Biomedical subjects
Publications and source records attributed to A W Stanson.
We report two cases of paradoxical cerebrovascular embolism associated with intrapulmonary arteriovenous fistulas. In both cases the diagnosis was made by the use of contrast transoesophageal echocardiography, which not only detected the fistulas but also localized the arteriovenous fistula to specific pulmonary vascular beds.
Abdominal aortic aneurysms (AAAs) in children and young adults are rare; some have been observed in patients with tuberous sclerosis (TS). We report two cases and review the literature. A 9-year-old girl with TS was diagnosed with a 3-cm calcified AAA, and a 41-year-old man with TS was diagnosed with a 7.5-cm thoracic aortic aneurysm (TAA). Both patients underwent open repair with a tube polyester graft without complication. They are both doing well at 7 and 8 years after surgery. Pathologic evaluation revealed medial atrophy and focal medial disruption in the aortic wall in both patients. With our two cases, 15 patients with TS and aneurysms have been reported; 12 had AAA, and four had TAA (one patient had both). Three AAAs and two TAAs ruptured. Six patients died because of aneurysmal disease. There is an association between TS and aortic aneurysms. Patients should be screened for aortic aneurysms at the time TS is diagnosed and annually thereafter. Because of the high risk of rupture, early elective repair is suggested. New aortic aneurysms after repair may also develop.
OBJECTIVES: Assessments of outcome after reconstruction for critical limb ischemia frequently ignore functional result and long-term morbidity and mortality. This study was undertaken to identify factors affecting long-term clinical outcome and survival after pedal bypass grafting. METHODS: The clinical data of 256 consecutive patients who underwent pedal bypass grafting for critical limb ischemia over a 12-year period were retrospectively analyzed. RESULTS: A total of 174 men and 82 women (median age, 70 years; range, 30-91 years) underwent 280 pedal bypass graft placements with autologous vein. Seventy-five percent of the patients were diabetic, and 20% had renal insufficiency (serum creatinine level > 2 mg/dL). The in-hospital mortality rate was 1.6% (4/256). The mean follow-up was 2.7 years (range, 0.1-10.1 years). Rates of primary and secondary patency, limb salvage, and survival at 5 years were 58%, 71%, 78%, 60%, respectively. A total of 160 limbs (57%) required additional interventions. Nineteen early graft thrombectomies/revisions and nine early amputations were performed. One hundred thirty-eight late interventions included 31 graft salvage procedures, 27 wound debridements, and 34 minor and 42 major amputations. At last follow-up or death, 219 (78%) limbs were being used for ambulation. End-stage renal disease (ESRD) and composite vein grafts predicted limb loss (P <.001, P <.001, respectively). Overall survival at 5 years was 60%. Survival after amputation was 79%, 53%, and 26% at 1, 3, and 5 years. Amputation and ESRD predicted higher mortality (P =.014, P =.0001, respectively). CONCLUSIONS: Pedal bypass grafting resulted in good functional limb salvage, but at the expense of multiple interventions in more than half the cases. ESRD and composite vein graft were associated with poor long-term limb salvage. Amputation after bypass grafting was associated with significantly worse long-term survival.
