Effects of Chronic Hypoxemia on Chemosensitivity in Patients With Univentricular Heart

AbstractObjectives. We sought to compare the arterial blood gas chemosensitivity in relation to exercise ventilatory response in patients with univentricular heart and cyanosis and in patients with univentricular heart and Fontan-type circulation without cyanosis.Background. Patients with univentricular heart demonstrate excessive ventilation during exercise. Chronic hypoxemia may alter chemoreceptor function, affecting ventilation.Methods. Cardiopulmonary exercise testing was performed in 10 patients with rest or stress-induced cyanosis (cyanotic group: mean age ± SE 30.5 ± 2.3 years; 5 men), 8 patients without cyanosis with Fontan-type circulation (Fontan group: mean age 29.4 ± 1.5 years; 4 men) and 10 healthy control subjects (normal group: mean age 30.7 ± 1.9 years; 5 men). Hypoxic and hypercapnic chemosensitivity were assessed by using transient inhalations of pure nitrogen and the rebreathing of 7% CO2in 93% O2, respectively.Results. Peak O2consumption was comparable in both patient groups (21.7 ± 2.5 [cyanotic group] vs. 21.0 ± 1.9 ml/kg per min [Fontan group]) but was lower than that in the normal group (34.7 ± 1.9 ml/kg per min). The ventilatory response to exercise, characterized by the regression slope relating minute ventilation to CO2output, was higher in the cyanotic group (43.4 ± 4.0) than in the Fontan group (31.4 ± 3.0, p = 0.02) and the normal group (23.1 ± 1.1). Hypoxic chemosensitivity was blunted in the cyanotic group compared with that in the Fontan and normal groups (0.148 vs. 0.448 [p = 0.02] vs. 0.311 liter/min per percent arterial O2saturation, respectively) and did not correlate with the ventilatory response to exercise (r = −0.36, p = 0.29). In contrast, hypercapnic chemosensitivity represented by the slope of the hypercapnic-ventilatory response line was similar in the cyanotic, Fontan and normal groups (1.71 vs. 1.76 vs. 1.70 liter/min per mm Hg, respectively), but the response line had shifted to the left in the cyanotic group (x intercept = 31.9 vs. 39.9 mm Hg [p = 0.026]), compared with 45.2 mm Hg in normal subjects. These findings suggest that in the cyanotic group, ventilation is greater for a given level of arterial CO2tension and thus may partly explain the increased exercise ventilatory response in this group.Conclusions. Hypoxic chemosensitivity is blunted in patients with univentricular heart and cyanosis and does not determine the exercise ventilatory response. CO2elimination appears more important. The blunting of hypoxic chemosensitivity is reversible once chronic hypoxemia is relieved, as evident in the Fontan group

316 Percutaneous right outflow tract valve implantation: when should we pre-stent?

IntroductionPercutaneous pulmonary valve insertion has been recently introduced in clinical setting. Patient selection is widely accepted. Initial results demonstrated early and differed stent fractures that make consider pre-stenting as a previous step for the procedure. To date, differed or intra-procedure pre-stenting are both accepted techniques.Patients and methodsWe reviewed patients included over the last 6 months in the prospective study (REVALV) for patients undergoing RVOT intervention for severe stenosis and/or insufficiency. Only valved stent group is analyzed here. All patients undergoing valved stent implantation are previously pre-stented with a bare metal stent according to present recommendations. Thirty-seven patients were included, distributed in two gropus according moment of pre-stenting: differed pre-stenting (bare metal stent implantation several days before valved stent implantation -20 patients-) and same procedure pre-stenting (bare metal stent implantation at the same procedure of valved stent implantation-17 patients-). For analytical purposes, we considered RVOT anatomy (homograft, synthetic tube, patch-extended RVOT or native outflow tract).ResultsOverall, no differences were found regarding mean procedure times (77,35 vs 96,88, p=NS) and time of hospitalization (2,95 vs 3,63, p=NS). Mean delay time from pre-stenting to valvulation was 196,5 + −68 days. Rv to Ao ratio improvement from basal to valvulation was significantly better in intra-procedure pre-stenting group (0,172 vs 0,373, p=0,009). Concerning complications, bare metal stent mobilization happened just after implantation while trying to place valved stent delivery gain. Two pelvic hematomas were observed (one of each group).ConclusionsIntra-procedure pre-stenting influences final result when considering RV-to-Ao ratio improvement, probably related to increase radial strength. The risk, however, remains higher as freshly implanted bare metal stent can mobilize, especially in native RVOT. Stratification of patient should be considered while choosing candidates for valved stent implantation

