Unexpectedly high defibrillation thresholds in an active can implantable cardioverter defibrillator system.

This case report describes a patient undergoing defibrillator generator replacement in whom the defibrillation thresholds were significantly higher with a can-active system than with a non-active can system.

Activated factor VII levels in patients with angiographically confirmed coronary artery disease.

We have examined factor VIIa levels in consecutive consenting patients undergoing coronary angiography (n = 702) to determine if levels are related to the presence of coronary arterial narrowing and to the degree and extent of that narrowing. Both men and women with clinically defined coronary artery disease (> or = 50% stenosis in at least 1 vessel) had factor VIIa levels that were similar to men and women with less stenosis or normal coronary arteries.

Interference with cardiac pacemakers by cellular telephones.

BACKGROUND: A growing body of evidence suggests that electromagnetic interference may occur between cardiac pacemakers and wireless hand-held (cellular) telephones, posing a potential public health problem. Electromagnetic interference may occur when the pacemaker is exposed to an electromagnetic field generated by the cellular telephone. METHODS: In this multicenter, prospective, crossover study, we tested 980 patients with cardiac pacemakers with five types of telephones (one analogue and four digital) to assess the potential for interference. Telephones were tested in a test mode and were programmed to transmit at the maximal power, simulating the worst-case scenario; in addition, one telephone was tested during actual transmission to simulate actual use. Patients were electrocardiographically monitored while the telephones were tested at the ipsilateral ear and in a series of maneuvers directly over the pacemaker. Interference was classified according to the type and clinical significance of the effect. RESULTS: The incidence of any type of interference was 20 percent in the 5533 tests, and the incidence of symptoms was 7.2 percent. The incidence of clinically significant interference was 6.6 percent. There was no clinically significant interference when the telephone was placed in the normal position over the ear. Interference that was definitely clinically significant occurred in only 1.7 percent of tests, and only when the telephone was held over the pacemaker. Interference was more frequent with dual-chamber pacemakers (25.3 percent) than with single-chamber pacemakers (6.8 percent, P<0.001) and more frequent with pacemakers without feed-through filters (28.9 to 55.8 percent) than with those with such filters (0.4 to 0.8 percent, P=0.01). CONCLUSIONS: Cellular telephones can interfere with the function of implanted cardiac pacemakers. However, when telephones are placed over the ear, the normal position, this interference does not pose a health risk.

Fibrinogen levels in women having coronary angiography.

Fibrinogen has emerged as a risk factor for coronary artery disease in men that equals cholesterol in importance. It is known to play an important role in reparative processes, and evidence is accumulating that fibrinogen/fibrin accumulates at the site of minimal vascular injury. Fibrinogen contributes significantly to blood viscosity and its adherence to endothelium may mediate progression of atheromatous lesions. This study was designed to examine a number of markers of risk in a consecutive series of cardiology patients undergoing coronary catheterizations over a 15-month period. This article examines the level of fibrinogen in relation to the number of reported coronary stenoses and disease severity in a series of Caucasian female patients (n = 101). Women were classified as diseased if they had at least 1 lesion > or = 25% in the coronary anatomy and nondiseased if they had no lesions > or = 25%. The number of reported lesions correlates significantly with fibrinogen levels (r = 0.36, p = 0.0002). Women with fibrinogen levels > or = 283 mg/dl had a 3.2-fold increased risk (95% confidence interval 1.2 to 9.1) of having at least 1 stenosis > or = 25% after adjusting for age and diabetic status. Smoking and body mass index did not differ by disease status and thus did not confound the finding. Mean fibrinogen levels showed a progressive positive association with increasing clinically defined vessel involvement (stenosis > or = 50%).

Measurement of pulmonary artery diastolic pressure from the right ventricle.

OBJECTIVES: This study evaluated the feasibility of estimating pulmonary artery end-diastolic pressure from within the right ventricle. If feasible, this could have important implications for long-term hemodynamic monitoring. BACKGROUND: Right ventricular pressure at the time of pulmonary valve opening closely approximates pulmonary artery end-diastolic pressure. Because maximal first derivative of right ventricular pressure (dP/dt) can be easily measured, if it occurs at or very near pulmonary valve opening, right ventricular pressure at maximal right ventricular dP/dt would be an estimation of pulmonary artery end-diastolic pressure. METHODS: In 10 patients undergoing routine right and left heart catheterization, simultaneous measurements were made using micromanometers in the right ventricle and pulmonary artery at baseline, during isometric work and Valsalva maneuver. Right ventricular pressure at maximal right ventricular dP/dt was considered the estimated pulmonary artery end-diastolic pressure and was compared with the actual pulmonary artery end-diastolic pressure. RESULTS: At baseline, estimated and actual pulmonary artery end-diastolic pressures were (mean +/- SD) 17.7 +/- 6.6 and 16.7 +/- 6.7 mm Hg, respectively (p = NS). During isometric stress, estimated and actual pulmonary artery end-diastolic pressures were 30.4 +/- 12.7 and 28.4 +/- 10.1 mm Hg, respectively (p = NS). During Valsalva maneuvers, estimated and actual pulmonary artery end-diastolic pressures were 36.5 +/- 17.8 and 38.0 +/- 16.1 mm Hg, respectively (p = NS). CONCLUSIONS: Although more extensive testing is necessary to evaluate validity in different physiologic and pathologic situations, it appears that right ventricular pressure at maximal right ventricular dP/dt can provide accurate estimation of pulmonary artery end-diastolic pressure.

