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Biomedical subjects

D M Coldwell

Publications and source records attributed to D M Coldwell.

At least 37 records · Page 2Linked to original sources
PubMed1995

Evaluation of the portal venous system before liver transplantation: value of phase-contrast MR angiography.

OBJECTIVE: The purpose of this study was to assess the accuracy of phase-contrast MR angiography with gadolinium in evaluating the patency and blood flow direction of the portal venous system; the presence, extent, and type of varices; and the patency of surgical decompressive shunts in patients before liver transplantation. This information is essential in management and care of patients with chronic liver disease and portal hypertension and those who are candidates for liver transplantation. SUBJECTS AND METHODS: Twenty-four patients with portal venous hypertension were evaluated with phase-contrast MR angiography. Two patients had surgical splenorenal shunts and one had a mesocaval shunt. Phase-contrast angiograms were acquired as a series of two-dimensional sequential coronal sections during breath-holding and after IV administration of gadopentetate dimeglumine. Correlative findings from color flow Doppler sonography, contrast-enhanced CT scanning, and conventional angiography were available in 23, 20, and 10 patients, respectively, and were used as standards. The images from each technique were analyzed independently for patency of and flow direction in the portal vein, splenic vein, superior mesenteric vein, and surgically created shunts, and for detection, distribution, and extent of five variceal groups. RESULTS: Findings from phase-contrast MR angiography completely agreed with those of sonography, CT scanning, and conventional angiography. The main portal vein was patent in 18 patients, stenosed in one, partially thrombosed in one, and occluded in four. Phase-contrast MR angiography correctly showed hepatofugal flow in three patients and hepatopetal flow in 17 patients. Both the splenic and superior mesenteric veins were patent in 20, partially thrombosed in one, and occluded in three cases. Phase-contrast MR angiograms showed 85% of the variceal groups, and MR rating of variceal size was not significantly different from that of CT rating. Phase-contrast MR angiography correctly showed the patency of all three surgical decompressive shunts. CONCLUSION: Phase-contrast MR angiography is accurate for evaluating the patency and flow direction of the portal venous system, detecting and determining the distribution and extent of varices, and assessing the patency of surgically created shunts. Therefore, it is a reliable and noninvasive technique that can provide crucial information in the preoperative workup of liver transplant recipients.

Adult↗
PubMed1994

Embolotherapy: agents, clinical applications, and techniques.

For embolization to be successful, three factors must be addressed: embolic agent selection, clinical application, and technical skill. The major embolic agents used include stainless steel coils, absorbable gelatin pledgets and powder, polyvinyl alcohol foam, ethanol, and glues. Each of these agents acts at different levels in the arterial system; for example, coils are equivalent to surgical ligation and occlude medium to small arteries, whereas liquid agents and the smaller diameter particles occlude at the arteriolar level or the capillary bed. The type of agent selected should also be determined according to clinical application, which includes trauma, tumors, male infertility, impotence, and vascular malformations. It may be better to occlude an artery only temporarily, particularly in trauma patients, and absorbable gelatin material is preferred for this application. Conversely, permanent occlusion of arteries with either ethanol or polyvinyl alcohol foam particles may be necessary in the treatment of tumors. To use embolotherapy effectively, the interventional radiologist must be experienced, familiar with the underlying pathologic processes, and knowledgeable with regard to the role of other specialties in the treatment of the disease process presented.

Adhesives↗
PubMed1994

Renal dysfunction due to an arteriovenous fistula in a transplant recipient.

Arteriovenous fistulae (AVF) occur after percutaneous renal biopsy in up to 18% of patients. Fistulae may remain asymptomatic or lead to hematuria, hypertension, and/or renal insufficiency. The identification of an AVF has traditionally been made with angiography; however, ultrasonography, which is less invasive and nonnephrotoxic, has become a valuable tool in the localization of a postbiopsy fistula. Most postbiopsy AVF are asymptomatic and close spontaneously. Conversely, AVF may enlarge and become symptomatic, requiring embolization to reverse or prevent complications. A case of renal insufficiency in a renal transplant recipient due to a postbiopsy AVF is presented. Spontaneous closure of the AVF resulted in the resolution of renal insufficiency. One must suspect an AVF when renal insufficiency occurs in an allograft after biopsy. Further study is needed to identify ultrasound characteristics that will predict the natural history of postbiopsy AVF.

Acute Kidney Injury↗
PubMed1992

Gangrenous cholecystitis as a complication of hepatic artery embolization: case report.

Ischemic injury to the gallbladder has been described after hepatic artery embolization but has not been considered a clinically significant complication of this procedure. We present three cases in which therapeutic embolization resulted in symptomatic gangrenous cholecystitis requiring urgent surgical intervention. Clinical parameters that distinguish this infrequent ischemic septic process from the more common postembolization syndrome are discussed and recommendations concerning the diagnosis and management of these complicated patients are outlined.

