Biomedical subjects

T S Riles

Publications and source records attributed to T S Riles.

At least 55 records · Page 3Linked to original sources

PubMed1993

Differences in carotid shunt flow rates and implications for cerebral blood flow.

A wide variety of carotid shunts are available for use in extracranial carotid surgery. Since it is commonly assumed that when properly positioned all shunts are equal in ability to protect the brain from cerebral ischemia, the choice of shunt is usually based on handling characteristics. However, after an intraoperative stroke occurred in a patient, we compared shunt flow rates using a simple and reproducible method of measurement. A mock circuit was created using a saline-filled fluid reservoir connected to the particular shunt being tested via 1/2-inch tubing. Hydrostatic pressure across the shunt was varied by changing the height of the reservoir, and the flow was collected over 30-second intervals. Multiple flow rate measurements were performed for each shunt with pressure gradients varying from 25 to 150 cm H2O. The data show significant hemodynamic differences among commercially available carotid shunts. A pressure gradient of 75 cm H2O produced a 2.8-fold variation in the amount of fluid delivered by various shunts. Minimal cerebral blood flow requirements and the possibility of underperfusion require that the surgeon consider such data in choosing an appropriate carotid shunt.

Blood Flow Velocity↗

PubMed1993

Reconstruction of the ligated external carotid artery for embolization of cervicofacial arteriovenous malformations.

PURPOSE: Until recently, the accepted management of life-threatening complications of unresectable cervicofacial arteriovenous malformations (AVMs) has been ligation of the major feeding vessels, usually the branches or the main trunk of the external carotid artery. Rapid enlargement of collateral vessels around the ligature is usually associated with an early return of symptoms. Percutaneous transcatheter embolization of the nidus of the arteriovenous malformation is now the preferred treatment for symptomatic AVMs that cannot be excised. Previous ligation of the main feeding vessels prevents catheter access and embolization therapy of the lesion. The purpose of this report is to describe our experience with the treatment of patients with symptomatic unresectable cervicofacial AVMs and previous external carotid artery ligation. METHODS: Six patients with symptoms from cervicofacial arteriovenous malformations required surgical reconstruction of their previously ligated external carotid artery with the anticipation of catheter embolization therapy to the branch vessels feeding the malformation. Saphenous vein was used in five reconstructions; a polytetrafluoroethylene graft was used in one. RESULTS: After successful arterial reconstruction, massive swelling of the tongue and perioral tissue developed in two patients, which necessitated tracheostomy in one patient; and embolization therapy before extubation could be safely performed in the other patient. In all, four patients underwent successful embolization therapy. One refused subsequent treatment. In one patient with severe epistaxis, external carotid artery revascularization led to the healing of the nasal ulcers without need for embolization therapy. CONCLUSIONS: For patients with previous ligations of the external carotid artery and symptomatic AVMs, revascularization of the external carotid artery is an important step in treatment. The surgery must be carefully coordinated with the interventional radiologist for possible emergency postoperative embolization therapy. External carotid artery ligation only complicates the treatment of patients with cervicofacial AVMs, and should no longer be used in the treatment of these individuals.

Adult↗

PubMed1993

Long-term follow-up of patients undergoing reoperation for recurrent carotid artery disease.

PURPOSE: We examined the perioperative course and long-term fate of individuals who required reoperation for recurrent carotid artery disease. METHODS: The records of 2289 patients undergoing 2961 consecutive operations during a 22-year period were reviewed. Forty-two patients (1.8%) who underwent reoperations were studied. Forty-seven redo carotid artery reconstructions were performed on these 42 patients for neurologic symptoms or asymptomatic high-grade stenosis. Long-term follow-up was obtained on 41 of 42 patients (mean 54 months; range 9 to 202 months). RESULTS: The forty-seven reoperations consisted of endarterectomy with patch angioplasty (n = 36), saphenous vein or polytetrafluoroethylene interposition graft (n = 7), or simply vein or polytetrafluoroethylene patch angioplasty (n = 4). There were no perioperative strokes or deaths. Three patients had perioperative transient ischemic attacks and two had cranial nerve injuries. The incidence of late failure after secondary surgery was 19.5% (8/41 patients). These failures consisted of one stroke, three transient ischemic attacks, and four asymptomatic occlusions. One tertiary carotid artery reconstruction was performed for a restenosis at the site of the secondary reconstruction. CONCLUSION: The factors responsible for the high incidence of late failures after secondary carotid artery reconstruction are unclear. Reoperation for recurrent carotid artery disease appears less durable than primary carotid endarterectomy. Close postoperative surveillance is recommended after carotid artery reoperation.