The right atrial free wall: an alternative pacing site.

A major advantage of active fixation permanent pacing leads is their ability to be actively attached in areas where conventional passive fixation leads cannot be. In a review of records of 134 consecutive patients requiring dual chamber pacing, all of whom received active fixation atrial leads, 56 had right atrial appendage (AA) pacing and 78 had right atrial free-wall (AFW) pacing. Acute electrical parameters including sensed P wave amplitude (AA = 5.6 +/- 2.3 mV, AFW = 5.5 +/- 2.3 mV), slew rate (AA = 1.21 +/- 0.77 V/sec, AFW = 1.20 +/- 0.74 V/sec), stimulation thresholds (voltage and current) including rheobase voltage (AA = 0.6 +/- 0.2 V, AFW = 0.6 +/- 0.2 V), and pacing impedance (AA = 516 +/- 89 ohms, AFW = 504 +/- 84 ohms) were similar in both groups. There were two dislodgements (atrial appendage group) and no episodes of clinically important perforation or diaphragmatic stimulation. The free wall of the right atrium appears to be an excellent alternative pacing site to the appendage.

Kissing balloon technique in complex PTCA: single guiding catheter and dual wire rapid exchange system.

This report is a description, based on four cases, of a variation from previously described approaches for accomplishing the "kissing balloon" technique for complex PTCA. We describe a case in which a single guiding catheter is utilized in combination with two over-the-wire monorail type balloon catheters allowing use of standard length (175 cm) guidewires. Various combinations of balloon diameters are described. We believe this approach has significant advantages over other techniques, principally in its rapid and easy usage.

Cross-talk in bipolar pacemakers.

Investigation of dual chamber pacing and sensing interactions at high rates is becoming increasingly important with the advent of sensor driven dual chamber pacemakers. The present study was designed to investigate the pacemaker and lead interactions that will affect cross-talk during high rate atrial and ventricular pacing. The study was divided into two phases, phase one investigated the mechanisms of cross-talk using standard pacemaker circuitry and various electrode types in a canine model. In six dogs with complete heart block, dual chamber pacing was carried out with four lead types at increasing pacing rates, while output of the ventricular sense amplifier of a pacemaker breadboard was monitored. Ventricular sense amplifier output signals (n = 332) progressively increased from 31.5 +/- 18.3 mV at 100 ppm to 102 +/- 55 mV at 160 ppm. Smooth platinum-iridium and platinized leads were statistically different at higher pacing rates (P less than 0.05). This signal level is sufficient to lead to a ventricular sensing event. In a second phase of the study, the incidence of cross-talk at high pacing rates was studied in patients with implantable dual chamber bipolar pacemakers. In 166 clinical trials on 106 patients with the same pacemaker, there was evidence of cross-talk in 1/59 cases at 110 ppm and 3/47 at 130 ppm, but none at higher rates.(ABSTRACT TRUNCATED AT 250 WORDS)

Increased frequency of cytomegalovirus infection in children in group day care.

The prevalence of cytomegalovirus (CMV) infection in 103 children attending a single day care center was compared with that of 62 children kept at home. Demographic features of the day care group were similar to those of the home care group; in both groups, most of the children were white, were from middle-income families with two or fewer children, and had parents with 15 or more years of education. Ten of 57 (18%) children in home care had serum antibody to cytomegalovirus (CMV) and 2/25 (8%) had viruria. In contrast, 59/103 (57%) of children from the day care center were shedding CMV in urine or saliva. Although less than 10% of infants aged less than 1 year were excreting CMV, 78% of infants studied between 12 and 18 months of age had CMV isolated from a saliva or urine specimen. Group day care appears likely to result in early acquisition of CMV. Excretion of CMV by children in day care centers could result in transmission of the virus to susceptible day care workers or mothers, with the potential risk of fetal infection.

Direct endocardial recording from an accessory atrioventricular pathway: localization of the site of block, effect of antiarrhythmic drugs, and attempt at nonsurgical ablation.

