation in immunosuppressed patients. AIDS needs to be considered in these patients, especially if they come from populations with endemic HIV infection.

When is extracorporeal life support worthwhile following repair of congenital heart disease in children?

BACKGROUND

Although the use of extracorporeal life support (ECLS) following repair of congenital heart defects in children is increasing, the criteria for ECLS usage in these patients is not well defined. The overall survival of such patients is disappointingly low and may depend on both the indication for support and the time at which ECLS is commenced.

METHODS

Between January 1993 and December 1996, 727 children underwent surgery for congenital heart defects at our institution with an overall hospital mortality of 5.8% (42 children). Nine of these children were treated with ECLS postoperatively. There were seven males and two females with a mean age of 7.2 months (range 2 weeks-3 years). Seven children could not be weaned from cardiopulmonary bypass (CPB) in the operating theatre. A further two were treated with ECLS later on during the postoperative period (commenced at 14 and 48 h). Full veno-arterial extra corporeal membrane oxygenation (ECMO) support was used in all children except one in whom a left ventricular assist device (LVAD) was used.

RESULTS

The median duration of support was 121 h (range 15-648 h). Four children (44%) were weaned from support and two of these are long-term survivors. Of the seven children in whom ECLS was instituted because of failure to wean from CPB, there was one long term survivor (LVAD support). Of the two patients in whom ECLS was instituted during the post-operative period there is one long-term survivor.

CONCLUSIONS

Weaning form ECLS and decannulation in 44% of our patients is comparable to other series of post-cardiotomy patients requiring ECLS. However, full veno-arterial ECMO instituted because of a failure to wean from CPB during corrective surgery is associated with an extremely poor outcome (zero long-term survivors in six patients).

Cerebral oxygenation during paediatric cardiac surgery: identification of vulnerable periods using near infrared spectroscopy

OBJECTIVE

Neurologic sequelae remain a well recognised complication of paediatric cardiac surgery. Monitoring of cerebral oxygenation may be a useful technique for identifying vulnerable periods for the development of neurologic injury. We sought to measure regional cerebral oxygenation in children undergoing cardiac surgery using near infrared spectroscopy to ascertain such vulnerable periods.

METHODS

Observational study of 18 children (median age 1.3 years) undergoing cardiac surgery (17 with cardiopulmonary bypass, 8 with circulatory arrest). Regional cerebral oxygenation was monitored using the INVOS 3100 cerebral oximeter and related to haemodynamic parameters at each stage of the procedure.

RESULTS

Prior to the onset of bypass, 10 patients had a decrease in regional cerebral oxygenation of > or = 15% points, reaching an absolute haemoglobin saturation less than 35% in 5 cases. The most common cause was handling and dissection around the heart prior to and during caval cannulation. With institution of bypass, regional cerebral oxygenation increased by a mean 18% points to a mean maximum of 75%. During circulatory arrest regional cerebral oxygenation decreased with rate of decay influenced by temperature at onset of arrest (0.25%/min at < 20 degrees C; 2%/min at > 20 degrees C). Reperfusion caused an immediate increase in regional cerebral oxygenation followed by a decrease during rewarming. Discontinuation of bypass caused a precipitous decrease in regional cerebral oxygenation in 5 patients, reaching less than 50% in 3 patients.

CONCLUSIONS

These observations suggest that the pre- and early post-bypass periods are vulnerable times for provision of adequate cerebral oxygenation. Near infrared spectroscopy is a promising tool for monitoring O2 supply/demand relationships especially during circulatory arrest.

Surgical treatment of acquired ventricular septal defects in the elderly

OBJECTIVE

As the population continues to age, older patients are being referred for repair of acquired ventricular septal defect (VSD) following myocardial infarction (MI). The purpose of this study was to assess the effect of age (> or = 70 years) on operative risk and long term survival following repair of an acquired VSD.

METHODS

Between January 1972 and December 1995, 179 patients have undergone repair of acquired VSDs following MI in our unit. There were 118 males and 61 females (age range 43-80 years) of whom 60 were aged 70 years or above.

RESULTS

The overall early mortality was 27%. On univariate analysis risk factors for early death included shorter time from both MI and detection of murmur to operation (P < 0.01, P = 0.04), site of MI (P < 0.01), higher NYHA class (P < 0.01), lower preoperative blood pressure (P < 0.01) and longer cardiopulmonary bypass and cross clamp times (P < 0.01, P = 0.03). Non significant variables included age, sex, concomitant CABG and preoperative renal function. Early mortality was 28.6% (34/119) in patients under 70 and 25.0% (15/60) in those over 70. This difference was not significant. The only significant differences between the age groups were sex distribution (females > males, P < 0.01), in the older group, and shorter time from both MI and detection of murmur to operation (P = 0.04, P = 0.02). Cardiopulmonary bypass was the only statistically significant variable on multivariate analysis (P = 0.01).

