Pulse Width Dependent Increase in the Pacemaker Automatic Interval

From a total of 51 patients equipped with rate and pulse width adjustable pulse gen erators (Microlith-P 0505, Microthin-PI 0522) implanted over the last 3 years, 10 (19.6%) showed an un expected drop in pacemaker pulse rate during pulse width programming. For one of the pulse gen erators used (Microthin-PI 0522), unexpected rate decrease occurred in 7/13 cases (53.8%). For all ex cept one patient, decrease in pacemaker pulse rate corresponded with the total refractory period of the pulse generator (320 ms), at a certain pulse width when rate drop first occurred. In seven of the patients the pulse generator automatic interval was extended from 13 ms to 171 ms beyond the re fractory period. In two patients it was necessary to replace the pulse generators. Our study strongly proves that this abnormal pacemaker functioning is a result of sensing of the polarization voltage at the pacemaker electrode/tissue interface and/or the T-wave. The polarization voltage is highly dependent on the total pacemaker electrode/tissue interface impedance. Using typical values for pulse genera tor output and input resistance and output capacitance, Faraday resistance, Helmholtz capacitance and tissue resistance at the electrode/tissue interface it was shown mathematically that in some cases the polarization voltage alone would be of sufficient amplitude and slew rate for pacemaker inhibi tion. The study demonstrates an urgent need for change in the filter characteristics by making the pulse generators less sensitive in the low frequency region and reducing the polarization voltage by reducing the output circuit capacitance. (PACE, Vol. 5, May-June, 1982)     

Functional Response to Cardiac Resynchronization Therapy is Associated with Improved Clinical Outcome and Absence of Appropriate Shocks

Clinical Outcome in Cardiac Resynchronization Therapy (CRT) Functional Responders . Introduction : We evaluated clinical outcome and incidence of (in)appropriate shocks in consecutive chronic heart failure (CHF) patients treated with CRT with a defibrillator (CRT‐D) according to functional response status. Furthermore, we investigated which factors predict such functional response. Methods and Results : In a large teaching hospital, 179 consecutive CHF patients received CRT‐D in 2005–2010. Patients were considered functional responders if left ventricular ejection fraction (LVEF) increased to ≥35% postimplantation. Analysis was performed on 142 patients, who had CRT‐D as primary prevention, complete data and a baseline LVEF <35%. Endpoints consisted of all‐cause mortality, heart failure (HF) hospitalizations, appropriate shocks and inappropriate shocks. Median follow‐up was 3.0 years (interquartile range [IQR] 1.6–4.4) and median baseline LVEF was 20% (IQR 18–25%). The functional response‐group consisted of 42 patients. In this group no patients died, none were hospitalized for HF, none received appropriate shocks and 3 patients (7.1%) received ≥1 inappropriate shocks. In comparison, the functional nonresponse group consisted of 100 patients, of whom 22 (22%) died (P = 0.003), 17 (17%) were hospitalized for HF (P = 0.007), 17 (17%) had ≥1 appropriate shocks (P = 0.003) and 8 (8.1%) received ≥1 inappropriate shocks (P = 0.78). Multivariable analysis showed that left bundle branch block (LBBB), QRS duration ≥150 milliseconds and no need for diuretics at baseline are independent predictors of functional response. Conclusion : Functional responders to CRT have a good prognosis and rarely need ICD therapy. LBBB, QRS duration ≥150 milliseconds and lack of chronic diuretic use predict functional response. (J Cardiovasc Electrophysiol, Vol. 24, pp. 316‐322, March 2013)     

Expression of Human IL-2 Receptor α- and β-Chains using the Baculovirus Expression System

The genes encoding the α- and β-chains of the human interleukin-2 receptor were expressed in lepidopteran insect cells using the baculovirus expression vector system. The corresponding genes were inserted under the polyhedrin promoter of the Autographa california nuclear polyhedrosis virus and expressed in the Spodoptera frugiperda insect cell line during viral infection. The recombinant receptor proteins were identified in the insect cell lysates by using protein dot blot and ELISA techniques. At 36 h post infection the corresponding proteins were clearly detected using anti-IL-2 α- and β-receptor-specific antibodies. A large amount of the α-chain was also found in the supernatant culture media at 72 h post infection and metabolic labelling with [³⁵S]-methionine indicated that it was proteolytieally cleaved into a 32 kDa soluble form. A similar soluble or secreted form of the β-chain was. however, not observed. Both receptor proteins were expressed on the surface of the insect cells as determined by flow cytometry analysis. Studies performed with the different IL-2 receptor forms (α- and β-chains alone or in combination) in the presence or absence of rIL-2 suggest that the receptor proteins when expressed in infected insect cells are non-functional with respect to tyrosine phosphorylation.     