PURPOSE: Primary chylous disorders (PCDs) are rare. Rupture of dilated lymph vessels (lymphangiectasia) may result in chylous ascites, chylothorax, or leakage of chyle through chylocutanous fistulas in the lower limbs or genitalia. Chyle may reflux through incompetent lymphatics, causing lymphedema. To assess the efficacy of surgical treatment, we reviewed our experience. METHODS: The clinical data of 35 patients with PCDs treated between January 1, 1976, and August 31, 2000, were reviewed retrospectively. RESULTS: Fifteen men and 20 women (mean age, 29 years; range, 1 day-81 years) presented with PCDs. Sixteen (46%) patients had chylous ascites, and 19 (54%) had chylothorax (20 patients), and of these, 10 (29%) had both. In 16 patients, reflux of chyle into the pelvic or lower limb lymphatics caused lymphedema (14, 88%) or lymphatic leak through cutaneous fistulae (11, 69%). Presenting symptoms included lower-limb edema (19, 54%), dyspnea (17, 49%), scrotal or labial edema (15, 43%), or abdominal distention (13, 37%). Primary lymphangiectasia presented alone in 23 patients (66%), and it was associated with clinical syndromes or additional pathologic findings in 12 (yellow nail syndrome in 4, lymphangiomyomatosis in 3, unknown in 3, Prasad syndrome (hypogammaglobulinemia, lymphadenopathy, and pulmonary insufficiency) in 1, and thoracic duct cyst in 1). Twenty-one (60%) patients underwent 26 surgical procedures. Preoperative imaging included computed tomography scan in 15 patients, magnetic resonance imaging in 3, lymphoscintigraphy in 12, and lymphangiography in 14. Fifteen patients underwent 18 procedures for chylous ascites or pelvic reflux. Ten (56%) procedures were resection of retroperitoneal/mesenteric lymphatics with or without sclerotherapy of lymphatics, 4 (22%) were lymphovenous anastomoses or grafts, 3 (17%) were peritoneovenous shunts, and 1 (6%) patient had a hysterectomy. Six patients underwent eight procedures for chylothorax, including thoracotomy with decortication and pleurodesis (4 procedures), thoracoscopic decortication (1 patient), ligation of thoracic duct (2 procedures), and resection of thoracic duct cyst (1 patient). Postoperative mean follow-up was 54 months (range, 0.3-276). Early complications included wound infections in 3 patients, elevated liver enzymes in 1, and peritoneovenous shunt occlusion with innominate vein occlusion in 1. All patients improved initially, but four (19%) had recurrence of symptoms at a mean of 25 months (range, 1-43). Three patients had postoperative lymphoscintigraphy confirming improved lymphatic transport and diminished reflux. One patient died 12 years postoperatively, from causes unrelated to PCD. CONCLUSIONS: More than half of the patients with PCDs require surgical treatment, and surgery should be considered in patients with significant symptoms of PCD. Lymphangiography is recommended to determine anatomy and the site of the lymphatic leak, especially if lymphovenous grafting is planned. All patients had initial benefit postoperatively and two thirds of patients demonstrated durable clinical improvement after surgical treatment.
PURPOSE: Klippel-Trénaunay syndrome (KTS) is a complex congenital anomaly, characterized by varicosities and venous malformations (VMs) of one or more limbs, port-wine stains, and soft tissue and bone hypertrophy. Venous drainage is frequently abnormal because of embryonic veins, agenesis, hypoplasia, valvular incompetence, or aneurysms of deep veins. We previously reported on the surgical management of KTS. In this article, we update our experience. METHODS: Twenty patients with KTS underwent surgical treatment for VMs between July 1, 1987, and January 1, 2000. This group represented 6.9% of 290 patients with KTS who were seen at our institution during this 12.5-year study period. Surgical indications, venous anatomy (determined with duplex scan, contrast phlebography, magnetic resonance imaging or magnetic resonance phlebography), operative procedures, and complications were reviewed, and outcomes were recorded. RESULTS: Twelve male and eight female patients (mean age, 23.4 years; range, 7.7-40.6 years) underwent 30 vascular surgical procedures in 21 lower limbs. All 20 patients (100%) had varicose veins or VMs, 13 (65%) had port-wine stains, and 18 (90%) had limb hypertrophy. Pain was the most common complaint, which was present in 16 patients (80%), followed by swelling in 15 (75%), bleeding in 8 (40%), and superficial thrombophlebitis and cellulitis in 3 (15%). Imaging confirmed patent deep veins in 18 patients, hypoplastic femoral vein in 1, and entrapped popliteal veins bilaterally in 1. Four patients (20%) had large persistent sciatic veins (PSVs). The CEAP clinical classification was C-3 for 17 patients (85%), C-4 for 1 patient (5%), and C-6 for 2 patients (10%). Stripping of large lateral veins, avulsion, and excision of varicosities or VMs were performed on all limbs. Three patients required staged resections. The release of entrapped popliteal veins was performed in both limbs of one patient; another underwent a popliteal-saphenous bypass graft. One patient underwent excision of a PSV. Open and endoscopic perforator vein ligation was performed in one patient each. Two patients (12%) had hematomas that required evacuation. No patients had caval filter placement; none had postoperative deep venous thrombosis or pulmonary embolus. The mean follow-up was 63.6 months (range, 0-138 months). All patients reported initial improvement, but some varicosities recurred in 10 patients (50%), an ulcer did not heal in one, and a new ulcer developed in one, 8 years after surgery. Three patients underwent reoperation for recurrent varicosities. Follow-up CEAP scores were C-2 in 10 patients (50%), C-3 in 6 patients (30%), C-4 and C-5 in 1 patient each (5%), and C-6 in 2 patients (10%). Clinical scores improved from 4.3 +/- 2.2 to 3.1 +/- 2.3. (P =.03). CONCLUSIONS: The management of patients with KTS continues to be primarily nonoperative, but those patients with patent deep veins can be considered for excision of symptomatic varicose veins and VMs. Although the recurrence rate is high, clinical improvement is significant, and reoperations can be performed if needed. Occasionally, deep vein reconstruction, excision of PSVs, or subfascial endoscopic perforator surgery is indicated. Because KTS is rare, patients should receive multidisciplinary care in qualified vascular centers.
