Digital video recording of congenital heart operations with "surgical eye"

We describe our experience with routine digital video recording of congenital heart operations. We currently use the "surgical eye," in which a small camera is mounted between the standard surgical loupe lenses. This technique has evolved during the years of experience with various other techniques. We believe this is a good method for accurate definition of intracardiac anatomy that closely resembles the surgeon's view. This arrangement is economical and invaluable in training. This method of recording has been used in more than 1,000 operations.

The World Society for Pediatric and Congenital Heart Surgery: its mission and history

The World Society for Pediatric and Congenital Heart Surgery (WSPCHS) was established in 2006 to assemble pediatric and congenital heart surgeons from all continents and regions of the world and their colleagues from related specialties dealing with pediatric and congenital heart disease. Since its birth, it has held a highly successful inaugural scientific meeting in 2007 in Washington, DC, and a World Summit on Pediatric and Congenital Heart Surgery Services, Education, and Cardiac Care for Children and Adults with Congenital Heart Disease in 2008 in Montreal. It currently has 549 members from 71 countries and in a short period of time has become the largest organization in the world of pediatric and congenital heart surgeons. Its brief history already seems to be a guarantee of a promising future. Projects in the areas of research, training and education, patient care, and community service will allow the Society to reach its goals. By bringing together professionals from every region of the world, the WSPCHS should play a significant role in the improvement of care for children and adults with congenital heart disease around the world.

Durability of hand-sewn valves in the right ventricular outlet

OBJECTIVE

The objective was to compare the medium- and long-term outcomes for pericardial monocusp valves, polytetrafluoroethylene (Gore-Tex, WL Gore and Associates Inc, Flagstaff, Ariz) 0.1-mm monocusp valves, and bileaflet 0.l-mm polytetrafluoroethylene valves and their efficiency in the right ventricular outlet.

METHODS

We reviewed all hand-sewn right ventricular outlet valves created by the author (Graham R. Nunn) in the setting of repaired tetralogy of Fallot or equivalent right ventricular outlet pathology when the native pulmonary valve could not be preserved. The valves were assessed by serial transthoracic echocardiography and more recently by magnetic resonance imaging angiography for late valve function. The bileaflet polytetrafluoroethylene valves were constructed in a standardized fashion from a semicircle of 0.1-mm polytetrafluoroethylene (the radius of which equaled the length of the outflow tract incision) that gave a lengthened free edge to the leaflets, central fixation of the free edge posteriorly just proximal to the branch pulmonary arteries, and generous augmentation of the outflow tract with polytetrafluoroethylene patch-plasty. The bileaflet configuration shortens the closing time against the posterior wall, and the leaflets are forced to maintain their configuration without prolapse into the right ventricular outlet. The valve can be generously oversized in young children to try to avoid the need for replacement.

RESULTS

A total of 54 patients met the selection criteria--22 patients received fresh autologous pericardial monocusps, 7 patients received polytetrafluoroethylene (0.1-mm) monocusps, and 25 patients received bileaflet polytetrafluoroethylene (0.1-mm) outlet valves. The pericardial valves have the longest follow-up, and all valves developed free pulmonary incompetence. Polytetrafluoroethylene monocusps had reliable competence early after surgery but progressed to pulmonary incompetence. The bileaflet polytetrafluoroethylene (0.1-mm) valves have remained competent with regurgitant fractions of only 5% to 30% (magnetic resonance imaging angiography), and this has remained stable with time. The maximum follow-up for these valves is 5 years. No stenosis or peripheral emboli have been recognized, and no valves have been replaced to date.

CONCLUSION

Hand-sewn bileaflet polytetrafluoroethylene valves in the right ventricular outlet can reliably provide competence and maintain function in the medium term. Their shape and size allow placement in young children with a reasonable expectation that they will remain competent with growth of the native annulus and not require replacement. Their durability is superior to the pericardial and polytetrafluoroethylene monocusp valves in this series.

Atrioventricular canal: modified single patch technique

A single surgeon experience using a modified single patch technique for the repair of 128 patients with complete atrioventricular canal is presented. Thirty-day mortality was 1.6%. Follow-up of these patients has shown no incidence of significant residual ventricular septal defect, a 2.3% incidence of reoperation on the mitral valve, and no instances of left ventricular outlet obstruction requiring resection in the follow-up period. Comparisons are drawn between these results and the author's own experience with repair of complete atrioventricular canal using a two-patch technique (46 cases) and repair of partial atrioventricular canal (126 cases) to shed light on late valve function and left ventricular outlet obstruction in all groups.

Clinical assessment of cardiac performance in infants and children following cardiac surgery

OBJECTIVE

To compare clinical assessment of cardiac performance with an invasive method of haemodynamic monitoring.

DESIGN AND SETTING

Prospective observational study in a 16-bed tertiary paediatric intensive care unit.

PATIENTS AND PARTICIPANTS

Infants and children undergoing cardiopulmonary bypass and surgical repair of congenital heart lesions.

INTERVENTIONS

Based on physical examination and routinely available haemodynamic monitoring in the paediatric intensive care unit, medical and nursing staff assessed cardiac index, systemic vascular resistance index and volume status. Clinical assessment was compared with cardiac index, systemic vascular resistance index and global end diastolic volume index, obtained by femoral artery thermodilution.

