Hemodynamic Changes following Aortic Valve Bypass: A Mathematical Approach

Aortic valve bypass (AVB) has been shown to be a viable solution for patients with severe aortic stenosis (AS). Under this circumstance, the left ventricle (LV) has a double outlet. The objective was to develop a mathematical model capable of evaluating the hemodynamic performance following the AVB surgery. A mathematical model that captures the interaction between LV, AS, arterial system, and AVB was developed. This model uses a limited number of parameters that all can be non-invasively measured using patient data. The model was validated using in vivo data from the literature. The model was used to determine the effect of different AVB and AS configurations on flow proportion and pressure of the aortic valve and the AVB. Results showed that the AVB leads to a significant reduction in transvalvular pressure gradient. The percentage of flow through the AVB can range from 55.47% to 69.43% following AVB with a severe AS. LV stroke work was also significantly reduced following the AVB surgery and reached a value of around 1.2 J for several AS severities. Findings of this study suggest: 1) the AVB leads to a significant reduction in transvalvular pressure gradients; 2) flow distribution between the AS and the AVB is significantly affected by the conduit valve size; 3) the AVB leads to a significant reduction in LV stroke work; and 4) hemodynamic performance variations can be estimated using the model.Fonds quebecois de la recherche sur la nature et les technologies (176048

0304: How long should we keep a temporary pace maker after transcatheter aortic valve replacement (TAVR)

A temporary pace-maker (TPM) is often used after TAVR due to the risk of atrioventricular block (AVB) in the following days, related to progressive conduction system injuries. However guidelines are unclear as when to safely remove it. Between 2013 and 2014, 195 patients without previous permanent pacemaker, were prospectively followed after TAVR (69 Edwards Sapiens (ES) and 126 CoreValve (CV)). 47 had preoperative bundle branch block, 23 left (LBBB), 24 right sided (RBBB). Peri-operative high degree AVB was noted in 37 patients (20%). 24 were transient, less than 10mn and; 13 persisted at the end of the procedure and were implanted with a permanent pace-maker. New LBBB was observed in 55 patients (28%). In the post-operative period, 23 patients (13%) developped AVB (20 patients within 5 days, and 3 patients after 7 days) (4 ES and 19 CV). No new AV block had occurred at one month in the remaining population. Risk factors for late AVB were peri-operative transient AVB (40%), post-operative RBBB (30%), or LBBB (20%); preexistent RBBB and Corevalve model. Conversely 41 of the 42 patients without AVB or bundle branch block did not need temporary pacing in the post operative time. The only patient without any perioperative event who developed a late AV block at day 7 had a CV inserted in an old surgical valve. However, sinus dysfunction occurred in 2 patients treated with amiodarone for atrial fibrillation in the post operative period, needing temporary pacing. Conclusion: The use of TPM after TAVR is common for the management of delayed high degree AVB. The main risk factors are peri-operative AVB and post-operative BBB. Most of delayed AVB occur within 5 days. Later AVB preceded by prolonged PR interval and BBB should increase the length of TPM. However, in the absence of these factors TPM could be shortened.Abstract 0304 – Figure: Time occurence of AVB (CV=Corevalve, ES=Sapien

Atrioventricular block of intraoperative device closure perimembranous ventricular septal defects; a serious complication

<p>Abstract</p> <p>Background</p> <p>Atrioventricular block (AVB) is a well-reported complication after closure of perimembranous ventricular septal defects (VSDs). To report the occurrence of AVB either during or following closure of perimembranous VSDs using a novel "hybrid" method involving a minimal inferior median incision and of intraoperative device closure of the perimembranous VSDs.</p> <p>Methods</p> <p>Between January 2009 and January 2011, patients diagnosed with perimembranous VSDs eligible for intraoperative device closure with a domestic occluder were identified. All patients were assessed by real-time transesophageal echocardiography (TEE) and electrocardiography.</p> <p>Results</p> <p>Of the 97 included patients, 94 were successfully occluded using this approach. Complete AVB occurred in only one case and one case of Mobitz type II AVB was diagnosed intraoperatively. In both patients, the procedure was aborted and the AVBs quickly resolved. Glucocorticosteroids were administered to another two patients who developed Mobitz type II AVB intraoperatively. Those two patients converted to Mobitz type I AVB 3 days and 5 days postsurgically. During the follow-up period (range, 6-24 months), one patient developed complete AVB 1 week following device insertion. Surgical device removal was followed by a rapid and complete recovery of atrioventricular conduction.</p> <p>Conclusions</p> <p>Intraoperative device closure of perimembranous VSDs with a domestic occluder resulted in excellent closure rates; however, AVB is a serious complication that can occur either during or any time after device closure of perimembranous VSDs. The technique described herein may reduce the incidence of perioperative AVB complications. Surgeons are encouraged to closely monitor all patients postsurgically to ensure AVB does not occur in their patients. Additional long-term data to better identify the prevalence and risk factors for AVB in treated patients are needed.</p