OBJECTIVE: To determine how often patients with renal artery stenosis (RAS) managed without revascularization progress to accelerated hypertension and/or renal failure. PATIENTS AND METHODS: We examined the outcomes of 68 patients (mean +/- SEM age, 71.8 +/- 0.9 years) with high-grade (>70%) RAS identified between 1989 and 1993 who were treated without renal revascularization for at least 6 months after angiography. The time to last follow-up averaged 38.9 +/- 2.8 months. Other vascular beds were affected in 66 of the 68 patients. End points were revascularization, nephrectomy, dialysis, or death. RESULTS: The mean +/- SEM serum creatinine level rose from 1.4 +/- 0.1 to 2.0 +/- 0.2 mg/dL (P<.001). Mean +/- SEM blood pressure did not change (157 +/- 3/83+/-2 vs 155 +/- 3/79 +/- 2 mm Hg), but the need (mean +/- SEM) for medication increased from 1.6+/-0.1 to 1.9+/-0.1 drugs (P=.02). Four patients (5.8%) eventually underwent renal revascularization for refractory hypertension (1 patient), for progressive stenosis (1 patient), and during aortic reconstruction (2 patients). One additional patient underwent nephrectomy to improve blood pressure control. Five others (7.4%) developed end-stage renal disease (ESRD) for reasons other than progressive vascular disease, namely, diabetes (3 patients), atheroemboli (1 patient), and contrast toxicity without RAS progression (1 patient). In 1 further case, the reason for ESRD was unknown, and it may have been caused by vascular occlusion. During follow-up, 19 patients died of unrelated causes, including myocardial infarction and stroke. CONCLUSIONS: These data indicate that antihypertensive medication requirements increased and renal function deteriorated modestly in a subset of patients with atherosclerotic RAS managed initially without vascular intervention. Many achieved stable blood pressure for many years. Deterioration of renal function and mortality risk were greatest in patients with bilateral stenosis or stenosis to a solitary functioning kidney. These results reinforce the need for meticulous follow-up for disease progression but underscore the role of competing risks and high mortality from other cardiovascular diseases, which primarily determine the outcomes in patients with RAS and widespread atherosclerotic disease.
Pulmonary arteriovenous fistulas (PAVFs) are rare vascular malformations of the lung. There is a strong association with Rendu-Osler-Weber disease. Although most patients are asymptomatic, PAVFs can cause dyspnea from a right-to-left shunt. They can also bleed and result in hemoptysis and hemothorax. Because of paradoxical emboli, various central nervous system complications have been described including stroke, and brain abscess. Currently, spiral computed tomography offers the most practical method for establishing the presence of PAVFs. Most patients should be treated. Therapeutic options include angiographic embolization with metal coils or balloon occlusion and surgical excision. Angiographic treatment has become the mainstay of therapy for most patients during the last decade. It is less invasive and can be repeated easily. Surgery, which usually consists of a conservative lung resection, is associated with low morbidity and a low recurrence rate. Both therapeutic approaches are discussed. The Mayo Clinic surgical experience of the last 20 years for PAVFs is presented.