MEASUREMENTS AND RESULTS

A total of 76 clinical estimations of the three parameters were made in 16 infants and children undergoing biventricular repair of congenital heart lesions. Agreement was poor between clinical and invasive methods of determining all three studied parameters of cardiac performance. Cardiac index was significantly underestimated clinically; mean difference was 0.71 l min(-1) m(-2) (95% range of agreement +/-2.7). Clinical estimates of systemic vascular resistance (weighted kappa=0.15) and volume status (weighted kappa=0.04) showed poor levels of agreement with measured values and were overestimated clinically. There was one complication related to a femoral arterial catheter and one device failure.

CONCLUSIONS

Routine clinical assessment of parameters of cardiac performance agreed poorly with invasive determinations of these indices. Management decisions based on inaccurate clinical assessments may be detrimental to patients. Invasive haemodynamic monitoring using femoral artery thermodilution warrants cautious further evaluation as there is little agreement with clinical assessment which is presently standard accepted care in this patient population.

Mid-Term results for double inlet left ventricle and similar morphologies: timing of Damus-Kaye-Stansel

BACKGROUND

Patients with double inlet left ventricle/l-transposition and similar morphologies have their systemic outflow traverse a bulboventricular foramen (BVF), which has a propensity to narrow over time. A Norwood procedure may be performed as the initial palliation. We prefer aortic arch repair and pulmonary artery banding, delaying Damus-Kaye-Stansel (DKS) or BVF resection until the second palliation. The aims of this study were to compare our results with those reported for Norwood strategy and examine the development of systemic outflow obstruction.

METHODS

Retrospective study of patients with double inlet left ventricle, L-TGA or similar morphology presenting between 1990 and 2000. Follow-up with clinical assessment, echocardiography and catheter studies.

RESULTS

Twenty-five patients had initial palliation with pulmonary artery banding with repair of any associated arch obstruction. Twelve patients had DKS performed as part of their second stage procedure, and 3 had DKS performed later for recurrent stenosis after prior enlargement of BVF. Six patients had BVF resection without later restenosis and 4 patients did not develop BVF stenosis. There was one early death (4%) and two late (8%). Fontan completion was achieved in 20 of the 22 survivors. There were no cases of DKS obstruction, no pulmonary valve had more than mild regurgitation.

CONCLUSIONS

Our approach achieves low operative mortality and morbidity and compares favorably with reported results for Norwood palliation. The significant rate of systemic outflow obstruction in those who did not undergo DKS at the second stage confirms the utility of early DKS in children with this morphology.

Recombinant activated factor VII in paediatric cardiac surgery

OBJECTIVE

To review the use of recombinant activated factor VII in paediatric cardiac surgery.

DESIGN

Retrospective chart review.

SETTING

Paediatric intensive care unit in a stand-alone university-affiliated children's hospital.

PATIENTS AND PARTICIPANTS

Cardiac surgical patients who received recombinant activated factor VII (rFVIIa, NovoSeven; NovoNordisk, Copenhagen, Denmark) between June 2002 and June 2003 at The Children's Hospital at Westmead.

RESULTS

Six children undergoing cardiac surgery received rFVIIa. Recombinant activated factor VII was administered if bleeding was excessive and persisted despite appropriate investigation and attention to haemostasis by surgical and medical staff. An intravenous dose of 180 microg/kg was given and repeated 2 h later. All of the six patients responded well to rFVIIa with achievement of haemostasis. No adverse events were noted.

CONCLUSIONS

Recombinant activated factor VII achieved haemostasis in six paediatric cardiac surgical patients. Good outcomes and no adverse events were noted in these children.

Successful early surgical recruitment of the congenitally disconnected pulmonary artery

BACKGROUND

Our purpose was to document our experience with early recruitment of congenitally disconnected pulmonary arteries and to assess subsequent pulmonary artery growth and function.

METHODS

Patients born in the 10-year period from 1989 to 1999 with a disconnected pulmonary artery diagnosed in infancy and treated in our unit were studied. To be included patients had nonconfluent pulmonary arteries with one or both completely disconnected from the main pulmonary artery. This series did not include patients with acquired stenosis causing occlusion of a pulmonary artery. Echocardiography, cardiac catheterization, MRI, lung perfusion scans, and intraoperative assessment were used to gauge pulmonary artery growth and function.

RESULTS

Seven patients with a disconnected pulmonary artery associated with intracardiac conotruncal congenital cardiac disease underwent successful early surgical recruitment of the affected pulmonary artery at 3 months of age or younger. Median follow-up from date of first operation was 4.2 years (range, 1.6 to 13.4). All 7 patients had postrecruitment lung perfusion scans showing a mean of 44% (range, 27% to 78%) of total pulmonary flow through the affected lung. Significant growth in the diameter of the recruited native pulmonary artery was demonstrated in all patients. There were no deaths reported in our series to date.

CONCLUSIONS

The rare possibility of a congenitally disconnected pulmonary artery needs to be considered in all patients with a conotruncal cardiac anomaly. To facilitate surgical correction, ensure subsequent growth of the pulmonary artery, and optimize associated lung development, early diagnosis and surgical recruitment is recommended.

Contrast echocardiography: potential for the in-vivo study of pediatric myocardial preservation

BACKGROUND

Myocardial contrast echocardiography (MCE) has been used successfully during adult cardiac surgery to image myocardial perfusion. Recently it has been suggested this technique is capable of detecting microvascular injury and inflammation because sonicated albumin microbubbles adhere to activated neutrophils and, in the presence of denuded or inflamed endothelium, they persist within the microvasculature rather than passing unimpeded, which results in profound slowing of their transit rates. The technique has not previously been used during congenital heart surgery; however significant potential is suggested in this setting in which myocardial inflammation may contribute to postoperative myocardial dysfunction, a leading cause of morbidity and mortality. We have performed a preliminary study to assess the safety and feasibility of MCE in the pediatric intraoperative environment and to examine myocardial transit rates.

