Robin P. Martin

Radiofrequency-assisted balloon dilatation in patients with pulmonary valve atresia and an intact ventricular septum.

OBJECTIVE--To investigate the efficacy and safety of transcatheter radiofrequency-assisted valve dilatation for infants with pulmonary valve atresia and intact ventricular septum as an alternative to the use of laser heated wires. DESIGN--Prospective clinical study. SETTING--Three paediatric cardiology centres. PATIENTS--Four children (aged 5-101 days, weight 2.8 kg) with pulmonary valve atresia and intact ventricular septum underwent percutaneous radiofrequency-assisted valve dilatation. METHODS--After delineating the atretic valve by angiography, 0.020 inch or 0.018 inch radiofrequency wires were used to perforate the atretic valve. The valve was then dilated with conventional balloon dilatation catheters up to the valve annulus diameter. RESULTS--In all four cases the radiofrequency wire perforated the atretic pulmonary valve and balloon dilatation was successful. In one patient the radiofrequency wire also passed through the anterior wall of the pulmonary artery causing tamponade which required surgical repair shortly afterwards. This patient died from sepsis six days later. One patient died three weeks after the procedure from septicaemia and a paradoxical coronary embolus. Two patients were discharged after 4 and 14 days respectively. CONCLUSIONS--Radiofrequency-assisted valve dilatation is a promising alternative to the recently developed laser wire technique. The major advantages are a reduction in cost and improved safety for the staff performing the procedure.

Total UK multi-centre experience with a novel arterial occlusion device (Duct Occlud pfm).

OBJECTIVE: To report the total UK multicentre experience of a novel arterial occlusion device (Duct Occlud pfm). DESIGN: Descriptive study of selected non-randomised paediatric patients with a variety of aortopulmonary connections. SETTING: Five UK tertiary referral centres for congenital heart disease. PATIENTS AND METHODS: Between March 1994 and February 1995, 57 children aged 2 weeks to 14 years (median 50 months) underwent attempted closure of their aortopulmonary connection. Fifty one had persistent arterial ducts and 9 of them had had a Rashkind umbrella device implanted. Five patients had superfluous modified Blalock-Taussig shunts (mBTS). In one there was also a native major aortopulmonary collateral artery (MAPCA). Another patient had a native major aortopulmonary connection (APC). Transcatheter occlusion was attempted in all cases through a 4 F delivery catheter. RESULTS: Devices were successfully deployed in 49/57 (86%) patients. Seven of 51 cases with persistent arterial ducts were judged too large for the device and a Rashkind umbrella was used. 40 (91%) of the 44 in whom the detachable coil device was used had complete occlusion at 24 hours on colour flow Doppler echocardiography. Devices were successfully deployed in all 6 remaining patients (4 mBTS, 1 mBTS + MAPCA, and 1 APC). Embolisation of a device occurred on 4 occasions. Two devices were not retrieved but caused no apparent clinical problems. CONCLUSION: This novel detachable coil type occlusion system compares favourably with other methods of transcatheter occlusion of native, residual, or surgically created aortopulmonary shunts. The delivery system allows its use in small children.

Balloon expandable stent implantation for native and recurrent coarctation of the aorta—prospective computed tomography assessment of stent integrity, aneurysm formation and stenosis relief

Background Stenting for aortic coarctation is known to be effective in the medium term. Aneurysm formation following stent implantation is a recognised complication. However, data regarding aortic wall injury and stent integrity following stent placement are sparse. Objectives We report comprehensive clinical, echocardiographic and prospective CT follow-up data following stenting for aortic coarctation from a single centre. Methods Full data analysis of all patients undergoing balloon expandable stent implantation and follow-up procedures in a single tertiary congenital cardiac unit. Results Between October 2002 and April 2008, we performed 102 coarctation stent procedures on 88 patients. Median age was 20.6 years (range 8.5–65) and median weight 65 kg (range 34–101). 94 stents (26 covered) were implanted. 12 procedures were re-dilatations. Stenting resulted in a reduction of the gradient across the site of coarctation, from a median of 20 mm Hg to 4 mm Hg. There were no procedure-related deaths. Four patients had immediate complications (one requiring emergency surgery). During median follow-up of 34.5 months (range 4.2–72.8), two patients had late complications requiring additional stent procedures. Follow-up CT data are available in 84 patients with MRI in one patient (96.5%). Only one patient developed a procedure-related aortic aneurysm. All stent fractures (n=7) occurred with a single stent design. Conclusions Stenting for aortic coarctation and re-coarctation is effective with low immediate complication rates. CT is useful in the longer term for assessment of stent integrity and post-procedural aneurysm formation. Overall incidence of post-procedural aneurysm is rare and stent fractures were not seen with newer generation stents.

