Bjoern Peters

Percutaneous pulmonary valve implantation: two-centre experience with more than 100 patients

AIMS Dysfunction of valved conduits in the right ventricular outflow tract (RVOT) limits durability and enforces repeated surgical interventions. We report on our combined two-centre experience with percutaneous pulmonary valve implantation (PPVI). METHODS AND RESULTS One hundred and two patients with RVOT dysfunction [median weight: 63 kg (54.2-75.9 kg), median age: 21.5 years (16.2-30.1 years), diagnoses: TOF/PA 61, TAC 14, TGA 9, other 10, AoS post-Ross-OP 8] were scheduled for PPVI since December 2006. Percutaneous pulmonary valve implantation was performed in all patients. Pre-stenting of the RVOT was done in 97 patients (95%). The median peak systolic RVOT gradient decreased from 37 mmHg (29-46 mmHg) to 14 mmHg (9-17 mmHg, P < 0.001) and the ratio RV pressure/AoP decreased from 62% (53-76%) to 36% (30-42%, P < 0.0001). The median end-diastolic RV-volume index (MRI) decreased from 106 mL/m(2) (93-133 mL/m(2)) to 90 mL/m(2) (71-108 mL/m(2), P = 0.001). Pulmonary regurgitation was significantly reduced in all patients. One patient died due to compression of the left coronary artery. The incidence of stent fractures was 5 of 102 (5%). During follow-up [median: 352 days (99-390 days)] one percutaneous valve had to be removed surgically 6 months after implantation due to bacterial endocarditis. In 8 of 102 patients, a repeated dilatation of the valve was done due to a significant residual systolic pressure gradient, which resulted in a valve-in-valve procedure in four. CONCLUSION This study shows that PPVI is feasible and it improves the haemodynamics in a selected patient collective. Apart from one coronary compression, the rate of complications at short-term follow-up was low. Percutaneous pulmonary valve implantation can be performed by experienced interventionalists with similar results as originally published. The intervention is technically challenging and longer clinical follow-up is needed.

Left ventricular conditioning in the elderly patient to prevent congestive heart failure after transcatheter closure of atrial septal defect

Transcatheter closure of atrial septal defects (ASDs) is a safe and effective treatment. Over the past years, an increasing number of elderly patients (age > 60 years) have been admitted for transcatheter closure to prevent ongoing congestive heart failure from volume overload. However, recent data point to the risk of serious acute left ventricular dysfunction leading to pulmonary edema immediately after surgical or transcatheter ASD closure in some patients. In this study, we used a technique described before to recognize in advance patients at risk of left heart failure after ASD closure. Those patients at risk were then treated with preventive conditioning medication for 48–72 hr before definitive transcatheter ASD closure was performed. Fifty‐nine patients aged over 60 years (range, 60–81.8 years; median, 68 years) were admitted to our institution for transcatheter closure of an atrial septal defect. All patients received evaluation of atrial pressures before and during temporary balloon occlusion of the ASD. Patients with left ventricular restriction due to increased mean atrial pressures (> 10 mm Hg) during ASD occlusion received anticongestive conditioning medication with i.v. dopamine, milrinone, and furosemide for 48–72 hr before definitive ASD closure with an Amplatzer septal occluder was performed. In 44 patients without any signs of left ventricular restriction, ASD closure was performed within the first session. Fifteen (25%) out of 59 patients showed left ventricular restriction. In the majority of patients with LV restriction, the mean left atrial pressures with occluded ASD were significantly decreased after 48–72 hr of conditioning medication. Definitive ASD closure was then performed in a second session. Only two patients received a fenestrated 32 mm Amplatzer occluder due to persistent increased atrial pressures > 10 mm Hg even after conditioning medication. There were no significant differences in shunt, device size, or defect size between the two groups. Balloon occlusion of atrial septal defects identifies patients with left ventricular restrictive physiology before ASD closure. Intravenous anticongestive conditioning medication seems to be highly effective in preventing congestive heart failure after interventional closure of an ASD in the elderly patient with a restrictive left ventricle. Catheter Cardiovasc Interv 2005;64:333–337.

