Venous Obstruction in Permanent Pacemaker Patients: An Isotopic Study

Isotope venography was used to study the venous circulation proximal to the superior vena cava in two groups of pacemaker patients, one with a single endocavitary electrode and the other with multiple pacing catheters. A control group of patients without pacemakers was also studied. Numerous abnormalities were found, especially in the group with multiple electrodes. These findings suggest that venous obstruction is a common complication of endocardial pacing.     

REDUCTION OF VOLUNTARY ETHANOL INTAKE IN ETHANOL-PREFERRING sP RATS BY THE CANNABINOID ANTAGONIST SR-141716

The present study assessed the efficacy of the cannabinoid CB₁receptor antagonist, SR-141716, in reducing voluntary ethanolintake in selectively bred Sardinian alcohol-preferring (sP)rats. Ethanol (10%, v/v) and food were available in daily 4hscheduled access periods; water was present 24 h/day. The acuteadministration of a 2.5 and a 5 mg/kg dose of SR-141716 selectivelyreduced ethanol intake, whereas a 10 mg/kg dose of SR-141716reduced to a similar extent both ethanol and food intake. Theseresults suggest that the cannabinoid CB₁ receptor is involvedin the mediation of the ethanol-reinforcing effects in sP rats.     

Three Years of Cardiac Resynchronization Therapy: Could Superior Benefits be Obtained in Patients with Heart Failure and Narrow QRS?

Aim of the study: To examine the long-term effects of cardiac resynchronization therapy (CRT) in patients presenting with heart failure (HF) and QRS ≤120 ms.
Methods: This was a prospective, longitudinal study of 376 patients [mean age = 65 years, mean left ventricular (LV) ejection fraction (EF) = 29%, mean QRS duration =165 ms, mean distance covered during a 6-minute hall walk (6-MHW) = 325 m], who underwent successful implantation of CRT systems. The QRS duration at baseline was ≤120 ms in 45 patients (12%) who were not pre-selected by echocardiographic criteria of dyssynchrony, and >120 ms in the remaining 331 patients. The baseline characteristics of the 2 groups were similar. We evaluated indices of cardiac function, percentage of responders, and survival rates over a mean 28-month follow-up.
Results: Both groups experienced similar long-term increases in 6-MHW, and decreases in New York Heart Association functional class and LV end-systolic volume (all comparisons P < 0.0001 in both groups). Time interaction of changes in LVEF and percentage of responders were significantly different (P = 0.03 and P = 0.004, respectively), in favor of the narrow QRS group, where the changes were sustained and persisted at 2 and 3 years. The long-term death rate from HF was lower in the group with narrow than in the group with wide QRS complex (P = 0.04; log-rank test).
Conclusions: CRT confers considerable long-term clinical, functional, and survival benefits in patients presenting with HF and narrow QRS, not preselected by echocardiographic criteria of dyssynchrony. Caution is advised before denying CRT to these patients on the basis of QRS width only.     

Noninvasive Serial Electrophysiological Testing Using an Implanted Pacemaker for Management of Recurrent Ventricular Tachycardia

An implanted multiprogrammable pacemaker capable of performing both premature and burst stimulation can be teamed with a special external programmer for noninvasive electrophysiological testing. Such studies, combined with indications from provocative pharmacologic tests, allowed us to formulate effective antiarrhythmic therapies for three patients suffering from post-infarction, recurrent sustained ventricular tachycardia.     

