Jean Lambert

Lower Incidence of Thrombus Formation With Cryoenergy Versus Radiofrequency Catheter Ablation

Background—Radiofrequency (RF) catheter ablation is limited by thromboembolic complications. The objective of this study was to compare the incidence and characteristics of thrombi complicating RF and cryoenergy ablation, a novel technology for the catheter-based treatment of arrhythmias. Methods and Results—Ablation lesions (n=197) were performed in 22 mongrel dogs at right atrial, right ventricular, and left ventricular sites preselected by a randomized factorial design devised to compare RF ablation with cryocatheter configurations of varying sizes (7F and 9F), cooling rates (−1°C/s, −5°C/s, and −20°C/s) and target temperatures (−55°C and −75°C). Animals were pretreated with acetylsalicylic acid and received intraprocedural intravenous unfractionated heparin. Seven days after ablation, the incidence of thrombus formation was significantly higher with RF than with cryoablation (75.8% versus 30.1%, P =0.0005). In a multiple regression model, RF energy remained an independent predictor of thrombus formation compared with cryoenergy (OR, 5.6; 95% CI, 1.7, 18.1;P =0.0042). Thrombus volume was also significantly greater with RF than with cryoablation (median, 2.8 versus 0.0 mm3;P <0.0001). More voluminous thrombi were associated with larger RF lesions, but cryolesion dimensions were not predictive of thrombus size. Conclusions—RF energy is significantly more thrombogenic than cryoenergy, with a higher incidence of thrombus formation and larger thrombus volumes. The extent of hyperthermic tissue injury is positively correlated with thrombus bulk, whereas cryoenergy lesion size does not predict thrombus volume, most likely reflecting intact tissue ultrastructure with endothelial cell preservation.

Relation between conduit vessel stiffness (assessed by tonometry) and endothelial function (assessed by flow-mediated dilatation) in patients with and without coronary heart disease.

Endothelial dysfunction and large artery stiffness occur in patients with risk factors for coronary artery disease (CAD) and in those with established CAD. We evaluated the relation between endothelial function and conduit vessel distensibility in normal subjects, in patients with documented stable CAD, and in patients demonstrating only risk factors but no overt atherosclerosis. Endothelium-dependent dilatation was evaluated by way of flow-mediated dilatation of the brachial artery using high-resolution ultrasound. Large artery stiffness was assessed using tonometry. After adjusting for age and intergroup differences, percent flow-mediated dilatation showed statistically significant correlations with several measures of stiffness, including central pulse pressure (r = -0.457, p = 0.019), central systolic pressure (r = -0.442, p = 0.024), peripheral pulse pressure (r = -0.393, p = 0.039), peripheral systolic pressure (r = -0.398, p = 0.036), and proximal aortic compliance (r = 0.390, p = 0.049). Measures of arterial stiffness correlate significantly with those of endothelial function. An increase in large conduit vessel stiffness may represent either a cause or consequence of endothelial dysfunction and may explain why elevated pulse pressure is a new cardiovascular risk factor.

Effects of Probucol on Vascular Remodeling After Coronary Angioplasty

BACKGROUNDnWe have shown that probucol reduces restenosis after balloon angioplasty. Whether probucol acted via prevention of neointimal formation or improvement in vascular remodeling could not be addressed by angiography and required the use of intravascular ultrasound (IVUS).nnnMETHODS AND RESULTSnBeginning 30 days before angioplasty, 317 patients were randomly assigned to receive probucol, multivitamins, combined treatment, or placebo. Patients were then treated for 6 months after angioplasty. IVUS examination was performed immediately after angioplasty and at follow-up in 94 patients (111 segments). The cross section selected for serial analysis was the one at the angioplasty site with the smallest lumen area at follow-up. In the placebo group, lumen area decreased by -1. 21+/-1.88 mm2 at follow-up, and wall area and external elastic membrane (EEM) area increased by 1.50+/-2.50 and 0.29+/-2.93 mm2, respectively. Change in lumen area, however, correlated more strongly with the change in EEM area (r=0.53, P=0.002) than with the change in wall area (r=-0.13, P=0.49). Lumen loss was -1.21+/-1.88 mm2 for placebo, -0.83+/-1.22 mm2 for vitamins, -0.25+/-1.17 mm2 for combined treatment, and -0.15+/-1.70 mm2 for probucol alone (P=0.002 for probucol, P=0.84 for vitamins). Change in wall area was similar for all groups. EEM area increased by 0.29+/-2.93 mm2 for placebo, 0. 09+/-2.33 mm2 for vitamins only, 1.17+/-1.61 mm2 for combined treatment, and 1.74+/-1.80 mm2 for probucol only (P=0.005 for probucol).nnnCONCLUSIONSnLumen loss after balloon angioplasty is due to inadequate vessel remodeling in response to neointimal formation. Probucol exerts its antirestenotic effects by improving vascular remodeling after angioplasty.