CONCLUSIONS

There was no significant difference in early mortality between the two age groups. As shorter times from both MI and detection of murmur to operation adversely affect early mortality, age over 70 years should not be used to determine suitability for surgery.

Prospective study of the value of necropsy examination in early death after cardiac surgery

OBJECTIVE

To assess the value of necropsy examination in patients dying soon after cardiac surgery, particularly the proportion of clinical questions answered by the necropsy, the frequency of major unexpected findings, and the limitations of the procedure.

DESIGN

A three year prospective study of necropsy examinations in adult patients dying before discharge or within 30 days of cardiac surgery performed under cardiopulmonary bypass in one hospital.

SETTING

Tertiary referral centre.

RESULTS

123 of 2781 patients (4.4%) died in the early postoperative period, and necropsy examination was performed in 108 of these (88%). The mortality after emergency procedures (18%) was much higher than after routine operations (2.6%). The main causes of death were cardiac failure (52%), haemorrhage (14%), cerebral disease (6%), and pulmonary emboli (5%). The necropsy changed the stated cause of death in 16 patients (15%), and answered clinical questions in 24 of 38 patients. In 15 patients necropsy examination did not provide a full explanation of death. Most of these patients died of cardiac failure soon after surgery or were sudden unexpected deaths.

CONCLUSIONS

Necropsy examination in patients dying early after cardiac surgery is valuable as it answers the majority of clinical questions, and shows unexpected findings in a significant proportion of cases.

Bloodless open-heart surgery in infants and children

Between October 1984 and January 1993, seven children of Jehovah's Witnesses underwent corrective open-heart surgery for congenital defects, on cardiopulmonary bypass (CPB). Age at surgery ranged from three months to 6.5 years, and weight ranged from 4.2 kg to 23.2 kg, with two children weighing less than 10 kg. The principal cardiac anomalies were tetralogy of Fallot (two), double outlet right ventricle (one), subaortic stenosis (one), transposition of the great arteries and ventricular septal defect (one), atrial septal defect and congenital heart block (one), and congenital mitral regurgitation (one). Hypothermic CPB was used in all seven operations with crystalloid priming of the extracorporeal circuit. CPB was based on our standard perfusion protocols. All surgical procedures were done without the use of blood or blood products. The mean preoperative haematocrit (Hct) was 40.9% (range 31.0-47.8%). The mean lowest intraoperative Hct was 17.3% (range 15.0-24.3%), whereas the immediate post-CPB Hct was 19.6% (range 15.3-24.0%). The Hct progressively increased to 29.2% (range 21.0-34.2%) on the first postoperative day, and 32.3% (range 24.2-38.3%) at the time of discharge. There was no hospital mortality, and the mean hospital stay was 10 days (8-13 days). We report the safe repair of complex open-heart surgery in children, without blood transfusion, even in small infants. The successful management of these patients requires meticulous attention to surgical and perfusion technique, and sound postoperative management.

Cyclosporin pharmacokinetics in heart-lung transplant recipients with cystic fibrosis. Effects of pancreatic enzymes and ranitidine

Cyclosporin (CsA) is currently the main immunosuppressive agent used in organ transplantation with considerable improvement in graft survival. Oral CsA solution is highly lipophilic, and its bioavailability may be reduced in cystic fibrosis (CF) heart-lung transplant recipients with pancreatic, gastrointestinal, and hepatic insufficiency. The bioavailability of oral CsA solution in 7 CF transplant recipients (5 male and 2 female with a mean age of 27 years and a mean weight of 49 kg) and 3 non-CF heart-lung recipients (1 male and 2 female with a mean age of 41 years and a mean weight of 60 kg) was studied. Following intravenous CsA administration, the kinetic curves were similar with no significant difference in the volume of distribution and clearance of CsA demonstrated between the CF and non-CF groups. The mean daily dose of oral CsA in 7 CF subjects (23.3 mg.kg-1) was significantly higher than the 3 non-CF heart-lung recipients (4.8 mg.kg-1). The mean maximum blood concentration of CsA for the oral dose was 776 ng.ml-1 for the 7 CF subjects, which was comparable with the mean peak values of 789 ng.ml-1 for the 3 non-CF control subjects. Poor enteral absorption of CsA probably accounts for the significantly lower mean bioavailability in the 7 CF subjects (14.9%) compared with the 3 non-CF control subjects (39.4%). The effects on the bioavailability of oral CsA solution by pancreatic enzymes (Creon) and histamine-2 antagonist (ranitidine) were also evaluated in the 7 CF subjects. No significant difference was demonstrated.