METHODS

Sonicated albumin microbubbles were injected with cardioplegia during bypass in 16 children (aged 3 weeks to 8.5 years). Images were collected using transesophageal echocardiography. Complications, post-bypass electrocardiographic, echocardiographic, and outcome data were recorded. Myocardial transit rates were calculated using videointensity analysis, assessed for reproducibility and correlated with demographic and intraoperative variables and postoperative outcome.

RESULTS

The technique was performed safely, with good reproducibility. Myocardial persistence of microbubbles, which occurred in 6 patients, was associated with crystalloid cardioplegia, prolonged preischemic bypass (r = 0.72, p = 0.004), or ischemic time (r = 0.69, p = 0.002).

CONCLUSIONS

Intraoperative MCE shows potential as an in vivo technique for the study of pediatric myocardial preservation.

Radiofrequency lesions produced by handheld temperature controlled probes for use in atrial fibrillation surgery

OBJECTIVES

Detailed analysis of the size and shape of lesions produced by handheld radiofrequency ablation devices at open heart surgery has not been reported previously.

METHODS

Radiofrequency lesions were made from the epicardial surface of the cardiac ventricles in open-chested dogs. The effects of electrode size, electrode temperature and duration of ablation were studied. In a second group of experiments simultaneous multielectrode ablation was performed on the ventricular epicardium after cold cardioplegia.

RESULTS

Using a single 12 x 2.5 mm electrode and a target temperature of 80 degrees C the lesion depth increased from 3.8+/-0.9 mm at 15 s, to 6.1+/-0.9 mm at 120 s (P=0.01). Increasing the target temperature from 70 to 90 degrees C (for 60 s) increased lesion depth from 5.0+/-1.2 to 5.6+/-1.7 mm (P=0.2). There was no difference in depth of lesions with the two electrode widths (4.0+/-0.5 mm (large) vs. 3.9+/-1.0 mm (small)). Lesions produced using the multielectrode probe (80 degrees C, 60 s) were 30-35 mm long with even penetration into the tissue. The mean depth of these lesions on microscopic sections was 3.9 mm. The mean width was 7.1 mm.

CONCLUSIONS

Handheld probes can be used to make deep linear lesions in the myocardium. Lesions expand rapidly and are wider than they are deep. A multielectrode ablation device allows rapid formation of linear lesions.

Reoperation and coarctation of the aorta: the need for lifelong surveillance

BACKGROUND

We report a series of reoperations in 23 patients who had undergone previous aortic coarctation repair.

METHODS

The medical records of these patients were reviewed, and the patients were followed up by telephone interview. Mean age at reoperation was 25 years. There was a mean of 18 years between initial coarctation repair and reoperation. Indications for reoperation included recoarctation (9 patients), aortic aneurysm (8), aortobronchial fistulas with exsanguinating hemorrhage (2), subaortic stenosis (1), ruptured thoracic aneurysm (1), ruptured sinus of Valsalva aneurysm (1), and supramitral stenosing ring (1).

RESULTS

There were no specific intraoperative complications. Three patients required reexploration for bleeding. An acutely ischemic lower limb developed in 1 patient secondary to a common femoral artery embolus, which necessitated embolectomy.

CONCLUSIONS

Reoperation for postcoarctation repair patients can be performed with good results. Sudden life-threatening hemorrhage due to aortobronchial fistulas in patients having undergone Dacron patch aortoplasty, as well as long-term obstructive phenomena seen anywhere along the left ventricular outflow tract, make lifelong surveillance of these patients mandatory.

Use of the Medtronic Freestyle valve as a right ventricular to pulmonary artery conduit

BACKGROUND

We have used the Medtronic Freestyle bioprosthesis as a right ventricular to pulmonary artery conduit recently in an attempt to overcome some of the problems associated with homografts and stented xenografts. The aim of this study was to review the performance of this prosthesis.

METHODS

Prospectively collected data for patients having Freestyle bioprostheses implanted as a right ventricular to pulmonary artery conduit were reviewed to assess clinical outcome and echocardiographic results.

RESULTS

Thirteen patients aged 13 days to 22.5 years (median, 7.9 years) underwent either primary repair (n = 5) or change of conduit (n = 8) using the Freestyle bioprosthesis. One neonate with truncus arteriosus died postoperatively of pulmonary hypertension. One conduit was explanted 27 months after repair of neonatal truncus arteriosus. There has been no incidence of significant prosthetic regurgitation, thromboembolism, or endocarditis at mean follow-up of 10.1 months (range, 2 weeks to 29 months).

CONCLUSIONS

The Medtronic Freestyle valve is a reliable pulmonary valve substitute in the short term. Early results justify continued clinical use of the device in this setting with close follow-up.

Transcaval repair of the sinus venosus syndrome

BACKGROUND

Surgical correction of the sinus venosus syndrome has been associated with sinus node dysfunction and venous obstruction postoperatively. We present the long-term follow-up of a lateral transcaval approach, which closes the atrial communication and corrects the partial anomalous pulmonary venous connection to the superior vena cava with the use of a simple pericardial patch.

