Ischemic damage of the liver. Part II: In vivo investigation of the prevention of the ischemic lesion of the liver

A new model for the study of ischemic liver lesion on rats has been worked out. Pretreatment with allopurinol, dibenzyline, methylprednisolone, glucagon, ATP-MgCl2 and aspartic acid reduced the overall mortality of ischemic liver injury. Administered after the anoxic hepatic lesion only glucagon and aspartic acid had beneficial effect on the survival rate. Under the influence of 30 minutes of normothermal ischemia the DNA synthetizing ability of the liver decreased. Aspartic acid, glucagon and ATP-MgCl2 significantly enhanced the regeneration of the ischemically damaged liver. These procedures might be suitable for donor pretreatment in liver transplantation, as well as for the treatment of other pathological states, causing a normothermal ischemia of the liver.

Intestinal strangulation in germfree and monocontaminated dogs

Earlier studies in the germfree rat demonstrated that the common intestinal bacteria vary greatly in their ability to cause death after intestinal strangulation. Some of these experiments were repeated in adult, germfree and monocontaminated beagles. Neither short closed-loop hemorrhagic nor long closed-loop ischemic strangulation killed the germfree dog. Either procedure rapidly killed the dog with a conventional bacterial flora or a dog monocontaminated with Clostridium perfringens. The dogs monocontaminated with Bacteroides fragilis died after several days, whereas Escherichia coli killed only one of three animals. These experiments demonstrate the usefulness of the germfree dog as a unique research subject, confirm our earlier studies on intestinal strangulation in germfree rats, and further emphasize the differing lethal potentials of the intestinal bacteria in intestinal strangulation.

Non-occlusive acute intestinal vascular failure

The records of 87 patients with vascular intestinal insufficiency leading to gangrene were analysed in retrospect. In 77 patients the cause of the vascular insufficiency could be determined. In 25 per cent no organic obstruction to blood flow was found in the macroscopic intestinal vessels. The patients with non-occlusive intestinal gangrene showed a tendency to be younger and to have associated cardiac infarction more frequently than those with vessel obstructions. Moreover, non-occlusive intestinal gangrene was found more frequently following a period of systemic arterial hypotension. A history of atrial fibrillation and digitalis therapy was present with equal frequency in both groups of patients.

Based on these cases and on current animal experimental data, it is suggested that the bowel gangrene seen in non-occlusive ischaemia is due to short-circuiting of oxygen at the base of the villi in the villous counter-current exchanger. This mechanism becomes much more effective in hypotension owing to reduced velocity of the villous blood flow. The possibility is emphasized that, with a coexisting atherosclerotic narrowing in the mesenteric vascular tree, cardiovascular disturbances which are themselves not enough to alter central arterial pressure, may none the less induce regional hypotension. Such regional hypotension could lead to villous destruction and initiate a vicious circle which ends in generalized gangrene of the bowel.

Surgical treatment of the severely ischaemic leg: I. Survival rates

Over a 10-year period, 411 patients with atherosclerotic major artery disease causing severe ischaemia of the legs were treated by surgery. Their survival rate, assessed by the life table method, was 80 per cent at 1 year and 50 per cent at 5 years. Early and late survival rates were significantly worse in elderly patients, and in patients with extensive gangrene. Late survival rates were significantly worse in diabetics, and in patients with clinical myocardial ischaemia. Patients treated by arterial reconstruction showed a better survival rate than those treated by sympathectomy or amputation, though the latter groups contained more poor risk patients. Survival rates were not influenced by the technique of reconstruction.

Effects of inhibition of adrenal steroidogenesis on compensation of fluid loss and on survivial after limb ischaemia in the rat

In rats injected with a specific inhibitor of adrenal steroidogenesis, 4alpha,5-epoxy-17beta-hydroxy-3-oxo-5alpha-androstane-2alpha-carbonitrile (WIN 24 540), the increase in the concentration of corticosterone in the plasma caused by bilateral hind-limb ischaemia was greatly reduced. The lethality of this injury was increased. Fluid loss into the hind limbs was unaltered but the compensatory movement of fluid into the plasma was imparied. The hyperglycaemia that occurred after the injury was markedly reduced by WIN 24 540, but this was probably unrelated to the poorer compensation of fluid loss as there was no corresponding fall in plasma osmolality. The effects of injecting WIN 24 540 could be completely reversed by the simultaneous injection of corticosterone, so as to restore the rise in its concentration in the plasma. We conclude that the adrenal cortex plays an active part in the early circulatory and metabolic responses to injury, in contrast to its reportedly permissive role in the later catabolic phase.

Effects of pentoxifylline on cerebral ultrastructure of normal and ischemic gerbils

Normal gerbils and those made ischemic for 15 to 60 minutes by bilateral common carotid artery occlusion were studied ultrastructurally after administration of the vasoactive drug pentoxifylline. In both groups, hypertrophy of neuronal mitochondria was found in the hippocampus and cerebral cortex. Planimetry of electron micrographs revealed a statistically significant increase in average mitochondrial size of drug-treated animals compared with untreated ischemic gerbils and normal controls; the treated ischemic group showed the greatest increase. Incubated cortical slices from normal gerbils that were given the drug 5 hours before they were killed showed a significant increase in oxygen consumption compared with controls.

