ADP-induced Platelet Aggregation and Metoprolol Treatment of Myocardial Infarction Patients

ABSTRACT The effect of metoprolol on platelet aggregation was investigated in a group of postmyocardial infarction (MI) patients. The study was double-blind and included 63 subjects; 30 patients were maintained on metoprolol and 33 received placebo treatment. Adenosine diphosphate (ADP)-induced platelet aggregation was carried out in each subject close to 4 weeks after the acute MI. It was demonstrated that metoprolol as compared to placebo did not influence ADP-induced platelet aggregation in the present clinical setting.     

ADP-induced Platelet Aggregation in Young Female Survivors of Acute Myocardial Infarction and Their Female Controls

ABSTRACT Adenosine diphosphate (ADP)-induced platelet aggregation was studied in 35 young female survivors of acute myocardial infarction (AMI) 14–46 (median 30) months after the infarction. The results were compared to those obtained for 35 control females of comparable age. Five different final ADP concentrations (0.2–1.0 μM) were employed, and the object was to assess the slope for the primary wave of aggregation as well as the threshold ADP concentration for secondary aggregation. The results showed that AMI patients and control subjects did not differ with respect to the primary wave of aggregation. However, secondary platelet aggregation was recorded to a significantly higher extent (p<0.02) in AMI patients than in their controls. The results therefore support the concept that enhanced platelet reactivity is present in patients with documented ischemic heart disease.     

Control of the Amount of Free Molecular Iodine in Iodine Germicides

Horseradish peroxidase has been used to generate iodine compositions that comprised principally free molecular iodine. The concentration of free molecular iodine in these enzyme-based compositions ranged from 44 to 63% of the thiosulphate titratable iodine; this is substantially higher than the corresponding value for the povidoneiodine preparation betadine. The biocidal efficacy of these compositions was proportional to the concentration of free molecular iodine. Iodine compositions with relatively low total iodine concentrations but high levels of free molecular iodine (20–175 ppm) killed Staphylococcus aureus and spores of Bacillus subtilis more rapidly than betadine. The effects of normal saline and these enzyme-based iodine compositions on the rate of epidermal regeneration in superficial swine wounds were comparable. These results suggest that an effective germicide containing a high level of molecular iodine need not be irritating or toxic.     

EFFECT OF HALOTHANE ON LYMPH FLOW

The thoracic lymph duct was cannulated at the root of the neckin seven anaesthetized, artificially ventilated dogs. The meancontrol lymph flow was 1.51 ml kg^–1 h^–1 (SD±0.35).The administration of 1% halothane caused a 59% decrease inmean lymph flow (to 0.62 ml kg^–1 h^–1) within 20min, which returned to control values 30 min after the discontinuationof the administration of halothane.     

An Experimental Method for Thermal Control of Heart Rate: Work in Progress

Evaluation of the postoperative course of coronary artery bypass patients shows that a number develop supraventricular arrhythmias that may be responsive to sino-atrial node (SAN) cooling. The sinus rate can be controlled within a clinically useful range with topical cooling probes (thermodes). The data on the variations of heart rate caused by modest nodal hypothermia indicate that a non-pharmacologic clinical system for control of supraventricular tachyarrhythmias is feasible. Prototype thermodes suitable for SAN implantation have been developed.     

Squamous Cell Carcinoma of the Stomach

Squamous cell carcinoma of the stomach is a rare, unusual lesion which tends to occur at a somewhat earlier age than adenocarcinoma. Grossly and radiologically the tumor is indistinguishable from adenocarcinoma and may involve any portion of the stomach. Although the pathogenesis of this lesion remains unclear, most authors favor the "metaplastic theory" for the development of the tumor. In this case it is felt that the tumor probably arose from gastric squamous mucosa present congenitally in the lesser curvature.     

Porphyria cutanea tarda (PCT) in a patient with chronic renal failure on haemodialysis

Porphyria cutanea tarda, diagnosed by reduced levels of red cell uroporphyrin decarboxylase and raised plasma porphyrins, developed in a patient with chronic renal failure due to polycystic kidneys, treated with haemodialysis, who had normal total urinary and faecal porphyrins. Haemodialysis did not alter plasma porphyrin levels and we deduced that most of the plasma porphyrins were circulating in high molecular weight protein complexes.     

Use of Adenosine to Identify Patients at Risk for Recurrence of Accessory Pathway Conduction After Initially Successful Radiofrequency Catheter Ablation

Objectives: The use of adenosine after radiofrequency catheter ablation of accessory pathways was prospectively studied to determine its utility for identifying patients at risk for recurrence of accessory pathway conduction and to guide therapy that might reduce late recurrence in this group. Background: Accessory pathway conduction recursin 5%–12% of patients following initially "successful" radiofrequency catheter ablation. Adenosine may facilitate conduction over accessory pathways that have been modified by radiofrequency delivery, thus identifying patients at risk for recurrence. Methods: Radiofrequency catheter ablation was performed in 109 patients. Prior to ablation, 12–18 mg of adenosine was administered. After ablation, when all evidence of accessory pathway conduction remained absent for at least 30 minutes, adenosine 12–18 mg was again administered. Results: Adenosine given prior to radiofrequency catheter ablation did not block accessory pathway conduction in any patient. Adenosine given after elimination of accessory pathway conduction induced complete atrioventricular and ventriculoatrial block in 95 patients; 11 (11.6%) subsequently had recurrence of accessory pathway function. Accessory pathway conduction was unmasked by adenosine in 12 patients (11.2%). After further deliveries of radiofrequency energy, 7 of these 12 patients subsequently demonstrated adenosine induced atrioventricular and ventriculoatrial block; 1 of these 7 patients experienced recurrence of accessory pathway conduction. The remaining 5 patients demonstrated persistent accessory pathway conduction only with adenosine; all experienced clinical recurrence of accessory pathway function. Conclusion: The use of adenosine after presumed successful radiofrequency catheter ablation may reveal persistent accessory pathway conduction. Elimination of this latent accessory pathway conduction reduces the risk for recurrence.