We recorded a discrete 0.95 mV potential consistent with accessory atrioventricular pathway (AP) activation during serial electrophysiologic studies in a patient with Ebstein's anomaly and Wolff-Parkinson-White syndrome. Bipolar pacing from the catheter electrode in which the AP potential was recorded resulted in a stimulus-ventricle interval identical to the AP-ventricle interval during antegrade conduction, and a stimulus-atrium interval identical to the AP-atrium interval during retrograde conduction. With the patient in the drug-free state, antegrade AP block during atrial pacing and retrograde AP block during ventricular pacing occurred distal to the AP potential (AP-ventricle junction and AP-atrium junction, respectively), supporting the "impedance mismatch" hypothesis. Procainamide and disopyramide each lengthened the antegrade AP effective refractory period by affecting the AP-ventricle junction (possibly by decreasing the current generated by the AP). Both drugs also lengthened the retrograde AP effective refractory period but produced a greater effect on the ventricle-AP junction than on the AP-atrium junction, suggesting marginal geometry of the former. R wave synchronous shocks of 160 and 320 W-sec delivered between the catheter electrode recording the largest unipolar AP potential and a skin electrode produced transient, complete, antegrade block over the AP, suggesting the feasibility of this new nonsurgical technique for AP ablation.

Impaired lymphocyte transformation response to cytomegalovirus and phytohemagglutinin in recipients of renal transplants: association with antithymocyte globulin.

Cell-mediated immunity was assessed in 38 seropositive recipients of renal transplants by measuring the in vitro lymphocyte transformation response (LTR) to cytomegalovirus (CMV) and to phytohemagglutinin; results were correlated with clinical course, viral excretion, and immunosuppressive treatment. Thirteen seropositive controls all responded to CMV with a mean stimulation index of 31 +/- 6; 14 seronegative controls all had stimulation indices of less than 3. LTR to CMV was found to require both thymus-derived lymphocytes and macrophages. Before immunosuppression, responses of patients were similar to those of controls. After renal transplantation mean LTRs to CMV were dramatically reduced up to 18 months postoperatively, especially in patients treated with antithymocyte globulin. Viremia and CMV-related illness were significantly more frequent in recipients of antithymocyte globulin. Although there was only a rough correlation between clinical events and LTR to CMV, five deaths were noted among seven patients (all treated with antithymocyte globulin) who failed to respond to phytohemagglutinin on two consecutive tests.

Oesophagitis--a complication of inhaled steroid therapy.

The hazards of steroid therapy, both inhaled and oral, in the asthmatic patient are well recognized. The following case report presents an unusual complication of steroid therapy, namely, that of a concomitant Candida and Herpes simplex oesophagitis occurring in a steroid-dependent 15-year-old asthmatic who had been maintained on inhaled beclomethasone for approximately 15 monts. Oesophagoscopy revealed a 'cottage cheese' appearance of the distal oesophagus. Cultures of the biopsy specimens obtained during oesophagoscopy grew Candida and Herpes simplex virus. Lymphocyte stimulation studies were consistent with a primary cellular response, although the neutralizing antibody titres to the Herpes simplex virus were initially high and remained stable throughout the illness and convalescent period. The patient responded well to oral nystatin therapy and developed no evidence of disseminated herpes. Eleven months after the initial episode, the patient's oropharynx cultured Herpes simplex virus but not Candida. Doctors who care for asthmatic patients need to be aware of the possibility of a herpetic as well as a candidal oesophagitis as a significant complication of inhaled steroid therapy.

Development of adverse sequelae in children born with subclinical congenital Toxoplasma infection.

Most infants born with congenital Toxoplasma infection are asymptomatic in the newborn period, and therefore their infection is not recognized. We performed follow-up evaluations on 24 such children. The mean age of these children at least examination was 8.5 years. In group I (13 children), the diagnosis was made prospectively. In group II (11 children), no symptoms or signs were noted in the newborn period and the diagnosis was made only after the first sign developed. Eighty-five percent of the children in group I and all of the children in group II have developed chorioretinitis. In group I, three children (23%) have unilateral blindness; in group II, three children (27%) and five children (45%) have unilateral and bilateral blindness, respectively. One child (8%) in group I and two children (18%) in group II developed severe, permanent neurologic sequelae after they initially presented with eye disease. Two of the children in each group are now retarded (IQ score range, 36 to 62). Six of the children in group I who were tested sequentially have had lower IQ scores (mean change from 97 to 74) on repeat tests performed an average of 5.5 years later. Less severe neurologic, intellectual, and audiologic deficits were observed in other children in each group. Treatment of some children may have had a beneficial effect on their outcome.