OBJECTIVE: To describe the results of analysis of clinical, physiologic, diagnostic, and therapeutic aspects and complications in patients with pulmonary arteriovenous fistulas (PAVFs). PATIENTS AND METHODS: Retrospective review of medical records of all patients with the diagnosis of PAVF evaluated at Mayo Clinic Rochester from 1982 through 1997. Demographic characteristics, presence or absence of hereditary hemorrhagic telangiectasia, clinical features, and results of imaging studies and blood gas analyses, treatments, and complications related to PAVFs were reviewed. RESULTS: Among the 93 patients, 44 were male and 49 female. The mean age at the time of evaluation was 40 years (range, 5-83 years). Fifteen patients (16%) were asymptomatic. History of hereditary hemorrhagic telangiectasia was present in 52 patients (56%). Notable clinical findings included epistaxis in 46 (49%), hemoptysis in 14 (15%), cyanosis in 27 (29%), clubbing in 18 (19%), dyspnea in 53 (57%), and pulmonary bruits/murmurs in 32 (34%). Chest x-ray films with or without tomograms showed abnormal findings in 87 (94%), of which 68 (73%) suggested PAVF. Polycythemia was detected in 12 (13%). Pretherapy arterial PO2 measured on room air averaged 56 mm Hg (range, 32-95 mm Hg), and the posttherapy PO2 averaged 77 mm Hg (range, 46-110 mm Hg). Echocardiography with indocyanine green dye was diagnostic of extracardiac right-to-left shunt in 26 (90%) of 29 patients tested. Diagnostic studies revealed single lesions in 32 patients (34%) and multiple lesions in 61 (66%). The most prominent complications of the disease were neurologic events in 34 patients (37%). These complications included transient ischemic attacks, hemiplegia, brain abscesses, and seizures. Surgical resection alone was carried out in 18 patients (19%), embolization therapy alone in 41 (44%), and both therapies in 7 (8%). The 48 patients treated with embolization required 78 embolization sessions with more than 200 lesions occluded. Complications of treatment included postembolization hemothorax in 1 patient and right-sided hemiparesis in another patient. Follow-up disclosed that 1 patient died from PAVF-related complications. CONCLUSIONS: Among our patients with PAVFs, hereditary hemorrhagic telangiectasia was observed in more than half and neurologic complications in more than one third. Because of the considerable risk of neurologic and other complications, definitive treatment should be considered in patients with PAVFs. Embolization is currently the preferred treatment in most patients. Frequent follow-up of treated patients is necessary because PAVFs tend to increase both in number and in size over time.
BACKGROUND: To determine optimal management of major abdominal arteriovenous fistulae and define factors affecting outcome. METHODS: We reviewed clinical data of 18 patients, 16 males and 2 females, who underwent repair of major abdominal arteriovenous fistulae between 1970 and 1997. RESULTS: Sixteen patients had primary fistula, caused by rupture of an atherosclerotic aortic or aortoiliac aneurysm into the inferior vena cava (IVC), iliac, or left renal vein. Two had secondary, iatrogenic arteriovenous fistulae. Seventeen patients (94%) were symptomatic, 11 (62%) had acute presentation. Fistula was diagnosed preoperatively in 8 (44%). Fistula closure (direct suture 16, patch 1, iliac vein ligation 1) was followed by aortoiliac reconstruction in all patients. Caval clip was placed in 3 patients. Early mortality was 6%; 7 patients had major complications. During follow-up (mean 6.1 years) 2 patients died of causes related to fistula closure. CONCLUSIONS: Rupture of aortoiliac aneurysms into the iliac veins or IVC carries a better prognosis than intraperitoneal, retroperitoneal, or enteric rupture. Although preoperative diagnosis is ideal, a high index of suspicion, careful repair avoiding pulmonary embolization, and blood salvage were all helpful in keeping morbidity and mortality low. Our data suggest that IVC interruption is seldom warranted.
OBJECTIVE: To describe a series of 252 patients with Klippel-Trénaunay syndrome (KTS), a rare congenital malformation characterized by the triad of capillary malformations, atypical varicosities or venous malformations, and bony or soft tissue hypertrophy usually affecting one extremity. MATERIAL AND METHODS: We reviewed the clinical characteristics and findings in 136 female and 116 male patients with KTS who underwent assessment at Mayo Clinic Rochester between January 1956 and January 1995. In addition, management options are discussed. RESULTS: Capillary malformations (port-wine stains) were found in 246 patients (98%), varicosities or venous malformations in 182 (72%), and limb hypertrophy in 170 (67%). All three features of KTS were present in 159 patients (63%), and 93 (37%) had two of the three features. Atypical veins, including lateral veins and persistent sciatic vein, occurred in 182 patients (72%). Operations performed in 145 patients with KTS included epiphysiodesis, stripping of varicose veins or venous malformations, excision of vascular malformations, amputations, and debulking procedures. CONCLUSION: Most patients with KTS should be managed conservatively. The clearest indication for operation is a leg length discrepancy projected to exceed 2.0 cm at skeletal maturity, which can be treated with epiphysiodesis in the growing child. If a functioning deep vein system is present, removal of symptomatic varicosities or localized superficial venous malformations in selected patients can yield good results.