Adult↗

PubMed1993

Abdominal aortic pseudoaneurysm after blunt trauma.

A 4-year-old male child was admitted with a large 12 x 15 cm suprarenal abdominal aortic pseudoaneurysm 7 months after an episode of blunt abdominal trauma. Aneurysmorrhaphy was performed through a left thoracoabdominal approach with Dacron patch aortoplasty. This report summarizes this case and reviews the literature on abdominal aortic pseudoaneurysms after blunt abdominal trauma.

Abdominal Injuries↗

PubMed1992

Silent myocardial ischemia monitoring predicts late as well as perioperative cardiac events in patients undergoing vascular surgery.

In a previous study we have shown that perioperative monitoring for silent myocardial ischemia can noninvasively identify those patients undergoing peripheral vascular surgery who are at significantly increased risk for perioperative myocardial infarction. In the present study a group of 385 patients undergoing peripheral vascular surgery was studied long-term as well as short-term to determine whether perioperative monitoring for silent ischemia can identify those patients who are at significantly increased risk of late cardiac death or late cardiac complications as well as those patients at increased risk of perioperative myocardial infarction. All patients were monitored before, during, and after operation and were divided into two groups on the basis of results of monitoring: patients whose total duration of silent ischemia as a percentage of the total duration of perioperative monitoring was 1% or greater (group I, n = 120) and those for whom this value was less than 1% (group II, n = 265). Among patients in group I 13.3% (16 of 120) suffered a perioperative myocardial infarction in contrast to only 1.1% (3 of 265) patients in group II (p less than 0.001). Multivariate logistic regression analysis of preoperative and perioperative characteristics showed that the presence of a total perioperative percent time ischemic 1% or greater and age were the only significant predictors of perioperative myocardial infarction.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗

PubMed1992

The influence of human immunodeficiency virus infection and intravenous drug abuse on complications of hemodialysis access surgery.

To examine the influence of human immunodeficiency virus (HIV) infection on complications in dialysis access surgery, a review was performed on patients undergoing hemodialysis at two major metropolitan medical centers over a 30-month period. One hundred eight patients underwent a total of 169 graft procedures; mean follow-up was 14 1/2 months. There were 18 (17%) patients who were HIV-positive who had no symptoms, 11 (10%) patients with acquired immunodeficiency syndrome (AIDS), and 79 (73%) patients who were HIV-negative. Twenty-three percent (25/108) of patients had a history of intravenous drug abuse (IVDA), most of whom also had either AIDS or asymptomatic HIV infection. Dialysis procedures included 44 autogenous reconstructions (26%), 117 polytetrafluoroethylene (PTFE) grafts (69%), and 8 (5%) procedures of unknown type. Arteriovenous fistula or graft thrombosis was a frequent complication. The overall 12-month graft patency rate was 41%, and patients with HIV infection or a history of IVDA did not have a significantly increased risk of thrombosis. Multivariate analysis showed that the use of PTFE as opposed to autogenous reconstruction was the only significant risk factor found for occlusion within the first 12 months after operation (p < 0.01). Twenty-five graft infections occurred, all in PTFE grafts. The PTFE graft infection rate was 43% in patients with AIDS, 36% in patients who were HIV-positive and who had no symptoms, and 15% in patients who were HIV-negative (p < 0.05). Patients with a history of IVDA had a 41% PTFE graft infection rate versus a 13% infection rate in patients who did not have a history of IVDA (p < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1992

Comparison of magnetic resonance angiography, conventional angiography, and duplex scanning.