Impact of audiovisual biofeedback on interfraction respiratory motion reproducibility in liver cancer stereotactic body radiotherapy.

INTRODUCTION: Irregular breathing motion exacerbates uncertainties throughout a course of radiation therapy. Breathing guidance has demonstrated to improve breathing motion consistency. This was the first clinical implementation of audiovisual biofeedback (AVB) breathing guidance over a course of liver stereotactic body radiotherapy (SBRT) investigating interfraction reproducibility. METHODS: Five liver cancer patients underwent a screening procedure prior to CT sim during which patients underwent breathing conditions (i) AVB, or (ii) free breathing (FB). Whichever breathing condition was more regular was utilised for the patient's subsequent course of SBRT. Respiratory motion was obtained from the Varian respiratory position monitoring (RPM) system (Varian Medical Systems). Breathing motion reproducibility was assessed by the variance of displacement across 10 phase-based respiratory bins over each patient's course of SBRT. RESULTS: The screening procedure yielded the decision to utilise AVB for three patients and FB for two patients. Over the course of SBRT, AVB significantly improved the relative interfraction motion by 32%, from 22% displacement difference for FB patients to 15% difference for AVB patients. Further to this, AVB facilitated sub-millimetre interfraction reproducibility for two AVB patients. CONCLUSION: There was significantly less interfraction motion with AVB than FB. These findings demonstrate that AVB is potentially a valuable tool in ensuring reproducible interfraction motion

Diagnostic Yield of Genetic Testing in Young Patients With Atrioventricular Block of Unknown Cause

BACKGROUND: The cause of atrioventricular block (AVB) remains unknown in approximately half of young patients with the diagnosis. Although variants in several genes associated with cardiac conduction diseases have been identified, the contribution of genetic variants in younger patients with AVB is unknown. METHODS AND RESULTS: Using the Danish Pacemaker and Implantable Cardioverter Defibrillator (ICD) Registry, we identified all patients younger than 50 years receiving a pacemaker because of AVB in Denmark in the period from January 1, 1996 to December 31, 2015. From medical records, we identified patients with unknown cause of AVB at time of pacemaker implantation. These patients were invited to a genetic screening using a panel of 102 genes associated with inherited cardiac diseases. We identified 471 living patients with AVB of unknown cause, of whom 226 (48%) accepted participation. Median age at the time of pacemaker implantation was 39 years (interquartile range, 32–45 years), and 123 (54%) were men. We found pathogenic or likely pathogenic variants in genes associated with or possibly associated with AVB in 12 patients (5%). Most variants were found in the LMNA gene (n=5). LMNA variant carriers all had a family history of either AVB and/or sudden cardiac death. CONCLUSIONS: In young patients with AVB of unknown cause, we found a possible genetic cause in 1 out of 20 participating patients. Variants in the LMNA gene were most common and associated with a family history of AVB and/or sudden cardiac death, suggesting that genetic testing should be a part of the diagnostic workup in these patients to stratify risk and screen family members

Self-expandable metal stents in the treatment of acute esophageal variceal bleeding