Transcatheter therapy of long extreme subatretic aortic coarctations with covered stents

We report our experience with the transcatheter treatment of long extreme subatretic coarctations in four adult patients by the implantation of covered stents. The minimal narrowing of the stenosis was 0.014″ to 2 mm; the hypoplastic distance measured between 21 and 42 mm. Polytetrafluoroethylene‐covered stents 39–50 mm long were implanted and 6 months later redilated. Residual pressure gradients ranged from 0 to 10 mm Hg. One stent fracture required the implantation of a second stent after 6 months. The follow‐up period ranges from 18 to 4 months and has been uneventful so far. Covered stents seem to have the potential to extend the limits of interventional therapy to extreme forms of aortic coarctations. Catheter Cardiovasc Interv 2004;63:236–239.

The role of stents in the treatment of congenital heart disease: Current status and future perspectives.

Intravascular or intracardiac stenoses occur in many forms of congenital heart disease (CHD). Therefore, the implantation of stents has become an accepted interventional procedure for stenotic lesions in pediatric cardiology. Furthermore, stents are know to be used to exclude vessel aneurysm or to ensure patency of existing or newly created intracardiac communications. With the further refinement of the first generation of devices, a variety of “modern” stents with different design characteristics have evolved. Despite the tremendous technical improvement over the last 20 years, the “ideal stent” has not yet been developed. Therefore, the pediatric interventionalist has to decide which stent is suitable for each lesion. On this basis, currently available stents are discussed in regard to their advantages and disadvantages for common application in CHD. New concepts and designs developed to overcome some of the existing problems, like the failure of adaptation to somatic growth, are presented. Thus, in the future, biodegradable or growth stents might replace the currently used generation of stents. This might truly lead to widening indications for the use of stents in the treatment of CHD.

Early and mid-term results with the growth stent—A possible concept for transcatheter treatment of aortic coarctation from infancy to adulthood by stent implantation?

Aims: Evaluation of the Growth Stent—a stent consisting of two stent halves connected by reabsorbable sutures—for the treatment of aortic coarctation in infants. Methods and Results: Surveillance study of 13 Growth Stents implanted in 12 patients aged 1–15 months (median 5 months). Body weight ranged from 3.4–12.8 kg (median 5.4 kg). Eight patients suffered from aortic (re‐)coarctation, four of them from stenosis of the aortic anastomosis after a Norwood I procedure. The follow‐up period was 24 months (11–51 months). Pressure gradients immediately after stent implantation decreased from 30 mm Hg (range 20–50 mm Hg) to 8 mm Hg (range 0–15 mm Hg). Five patients had one (3 pts) or two (2 pts) balloon dilations 3–28 months (median 12 months) after Growth Stent implantation. The median pressure gradient decreased from 25 mm Hg (range 15–30 mm Hg) to 15 mm Hg (range 5–25 mm Hg). Six patients received a large stent after 19–34 months. Median body weight was 11.8 kg (9.4–15 kg). Conclusions: The Growth Stent is suitable for the acute treatment of aortic coarctation in infants and can be overstented later on—if necessary—with a larger stent without causing restriction.

Feasibility and efficacy of stent redilatation in aortic coarctation

Objectives: We evaluated the efficacy and safety of stent redilation in patients with aortic coarctation (COA). Methods and Results: In our retrospective study of 28 stent redilation procedures on 22 patients, the interval between implantation and redilation ranged from 2.5 month to 11 years (median 18 months). Ten patients had native COAs, one had repaired interrupted aortic arch. The remaining patients had residual COAs after surgery. Stent redilation was successful in 26 procedures. Pressure gradients decreased from a mean of 26 ± 13.8 mm Hg to 7.9 ± 6.52 mm Hg (P < 0.001). The mean diameter of the stents increased from 9.19 ± 3.29 mm to 12.1 ± 3.68 mm (P < 0.001). In a patient with Williams‐Beuren syndrome, massive neointimal proliferation made stent redilation impossible. One other patient developed aortic aneurysm after redilation and was operated after 3 years. Conclusions: Stent redilation for aortic COA is a safe and successful procedure.

