Color Flow Doppler Observations on Mitral Valve Flow in Tamponade

We studied the M-mode and two-dimensional imaging of color Doppler mitral flow in eight patients with pericardial effusion and tamponade, and in ten control subjects. Pulsed-Doppler recordings of mitral flow were also obtained in all. Marked phasic changes (presumably respiratory) were consistently recorded in all patients with tamponade with respect to brightness, hue, width (duration), and length of the M-mode Doppler color stream; in these patients, phasic changes were noted in width, length, and color of the mitral flow stream on the two-dimensionalechocardiographic recording, with reciprocal changes in tricuspid flow. In the normal subjects, only minimal fluctuations in these color Doppler characteristics were present. Phasic differences in flow velocity of mitral flow by pulsed Doppler were found between the tamponade and the control groups. Large phasic fluctuations in various characteristics of color Doppler mitral flow on M-mode and two-dimensional imaging may constitute yet another echocardiographic sign of tamponade. (ECHOCARDIOGRAPHY, Volume 8, September 1991)     

Just How Stable Are Escape Rhythms after Atrioventricular Junction Ablation?

Background: Atrioventricular (AV) node ablation with implantation of a permanent pacemaker is an established mode of therapy in the treatment of atrial fibrillation. However, concern exists regarding subsequent dependency on an entirely paced rhythm and the possible sequela of unheralded pacemaker failure. Data regarding escape rhythm lability, an important feature of pacemaker dependency, are limited. Aims and Methods: The purpose of this study was twofold: (1) to determine the characteristics of escape rhythms at predefined serial time intervals following AV node ablation and pacemaker implantation, and (2) to identify risk factors predictive of unstable escape rhythms. Patients undergoing AV node ablation and pacemaker implantation were assessed for the presence or absence of an escape rhythm during pacemaker interrogation at five predetermined serial time points. Baseline demographics and comorbid conditions were evaluated as potential predictors of those with labile escape rhythms. Results : Seventy‐nine percent of the 96 patients studied had an underlying escape rhythm (≥30 beats per minute) immediately postablation. Although the percentage of patients with an escape rhythm increased at each follow‐up interval, the number of patients who consistently demonstrated an escape rhythm declined with each follow‐up, with 28% of patients lacking an escape rhythm at some time point, i.e., labile escape rhythm. There were no significant predictors of a labile escape rhythm. Conclusion: Among patients who have undergone AV node ablation and pacemaker implantation, 72% have a stable escape rhythm over time, but others are at risk for pacemaker dependency, as predicted by an underlying absent or labile escape rhythm. (PACE 2010; 939–944)     

Left‐Sided Atrial Flutter Originating in the Coronary Sinus after Radiofrequency Ablation of Atrial Fibrillation

We describe a case of atypical atrial flutter presenting 1 year after radiofrequency ablation for atrial fibrillation (AF). Electrophysiologic study showed a reentry circuit involving the inferolateral aspect of the mitral annulus and the coronary sinus (CS); however, a mitral isthmus line did not terminate the arrhythmia. Participation of the proximal CS musculature in the circuit suggested a possible target for ablation. Radiofrequency energy applications from within the CS terminated the tachycardia. Mapping and ablation within the CS should be considered in patients with post‐AF ablation arrhythmias, particularly when the mitral annulus appears to be involved in the tachycardia circuit. (PACE 2010; 33:e96–e99)     

Major Adverse Cardiac Events at Long-Term Follow-Up in Patients Treated With Single versus Multiple Stents during Single-Vessel Percutaneous Coronary Intervention

Background: Although insertion of multiple stents into a single coronary vessel during single-vessel percutaneous coronary intervention (PCI) is common, there are no data on long-term occurrence of major adverse cardiac events (MACE) in patients treated with multiple stents versus a single stent.
Methods: The incidence of MACE (death, myocardial infarction, or target vessel revascularization) during long-term follow-up was investigated in 634 patients who underwent single-vessel PCI. Of the 634 patients, 319 (50%) had a single stent, and 315 (50%) had multiple stents inserted. Stepwise Cox regression analyses were performed to identify significant independent prognostic factors for MACE.
Results: At 47-month follow-up, MACE occurred in 61 of 319 patients (19%) who had a single stent versus in 57 of 315 patients (18%) who had multiple stents (P not significant). Significant independent predictors of MACE were use of vein grafts (hazard ratio = 1.94; 95% CI, 1.24–3.03; P = 0.0038) and use of drug-eluting stents (hazard ratio = 0.49; 95% CI, 0.34–0.72; P = 0.0002).
Conclusions: At long-term follow-up of single-vessel PCI, the incidence of MACE was similar in patients with multiple or single stents inserted even after controlling for the length of stents.     

