ABSTRACT
A patient with episodes of palpitation in whom the electrocardiogram showed a right bundle branch (RBBB) configuration and right axis deviation underwent electrophysiologic study and radiofrequency ablation. Left ventricular endocardial mapping during ventricular tachycardia (VT) identified the earliest ventricular activation in the anterolateral wall of the left ventricle. The fused Purkinje potential was recorded at that site, and preceded the QRS complex by 47 mseg, with pace mapping showing an optimal match between the paced rhythm and the clinical VT. The stimulus to QRS time was equal to the Purkinje potential-QRS time. Several radiofrequency lesions were applied in this region, one of them resulted with termination of the tachycardia. Following delivery of this lesion the ventricular tachycardia couldn't be induced either at baseline or during isoproterenol infusion. During VT, atrial fibrillation and atrial flutter were observed, cardioversion was performed reverting to sinus rhythm.
Subject(s)
Atrial Flutter/complications , Tachycardia, Ventricular/complications , Ventricular Fibrillation/complications , Atrial Flutter/diagnosis , Bundle-Branch Block/complications , Catheter Ablation , Electric Countershock , Electrocardiography , Humans , Male , Middle Aged , Purkinje Fibers/physiology , Tachycardia, Ventricular/diagnosis , Ventricular Fibrillation/diagnosis , Ventricular Function, LeftABSTRACT
The role of pressure reduction in the formation and growth of bubbles is universally recognized and its significance in decompression theory has been accepted. Yet the allowable limits of pressure reduction for man and animal are uncertain. This study sought to evaluate the pressure-reduction limits for rats following steady-state exposures at pressures greater than 1 atm. To define the relationship, 350 albino rats were exposed to 1 of 12 specified pressure levels between 6 and 60 ATA and then abruptly decompressed to a preselected reduced pressure level for observation. The pressure-reduction levels were selected to determine for each saturation-exposure level an ED-50 (i.e. the effective dose that will produce decompression sickness in 50% of the animals). The results demonstrate three consistent findings: (1) there is a linear relationship (r = .99) between the magnitude of a safe pressure reduction and the saturation exposures between 6 and 43 ATA; (2) at pressures greater than 43 ATA, there is a qualitative change in the decompression sickness symptoms and a reduction in the precision of the mathematical relationship (r = .44); and (3) the magnitude of the pressure change required to increase the incidence of decompression sickness from 10% to 90% is directly related to the magnitude of the exposure pressure. The implications of these results for deep operational diving are discussed.
