Evolution in the management of aorta to left ventricular tunnel in a national congenital cardiology centre

An aorto-ventricular tunnel is a rare congenital cardiac defect, where a channel connects the lumen of the ascending aorta to the left or right ventricle. Four patients presented with an aorto-left ventricular tunnel over two decades at a median age of 8 months (range 0.1-10 months). Two patients (50%) had associated cardiac anomalies including hypoplastic left heart syndrome and left ventricular noncompaction/hypertrophic cardiomyopathy with aortic/pulmonary valve dysplasia in one patient each. Although traditionally surgical treatment has addressed this problem, management has evolved to transcatheter closure with excellent outcomes in appropriately selected patients at our national centre.

Leadless Micra Pacemaker Use in the Pediatric Population: Device Implantation and Short-Term Outcomes

The development of Leadless cardiac pacemakers avoids the inherent complications that may occur secondary to lead insertion. A large number of devices have been inserted in adult patients although data in pediatric patients are lacking. We aimed to assess our experience with the Leadless device in the pediatric population. We performed a retrospective study on all pediatric patients who underwent insertion of a Leadless pacemaker in our center. Data were collected for demographic, procedural, and outcome variables. Nine patients with a median (IQR) age and weight of 13 (12-14) years and 37 (31-50) kg, respectively, were enrolled. The median (IQR) procedural time was 62 (60-65) min with insertion thresholds of 0.5 (0.35-1) Volts at 0.24 ms. All devices were successfully inserted without complication. One device was replaced with a single-lead endocardial pacemaker at 1 year for increased thresholds. Leadless pacemaker device insertion is feasible in pediatric patients. Further studies and long-term follow-up are needed to ascertain device longevity and complication rates.

Transcatheter Mitral Valve-in-Ring Implantation

Failed surgical mitral valve repair using an annuloplasty ring has traditionally been treated with surgical valve replacement or repair1. For patients at high risk for repeat open heart surgery, placement of a trans-catheter aortic valve (i.e., TAVI valve) within the mitral ring (i.e., Mitral-Valve-in-Ring, MViR) has emerged as a novel alternative treatment strategy2-5 . We describe our experience of a failed mitral valve repair that was successfully treated with a TAVI valve delivered via the trans-septal approach, and summarise the data relating to this emerging treatment strategy.

Coronary stent insertion into a 20-year-old Blalock-Taussig Shunt

A 21 year-old female with complex congenital heart disease presented with declining exercise tolerance, presyncope and increasing cyanosis despite regular venesection. Her double inlet left ventricle with rudimentary right ventricle, restrictive ventricular septal defect and pulmonary stenosis had been managed with a Classic Left Blalock-Taussig (B-T) Shunt aged 2 months and a Modified Right B-T Shunt at 4 years. Aortography revealed a patent but significantly narrowed Left B-T shunt with impaired blood flow and an aneurysmal pulmonary artery. Angioplasty and stenting of the shunt was undertaken and a 4.0 x 12mm coronary stent deployed. The patient's arterial oxygen saturation improved from 76% on pulse oximetry to 85% post procedure and she reported significantly improved exercise tolerance upon follow-up.

Atrioventricular block after transcatheter closure of perimembranous ventricular septal defects

OBJECTIVE

To look at the presentation, treatment and outcome of patients who developed atrioventricular block after transcatheter closure of a perimembranous ventricular septal defect (PMVSD) with the Amplatzer PMVSD device.

SETTING

Three tertiary referral centres for paediatric cardiology in two countries.

RESULTS

All three patients presented within 10 days of the procedure. All three patients were treated with intravenous steroids. A permanent pacemaker was inserted in all patients but no pacemaker required activation after two months.

CONCLUSION

Complete atrioventricular block occurring in the weeks after device occlusion of a PMVSD appears to resolve quickly. Continued involvement in multicentre device databases is required to monitor safety.

Clopidogrel reduces migraine with aura after transcatheter closure of persistent foramen ovale and atrial septal defects

OBJECTIVE

To report the clinical events leading to alteration of an anticoagulation regimen for patients undergoing transcatheter closure of an atrial shunt and how this affected migraine symptoms after the closure procedure.

METHOD

Audit of a change of anticoagulant regimen.

RESULTS

In the first few weeks after a closure procedure migraine frequency and severity increased despite treatment with aspirin for six months in 71 patients. Severe attacks of migraine with aura, including status migrainosus, in the first few weeks after transcatheter closure were terminated by addition of clopidogrel to aspirin treatment. Therefore, the anticoagulant regimen was changed with addition of clopidogrel for the first month after the closure procedure (90 procedures in 89 patients). Fewer patients had migraine with aura in the first month after transcatheter closure when taking the combination of clopidogrel and aspirin compared with aspirin alone (11 of 90 (12.2%) v 30 of 71 (42.3%), p < 0.001). Episodes of migraine with aura were more severe and more frequent in patients taking aspirin alone.

CONCLUSION

The combination of clopidogrel for four weeks and aspirin for six months is superior to aspirin alone for six months for preventing migraine with aura after transcatheter closure of an atrial shunt. This beneficial effect of a powerful inhibitor of platelet aggregation suggests that platelets may have a role in pathogenesis of migraine. This may be because of an effect on serotonin stores. Whether clopidogrel has a role in treatment of migraine in other clinical situations requires investigation.

Advanced embolization techniques

The techniques of transcatheter embolization of unwanted blood vessels in patients with congenital heart disease have evolved considerably during the past 25 years. There are many different anatomical lesions requiring different approaches and devices. The main types of devices used can be classified into particles, coils, and plugs. It is important for the operator to be familiar with a range of these devices. The results of transcatheter embolization are usually excellent, and technical problems and complications can usually be overcome by attention to detail and persistence. The types of devices in common use and their clinical applications are discussed.

Inheritance of persistent foramen ovale and atrial septal defects and the relation to familial migraine with aura

OBJECTIVE

To determine whether smaller atrial shunts (large persistent foramen ovale (PFO) and small atrial septal defect (ASD)) are inherited and whether this has a role in the inheritance of migraine with aura.