METHODS

The records of 66 patients undergoing repair between April 1981 and April 1997 were examined. Mean age at repair was 10.2 years (range, 1.5-65 years; median, 5 years). Six patients had a left superior vena cava, 4 had an additional atrial septal defect, and 2 had coronary artery bypass grafts. Immediate and long-term follow-up included physical examination, electrocardiography, transthoracic echocardiography, and use of a 24-hour ambulatory Holter monitor. Sinus node function, incidence of significant arrhythmia, and evidence of mechanical venous obstruction were assessed.

RESULTS

Follow-up data were available for 64 (97%) patients for a mean follow-up of 4.1 years (range, 1-9 years). There were no deaths. No evidence of residual atrial septal defect, superior vena cava, or venous obstruction were found by echocardiography. On electrocardiography all patients were in sinus rhythm, with no arrhythmia seen. Holter monitoring was performed at a mean of 7.3 years postoperatively. All patients had normal sinus node function, and no sustained atrial arrhythmia was seen.

CONCLUSION

Transcaval repair is a simple technique that does not interfere with sinus node function. There is no evidence to suggest that this approach leads to venous obstruction.

Mechanism, localization and cure of atrial arrhythmias occurring after a new intraoperative endocardial radiofrequency ablation procedure for atrial fibrillation

OBJECTIVES

The purpose of this study was to test a new pattern of radiofrequency ablation for atrial fibrillation (AFib) intended to optimize atrial activation, and to demonstrate the usefulness of catheter techniques for mapping and ablation of postoperative atrial arrhythmias.

BACKGROUND

Linear radiofrequency lesions have been used to cure AFib, but the optimal pattern of lesions is unknown and postoperative tachyarrhythmias are common.

METHODS

A radial pattern of linear radiofrequency lesions (Star) was made using an endocardial open surgical approach in 25 patients. Postoperative arrhythmias were induced and characterized during electrophysiological studies in 15 patients.

RESULTS

The AFib was abolished in most patients (91%), but atrial flutter (AFlut) occurred in 96% of patients postoperatively. At postoperative electrophysiological studies, 37 flutter morphologies were studied in 15 patients (46% spontaneous, cycle length [CL] 223 +/- 25 ms). Seven mechanisms (lesions discontinuity, n = 6; focal mechanism, n = 1) of AFlut were characterized in six patients. In these cases, flutter was abolished using further catheter radiofrequency ablation. In the remaining cases, flutter was usually localized to an area involving the interatrial septum, but no critical isthmus was identified for ablation. After 16 +/-10 months, 15 patients (65%) were asymptomatic with (n = 3) or without (n = 12) antiarrhythmic medications. Eight (35%) patients had persistent arrhythmias. Postoperative atrial electrical activation was near physiological.

CONCLUSIONS

The AFib maybe abolished using a radial pattern of linear endocardial radiofrequency lesions, but postoperative AFlut is common even when lesions are made under optimal conditions. Endocardial mapping techniques can be used to characterize the flutter mechanisms, thus enabling subsequent successful catheter ablation.

Effect of atrial radiofrequency ablation designed to cure atrial fibrillation on atrial mechanical function

INTRODUCTION

The effects of linear radiofrequency lesions in the atria for cure of atrial fibrillation on atrial contraction have not previously been quantified.

METHODS AND RESULTS

Atrial function was measured before and 30 +/- 24 days after a biatrial ablation procedure designed to cure atrial fibrillation in eight dogs and after a sham procedure in three dogs. Atrial mechanical function was assessed using Doppler diastolic blood flow velocities, atrial systolic pressure wave amplitude, and assessment of atrial contribution to cardiac output estimated by comparison of AV sequential pacing to ventricular pacing at the same heart rate. The mitral Doppler A/E velocity ratio was 1.03 +/- 0.45 before and 0.72 +/- 0.43 after ablation (P = 0.048). The tricuspid A/E ratio was 0.88 +/- 0.17 before and 0.71 +/- 0.12 after ablation (P = 0.04). The estimated atrial contribution to cardiac output was 18% +/- 9% before and 5% +/- 4% after ablation (P < 0.01). The left atrial systolic pressure wave amplitude was 2.8 +/- 1.5 mmHg before and 1.7 +/- 1.0 mmHg after ablation (P = 0.1). These changes were not observed in control dogs. Lesions covered 25% +/- 6% of the atrial endocardial surface.

CONCLUSION

Multiple linear radiofrequency lesions in the atria designed to cure atrial fibrillation may impair atrial contractility. Reduced atrial function is partly due to loss of atrial myocardial mass, but regional delays in atrial activation and splinting of the atria by scarring also may contribute.

Simplified single patch technique for the repair of atrioventricular septal defect

OBJECTIVE

Because of the complexity of traditional 1- and 2-patch techniques for the repair of complete atrioventricular septal defect, we modified our repair technique to avoid the use of any ventricular septal patch material. We report our prospective experience with this simplified 1-patch technique.

METHOD

Forty-seven consecutive patients between May 1995 and August 1998 underwent repair with the use of this technique without modification. Repair was done in all patients by direct suturing of the common atrioventricular valve leaflets to the crest of the ventricular septum. No division of valve leaflets was necessary. A single pericardial patch was used to close the defect in the atrial septal component. Follow-up included electrocardiography and echocardiographic assessment of ventricular function, atrioventricular valve function, and adequacy of the left ventricular outflow tract.

RESULTS

There were 2 deaths (4%), only 1 cardiac related, in the series. There were 17 male patients and 30 female patients. Mean age at repair was 5.6 months (median, 3.4 months). Associated lesions were repaired in 19 patients (40%). Mean follow-up was 1.85 years (median, 1.9 years). There was no heart block. There were no significant residual ventricular septal defects detected and no left ventricular outflow tract obstruction seen on echocardiography in any patient to date. Mitral valve status after operation was assessed as no incompetence in 13 patients (28%), minimal in 19 patients (40%), mild in 12 patients (26%), and moderate in 3 patients (6%).

