Renal ablation with absolute ethanol. Mechanism of action.

The mechanism of renal ablation by intra-arterial ethanol was studied in 16 mongrel dogs. Ethanol injection rates were varied, and light and electron microscopic studies were performed to detect early parenchymal changes in the kidneys. Pure ischemic injury was also studied as a control. Findings showed extensive parenchymal injury plays a significant role in renal ablation with permanent thrombosis as a delayed event. Acute arterial occlusion occurred with slow ethanol injection rates due to embolization by damaged blood components.

Ablation of renal tumors with absolute ethanol: a new technique.

Transcatheter injection of absolute ethanol into the renal artery is an effective method of producing renal ablation. There has been no evidence of inadvertent damage to vessels or tissues remote from the target organ. The "postembolization syndrome" of pain, nausea, vomiting, and fever is minimal when compared with other methods of renal artery occlusion. Multiple mechanisms of action of intraarterial ethanol are proposed, including perivascular tissue toxicity, sludging of erythrocytes in small arteries, small artery spasm, and endothelial damage. Experience with this technique in six patients has resulted in specific recommendations regarding the amount and method of injection of ethanol. Angiographic criteria indicating adequate renal ablation are described.

Systemic embolization as a complication of transhepatic venography.

Many patients with cirrhosis and portal hypertension demonstrate a right-to-left shunt, caused by development of anastomoses connecting the high-pressure periesophageal veins with the low-pressure bronchial and/or pulmonary veins at the level of the pulmonary hili. These anastomoses from the pathway by which small Gelfoam particles injected into the coronary or short gastric veins may embolize the systemic arterial circulation. Such embolization could have serious consequences, but reports of such complications have not been found by the authors.

Surgical correction of posttransplant renovascular hypertension.

The incidence of renovascular hypertension in the transplanted kidney is reported to range between 5 and 15%. A review of 391 consecutive renal transplant patients revealed 16 patients (5.4%) with hypertension secondary to partial obstruction of renal arterial blood flow. The clinical course of this group of patients was marked by early normotension followed by progressive diastolic pressure elevation, with improving renal function and loss of accumulated excess volume. Five etiologic factors are responsible for impaired arterial flow in this group of patients. Indication for operation was based on hypertension and/or impaired renal function. Patch angioplasty using saphenous veins was the procedure of choice in most instances. The average blood pressure was 185 mmHg; systolic/125 mmHg; diastolic preoperatively, compared with 140 mmHg; systolic/90 mmHg: diastolic postoperatively. Twelve of 16 patients had good results, and improvement in renal function was observed in eight patients. Serum renin levels did not correlate well with the operative findings. The use of meticulous technique, combined with maximum use of autogenous tissue, is emphasized.

Renal infarction with absolute ethanol.

Selective renal artery catheterization was undertaken in a series of mongrel dogs. Absolute ethanol was injected on a dose/weight ratio. Venous blood ethanol levels were monitored. Pre- and postprocedure angiography was performed to evaluate the effectiveness of the injection. The dogs were subsequently sacrificed and pathologic examination performed. Renal infarction was produced in all animals. Systemic blood alcohol levels remained consistently below established criteria of toxic levels. No evidence of vascular damage in systemic arteries distal to the renal artery was found. Absolute ethanol is apparently a safe and effective method of producing permanent renal infarction.

Noninvasive diagnosis of deep venous thrombosis by phleborheography.

Phleborheography, a recently described noninvasive test for deep venous thrombosis, was compared with leg venography in 75 patients. Acute deep venous thrombosis was accurately diagnosed by phleborheography in 24 patients, with no false-positive diagnoses. External venous compression without thrombosis was diagnosed correctly in two patients. The remaining patients appeared normal or had chronic venous disease by phleborheography; however, 11 of these had acute deep venous thrombosis by venography, for a false-negative rate of 31%. Most undetected thrombi were in small calf veins. The specificity of phleborheography is thus 100%, but the sensitivity is only 69%. Similarly, its positive predictive value is 100% and the negative predictive value is 78%. When phleborheography shows acute deep venous thrombosis, this diagnosis may be accepted with confidence and therapy chosen accordingly, without venographic confirmation. Venography may still be required to withhold anticoagulation when phleborheography is negative.

The cutoff characteristics of rotating grids.

The cutoff characteristics of rotating grids are qualitatively and quantitatively different from those of comparable stationary grids. Rotating grids focus to a point in space so lateral decentering occurs in all directions from the central axis of the grid. Consequently, they cannot be used for oblique radiographic techniques. For any type or amount of decentering, cutoff is approximately one-third less for rotating grids.