286 – Percutaneous right outflow tract valve implantation: substrate matters

IntroductionPercutaneous pulmonary valve insertion has been recently introduced in clinical setting. Patient selection is widely accepted. These candidates are however heterogeneous, in regard of heart defects, and type of surgical right ventricular outflow tract (RVOT) reconstruction. It is presently unclear in the literature if type of surgical reconstruction matters for the success of the pulmonary valve insertion. Our goal was to compare the hemodynamic results of percutaneous pulmonary valve in patients with homografts, prosthetic conduit or RVOT reconstructed with patch.Patients and methodsWe reviewed patients included over the last 6 months in the prospective study (REVALV) for patients undergoing RVOT intervention for severe stenosis and/or insufficiency. Only valved stent group is analyzed here. All patients undergoing valved stent implantation are previously pre-stented with a bare metal stent according to present recommendations. Thirty-seven patients were included, distributed in three groups according to type of RVOT reconstruction (homograft REVALV is a multicentric prospective study for patients undergoing RVOT intervention for severe stenosis and/or insufficiency. Patients are distributed in three groups according to type of RVOT reconstruction (homograft, n = 10; prosthetic conduit, n = 20; RVOT enlargement by patch, n = 7).ResultsOverall, all groups were similar in RV to AP gradient improvement (after pre-stenting mean 30,79 vs 28 p = NS; final result mean 23,71 vs 28,17, p = NS), RV to aorta pressures ratio (after pre-stenting 0,187 vs 0,3117 p = NS; final result man 0,315 vs 0,317, p = NS). If considering non-extensible synthetic tubes we observe that RV-to-AP improvement is significantly worst to the rest of the group (mean 7,07 vs 0,17, p = 0,005). When focusing on outflow tract diameter, results did not differ in homograft group and patch group. In contrast, diameter did play a role in those patients having a synthetic tube, with a cut-off at 20mm diameter. Below 20mm, relieve of outflow tract gradient was significantly worse than for bigger conduits.DiscussionPulmonary valve insertion is efficient in all type of RVOT reconstruction at least in the short term. The diameter of the conduits did not play a role in RVOT obstruction relief as long as surgical substrates are homografts or patch enlargement. In patients with prosthetic conduits, size matters. In non-extensible synthetic tubes results are worst. Reduced distensibility and progressive diameter reduction may lead to not consider these patients as good candidates for this procedure

275: Percutaneous insertion of a Melody valve in tricuspid position: technical aspects

Backgroundpercutaneous transcatheter heart valve replacement of aortic or pulmonary valve is established. Transcatheter atrioventricular valve replacement is been described. We report our experience focusing on the technical aspects.Methodswe retrospectively review the files of patients who received a transcatheter valve in tricuspid position between 2008 and 2012.ResultsFour patients were found. 3 had a heterograft (conduit of 14-mm, Sorin 33 et Edwards Perimount 33) and one had a connection between the RA and the RV infundibulum without a valve. Two patients had tricuspid regurgitation as a primary lesion, one had stenotic valve and the last one a mixted lesion. All successfully received a Melody valve from a femoral access. In patients with stenotic lesion, a predilatation using a high pressure balloon was performed before valve implant. In patients with regurgitation, the landing zone was calibrated using a low pressure balloon. These patients were presented to create a landing zone of adequate diameter. Melody valves were inserted using a 22-mm balloon catheter in 3 and a 24-mm in one. All but one were post-dilated. There was no significant regurgitation. The mean gradient across the tricuspid valve felt from 12 to 4.6-mmHg. One patient needed an epicardic pacemaker because of AV block following balloon dilatation. One patient required inotropic support and ventilation following the procedure but recovered after few days.ConclusionTranscatheter tricuspid valve insertion is feasible in patients with surgical hetero or homografts after a careful selection. The mechanism of dysfunction must be known. In case of stenosis or mixted lesions, the only question is to know if the stenosis could be relief. In case of regurgitation, it is very important to know the features of surgical substrats and to calibrate the tricuspid orifice. Finally, patients with inappropriate landing zone should be presented prior to valve insertion

Catheter ablation of atrial tachyarrhythmias in patients with atrioventricular septal defect

AIMS: The incidence of atrial tachyarrhythmias is high in patients with atrioventricular septal defect (AVSD). No specific data on catheter ablation have been reported so far in this population. We aimed to describe the main mechanisms of atrial tachyarrhythmias in patients with AVSD and to analyse outcomes after catheter ablation. METHODS AND RESULTS: This observational multi-centric cohort study enrolled all patients with AVSD referred for catheter ablation of an atrial tachyarrhythmia at six tertiary centres from 2004 to 2022. The mechanisms of the different tachyarrhythmias targeted were described and outcomes were analysed. Overall, 56 patients (38.1 ± 17.4 years, 55.4% females) were included. A total of 87 atrial tachyarrhythmias were targeted (mean number of 1.6 per patient). Regarding main circuits involved, a cavo-annular isthmus-dependent intra-atrial re-entrant tachycardia (IART) was observed in 41 (73.2%) patients and an IART involving the right lateral atriotomy in 10 (17.9%) patients. Other tachyarrhythmias with heterogeneous circuits were observed in 13 (23.2%) patients including 11 left-sided and 4 right-sided tachyarrhythmias. Overall, an acute success was achieved in 54 (96.4%) patients, and no complication was reported. During a mean follow-up of 2.8 ± 3.8 years, 22 (39.3%) patients had at least one recurrence. Freedom from atrial tachyarrhythmia recurrences was 77.5% at 1 year. Among 15 (26.8%) patients who underwent repeated ablation procedures, heterogeneous circuits including bi-atrial and left-sided tachyarrhythmias were more frequent. CONCLUSION: In patients with AVSD, most circuits involve the cavo-annular isthmus, but complex mechanisms are frequently encountered in patients with repeated procedures. The acute success rate is excellent, although recurrences remain common during follow-up.</p

Cor Triatriatum Sinister diagnosed in adult life with three dimensional transesophageal echocardiography

<p>Abstract</p> <p>Background</p> <p>Cor triatriatum is a very rare congenital abnormality, usually symptomatic during childhood, diagnosis in adult age is less common.</p> <p>Case Presentation</p> <p>We report the case of a 40 years old woman referred to our hospital for atrial flutter ablation, transthoracic cardiac bidimensional echocardiography showed an abnormal membrane bisecting the left atrium, the diagnosis of cor triatriatum was fully made via three dimensional transesophageal echocardiography. More interstingly three other cardiac anomalies were associated: ostium secundum atrial septal defect, dilated coronary sinus due probably to persistent left superior vena cava and normally functioning bicuspid aortic valve.</p> <p>Conclusions</p> <p>Cor triatriatum sinister in adult life is important to recognize because it may be easily surgically correctable when hemodynamically significant. Three Dimensional transesophageal echocardiography is a minimally invasive and highly sensitive diagnostic modality.</p