Implantation of the Automatic Implantable Cardioverter Defibrillator

Since February 1980 the automatic implantable cardioverter defibrillator has been implanted in over 1,500 patients. Sudden death rates have been reduced to 2%-4% annually. This report reviews the implantation techniques, their indications, and our clinical experience in 200 patients.     

Closed Chest Radiofrequency Ablation of the Sinoatrial Node in Dogs

Transcatheter ablation of the sinoatrial node with radiofrequency energy (0.6 MHZ, 2.5-5 watts) was performed in 10 dogs under fluoroscopic monitoring and autonomic blockade. Sinus function was previously studied in terms of cycle length, recovery time and atrial activation pattern by catheter mapping. Several discharges (8-22) were applied for variable periods of time (maximum 1 minute). Sinus tachycardia and/or sinus arrest during ablation confirmed correct catheter position. Sinus rhythm was abolished in eight dogs. The ectopic rhythm was atrial in six and AV nodal in two dogs. Ectopic atrial cycle length and recovery time were longer than the baseline sinus values: 724 +/- 321 versus 509 +/- 147, P less than 0.05; 1103 +/- 775 versus 618 +/- 151, P less than 0.05 (values in msec). The study was repeated 10-14 days later in six dogs; three maintained the same atrial rhythm, one persisted in sinus rhythm, and one dog changed from atrial to sinus rhythm, whereas another changed from sinus to atrial rhythm. Gross findings revealed transmural lesions in all dogs, without perforation. Histology in chronic dogs showed sinus cell necrosis and its replacement by granulation tissue. In conclusion: sinus function may be abolished by closed chest radiofrequency ablation.     

A peptide of nine amino acid residues from α-sarcin cytotoxin is a membrane-perturbing structure

A water-soluble synthetic peptide with only nine amino acid residues, comprising the 131–139 sequence region of the cytotoxic protein α-sarcin (secreted by the mold Aspergillus giganteus), interacts with large unilamellar vesicles composed of acid phospholipids. It promotes lipid mixing between bilayers and leakage of vesicle aqueous contents, and it also abolishes the phospholipid phase transition. Other larger peptides containing such an amino acid sequence also produce these effects. These peptides acquire α-helical conformation in the presence of trifluoroethanol, but display β-strand conformation in the presence of sodium dodecyl sulfate. The interaction of these peptides with the lipid vesicles also results in β-structure. The obtained data are discussed in terms of the involvement of the 131–139 stretch of α-sarcin in its interaction with lipid membranes.     

What's Happened to the Cannabis Debate?

The public debate on cannabis is showing signs of extinction. Little has been heard about this drug from political authorities in recent years, and the scientific community appears to be losing interest itself. Social complacency, the emergence of other drug habits which are perceived as being more threatening, and the rather limited progress made in answering some major cannabis research questions could explain this course of events. History shows that scientific work on cannabis is usually prompted by apolitical need to respond to a high level of social concern over this drug. When such social pressure diminishes, scientific interest tends to fade away. This paper warns against the repetition of previous historical episodes and gives an account of the many research issues that remain unanswered at this point.     

Declining prevalence of injection as main route of administration among heroin users treated in Spain, 1991-1993

The objetive of this study was to analyse the temporal and geographictrends and the factors associated with the prevalence of heroininjection (HI) in persons treated for the first time for heroinabuse/dependence in Spain in 1991–1993. The prevalenceof HI was studied in 54,132 admissions to treatment reportedto the State Information System on Drug Abuse. The factors associatedwith HI prevalence were studied by stratified analysis and logisticregression. Regions with similar prevalences were grouped togetherbased on correspondence analysis. The HI prevalence declinedprogressively by year (50% in 1991, 43% in 1992 and 38% in 1993).The regions were grouped into 3 geographic areas, with risingprevalences in the southwest-northeast. Region was the factormost strongly asociated with HI, with an OR of 6.17 in the highprevalence group as compared with the low prevalence group.A declining trend of HI was seen with the more recent year offirst use (OR of 0.15 for those beginning use in the years 1991–1993as compared with those who began before 1982), later age atfirst use and increasing years of use. Male sex and cocaineuse were associated with higher HI. Chasing is progressivelyreplacing injection as a route of heroin administration becausenew users primarily use this route and probably because themost common transition is from injecting to chasing. The impactof the HIV epidemic and control programmes does not sufficientlyexplain this phenomenon. The main explanatory factors couldbe regional differences in the subculture of drug use or inthe heroin market.     

