Synchronous Ventricular Pacing without Crossing the Tricuspid Valve or Entering the Coronary Sinus—Preliminary Results

Background: Right ventricular apical (RVA) pacing promotes tricuspid regurgitation (TR), electromechanical dyssynchrony, and ventricular dysfunction. We tested a novel intramyocardial bipolar lead to assess whether stimulation of the atrioventricular septum (AVS) produces synchronous ventricular activation without crossing the tricuspid valve (TV). Methods: A lead with an active external helix and central pin was placed on the AVS and the RVA in three dogs. High‐density electroanatomic (EA) mapping was performed of both ventricles endocardially and epicardially. Intracardiac echocardiography was used to access ventricular synchrony. Results: The lead was successfully deployed into the AVS in all cases with consistent capture of the ventricular myocardium without atrial capture or sensing. The QRS duration was less with AVS compared with RVA pacing (89 ± 4 ms vs. 100 ± 11 ms [P < 0.0001, GEE P = 0.03]). There was decreased delay between color Doppler M‐mode visualized peak contraction of the septum and the mid left ventricular free wall with AVS compared with RVA pacing (89 ± 91 ms vs. 250 ± 11 ms [P < 0.0001, GEE P = 0.006]). Activation time between the mid septum and mid free wall was shorter with AVS versus RVA pacing (20.4 ± 7.7 vs. 30.8 ± 11.6 [P = 0.01, GEE P = 0.07]). The interval between QRS onset to earliest free wall activation was shorter with AVS vs. RVA pacing (19.2 ± 6.4 ms vs. 31.1 ± 11.7 ms [P = 0.005, GEE P = 0.02]). Conclusion: The AVS was successfully paced in three dogs resulting in synchronous ventricular activation without crossing the TV.     

Update on Interventions in Saphenous Vein Grafts

Interventions in saphenous vein grafts present some of the most challenging problems in preventing acute complications and limiting restenosis. Available options include repeat bypass surgery, balloon angioplasty, directional atherectomy, transluminal extraction atherectomy, rotational atherectomy, laser angioplasty, and stenting. Stenting appears to provide the best acute and long-term results. Debulking with directional atherectomy prior to stenting may be helpful but its role is unproven. With any device, it is essential to attain the lowest possible residual stenosis with the least amount of manipulation. Complications with vein graft interventions are most commonly related to distal embolization, which occurs most frequently in older vein grafts with diffuse disease, large plaque volume or thrombus, or those with total occlusion. Use of thrombolytics, glycoprotein Ilb/IIIa receptor inhibitors, and thrombectomy devices may be helpful when thrombus is present. Calcium channel blockers may be beneficial when embolization of plaque debris results in slow flow or no-flow during interventions.     

Anatomy of the Coronary Sinus and Epicardial Coronary Venous System in 620 Hearts: An Electrophysiology Perspective

Anatomy of the Coronary Venous System . Introduction: Cannulation of the coronary sinus (CS) is a prerequisite for left ventricular (LV) pacing and certain ablation procedures. The detailed regional anatomy for the coronary veins and potential anatomic causes for difficulty with these procedures has not been established. Methods and Results: Therefore, we performed macroscopic measurements in 620 autopsied hearts (mean age 60 ± 23 years, 44% female). The CS was preserved for analysis in 96%. Sixty‐three percent had a Thebesian valve that covered the posterior aspect of the CS ostium with extension to the superior (50%) and inferior aspects (18%) and was obstructive with fenestrations in 3 specimens. Partial or near occlusive valves were present occasionally at the ostium of the great cardiac vein (Vieussens; 8%) and middle cardiac vein (5%). Ninety‐three percent had left atrial branches, and 41% had at least one branch with lumen > 3 French. For CRT lead placement, the mid‐lateral LV was accessible from the middle cardiac vein (20%), the left posterior vein (92%) or the anterior interventricular vein (86%). Among specimens where the left phrenic nerve was preserved it crossed the LV mid‐lateral wall in 45%. Conclusions: Epicardial coronary vein anatomy is variable, and the mid‐lateral LV wall can potentially be accessed through various tributaries of the epicardial veins. The orientation of the Thebesian valve favors cannulation of the CS from an anterior (ventricular) and inferior approach. Anterobasal, mid‐lateral, and inferior apical LV coronary veins lie in proximity to the course of the phrenic nerve. (J Cardiovasc Electrophysiol, Vol. 24, pp. 1‐6, January 2013)     