Adenocarcinoma↗
PubMed1992

Visceral angiography and embolization.

New aspects of both diagnostic and therapeutic angiography are reviewed in the context of tumor therapy, trauma, and portal hypertension. The use of intra-arterial administration of calcium gluconate as a diagnostic challenge for insulinomas, tumor embolization, and chemoembolization are reviewed. The use of angiography for proximity injuries and the therapeutic aspects of embolization in blunt hepatic, pelvic, and splenic trauma are also noted. Angiography in portal hypertension is emphasized as an adjunct to surgery. The use of the transjugular intrahepatic portosystemic shunt is reviewed and is noted to be of great promise.

Angiography↗
PubMed1991

The role of duplex scanning in the selection of patients for transluminal angioplasty.

As part of our initial evaluation to determine whether patients with lower extremity ischemia are candidates for intervention, arterial duplex examinations are performed in the noninvasive vascular laboratory. Patients with isolated short stenoses on the duplex examination are referred for transluminal angioplasty. One hundred thirty-four arteriograms were performed for ischemic peripheral vascular disease in 122 patients between July 1987 and March 1990. One hundred ten (82%) of the arteriograms were preceded by a lower extremity arterial duplex evaluation. Fifty cases (45%) were scheduled for transluminal angioplasty based on the findings of the duplex examination. Transluminal angioplasty was performed in 47 of 50 cases (94%). No significant differences in age, sex, or diabetes were found between the patients who were referred for transluminal angioplasty and those who were not. These data demonstrate that duplex scanning of the lower extremities allows the detection of lesions that will be amenable to transluminal angioplasty. We think that duplex scanning should become the standard screening tool for detection of treatable lower extremity lesions.

Angiography↗
PubMed1991

Bleeding gastroesophageal varices: gastric vein embolization after partial portal decompression.

Shunts that decompress the portal vein are effective in the treatment of bleeding esophageal varices. Use of large-caliber portacaval shunts, however, results in the complete decompression of the portal system and the risk of subsequent development of hepatic encephalopathy. Use of small-caliber portacaval shunts results in mild portal hypertension and less frequent hepatic encephalopathy but may increase the risk of recurrent bleeding. Thirty-three patients underwent angiography after partial decompression portacaval shunting (median trans-shunt pressures, 8 mm Hg). Embolization of residual varices, noted in 13 patients, was performed. Results included one complication with no sequelae and no bleeding a mean of 13 months after the procedure was performed. Trans-shunt embolization of esophageal varices effectively prevents bleeding varices after partial portal decompression.

Embolization, Therapeutic↗
PubMed1991

Ligamentous compression of the celiac axis: CT findings in five patients.

Compression of the celiac trunk by the median arcuate ligament of the diaphragm is an uncommon angiographic and surgical finding that rarely may be symptomatic. We retrospectively reviewed contrast-enhanced abdominal CT scans in five patients with severe ligamentous compression of the celiac axis, confirmed by surgery and/or angiography, and compared the findings with those of enhanced scans of 100 consecutive patients without known ligamentous compression. In all five patients with ligamentous celiac artery compression, CT showed effacement or narrowing of the celiac trunk by an anterior soft-tissue band. Dilated peripancreatic collateral vessels were seen in four cases, and poststenotic dilatation of the distal celiac trunk was seen in two cases. The normal appearance of the vasculature was seen in the majority (76%) of the 100 control subjects, but in eight patients the celiac origin was obscured on CT scans, and in 16 patients the celiac trunk appeared narrow or effaced. Our experience suggests that severe ligamentous celiac artery compression can be identified on CT. However, the isolated CT finding of effacement or obscuration of the celiac axis occurs sufficiently often in normal patients that it is not adequate evidence to establish the diagnosis of celiac artery compression.

Aged↗
PubMed1991

Hemorrhage associated with pelvic fractures: causes, diagnosis, and emergent management.

The high risk of exsanguinating hemorrhage in patients with pelvic ring disruption demands aggressive, yet balanced orthopedic and angiographic management as soon as patients are admitted to the emergency department. We present a perspective of our experience in two trauma centers and propose a logical approach to early prediction, diagnosis, and management of hemorrhage associated with pelvic fractures. Our method is based on knowledge of pelvic anatomy and an understanding of the mechanisms of injury and their wounding capacity, given that the mechanism of injury determines the type of pelvic ring disruption and that the probability of arterial hemorrhage is--to a great extent--a function of the type of pelvic fracture. The risks of diagnostic peritoneal lavage and of excessive radiologic studies of noncritical injuries are emphasized. The principles guiding arterial embolization and the application of external fixators are discussed.