CONCLUSION

The repair of complete atrioventricular septal defect by direct suturing of the atrioventricular valve leaflets to the crest of the ventricular septum with a single-patch technique greatly simplifies the repair and does not lead to left ventricular outflow tract obstruction nor interfere with valve function.

Neonatal ductus arteriosus aneurysm causing nerve palsies and airway compression: surgical treatment by decompression without excision

A 4-kg male child, born at 34 weeks to a gestational diabetic mother, had a large ductus arteriosus aneurysm causing phrenic and recurrent laryngeal nerve palsies and large airway compression. The right and left atrial appendages and distal descending aorta were cannulated, allowing left heart partial or complete cardiopulmonary bypass as necessary. On bypass the ductus was ligated, decompressed, and oversewn but not excised. Examination 1 month later suggested resolution of the recurrent laryngeal palsy and echocardiography showed regression of the aneurysm. Ductus ligation and decompression was an effective surgical treatment, which is less likely to cause complications than resection.

Internal mammary artery grafting in a neonate for coronary hypoperfusion after arterial switch

Coronary hypoperfusion may occur after the arterial switch operation, especially when coronary anatomy is complicated. We report successful use of the left internal mammary artery graft for a neonate with coronary hypoperfusion after the arterial switch operation for transposition of great arteries with intramural left coronary artery. Internal mammary arteriography showed a patent graft 19 months after operation.

Ventricular assist devices in pediatric cardiac surgery

BACKGROUND

Early experience in other centers with pediatric assist devices has been favorable.

METHODS

Prospectively we examined our first 13 patients between January 1992 and September 1994.

RESULTS

Thirteen children underwent ventricular assistance at Royal Alexandra Hospital for Children. Age ranged from 4 days to 30 months, weight from 2.9 kg to 17 kg. Ventricular assistance was employed from 1.5 hours to 190 hours. Of 12 surgical patients, 8 required left ventricular assistance to be weaned from cardiopulmonary bypass after correction of congenital defects, and 4 required support in the postoperative period for refractory low cardiac output. A child was supported after a kick to the chest by a horse caused cardiogenic shock. All 13 patients initially responded to ventricular assistance and 7 remain alive. Of the deaths, 2 were neurologic, 2 due to myocardial failure, and 2 to sepsis. The major complications in the first days were hemorrhage and tamponade. Later problems included thrombosis of the circuit despite systemic heparinization, and a cannula-related tear to the anterior mitral leaflet. The 7 survivors are well after 3 to 32 months.

CONCLUSIONS

Despite the mortality and complications, we are encouraged by these results, in the light of almost certain death for all 13 patients without ventricular assistance.

Amiodarone management of junctional ectopic tachycardia after cardiac surgery in children

OBJECTIVE

To assess the effectiveness and safety of amiodarone in the treatment of junctional ectopic tachycardia (JET) after open heart surgery in children.

PATIENTS

Between January 1990 and December 1991, 16 consecutive patients aged 6 days to 14 years with JET associated with significant haemodynamic impairment after cardiopulmonary bypass were treated with amiodarone as the principal antiarrhythmic drug.

INTERVENTIONS

Amiodarone 5 mg/kg was administered intravenously over one hour and the same dose was subsequently infused over 12 hours. This was reviewed every 12 hours and repeated as necessary until a satisfactory heart rate and stable haemodynamics were achieved. Atrial pacing was used whenever possible to provide atrioventricular synchrony.

RESULTS

Except for one patient with a JET rate of 160/min, the maximum JET rate ranged from 180/min to 245/min with a mean(SD) of 200 (20)/min. After amiodarone, the heart rates reduced to a mean(SD) of 170 (20), 164 (27), 158 (27), 157 (24), and 153 (19)/min at two, four, eight, 12, and 24 hours respectively. A reduction in tachycardia rate allowing atrial pacing was achieved in 10 patients by two hours. Haemodynamic variables improved in most patients with an increase in mean systolic blood pressure by an average of 15 mm Hg and a decrease in atrial filling pressures by an average of 3.5 mm Hg at four hours after amiodarone administration. There were three deaths: one was a moribund patient who died soon after the onset of JET and the other two deaths were not directly related to JET.

COMPLICATIONS

Late bradycardia with hypotension was recorded in one patient. Asymptomatic late sinus bradycardia was seen in several others.

CONCLUSIONS

Amiodarone can be used safely and effectively to control JET with haemodynamic improvement in most patients. The addition of atrial pacing confers the advantage of atrioventricular synchrony.

High resolution mapping of Koch's triangle using sixty electrodes in humans with atrioventricular junctional (AV nodal) reentrant tachycardia

BACKGROUND

Recent evidence suggests that atrioventricular junctional reentrant tachycardia (AVJRT) uses a reentrant circuit that involves the atrioventricular (AV) node, the atrionodal connections, and perinodal atrial tissue. Electrogram morphology has been used to target the delivery of radiofrequency energy to the site of the "slow pathway," a component of this reentrant circuit. The aim of this study was to localize precisely the sites of atrionodal connections involved in AVJRT and to examine atrial electrogram morphologies and their spatial distribution over Koch's triangle.

