Lead Extraction in Young Patients With and Without Congenital Heart Disease Using the Subclavian Approach

Pacemaker lead removal using interlocking stylets and dilator sheaths has greatly reduced the need for major surgical intervention when lead extraction is required. Previous reports have shown the utility of this method in older patients, most of whom have anatomically normal hearts. The purpose of this study is to report the results of this technique in young patients with and with-out congenital heart disease. There were 13 patients (M:F = 7:6) aged 9–26 years (median 13). Congenital heart disease was present in 8 of 13 patients. A total of 17 leads required removal; they had been implanted for 54 ± 24 months (range 19–94). Leads were removed from the left subclavian vein (13) or right subclavian vein (4) only. Seventeen of 18 leads were completely removed and one partially retained in the left subclavian vein. New leads were implanted from the same vein in 11 of 13 patients. Interlocking stylets and metal or flexible dilator sheaths were used in all cases except two. There was one surgical complication: a late wound dehiscence, which was easily managed. No patient required a transfusion, and there was no structural damage noted in any patient on the postoperative echocardiogram. We conclude that lead removal using interlocking stylets and dilator sheaths from the subclavian approach is an effective technique that can be used in young patients, including those with congenital heart disease.     

Fusion or Confusion on Holter Recording

Holter recording of a patient with an implanted dual chamber rate responsive pacemaker revealed an electrocardiogram, where ventricular depolarization seemed to be initiated by the atrial stimulus. In a second patient with a VVI pacemaker, Holter recording showed delay of the pacemaker impulse that was registered after the onset of ventricular depolarization. Misalignment in one of the recorder heads of the display system was responsible for this phenomenon, which in case of dual chamber pacing could have been easily misinterpreted as pacemaker malfunction.     

Endothelial cell dysfunction in homocystinuria

Abstract. This report describes the isolation and culture of venous endothelial cells from the umbilical cord of an obligate heterozygote for homocystinuria. The effect of different sulphur-containing amino acids on the viability and function of these cells was studied and compared with cultured normal endothelial cells. When endothelial cells were cultured in the presence of methionine (10 mmol/l) or homocystine (10 mmol/l), differences occurred between the viability and function of the heterozygote and normal cells in terms of ⁵¹Cr release and ability to prevent platelet adherence. The Cr release corrected for spontaneous release increases for the heterozygote cells after incubation for 21 h in the presence of methionine to 81.3% (control cells, range: 0–23.3%, n = 5) and in the presence of homocystine to 141% (control cells, range: 13.5–55.2%, n = 5). The total number of platelets that adhere to confluent monolayers increases for heterozygote cells cultured in the presence of methionine to 0.98 ± 10⁷ platelets cm^-2 (normal cells, range: 0.56–0.72 ± 10⁷ platelets cm^-2) and in the presence of homocystine to 1.41 ± 10⁷ platelets cm^-2 (normal cells, range: 0.94–1±06 ± 10⁷ platelets cm^-2). Both normal and control cells were sensitive to homocysteine. This study indicates for the first time what vascular endothelial cells, derived from an obligate heterozygote, are (partly) deficient in cysthathionine synthase and are more susceptible to methionine- and homocystine-mediated injury than normal endothelial cells. Consequently, in homocystinuria, due to dysfunction of the endothelial cells, toxic sulphur-containing amino acids may accumulate in these cells, causing injury of these cells.     

Efficacy and Safety of Rate Responsive Pacing in Patients with Coronary Artery Disease and Angina Pectoris

The present study included 17 patients with angina pectoris and coronary artery disease in whom a rate responsive ventricular pacemaker (Medtronic Activitrax) had been implanted. All patients had an exclusively paced rhythm. Single blinded, random, cross-over treadmill tests in the rate responsive pacing mode (VVIR) and in the fixed-rate demand mode (VVI) were performed, with an interval of 4-6 weeks. Mean exercise duration increased by 25% during VVIR pacing. Maximal heart rate increased significantly during VVIR compared to VVI pacing (VVI = 74 +/- 2 bpm, VVIR = 116 +/- 8 bpm, P less than 0.001) as did the rate-pressure product (VVI = 10.850 +/- 1,124, VVIR = 16.628 +/- 2,110, P less than 0.001). Despite improved performance, the number of anginal attacks per week and the nitroglycerin consumption did not show a significant difference between the two pacing modes. It is concluded that rate responsive pacing is beneficial and safe in patients with angina pectoris and coronary artery disease.     

Effects of a standardized wheat bran preparation on biliary lipid composition and bile acid metabolism in young healthy males

The effects of adding bran to the normal diet on biliary lipid composition and bile acid metabolism in a group of young healthy males was studied. A chemically standardized coarse wheat bran product, with serum lipid lowering properties, in a dose of 0.5 kg-1 body weight per day was used. Bran feeding for 4 or 8 weeks did not change biliary lipid and biliary bile acid composition. Faecal bile acid and neutral sterol composition was similar before and after 8 weeks of bran. Bile acid kinetics, measured by double isotope dilution after simultaneous injection of [3H]cholic acid and [14C]deoxycholic acid, showed only minor differences before and during bran ingestion. The most surprising finding was an increase in 7 alpha-dehydroxylation fraction (input of deoxycholic acid divided by synthesis of cholic acid) in six out of seven subjects after 4 weeks of brain and in all four subjects after 8 weeks of bran. In conclusion, the bran product we used is not effective in lowering the biliary cholesterol saturation in healthy young males. Nor does it reduce deoxycholate input in our subjects even after 8 weeks of bran.     

Reflex Cardiac Asystole

In this report we present the case of a patient with recurrent syucopal episodes. During one of the attacks the patient was monitoring by telemetry and the ECC lead showed asvstole for more than 7 seconds. As in cases of the carhlinhibitory type of hypersenstive carolid sinus svndrome [HCSS]. asvstole may represent suppression of the sinus node or suppression of both sinus and atioventricular [AV] node. Unfortunately, in contrast to HCSS, there is no maneuver that can reproducibly induce episodes of asystole. Consequentlty, very little is known about the occurrence of AV block in the presence of sinus arrest. In the patient described in this report. We were able to demonstrate that suppression of sinus and AV nodes occured simultaneously. This is interesting to note that in this type of syneope data from noninvasive and invasive techniques in assessing sinus nodal and AV nodal conduction may note be conclusive. In the group of patients with this type of syncope, permanent artial demand pacing is constraindicated.     

Intraindividual Reproducibility of Heart Rate Variability

Heart rate variability was determined from three consecutive Holter recordings performed on days 1, 7, and 28 in 17 normal subjects, in 13 patients with angiographically normal coronary arteries, and in 9 patients with remote myocardial infarctions. Group data of several time and frequency domain measures of heart rate variability were highly reproducible (correlation coefficients 0.629–0.894). However, some individuals exhibited considerably larger day-to-day variations in heart rate variability. Single heart rate indices differed by up to 50% between two Holter recordings. Such potential differences must be considered when repeated heart rate variability determinations are used to assess changes in neurocardiac reflex regulation or effects of therapeutic interventions.