METHODS

Contrast echocardiography was used to detect atrial shunts in 71 relatives of 20 probands with a significantly sized atrial shunt (large PFO or ASD). Four families with three generations, 14 families with two generations, and two sibships were studied. The contrast echocardiograms were performed blind to history of migraine. A consultant neurologist, who was blinded to cardiac findings, categorised migraine symptoms in subjects.

RESULTS

The occurrence of atrial shunts was consistent with autosomal dominant inheritance. Usually shunts were large PFOs, but in some cases they were ASDs. There was also evidence that inheritance of more complex congenital heart disease may be related to the inheritance of PFOs. When the proband had migraine with aura and an atrial shunt, 15 of the 21(71.4%) first degree relatives with a significant right to left shunt also had migraine with aura compared with three of 14 (21.4%) without a significant shunt (p < 0.02).

CONCLUSIONS

There is dominant inheritance of atrial shunts. This is linked to inheritance of migraine with aura in some families.

Relationship between right-to-left shunts and cutaneous decompression illness

The presence of a large right-to-left shunt is associated with neurological decompression illness after non-provocative dives, as a result of paradoxical gas embolism. A small number of observations suggest that cutaneous decompression illness is also associated with a right-to-left shunt, although an embolic aetiology of a diffuse rash is more difficult to explain. We performed a retrospective case--control comparison of the prevalence and sizes of right-to-left shunts determined by contrast echocardiography performed blind to history in 60 divers and one caisson worker with a history of cutaneous decompression illness, and 123 historical control divers. We found that 47 (77.0%) of the 61 cases with cutaneous decompression illness had a shunt, compared with 34 (27.6%) of 123 control divers (P<0.001). The size of the shunts in the divers with cutaneous decompression illness was significantly greater than in the controls. Thus 30 (49.2%) of the 61 cases with cutaneous decompression illness had a large shunt at rest, compared with six (4.9%) of the 123 controls (P<0.001). During closure procedures in 17 divers who had cutaneous decompression illness, the mean diameter of the foramen ovale was 10.9 mm. Cutaneous decompression illness occurred after dives that were provocative or deep in subjects without shunts, but after shallower and non-provocative dives in those with shunts. The latter individuals are at increased risk of neurological decompression illness. We conclude that cutaneous decompression illness has two pathophysiological mechanisms. It is usually associated with a large right-to-left shunt, when the mechanism is likely to be paradoxical gas embolism with peripheral amplification when bubble emboli invade tissues supersaturated with nitrogen. Cutaneous decompression illness can also occur in individuals without a shunt. In these subjects, the mechanism might be bubble emboli passing through an 'overloaded' lung filter or autochthonous bubble formation.

Mechanical occlusion of the patent ductus arteriosus with Jackson coils

The effectiveness and safety of a protocol for transcatheter patent ductus arteriosus (PDA) closure was assessed. Our goal is complete mechanical occlusion of the PDA in the catheterization laboratory by adding coils until it is no longer possible to cross the PDA with a guidewire. Detachable coil closure of a PDA with a narrowest diameter of 2.4 +/- 0.1 mm was attempted in 83 patients with a median age of 2.8 years (0.7 to 27.8 years) and whose median weight was 14.5 kg (6 to 61.6 kg). Coils were successfully implanted in 82 of 83 patients, and in 1 patient a large Rashkind double umbrella was used instead. Complete closure was obtained in 80 (97.6%) patients, 48 of those (59%) received more than one coil. Reintervention for residual shunting was required in only 1 patient and another patient has a trivial residual shunt. Device embolization occurred in three cases. Despite the use of multiple coils there was no evidence of significant left pulmonary artery stenosis. The fluoroscopy time increased from 14.0 +/- 2.0 minutes for a single coil to 25.3 +/- 2.9 minutes for multiple coils (p < 0.01). Attempting to obtain complete mechanical occlusion of the PDA during the implant procedure by adding extra coils reduces the need for reintervention for residual or recurrent shunting.

Effect on migraine of closure of cardiac right-to-left shunts to prevent recurrence of decompression illness or stroke or for haemodynamic reasons

BACKGROUND

A relation between migraine with aura and cardiac right-to-left shunts has been reported. Right-to-left shunts are also associated with stroke and certain forms of decompression illness. We investigated the effect of closure of right-to-left shunts on migraine symptoms.

METHODS

A consultant neurologist, who was unaware of information about residual shunt, undertook a structured interview with individuals who had had transcatheter closure of an atrial septal defect or patent foramen ovale to assess how the procedure affected migraine symptoms.

FINDINGS

37 of 40 consecutive patients who had had a closure procedure (to permit resumption of diving after decompression illness in 29, after stroke when paradoxical thromboembolism was suspected in four, or to close a large atrial septal defect in four) could be contacted. 21 (57%) had a history of migraine before the procedure (with aura in 16, without aura in five). 11 individuals had fortification spectra in the period immediately after closure. During long-term follow-up, no migraine symptoms were reported by seven individuals who had previously had migraine with aura and three who had previously had migraine without aura. Eight others who had had migraine with aura before closure reported improvement in frequency and severity of migraines. Three (one migraine with aura, two migraine without aura) reported no alteration in migraine episodes.

INTERPRETATION

These observations suggest a causal association between right-to-left shunts and migraine with aura. There may be a subgroup of patients who have severe migraine associated with a large right-to-left shunt in whom closure of the atrial defect may improve or abolish migraine.