Transcatheter creation of an aortopulmonary shunt in an animal model.

The surgical creation of an aortopulmonary shunt is an important tool in the therapy of complex congenital heart defects. We report on a transcatheter approach to establish an aortopulmonary shunt in piglets.

Coronary Flow Reserve Measurement Detects Transplant Coronary Artery Disease in Pediatric Heart Transplant Patients

BACKGROUND Cardiac allograft vasculopathy (CAV) in patients who have undergone heart transplantation leads to graft dysfunction and is still the major concern for long-term survival. Evaluation of coronary flow velocity reserve (CFR) has been established for diagnosis of CAV. Systemic application of adenosine vs intracoronary testing for CFR has been validated in adults; however, its accuracy in pediatric patients has not yet been proven. METHODS CFR was prospectively measured in 33 clinically asymptomatic pediatric heart transplant recipients. CFR measurements were made in the left anterior descending (LAD) artery using a 0.014-inch Doppler FloWire (Cardiometrics). CFR was defined as the ratio of hyperemic (after adenosine injection) to basal (before adenosine) average peak velocity (APV). Adenosine (Adrekar) was administered by intracoronary (15 or 30 mug bolus) and systemic (0.1 mg/kg) injection in each patient. Epicardial CAV was evaluated in coronary angiograms (Stanford criteria) and microvasculopathy was diagnosed in endomyocardial biopsies (evidence of luminal stenosis) blinded to clinical data. RESULTS Thirty-three patients were included in this study. Their median age (range) was 11.9 (1.4 to 17) years and median post-transplant time 4.3 (1 to 11.7) years. Seventeen of the 33 patients had epicardial CAV (mainly peripheral obliterations or B1 and B2 lesions) and microvascular CAV. Epicardial CAV only was found in 4 patients and microvasculopathy only was present in only 1 patient. CFR was significantly reduced in patients with epicardial CAV and microvasculopathy when compared with patients without any signs of CAV: 206 +/- 53 vs 276 +/- 39 (p < 0.001) for the systemic application and 213 +/- 50 vs 271 +/- 45 (p = 0.004) for the intracoronary application. CONCLUSIONS CFR and coronary vasoreactivity to adenosine are decreased in pediatric patients with CAV and correlate with histopathologic and angiographic evidence of microvascular disease. Measurement of CFR with intracoronary and systemic application of adenosine is comparable, while systemic application is necessary for non-invasive measurement of CFR in pediatric patients.

Preliminary experience with a new 18 mm Amplatzer PFO occluder for small persistent foramen ovale.

We report our initial experience with a new 18 mm Amplatzer PFO device for the closure of small PFO. Patients were selected by a semiquantitative sizing procedure using the circle of a diagnostic pigtail catheter instead of a sizing balloon. In all eight patients, the device was easy to implant without problems. Due to its size, it has the potential to minimize the risk of inadvertent atrial erosion or perforation after deployment and thus will enhance the safety of interventional PFO closure. Cathet Cardiovasc Intervent 2003;59:518–521.

Rare case of pulmonary arteriovenous fistula simulating residual defect after transcatheter closure of patent foramen ovale for recurrent paradoxical embolism

We report on a patient suffering from recurrent cerebrovascular events despite previous transcatheter closure of persistent foramen ovale (PFO) with a Helex occluder. There was evidence of persistent left‐to‐right atrial shunt shown by transesophageal contrast echocardiography and the patient was admitted to our institution for interventional closure of the supposed residual defect. However, the PFO was completely closed by the device and left pulmonary artery injections showed a pulmonary arteriovenous fistula in the left lower lobe. This rare malformation may well explain the recurrent paradoxical embolism. Transcatheter fistula closure with coils was performed successfully. This case underlines that the existence of an isolated pulmonary arteriovenous fistula as a right‐to‐left shunt in patients with cryptogenic stroke should not be overlooked, even if a PFO is present and pulmonary arteriovenous fistula is not suggested by the initial physical findings or chest X‐ray. Catheter Cardiovasc Interv 2005;64:348–351.