Paradoxical Change in Atrial Fibrillation Dominant Frequencies with Baroreflex‐Mediated Parasympathetic Stimulation with Phenylephrine Infusion

Baroreflex Response and AF Dominant Frequency . Introduction: Parasympathetic stimulation is known to promote atrial fibrillation (AF) through shortening of atrial refractory periods. We hypothesized that baroreflex‐mediated parasympathetic stimulation via phenylephrine (PE) infusion would increase AF rate as measured by dominant frequency (DF). Methods and Results: The protocol was performed in 27 patients (24 M, 59 ± 1 years old) prior to AF ablation. For 10 patients in AF, PE was infused until systolic blood pressure increased ≥30 mmHg. Electrograms were recorded in the left atrium before and after PE. DFs of each recording were calculated offline. Atrial effective refractory periods (ERPs) were measured before and after PE in 11 patients who were in sinus rhythm during the procedure. DFs were also measured in 6 patients in AF before and after complete parasympathetic blockade with atropine (0.04 mg/kg). PE resulted in increased RR intervals during sinus rhythm (1,170 ± 77 to 1,282 ± 85 ms, P = 0.03) and AF (743 ± 32 to 826 ± 30 ms, P = 0.03), consistent with parasympathetic effect on the sinus and AV nodes, respectively. DFs were decreased by PE in the left atrium (6.2 ± 0.2 to 6.0 ± 0.2 Hz, P = 0.004). Correspondingly, atrial ERPs significantly increased from 218 ± 13 to 232 ± 11 ms (P = 0.04). Atropine resulted in a decreasing trend in DF in the left atrium (5.9 ± 0.1 to 5.8 ± 0.1 Hz, P = 0.07). Conclusions: Despite baroreflex‐mediated parasympathetic effect, PE produced a slowing of AF along with lengthening of ERP, while parasympathetic blockade also slowed DF. It is therefore likely that the direct and indirect adrenergic effects of PE on atrial electrophysiology are more prominent than its parasympathetic effects. (J Cardiovasc Electrophysiol, Vol. 23 pp. 1045‐1050, October 2012)     

Prevalence and Predictors of Cable Extrusion and Loss of Electrical Integrity with the Riata Defibrillator Lead

Prevalence and Predictors of Riata Cable Extrusion. Introduction: Recently, a medical advisory was issued regarding the Riata and Riata ST silicone endocardial defibrillator leads (St. Jude Medical, Sylmar, CA, USA) addressing the issue of conductor cables extruding in an “inside‐out” fashion from the main body of the lead. However, little data exist to guide our management of patients with these leads. Methods and Results: A retrospective analysis was performed of 84 patients with a Riata lead who underwent cine‐fluoroscopy and electrical evaluation as part of a screening program to assess for cable extrusion. All leads screened were dual‐coil except for one single‐coil lead. Of 84 patients, 23 patients (27.4%) had fluoroscopic evidence of cable extrusion. Multivariate analysis showed that the duration of time since lead implant and the presence of multiple right ventricular leads were significantly associated with cable extrusion. All 23 patients had normal electrical parameters on routine device interrogation. Fifteen of these 23 patients (65%) with extruded cables had high‐voltage shocks within 12 months of lead screening; only one patient demonstrated postshock electrical abnormalities. Conclusions: The prevalence of cable extrusion in dual‐coil Riata leads is significantly higher at 27.4% than previously reported. The duration of time since implantation and the presence of multiple right ventricular leads are associated with cable extrusion. High‐energy shocks did not reveal electrical abnormalities in most patients with cable extrusion. (J Cardiovasc Electrophysiol, Vol. 23, pp. 1207–1212, November 2012)