The Amplatzer septal occluder

The Amplatzer Septal Occluder is made from a Nitinol wire mesh shaped into 2 disks with a connecting waist, which serves to center the device in the defect while occluding it. The Amplatzer device is also available in a configuration with no central waist for use in patients with patent oval foramen, or multi-perforated aneurysm of the interatrial septum. For the purposes of this review, we analysed our experience using the Amplatzer device in 150 patients with interatrial communications. Of these, 104 had a defect within the oval fossa, 33 a patent oval foramen, and 13 had undergone fenestration of a Fontan procedure. Of those with defects within the oval fossa, a device was implanted in 100 patients, and 2 of these patients subsequently required surgical intervention, 1 because of migration and the other because of malformation of the device. Of the remaining 98 patients, complete occlusion has been achieved in 90% at 1 year. Any residual leaks are either trivial or small. In those with a patent oval foramen, the septal occluder was used to close 20, whilst the device designed specifically for this purpose was used in 13. On follow-up contrast echocardiography, only 2 patients have a small residual right-to-left shunt. Complete occlusion was achieved for all the Fontan fenestrations, although 1 patient later underwent surgery for baffle dehiscence. Other significant complications occurred in 2 patients who developed deep vein thrombosis, and 3 patients who suffered transient supraventicular arrhythmias. Although the Amplatzer device has been in clinical use for only 3 years, its unique design, and ease of use, has resulted in its widespread adoption by many centres. The results to date are very encouraging, but it must be remembered that there is, as yet, no long-term follow-up data available for this life-long implant.

Results of transvenous occlusion of secundum atrial septal defects with the fourth generation buttoned device: comparison with first, second and third generation devices. International Buttoned Device Trial Group

OBJECTIVES

The purpose of this study was to assess safety and effectiveness of the fourth generation buttoned device in dosing atrial septal defects (ASDs) and to test the hypothesis that introduction of double button reduces unbuttoning rate without reducing effectiveness.

BACKGROUND

Because of the high unbuttoning rate (7.2%) with first, second and third generation buttoned devices, the device was modified (fourth generation) so that there were two radiopaque spring buttons 4 mm apart on the button loop attached to the occluder.

METHODS

During a four-year period ending in September 1997, 423 patients, ages 1.5 to 80 years (median 16 years), underwent closure of ASD at 40 medical centers around the world.

RESULTS

The ASD size varied between 5 and 30 mm (median 17 mm). The device size varied between 25 and 60 mm. Unbuttoning occurred in 4 (0.9%) of 423 patients. Effective occlusion, defined as no (n = 343) or trivial (n = 34) residual shunt on echo-Doppler studies performed within 24 h of the procedure, was demonstrated in 377 patients (90%). Thus, the unbuttoning rate (0.9 vs. 7.2%) decreased (p<0.01) while effective occlusion rate (90 vs. 92%) remained unchanged (p>0.1) with this device, compared with earlier generation devices. During follow-up from one month to five years (23+/-15 months), 21 (5%) of 417 patients required surgical (n = 12) or transcatheter (n = 9) reintervention, mostly to treat significant residual shunt. In the remaining patients there was gradual reduction and disappearance of the residual shunt. No wire integrity problems were observed.

CONCLUSIONS

These data suggest that the fourth generation buttoned device is as effective as earlier generation devices, but without significant unbuttoning. Follow-up results remained good, with a reintervention-free rate of 89% at five years.

Doppler ultrasonography and single-fiber laser Doppler flowmetry for measurement of hind limb blood flow in anesthetized horses

OBJECTIVE

To use Doppler ultrasonography and single-fiber laser Doppler flowmetry (LDF) to evaluate blood flow in the dependent and nondependent hind limbs of anesthetized horses and to evaluate changes in femoral arterial blood flow and microvascular skeletal muscle perfusion in response to administration of phenylephrine hydrochloride or dobutamine hydrochloride.

ANIMALS

6 healthy adult horses.

PROCEDURE

Horses were anesthetized and positioned in left lateral recumbency. Doppler ultrasonography was used to measure velocity and volumetric flow in the femoral vessels. Single-fiber LDF was used to measure relative microvascular perfusion at a single site in the semimembranosus muscles. Phenylephrine or dobutamine was then administered to decrease or increase femoral arterial blood flow, and changes in blood flow and microvascular perfusion were recorded.

RESULTS

Administration of phenylephrine resulted in significant decreases in femoral arterial and venous blood flows and cardiac output and significant increases in mean aortic blood pressure, systemic vascular resistance, and PCV. Administration of dobutamine resulted in significant increases in femoral arterial blood flow, mean aortic blood pressure, and PCV. Significant changes in microvascular perfusion were not detected.

CONCLUSION AND CLINICAL RELEVANCE

Results suggest that Doppler ultrasonography and single-fiber LDF can be used to study blood flows in the hind limbs of anesthetized horses. However, further studies are required to determine why changes in femoral arterial blood flows were not associated with changes in microvascular perfusion.

Dermatomyositis and Whipple's disease

A 14-year-old boy presented with a 3-year history of a skin rash typical of juvenile dermatomyositis, and a 2-month history of mild proximal weakness, myalgia, and weight loss. A quadriceps biopsy showed perifascicular fibre atrophy, focal necrosis and regeneration, immunohistochemical labelling for HLA-1 on the surface of the fibres, and focal C5-9 deposition in capillaries. Macrophages with diastase-resistant, PAS-positive cytoplasm were present. Ultrastructural studies showed electron dense and membranous debris. The patient's symptoms responded to intravenous immunoglobulin and oral prednisolone. Four months after discontinuing prednisolone, the patient developed cardiac failure, ventricular tachycardia, and a recurrence of his rash. The 16S ribosomal RNA specific for Tropheryma whippelii was identified by polymerase chain reaction (PCR) analysis in skeletal and cardiac muscle. The myalgia and skin rash responded to prednisolone and oral co-trimoxazole, and the tachycardia is controlled by oral verapamil. This patient appears to have a novel association of juvenile dermatomyositis and Whipple's disease.

Lung perfusion studies after detachable coil occlusion of persistent arterial duct

OBJECTIVE

To evaluate relative lung perfusion following complete occlusion of persistent arterial duct with detachable Cook coils.

