Beyond the Coronary Angiogram: Further Evaluation of the Coronary Vasculature and Endothelial Function

Coronary artery disease is a progressive and diffuse process. The focus in the past decade was on the late stage of coronary atherosclerosis, with efforts being devoted to the development of thrombolytic drugs and sophisticated interventional devices. However, in spite of the success in decreasing morbidity and mortality from coronary atherosclerosis, the disease process continues. Early diagnosis and treatment of patients with nonobstructive coronary artery disease, may prevent the development of unstable angina and myocardial infarction. It has become apparent that the endothelium is the primary target and/or participant in the early stages of coronary atherosclerosis. The endothelium is as an active paracrine organ capable of regulating coronary vascular tone as well as the atherosclerotic and restenosis process by releasing vasorelaxing factors with antiproliferative activity and vasoconstricting and growth factors. During the evolution of coronary atherosclerosis endothelial dysfunction occurs, which is characterized by attenuated release and activity of endothelium derived vasorelaxing factors and enhanced release of vasoconstricting factors. The goal of cardiology is to develop diagnostic methods and treatment for these patients who present to us with cardiac symptoms and nonobstructive coronary artery disease. This article will review the current knowledge of endothelial function as it applies to coronary circulation and describe a clinical approach to the patient with suspected coronary disease and a normal coronary angiogram. (J Interven Cardiol 1996;9:153–161)     

Teratologic Evaluation of Inhaled Propylene Glycol Monomethyl Ether in Rats and Rabbits

Teratologic Evaluation of Inhaled Propylene Glycol MonomethylEther in Rats and Rabbits. HANLEY, T. R. JR., CALHOUN, L. L.,YANO, B. L, AND RAO, K. S. (1984). Fundam. Appl. Toxicol. 4,784–794. Pregnant Fischer 344 rats and New Zealand Whiterabbits were exposed via inhalation to 0, 500, 1500, or 3000ppm of propylene glycol raonomethji ether (PGME) for 6 hr/dayon Days 6 through 15 (rats) or 6 through 18 (rabbits) of gestation.Initial exposure to 3000 ppm of PGME produced signs of mildcentral nervous system depression which were more pronouncedand of a longer duration in rats than in rabbits. Postexposurerecovery was rapid and accomodation to the test atmosphere developedfollowing subsequent exposures. Rats and rabbits exposed to3000 ppm had decreased weight gains over the exposure periodand rats had decreased food consumption during the first 3 daysof exposure. Fetal examination revealed no embryotoxic or teratogenkeffects among rats or rabbits in any exposure group. Slightfetotoxicity among rats, in the form of delayed sternebral ossification,was observed at 3000 ppm. Thus, it was concluded that PGME wasnot teratogenic at exposure levels up to 3000 ppm.     

Nasal mask positive pressure ventilation in paediatric patients with type II respiratory failure

We report our experience with nasal mask ventilation in children and adolescents with type II respiratory failure admitted to the paediatric intensive care unit (PICU) over an 18-month period. Seven patients were treated with nasal mask ventilation during part of their PICU stay. All showed significant improvement in arterial pH, Pa_CO2, and Pa_O2/FiO₂ from presentation to discharge, although at discharge Pa_CO2 and Pa_O2/FiO₂ fell outside of the normal range. Complications occurred in four patients. When compared to 11 patients with type II respiratory failure not treated with nasal mask ventilation, the nasal mask ventilation group had a similar PICU length of stay and incidence of complications. We conclude that nasal mask ventilation may be useful in maintaining near normal alveolar ventilation in selected children with type II respiratory failure and that a prospective study of this technique is indicated.     

The effect of coronary artery bypass surgery on ventricular arrhythmias

The effect of coronary artery bypass surgery (CAB) on ventriculararrhythmias (VA) was studied in a prospective investigationinvolving 32 patients (mean age 54 years) who underwent CABbecause of severe stable angina pectoris. Prior to CAB as wellas 12 months later each patient was subjected to the followinginvestigational programme: resting ECG, exercise ECG, 24-h ECG,selective coronary arteriography, ventriculography and cardiaccatheterization. Exercise ECG showed VA in only three patients.The prevalence of VA during 24-h ECG was 56 and 66% on the twooccasions (NS), while complicated VA (multiform, repetitive,R on T) was seen in 18 and 28%, respectively (NS). The persistence(number of 6-h periods showing VA) was 33 and 47% with regardto any VA (P<0.05), while complicated VA occurred in 13 and15% of the 6-h periods (NS). Except for an increase in dp/dt_max/Pat the postoperative measurement (P<0.05), no significantchange in the performance of the left ventricle was seen afterCAB though the graft patency was 77%. It is concluded that inpatients with ‘medically intractable’ stable anginapectoris, CAB does not effect the occurrence of VA to any greatextent — probably because left ventricular function isunchanged one year after as compared with that prior to CAB.     

THE RESPIRATORY EFFECTS OF A POTENT ANALGESIC (GPA 2087) IN MAN

The respiratory depressant effects of a potent analgesic (GPA2087) were compared with morphine in a randomized double-blindcross-over study in human volunteers. Using a rebreathing technique,carbon dioxide response curves were plotted automatically witha special-purpose analog computer. The respiratory depressantrelative potency of GPA 2087 to morphine was found to be 1.21with lower and upper 95 per cent confidence limits of 0.88 and2.04. Our best estimate based on the displacement of the respiratoryresponse curve is that GPA 2087 8 mg is the equivalent of morphine10 mg in our population of volunteers. ^*Geigy Pharmaceuticals, Ardsley, New York, U.S.A. ^*Present address: Salisbury General Infirmary, Odstock Branch,Salisbury, Wiltshire, England.