Annibale Sandro Montenero

Role of Abnormal Pain Sensitivity and Behavioral Factors in Determining Chest Pain in Syndrome X

OBJECTIVES We sought to investigate whether patients with syndrome X have an abnormal perception of cardiac pain. BACKGROUND Previous studies have reported an increased sensitivity to potentially painful cardiac stimuli in patients with syndrome X. However, it is not clear whether this increase is due to an increased perception of pain or to an enhanced tendency to complain. METHODS We assessed cardiac sensitivity to pain in 16 patients with syndrome X and 15 control subjects by performing right atrial and ventricular pacing with increasing stimulus intensity (1 to 10 mA) at a rate 5 to 10 beats higher than the patients heart rate. False and true pacing were performed in random sequence, with both patients and investigators having no knowledge of the type of stimulation being administered. RESULTS No control subject had pacing-induced pain; conversely, 8 patients with syndrome X reported angina during atrial pacing (50%, p < 0.01) and 15 during ventricular pacing (94%, p < 0.001). During atrial stimulation, both true and false pacing caused chest pain in a similar proportion of patients (50% vs. 63%, p = 0.61), whereas during ventricular stimulation, true pacing caused chest pain in a higher proportion of patients (94% vs. 50%, p < 0.05). Pain threshold and severity of pain (1 to 10 scale) were similar during true and false atrial pacing, whereas true ventricular pacing resulted in a lower pain threshold (mean +/- SD 3.7 +/- 3.0 vs. 7.9 +/- 2.8 mA, p < 0.001) and a higher level of pain severity (7.3 +/- 2.7 vs. 3.1 +/- 3.5, p < 0.001) than did false pacing. CONCLUSIONS Patients with syndrome X frequently reported chest pain even in the absence of cardiac stimulation. Yet, in addition to this increased tendency to complain, they also exhibited a selective enhancement of ventricular painful sensitivity to electrical stimulation.

Electrograms for identification of the atrial ablation site during catheter ablation of accessory pathways.

Background: Catheter ablation of accessory pathways using radiofrequency current has been shown to be effective in patients with Wolff‐Parkinson‐White syndrome, by using either the ventricular or atrial approach. However, the unipolar electrogram criteria for identifying a successful ablation at the atrial site are not well established. Methods and Results: One hundred patients with Wolff‐Parkinson‐White were treated by delivering radiofrequency energy at the atrial site. Attempts were considered successful when ablation (disappearance of the delta wave) occurred in < 10 seconds. In eight patients with concealed pathway, the accessory pathway location was obtained by measuring the shortest V‐A interval either during ventricular pacing or spontaneous or induced reciprocating tachycardia. In 92 patients both atrioventricular valve annuli were mapped during sinus rhythm, in order to identify the accessory pathway (K) potential before starting the ablation procedure. When a stable filtered (30–250 Hz) “unipolar” electrogram was recorded, the following time intervals were measured: (1) from the onset of the atrial to the onset of the K potential (A‐K); (2) from the onset of the delta wave to the onset of the K potential (delta‐K); and (3) from the onset of the K potential to the onset of the ventricular deflection (K‐ V). During unsuccessful versus successful attempts, A‐K (51 ± 11 ms vs 28 ± 8 ms, P < 0.0001 for left pathways [LPs]; and 44 ± 8 ms vs 31 ± 8 ms, P < 0.02 for right pathways [RPs]) and delta‐K intervals (2 ± 9 ms vs ‐18 ± 10 ms, P < 0.0001 for LPs; and 13 ± 7 ms vs 5 ± 8 ms, P < 0.02 ms for RPs) were significantly longer. Conclusions: Short A‐K interval (< 40 ms), and a negative delta‐K interval recorded from the catheter positioned in the atrium are strong predictors of successful ablation of LPs and RPs. Therefore, the identification of the K potential appears to be of paramount importance for positioning of the ablation catheter, followed by analysis of A‐K and delta‐K unipolar electrogram intervals. However, it appears that the mere recording of K potential is not, per se, predictive of successful outcome, but rather the A‐K and delta‐K interval.

Arrhythmic Risk Evaluation during Exercise at High Altitude in Healthy Subjects: Role of Microvolt T‐Wave Alternans

Background: Altitude‐induced sympathetic hyperactivity can elicit rhythm disturbances in healthy subjects, in particular during exercise.

