Carin van Doorn

Biventricular Response After Pulmonary Valve Replacement for Right Ventricular Outflow Tract Dysfunction Is Age a Predictor of Outcome

Background— The timing of pulmonary valve replacement (PVR) for free pulmonary incompetence in patients with congenital heart disease remains a dilemma for clinicians. We wanted to assess the determinants of improvement after PVR for pulmonary regurgitation over a wide range of patient ages and to use any identified predictors to compare clinical outcomes between patient groups. Methods and Results— Seventy-one patients (mean age 22±11 years; range, 8.5 to 64.9; 72% tetralogy of Fallot) underwent PVR for severe pulmonary regurgitation. New York Heart Association class improved after PVR (median of 2 to 1, P<0.0001). MRI and cardiopulmonary exercise testing were performed before and 1 year after intervention. After PVR, there was a significant reduction in right ventricular volumes (end diastolic volume 142±43 to 91±18, end systolic volume 73±33 to 43±14 mL/m2, P<0.0001), whereas left ventricular end diastolic volume increased (66±12 to 73±13 mL/m2, P<0.0001). Effective cardiac output significantly increased (right ventricular: 3.0±0.8 to 3.3±0.8 L/min, P=0.013 and left ventricular: 3.0±0.6 to 3.4±0.7 L/min, P<0.0001). On cardiopulmonary exercise testing, ventilatory response to carbon dioxide production at anaerobic threshold improved from 35.9±5.8 to 34.1±6.2 (P=0.008). Normalization of ventilatory response to carbon dioxide production was most likely to occur when PVR was performed at an age younger than 17.5 years (P=0.013). Conclusions— A relatively aggressive PVR policy (end diastolic volume <150 mL/m2) leads to normalization of right ventricular volumes, improvement in biventricular function, and submaximal exercise capacity. Normalization of ventilatory response to carbon dioxide production is most likely to occur when surgery is performed at an age ≤17.5 years. This is also associated with a better left ventricular filling and systolic function after surgery.

Rescue surgery following percutaneous pulmonary valve implantation

OBJECTIVE Percutaneous pulmonary valve insertion (PPVI) is an evolving alternative to surgical pulmonary valve insertion. The aim of this study is to review the acute complications of PPVI requiring emergency rescue surgery. PATIENTS AND METHODS Between 09/2000 and 01/2007, 152 patients (pts), received a PPVI. Patients charts were reviewed in retrospect. RESULTS Emergency rescue surgery (ERS) took place in 6 pts (3.9%). Indications for ERS were: homograft rupture two pts, dislodgment of the stented valve in a dilated right ventricular outflow tract two pts, occlusion of the right pulmonary artery one pt and compression of the left main coronary artery one pt. Cardiopulmonary bypass was established through repeat sternotomy incision with femorofemoral cannulation in 2/6 pts. The stented valve was removed in five and replaced with a homograft in three and a valved conduit in two pts. One ruptured homograft was repaired leaving the stented valve in situ. All patients survived, one sustained mild neurological impairment. CONCLUSION Although some of the acute complications of PPVI were probably related to a learning curve (4 among the first 50 pts and 2 among the last 102 patients) the need for ERS is unlikely to be completely abolished. This experience highlights the importance of close collaboration between cardiologists and surgeons in these evolving technologies. Highly skilled and responsive surgical back up is necessary to support the introduction and to sustain institutional programmes such as PPVI.

Current approaches to pulmonary regurgitation

OBJECTIVE To evaluate the effects on ventricular function and volumes following right ventricular outflow tract reconstruction (RVOTR) with pulmonary homograft replacement (PVR) and percutaneous pulmonary valve implantation (PPVI) for predominant pulmonary regurgitation. This study was not intended to compare the two approaches. METHODS We prospectively examined 25 patients (mean age 21+/-13 years, 96% tetralogy of Fallot, 1/25 with conduit dysfunction) who had PVR with RVOTR for severe pulmonary regurgitation (PR), and 11 patients (mean age 20+/-9 years, 64% tetralogy of Fallot, 9/11 with conduit dysfunction) who underwent PPVI for predominant PR. Mean age at primary repair in both groups was 4.3+/-6.6 years. Magnetic resonance imaging was performed prior to, and 1 year following, interventions. RESULTS Before procedure, NYHA classification was similar in both groups 2.1+/-0.5. Following interventions, there was a significant reduction in RV volumes in both groups. In the surgical (PVR) group, RV end-diastolic volume (EDV) decreased from 151+/-49 to 97+/-32 ml/m(2) (p<0.0001) whereas end-systolic volume (ESV) decreased from 80+/-43 to 46+/-23 ml/m(2) (p<0.0001). In the PPVI group, RV EDV decreased from 106+/-27 to 89+/-25 ml/m(2) (p=0.002) and RV ESV from 49+/-20 to 40+/-16 ml/m(2) (p=0.034). Both groups had a significant improvement in RV (63+/-20 to 72+/-16 ml/beat, p=0.003 (PVR group), 53+/-14 to 67+/-16 ml/beat, p=0.030 (PPVI group)) and LV effective stroke volume (61+/-18 to 73+/-16 ml/beat, p=0.001 (PVR group); 59+/-24 to 75+/-16 ml/beat, p=0.009 (PPVI group)). CONCLUSIONS Following either PVR with RVOTR or PPVI, there was a significant reduction in RV volumes and an improvement in RV function. Importantly, in both groups, LV effective SV increased, and this may be the parameter to judge the benefit of the procedure. These results also support PPVI as an extra dimension in complex RVOT management.

