Christoph Scharf

Ibutilide versus amiodarone in atrial fibrillation: a double-blinded, randomized study.

ObjectiveIbutilide, a class III antiarrhythmic drug, has been shown to convert atrial fibrillation to sinus rhythm more rapidly than procainamide or sotalol. Our objective was to compare the efficacy and safety of ibutilide and amiodarone in patients after cardiac surgery. DesignProspective, randomized, double-blinded study. SettingIntensive care unit of a university hospital. PatientsForty adults with an onset of atrial fibrillation within 3 hrs after admission. InterventionsBefore the administration of antiarrhythmic drugs, a 24-hr Holter electrocardiograph was attached. Patients in the ibutilide group received ibutilide 0.008 mg/kg body weight over 10 mins; treatment was repeated if atrial fibrillation or flutter persisted. If sinus rhythm was not achieved within 4 hrs, amiodarone 5 mg/kg was administered over 30 mins, followed by amiodarone 15 mg/kg over 24 hrs. Patients in the amiodarone group received amiodarone 5 mg/kg over 30 mins, followed by amiodarone 15 mg/kg over 24 hrs if atrial fibrillation or flutter continued. Measurements and Main ResultsWithin the first 4 hrs, atrial fibrillation was converted in nine of 20 patients (45%) in group ibutilide and in ten of 20 patients (50%) in group amiodarone (not significant). Mean time for conversion overall was 385 mins in group ibutilide and 495 mins in group amiodarone (not significant). In group amiodarone, the protocol was discontinued in two patients because of severe arterial hypotension. Atrial fibrillation recurred in 11 of 20 patients (55%) in group ibutilide and in seven of 20 patients (35%) in group amiodarone (not significant). Ventricular arrhythmia did not occur during the first 24 hrs of the protocol. ConclusionsIbutilide has no significant advantage over amiodarone for the conversion of atrial fibrillation to sinus rhythm in either time to conversion or conversion overall, but severe hypotension was not seen with ibutilide.

Diagnosis of Sleep-Related Breathing Disorders by Visual Analysis of Transthoracic Impedance Signals in Pacemakers

Background—Minute ventilation sensors of cardiac pacemakers measure ventilation by means of transthoracic impedance changes between the pacemaker case and the electrode tip. We investigated whether this technique might detect sleep-related breathing disorders. Methods and Results—In 22 patients, analog waveforms of the transthoracic impedance signal measured by the pacemaker minute ventilation sensor over the course of a night were visualized, scored for apnea/hypopnea events, and compared with simultaneous polysomnography. Analysis of transthoracic impedance signals correctly identified the presence or absence of moderate to severe sleep apnea (apnea/hypopnea index, AHI >20 h−1) in all patients (receiver operating characteristics, ROC=1.0). The ROC for AHI scores of ≥5 h−1 and ≥10 h−1 showed an area under the curve of 0.95, P<0.005, and 0.97, P<0.0001, respectively. Accuracy over time assessed by comparing events per 5-minute epochs was high (Cronbach &agr; reliability coefficient, 0.85; intraclass correlation, 0.73). Event-by-event comparison within ±15 seconds revealed agreement in 81% (&kgr;, 0.77; P<0.001). Conclusions—Detection of apnea/hypopnea events by pacemaker minute ventilation sensors is feasible and accurate compared with laboratory polysomnography. This technique might be useful to screen and monitor sleep-related breathing disorders in pacemaker patients.

Interaction of Sildenafil With cAMP-Mediated Vasodilation In Vivo

Abstract—Sildenafil inhibits cGMP breakdown by phosphodiesterase 5. In vitro, increased cGMP levels inhibit cAMP breakdown by phosphodiesterase 3. It is uncertain, however, whether sildenafil increases biological effects of interventions increasing cAMP levels in vivo. The objective of the present study in 40 healthy male volunteers was to determine the existence and extent of interactions with sildenafil and vasodilators acting via cGMP or cAMP or independently from these mediators on the arterial tone of the human forearm. Forearm blood flow (FBF) responses (plethysmography) to brachial artery infusions of 3 doses each of nitroglycerin, which increases cGMP levels; of isoprenaline and milrinone, which increase cAMP levels; and of verapamil as a control were assessed at baseline and 80 minutes after 50 mg oral sildenafil in 10 volunteers each. Sildenafil increased FBF (2.5±0.1 to 3.5±0.2 mL/min per 100 mL, P <0.001; n=40). At equipotent vasodilator dosages, sildenafil increased FBF from 7.5±1.0 to 9.8±1.2 mL/min per 100 mL for nitroglycerin, from 8.3±1.0 to 10.4±1.4 mL/min per 100 mL for isoprenaline, and from 8.1±1.0 to 10.3±1.2 mL/min per 100 mL for milrinone and slightly decreased FBF from 7.7±1.3 to 7.1±1.2 mL/min per 100 mL for verapamil. ANOVA for repeated measures revealed a significant interaction between sildenafil and the type of vasodilator on FBF (P <0.01). The responses of FBF to nitroglycerin, milrinone, and isoprenaline after sildenafil were similarly increased compared with the response to verapamil (P <0.01). Sildenafil markedly enhanced the arterial vasodilator response to nitroglycerin, milrinone, and isoprenaline. The response to milrinone and isoprenaline is compatible with an interaction between cGMP and phosphodiesterase 3 or an enhancement of the NO component of cAMP-mediated vasodilation, and raises the possibility of enhanced biological effects of interventions leading to increases of cAMP in the presence of sildenafil.