Effects of acute and prolonged administration of propafenone on internal defibrillation in the pig.

Some antiarrhythmic sodium channel blocking drugs have been found to increase the energy necessary for internal defibrillation. Propafenone is a new drug that has been shown to be efficacious in the therapy of supraventricular and ventricular arrhythmias, and is of potential use in patients with defibrillators. The effects of short-term and prolonged propafenone administration on the internal defibrillation threshold (DFT) were determined in 43 pigs randomized to one of four groups: saline infusion (n = 10); propafenone infusion (n = 10); placebo administration for 8 days (n = 10); or propafenone administration for 8 days (n = 13). Two mesh electrodes were sutured on the right lateral and left lateral epicardial surface and current was delivered from the right electrode to the left electrode. Triplicate DFTs were obtained before and at 40 and 80 minutes after infusion of drug or placebo. In pigs receiving long-term administration, after baseline DFTs were obtained the electrodes were removed and the chest was closed. Following 8 days of drug or placebo administration, DFTs were redetermined. No changes were observed in the short- or long-term control groups. DFTs were lower after propafenone administration: either short-term infusion (20 +/- 6.2 joules at baseline; 15.6 +/- 5 joules at 40 minutes, p less than 0.05; 10.2 +/- 6 joules at 80 minutes, p less than 0.001) or long-term administration (17.8 +/- 2.6 joules at baseline versus 12 +/- 3.2 joules on drug, p less than 0.002). Decreased ventricular cycle lengths were found with acute administration of propafenone. Three pigs died during long-term administration of propafenone.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison Between Two Versus Three Patches Single Pulse Shock Defibrillation in Pigs

The aim of the study was to test the hypothesis that defibrillation with a single pulse shock can be obtained at lower energy using three epicardial patches configuration (one cathode and two anodes) instead of the conventional two patches. The total surface area of the two‐ and three‐patches configuration was the same (10 cm2 vs 9.9 cm2). Epicardial spatial configuration was planned by using a computerized heart model. In ten anesthetized open‐chest pigs, ventricular fibrillation was induced by using AC current through the mesh plaque epicardial custom‐designed electrodes, and the minimum energy requirement for defibrillation was determined 15 seconds after the onset of stable ventricular fibrillation. Results were as follows (mean ± standard deviation):

Which Patients with ICD May Really Benefit from DDD Pacing, and Which Won’t?

The efficacy of implantable cardioverter-defibrillators (ICD) in preventing sudden death has been shown by several trials. Nonetheless two functions need to be improved: (1) the identification of arrhythmias other than VF (supraventricular or ventricular fibrillation) in order to reduce inappropiate shocks, (2) the quality of cardiac pacing. Dual-chamber pacing should be the stimulation method of choice in patients with depressed sinus node function, or in those who are pacemaker dependent, when effective atrial pacing and sensing can be achieved. In contrast, patients with an implatable cardioverter defibrillator (ICD) who also need antibradycardia pacing, can currently receive only fixed rate ventricular pacing, even though most of them have depressed sinus node function. Furthermore, positive hemodynamic effects of atrioventricular sequential pacing in patients with left ventricular dysfunction have been described so far [1, 2]. In fact the preservation of atrioventricular synchronization can result in a positive effect on the morbility and perhaps on the mortality of pacemaker dependent patients [1].

Implantable Cardioverter Defibrillator: A Therapy for Everyone or for Selected Patients?

The implantable cardioverter defibrillator (ICD) is an important and unique new method of potentially preventing recurrent sudden cardiac death (SCD) due to malignant ventricular arrhythmias (MVA).

Radiofrequency Ablation of Supraventricular Tachycardias in Infants and Children: When Is It Really Indicated?

Supraventricular tachycardia (SVT) is the most common sustained cardiac arrhythmia in children and adolescents, approximately 85% being due to reentrant circuits (1). Pharmacologic treatment has been proposed as the first-line therapy for frequent, sustained episodes of SVT associated with significant symptoms. However, patients refractory to medical therapy often require surgical intervention (2), which has recently been replaced by the procedure of transcatheter ablation (3).