PURPOSE: Superior vena cava (SVC) reconstructions are rarely performed; therefore the need for surveillance and the results of secondary interventions are unknown. METHODS: During a 14-year period 19 patients (11 male, 8 female; mean age 41.9 years, range 8 to 69 years) underwent SVC reconstruction for symptomatic nonmalignant disease. Causes included mediastinal fibrosis (n = 12), indwelling foreign bodies (n = 4), idiopathic thrombosis (n = 2), and antithrombin III deficiency (n = 1). Spiral saphenous vein graft (n = 14), polytetrafluoroethylene (n = 4), or human allograft (n = 1) was implanted. RESULTS: No early death or pulmonary embolism occurred. Four early graft stenoses or thromboses (spiral saphenous vein graft, n = 2, polytetrafluoroethylene, n = 2) required thrombectomy, with success in three. During a mean follow-up of 49.5 months (range, 4.7 to 137 months), 95 imaging studies were performed (average, five per patient; range, one to 10 studies). Venography detected mild or moderate graft stenosis in seven patients; two progressed to severe stenosis. Two additional grafts developed early into severe stenosis. Four of 19 grafts occluded during follow-up (two polytetrafluoroethylene, two spiral saphenous vein graft). Computed tomography failed to identify stenosis in two grafts, magnetic resonance imaging failed to confirm one stenosis and one graft occlusion, and duplex scanning was inconclusive on graft patency in 10 patients. Angioplasty was performed in all four patients with severe stenosis, with simultaneous placement of Wallstents in two. One of the Wallstents occluded at 9 months. Repeat percutaneous transluminal angioplasty was necessary in two patients, with placement of Palmaz stents in one. Only one graft occlusion and one severe graft stenosis occurred beyond 1 year. The primary, primary-assisted, and secondary patency rates were 61%, 78%, and 83% at 1 year and 53%, 70%, and 74% at 5 years, respectively. CONCLUSION: Long-term secondary patency rates justify SVC grafting for benign disease. Postoperative surveillance with contrast venography is indicated in the first year to detect graft problems. Endovascular techniques may salvage and improve the patency of SVC grafts.
OBJECTIVE: To analyze the clinical characteristics, laboratory features, and outcome in five patients who had biochemically proven adrenal insufficiency attributable to pathologically confirmed non-Hodgkin's lymphoma (NHL). MATERIAL AND METHODS: We retrospectively reviewed the medical records of all patients at Mayo Clinic Rochester during the period from 1976 to 1994 to identify those with both NHL, as listed in the surgical pathology tissue registry, and adrenal insufficiency. Histologically, the patients were classified on the basis of the working formulation and the revised European-American lymphoma classification. RESULTS: Three patients had diffuse large cell NHL, one patient had small noncleaved NHL, and one patient had cutaneous T-cell NHL. All five patients had stage IV disease. Adrenal insufficiency was confirmed by morning and evening determinations of serum cortisol levels and cosyntropin stimulation tests. All patients demonstrated loss of circadian rhythm. The median age of the patients was 77 years (range, 60 to 89). Three of the five patients died without treatment from 5 to 22 days after assessment. One patient died of a cerebrovascular accident. Despite initiation of chemotherapy, two patients died of progressive NHL at 7 weeks and 7 months. CONCLUSION: In our experience, biochemically proven adrenal insufficiency in patients with NHL is a manifestation of clinically advanced disease in elderly patients. A stepwise diagnostic approach is critical for the appropriate management of such patients.