BACKGROUND AND PURPOSE: To determine the accuracy of magnetic resonance angiography in assessing patients with cerebrovascular disease, we performed a study comparing the results of conventional cerebral angiography, duplex scanning, and magnetic resonance angiography. METHODS: From 42 patients, a total of 25 carotid arteries were evaluated by all three techniques. The studies were independently read and sorted into five categories according to the degree of stenosis: 0-15%, normal; 16-49%, mild; 50-79%, moderate; 80-99%, severe; and totally occluded. RESULTS: Magnetic resonance angiography correlated exactly with conventional angiography in 39 arteries (52%); duplex scanning correlated with conventional angiography in 49 cases (65%). Compared with conventional angiography, both magnetic resonance angiography and duplex scanning tended to overread the degree of stenosis. The most critical errors associated with magnetic resonance angiography were three readings of total occlusion in vessels found to be patent on conventional angiograms. CONCLUSIONS: Although magnetic resonance angiography offers great hope of providing high-quality imaging of the carotid artery with no risk and at less cost, data from this study suggest that misreading the degree of stenosis, or misinterpreting a stenosis for an occlusion, could lead to errors in clinical decisions. Guidelines for use of magnetic resonance angiography in a clinical setting are offered.

Adult↗

PubMed1991

Vertebral artery angioplasty in patients younger than 55 years: long-term follow-up.

Since 1964 we have performed 136 vertebral artery reconstructions representing 4% of all operations on extracranial cerebral arteries by our staff. Fifteen of our patients were under age 55 years and had symptoms of dizziness, bilateral visual disturbances, ataxia, presyncopal episodes, and occasionally localized extremity weakness. Dizziness, often severe and incapacitating, has been the most common and consistent symptom. The diagnosis of vertebral artery lesions was made using aortic arch four-vessel cerebral arteriography. Operations were performed for severely obstructing bilateral vertebral artery lesions and included only unilateral vertebral vein patch angioplasty with or without suture plication of the artery in 13 patients. Unilateral carotid vertebral bypass was performed in one patient and unilateral vertebral reimplantation to the carotid in another. Follow-up averaged 8.9 years, ranging from ten months to 20 years. Eleven of 15 patients have remained asymptomatic and without strokes. Recurrent dizziness was present in three, two of whom had vertebral arteriography showing patent vertebral reconstructions. Another had a stroke related to the anterior circulation in follow-up at nine years. Atherosclerotic obstruction of vertebral arteries does occur in patients in the preatherosclerotic age group. Even atypical symptoms suggestive of vertebrobasilar insufficiency may be associated with isolated correctable bilateral flow-impeding vertebral lesions. These symptoms warrant evaluation with cardiac neurological and cerebrovascular studies. Vertebral angioplasty relieves symptoms and the incidence of stroke during follow-up is low.

Arteriosclerosis↗

PubMed1991

Redo endarterectomy for recurrent carotid artery stenosis.

From a registry of 2406 carotid endarterectomies performed on 1818 patients over a 19-year period, 29 patients (1.6%) underwent reoperations for recurrent stenosis. Reoperations were performed for symptomatic stenosis for 23 and asymptomatic greater than 80% stenosis for six patients. Compared to the entire series, there was no difference in the incidence of restenosis for men and women. The pathologic findings were myointimal hyperplasia in 27%, atherosclerosis in 53%, thrombus with vessel dilatation in 17% and extrinsic scar in 3%. Redo endarterectomy with patch angioplasty was used for reconstruction in 27 patients and patch angioplasty alone in two. There were no operative deaths or strokes. Late follow-up (mean 50 months) revealed only one stroke and six other deaths. Although 21 (75%) were alive and stroke-free, follow-up studies suggest a high incidence (21%) of tertiary lesions among patients who have undergone redo endarterectomy for recurrent stenosis.

Aged↗

PubMed1991

Celiomesenteric anomaly and aneurysm: clinical and etiologic features.

The development of aneurysmal disease involving the rarely encountered celiomesenteric anomaly is extremely unusual. Aneurysmal disease of the celiac or superior mesenteric arteries is itself an extremely uncommon finding, accounting for less than 10% of all visceral artery aneurysms. The existence of aneurysmal disease involving a celiomesenteric anomaly has been alluded to only briefly in two previous clinical reports. We review the case of a young woman with aneurysmal disease involving a common celiomesenteric trunk. The patient underwent excision of the aneurysm with successful vascular reconstruction. Although extremely unusual, the development of this extremely rare lesion can be predicted on the basis of specific etiologic theories. Variations in the patterns of embryologic formation of the visceral arteries account for the development of celiomesenteric anomalies, whereas atherosclerosis, medial degeneration, and infection lead to the development of most visceral aneurysms. Surgical treatment of celiac or mesenteric aneurysms is almost always indicated. Awareness of potential vascular anomalies and patterns of collateral circulation are necessary for appropriate surgical intervention.