The development of a new measure of quality of life for children with congenital cardiac disease.

The purpose of the study was to develop a questionnaire measuring health-related R1 quality of life for children and adolescents with congenital heart disease, the ConQol, that would have both clinical and research applications. We describe here the process of construction of a questionnaire, the piloting and the development of a weighted scoring system, and data on the psychometric performance of the measure in a sample of 640 children and young people recruited via 6 regional centres for paediatric cardiology from across the United Kingdom. The ConQol has two versions, one designed for children aged from 8 to 11 years, and the other for young people aged from 12 to 16 years. Initial findings suggest that it is a valid and reliable instrument, is acceptable to respondents, and is simple to administer in both a research and clinical context.

Mechanical bridging to orthotopic heart transplantation in children weighing less than 10 kg: feasibility and limitations

OBJECTIVE Infants and young children are considered the most difficult group to bridge to orthotopic heart transplantation (OHT) and data regarding outcomes are scarce. METHODS We reviewed our patients ≤ 10 kg with those who were bridged to OHT using ventricular assist device (VAD) Berlin Heart (BH) Excor ± extracorporeal membrane oxygenation (ECMO) between 2004 and 2009. RESULTS Eleven children ≤ 10 kg with end-stage heart failure (cardiomyopathy or myocarditis) were treated with VAD as bridge to OHT: the median weight was 8.0 (range 3.9-10.0 kg)kg and median age was 12.3 (range 1.2-33.9 months) months. Five (45%) required ECMO support pre-BH and six were on mechanical ventilation and inotropes. In 9/11 (82%), the support mode was left ventricular assist device (L-VAD) (all alive): one of two patients needing Bi-VAD support died. On BH, the median support time was 27 days and time to extubation was 8 days. Two out of 11 (18%) suffered strokes confirmed on brain imaging; both recovered and one underwent resection of infarcted small bowel. Ten out of 11 (91%) were transplanted, one remains in hospital and nine are at home in good health. When compared to patients >10 kg bridged with BH (n = 15), the mortality (p = 0.51) and rates of neurological complications (p = 0.54) were similar. Post-transplant recovery (ventilation times and time to home discharge) was similar between the bridged children ≤ 10 kg and non-bridged children ≤ 10 kg who underwent OHT. CONCLUSIONS Mechanical bridging to transplantation is clinically feasible in children ≤ 10 kg, achieving excellent outcomes. Judicious use of VADs in smaller children will optimise the use of donor organs; however, the effect on overall OHT waiting times, if mechanical bridging was extended to a large number of small children, is unknown.

Subcutaneous low molecular weight heparin for management of anticoagulation in infants on excor ventricular assist device.

Anticoagulation in infants and children on a ventricular assist device presents particular challenges. Unfractionated heparin has poor bioavailability; it can be difficult to achieve a stable anticoagulant effect; and, in the long-term, there is a risk of osteopenia. Long-term warfarin can be difficult to manage in infants on formula milk with vitamin K supplementation. We review our recent experience with subcutaneous low molecular weight heparin. Two patients received a left ventricular assist device (Excor, Berlin Heart AG) as a bridge to transplantation. Initial anticoagulation consisted of unfractionated heparin infusion beginning 6 hours after implantation to maintain an activated partial thromboplastin time of 70 seconds, checked every 4 to 6 hours. Platelet count (aim >80,000/&mgr;l) and thromboelastography were assessed daily. Antithrombin required substitution to maintain levels >70 IU/dl. To optimize anticoagulation, both infants were switched to subcutaneous low molecular weight heparin twice daily aiming for an anti-Xa activity between 0.5 and 1.0 IU/ml. Aspirin was added on day 4, checking platelet aggregation every 2 to 4 days, aiming at arachidonic acid stimulated aggregation 10% to 30% of baseline, collagen 100% of baseline. Dipyridamole was added once stability was reached if platelets count exceeded 150,000/&mgr;l. There were no clinical thromboembolic or bleeding events. Both patients had successful transplantation.