PURPOSE: This study was designed to identify significant differences in the clinical and radiologic characteristics and outcome between patients with inflammatory and noninflammatory abdominal aortic aneurysms (AAAs). METHODS: We reviewed 29 consecutive patients who underwent repair of an inflammatory AAA between 1985 and 1994. This group was matched in a case-control fashion by date of surgery and by the performing surgeon to a group of 58 patients who underwent repair of noninflammatory AAAs. RESULTS: The two groups had comparable characteristics of age, gender, and cardiovascular risk factors. Patients with inflammatory AAAs were significantly more symptomatic than those with noninflammatory AAAs (93% vs 9%, p < 0.001), were more likely to have a family history of aneurysms (17% vs 1.5%, p = 0.007), and tended to be current smokers (45% vs 24%, p = 0.049). The most significant laboratory difference was an elevated sedimentation rate in patients with inflammatory AAAs (mean, 53 mm/hr vs 12 mm/hr, p < 0.00001). Inflammatory AAAs also were significantly larger than noninflammatory AAAs at presentation (6.8 cm vs 5.9 cm, p < 0.05). Although operative mortality was low in both groups, patients with an inflammatory AAA tended to have higher morbidity, including sepsis (p < 0.01) and renal failure (p = 0.04). Five-year survival rates, however, were similar for the two groups (79% for inflammatory and 83% for noninflammatory AAAs). On follow-up computed tomographic scans, the retroperitoneal inflammatory process resolved completely in 53% of the patients, but 47% of patients had persistent inflammation that involved the ureters in 32% and resulted in long-term solitary or bilateral renal atrophy in 47%. CONCLUSIONS: This case-control study provides preliminary evidence that inflammatory AAAs may have a relatively strong familial connection and that current smoking may play an important role in the inflammatory response. The study also documents that persistent retroperitoneal inflammation may be more prevalent than has been previously reported, and stresses the need for an improved understanding of the pathogenesis and long-term management of inflammatory AAAs.
PURPOSE: Persistent sciatic vein (PSV) is a rare anomaly most often associated with Klippel-Trenaunay Syndrome (KTS). Magnetic resonance imaging (MRI) and extended use of phlebography have increased the frequency of diagnoses. To evaluate our experience, we reviewed patients in whom PSV was diagnosed at our institution. METHODS: MRIs and phlebograms of all patients with KTS seen since 1985 were reviewed, and patients with PSV were identified. RESULTS: Forty-one of 186 patients with KTS underwent MRI. PSV was diagnosed in 20 of the 41 (48.8%). In addition, one other patient without KTS had PSV. Thirteen patients (61.9%) were female. Patient age ranged from 5 to 71 years, with a median age of 22 years. PSVs were present in the entire thigh and buttock of eight patients (38.1%), the upper thigh and buttock of six patients (28.6%), and the lower thigh of seven patients (33.3%). Six patients (28.6%) had anorectal arteriovenous malformations with heavy bleeding. Five patients (23.8%) had pulmonary embolization. Two patients (9.5%) died. Amputation was required in one (4.8%). Nineteen patients (90.5%) underwent no specific surgery for PSV. Two patients (9.5%) underwent successful excision of PSVs. CONCLUSIONS: Excision of PSV appears to be rarely indicated. It may be indicated for localized symptoms in patients whose condition and anatomy permit. PSV may be a marker for patients with more extensive arteriovenous malformations and for those at high risk for rectal bleeding and pulmonary embolization. Prognosis is related to the associated vascular malformations. MRI and extended use of phlebography should increase the frequency of diagnoses. Treatment rationales should evolve.
Recent technical advances in CT have led to the ability to scan a volume in a shorter period with optimal contrast opacification of blood vessels, including the pulmonary arteries. Initially, there were isolated instances of an accidental detection of a filling defect because of pulmonary embolus in the pulmonary arteries. Gradually, directed examinations were introduced to diagnose or exclude pulmonary embolus. These examinations were successful. Radiologists and clinicians now are turning to fast CT for this purpose for a variety of reasons, including the proven accuracy and reliability of the method and the relative deficiencies of traditional noninvasive methods. Accurate interpretation of CT scans for possible pulmonary embolus depends on the ability to conduct a high-quality examination and to recognize the spectrum of findings for both acute and chronic emboli. This article reviews the history of fast CT pulmonary angiography, and it presents both technical and diagnostic information germaine to the performance of this technique.