Aneurysm↗

PubMed1991

Angiosarcoma at the site of a Dacron vascular prosthesis: a case report and literature review.

Four of 32 reported sarcomas related to the aorta have arisen around previously placed aortic vascular prostheses suggesting that the graft may have been an etiologic factor. Our recent experience with such an angiosarcoma arising around a Dacron aortic graft prompted a review of the lesion to identify risk factors, diagnostic approaches, and treatment options. The diagnosis of these sarcomas is seldom made before operation. Animal studies have implicated plastic polymers including Dacron as carcinogenic materials capable of inducing sarcoma in 7% to 50% of exposures. Because of the rarity of these tumors and the thousands of vascular implants used over the past 30 years, it is unlikely that this degree of risk can be extrapolated to humans. However, a tumor should be included in the differential diagnosis of any mass or thromboembolic event associated with a vascular prosthesis.

Aorta, Thoracic↗

PubMed1990

Should proximal saphenous vein be used for carotid patch angioplasty: a clinical study of the need for vein in subsequent operations.

Reluctance to use saphenous vein (SV) for patch closure of the carotid arteriotomy is due in part to the concern of vascular surgeons that the SV should be preserved for possible future coronary or lower extremity reconstruction. Even among those who favour vein patch closure of the arteriotomy for improved immediate and late results, an effort has been made to use the ankle portion of the SV, preserving the upper, larger segment for later surgery. Recent reports of rupture of the patches formed from ankle SV and a study showing a decrease in strength of the ankle segment of vein, raised the question of the importance of trying to preserve the proximal SV and the impact of use of this segment in those patients requiring secondary vascular procedures. We reviewed 134 consecutive carotid patients from 1981 who had proximal SV harvested for patch angioplasty. Of those 122 were available (mean 44.9 months). Thirteen had secondary vascular procedures. Adequate saphenous vein was available in twelve. We conclude from this study that (1) less than 15% of patients undergoing carotid surgery will require a secondary vascular surgery within 5 years and (2) harvesting SV from the thigh rarely compromises future revascularisation.

Aged↗

PubMed1990

Carotidynia managed by surgical denervation of the carotid bulb.

Carotidynia is a syndrome of pain in the neck and face accompanied by local tenderness of the carotid artery. The symptoms are often misdiagnosed due to similarities with more common syndromes involving the cervical region. Spontaneous remission is common; more severe cases generally respond to anti-inflammatory medication or prophylactic drugs used for migraine. A case of severe carotidynia, unassociated with migraine is reported. Failure to respond to medical therapy led to surgical denervation of the carotid bulb. The immediate relief of symptoms following surgery confirms earlier observations regarding the mechanism of the symptoms. In severe cases of carotidynia, surgical denervation of the carotid artery may be indicated if medical therapy has failed.

Adult↗

PubMed1990

[Need for surgery in asymptomatic carotid stenosis].

1. Asymptomatic carotid stenosis up to 80% do not require prophylactic surgery, but should be followed non-infasively. 2. Stenoses of 80-99% are associated with a significant incidence of stroke which is estimated to be 4-10%/year. 3. Occlusion is considered to be an unfavorable end point, since the risk of stroke remains higher than those with patent arteries. 4. The role of carotid endarterectomy is related to the stroke morbidity and mortality of the procedure. To show significant benefits of surgical therapy during the first two years, it is necessary to have a stroke/death rate of less than 3%.

Carotid Stenosis↗

PubMed1990

Rupture of the vein patch: a rare complication of carotid endarterectomy.