Surgical management of Marfan syndrome in children

Between August 1983 and January 1991, seven patients with Marfan syndrome underwent surgery for severe cardiovascular complications. The mean age at presentation was 5.7 months (range 4 to 9 months) in the infant group (n = 3), and 13.3 years (range 10 to 16 years) in a group of older children (n = 4). The primary indications for surgery in the infant group (performed at a mean of 3 years after diagnosis) were ascending aortic aneurysm with valvar regurgitation in one patient, and severe mitral valve prolapse with regurgitation in two. In the older group, surgical indications (performed at a mean of 2.8 years after diagnosis) were ascending aortic aneurysm with valvar regurgitation in three patients and acute aortic dissection in one. For aortic surgery, a composite valved conduit was used in four patients, and an aortic homograft in one. For mitral valve surgery, mechanical prostheses were used. All patients survived the primary operation. Over a mean follow-up of 17.5 patient-years (range 1 to 9 years), two patients in the infant Marfan group went on to further successful surgery (prosthetic mitral valve replacement and aortic root repair with aortic homograft) at a mean interval of 4.3 years after the initial surgery. Our results suggest that the major cardiovascular risk factors of Marfan syndrome in the young, even in those diagnosed during infancy, have been favorably changed by surgery with an encouraging medium-term outlook. The correct timing of surgery is aided by echocardiography.

In vitro bioelectric properties of bronchial epithelium from transplanted lungs in recipients with cystic fibrosis

BACKGROUND--Bronchial epithelial function after heart-lung transplantation (HLT) for cystic fibrosis (CF) may be affected by the original disease as well as other factors such as prolonged organ ischaemic time, the interruption of bronchial arterial and lymphatic supply, infection, rejection, and cyclosporin. In vitro measurement of the bioelectric properties of the bronchial mucosal lining may be an effective means of characterising the mucosal function of the lung allografts in response to pharmacological agents. METHODS--Bronchial mucosal tissues from explanted native lungs of CF and non-CF patients at transplantation were used to assess the possible application of a mini-Ussing chamber. With this technique, the bioelectric responses of bronchial mucosal biopsies from six patients with CF, one patient with congenital heart disease, four with primary pulmonary hypertension, and one with emphysema, all after HLT, were studied. The bioelectric and pharmacological responses of biopsies of bronchial mucosa from patients after HLT were compared with biopsies from non-CF non-HLT subjects. RESULTS--The altered bioelectric properties of CF tissues could be detected by the mini-Ussing chamber technique. The basal bioelectric values and the responses to amiloride and isoprenaline in CF patients were not different from those in non-CF patients two years after HLT. No significant difference in the basal bioelectric properties and responses to amiloride and isoprenaline was found between HLT recipients and non-CF non-HLT subjects. CONCLUSIONS--The mini-Ussing chamber is an effective means of characterising the typical CF bioelectric defect which was not found in the transplanted lungs of CF patients up to two years after HLT. Furthermore, values were unaltered in comparison with non-transplanted lungs, suggesting that bronchial epithelial function is maintained after HLT.

Non-invasive mechanical ventilation for cystic fibrosis patients--a potential bridge to transplantation

The case histories of six cystic fibrosis patients awaiting heart-lung transplantation are reviewed. They all deteriorated with severe hypoxia and hypercapnia before donor organs became available. Nasal intermittent positive pressure ventilation was used in preference to conventional ventilation with excellent results in four patients. There were no episodes of hypotension or toxaemia and the patients were in a stable condition at the time of surgery and made an excellent post-operative recovery. The patients who were transplanted and the patient who died, for whom suitable donor organs did not become available, probably had a more comfortable time than they would have done if treated with conventional ventilation. This method of ventilation appears to be a useful bridge to transplantation when a patient suddenly deteriorates. It gives them a chance of survival for a few more days or even weeks during which time an urgent search for donor organs can be made. This is also a very cost effective method of ventilation and does not encroach on conventional Intensive Care Unit (ICU) facilities.

Non-invasive mechanical ventilation for cystic fibrosis patients--a potential bridge to transplantation

The case histories of six cystic fibrosis patients awaiting heart-lung transplantation are reviewed. They all deteriorated with severe hypoxia and hypercapnia before donor organs became available. Nasal intermittent positive pressure ventilation was used in preference to conventional ventilation with excellent results in four patients. There were no episodes of hypotension or toxaemia and the patients were in a stable condition at the time of surgery and made an excellent post-operative recovery. The patients who were transplanted and the patient who died, for whom suitable donor organs did not become available, probably had a more comfortable time than they would have done if treated with conventional ventilation. This method of ventilation appears to be a useful bridge to transplantation when a patient suddenly deteriorates. It gives them a chance of survival for a few more days or even weeks during which time an urgent search for donor organs can be made. This is also a very cost effective method of ventilation and does not encroach on conventional Intensive Care Unit (ICU) facilities.