Long-term outcomes after the atrial switch for surgical correction of transposition: a meta-analysis comparing the Mustard and Senning procedures

Most adults with regular transposition (the combinations of concordant atrioventricular and discordant ventriculo-arterial connections) have undergone either the Mustard or Senning procedure in childhood. It is unclear whether adverse events differ according to the surgery performed. With this in mind, we conducted a systematic review and meta-analysis to compare long-term outcomes. We searched systematically entries to MEDLINE and EMBASE databases from January 1966 through August 2003, supplementing the search by secondary sources. Comparative studies were required to include at least 10 patients in each cohort of Mustard or Senning procedure, and to report overall survival. Data were extracted by two independent reviewers. We used a component approach to assess quality. On the basis of assessment of heterogeneity, we then used a random-effects model for pooled analyses. In all, we included seven studies, incorporating 885 patients. We found a trend towards lower mortality for the 369 patients undergoing a Mustard procedure when compared to 474 submitted to the Senning operation, with a hazard ratio of 0.63 and 95% confidence intervals between 0.35 and 1.14 (p = 0.13). This trend increased with the size of the sample (p = 0.004). Obstruction in the systemic venous pathway was more common in those having the Mustard procedure, with a risk ratio of 3.5 and 95% confidence intervals from 1.8 to 7.0 (p < 0.001), with a trend towards greater obstruction of the pulmonary venous pathway in those undergoing the Senning procedure, 7.6% vs. 3.8% (p = 0.27). A trend towards fewer residual shunts was observed for those with Mustard baffles, 7.0% vs. 14.1% (p = 0.10). Sinus nodal dysfunction, however, was more common after the Mustard procedure. Data regarding atrial tachydysrhythmias was inconclusive. Systemic cardiac failure and functional capacity, was similar. We conclude that outcomes are not uniform among patients submitted to the Mustard and Senning procedures. Knowledge of such differences may facilitate stratification of risk and follow-up.

Statin in Combination With β-Blocker Therapy Reduces Postoperative Stroke After Coronary Artery Bypass Graft Surgery

BACKGROUNDnStatin therapy prior to coronary artery bypass surgery (CABG) has been shown to prevent perioperative events such as myocardial infarction and perioperative death. The effect of statin therapy as a preventive treatment to decrease the stroke risk unrelated to cardiac surgery is also documented. In the setting of CABG, we have found no studies reporting a preventive effect of statin therapy on neurologic outcome.nnnMETHODSnWe analyzed 6,813 patients treated by CABG surgery at our institution between 1995 and 2005 for which complete medication history including all drugs taken before and after surgery was available. We analyzed the risk factors for postoperative stroke using a multiple logistic regression analysis, more specifically looking at the effect of preoperative treatment with statin, aspirin, β-blockers, and angiotensin-converting enzyme inhibitors, alone or in combination.nnnRESULTSnAt 30 days postoperative, 94 patients suffered a new documented stroke (1.4%). Hypertension, carotid disease, diabetes, and age were all associated with a greater risk of postoperative stroke. When analyzing the four groups of drug therapy, none of the medications alone affected the stroke rate. However, upon multivariable analysis the combination of statin and β-blockers gave an odds ratio of 0.377, suggesting a strong protective effect.nnnCONCLUSIONSnBeta-blockers combined with statin confer a protective effect for stroke after CABG.

Pilot Randomized Controlled Trial of Inhaled Milrinone in High-Risk Cardiac Surgical Patients

Background: Pulmonary hypertension is a major cause of mortality and morbidity in patients undergoing valvular and complex heart surgery. Inhaled milrinone has been used for the treatment of pulmonary hypertension, but its safety and effects compared with a placebo on hemodynamics and ventricular function have not been studied in patients undergoing high-risk valvular surgery. Methods: Twenty-one high-risk cardiac surgical patients with preoperative pulmonary hypertension were randomized in a double-blind study to receive inhaled milrinone or placebo. The inhalation occurred after the induction of anesthesia and before the surgical incision and cardiopulmonary bypass. The effects on ventricular function were evaluated by means of pulmonary artery catheterization and transesophageal echocardiography. The primary outcome variable was the systemic mean arterial pressure. Results: There were 8 men and 13 women (mean age 71 ± 6 years) with a mean Parsonnet score of 32 ± 9 who underwent a total of 17 complex procedures and 6 reoperations. There were no significant changes in mean arterial pressure throughout the study. A reduction in pulmonary vascular resistance (p = 0.0458) was observed in the inhaled milrinone group, but the change in mean pulmonary artery pressure was not significant (p = 0.1655). Right ventricular end-diastolic area (p = 0.0363) and right atrial transverse diameter (p < 0.0001) increased in the control group, but not with inhaled milrinone. No significant side effects occurred in the inhaled milrinone group. Conclusion: In this high-risk cardiac surgery cohort, the use of inhaled milrinone was not associated with systemic hypotension but with a reduced pulmonary vascular resistance and prevention of the increase in right-sided cavity dimensions.