The effect of renal artery stenosis on intrarenal perfusion and volume in renovascular hypertensive patients is unclear. Alterations in these attributes may ultimately be involved in deterioration of renal function. We measured whole kidney, cortical, and medullary perfusion and volume with electron beam computed tomography (EBCT) in 33 hypertensive patients, with well-preserved renal function, scheduled for renal angiography. EBCT-derived whole kidney perfusion was lower in patients with atherosclerotic renal artery stenosis (RAS; N = 20) than in fibromuscular dysplasia (FMD; N = 10) or essential hypertension (N = 28; P < 0.05), as was cortical perfusion (2.44 +/- 0.16 vs. 3.26 +/- 0.17 and 3.07 +/- 0.09 ml/min/cc tissue, respectively, P < 0.005), but medullary perfusion was similar. Whole kidney, cortical, and medullary perfusion correlated inversely with degree of stenosis in FMD, but not in atherosclerotic RAS. Renal volumes were similar. These results demonstrate that, in contrast to patients with FMD, in patients with atherosclerotic RAS the decrease in cortical perfusion is not directly related to the degree of stenosis in the main renal artery. Factors other than the stenosis itself may play a role in the pathophysiology of atherosclerotic RAS and associated renal failure.
Intraluminal airway pressure and pharyngeal muscle activity are widely recognized as major determinants of the size and collapsibility of the upper airway. In addition, changes in the volume or pressure of tissue surrounding the pharyngeal airway may significantly influence its size. The present study used fast computed tomography (CT) to determine the effects of changes in central venous pressure (CVP) on upper airway size. Ten awake male patients with obstructive sleep apnea (OSA) were studied. Scans were performed at functional residual capacity (FRC) and at the end of a tidal inspiration (VTei) under three conditions of CVP: (1) at baseline (CVP nl) with patients lying supine; (2) at decreased CVP (CVP-) by inflating blood pressure cuffs to 40 mm Hg on both legs; and (3) at increased CVP (CVP+) by elevating both legs to 33 degrees. At FRC, changes in CVP had no significant effect on either mean or minimum cross-sectional area (CSA) of the upper airway. In contrast, an analysis of variance (ANOVA) indicated that alterations in CVP were associated with changes in mean CSA (p = 0.03) and to a lesser extent in minimum CSA (p = 0.07) at VTei. With the legs elevated (CVP+), neither mean nor minimum CSA showed any significant change with tidal breathing. However, after leg-cuff inflation (CVP-), highly significant increases in both mean (163 +/- 22 to 218 +/- 19 mm2, p = 0.001) and minimum (48 +/- 8 to 85 +/- 12 mm2, p = 0.02) CSA were detected. Changes in mean and minimum CSA with tidal breathing at baseline (CVP nl) were intermediate. These results indicate that changes in CVP significantly alter the response of the upper airway to tidal breathing. They further suggest that increases in upper airway size with tidal breathing may be related to reduction in venous blood volume in pharyngeal and neck tissues as the generation of negative intrathoracic pressure during inspiration increases venous return to the chest.
OBJECTIVE: To document a cumulative experience with removal of the Telectronics 330-801 Accufix atrial lead after it was withdrawn from the market. DESIGN: We reviewed our results with 96 attempted lead extraction procedures through Dec. 1, 1995. MATERIAL AND METHODS: All patients underwent preoperative assessment, including fluoroscopic screening of the lead. Patients had blood typing and screening done before the extraction procedure, and extractions were performed with cardiac surgical intervention available. Pacing dependence was assessed to determine the need for temporary pacing. RESULTS: The mean patient age was 65.7 +/- 1.6 years and the mean duration of lead implantation was 31.0 +/- 1.4 months. Of the 96 lead extractions attempted, 94 were successful. Of the 96 cases, the retention wires were normal in 29, fractured without protrusion in 34, and fractured with protrusion in 33. Fifty-three leads were removed with use of simple traction only, and seven leads were removed by using a locking stylet and telescoping sheaths. The Cook workstation was used in the removal of 32 leads through the femoral vein; in 1 of these 32 patients, the retention wire was removed before lead extraction. The retention wire was removed but the lead was left intact in one patient. One lead was removed during an opertive maze procedure. Associated complications were minimal. CONCLUSION: Although lead extraction is a potentially fatal procedure, the Telectronics 330-801 Accufix atrial lead can be extracted safely with minimal morbidity when performed by experienced personnel.