Didier De Cannière

Robotic-enhanced biventricular resynchronization: An alternative to endovenous cardiac resynchronization therapy in chronic heart failure

BACKGROUND Cardiac resynchronization therapy (CRT) by pacing the left and right ventricles is an emerging option for treatment of severe heart failure with ventricular conduction disturbances. Stimulation through a coronary vein is currently the technique of choice to achieve left ventricular (LV) pacing. Unfortunately, this approach carries significant limitations and drawbacks. Therefore we explored robotic-enhanced thoracoscopic implantation of an epicardial lead as an alternative technique to stimulate the LV in cardiac resynchronization therapy. METHODS A total of 15 patients were included in this study. Right (atrial and ventricular) leads were implanted classically through the left subclavian vein. Robotic-enhanced thoracoscopy was then performed to implant the LV epicardial lead. RESULTS Of the 15 patients, 13 underwent successful endoscopic robotic cardiac resynchronization therapy. Two patients underwent conversion to a small thoracotomy. No perioperative complication occurred in the patients who did not undergo conversion. Acute and chronic LV lead thresholds were satisfactory in all patients, improving over time. All were subjectively and objectively improved at 4 months. As compared with conventional methods, the procedural cost was not significantly affected. CONCLUSIONS Based on this feasibility study, we believe that robotic LV epicardial lead implantation is a valuable option to achieve biventricular resynchronization therapy. It allows for more reproducible acute thresholds for LV pacing and sensing than does the percutaneous approach; enables fine tuning of the LV lead position, thus potentially providing optimal hemodynamic benefit; and avoids the pitfalls and limitations of the endovenous approach. Therefore it deserves further prospective studies to assess its place in the therapeutic armamentarium against heart failure.

Effects of Valve Replacement for Aortic Stenosis on Mitral Regurgitation

We aimed to prospectively and quantitatively assess the effects of aortic valve replacement (AVR) for aortic stenosis (AS) on mitral regurgitation (MR) and to examine the determinants of the changes in MR. Fifty-two patients with AS scheduled for AVR were included if holosystolic MR not being considered for replacement or repair was detected. MR was quantified using the proximal isovelocity surface area method before and 8 +/- 4 days after surgery. Mitral valvular deformation parameters did not change significantly, but the mitral effective regurgitant orifice (ERO) and regurgitant volume decreased from 11 +/- 6 mm(2) to 8 +/- 6 mm(2) and from 20 +/- 10 ml to 11 +/- 9 ml, respectively (both p <0.0001). Using multiple linear regression analysis, preoperative severity of MR, mitral leaflet coaptation height, and end-diastolic volume decrease were independently associated with postoperative reduction in MR, whereas changes in mitral valve morphology after surgery were not. MR etiology did not predict the reduction in MR. In conclusion, the decrease in MR observed in most patients after AVR is associated with the magnitude of acute left ventricular reverse remodeling. As the reduction in left ventricular systolic pressure contributes to the decrease in regurgitant volume, the preoperative quantitative assessment of MR should best be performed by measurement of the ERO.

Left ventricular outflow tract obstruction after mitral valve replacement

We describe a patient with left ventricular outflow tract obstruction after mitral valve replacement preserving the anterior subvalvular apparatus. Postoperative transesophageal echocardiography demonstrated systolic narrowing of the left ventricular outflow tract by a bulging septum and systolic anterior motion of the preserved anterior mitral leaflet. Septal myectomy and transaortic mitral apparatus resection enabled us to relieve the left ventricular outflow tract obstruction. This suggests that septal hypertrophy might be a relative contraindication to the preservation of the anterior mitral subvalvular apparatus in mitral replacement.

