Radiofrequency ablation is an established method for treatment of type I atrial flutter. The assessment of creation of complete bidirectional isthmus block following linear ablation of the isthmus is an integral part of ablation procedure. Conventionally, bidirectional isthmus block is tested by pacing on either side of ablation line and looking for reversal of activation sequence in the right atrium. We looked at the feasibility of recording double potentials, separated by an isoelectric interval along the ablation line as an alternative method to demonstrate bidirectional isthmus block. An attempt was made to record the double potentials following linear ablation of the cavotricuspid isthmus. Following ablation, bidirectional isthmus block was also tested by pacing from the coronary sinus os and the low-lateral right atrium. We could demonstrate double potentials in 9 of the 11 patients in whom we attempted to record them following linear ablation of flutter. The presence of bidirectional block by pacing from coronary sinus os and low lateral right atrium could be demonstrated in 10 (91%) patients. Thus, double atrial potentials, separated by an isoelectric interval can be demonstrated following ablation of atrial flutter. Double potentials, if demonstrable on coronary sinus os and low lateral right atrium pacing, could serve as an alternative marker of isthmus block.

Action Potentials↗

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Overcrowding: a behavioral perspective.

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Asia↗

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[The use of geographic indicators of mortality for planning health services: the experience in Great Britain].

The computation of standardized mortality ratio (SMR) is carried out at various geographical levels: by regional health authorities, district health authorities, and wards. Mortality disparities are correlated to differential living conditions. Areas showing a higher SMR are likely to be those with an under-privileged population. The relationship may be expressed graphically. On the basis of these findings, the Health Education Authority decided to implement policies aimed at: (i) decreasing cardiovascular mortality by 15 percent; (ii) decreasing the gap between under-privileged and "rich" districts by 15 percent. These objectives are expressed graphically in Fig. 4: line A must be replaced by line B. The conclusion reached is that the decrease in the mortality rate cannot be achieved by a single action on the part of health authorities, as the task of improving living conditions or modifying individual behavior patterns is beyond their reach. Nevertheless, these challenges can and should be overcome.

Cause of Death↗

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Some properties of acid and alkaline phosphomonoesterases of chicken spermatozoa.

Alkaline (ALP) and acid (ACP) phosphomonoesterases present in the cell-free extracts of the Triton x-100 treated freshly ejaculated chicken spermatozoa were studied of some of their physico-chemical properties. Alkaline phosphomonoesterase was found to have the optimal specific activity at pH 7.6 in 100 mM Tris-HCl buffer and was temperature-dependent and reached its peak at 70 degrees C. This activity was stimulated by Mn++, Co++, Mg++ and Fe++ ions and inhibited by Cu++, Hg++, Ca++, EDTA and dithiothreitol. Acid phosphomonoesterase, in similar conditions of assay procedure, had optimal activity at pH 5.0 at 60 degrees C after 30 min incubation. It was stimulated by Co++, Mg++, EDTA and dithiothereitol, but other divalent ions and N-ethylmaleimide inhibited the activity. These data suggest that these enzymes of chicken spermatozoa are some how different in character from those of mammalian ones.

Animals↗