Coronary Sinus Lead Extraction

TYERS, G.F.O., et al .: Coronary Sinus Lead Extraction. Complications are reported more frequently with the implantation of coronary sinus (CS) than other types of leads, and attempts to extract CS leads may also be associated with increased risks. The authors have performed nonthoracotomy lead extraction (LE) since 1981 and maintained a detailed database. By November 2001, 796 leads had been removed from 401 patients. We undertook review of our CS-LE experience to evaluate prevalence, safety, and efficacy. Of 14 patients referred for CS-LE, 7 were treated in the last year. In six the lead had been placed in the CS intentionally, and in eight inadvertently. One recent patient treated with biventricular pacing was septic and died before LE was undertaken. In nine men and four women (mean age 66 years) had one each CS lead and a total of 34 LEs (2.6/patient). Four CS leads had been in place for <6 months (mean 1.5 month), whereas nine had been in place for between 6 months and 27 years. Several LE methods were used, from simple traction to the use of intraluminal locking stylets and powered sheaths. Complete removal of all leads was achieved in all patients. CS-LE required a mean of 13 minutes, including 1.8 minutes of fluoroscopy. There were no serious complications during the procedures, and the mean hospital stay was 4 days. (PACE 2003; 26[Pt. II]:524–526)     

Should Unipolar Leads Be Implanted in the Atrium? A Holter Electrocardiographic Comparison of Threshold Adapted Unipolar and High Sensitive Bipolar Sensing

The accuracy ofatrial sensing plays a central role in dual chamber pacing. Recent Holter electrocardiographic studies showed a high incidence of atrial malsensing. We investigated the efficacy of bipolar atrial sensing at high sensitivity compared to threshold adapted unipolar sensing. One h undred consecutive patients with identical dual chamber pacemakers and bipolar atrial leads were investigated. Mean and individual range of 40 unipolar and bipolar telemetered atrial potentials were calculated; sensing threshold was determined by a semiautomatic sensing test. Oversensing was investigated with the help of a muscle provocation test. Twenty-four-hour Holter monitoring was performed at the highest bipolar sensitivity as well as at a unipolar sensitivity of half the measured sensing threshold. Mean atrial potential was significantly lower during bipolar mode compared to the unipolar sensing configuration, 3.66 ± 1.75 versus 3.85 ± 1.62 mV, P = 0.02. The bipolar atrial potentials showed a higher individual range than the unipolar signals, 2.44 ± 2.62 versus 1.79 ± 0.92 mV, P < 0.01. Sensing threshold did not differ significantly, 2.76 ± 1.33 versus 2.67 ± 1.29 mV. Mean oversensing threshold was 1.21 mV at unipolar configuration, whereas oversensing could not be provoked at a bipolar sensitivity of 0.5 mV. The incidence of atrial undersensing was significantly higher at threshold adapted unipolar sensing compared to bipolar sensing at highest atrial sensitivity, 35% versus 22%, P = 0.04. Oversensing did not occur at bipolar sensing, but was observed in 56% of patients at unipolar mode. Thirty-two percent of patients showed both atrial undersensing and over- sensing at the unipolar sensing configuration. The muscle provocation test reached a sensitivity of 89% and a specificity of 95% in prediction of atrial oversensing during daily life. In conclusion, unipolar atrial potentials are more stable than bipolar ones. On the other hand, bipolar atrial sensing is less prone to the perception of myopotentials. Programming a high bipolar sensitivity significantly improves atrial sensing. Th us, bipolar leads should generally be implanted in the atrium.     

Evaluation of the Anemia of Rheumatoid Arthritis

Thirty-six patients with active rheumatoid arthritis in whom anemia wasslight were investigated, in part with radioiron and radiochromium, for abnormalities which might lead to anemia.

The primary defect appeared to be a pronounced reduction of abilityto absorb iron from the intestinal tract. There was an equally marked reduction in the serum concentration of iron which could not be attributedto the slight reduction in the iron-binding capacity of the serum. Despitethe reduction level of iron in the serum, the apparent turnover of iron wasso rapid that the total clearance per day was normal or moderately elevated.However, the fraction of the iron cleared from the blood and appearing inthe circulation in newly synthesized erythrocytes was slighfly depressed.Erythrocyte survival was normal or very slightly shortened; hemolysis seemsto play no important role. The fecal excretion of radioiron, not associatedwith erythrocytes, was greatly increased in two patients in whom there wasno evidence of intestinal bleeding. A moderate increase in plasma vohime wascommon.

Submitted on August 3, 1962 Accepted on November 3, 1962     

Rate-responsive pacing as compared to fixed-rate VVI pacing in patients after ablation of the atrioventricular conduction system

In 44 patients with supraventricular arrhythmias various pacemakerswere studied after closed-chest ablation of the atrioventricularconduction system. There were 22 patients with a rate-programmableVVI pacemaker (Group I), 15 patients with an activity mode (ACTIVITRAX8400) (Group II) and seven patients with a QT-mode pacemaker(QUINTECH 911) (Group III). To study both physical work capacityand heart-rate behaviour, exercise testing was performed usinga treadmill. Sixteen patients in Group I (72·7% complainedof shortness of breath during exercise in comparison to fourpatients (26·7%) in Group II and three patients (42·9%)in Group III. Normal physical work capacity was observed inthree of 22 patients (13·6%) in Group I and in all patientsin Groups II and III. The heart rate both increased and decreasedmore rapidly at the onset and end of the stress test, respectively,in patients with activity-mode compared to patients with QT-modepacing systems. These data show that, despite successful His-bundleablation, both dyspnea and decreased work capacity are observedwhen VVI pacemakers are used. In contrast, the use of rate-responsivepacing systems leads to better cardiac performance.     

Report on Childhood Obesity in China （8）： Effects and Sustainability of Physical Activity Intervention on Body Composition of Chinese Youth

Objectives To determine whether a large-scale physical activity intervention could affect body composition in primary school students in Beijing, China. Methods The study design was one-year cluster randomized controlled trial of physical activity intervention （20 rain of daily exercise in the classroom） with an additional year of follow-up among 4 700 students aged 8-11 years at baseline. Results After the one-year intervention, BMI increased by 0.56 kg/m2 （SD 1.15） in the intervention group and by 0.72 kg/m^2 （SD 1.20） in the control group, with a mean difference of-0.15 kg/m^2 （95% CI： -0.28 to -0.02）. BMI z score decreased by -0.05 （SD 0.44） in the intervention group, but increased by 0.01 （SD 0.46） in the control group, with a mean difference of-0.07 （-0.13 to -0.01）. After another year of follow up, compared to the control group, children in the intervention group had significantly lower BMI （-0.13, -0.25 to -0.01 ）, BMI z score （-0.05, -0.10 to -0.01）, fat mass （-0.27 kg, -0.53 to -0.02） and percent body fat （-0.53, -1.00 to -0.05）. The intervention had a more pronounced effect on weight, height, BMI, BMI z score, and body composition among obese children than among normal weight or overweight children. Compared to the control group, the intervention group had a significantly higher percentage of children who maintained or reduced their BMI z score at year 1 （P-0.008） and year 2 （P=-0.04）. Conclusions These findings suggest that 20 min of daily moderate to vigorous physical activity during the school year is a feasible and effective way to prevent excessive gain of body weight, BMI, and body fatness in primary school students.