METHODS AND RESULTS

Electrical activation of Koch's triangle and the proximal coronary sinus was examined in 13 patients using a 60-point plaque electrode and computerized mapping system. Recordings were made during sinus rhythm (n = 12), left atrial pacing (n = 8), ventricular pacing (n = 12), and AVJRT (n = 12). During sinus rhythm electrical activation approached Koch's triangle and the AV node from the direction of the anterior limbus, activating the anterior part of the triangle before the posterior part. A zone of slow conduction during sinus rhythm was found within Koch's triangle in 64% of patients. The pattern of atrial activation in Koch's triangle during anterograde fast pathway conduction was similar to that seen during anterograde slow pathway conduction. Retrograde fast pathway conduction during ventricular pacing and during anterior (typical) AVJRT caused earliest atrial activation at the apex of Koch's triangle near the AV node-His bundle junction. In individual patients the site of earliest atrial activation was similar for both anterior AVJRT and retrograde fast pathway conduction during ventricular pacing. Retrograde slow pathway conduction during ventricular pacing and during posterior (uncommon or atypical) AVJRT caused earliest atrial activation posterior to the AV node near the orifice of the coronary sinus. This posterior or "slow pathway" exit site was 15 +/- 4 mm from the His bundle. In individual patients the site of earliest atrial activation was similar for both posterior AVJRT and retrograde slow pathway conduction during ventricular pacing. In one patient anterograde and retrograde conduction occurred via separate slow pathways during AVJRT: Complex atrial electrograms with two or more components were observed near the coronary sinus orifice and in the posterior part of Koch's triangle in all cases. These were categorized as either low or high frequency potentials according to the rapidity of the second component of the electrogram. Low frequency potentials were present at the site of earliest atrial excitation during retrograde slow pathway conduction in 5 of 5 cases (100%) and high frequency potentials in 4 of 5 cases (80%). However, both slow and high frequency potentials could be found at sites up to 16 mm from the site of earliest atrial excitation.

CONCLUSIONS

At least two distinct groups of atrionodal connections exist. The site of earliest atrial activation during anterior AVJRT is similar to that of fast pathway conduction during ventricular pacing. This site is close to the His bundle-AV node junction. The site of earliest atrial activation during posterior AVJRT is similar to that of slow pathway conduction during ventricular pacing. This site is near the coronary sinus orifice, approximately 15 mm from the His bundle. The anterograde slow pathway appears to be different from the retrograde slow pathway in some patients. Double atrial electrograms are an imprecise guide to the site of earliest atrial excitation during retrograde slow pathway conduction.

Incessant ventricular tachycardia in infancy

Two infants with incessant tachycardia uncontrolled by multiple drug treatment were thought initially to have supraventricular tachycardia. Careful examination of the 12-lead electrocardiogram suggested ventricular tachycardia, which was confirmed by electrophysiological studies. Intra-operative mapping showed that the arrhythmia arose from the posterior left ventricular free wall in one infant and at the left ventricular apex in the other. Cryoablation of these foci led to cessation of ventricular tachycardia. Myocardial biopsy showed hamartomatous involvement in the first infant and normal tissue in the other. In the first infant the incessant arrhythmia was cured but in the other it recurred 4 months later. The origin of the recurrent tachycardia was adjacent to the previously cryoablated arrhythmogenic area. This area was also cryoablated, leading to disappearance of the ventricular tachycardia. Both patients are free of arrhythmia 10 months and 3 months after their surgery. Surgically ablatable lesions are common in infants with incessant ventricular tachycardia. Early diagnosis and prompt surgical treatment usually can effect 'cure' of this potentially fatal problem in childhood.

Use of desmopressin in the management of aspirin-related and intractable haemorrhage after cardiopulmonary bypass

Desmopressin (DDAVP) has been used both prophylactically and therapeutically in the management of excessive bleeding after cardiopulmonary bypass. A series of four consecutive cases is presented in which DDAVP was used to treat excessive bleeding, associated with aspirin antiplatelet therapy in three cases and after all other measures had failed in one. The therapeutic use of DDAVP in aspirin-related bleeding after bypass has not been reported previously. There was no measured haemodynamic effect of the regimen used. Bleeding ceased promptly after administration of DDAVP in all cases. No morbidity was observed in any of the patients. The indications for use of DDAVP and postulated mechanisms of action are discussed.

Surgical therapy for atrial tachycardia in adults

Eighteen adult patients with atrial tachycardia refractory to treatment with a mean of four drugs underwent attempted surgical cure. Atrial tachycardia originated in the right atrium in 17 patients and the left atrium in 1 patient. Tachycardia could be reproducibly induced and terminated by atrial extrastimuli or atrial pacing in 8 patients (44%). Resection of the arrhythmogenic area was performed in 16 patients (89%), and an isolation procedure was performed in 1 patient. In seven cases (39%), the area of isolation or excision included the sinoatrial node. One patient underwent His bundle section because the arrhythmogenic region was too close to the atrioventricular (AV) conduction system to enable resection. The mean duration of clinical follow-up was 56 +/- 34 months. Clinical tachycardia recurred in five patients (28%), but in two patients it did not recur until greater than 1 year after surgery. A permanent pacemaker was implanted in 3 (18%) of the 17 patients whose His-Purkinje system was left intact. One other patient had required permanent pacing before surgery. Only one of the seven patients undergoing sinoatrial node resection or isolation required permanent pacing for symptomatic bradycardia. Apart from the requirement for permanent pacing, no significant complications occurred. Surgical therapy for atrial tachycardia is a safe procedure, but the rate of cure appears to be less than that of supraventricular tachycardias associated with accessory AV connections. Excision or isolation of the sinoatrial node does not necessitate permanent pacing in most patients.