Acute variceal bleeding (AVB) is a life-threatening complication in patients with cirrhosis. Hemostatic therapy of AVB includes early administration of vasoactive drugs that should be combined with endoscopic therapy, preferably banding ligation. However, failure to control bleeding or early rebleed within 5 days still occurs in 15-20% of patients with AVB. In these cases, a second endoscopic therapy may be attempted (mild bleeding in a hemodynamically stable patient) or we can use a balloon tamponade as a bridge to definitive derivative treatment (i.e., a transjugular intrahepatic portosystemic shunt). Esophageal balloon tamponade provides initial control in up to 80% of AVB, but it carries a high risk of major complications, especially in cases of long duration of tamponade (>24 h) and when tubes are inserted by inexperienced staff. Preliminary reports suggest that self-expandable covered esophageal metallic stents effectively control refractory AVB (i.e., ongoing bleeding despite pharmacological and endoscopic therapy or massive bleeding precluding endoscopic therapy) with a low incidence of complications. Thus, covered self-expanding metal stents may represent an alternative to the Sengstaken-Blakemore balloon for the temporary control of bleeding in treatment failures. Further studies are required to determine the role of this new device in AVB

Improved Survival with the Patients with Variceal Bleed

Variceal hemorrhage is a major cause of death in patients with cirrhosis. Over the past two decades new treatment modalities have been introduced in the management of acute variceal bleeding (AVB) and several recent studies have suggested that the outcome of patients with cirrhosis and AVB has improved. Improved supportive measures, combination therapy which include early use of portal pressure reducing drugs with low rates of adverse effects (somatostatin, octerotide or terlipressin) and endoscopic variceal ligation has become the first line treatment in the management of AVB. Short-term antibiotic prophylaxis, early use of lactulose for prevention of hepatic encephalopathy, application of early transjugular intrahepatic portasystemic shunts (TIPS), fully covered self-expandable metallic stent in patients for AVB may be useful in those cases where balloon tamponade is considered. Early and wide availability of liver transplantation has changed the armamentarium of the clinician for patients with AVB. High hepatic venous pressure gradient (HVPG) >20 mmHg in AVB has become a useful predictor of outcomes and more aggressive therapies with early TIPS based on HVPG measurement may be the treatment of choice to reduce mortality further

0049: Long-term follow- up of AV conduction disturbances after slow pathway ablation in patients with AV node reentrant tachycardia

AV block following radiofrequency (RF) ablation for the treatment of atrioventricular nodal reentrant tachycardia (AVNRT) is a rare but well recognised complication of the procedure. The purpose of the study was to report the long-term follow-up of patients a first d (AVB1), second d (AVB2), or third d A V block (AVB3) occurred during ablation of AVNRT.Methods930 patients, 615 females, aged from 12 to 92 years, mean age 52±18, had AVNRT. RF energy, 65°, 40 watts was delivered on the slow pathway, until AVNRT was not induced.Results94 patients presented a transitory or permanent AVB1,2,3. In 8, mean age 53±21.5 years, AVB was of vagal origin generally occurring at femoral puncture (group I). In 26 patients, mean age 46±21, it was traumatic and regressive occurring either in young patients with a normal conduction system or in 3 patients with a left bundle branch block. In remaining 60 patients, AVB was directly related to the RF application; AVB was of first degree in 22 patients aged 56±17 years; it was of 2nd or third degree AVB in 38 patients: in 2 patients AVB3 remained permanent and in all other patients it was partially or totally regressive. After a follow-up of 2.1±2 years, pacemaker implantation was implanted in 15 patients, 1 patient with traumatic AVB3 aged 81 years, 5 patients with AVB3 during ablation, 2 with permanent AVB3 (0.2%) and 3 with transitory AVB3 and 9 patients without AVB during ablation. In these last patients, 2 had spontaneous long HV interval. Age of these patients differed from age of patients with RF-related AVB (73±14 vs 56±17) (p< 0.04). 5 patients with transitory AVB3 remained symptomatic with alternating slow junctional rhythm and sinus tachycardia.ConclusionsAVB remains frequent during AVNRT ablation (10%) but it is frequently benign and not directly related to the RF application. Permanent complete AVB is exceptional (0.2%). Patients with transitory complete AVB remain at high risk of later events as conduction disturbances or sinus tachycardia. Other AVB’s are age-related and probably without relation with ablation. Permanent or transitory 1 degree AVB seems without clinical significance