METHODS

Ductal occlusion using detachable coils was performed in 35 patients (median age 3.9 years, range 0.5 to 16; 32 native ducts, three patients with previous devices). If the duct could be crossed with a 0.035 inch guidewire and a 4 F catheter after coil implantation, a further coil was implanted. Between one and seven coils were used (median two).

RESULTS

Complete ductal occlusion was confirmed by echocardiography 24 hours after the procedure in all patients. Lung perfusion scans were performed three months after the procedure in 33 of 35 patients (two older patients with a single coil each did not attend). Decreased perfusion to the left lung (defined as < 40% of total lung flow) was observed in only one patient, who had previously had a 17 mm Rashkind umbrella implanted. There was no correlation between left lung perfusion and peak left pulmonary artery Doppler velocities (r = 0.27 and p = 0.125 for the entire group; r = 0.29 and p = 0.124 after excluding patients with previous devices).

CONCLUSIONS

Coil occlusion is effective in achieving complete closure of the duct. An aggressive approach using multiple coils did not compromise perfusion to the left lung.

Transcatheter closure of a mid-muscular ventricular septal defect with an amplatzer VSD occluder device

A 5 year old girl with a haemodynamically significant mid-muscular ventricular septal defect (VSD) had successful transcatheter closure using the Amplatzer VSD occluder. This device passes through a small diameter sheath and can be easily retrieved or repositioned. These properties may make it a suitable device for closure of large mid-muscular defects in small children.

Comparison of the Sideris and Amplatzer septal occlusion devices

The results of transcatheter atrial septal defect (ASD) occlusion with 2 different devices (Sideris adjustable buttoned device vs Amplatzer Septal Occluder) were compared in 2 consecutive series of patients. Comparative outcomes were assessed by whether a device was implanted or not, by complications and fluoroscopy time of implantation, and by the incidence of residual shunting on transthoracic echocardiography at follow-up. The patient and defect characteristics were similar in both groups. Twenty-eight of 33 Sideris devices and 37 of 39 Amplatzer devices were implanted. The fluoroscopy time for the Amplatzer implants was 13.4 minutes (range 8 to 41) compared with 23.7 minutes (range 11 to 60.6) for the Sideris implants (p <0.001). The complete occlusion rate for the Amplatzer device was 93% compared with 44% for the Sideris device at 1 year (p <0.001). In conclusion, the Amplatzer device produces higher occlusion rates of ASDs with shorter fluoroscopy times.

Transcatheter closure of patent foramen ovale using the Amplatzer septal occluder to prevent recurrence of neurological decompression illness in divers

OBJECTIVE

Large flap valve patent foramens may cause paradoxical thromboembolism and neurological decompression illness in divers. The ability of a self expanding Nitinol wire mesh device (Amplatzer septal occluder) to produce complete closure of the patent foramen ovale was assessed.

PATIENTS

Seven adults, aged 18-60 years, who had experienced neurological decompression illness related to diving. Six appeared to have a normal atrial septum on transthoracic echocardiography, while one was found to have an aneurysm of the interatrial septum.

METHODS

Right atrial angiography was performed to delineate the morphology of the right to left shunt. The defects were sized bidirectionally with a precalibrated balloon filled with dilute contrast. The largest balloon diameter that could be repeatedly passed across the septum was used to select the occlusion device diameter. Devices were introduced through 7 F long sheaths. All patients underwent transthoracic contrast echocardiography one month after the implant.

RESULTS

Device placement was successful in all patients. Device sizes ranged from 9-14 mm. The patient with an aneurysm of the interatrial septum had three defects, which were closed with two devices. Right atrial angiography showed complete immediate closure in all patients. Median (range) fluoroscopy time was 13.7 (6-35) minutes. Follow up contrast echocardiography showed no right to left shunting in six of seven patients and the passage of a few bubbles in one patient. All patients have been allowed to return to diving.

CONCLUSION

The Amplatzer septal occluder can close the large flap valve patent foramen ovale in divers who have experienced neurological decompression illness. Interatrial septal aneurysms with multiple defects may require more than one device.

Transcatheter closure of a residual postmyocardial infarction ventricular septal defect with the Amplatzer septal occluder

Acute ventricular septal rupture following myocardial infarction carries a high mortality. Early surgery improves survival but long term outcome depends on residual shunting and left ventricular function. Residual shunting is common despite apparently successful closure and may require reoperation. Transcatheter closure is an established method of treating selected congenital defects but clinical experience of transcatheter closure in postinfarction ventricular septal rupture is minimal. Transcatheter closure of a residual ventricular septal defect was successfully done using a new device, the Amplatzer septal occluder, in a 50 year old Indian man who had previously undergone emergency surgical repair for postinfarction acute ventricular septal rupture. The technique is described and its potential as a treatment in postinfarction ventricular septal rupture, its possible complications, and the important aspects of case selection and device design are discussed.

Transcatheter occlusion of a post-Fontan residual hepatic vein to pulmonary venous atrium communication using the Amplatzer septal occluder

A residual hepatic vein to left atrial communication may result in progressive cyanosis after the Fontan procedure. This problem has usually been treated surgically by ligation or re-inclusion of the residual hepatic vein in the Fontan circulation. Previous attempts at transcatheter closure of such veins have been unsuccessful. An Amplatzer septal occluder was successfully used for transcatheter closure of a post-Fontan hepatic vein to pulmonary venous atrium fistula in an 8 year old boy.

Occlusion of Fontan fenestrations using the Amplatzer septal occluder

OBJECTIVE

To evaluate the efficacy and safety of the Amplatzer septal occluder device for occlusion of Fontan fenestrations.

SUBJECTS

Five children aged 5-10 years who had undergone a fenestrated Fontan operation.

SETTING

Tertiary paediatric cardiology centre.

METHODS

Each patient had right and left heart catheterisation to assess haemodynamic suitability for fenestration closure. Sizing of the defect was achieved with a balloon wedge catheter and transoesphageal echocardiography. Transcatheter occlusion of the fenestration was accomplished using a 4 mm device in three patients, and 5 mm or 9 mm devices in the other two patients. Residual shunting following occlusion was assessed using angiography and echocardiography.