Report of four cases of aneurysm complicating patch aortoplasty for repair of coarctation of the aorta

Patch aortoplastry, used almost routinely in the period 1972-86, except in infants in the operative treatment of coarctation of aorta, is sometimes complicated by late formation of true or false aneurysms. This complication, which seems likely to increase with longer follow-up, calls into question the advisability of patch aortoplasty except when it has specific advantages. Other surgical techniques such as subclavian flap angioplasty in infants and young children or radical excision with end-to-end anastomosis may be preferable where there is no anatomical contraindication. In any case, lifelong yearly review of postoperative patients should include chest X-ray and further investigation by computerized tomography scanning or other suitable imaging of those with suspicious findings.

Nitroprusside in children after cardiopulmonary bypass: a study of thiocyanate toxicity

Thiocyanate levels, an indicator of nitroprusside toxicity, were studied in 22 children after repair of structural heart disease during cardiopulmonary bypass. At the total dose (2.6 +/- 2.3 mg/kg) and time (34.4 +/- 19 h) ranges of this study, no evidence of toxicity was detected, despite this total dose exceeding recommended maximum in some patients. Nitroprusside infusion, as described, in children with normal hepatic and renal function is safe and may not warrant routine assessment of thiocyanate levels.

Surgery for supraventricular tachycardia (SVT)

All forms of supraventricular tachycardia (SVT) are now potentially curable by surgery and we believe that patients should be offered surgery as an initial therapeutic option. At Westmead Hospital, 311 patients have undergone surgery for SVT, 13 having AV node ablation, a procedure now rarely performed, and 298 have had attempts at curative surgery. One hundred and ninety-nine patients were diagnosed primarily as having a Wolff-Parkinson-White syndrome (WPW) and 139 had free wall or anterior septal connections with a clinical cure rate of 98.0%. The failures were entirely due to unrecognised posterior septal connections. Sixty patients had primarily posterior septal connections with a clinical cure rate of 96%. Atrioventricular junctional re-entry tachycardia may now be cured, probably by dividing an extra nodal His-to-atrial connection. Seventy-eight patients have undergone surgery with a clinical cure rate of 92%. Fifteen patients with right atrial tachycardias, 4 patients with nodo-ventricular fibres and 2 with incessant AV tachycardia have undergone surgery. The overall clinical cure rate for all patients is 95% and 92% at late electro-physiological study (EPS).

Management of ascending aortic dissection: experience with the USCI intraluminal prosthesis and a method of aortic valve repair

Ten consecutive cases of acute ascending aortic dissection operated on using the USCI intraluminal prosthesis from 1983 to 1986 were reviewed. Diagnosis was achieved by conventional angiography in six cases, by intraarterial digital subtraction angiography in one case, by computerized tomography (CT) scan in two cases and by echocardiography and abdominal ultrasound in one case. An entry site was seen in only five out of six conventional angiograms. At operation six of the 10 had a degree of tamponade. Aortic regurgitation was seen five times, due to dissection in four cases and to Marfan's disease in one. The entry site was controlled in eight cases. Repair using intraluminal prosthesis only was achieved in five cases. Aortic valve repair was added in four out of 10 cases, and in one of these an aorta-to-right coronary graft was also added. One case required aortic valve replacement. A method of aortic valve repair is presented. There were nine survivors, 1-36 months postoperatively. Of these, eight were asymptomatic on no medication. One had severe aortic regurgitation noted 2 months postoperatively and has mildly reduced exercise tolerance. Surgical treatment can be planned if the presence of dissection is proven and involvement of the ascending aorta is demonstrated. Early surgery is important, since six of the 10 cases in this series had tamponade. The intraluminal graft will reliably redirect flow to the true lumen and exclude the dissection from the pericardium. Aortic valve repair can be successful though late replacement may be necessary in some cases. Control of the entry site is not essential to achieve a good clinical result.

Aorta-coronary bypass grafting with polytetrafluoroethylene conduits. Early and late outcome in eight patients

During 1982 and 1983 we performed aorta-coronary bypass grafts on eight patients using 4 mm polytetrafluoroethylene conduits and predominantly the multiple sequential graft technique. Angiography was performed 1 week postoperatively and seven of eight patients had patent grafts and were angina free. At 1 year's follow-up 18 of 28 distal anastomoses were patent and five of eight patients were angina free. At 45 month's follow-up four of 28 distal anastomoses were patent and one of eight patients was angina free.

Surgical therapy for supraventricular tachycardia, a potentially curable disorder

One hundred fifty-six patients underwent investigation and operation for supraventricular tachycardia: 145 had attempts at curative operations and 11 had His bundle section. Operative mortality was 0.68% and there were no late deaths among patients having curative operations. One patient died suddenly 1 year after His bundle section. All patients underwent electrophysiologic study before discharge and 6 months postoperatively. A satisfactory result, without supraventricular tachycardia and without medication, was achieved in 96.5% of all patients. Ninety-three percent have no supraventricular tachycardia and no demonstrable reentrant pathway at electrophysiologic study. All free wall accessory atrioventricular connections were divided and 97.7% of the patients were cured. Ninety percent of patients with posterior septal accessory atrioventricular connections had a satisfactory result, with cure demonstrated at late electrophysiologic study in 84%. Fifteen patients with atrioventricular junctional reentrant tachycardia were all cured, with preservation of normal atrioventricular conduction. Eight (88%) of nine patients with right atrial tachycardia were cured, and two patients with nodoventricular fibers and one patient with incessant atrioventricular junctional tachycardia had satisfactory results. Supraventricular tachycardia is now a potentially curable disorder when managed by low risk surgical procedures that offer a high cure rate.

