Alteration of Human Placental Vascular Tone by Antiarrhythmic Medications In Vitro

Antiarrhythmic and Placental Vessels. Introduction : Antiarrhythmic medications are commonly used during pregnancy for treatment of maternal or fetal arrhythmias, but little is known about their effect on human placental vascular tone and, consequently, placental blood flow. The objective of this study was to evaluate the tone responses caused by antiarrhythmic medications in human placental vessels from normal term pregnancies in vitro.
Methods and Results : Isolated human placental arteries and veins from uncomplicated term pregnancies incubated in Krebs'-bicarbonate under 5% oxygen/5% carbon dioxide/balance nitrogen (PO₂ 35 to 38 torr) were exposed to cumulative doses of quinidine, procainamide, lidocaine, flecainide, propranolol, amiodarone, verapamil, digoxin, and adenosine after submaximal contraction with 5-hydroxytryptamine. The study was conducted both in the presence and absence of endothelium. The addition of the tested medications caused a significant, dose-dependent relaxation of human placental arteries and veins except for adenosine, which induced a sustained, dose-dependent contraction of human placental vessels regardless of the presence or absence of tone. Removal of the endothelium did not alter these responses.
Conclusions : Based on these results, the medications tested should have no decremental effect on placental blood flow, with the possible exception of adenosine, which causes significant. dosedependent contraction of human placental vessels in vitro. Should similar contraction be present in vivo, it may have an adverse effect on the fetus when administering adenosine to pregnant women at term or during labor.     

Body Fat Percentage of Children Varies According to Their Diet Composition

Objective To ascertain the association between diet composition and body fat percentage in 9- and 10-year-old children. Also, to examine the influence of gender, total energy intake, fitness, physical activity, and parental body mass on the relationship between diet composition and adiposity.Design Diet composition was assessed using the National Cancer Institute food frequency questionnaire, and adiposity was measured using the average of results determined using two skinfold equations. Fitness levels and physical activity were ascertained using the 1-mile run/walk test and a self-report 15-item scale, respectively.Subjects A sample of 262 children (162 boys and 100 girls, mean age=9.8±0.5 years) participated.Statistical analysis Regression analysis was used to determine the extent to which diet composition contributed to adiposity without statistical control for any potentially confounding variables. Partial correlations were calculated to assess the relationship between macronutrient intake and adiposity after potential confounders (gender, total energy intake, physical fitness, and parental body mass) were controlled statistically.Results Energy intake was positively related to adiposity. Fat intake, calculated as a percentage of total energy, was also positively related to adiposity, before and after control for potential confounding variables. Percentage of energy derived from carbohydrate was inversely related to adiposity, before and after controlling for potential confounders.Applications These findings indicate that the macronutrient intake of children, particularly dietary fat and carbohydrate intake, may play a role in adiposity, independent of the influence of total energy intake, gender, physical fitness, and parental body mass index.     

The Solution Method: 2-year trends in Weight, Blood Pressure, Exercise, Depression, and Functioning of Adults trained in Development Skills

This study describes changes observed during a 2-year period in participants enrolled in The Solution Method, a developmental skills training program for adult weight management. This Intervention is the adult application of a model of treatment previously used only in the management of pediatric obesity (The Shapedown Program). Developmental skills training integrates understandings and methods from developmental, family systems, biomedical, genetic, and behavioral theories of the etiology of obesity. Twenty-two subjects (mean age=43.4±8.5 years and mean body mass index=33.1+5.3) completed a group intervention based on this method, which was conducted by a registered dietitian and a mental health professional. Questionnaire responses indicated the extent to which their weight was a medical and/ or psychosocial risk. Subjects attended 2-hour weekly sessions for an average of 18 weeks during which they were trained in six developmental skills: strong nurturing, effective limits, body pride, good health, balanced eating, and mastery living. Data, which were collected at the beginning of treatment and at 3, 6, 12, and 24 months, included weight, blood pressure, 7-day exercise recalls, and responses to depression and functioning (psychosocial, vocational, and economic) questionnaires. Participants’ weights decreased throughout the 2-year period of the study: mean weight change was −4.2 kg (3 months), −6.0 kg (6 months), −7.0 kg (12 months), and −7.9 kg (24 months). In addition, compared with baseline values, systolic and diastolic blood pressure, exercise, and depression improved throughout the study period. These improvements were statistically significant at 24 months for weight (p<.01), systolic blood pressure (p<.02), diastolic blood pressure (p<.001), and exercise (p<.001); the results were not statistically significant for depression. Most participants reported improvement in a broad range of aspects of functioning. We conclude that this application of developmental skills training for adult weight management may produce significant long-term beneficial effects. J Am Diet Assoc. 1997;97:1133–1138.     