An alternative treatment in cases with advanced localized attrition

A combined orthodontic/prosthetic treatment of patients with advanced localized attrition has been described. In one patient the effect of the orthodontic treatment upon the morphological face height has been studied using an X-ray cephalographic technique and the results have been discussed.     

Long-term β1-Selective Adrenergic Blockade and Adrenergic Receptors in Human Subcutaneous Adipocytes

ABSTRACT. Wahrenberg H, Arner P, Engfeldt P, Haglund K, RÖssner S, Östman J. (Department of Internal Medicine and Research Centre, Huddinge Hospital, Karolinska Institute, Huddinge, and Department of Internal Medicine, Karolinska Hospital, and King Gustaf V Research Institute, Stockholm, Sweden.) Long-term β₁-selective adrenergic blockade and adrenergic receptors in human subcutaneous adipocytes. The influence of β-adrenergic blockade with metoprolol, a β₁-selective agent, on the adrenergic regulation of lipid mobilization was explored in subcutaneous adipocytes removed from 13 patients with essential hypertension. Treatment with metoprolol, which was associated with adequate β-adrenergic blockade and an antihypertensive effect, resulted in a significant increase (p<0.05) in the binding of the β-adrenergic antagonist (-)-(³H)-dihydroalprenolol and a 50% increase (p<0.01) in the maximum lipolytic response to the β-adrenergic agonist isopropylnoradrenaline. In 7 patients with normotriglyceridaemia the total plasma triglyceride level increased significantly (p<0.025) during metoprolol treatment, a change that was due to an increase in the very low density lipoprotein triglycerides. The findings suggest that chronic treatment with the β₁-selective adrenergic blocker metoprolol leads to a significant increase in β-adrenoceptor density and an increase in the lipolytic response to β-adrenergic agonists. This latter finding may, in some measure, account for the increased plasma triglyceride level observed.     

Coarctation of the Abdominal Aorta in Elderly Patients

ABSTRACT Coarctation of the abdominal aorta as a congenital disease is infrequent, the diagnosis mostly being made at an early age because of renovascular hypertension. Patients who reach the age of 40 more often tend to have the problems located distally to the renal arteries. A 66-year-old female is described, who developed an aortic occlusion, renovascular hypertension and uremia. She was cured with a bifurcation graft and a patch angioplasty of a stenotic renal artery and nephrectomy of the contralateral kidney with an occluded artery without refilling. A literature survey is made of patients older than 40 years.     

Cardiovascular Risk Factors in the Northern Sweden MONICA Study

ABSTRACT In the WHO MONICA Study, determinants and trends in cardiovascular disease are monitored during a 10-year period in 40 centers in 27 countries. The Northern Sweden MONICA Center is located furthest to the north of all participating centers. In this report, baseline data on cardiovascular risk factors are presented. In the first population screening, 1625 of 2000 (81%) invited individuals participated. Diastolic blood pressure ≤90 mmHg was recorded in 19% and 9% were on drug treatment for hypertension. Median cholesterol level was 6.10 mmol/1 and the frequency of hypercholesterolemia was high. A body mass index of ≤30, indicating severe obesity, was observed in 9%, a lower proportion than in most other European populations. Among men, the total proportion of tobacco consumers was 49%, including 22% snuffers. Of the women, 31% were tobacco consumers, very few being snuffers. Women had, in general, a more favorable cardiovascular risk factor profile up to the age of 45. Thereafter, the two genders were similar. By international comparisons, the population in northern Sweden is characterized by high serum cholesterol levels, intermediate blood pressure levels, a relatively low prevalence of severe obesity and a high consumption of smokeless tobacco.