Lack of HIV transmission in the practice of a dentist with AIDS.

OBJECTIVE: To determine whether dentist-to-patient or patient-to-patient transmission of human immunodeficiency virus (HIV) occurred in the practice of a dentist who had the acquired immunodeficiency syndrome (AIDS). DESIGN: Retrospective epidemiologic investigation supported by molecular virology studies. SETTING: The practice of a dentist with AIDS in an area with a high AIDS prevalence. PARTICIPANTS: A dentist with AIDS, his former employees, and his former patients, including 28 patients with HIV infection. MEASUREMENTS: Identification of potential risks for acquisition of HIV infection, genetic relatedness among HIV strains, and infection-control practices. RESULTS: A dentist with known behavioral risks for HIV infection, who was practicing in an area of Miami, Florida, that had a high rate of reported AIDS cases, disclosed that he frequently did invasive procedures and did not always follow recommended infection-control procedures. Of 6474 patients who had records of receiving care from the dentist during his last 5 years of practice, 1279 (19.8%) were known to have been tested for HIV infection and 24 of those (1.9%) were seropositive. Four other patients with HIV infection were identified through additional case-finding activities. Of these 28 patients with HIV infection, all but 4 had potential behavioral risk factors for infection. Phylogenetic tree analysis of HIV genetic sequences from the dentist and 24 of the patients with HIV infection showed an absence of strong bootstrap support for any grouping and therefore did not indicate that the virus strains were linked. CONCLUSIONS: Despite identifying numerous patients with HIV infection, we found no evidence of dentist-to-patient or patient-to-patient transmission of HIV during dental care. Our findings are consistent with those of all previous studies in this area, with the exception of one that did identify such transmission.

Arrhythmias in the coronary-care unit. VI. Physiologic bases for the use of antiarrhythmic drugs.

Classification of antiarrhythmic drugs based on their electrophysiologic and hemodynamic properties coupled with an understanding of the transmembrane action potential of the cardiac cell (see the first of this series of six vignettes) help in the appropriate choice of therapy in a given clinical setting.

Arrhythmias in the coronary-care unit. V. Physiologic bases of paroxysmal bradycardia-dependent bundle branch block.

Bradycardia-dependent bundle branch block can occur during acute cardiac ischemia or infarction. Basic cellular electrophysiology helps in understanding the mechanisms involved. A review of the previous four vignettes of this series will be helpful in studying this vignette.

Arrhythmias in the coronary-care unit. IV. Physiologic bases of paroxysmal tachycardia-dependent bundle branch block.

Paroxysmal BBB may be either tachycardia-dependent which is referred to as "phase 3 block" or bradycardia-dependent, referred to as "phase 4 block." Tachycardia-dependent BBB is related to prolonged recovery. Bradycardia-dependent BBB is related to hypopolarization and SDD. These fundamental electrophysiological properties aid in understanding of transient BBB occurring during an acute MI.

Arrhythmias in the coronary-care unit. III. Physiologic bases of paroxysmal tachycardia-dependent A-V block.

This vignette illustrates the application of electrophysiological principles to the clinical problems of acute trifascicular A-V block occurring during an acute MI. Paroxysmal trifascicular A-V block that occurs transiently during an acute MI can be explained electrophysiologically as being due to tachycardia-dependent or bradycardia-dependent A-V block or both. Tachycardia-dependent A-V block also referred to as phase 3 A-V block is a term used when a premature beat occurring during repolarization of the preceeding beat causes conduction failure. Bradycardia-dependent A-V block or phase 4 block is used to explain the slowing of conduction or block after a longer diastolic interval. Physicians and nurses can improve their care of the critically ill cardiac patient through a better understanding of pathophysiology.

Arrhythmias in the coronary-care unit. II. Physiologic bases of paroxysmal bradycardia-dependent A-V block.

Bradycardia-dependent A-V block during acute cardiac ischemia or injury is best explained by applying knowledge of basic cellular electrophysiology. Spontaneous diastolic depolarization during phase 4, plus a reduction in the magnitude of the transmembrane action potential are the pathophysiologic changes responsible for "phase-4 block".