Influence of anatomic correction for transposition of the great arteries on myocardial perfusion: Radionuclide imaging with technetium-99m 2-methoxy isobutyl isonitrile

OBJECTIVES We sought to determine the incidence of late perfusion defects attributable to coronary artery mobilization in patients undergoing anatomic correction for complete transposition of the great arteries. BACKGROUND Anatomic correction (arterial switch procedure) is currently the surgical treatment of choice for complete transposition. From its conception, there has been concern about the impact on myocardial perfusion of the coronary artery mobilization and reimplantation involved in the correction. Previous studies have demonstrated myocardial perfusion defects in patients after correction, although a causal relation between coronary mobilization, and perfusion abnormality has not been established. METHODS In a case-comparison study designed to test this hypothesis, 29 children underwent imaging with technetium-99m 2-methoxy isobutyl isonitrile (technetium-99m mibi). Ten had undergone anatomic correction (arterial switch group; interval from operation 6.9 +/- 1.42 years [range 4.9 to 9.1]); 9 had required noncoronary open heart surgery for other cardiac lesions (post-bypass group; interval from operation 5.6 +/- 3.6 years [range 1.0 to 13.25]); and 10 had had no surgical procedure (control group). The latter group comprised children with atrial or ventricular septal defects who required a radionuclide study for shunt calculation. Planar studies were performed in all 29 children, and additional tomographic acquisition was achieved in 25. To assess reversibility of perfusion defects both an exercise and a rest planar study were performed in the arterial switch group. RESULTS Perfusion abnormalities were observed in seven of the nine children in the postbypass group and in all 10 children in the arterial switch group. The frequency of perfusion defects in these two groups was similar, with at least 25% of the tomographic segments reported being abnormal. The control group had significantly fewer defects than the other two groups (p = 0.02), with only 8% of the tomographic segments judged to be abnormal. In all except one patient in the arterial switch group, the segments reported as abnormal on the planar exercise study were either abnormal or equivocal on the rest study, indicating a fixed abnormality. CONCLUSIONS Although the precise etiology of these perfusion abnormalities cannot be defined from this study, these data suggest that their origin is related more to the insult of open heart surgery itself than to the coronary manipulation involved in the arterial switch procedure. The functional importance requires further study.

Self‐expanding and balloon expandable covered stents in the treatment of aortic coarctation with or without aneurysm formation

Objectives: We describe our complete experience with covered stent implantation for aortic coarctation including short‐ to medium‐term outcomes. Background: Coarctation of the aorta is a heterogeneous disease process with multiple associated complications both with and without treatment. Covered stents have evolved to provide greater support to the aortic wall and a varied approach with choice of stent tailored to the anatomy of the patient is required. Methods: We retrospectively analyzed consecutive patient data from two congenital heart centers from March 2003 to October 2007. Results: We implanted 38 covered stents in 37 patients (20 female) of which three were self‐expanding stents. Median age was 29.6 years (9–65) with median weight of 71.5 kg (35–95). The indications for stent placement were native coarctation (n = 13); recurrent coarctation following surgical treatment (n = 11); aneurysm associated with previous coarctation surgery (n = 7); aorto‐bronchial fistula leading to acute hemoptysis (n = 2); stent fracture (n = 1); associated arterial duct (n = 2). One patient had a combination of acquired coarctation and false aneurysm. The median screening time was 10 min (3–22). The median systolic gradient of 26 mm Hg (10–60) was reduced to 4 mm Hg (0–20) postprocedure (P < 0.001). There were no deaths on median follow up of 11.5 months (1–56). One patient developed aortic rupture during the procedure and required emergency surgery. Conclusion: Covered stent implantation for treatment of aortic coarctation is safe and highly effective in selected patients. Self‐expanding stent grafts may be preferable to balloon expandable stents when there is aneurysm formation in the setting of aortopathy.

Early clinical experience with the new Amplatzer Ductal Occluder II for closure of the persistent arterial duct.