Systemic vascular effects of isoflurane versus propofol anesthesia in dogs

Vascular effects of general anesthesia are usually described by changes in vascular resistance, which assumes a linear pressure-flow relationship passing through the zero-flow zero-pressure point, and neglects the pulsatile properties of the circulation. We compared the systemic vascular effects of isoflurane versus propofol anesthesia by measurements of aortic pressure-flow relationships, systemic vascular impedance (SVZ), and pressure transfer function (PTF). Eight mechanically ventilated dogs received isoflurane 1.4% end-tidal and propofol 18 mg [centered dot] kg-1 [centered dot] h-1 in a random sequence. During both periods, pressure-flow data and SVZ data were obtained at baseline and after stepwise reduction of the cardiac output by inflation of a balloon in the inferior vena cava. Instantaneous pressure and flow were measured at the aortic root using a micromanometer-tipped catheter and an ultrasonic flow probe. Compared to baseline, low flow decreased the aortic pressure and increased the resistance, characteristic impedance, and oscillatory/total work ratio. Compared with isoflurane, propofol resulted in higher aortic pressure, lower characteristic impedance, and lower oscillatory/total work ratio. Low-frequency PTF moduli decreased at low flow and increased with propofol. We conclude that, compared with isoflurane, propofol better preserves aortic pressure and increases aortic compliance, and thus improves the energy transmission from the left ventricle to the arterial system. (Anesth Analg 1996;83:958-64)

Assessment based on EuroSCORE of ministernotomy for aortic valve replacement.

To assess the advantages of a ministernotomy over a standard sternotomy for aortic valve replacement, 191 patients were classified as low-, medium-, and high-risk by EuroSCORE. A ministernotomy was carried out in 100 patients, and a standard sternotomy was used in 91. Among low-risk patients, those who had a ministernotomy showed a marginal increase in atrial fibrillation. Of the medium-risk patients, those who had a sternotomy had significantly more atrial fibrillation and slightly more general infections. In the high-risk subgroup, significantly more atrial fibrillation was observed in the sternotomy group, and more neurologic events were observed in the ministernotomy group; the difference became nonsignificant when only severe events were considered. There was a significant benefit in terms of rhythm disturbances in medium- and high-risk patients who underwent a ministernotomy compared to those who had a full sternotomy. Mortality, duration of intensive care, and hospital stay were not influenced by the operative method.

Oxidative stress produced by circulating microparticles in on-pump but not in off-pump coronary surgery.

Objective — This study was undertaken to assess whether plasmas isolated during off-pump coronary surgery trigger less oxidative stress than those isolated during on-pump surgery. Methods and results — Plasmas were sampled from patients before (T0), just after (T1) and 24 hours after (T2) cardiac surgery (n = 24 on-pump and n = 10 off-pump). Rings of rat thoracic aortas were incubated for 20 hours with these different plasmas (100 μl + 4 ml medium) or saline (control). Thereafter, superoxide anion production was assessed by chemiluminescence and the mean signal was expressed as percent of that in the control ring. In rat aorta exposed to plasmas from on-pump CABG patients (n = 6), the signal was enhanced by 210 ± 29% at T1 (P < 0.05) and by 174 ± 29% at T2 (P < 0.05) versus 53 ± 12% at T0. Moreover, at T1 and T2, there was an upregulation of p22phox , the key subunit of NADPH oxidase, the main enzyme involved in oxidative stress of the vascular wall. In contrast, off-pump plasmas did not induce this superoxide production. Incubation with microparticles obtained by ultracentrifugation also markedly enhanced the signal at T1 and T2 (vs. T0) in the on-pump group (but not in the off-pump group). Selective removal of CD34, CD105, CD59, CD146, CD42 microparticles using flow cytometry did not abolish the signal. CRP and SAA plasma levels were enhanced only at T2 in both groups. Conclusions — Plasmas isolated after on-pump but not off-pump coronary bypass surgery can induce superoxide generation by the vascular wall which seems related to circulating microparticles remaining present at least 24 hours after the procedure that might be of endothelial origin.

Pulmonary vein isolation by robotic-enhanced thoracoscopy for symptomatic paroxysmal atrial fibrillation.