RESULTS

100% occlusion rate of the fenestration was achieved in all patients. No complications or device failures were seen during the three month follow up period.

CONCLUSION

The Amplatzer septal occluder device is safe, and effectively occludes the Fontan fenestration.

Catheter closure of moderate- to large-sized patent ductus arteriosus using the new Amplatzer duct occluder: immediate and short-term results

OBJECTIVES

The aim of this study was to assess the immediate and short-term results of anterograde catheter closure of a moderate- to large-sized patent ductus arteriosus (PDA) using the new self-expandable, respositionable Amplatzer duct occluder (ADO) device.

BACKGROUND

Transcatheter closure of a PDA using devices or coils is technically challenging and may be accompanied by a 38% incidence of residual shunts.

METHODS

Twenty-four patients (6 male, 18 female) underwent attempted transcatheter closure of a PDA using the ADO at a median age of 3.8 years (range 0.4 to 48) and a median weight of 15.5 kg (range 6 to 70). The mean PDA diameter at its narrowest segment was 3.7+/-1.5 mm. A 6F long sheath was used for delivery of the ADO. Follow-up evaluation was performed with color flow mapping of the main pulmonary artery within 24 h and at 1 and 3 months after closure.

RESULTS

Twenty three of the 24 patients had successful device placement. Angiography showed that 7 patients had complete immediate closure, 14 had a trace shunt (foaming through the device with no jet), and 2 had a small residual shunt (with a jet). Within 24 h, color Doppler revealed complete closure in all patients. The unsuccessful attempt was during an initial trial with a prototype that has been modified. The median fluoroscopy time was 13.5 min (range 6.3 to 47). All patients were discharged home the next day. There were no complications. Of the 23 patients, 21 completed the 1-month follow-up, all (95% confidence interval [CI] 86% to 100%) with complete closure, and 18 of 23 patients completed the 3-month follow-up, also all (95% CI 83% to 100%) with complete closure.

CONCLUSIONS

Anterograde transcatheter closure using the new ADO is an effective therapy for patients with a PDA diameter up to 6 mm. Further clinical trials are underway.

Balloon expandable stents for systemic venous pathway stenosis late after Mustard's operation

OBJECTIVES

Description and evaluation of current experience with the use of balloon expandable stents for the relief of systemic venous pathway stenosis late after Mustard's operation.

DESIGN

Retrospective observational study of technical procedures, angiographic, and haemodynamic findings.

PATIENTS

Twenty long term survivors of Mustard's operation for transposition of the great arteries (TGA) with angiographic evidence of systemic venous pathway narrowing.

INTERVENTION

Systemic venous pathway stenoses were stented using balloon expandable Palmaz stents.

RESULTS

Twenty seven stents were deployed across 24 stenoses. Seventeen stents were placed in the inferior baffle (16 patients), with an increase in mean (range) minimum diameter from 9.6 (4.5-15.9) to 16.5 (11.9-22.2) mm (p = 0.007), and a reduction in mean pressure gradient from 3.1 (0-8) to 0.67 (0-3) mm Hg (p = 0.002). Eight stents were placed in the superior pathways of eight patients, with diameters widened from 9.1 (3.5-14.1) to 15.2 (8.7-19.2) mm (p = 0.018), and gradients reduced from 6.4 (2-11) to 0.9 (0-2) mm Hg (p = 0.02). Two badly deployed stents were safely withdrawn from their intracardiac positions and redeployed in the iliac vein. Transvenous pacemaker insertion was facilitated by prior stent insertion.

CONCLUSIONS

The use of balloon expandable stents for late systemic pathway narrowing after Mustard's operation is safe and effective. The beneficial effects of stenting are likely to be more durable than those of balloon angioplasty alone, but longer term follow up is required.

Importance of right ventricular outflow tract angiography in distinguishing critical pulmonary stenosis from pulmonary atresia

OBJECTIVE

To investigate the spectrum of pulmonary atresia and critical pulmonary stenosis using right ventricular outflow tract angiography and explore its implications for catheter interventional treatment.

DESIGN

Prospective clinical study.

SETTING

Two paediatric cardiology centres.

SUBJECTS

11 neonates or infants (aged 1 day to 8 months; weighing 2.3 to 7.8 kg) with pulmonary atresia or where the differentiation of pulmonary atresia from critical pulmonary stenosis was unclear on either echocardiography or angiography.

METHODS

Right ventricular outflow tract angiography was performed on all patients to distinguish pulmonary atresia from critical pulmonary stenosis before opening the right ventricular outflow tract.

RESULTS

Right ventricular outflow tract angiography showed that three of seven patients diagnosed as pulmonary atresia by echocardiography had pin hole jets across the pulmonary valve; another had a probe patent valve that appeared imperforate on both echocardiography and right ventricular outflow tract angiography. Three of the four patients diagnosed by echocardiography as critical pulmonary stenosis were found on right ventricular outflow tract angiography to have pulmonary atresia. The remaining patient had such a tiny orifice that a second orifice had to be created with a radiofrequency catheter. The right ventricular outflow tract was opened successfully in 10 of the 11 patients, six of whom required application of radiofrequency energy. The right ventricular to aortic systolic pressure ratio fell from 1.4 (0.9 to 1.9) to 0.6 (0.2 to 1.1) (P < 0.05). All 11 patients were alive and well with transcutaneous oxygen saturations ranging from 84% to 95% at a median follow up duration of nine months.

CONCLUSIONS

Critical pulmonary stenosis and pulmonary atresia cannot always be accurately distinguished by echocardiography. Right ventricular outflow tract angiography helps to distinguish the two groups. In most cases the right ventricular outflow tract can be opened without mortality and with short to medium term survival.

Occlusion of congenital ventricular septal defects by the buttoned device. "Buttoned device" Clinical Trials International Register

OBJECTIVES

To study the feasibility of congenital ventricular septal defect occlusion by the buttoned device and to establish guidelines for its safe and effective application.