Impact of fusion avoidance on performance of the automatic threshold tracking feature in dual chamber pacemakers: A multicenter prospective randomized study

CANDINAS, R., et al.: Impact of Fusion Avoidance on Performance of the Automatic Threshold Tracking Feature in Dual Chamber Pacemakers: A Multicenter Prospective Randomized Study. The Autocapture algorithm enables automatic capture verification on a beat‐by‐beat basis by recognizing the evoked response signal following each pacemaker stimulus. The algorithm intends to increase patient safety while decreasing energy consumption. However, the occurrence of fusion beats, particularly during dual chamber pacing, may limit the energy saving effect of Autocapture. The aim of this multicenter, prospective, randomized study was to evaluate the impact of the Fusion Avoidance (FA) algorithm on the incidence of fusion beats. Thirty‐eight patients (mean age 69 ± 13 years) with intrinsic AV conduction who were implanted with an Affinity DR were studied. After programming a PV/AV delay of 120/190 ms, patients were randomized to FA On or Off. Each group was further randomized with respect to activation of the AutoIntrinsic Conduction Search (AICS) algorithm. The total number of beats, ventricular paced beats, fusion beats, backup pulses, and threshold searches were analyzed from 24‐hour Holter recordings. The number of total beats was comparable in both FA groups. The number of total ventricular paced beats, fusion beats, backup pulses, and threshold searches were significantly reduced in the FA On group (% reduction: 68% P < 0.001, 75% P < 0.01, 95% P < 0.01, and 94% P < 0.05, respectively). The number of ventricular paced beats with full capture was significantly reduced when AICS was activated (P < 0.05). In conclusion, the FA algorithm substantially reduces the amount of ventricular paced beats, fusion beats, unnecessary backup pulses and threshold searches, and therefore, provides added benefits in energy saving obtained by Autocapture.

European survey on efficacy and safety of duty-cycled radiofrequency ablation for atrial fibrillation

AIMS Duty-cycled radiofrequency ablation (RFA) has been used for atrial fibrillation (AF) for around 5 years, but large-scale data are scarce. The purpose of this survey was to report the outcome of the technique. METHODS AND RESULTS A survey was conducted among 20 centres from seven European countries including 2748 patients (2128 with paroxysmal and 620 with persistent AF). In paroxysmal AF an overall success rate of 82% [median 80%, interquartile range (IQR) 74-90%], a first procedure success rate of 72% [median 74% (IQR 59-83%)], and a success of antiarrhythmic medication of 59% [median 60% (IQR 39-72%)] was reported. In persistent AF, success rates were significantly lower with 70% [median 74% (IQR 60-92%)]; P = 0.05) as well as the first procedure success rate of 58% [median 55% (IQR 47-81%)]; P = 0.001). The overall success rate was similar among higher and lower volume centres and were not dependent on the duration of experience with duty-cycled RFA (r = -0.08, P = 0.72). Complications were observed in 108 (3.9%) patients, including 31 (1.1%) with symptomatic transient ischaemic attack or stroke, which had the same incidence in paroxysmal and persistent AF (1.1 vs. 1.1%) and was unrelated to the case load (r = 0.24, P = 0.15), bridging anticoagulation to low molecular heparin, routine administration of heparin over the long sheath, whether a transoesophageal echocardiogram was performed in every patient or not and average procedure times. CONCLUSION Duty-cycled RFA has a self-reported success and complication rate similar to conventional RFA. After technical modifications a prospective registry with controlled data monitoring should be conducted to assess outcome.