Acute Urinary Tract Toxicity of Tetraethylorthosilicate in Rats

Acute stomach, kidney, and bladder toxicity was evaluated inF344 rats after gastric gavage of tetraethylorthosilicate (TES)at daily doses of 0, 0.111, 0.223, and 0.333 g. Five rats ofeach sex at each dose were sacrificed after 1, 2, and 4 days.In TES-treated groups, silicate accumulated in the stomach glandsand the muscle layer of the forestomach and glandular stomach.Serum chemistries demonstrated acute onset of renal failure.In the kidneys, acute tubular necrosis, accumulation of silicates,and superficial necrotizing papillitis were observed. In therenal pelvis and bladder, there was urothelial simple hyperplasia,focal erosion of the mucosa, edema, and inflammation. Theseacute toxic changes were dose and time dependent, but significantsex differences were not observed. The microscopic changes inthe urothelium were similar to those observed following administrationof high doses of sodium saccharin to male rats in which urinarysilicate precipitate and crystals form.     

Aneurysm of the Left Main Coronary Artery

Aneurysms of the left main coronary artery are rare; the estimated incidence is < 0.1%. They are usually associated with atherosclerotic coronary artery disease, and are incidental discoveries at the time of cardiac catheterization for the evaluation of cardiac symptoms. This report describes the clinical course of a patient with an isolated left main coronary artery aneurysm and generalized atherosclerosis.     

Propofol reduces the incidence of vomiting after tonsillectomy in children

We compared the effect of a propofol-based anaesthetic to an isoflurane-based anaesthetic on the incidence of postoperative vomiting in children following tonsillectomy. Thirty-nine children were enrolled in the study and randomized to receive one of the proposed anaesthetics. All patients underwent a mask induction with halothane, nitrous oxide, and oxygen. Intravenous access was established and all children received fentanyl (2–4 μg·kg^-1) i.v., mivacurium (0.3 mg·kg^-1) i.v. and acetaminophen (10–15 mg·kg^-1) p.r. Following tracheal intubation, patients received either isoflurane (0.8–1.6%) or propofol (120–180 μg·kg^-1 min^-1) i.v. with nitrous oxide 70%/oxygen 30% for maintenance of anaesthesia. Vital signs were maintained within 20% of baseline. All patients were extubated in the operating room. PACU nursing staff recorded episodes of vomiting for 4–6 h prior to discharge. A telephone interview the following day was also used for data recovery. Age, sex, and duration of the procedure were not significantly different between the two study groups. Of 19 patients who received propofol, four vomited (21%); in contrast, of the 20 patients who received isoflurane, 11 vomited (55%). This difference is significant (P= 0.048 two-tailed Fisher's Exact Test). These data suggest that using propofol for anaesthesia can diminish the incidence of vomiting following tonsillectomy.     

Oral and Intravenous Amiodarone for Atrial Fibrillation-Flutter

Amiodrone is a benytfuran derivative with class III anti arrhythmic effects. It has also been reported to convert atrial fibrillation and flutter to sinus rhythm and is highly effective for the prevention of atrial fibrillation (especially of the paroxysmal form) with an overall efficacy in the range of 70–50%. This high degree of efficacy was obtained in a majority of patients who had already failed various conventional anti arrhythmic agents. The mechanism of arrhythmia termination by intravenous amiodarone is not clear. The slowing in ventricular response, which most probably improves cardiac hemodynamics, has an indirect salutary effect. Despite the fact that none of the published reports on intravenous amiodarone used a placebo control group, these studies suggest that intravenous amiodarone has an important role in the acute treatment of atrial fibrilation with fast ventricular response.