DESIGN

A descriptive study of all patients with a congenital ventricular septal defect undergoing transcatheter occlusion with the buttoned device, from March 1994 to May 1995. These patients were otherwise candidates for elective surgery at their institutions because they had persistence of a significant shunt (Qp:Qs = 1.5-2.1:1, median = 1.7), with left ventricular enlargement and/or symptoms, although their systolic pulmonary artery pressure was invariably normal (20-28 mm Hg, median = 25). The angiographic diameter of the defect ranged from 2.5 to 14 mm (median 6 mm).

SETTING

A multi-institutional study.

PATIENTS

Out of 25 cases attempted, 18 children and adults aged 4-35 years had devices implanted. Fifteen of these patients had membranous ventricular septal defects and three had muscular defects. All patients with a membranous ventricular septal defect had an associated aneurysm of the membranous septum.

INTERVENTIONS

The buttoned device was introduced either directly or, in the last 12 cases, over a wire bridging the femoral artery and the femoral or jugular vein; the devices were delivered through 7-9 French (F) long sheaths. A membranous defect was regarded as suitable for device closure if the distance from the centre of the defect to the insertion of the right coronary aortic valve leaflet was more than 50% of the size of the required device. The device was guided by echocardiography and fluoroscopy. All muscular defects were corrected through the right jugular vein and all membranous ones through the femoral vein.

RESULTS

All 18 patients underwent initial successful implantation of the device. In thirteen patients the shunts were completely occluded and in the remaining five there were trivial residual shunts. In two patients with membranous ventricular septal defects a change from the original position was noticed at two weeks; mild aortic regurgitation developed in one and the murmur recurred in the other; the devices had to be removed surgically. One patient developed transient third degree atrioventricular block during implantation; no tricuspid regurgitation was observed.

CONCLUSION

Clinical occlusion of congenital ventricular septal defects was achieved in 16 out of the 18 attempted cases (13 full occlusions). Membranous ventricular septal defect occlusion can be effective and safe if patients and device sizes are carefully selected.

Transcatheter occlusion of the patent ductus arteriosus with Cook detachable coils

OBJECTIVE

To report initial experience with a new occlusion device for native and residual patent ductus arteriosus.

DESIGN

Descriptive study of consecutive non-randomised patients undergoing a new method of patent ductus arteriosus closure with detachable coils.

SETTING

Tertiary centres for paediatric cardiology.

PATIENTS

71 consecutive patients, aged 1.2-22 years, with a patent ductus arteriosus (PDA) underwent elective transcatheter closure. 45 had native PDAs (group A) with a minimum diameter of 1.0 mm-5.0 mm (median 2.0 mm). A further 26 had undergone one or more previous occlusion attempts (group B).

INTERVENTIONS

A total of 133 detachable (Cook) spring coils were successfully implanted in 70 patients. The procedure was performed transvenously in 51 patients, retrograde arterially in 13, and by both routes in a further 6 patients. One 5 mm coil migrated but was successfully retrieved.

MAIN OUTCOME MEASURES

In group A colour flow Doppler echocardiography showed that complete occlusion was achieved in 40/45 (89%) at 24 hours, 41/45 (91%) at 1 month, and 44/45 (98%) by 6 months post procedure. Occlusion rates in residual PDAs were 22/25 (88%) occluded at 24 hours, 23/25 (92%) at 1 month, and 24/25 (96%) at 6 months follow up.

CONCLUSIONS

Transcatheter occlusion using detachable (Cook) spring coils is a safe and effective alternative to presently available devices. The delivery system allows full retrieval of the coil until a satisfactory position is obtained.

Single catheter approach for occlusion of a patent arterial duct with a Rashkind double umbrella

OBJECTIVES

To determine the benefits of using a single venous catheter and a single angiogram during catheter occlusion of a patient arterial duct with the Rashkind double umbrella compared with those of venous and arterial catheters and multiple angiograms.

DESIGN

Retrospective review of case notes.

PATIENTS

103 consecutive patients. The long sheath could not be advanced adequately in two patients. 101 patients had 104 implantations. Median (range) age was 35 (7-549) months and median (range) weight 13 (7-62) kg. Fifty four implantations were performed using the venous and arterial method and 50 using the venous only method.

RESULTS

Median procedure times (70 v 90 min), number of angiograms (one v four), and angiographic dye volume used (2 v 7 ml/kg) were significantly reduced using the venous only method compared with those of the venous and arterial method. There was no significant difference in fluoroscopy time (venous only 9 v venous and arterial 10 min).

CONCLUSIONS

Considerable improvements can be made in the technique of catheter closure of patent arterial ducts using the Rashkind double umbrella without compromising outcome using venous cannulation alone and a single angiogram, rather than venous and arterial cannulation and multiple angiograms. reduced risk to arteries from cannulation, The benefits are reduced radiation exposure, reduced risk to arteries from cannulation, shorter procedures, and lower equipment costs.

Responses of the post-term arterial duct to oxygen, prostaglandin E2, and the nitric oxide donor, 3-morpholinosydnonimine, in lambs and their clinical implications

BACKGROUND

Nitric oxide is a potent dilator of the pulmonary vasculature. There have been no previous reports on the action of nitric oxide on the arterial duct.

OBJECTIVES

To determine the responses of isolated post-term arterial duct rings from lambs to oxygen, prostaglandin E2 (PGE2) and the nitric oxide donor, 3-morpholinosydnonimine (SIN-1).

SETTING

Experimental laboratory.

SUBJECTS

Six neonatal lambs.

METHODS

Lambs aged 1-5 days were killed and the arterial duct and aorta excised and cut into rings. These were mounted on tension gauges in organ baths containing Krebs-Henseleit solution. Rings were exposed to increasing concentrations of oxygen, PGE2 and after preconstriction with potassium (40 mmol/l) to SIN-1. Tension and relaxation responses were recorded.

