The spiral wave frequency effect in atrial fibrillation

A spiral wavefront (WF), generated by a cardiac rotor that drifts between surface electrodes during atrial fibrillation, exhibits frequency changes inconsistent with classical Doppler effect (CDE) phenomena. Recent clinical studies reveal three repeatedly observed events--1) side-dependent frequency changes across the path of the rotor, 2) one additional WF strike on the higher frequency side, and 3) a reversal of WF strike sequence--which constitute a diametrical property of spinning WF sources. A linear ray model is first used to reveal and develop the diametrical phenomena. Mathematical models of an Archimedean spiral and a spiral generated by the diffusion equation are developed and compared. Each formulation predicts the diametrical property that CDE does not capture and illuminates the occurrence of a strong side and weak side with respect to the rotor path. Whereas CDE exhibits higher and lower frequencies from approaching and receding sources of WFs, respectively, spiral rotors generate higher and lower frequencies on opposite sides of the migration path. This motivates the reconsideration of mapping and ablation strategies that have traditionally been based on identifying sites of the dominant frequency. While this research aims to characterize the path of a spiral rotor during atrial fibrillation accurately, the results are applicable in other fields of science and engineering in which rotating spiral waves occur.

Visual laser ablation of the prostate: clinical experience in 108 patients

Visual laser ablation of the prostate was performed on 108 patients (ages 44 to 84 years) as an outpatient procedure from May 1992 to October 1992. Preoperatively, the patients underwent digital rectal examinations, determination of prostate specific antigen levels and transrectal ultrasound guided biopsies when necessary to rule out the presence of prostate cancer. The Urolase laser fiber delivery system was used to transmit laser energy from a neodymium: YAG generator. For the 97 patients with preoperative and postoperative American Urological Association symptom index testing, scores decreased by an average of 12.59 (p < 0.001). For the 75 patients with preoperative and postoperative uroflow rates an average increase of 4.92 ml. per second (p < 0.001) was noted following the procedure. Only 3 patients required hospitalization for an average of 1.33 days. No patient required a blood transfusion. There have been no fluid or electrolyte abnormalities following visual laser ablation of the prostate. There have been no recognizable urethral strictures, deaths or postoperative sepsis. Only 3 patients experienced retrograde ejaculation. We found visual laser ablation of the prostate to be a cost-effective and less morbid alternative to traditional transurethral resection of the prostate.

Submucosal ureteral calculi: a new entity?

We describe 3 patients with ureteral calculi who failed multiple extracorporeal shock wave lithotripsy treatments and whose stones could not be visualized by ureteroscopy despite radiological confirmation. We contend that these ureteral stones migrated submucosally and are refractory to the aforementioned treatment modalities. Each patient had a common presenting complaint of intermittent flank pain 5 years in duration, leading us to believe that long-standing stone impaction is a prerequisite for this entity. Our experience is reviewed.

Extracorporeal shock wave lithotripsy and the ureteral stone brush: initial results

We present the initial results of a ureteral stone brush used in conjunction with extracorporeal shock wave lithotripsy for impacted ureteral stones. We studied 31 cases of ureteral calculi that could not be manipulated back into the renal collecting system. In 18 cases a ureteral catheter was placed past the calculus, while in 13 a catheter could not be passed. With the stone brush unbypassed stones yielded a success rate similar to that for bypassed stones (84.6 versus 88.9%, respectively). We believe that this result is due to the ability of the stone brush to remove circumferential fragments from around the stone, allowing more shock energy to reach the core of the stone.

Use of stone brush for treatment of impacted stones in association with extracorporeal shock-wave lithotripsy

A new device is described which enhances the treatment of impacted stones in association with the extracorporeal shock-wave lithotripsy. This technique may result in decreased number of shocks and increased efficiency, as well as, enhance outpatient treatment.

Variation on Water-Pik technique for treatment of steinstrasse after ESWL

A new variation on the Water-Pik technique for treating steinstrasse after extracorporeal shock-wave lithotripsy is described. This technique is simple and effective and can be adapted for use in virtually any standard cystoscopy suite.

Intraoperative localization of renal calculi using the Polarex 2 C-arm image intensifier

We present our experience with the C-arm image intensifier in the localization of renal calculi. We have found this technique to be exceptionally easy to use and extraordinarily efficient. However, unless the disk images are used primarily, rather than continuous fluoroscopy, the radiation exposure can be significant. This technique can be somewhat limiting in that exceptionally small stones or poorly opacified stones cannot be picked up easily.

Transitional cell carcinoma of the kidney 25-year experience

Seventy patients with transitional cell carcinoma of the kidney operated upon at Barnes Hospital during the last 25 years are reviewed. The relationship of the pathologic stage, grade, findings on excretory urography and survival is studied. The stage and survival rates were predicted fairly accurately on the basis of the excretory urogram alone. Survival of patients was determined occasionally by the status of the associated bladder tumors more than by the renal cancer. Because of tumor multiplicity we recommend total nephroureterectomy as the treatment of choice. The role of radiation therapy is considered.

An incision for extended suprahilar retroperitoneal lymphadenectomy

To fulfill the necessary criteria for adequate exposure for extended suprahilar retroperitoneal lymphadenectomy we have used a thoracoabdominal midline extraperitoneal incision that affords the high exposure of a thoracoabdominal incision without sacrificing the broad exposure afforded by a midline incision and maintains the advantages of the extraperitoneal approach.

Acetazolamide-induced renal calculi

The occurrence of urinary calculi associated with acetazolamide therapy is described. Patients with a history of urinary stones or surgery are a significant risk for further calculus formation when treated with acetazolamide. The concurrent use of sodium bicarbonate further potentiates this risk.