The dilemma of subaortic stenosis--a single center experience of 15 years with a review of the literature.

OBJECTIVE: The term "subaortic stenosis" includes a variety of obstructions of the left ventricular outflow tract (LVOT), ranging from a short (discrete) subvalvular membrane to long, tunnel-like narrowing. An association with other congenital lesions is frequent. We reviewed the reported literature and describe our results, analyzing the nomenclature of and risk factors for restenosis after surgical treatment. METHODS: From 1994 to 2009, 81 children (53 males, 28 females; median age: 57 months, range [ R]: 5-204) underwent surgical relief of a subaortic stenosis. Patients were divided, according to pathology, into short segment (group A, n = 42) and complex obstructions (group B, n = 39), with the latter including long segment stenosis and/or associated anomalies such as aortic coarctation, interrupted aortic arch or Shone's complex. RESULTS: Surgery resulted in a significant reduction of the gradient between the left ventricle and the aorta in both groups (Δ P group A: 51 ± 28 mmHg, group B: 46 ± 25 mmHg). There was no operative mortality. One patient died in the early postoperative period due to pericardial tamponade. Median follow-up was 90 months (R = 0.5-187). Twenty-five (31%) patients required reoperation because of recurrent stenosis after a median of 43 months (R = 0.5-128). Seven (16%) patients belonging to group A developed restenosis, and 18 (46%) in group B. Freedom from reoperation for all patients was 60% after 10 years. 10 (40%) of the patients of group B were ultimately treated with a Ross-Konno reconstruction of the LVOT. CONCLUSION: Despite adequate surgical resection, recurrence of subaortic stenosis within several years after initial surgical treatment is frequent, especially in patients with complex lesions. In cases requiring reoperation, the surgical therapy is often extensive, and even includes Ross-Konno reconstruction of the LVOT.

The fate of the pulmonary autograft in the aortic position: experience and results of 98 patients in twelve years.

OBJECTIVE: The ideal prosthesis for aortic valve replacement in infants and adolescents is still controversially discussed. Implantation of mechanical prostheses or homografts is associated with serious risks such as reoperations, thromboembolic events and infections. This has led many surgeons to prefer the Ross operation. METHODS: Between 1996 and 2008 we performed Ross operations in 98 children and infants with a mean age of 11 years (range 1 mo-25 y), including concomitant procedures (n = 33). The operation was performed as a full-root replacement in 97 and as a subcoronary implantation in one patient. The patients were followed for up to twelve years (follow-up complete) to determine clinical and echocardiographic parameters. Mean duration of follow-up was 60 +/- 37 (range 3-150 months). RESULTS: Overall survival was 98 % (n = 96). In 70 patients (71.4 %) no autograft insufficiency (AI) could be observed. AI grade I was present in 22 patients (22.4 %), AI grade II in 3 patients (3 %), and AI grade III in one patient. The autograft in the latter patient was replaced by a mechanical prosthesis. Aortic root dilatation was observed in 10 patients (10.2 %). Z-score (median) in these patients was 4.1 (normal z-score < or = 2.4). One patient with aortic root dilatation was reoperated. A pacemaker was implanted in two patients. No patient is on constant anticoagulants. CONCLUSION: The anatomy and physiology of the LVOT is best restored by the implantation of a pulmonary autograft. This additionally provides a growth potential for infants at low risk for reoperations. Autograft dilatation is a risk that requires constant evaluation.

[Effect of noninvasive ventilation on work of breathing in obesity]. / Der Einfluss der nichtinvasiven Beatmung auf die Atemarbeit bei Adipösen.

BACKGROUND: Noninvasive ventilation with nose- or face-masks has been increasingly used in the past. The objective of mechanical ventilation is in addition to improve gas exchange to reduce breathing work. While improvement on breathing work has been shown mainly on normal-weight patients with different respiratory diseases, there is no existing data about the effect of noninvasive ventilation on the breathing work of patients with massive obesity. PATIENTS AND METHODS: Assisted mask-ventilation with bilevel positive airway pressure (BiPAP) was carried out on 5 overweight control subjects (overweight controls), 7 overweight patients with obstructive sleep apnea (OSA), 6 patients with obesitas-hypoventilation syndrome (OHS), and 7 overweight patients with chronic obstructive lung disease (COLD). Inspiratory pressure assist (IPAP) was set to 12 or 16 cm H2O, exspiratory pressure (EPAP) was set to 5 cm H2O. All, subjects were massive overweight (body mass index [BMI] 42.2 +/- 5.8; range 31.8 to 55.4 kg/m2). Respiratory muscle activity was measured as esophageal pressure change (delta Pes) and transdiaphragmatic pressure change (delta Pdi) and calculated as pressure time integral. RESULTS: With noninvasive ventilation respiratory muscle activity was significantly (p < 0.05) reduced in all groups at least 40% compared to baseline values during spontaneous respiration. CONCLUSIONS: Noninvasive ventilation via face masks can efficiently reduce work of breathing in subjects with massive obesity.

Influence of noninvasive positive pressure ventilation on inspiratory muscle activity in obese subjects.

Noninvasive positive pressure ventilation (NPPV) can improve ventilation in obese subjects during the postoperative period after abdominal surgery. Compared to nasal continuous positive airway pressure (nCPAP), NPPV was superior in correcting blood gas abnormalities both during the night-time and during the daytime in a subgroup of patients with the obesity hypoventilation syndrome (OHS). However, as it is unknown, if and to what extent NPPV can unload the respiratory muscles in the face of the increased impedance of the respiratory system in obesity, this is what was investigated. Eighteen obese subjects with a body mass index > or = 40 kg x m(-2) were investigated during the daytime, which included five healthy controls (simple obesity (SO)), seven patients with obstructive sleep apnoea (OSA) and six patients with the obesity hypoventilation syndrome (OHS). Assisted PPV was performed with bi-level positive airway pressure (BiPAP), applied via a face mask. Inspiratory positive airway pressure (IPAP) was set to 1.2 or 1.6 kPa and expiratory positive airway pressure (EPAP) was set to 0.5 kPa. Inspiratory muscle activity was measured as diaphragmatic pressure time product (PTPdi). Comparison of spontaneous breathing with BiPAP ventilation showed no significant difference in breathing pattern, although there was a tendency towards an increase in tidal volume (VT) in all three groups and a decrease in respiratory frequency (fR) in patients with OSA and OHS. End-tidal carbon dioxide (PET,CO2) with BiPAP was unchanged in SO and OSA, but was decreased in OHS. In contrast, inspiratory muscle activity was reduced by at least 40% in each group. This was indicated by a decrease in PTPdi with BiPAP 1.2/0.5 kPa from mean+/-SD 39+/-5 to 20+/-9 kPa x s (p<0.05) in SO, from 42+/-7 to 21+/-8 kPa x s (p<0.05) in OSA, and from 64+/-20 to 38+/-17 kPa x s (p<0.05) in OHS. With BiPAP 1.6/0.5 kPa, PTPdi was further reduced to 17+/-6 kPa x s in SO, and to 17+/-6 kPa x s in OSA, but not in OHS (40+/-22 kPa x s). We conclude that noninvasive assisted ventilation unloads the inspiratory muscles in patients with gross obesity.