Are Double Potentials Markers of a Specific Zone of the Atrioventricular Junction in the Isolated Rabbit Heart?

A study is made of the characteristics of the atrial potentials recorded in the Koch triangle and its proximity, their variations on modifying the site of cardiac pacing, and their usefulness as markers of a distinct zone of the AV junction. In 12 isolated and perfused rabbit heart preparations an analysis was made of the endocardial atrial electrograms recorded with a multiple electrode positioned in the AV junction. The electrograms were obtained during spontaneous rhythm and on pacing at the crista terminalis (CT), interatrial septum (IAS), left atrium, and right ventricle. Double potentials were frequently obtained. On pacing at the CT, high-low double potentials (DP [H-L]) were more frequent (P < 0.05) in the low CT (11%± 4% of the electrodes) and posterior zone of the Koch triangle (6%± 5%), than in the IAS (1 %± 2%) and anterior zone of the Koch triangle (2%± 3%). A similar tendency was observed either on pacing at the left atrium or during spontaneous rhythm. During pacing at the IAS the percentages of low-high double potentials (DP[L-H]) were significantly higher (P < 0.05) in the low CT (7%± 6%). DP (H-L) were of low sensitivity in indicating a given zone; maximum sensitivity was 61 % in the low CT when pacing at the CT. DP (L-H) proved even less seusitive in indicating a given zone, though their specificity was greater in the low CT (91%) during pacing at the IAS. The specific zones in which the highest percentages of DP (H-L) or DP (L-H) are obtained depend on the site of cardiac pacing. On pacing at the IAS. DP (L-H) are more specific of the low CT. During pacing at both the CT and at the IAS. DP (H-L) sensitivity in indicating a given zone is low.     

UTILITY OF BONE MARROW AND LIVER BIOPSIES FOR STAGING CUTANEOUS T-CELL LYMPHOMA

Background. The wide use of staging procedures, looking for visceral involvement in patients with cutaneous T-cell lymphoma (CTCL), is controversial, especially in the early stages. In this study, we analyzed the results of bone marrow biopsy and laparoscopy with liver biopsy in a series of 43 patients with CTCL. Methods. Clinicopathologic stages were established by a modification of the TNM system proposed in 1979. Results of staging procedures were correlated with blood cell counts and laboratory tests. The usefulness of the staging procedures was analyzed particularly in patients without clinical or biologic evidence of extracutaneous disease. Results. The patient's median age was 66 years; 35 patients were men and eight women. The clinicopathologic stages were as follows: T1: 3 cases; T2: 15; T3: 14; T4: 11; NO: 15; N1: 28; MO: 38; Ml: 5; BO: 37; and B1: 6 cases. Internal lymph node disease, diagnosed by lymphangiography and/or abdominal scanning, was demonstrated in 37% of patients. Bone marrow infiltration was seen in 12% of patients and was the only form of visceral involvement. All liver biopsies were negative. Serum lactate dehydrogenase (LDH) levels were raised in patients with lymph node disease; it was the only laboratory test that correlated with extracutaneous involvement. Staging procedures changed three of the nine patients with a clinical T1-T2N0M0B0 stage (33%) to a more advanced stage. The abdominal lymph node evaluation allowed a reclassification from NO to N1 in two of nine cases (22%); one of the remaining cases was reclassified from MO to M1 on the basis of bone marrow biopsy results. Conclusions. Our results indicate that bone marrow biopsy is a useful investigational procedure for determining extracutaneous disease in CTCL. Peritoneoscopy with liver biopsy rarely is informative; however, as our study does not include a very large number of patients, these preliminary conclusions must be confirmed in the future by including more cases.