Sudden Cardiac Death After Coronary Artery Bypass Grafting Is Not Predicted by Signal- Averaged ECG

BACKGROUND Sudden cardiac death (SCD) is a major cause of death despite successful revascularization in patients with coronary artery disease. The signal-averaged ECG (SAECG) is a sensitive predictor of SCD and could be used in the screening strategy to select patients for prophylactic cardioverter implantation. METHODS The SAECG was recorded in 561 patients (mean age: 60 +/- 8.8 years) within 10 days of coronary artery bypass grafting. Signal-averaged ECG was performed with a bandpass filtering of 40 to 250 Hz for more than 250 beats until a noise level of 0.6 microV was achieved. All patients were followed for 5.5 +/- 1.2 years after the procedure. RESULTS Preoperative angiographic ejection fraction was at least 60% in 393 patients (72%), 40% to 60% in 126 patients (23%), and 40% or less in 28 patients (5%). There were 34 deaths, 10 of which were SCD. Late potentials were found in a total of 150 patients (27%) and were equally frequent preoperatively and postoperatively and among patients with (30%) and without (27%) SCD. The only predictors for overall mortality were age and a reduced ejection fraction. CONCLUSIONS Signal-averaged ECG did not predict prognosis in low-risk patients undergoing coronary artery bypass grafting.

Amiodarone-induced pulmonary mass and cutaneous vasculitis

21 Schroter-Kunhardt M. Nah—Todeserfahrungen aus psychiatrischneurologischer Sicht. In: Knoblaub H, Soeffner HG, eds. Todesnahe: interdisziplinare Zugange zu einem ausergewohnlichen Phanomen. Konstanz: Universitatsverlag Konstanz, 1999: 65–99. 22 Sabom MB. Light and death: one doctors fascinating account of near-death experiences. Michigan: Zondervan Publishing House, 1998: 37–52. 23 Penfield W. The excitable cortex in conscious man. Liverpool: Liverpool University Press, 1958. 24 Meduna LT. Carbon dioxide therapy: a neuropsychological treatment of nervous disorders. Springfield: Charles C Thomas, 1950. 25 Whinnery JE, Whinnery AM. Acceleration-induced loss of consciousness. Arch Neurol 1990; 47: 764–76. 26 Jansen K. Neuroscience, ketamine and the near-death experience: the role of glutamate and the NMDA-receptor. In: Bailey LW, Yates J, eds. The near-death experience: a reader. New York and London: Routledge, 1996: 265–82. 27 Greyson B. Biological aspects of near-death experiences. Perspect Biol Med 1998; 42: 14–32. 28 Grof S, Halifax J. The human encounter with death. New York: Dutton, 1977. 29 Clute HL, Levy WJ. Electroencephalographic changes during brief cardiac arrest in humans. Anesthesiology 1990; 73: 821–25. 30 Aminoff MJ, Scheinman MM, Griffing JC, Herre JM. Electrocerebral accompaniments of syncope associated with malignant ventricular arrhythmias. Ann Intern Med 1988; 108: 791–96. 31 Ring K, Cooper S. Mindsight: near-death and out-of-body experiences in the blind. Palo Alto: William James Center for Consciousness Studies, 1999. ARTICLES

Electrical Activation in the Coronary Sinus Branches as a Guide to Cardiac Resynchronisation Therapy: Rationale for a Coordinate System

Background For successful cardiac resynchronisation therapy (CRT) a spatial and electrical separation of right and left ventricular electrodes is essential. The spatial distribution of electrical delays within the coronary sinus (CS) tributaries has not yet been identified. Objective Electrical delays within the CS are described during sinus rhythm (SR) and right ventricular pacing (RVP). A coordinate system grading the mitral ring from 0° to 360° and three vertical segments is proposed to define the lead positions irrespective of individual CS branch orientation. Methods In 13 patients undergoing implantation of a CRT device 6±2.5, (median 5) lead positions within the CS were mapped during SR and RVP. The delay to the onset and the peak of the local signal was measured from the earliest QRS activation or the pacing spike. Fluoroscopic positions were compared to localizations on a nonfluoroscopic electrode imaging system. Results During SR, electrical delays in the CS were inhomogenous in patients with or without left bundle branch block (LBBB). During RVP, the delays increased by 44±32 ms (signal onset from 36±33 ms to 95±30 ms; p<0.001, signal peak from 105±44 ms to 156±30 ms; p<0.001). The activation pattern during RVP was homogeneous and predictable by taking the grading on the CS ring into account: (% QRS) = 78−0.002 (grade−162)2, p<0.0001. This indicates that 78% of the QRS duration can be expected as a maximum peak delay at 162° on the CS ring. Conclusion Electrical delays within the CS vary during SR, but prolong and become predictable during RVP. A coordinate system helps predicting the local delays and facilitates interindividual comparison of lead positions irrespective of CS branch anatomy.