Angiography↗
PubMed1990

Gunshot wounds: 1. Bullets, ballistics, and mechanisms of injury.

The nature and severity of a bullet wound depend on the characteristics of the bullet and of the tissues through which it travels. In addition to the mass and velocity of the bullet, its orientation and whether it fragments or deforms affect the nature of the wound. Two major mechanisms of wounding are described: crushing and stretching of tissue. Understanding the mechanisms by which bullets disrupt tissue can help physicians to evaluate and treat wounds.

Firearms↗
PubMed1990

Gunshot wounds: 2. Radiology.

Radiologists can contribute substantially to the evaluation and treatment of the patient with a gunshot wound. Plain films, CT, angiography, and sometimes MR imaging are used to localize the missile, determine what path it followed in the body, assess missile and bone fragmentation, and identify missile emboli. If the peritoneal cavity was entered by a bullet, a laparotomy is required. Missiles subject to magnetic forces can complicate MR imaging. Certain locations of missile fragments predispose to lead poisoning or lead arthropathy. Angiography is useful for both diagnosis and treatment. Both angiographic hemostasis and percutaneous foreign body removal may be used.

Angiography↗
PubMed1989

Regional anesthesia for hepatic arterial embolization.

Hepatic arterial embolization (HAE) has been utilized for treatment of unresectable primary and metastatic hepatic malignancies. While palliation results from this procedure, one of the major drawbacks to its use is the immediate short-term side effects, especially the right upper quadrant and epigastric pain experienced by all patients. High doses of intravenous narcotics have been used for pain control. The data on 18 patients who received a celiac plexus block immediately prior to 31 HAE procedures were compared with those on 19 control patients who underwent 42 HAE procedures without celiac plexus block. All patients who received a celiac plexus block had relief of pain without requiring intravenous analgesic both during the procedure and for the first 8 hours after HAE. These patients also subsequently received substantially lower dosages of analgesics than the control subjects. Two patients had transient hypotension due to the celiac plexus block, but no other complications occurred. It is recommended that patients undergoing HAE first receive a celiac plexus block for pain control.

Anesthesia, Conduction↗
PubMed1989

Experimental intra-arterial administration of SR-2508 in the rabbit V2 carcinoma model.

The use of the nitroimidazole radiation sensitizers, misonidazole and SR-2508, has been limited by a variety of side-effects, principally peripheral neuropathies. In order to increase the effectiveness of radiosensitization and thereby reduce the administered dose of the sensitizers, intra-arterial delivery of SR-2508 was performed and followed with 10 Gy of 4 MeV photon beam radiotherapy in the rabbit V2 carcinoma tumour model. Comparison was made with rabbits treated with an identical dose of SR-2508 given intravenously prior to photon beam radiotherapy. Control animals were treated with radiation therapy only, intra-arterial SR-2508 only, or had no treatment. Neither the radiation therapy alone nor the SR-2508 alone had any effect on tumour growth. In the intra-arterial group, the tumour growth was slower and the size was significantly smaller than all other groups. The results suggest that the intra-arterial infusion of the radiation sensitizer produces greater response of the tumour than intravenous infusion when each is combined with radiation therapy.

Animals↗
PubMed1989

Arterial injury complicating knee disruption. Third place winner: Conrad Jobst award.

Because dislocation of the knee (DK) is accompanied by a substantial risk of popliteal artery injury, the importance of arteriography in ruling out occult arterial damage in such patients is well accepted. However, because antecedent DK cannot be ruled out in a trauma victim presenting only with severe knee ligamentous disruption (LD), we have routinely performed arteriography in all patients presenting with grossly unstable knees, whether or not DK is present. To evaluate this policy we reviewed the records of 30 patients with either DK (n = 19) or severe LD (n = 11). There was no significant difference between DK and LD in the frequency of major (22% vs 18%) or minor (38% vs 36%) vascular abnormalities. We also found that Doppler pressure measurements were highly predictive of major arterial trauma in patients in whom it was used. We conclude that arterial injury should be ruled out in all trauma victims with severe knee ligament disruption, whether or not actual joint dislocation is present.

Adult↗
PubMed1989

Transcatheter therapy for malignant neoplasms.

Interventional radiology has developed into a subspecialty with application in the treatment and palliation of patients with advanced malignant diseases. A directed catheter delivers high concentrations of chemotherapy directly into the tumor bed. Embolic particles may be injected to stop hemorrhage or to occlude the blood supply of a cancer, resulting in pain relief or tumor shrinkage. These techniques can be incorporated into a multidisciplinary approach to cancer.

Catheterization↗