A dom inant tenet in physio logy for m .ore t han half a century h as been the principle of homeostasis. The term was coined by W. B. Cannon (2) to describe the observation that physiological systems normally operate to reduce variability and to maintain a constancy of internal function. Accordingly, one might expect most any physiological variable, including heart rate, to return to its normal...

We studied the refractoriness of Purkinje fibers with the intent of localizing critical sites of block of premature impulses. To preserve the ventricular conducting system (VCS) nearly intact in vitro, we used a modification of the Elizari preparation. This was superfused with a physiologic salt solution. Action potential durations increased progressively from the His bundle to the distal Purki...

This study concerns two cases of chronic 2 degrees atrioventricular (A-V) block with left bundle branch block (LBBB). Pathological studies included serial section of the conduction systems. Case 1 had type I 2 degrees block with LBBB. Electrophysiological studies revealed type I 2 degrees block proximal to the His bundle recording site and a prolonged H-V interval (60 msec). Pathologically ther...

the anterior cruciate ligament (acl) is composed of two bundles, which work together to provide both antero-posterior and rotatory stability of the knee. understanding the anatomy and function of the acl plays a key role in management of patients with acl injury. anatomic acl reconstruction aims to restore the function of the native acl. femoral and tibial tunnels should be placed in their anat...

To date the electrophysiological mechanism responsible for aberrant intraventricular conduction of critically timed premature supraventricular impulses has not been documented. Microelectrode techniques were used to measure in vitro action potential and refractory period durations of the canine proximal right and left bundle branches equidistant from the distal bundle of His. Both measurements ...

BACKGROUND Pressure ulcer prevention is a critical patient safety indicator for acute care hospitals. An innovative pressure ulcer prevention care bundle targeting patient participation in their care was recently tested in a cluster randomised trial in eight Australian hospitals. Understanding nurses' perspectives of such an intervention is imperative when interpreting results and translating e...

His bundle electrograms were recorded and A-V junction pacing was achieved in 30 patients by a pervenous electrode catheter technic. His bundle pacing was achieved in 26, and A-V node pacing in five patients. Conduction time from atrium to the His bundle (A-H time) and His bundle to ventricular activation (H-V time) were measured. During His bundle pacing, the pacing impulse to ventricular acti...

The alterations in ventricular excitation resulting from production of discrete punctate electrocautery lesions in the canine bundle of His were studied. Electrocardiographs changes were correlated with lesions identified anatomically by microscopic examination of the atrioventricular bundle. Although partial or complete atrioventricular block developed from lesions at several levels of the atr...

BACKGROUND Posterior Cruciate Ligament (PCL) ruptures are common sports injuries. One of the key controversies in PCL reconstruction is whether double-bundle reconstruction provides biomechanical and clinical outcomes superior to single-bundle reconstruction. METHODS We performed a comprehensive search in multiple databases to evaluate the advantages of single-bundle or double bundle reconstr...