Safety and Effectiveness of Transvenous Lead Extraction in Octogenarians

Transvenous Lead Extraction . Introduction: As the population ages, the number of elderly patients with implantable cardiac devices referred for transvenous lead extraction will dramatically increase in Western countries. The safety and effectiveness of lead extraction in elderly patients has not been well evaluated. We report the safety and effectiveness of transvenous lead extraction in octogenarians. Methods and Results: From January 2005 to January 2011, we reviewed data from consecutive patients ≥ 80 years referred to our institutions for transvenous lead extraction because of cardiac device infection or lead malfunction. Clinical characteristics, procedural features, and periprocedural major and minor complications were compared between octogenarians and younger patients. Out of 849 patients undergoing lead extraction in the participating institutions during the study period, 150 (18%) patients were octogenarians (mean age 84 years; range 80–96; 64% males). A significantly higher percentage of octogenarians presented with chronic renal failure (55% vs 26%; P < 0.001), history of malignancy (22% vs 6%; P < 0.001), and chronic obstructive pulmonary disease (46% vs 19%; P < 0.001). Complete lead extraction rates were similar in the 2 age groups (97% in octogenarians vs 96% in patients <80 years; P = 0.39). Periprocedural death occurred in 2 (1.3%) patients ≥80 years and in 5 (0.72%) patients <80 years (P = 0.45 for comparison). No differences in terms of other periprocedural major and minor complications were found between the 2 age groups. Conclusion: Despite presenting with a significantly higher rate of comorbidities, transvenous lead extraction can be performed safely and successfully in octogenarians. (J Cardiovasc Electrophysiol, Vol. 23 pp. 1103‐1108, October 2012)     

Left Ventricular Outflow Tract Obstruction Following Mitral Valve Replacement with Carpentier-Edwards Prosthesis

Left ventricular outflow tract (LVOT) obstruction is a rare complication of mitral valve replacement. In this article, we describe three patients in whom left ventricular outflow tract obstruction occurred following Carpentier-Edwards porcine mitral valve replacement. All three patients presented with symptomatic mitral regurgitation (angiographic grade 3–4) requiring mitral valve replacement. Preoperatively there was no evidence of hypertrophic obstructive cardiomyopathy by physical exam, echocardiography, or by cardiac catheterization. At the time of surgery all three were shown to have severe mitral valve prolapse. The native anterior mitral leaflet was left intact and pledgeted to the mitral annulus. Following surgery a new systolic murmur was appreciated. Echocardiographic exam visualized obstruction of the left ventricular outflow tract by the prosthetic strut in two cases and by a flail anterior leaflet in one case. Continuous-wave Doppler measured a calculated peak gradient of 72 to 81 mmHg across the left ventricular outflow tract. In one case simultaneous Doppler and cardiac catheterization confirmed the diagnosis and severity of left ventricular outflow tract obstruction. Mechanisms of left ventricular outflow tract obstruction following Carpentier-Edwards porcine mitral valve replacement are discussed. These three cases highlight the importance of echo-Doppler techniques in understanding the mechanism of newly detected systolic murmurs following mitral valve replacement.     

Catheter Ablation in the Canine Coronary Sinus Using Radiofrequency Energy

This study was performed to evaluate the effects of radiofrequency catheter ablation in the coronary sinus as a potential means of eliminating conduction over left-sided accessory pathways in humans. Radiofrequency current at a frequency of 500 kHz was delivered by electrode catheter to two sites in the coronary sinus of each often dogs. Left coronary arteriography with venous phase visualization of the coronary sinus was performed before, immediately after, and 2 weeks following ablation. Unipolar electrograms from the ablating electrode were recorded before and immediately after ablation. Coronary arteriography revealed no evidence of damage to the adjacent left circumflex coronary artery or its branches as a result of ablation. Contrast visualization of the coronary sinus showed persistent contrast staining following ablation at two of the ablated sites. Angiographically apparent stenosis of the coronary sinus was seen both acutely and chronically in two cases. Unipolar electrogram recordings from the ablating electrode showed an increase in atrial repolarization voltage (atrial current of injury) of 1.53 ± 1.03 mV (P = 0.00004), and an increase in ventricular repolarization voltage of 0.73 ± 0.84 mV (P = 0.005). There was a 23% decrease in amplitude of atrial electrograms (P = 0.006) and a 7% decrease in amplitude of ventricular electrograms (P = 0.02) recorded from the ablating electrode following ablation. Lesions could be identified grossly and microscopically at 16 of the 20 ablated sites. Perforation of the coronary sinus did not occur. Microscopical observation showed normal healing with granulation tissue and fat necrosis extending outward from the coronary sinus involving the atrial epicardium in 13 lesions, the ventricular epicardium in 5 lesions, and the adventitia of the left circumflex coronary artery in 5 lesions. No medial or intimal involvement of the coronary artery was seen. The coronary sinus itself showed luminal organized thrombus in 4 lesions, with near occlusion of the lumen in 1 case. Radiofrequency ablation in the coronary sinus thus results in lesions of a size and extent that would be expected to successfully ablate some left-sided accessory pathways if delivered in humans. Monitoring of the unipolar electrogram provides insight into the extent of injury during ablation. In some cases, thrombosis of the coronary sinus occurs, the long-term effects of which are not known.     

DIET AND DIURETICS IN THE REDUCTION OF VOLUNTARY ALCOHOL DRINKING IN RATS

Three rats were trained and given extensive experience withan operant-conditioning model of alcohol self-administrationwhich produces pharmacologically significant drug intake. Inthis model, lever presses on a fixed ratio (FR) schedule ofreinforcement allowed the animal brief access to an 8% (w/v)alcohol solution. Drug intake was then assessed when the animalswere given a low-sodium diet and a low-sodium diet in combinationwith injections of the salt-losing diuretic furosemide (Lasix).In all cases, the low-sodium diet/furosemide treatment produceda substantial reduction in drug self-administration withoutchanging water self-administration. In one case, introducingfurosemide into the home-cage drinking water without a changeof diet also brought about a decrease in alcohol self-administration.The low-sodium diet alone was ineffective in this regard. Thesefindings corroborate earlier work using this form of treatmentand are discussed in terms of the possible functional mode(s)of action of the treatment. The viability of this treatmentfor human drug-taking is also considered.