Is DDD Superior to VVI Pacing in Mixed Carotid Sinus Syndrome? An Acute and Medium-Term Study

The aim of this study was to evaluate fhe importance of atrial synchronism for pacing therapy of patients with mixed carotid sinus syndrome. In 23 patients (21 m, two f: mean age 69 ± 8 years) affected by symptomatic mixed carotid sinus syndrome we performed: (1) Research of ventriculo-atrial conduction, orthostatic hypotension and pacemaker effect; and [2] Carotid sinus massage in the standing position during VVI and DVI temporary pacing. Next, ail patients received a permanent DDD pacemaker and entered a 2 month two period single-blind, randomized, cross-over study on DVI/DDD versus VVI mode. During the DVI/DDD period, no syncope occurred in any patients, minor symptoms persisted in 11 (48%) of them; during VVI period syncopes recurred in three patients, symptoms requiring the withdrawal of VVI pacing and premature DVI/DDD reprogramming in eight patients, minor symptoms in 17 (74%). A comparison between 14 patients, who preferred DVI/DDD period (Group A), and the remaining nine patients who noted no preference between DVI/DDD and VVI period (Group B) was performed on the basis of the preimplant evaluation. Group A patients had a greater pacemaker effect (-34 ± 16 mmHg vs -16 ± 14 mmHg) and a higher prevalence of symptomatic pacemaker effect (50% vs 0%), of ventriculo-atrial conduction (78% vs 44%) and of orthostatic hypotension (50% vs 11%), while the entity of the systolic pressure fall caused by carotid sinus massage was similar in the two groups either during VVI mode (Group A-51 ± 16 mmHg vs Group B-56 ± 27 mmHg) or DVI mode (Group A-38 ± 17 mmHg vs Group 3–45 ± 17 mmHg). Thus, we conclude that vasodepressor reflex of carotid sinus syndrome is not prevented by DVI/DDD pacing even if the loss of atrial synchronism resulting from WI pacing, by adding an important pacemaker effect, causes a more severe hemodynamic consequence. DVI/DDD pacing is more effective than VVI in 61% of patients. When pacemaker effect, ventriculoatrial conduction and orthostatic hypotension are present, VVI failure is possible, therefore DVI/DDD stimulation is indicated; on the contrary the evaluation of the vasodepressor reflex during WJ or DVI temporary pacing is of little value in the choice of the mode of pacing.     

Radiofrequency Catheter Ablation of the Slow Reentrant Pathway of Sustained Ventricular Tachycardia

The article reports the cases of two patients with severe coronary artery disease and associated recurrent sustained ventricular tachycardia successfully treated with radiofrequency catheter ablation. In the first patient, two different types of ventricular tachycardia (one incessant) were eliminated. In all procedures, an area of slow conduction critical for tachycardia maintenance was localized by endocardial mapping techniques. Radiofrequency energy delivered to this area could permanently modify the anatomical substrate of the arrhythmia. After single follow-ups of 19, 14, and 13 months regarding the arrhythmic entities, the patients are well and free from spontaneous recurrences.     

Effects of Ischemia and Reperfusion on QT Dispersion During Coronary Angioplasty

The effects of ischemia and reperfusion on QT interval dispersion (QTD: QT_max-QT_min in the 12-lead ECG) were analyzed in 15 patients (12 males, 57 ± 13 years) undergoing coronary angiopiasty (PTCA). AH patients had single-vessel coronary artery disease (only one ≥ 85% stenosis in a major coronary artery) and normal left ventricular function. AH were in sinus rhythm with normal atrioventricular and intraventricular conduction on the surface ECG. No patient was on therapy that could affect the QT interval. The ECG was recorded (all 12 leads simultaneously) at 50 mm/s speed before the first balloon inflation, at the end of the first inflation during PTCA, and at 30" and 60" during reperfusion following the first inflation. In order to avoid ischemic preconditioning, only recordings of the first inflation were used. In each tracing QT_max and QT_min were evaluated. All values were rate corrected using a simple linear equation (QT linear corrected = QT + 0.154 [1-RR]). QTD increased significantly during both ischemia and reperfusion. QT_max was not changed by ischemia and was increased by reperfusion. QT_min was reduced by ischemia and increased by reperfusion. These results indicate that both ischemia and reperfusion alter ventricular repolarization, inducing a less homogeneous ventricular recovery pattern.