BACKGROUND Pulmonary vein isolation (PVI) has been shown to be effective treatment of patients with symptomatic paroxysmal atrial fibrillation (PAF). The percutaneous approach is currently the technique of choice. Unfortunately, this procedure has limitations and complications that lead to fluctuating success rates. We explored an alternative technique of robotic-enhanced, closed-chest PVI with an endoscopic microwave-based catheter. METHODS Seven symptomatic PAF patients were included in the study. The pulmonary veins were isolated through right (only) robotic-enhanced thoracoscopy on the beating heart. RESULTS Six patients underwent successful endoscopic PVI. In 1 patient the operation was converted into small right thoracotomy. Operative assessment of the ablation line showed a successful electric block in every patient. Three months after the procedure, the first 5 patients were in permanent sinus rhythm. The 2 other patients had AF but had less frequent and less symptomatic episodes compared with the preoperative situation. CONCLUSIONS On the basis of this preliminary experience, we believe that in the near future endoscopic right-chest robotic-enhanced PVI on the beating heart may become a valid option in the treatment of symptomatic PAF patients. This procedure allows for more-reproducible ablation lines and may avoid many of the pitfalls and drawbacks of the percutaneous approach. Therefore this technique deserves larger prospective evaluation in the treatment of AF.

Comparison of the hemodynamic responses to molsidomine and isosorbide dinitrate in congestive heart failure

To evaluate the mechanisms involved in nitrate tolerance, we randomized 23 patients with congestive heart failure resulting from coronary artery disease to an isosorbide dinitrate or a molsidomine infusion. The drugs were titrated to decrease pulmonary capillary wedge pressure by > or = 30% or > or = 10 mm Hg. Then isosorbide dinitrate, molsidomine, or placebo was infused in a double-blind randomized manner for 24 hours. In all patients, treatment with enalapril was begun > or = 48 hours before the beginning of the protocol and was continued throughout the study to avoid renin-angiotensin activation. The pulmonary capillary wedge pressure remained significantly decreased at 24 hours during molsidomine infusion only. No significant increase in catecholamines occurred. Because molsidomine differs from organic nitrates by its property of directly stimulating guanylate cyclase without depending on thiol group availability, these results suggest that impaired biotransformation of nitrates is involved in tolerance induced by high doses of isosorbide dinitrate in congestive heart failure.

Cardiac calcified amorphous tumor: A systematic review of the literature

Background Calcified amorphous tumor (CAT) of the heart is a rare non-neoplastic intracavitary cardiac mass. Several case reports have been published but large series are lacking. Objective To determine clinical features, current management and outcomes of this rare disease. Design A systematic review of all articles reporting cases of CAT in order to perform a pooled analysis of its clinical features, management and outcomes. Data sources An electronic search of all English articles using PUBMED was performed. Further studies were identified by cross-referencing from relevant papers. Inclusion criteria We restricted inclusion to articles reporting cases of CAT in the English language literature published up to July 2014. Data extraction One author performed data extraction using predefined data fields. Results A total of 27 articles, reporting 42 cases of CAT were found and included in this review. Conclusion In this review, the most frequent presenting symptoms were dyspnea and embolic events. Mitral valve and annulus were the most frequent location of CAT. Surgery was most of the time required to confirm diagnosis, and was relatively safe. Overall outcome after surgical resection was good.

The clinical challenge of concomitant aortic and mitral valve stenosis.

The coexistence of mitral and aortic stenosis is not exceptional. Whereas rheumatic fever is currently plummeting in the Western countries, the incidence of degenerative disease is inversely increasing. The haemodynamic interactions which may interfere both with the usual echocardiographic parameters and with the invasive assessment may render the diagnosis difficult. The therapeutic challenges raised by this entity should not be underestimated. The increased morbidity and mortality of multivalvular surgery has to be balanced with the risk of a second operation down the line if one valvular involvement, deemed of a lesser importance, is neglected. This complex situation requires the multidisciplinary approach of a heart team involving surgeons, cardiologists, geriatrists if need be and imaging specialists.