Vein patch closure after carotid endarterectomy has been used to reduce the incidence of residual and recurrent stenosis at the carotid bifurcation. A rare but potential serious complication is rupture of the vein patch during the early postoperative period. In our experience of 2359 carotid operations performed from 1962 through 1986, saphenous vein was used for closure in 2275 (96.5%) operations. In three patients out of 75 in whom the vein patch had been harvested from the ankle, rupture of the patch occurred 2 to 5 days after uneventful carotid surgery. At emergency reoperation, the central portion of the vein was necrotic, with no evidence of infection. In each case the carotid artery was closed again with fresh thigh saphenous vein, and recovery was uneventful. The use of ankle vein was discontinued in December 1983 in favor of groin saphenous vein, and similar complications have not occurred in more than 600 carotid endarterectomies performed since. Early noninfectious ruptures of the saphenous vein patches have been mentioned in other reported series of carotid operations and have often been related to the use of ankle vein, but they remain unexplained.

Carotid Arteries↗

PubMed1989

Beta blockade to decrease silent myocardial ischemia during peripheral vascular surgery.

The incidence and duration of intraoperative silent myocardial ischemia have been shown to be significantly correlated with the incidence of perioperative myocardial infarction in patients undergoing peripheral vascular surgery. To assess the effectiveness of intraoperative beta blockade in limiting such silent myocardial ischemia, a group of 48 patients was treated with oral metoprolol immediately prior to peripheral vascular surgery. The total duration of intraoperative silent myocardial ischemia, the percentage of intraoperative time silent myocardial ischemia was present, the number of intraoperative episodes of silent myocardial ischemia, and the intraoperative heart rate in the treated patients were compared with those in 152 similar but untreated peripheral vascular surgery patients. The patients treated with oral metoprolol had significantly less intraoperative silent ischemia with respect to relative duration and frequency of episodes, a significantly lower intraoperative heart rate, and less intraoperative silent myocardial ischemia in terms of total absolute duration. These results suggest that beta-adrenergic activation may play a major role in the pathogenesis of silent myocardial ischemia during peripheral vascular surgery.

Adrenergic beta-Antagonists↗

PubMed1989

The value of silent myocardial ischemia monitoring in the prediction of perioperative myocardial infarction in patients undergoing peripheral vascular surgery.

Real-time electrocardiographic monitoring for silent myocardial ischemia was performed on 200 patients undergoing peripheral vascular surgery to try to better define those at high risk of perioperative myocardial infarction. The patients were divided into those undergoing abdominal aortic aneurysm or lower extremity revascularization procedures (group I, n = 120) and those undergoing carotid artery endarterectomy (group II, n = 80). Silent ischemia was detected during the preoperative, intraoperative, or post-operative periods in 60.8% of group I and 67.5% of group II patients. Six group I and three group II patients suffered an acute perioperative myocardial infarction with two cardiac deaths. In both groups I and II a variety of parameters based on monitoring of silent myocardial ischemia were compared between the subgroups of patients who had myocardial infarction and those who did not. The results show that in both groups there was a significantly (p less than or equal to 0.05) greater total duration of perioperative ischemic time, total number of perioperative ischemic episodes, and total duration of perioperative ischemic time as a percent of total monitoring time in patients who suffered a perioperative myocardial infarction compared to those who did not. Multivariate logistic regression analysis of preoperative characteristics in all 200 patients showed the occurrence of preoperative silent myocardial ischemia and angina at rest to be the only significant predictors of perioperative myocardial infarction. Thus perioperative monitoring for silent myocardial ischemia might noninvasively identify those patients undergoing peripheral vascular surgery who are at increased risk for perioperative myocardial infarction, permitting implementation of timely preventive measures in selected patients.

Aged↗

PubMed1989

Is duplex scanning sufficient evaluation before carotid endarterectomy?

Recent reports have suggested that cerebral angiography may not be necessary before carotid endarterectomy is performed in selected patients. To determine if arteriography provides additional information that might influence the decision to operate or the conduct of the operation, a retrospective review was performed of 100 consecutive patients undergoing cerebral angiography and carotid duplex scanning. Eighty of the 100 patients subsequently underwent carotid endarterectomy for neurologic symptoms or asymptomatic stenosis greater than 80%. Among the 20 patients not operated on, three would have undergone unnecessary surgery for mistaken diagnoses had the arteriogram not been obtained. Two other patients in this group of 20 would have had carotid endarterectomy for asymptomatic stenosis in the presence of an equally stenotic tandem lesion. Among the 80 patients operated on, an additional three had the operative procedure altered because arteriographic studies revealed pathologic findings outside the area of duplex scan examination. Thus the use of arteriography altered the management of eight (8%) patients in this group of 100.

Aged↗