Primary left ventricular rhabdomyosarcoma in a child: noninvasive assessment and successful resection of a rare tumor

Rhabdomyosarcoma of the heart is a rare tumor, especially in childhood and particularly in the left ventricle. A primary tumor of this type was successfully resected after echocardiographic assessment alone in a young girl exposed prenatally to diphenylhydantoin. The patient is well and free of recurrence 2 1/2 years later.

Arteriovenous fistula following lumbar disc surgery--the use of total cardiopulmonary bypass during repair

Arteriovenous fistula is a rare complication of lumbar disc surgery and there is often a delay in diagnosis. A patient who developed multi-system failure associated with an aortocaval fistula, which occurred following a lumbar disc operation, is presented in this study. Surgical repair was facilitated by the use of total cardiopulmonary bypass which enabled a degree of safety and control that would have been difficult to obtain with standard methods.

Pulmonary sequestration in a newborn mimicking cardiac disease: a trap for diagnosis

A case of pulmonary sequestration in a neonate presenting with hyperdynamic circulation and a murmur is reported. Clinical, radiographic and echocardiographic data suggested the diagnosis and this was confirmed by angiography. The surgical findings were those of sequestration of the right lower lobe, in conjunction with an accessory right lung complete with bronchial and vascular supply arising from the region of the lower oesophagus. Pulmonary sequestration may mimic primary cardiovascular disease in the neonate.

Effect of fluocarbon exchange transfusion on myocardial infarction size in dogs

Fluosol DA (20%), a perfluocarbon with high oxygen solubility, was administered by concurrent exchange transfusion (30 ml/kg) to anesthetized open-chested adult greyhounds (n = 9) 1 hour after left anterior descending coronary ligation. Mechanical ventilation using 100% oxygen was used throughout the experiment. A second similar group (n = 9) received 0.9% normal saline solution (30 ml/kg), and a third group (n = 9) received no further intervention. Systemic, right atrial, and left atrial pressures were not altered by the exchange transfusion. Monastryl blue dye was injected through the left atrial line at 6 hours after ligation to define the area of myocardium at risk (AR); the animals were then killed and the heart was excised. The left ventricle was sliced at 5 mm intervals and stained using triphenyltetrazolium chloride, defining areas of necrosis (AN). The ratio of AN/AR and total left ventricular mass were then compared with the use of planimetry. The results were as follows: the AN/AR ratio in the 9 control animals was 90 +/- 2 (mean +/- standard error of the mean); in the 9 animals who received saline solution it was 88 +/- 2; and in the animals who received Fluosol it was 67 +/- 4 (p less than 0.01 compared with control; p less than 0.001 compared with the saline group). Fluocarbon exchange transfusion may reduce infarct size when administered after coronary occlusion.

Coronary artery surgery in South Australia: second report

This is the second report on the results of coronary artery grafting in South Australia. Symptomatic relief after grafting has continued at a high level (at five years, the conditions of 90.3% of surviving patients are improved as assessed by their cardiologists), and, in patients with significant symptoms, the operation can be recommended with a high degree of safety on these grounds alone. In addition, an attempt has been made to ascertain whether grafting alters longevity and, although more information is required on this point, the initial results are most encouraging with the five-year survival rate for operated patients being 92%, a figure which compares favourably with any large, medically treated group of patients. The operative mortality rate has continued to fall and is 2.2% for the entire series.

Coronary artery surgery in South Australia 1970-1976

The South Australian population of approximately 1,245,000 is 9.2% of the total Australian population. The Cardio-Thoracic Surgical Unit of the Royal Adelaide Hospital is the only one such unit in the State which is equipped for open heart surgery, and coronary artery grafting was first undertaken there in December, 1970. From that time until the end of December, 1976, 701 patients underwent coronary artery grafting with an overall hospital mortality of 3.0%, and a late mortality of 3.2%. The principal indication for operation was incapacitating angina, and of the 628 patients who have been followed-up after operation for a minimum period of six months, 78.6% were judged by their cardiologist to be completely relieved of this symptom. A further 8.9% of patients were considered to be significantly improved. Coronary artery surgery has rapidly assumed a dominant role in our Unit so that, in 1976, of the 435 open heart operations which were performed, 267 (61%) were procedures which necessitated coronary artery grafting. The rate of increase has slowed considerably over the past 18 months, and it is expected that, with current operative indications, the proportion of coronary artery cases will not rise much above 60% of the open heart work load of the Unit.

Cardiac surgery relative to population: pattern of cardiac surgery in South Australia, 1949--75

The total work load of the sole cardiac surgery unit in South Australia has been analysed by means of a computer-based data retrieval system. The review covers the period 1949--75 inclusive. This study analyses the case-loads year by year, in total, and in different diagnostic categories, and has allowed conclusions to be drawn about surgical needs relative to population figures. From these figures future trends in requirements for cardiac surgical facilities have been deduced. There are many lessons to be learnt by maintaining an easily recoverable set of data for all the surgery performed in any cardiac surgery unit. This type of analysis makes it possible to maintain surveillance of demands on resources and of the results of the surgery performed. Because of the structure and situation of the community of South Australia and the fact that it is served by a single open heart unit, the pattern of this series may truly represent the optimum cardiac surgery case-load for any modern westernised community of comparable size.