[Treatment of acute cerebral ischaemia with low-molecular dextran: results of a retrospective study (author's transl)]

Between 1968 and 1970, 226 patients with acute cerebral ischaemia were treated with vasodilator drugs. In the subsequent three years (1971 to 1973) 202 patients were instead treated with dextran (Rheomacrodex) infusions. tin the latter period the death-rate was 35%, 19% less than during the preceding period of vasodilator treatment. In the dextran group among patients over 65 years the death-rate was 42%, 21% less than in the vasodilator group of the same age. Dextran treatment caused complete disappearance of neurological signs in 25%, compared with 7.5% in the vasodilator group. Dividing patients into those with normal blood pressure, hypertension and diabetes gave corresponding differences among the two groups. The death-rate during the period of dextran treatment was significantly less in all the sub-groups than in the vasodilator years. The results of this retrospective study provide important pointers to the effectiveness of dextran infusion in the treatment of acute cerebral ischaemia.

An index of healing in below-knee amputation: leg blood pressure by Doppler ultrasound

Preoperative Doppler ultrasonic assessment of below-knee (BK) arterial signals and systolic blood pressures was performed on 50 patients undergoing 53 BK amputations for advanced ischemia. No patient was excluded from initial BK amputation unless gangrene at that level or severe joint contracture was present. Failure of healing of the BK amputation occurred in all five limbs with an undetectable Doppler arterial signal (and thus pressure) below the knee. Failure of amputation occurred in four of 16 limbs with detectable arterial signals and BK pressures less than 70 mm. Hg. Healing occurred in all 32 limbs with BK pressures greater than 70 mm. Hg. The differences in healing between these three groups are highly significant (p less than 0.005). This study suggests that Doppler ultrasonic assessment of BK arterial signals and pressures may be a simple hemodynamic correlate of healing of a BK amputation. Absence of a detectable arterial signal below the knee may be an indication for initial above-knee (AK) amputation in advanced ischemia.

Comparison of long-term results of 364 femoropopliteal or femorotibial bypasses for revascularization of severely ischemic lower extremities

Successful revascularization of the severely ischemic lower extremity can be achieved by femorotibial as well as femoropopliteal bypass. The incidence of delayed graft occlusion after salvage of the severely ischemic lower extremity is low in patients with femorotibial or femoropopliteal bypass. Femorotibial bypass was performed in over one-third of patients undergoing bypass. Tibial bypasses resulted in effective prolonged revascularization of the severely ischemic lower extremity. An aggressive diagnostic and therapeutic approach to revascularization of the severely ischemic lower extremity can result in prolonged limb salvage by tibial or popliteal bypasses in lieu of primary amputation.

Aorto-iliac reconstruction with special reference to the extraperitoneal approach

We have used the extraperitoneal approach for aorto-iliac reconstruction for lower limb ischaemia in over 130 patients. The operative exposure is excellent. Operating time is shortened and the upset to the patient much less than in the transperitoneal approach. We now believe that the method is suitable for use in the majority of aorto-iliac reconstructions. Patency rate 4 years after surgery for claudication is 89 per cent.

Ischemic bowel disease

The clinical, radiologic and pathologic features of 25 cases of ischemic bowel disease are presented. The majority of patients presented with the triad of abdominal pain, diarrhea and vomiting. In 13 patients the diarrhea was associated with the passage of bright red blood per rectum. There were 10 cases of infarction, 11 of enterocolitis and 4 had resulted in stricture formation. In five cases of enterocolitis the lesion was transient; symptoms improved with conservative medical management and the radiologic findings returned to normal. Barium enema examination yielded abnormal findings in the majority of the cases in which it was performed. Plain films of the abdomen, however, were not helpful. The actual mortality in this group of patients was 44%, 80% in those with infarction of the bowel and 20% in the other two groups.

Resistance to post-traumatic fluid loss at different ages

The ability to withstand post-traumatic fluid loss in a thermoneutral environment has been studied in the rabbit during the first 3 weeks of life.

The LD₅₀ period of bilateral hind-limb ischaemia, calculated by probit analysis, fell from birth to the 10th day of life and then returned to the 1-2 day level by the 22nd day.

The difficulties of defining the acute injury to the animal are discussed and it is concluded that the fluid loss from the circulation expressed as a fraction of the plasma volume or total body water is the most precise. To compare the resistance of different age groups the fluid loss required to kill one half of a group of rabbits (i.e. the fluid loss following an LD₅₀ period of ischaemia) was calculated at each age studied. When the changes in body composition with age had been taken into account the 1-2 day-old rabbit was more resistant to post-traumatic fluid loss in a thermoneutral environment than the older animal. The possible clinical significance of these results is briefly discussed.