Preliminary Experience in the Use of Preoperative Echo-guided Left Stellate Ganglion Block in Patients Undergoing Cardiac Surgery

OBJECTIVEnPulmonary arterial (PA) vasoconstriction in cardiac surgery can originate from the action of combined humoral, endothelial, and sympathetic tone changes. The consequence of PA vasoconstriction is pulmonary hypertension (PHT) and, when present after cardiopulmonary bypass (CPB), can predispose to right ventricular dysfunction. Right ventricular dysfunction after CPB is a serious complication with high mortality rates. The extent to which sympathetic blockade could reduce PA vasoconstriction and reduce PHT is unknown. Pharmacologic stellate ganglion block (SGB) has been associated with a reduction in PHT, but its role and mechanism in cardiac surgery have not been described. Thus, the goal of the study was to test the hypothesis that echo-guided left SGB, performed before the induction of general anesthesia, could prevent PA pressure increases during CPB weaning.nnnDESIGNnA prospective cohort study in cardiac surgical patients.nnnSETTINGnA tertiary care university hospital.nnnPARTICIPANTSnForty cardiac surgical patients.nnnINTERVENTIONSnA left SGB was performed immediately before the induction of general anesthesia under ultrasound guidance and was compared with matched control patients. Standard hemodynamic and electrocardiographic monitoring was performed, and blood gas samples were drawn at specific predetermined time points for analysis. Rhythm disorders, echocardiographic parameters that included wall motion abnormalities, and biochemical parameters of myocardial ischemia were measured by an observer blinded to the allocated group.nnnMEASUREMENTS AND MAIN RESULTSnMarked improvement in the PaO(2)/F(I)O(2) ratio in the SGB group was observed (mean difference = 77 mmHg, p = 0.0001). There were no differences between the groups in PA pressure over time during the procedure; central venous pressure was higher in the SGB group (p =0.0184). Reductions of right ventricular fractional area change (p = 0.0331) and tricuspid annulus displacement (p = 0.0048) were observed in the SGB group. The CK-MB was 1.5 times higher in the SGB group (p = 0.0211), but no patients developed myocardial infarction.nnnCONCLUSIONSnLeft SBG was associated with improved oxygenation that could partially explain its mechanism in acute PHT. Further studies are necessary to evaluate the usefulness of this technique in patients with a high risk of PHT during separation from CPB.

Delirium After Cardiac Surgery and Cumulative Fluid Balance: A Case-Control Cohort Study

OBJECTIVEnTo assess a novel hypothesis to explain delirium after cardiac surgery through the relationship between cumulative fluid balance and delirium. This hypothesis involved an inflammatory process combined with a hypervolemic state, which could lead to venous congestion reaching the brain.nnnDESIGNnRetrospective case-control (1:1) cohort study.nnnSETTINGnUniversity-affiliated tertiary cardiology center.nnnPARTICIPANTSnCardiac surgery intensive care unit (ICU) patients.nnnINTERVENTIONSnNone.nnnMEASUREMENTS AND MAIN RESULTSnCumulative fluid balance was evaluated at 3 times: (1) upon arrival at the ICU after surgery, (2) 24 hours post-ICU arrival, and (3) 48 hours post-ICU arrival. A generalized estimated equation was used to model the association between cumulative fluid balance and delirium occurrence 24 hours later. Covariates were selected based on the statistical differences between cases and controls on delirium risk factors and clinical characteristics. The cohort included 346 patients, of which 39 (11%), 104 (30%), and 142 patients (41%) presented delirium at 24, 48, and 72 hours post-ICU arrival, respectively. The effect of time had an odds ratio (OR) of 2.14, 95% confidence interval (CI) 1.603 to 2.851, and a p value < 0.001. The cumulative fluid balance was associated with delirium occurrence (OR 1.20, 95% CI: 1.066-1.355, pu202f=u202f.003). History of neurological disorder, having both hearing and visual impairment, type of procedure, perioperative cerebral oximetry, mean pulmonary artery pressure pre-cardiopulmonary bypass (CPB), and mean arterial pressure post-CPB also contributed to delirium in the model.nnnCONCLUSIONnDelirium is associated with a cumulative fluid balance, but the extent through which this plays an etiologic role remains to be determined.

Parsonnet score and vasoactive drugs in cardiac surgery

Andre Y. Denault, Montreal Heart Institute & Universite de Montreal, Montreal, QC, Canada; Andre Y Denault, Montreal Heart Institute and Universite de Montreal; Jean Bussieres, Montreal Heart Institute and Universite de Montreal; P Couture, Montreal Heart Institute and Universite de Montreal; S Levesque, Montreal Heart Institute Coordinating Center; D Bouchard, Montreal Heart Institute and Universite de Montreal; JC Tardif, Montreal Heart Institute and Universite de Montreal; J Lambert, Montreal Heart Institute Coordinating Center;