Letter: Effects of marijuana in coronary disease.
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Cannabis↗
Biomedical subjects
C Kanakis
Publications and source records attributed to C Kanakis.
The effects of delta-9-tetrahydrocannabinol (cannabis) on cardiac performance with and without beta blockade.
Systolic time intervals (STI) were measured in ten healthy male volunteers before and after intravenous (i.v.) administration of 25 mug/kg delta-9-tetrahydrocannabinol (delta-9-THC). Mean +/- SEM heart rate increased 32 +/- 7 beats/min, while systolic and diastolic blood pressures were unchanged after delta-9-THC. Total electromechanical systole lengthened 17 +/- 4.2 msec, left ventricular ejection time (LVETc) prolonged 24 +/- 4.0 msec and pre-ejection period (PEP) shortened 17 +/- 5.1 msec after delta-9-THC. All of these changes were significant (P less than 0.01). In nine other subjects who underwent prior beta adrenergic blockade, similar but less marked changes were noted in heart rate, blood pressure, and STI after delta-9-THC. The shortening of PEP after delta-9-THC was only 9 msec (NS) in beta blocked subjects. Thus, delta-9-THC significantly increased heart rate, shortened PEP and prolonged LVETc without any change in afterload. Beta adrenergic blockade prevented significant shortening of PEP and blunted other responses. These findings suggest that delta-9-THC enhanced cardiac performance. Partial inhibition of this effect was achieved with prior beta adrenergic blockade.
Adult↗
Return of normal conduction after paroxysmal heart block. Report of a case with major discordance of electrophysiological and pathological findings.
This report describes a 52-year-old male with paroxysmal heart block as well as left and right bundle branch block, resulting in Stokes-Adams attacks. The patient experienced a return to 1:1 atrioventricular (A-V) conduction with narrow QRS within 48 hours of the attacks and heart block never recurred. Electrophysiological studies three weeks later revealed a narrow QRS, a normal H-V interval (36 msec), 1:1 A-V conduction up to an atrial paced rate of 210 beats/min, and normal refractory periods with atrial extrastimulus techniques (His-Purkinje system refractory periods less than 370 msec). The patient died from a cerebral embolus incurred during diagnostic left heart catheterization two days after electrophysiological studies. Postmortem examination revealed calcific aortic stenosis with calcific impingement upon the pars membranacea resulting in compression of the distal His bundle and marked disruption of the proximal portions of both bundle branches. This report documents a major limitation of electrophysiological studies, this limitation being that these studies may be totally normal on one occasion in a patient with pathologically significant chronic conduction disease, which may become clinically manifest on another occasion.
Adams-Stokes Syndrome↗
Intraosseous pressure in the lumbar spine.
Intraosseus pressure in the lumbar spine is defined as the hydrostatic pressure of venous blood in the trabecular sinusoids of cancellous bone. Measurements of it in the lumbar vertebrae and the inferior vena cava confirm that the intraosseus pressure in the lumbar spine is identical to, and dependent upon, the pressure in the inferior vena cava. With Valsalva maneuver in the decubitus position, the pressure reaches levels of 90 mm Hg in the inferior vena cava and intraosseus space of lumbar spine.
Adult↗