RESULTS

Increased oxygen tension resulted in increased tension in the ductal rings above 88.9 mm Hg as previously described. No response to PGE2 occurred before or after ductal rings were exposed to oxygen. SIN-1 caused relaxation of smooth muscle in the arterial duct to a similar degree as that in the aortic rings.

CONCLUSIONS

As previously shown, oxygen is a potent constrictor of the arterial duct. The post-term arterial duct does not relax in response to PGE2 possibly as a result of inactivation by oxygen of the special sensitivity of the duct to PGE2. SIN-1 is a potent smooth muscle relaxing agent in the term arterial duct and may have a role in the initial management of neonates with duct dependent pulmonary circulation.

Radiofrequency thermal angioplasty maintains arterial duct patency. An experimental study

BACKGROUND

Long-term maintenance of arterial duct patency by a catheter technique would be a valuable nonsurgical method of palliation for duct-dependent circulations. We used a new method: percutaneous radiofrequency thermal balloon angioplasty of neonatal lamb arterial ducts.

METHODS AND RESULTS

Radiofrequency balloons 5 or 6 mm in diameter were introduced via the femoral vein of 32 neonatal lambs and inflated to 4 atm. In 28, a radiofrequency generator was used to heat the saline/contrast mixture in the balloon to 65 degrees C (n = 2), 75 degrees C (n = 2), 85 degrees C (n = 10), 100 degrees C (n = 8), and 120 degrees C (n = 6). In 4 lambs, angioplasty alone was performed. Lambs were recatheterized to assess patency at intervals up to 78 weeks. Immediate results showed the arterial duct to be patent in all cases, with a mean rise in systolic pulmonary artery pressure of 13 +/- 8 mm Hg and a mean rise in pulmonary artery oxygen saturation of 12 +/- 15%. With a mean follow-up of 45.7 +/- 28 weeks, 3 of the 4 (75%) angioplasty alone ducts closed, but only 5 of the 28 (18%) radiofrequency-treated ducts (P < .05). The mean rise in oxygen saturation between the superior vena cava and the pulmonary artery was 7.6 +/- 7% at last follow-up. Follow-up angiography of the arterial ducts showed the development of stenoses in all patent ducts.

CONCLUSIONS

Radiofrequency thermal balloon angioplasty leads to long-term arterial duct patency in lambs in > 80% of the treated group and is significantly more effective than balloon angioplasty alone.

Arterial duct morphology with reference to angioplasty and stenting

We studied the angiographic morphology of the arterial duct in neonates with congenital heart diseases. We defined the variations in ducto-aortic angle, number of tortuosities and site of insertion into the aorta of the duct in five diagnostic groups: (i) patent arterial duct (unobstructed) (n = 27), (ii) coarctation of the aorta (n = 24), (iii) pulmonary stenosis (n = 23), (iv) pulmonary atresia (n = 19) with or without ventricular septal defect, (v) hypoplastic left heart syndrome (n = 3). In the patent arterial duct group the angles ranged from 80 to 139 degrees, mean 107 degrees; in the coarctation group, 76 to 136 degrees, mean 104 degrees; in the pulmonary stenosis group, -60 to 111 degrees, mean 43 degrees; in the pulmonary atresia group, -55 to 115 degrees, mean 25 degrees; in the hypoplastic left heart syndrome 92 to 105 degrees, mean 98 degrees. The angles for the pulmonary atresia and stenosis groups were significantly less than those for the coarctation and patent ductus groups (P < 0.001). A ventricular septal defect in patients with pulmonary atresia or pulmonary stenosis was significantly associated with a smaller angle, a more proximal and a more tortuous duct (P < 0.01). The varying morphology of the duct in neonates with congenital heart lesions, especially with right heart obstruction requires special attention when attempting catheter techniques of ductal stenting. In particular the angle of approach and the presence of tortuosities may increase the difficulty of endovacular stenting.

Arterial duct angioplasty as an adjunct to dilatation of the valve for critical pulmonary stenosis

OBJECTIVE

To assess the efficacy of arterial duct angioplasty in maintaining adequate ductal patency in neonates with critical pulmonary valve stenosis.

PATIENTS

Two neonates presenting with cyanosis due to critical pulmonary valve stenosis with severe right ventricular hypoplasia underwent percutaneous balloon dilatation of the pulmonary valve. Despite successful dilatation, both remained cyanosed while receiving prostaglandin E2 infusions.

RESULTS

Angioplasty of the arterial duct resulted in increased arterial oxygen saturations. Adequate arterial duct patency was maintained for three months during which time right ventricular dimensions increased enough to allow sufficient pulmonary circulation without the duct.

CONCLUSIONS

Arterial duct angioplasty is an effective additional treatment for patients with critical pulmonary valve stenosis whose right ventricle is too small to provide adequate forward flow after balloon dilatation of the valve. Arterial duct angioplasty sustains adequate patency of the duct while the right ventricle grows sufficiently to undertake the pulmonary circulation.

Balloon dilatation of the arterial duct in congenital heart disease

The systemic circulation of newborn infants with congenital left-heart obstruction is supplied from the right ventricle via a patent arterial duct between the pulmonary artery and descending aorta. The duct closes during the first few days of life, but infusion of prostaglandin E2 can prevent closure in some cases. We report four newborn infants (aged 3-8 days) with intractable heart failure due to severe obstruction of the left heart in the presence of a closing arterial duct. Infusion of prostaglandin E2 did not improve their clinical condition. Cardiac catheterisation and balloon dilatation of their arterial ducts resulted in a dramatic improvement in the babies' clinical condition; during subsequent surgical repair of the infants' hearts, the arterial ducts were found to be widely patent. Balloon dilatation gives immediate and sustained wide patency of the arterial duct in infants who do not respond adequately to prostaglandin E2.

