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Biomedical subjects

K P Walsh

Publications and source records attributed to K P Walsh.

At least 19 recordsLinked to original sources
PubMed2006

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.

Anti-Inflammatory Agents↗
PubMed2005

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.

Adult↗
PubMed2004

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.

Adult↗
PubMed2001

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.

Case-Control Studies↗
PubMed2000

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.

Cardiac Catheterization↗
PubMed2000

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.

Adolescent↗
PubMed2000

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.

Actinobacteria↗
PubMed2000

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.

Cardiac Catheterization↗
PubMed2000

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.

Anesthetics, Dissociative↗
PubMed1999

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.

Adolescent↗
PubMed1999

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.

Adult↗
PubMed1999

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.

Cardiac Catheterization↗
PubMed1999

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.

Adolescent↗
PubMed1998

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.

Alloys↗
PubMed1998

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.

Adolescent↗
PubMed1998

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.

Angiography↗
PubMed1998

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.

Cardiac Catheterization↗