Objectives: To describe the early single‐center clinical experience with the Amplatzer Ductal Occluder II (ADO II). Methods: All patients undergoing attempted transcatheter closure of persistent arterial duct (PDA) with the ADO II were included. Data collected included demographic, clinical, and echocardiographic parameters. Results: From March until September 2008, 29 procedures were undertaken in 27 patients (21 female). Median age was 1.4 years (range 0.4–76 years) with median weight 9.4 kg (range 4.7–108 kg). A transarterial approach was used in 2 patients. The median minimum ductal diameter was 2.7 mm (range 1.7–5). ADO II was released in 25 patients (92.5%). Two patients had significant residual shunting following deployment of ADO II and underwent closure with Amplatzer ductal occluder (ADO I). Postprocedural echocardiography identified one occluder had changed position with development of a significant leak and one occluder had embolized to the left pulmonary artery. Both occluders were retrieved successfully at a second catheter procedure. Complete occlusion was noted predischarge in 22 of the remaining 23 occluders (96%). One patient had mild flow acceleration in the left pulmonary artery which has resolved. Conclusions: The ADO II is highly effective at providing rapid occlusion of morphologically varied PDAs. Occluder design allows closure with arterial or venous approach and delivery with 4 or 5 F delivery catheters. Stable occluder position is dependent on correct positioning of both aortic and pulmonary discs. A larger range of sizes and configurations of this occluder may be required to successfully occlude all ductal sizes and morphologies.

A quantitative evaluation of aortic regurgitation after anatomic correction of transposition of the great arteries.

Twenty patients who had undergone anatomic correction of transposition of the great arteries were assessed by Doppler echocardiography or cardiac catheterization, or both, to identify the presence of aortic regurgitation. The severity of aortic regurgitation was evaluated by radionuclide angiographic measurement of the stroke volume index a mean of 47.1 months postoperatively. The stroke volume index was defined as the ratio of the stroke counts between the left and right ventricles. A value greater than 1.8 was considered to indicate significant left ventricular volume overload. Eight patients (40%) were shown to have various degrees of aortic regurgitation by Doppler echocardiography or cardiac catheterization, or both. The mean (+/- SD) stroke volume index was 1.03 +/- 0.15 in these patients and 1.01 +/- 0.21 in the 12 patients without aortic regurgitation (p = NS). The stroke volume index was not above the normal range in any patient, indicating that the degree of aortic regurgitation present was trivial. This medium-term study indicates that trivial or mild aortic regurgitation is a frequent finding after anatomic correction of transposition of the great arteries. However, it rarely results in an audible cardiac murmur or significant left ventricular volume overload. Long-term evaluation is required to determine its importance.

Relationship of aortic pulse wave velocity and baroreceptor reflex sensitivity to blood pressure control in patients with repaired coarctation of the aorta

BACKGROUND Increased aortic stiffness and reduced baroreceptor reflex sensitivity have been described independently after coarctation of the aorta (CoA) repair. This study sought to determine the relationship between these variables and blood pressure control in adolescents after early CoA repair. METHODS Spontaneous baroreceptor reflex sensitivity (sBRS) and aortic pulse wave velocity (PWV) were measured in 29 adolescents after CoA repair and compared with 20 age-matched controls. Patients treated for hypertension or having residual aortic narrowing were excluded. Ambulatory blood pressure (ABP), heart rate variability, and cardiac output were also recorded. After ABP measurement, CoA subjects were classified as normotensive or hypertensive. RESULTS Nine patients (31%) were hypertensive according to standard definitions, and this subgroup had higher aortic PWV than the normotensive subgroup (P = .004). There was a significant positive correlation between ABP and PWV seen in the whole CoA group (r(2) = 0.5, P < .01). The normotensive subgroup had increased sBRS compared with controls (P = .02). This difference was not seen between the hypertensive subgroup and controls. There was a significant inverse relationship between sBRS and aortic PWV in the whole CoA group (r(2) = 0.25, P = .01). The normotensive subgroup had a significant reduction in stroke index compared with controls (P = .02), which was not seen in the hypertensive subgroup (P = .96). CONCLUSIONS Adolescents with hypertension after CoA repair have increased aortic PWV and a relative reduction in sBRS compared with normotensive CoA patients. Thus, failure of the baroreceptor reflex to compensate for increasing arterial stiffness may herald the onset of hypertension in these patients.

Early clinical experience with a modified amplatzer ductal occluder for transcatheter arterial duct occlusion in infants and small children

To describe early clinical experience with the amplatzer ductal occluder II additional sizes (ADO II AS) for percutaneous arterial duct occlusion in infants and small children.

When to close a patent foramen ovale.

Transcatheter closure of the patent foramen ovale was the most common interventional procedure performed in our adult congenital heart disease unit in 2006. Although the prevalence of patent foramen ovale is similar in children, closure is rarely performed in this group despite susceptibility to similar defect-related morbidity. In this review we question whether this should remain the case.