Atrial natriuretic peptide response to rapid atrial pacing in cardiac-denervated dogs

The effects of rapid atrial pacing on central hemodynamics, plasma hormones, and renal function were investigated in eight control and nine cardiac-denervated dogs under chloralose anesthesia. Pacing at approximately 250 ppm for 60 min caused similar increases in pulmonary wedge and right atrial pressures, systemic vascular resistance, and plasma atrial natriuretic peptide (ANP) in both groups. In control dogs, pacing produced a fall in both plasma vasopressin (AVP) and plasma renin activity (PRA) and a rise in urine flow rate associated with an increase in free water but not sodium clearance. In contrast, in cardiac-denervated dogs, both plasma AVP and PRA increased during pacing; urine flow rate did not change, and marked sodium retention occurred. This study supports the concept that the increase in urine flow during rapid atrial pacing is mediated by inhibition of renin and AVP secretion through intact cardiac nerves. The secretion of ANP is unaffected by cardiac denervation. The natriuretic and vasodilator actions of high plasma ANP concentrations during rapid atrial pacing can be inhibited either by neurally mediated cardiorenal effects in normal animals or by stimulation of the renin-angiotensin system after cardiac denervation.

Atrial natriuretic peptide inhibits postural release of renin and vasopressin in humans

The effects of infusions of atrial natriuretic peptide (ANP) on the hormonal and hemodynamic responses to head-up tilt were investigated in six healthy adults. Head-up tilt at 45 degrees for 2 h during placebo saline infusion caused a 7% fall in blood volume accompanied by increases in plasma renin activity (PRA) and plasma arginine vasopressin (AVP) of 112 and 175%, respectively. Head-up tilt was repeated during an infusion of ANP producing a four- to sixfold increase in plasma ANP concentrations. This resulted in an 18% fall in plasma volume, yet despite this greater fall in plasma volume, PRA did not change. Two subjects experienced vasovagal symptoms toward the end of the ANP infusions accompanied by large increases in plasma AVP. In the other four subjects, plasma AVP remained unchanged during ANP infusions. Both procedures resulted in similar increases in plasma norepinephrine levels and in heart rate. Infusion of ANP prevents the posturally stimulated release of renin and AVP.

Role of atrial pressure and rate in release of atrial natriuretic peptide

To investigate whether atrial natriuretic peptide (ANP) release during paroxysmal tachycardia is due to increased atrial rate or increased atrial pressure, plasma ANP concentrations were measured during atrial pacing at increasing rates in six alpha-chloralose-anesthetized dogs whose atrial pressures were maintained artificially low by balloon occlusion of the inferior vena cava (IVC). These ANP concentrations were compared with those seen during identical increasing atrial rates in the same dogs without IVC occlusion. During incremental pacing without IVC occlusion, pulmonary wedge pressure (PWP; mean +/- SE) rose progressively from 5.3 +/- 1.6 at 200 to 20.2 +/- 2.3 mmHg at 350 beats/min (P less than 0.01), and right atrial pressure (RAP) rose progressively from 2.5 +/- 0.9 at 200 to 6.7 +/- 2.1 mmHg at 350 beats/min (P less than 0.05). At the same time, arterial and coronary sinus ANP concentrations rose from 116 +/- 55 and 339 +/- 91 to 1,126 +/- 226 and 1,960 +/- 456 pmol/l, respectively (P less than 0.01). In contrast, incremental pacing with IVC occlusion produced no significant increase in PWP and RAP. Arterial and coronary sinus ANP concentrations during IVC occlusion were, respectively, 208 +/- 126 and 388 +/- 159 at 200 and 261 +/- 83 and 345 +/- 80 pmol/l at 350 beats/min (NS). This study demonstrates that the release of ANP during tachycardia is primarily dependent on increased atrial pressure and not atrial rate.

Rebound increase in plasma renin and vasopressin following graded infusions of atrial natriuretic peptide in man

The effects of graded infusions of atrial natriuretic peptide (ANP) on hemodynamics, renal function, plasma renin activity (PRA) and plasma arginine vasopressin (AVP) were investigated in a two part study in 6 volunteers. Three 30-min iv infusions of either saline control or ANP at graded rates of 4, 10 and 40 pmol kg-1 min-1 were given. ANP infusions were associated with a significant increase in sodium clearance from 1.08 +/- 0.21 to 2.83 +/- 0.50 ml/min, an increase in hematocrit and a net fluid loss. Plasma AVP remained constant during ANP infusions but increased significantly afterwards when plasma ANP concentrations were falling rapidly, and this was accompanied by marked antidiuresis. PRA fell by 23% during the saline control infusions and by 50% during ANP infusions. Following cessation of ANP infusions there was a significant rebound increase in PRA. No changes were observed in blood pressure, heart rate, glomerular filtration rate or renal plasma flow. These results suggest an interaction in man between ANP and the hormones renin and AVP.

Effects of endogenous atrial natriuretic peptide released by rapid atrial pacing in dogs

The relationships between the hemodynamic, renal, and endocrine changes induced by rapid atrial pacing were studied in seven chloralose-anesthetized greyhounds paced from the right atrial appendage for 60 min at 250 beats/min. Pacing increased mean pulmonary wedge pressure, decreased cardiac output, and decreased mean arterial pressure. Systemic vascular resistance did not change significantly. Coronary sinus atrial natriuretic peptide (ANP) concentrations rose maximally within 5 min of commencing pacing. The corresponding increase in arterial ANP concentrations during this time was only 44% of its maximum value after 30 min of pacing. Plasma concentrations of arginine vasopressin were unchanged. Plasma renin activity decreased during pacing and showed a marked rebound increase at 60 min postpacing. Plasma norepinephrine levels did not change significantly during pacing. Urine flow increased during the latter 30 min of pacing. There was no significant change in sodium clearance despite high sustained concentrations of ANP. The lack of significant natriuretic and systemic vasodilator effects in association with high arterial plasma concentrations of endogenous ANP, in the absence of antagonistic mechanisms, suggests that the natriuretic and vascular effects of ANP may not be its major physiological actions.