Toward robot-assisted vascular microsurgery in the retina

BACKGROUND: Experimental protocol in our laboratory routinely requires the precise placement of instruments at, or near, the retina. Although manipulators for placing an instrument within the eye presently exist, none of the designs were satisfactory due to limitations on size, accuracy and operability. To overcome these limitations, we have developed a novel six degree of freedom manipulator designed specifically for retinal microsurgery. METHODS: The manipulator is parallel in structure and provides submicrometer positioning of an instrument within the constrained environment of the eye. The position of an instrument attached to the manipulator is commanded by the operator using a hand-held trackball. A computer controller interprets the trackball input and moves the manipulator in an intuitive manner according to mathematically constrained modes of operation. RESULTS: Over 50 retinal vessels in the live, anesthetized cat have been successfully cannulated for pressure measurement and drug injection using the described manipulator and micropuncture techniques. The targeted vessels ranged in internal diameter from 20 to 130 microns. CONCLUSION: This device has applications in microsurgery where tremor and fatigue limit the performance of an unaided hand and where mechanically constrained manipulators are inappropriate due to size and operative constraints.     

Arterial fasciocutaneous vascular territories of the lower leg

The purpose of this study was to analyze the fasciocutaneous arterial circulation of the lower extremity to provide a quantitative guide to design reliable fasciocutaneous flaps. Thirty-one fresh cadaver limbs were studied using the techniques of dissection of latex injected specimens, selective ink injections, and barium latex radiographs. Fasciocutaneous perforator locations were recorded according to fascial septum of origin and distance relative to bony landmarks between the knee and the ankle. Selective ink injections of the trifurcation vessels identified four anterior tibial, three peroneal, and three posterior tibial fasciocutaneous territories. Although perforator site locations were randomly distributed along the trifurcation vessel within any vascular territory, the separate cutaneous regions that make up the fasciocutaneous territories occur in predictable locations with a measurable standard deviation. The transverse section radiographs confirmed the transverse dimensions of the vascular territories. Additionally, the summation of any two vascular territories calculated from the anatomical data conforms to the clinically observed 2.5:1 to 3:1 length-to-width ratios for fasciocutaneous flap viability as reported by Ponten and by Barclay et al. This study provides a quantitative anatomical framework using primary fasciocutaneous vascular territories to design potentially reliable fasciocutaneous flaps in the lower extremity.     

Congenital anomalies and vascular birthmarks of the lower extremities

MR imaging is an invaluable tool for the evaluation of congenital abnormalities and vascular birthmarks of the extremities in children. These abnormalities of the immature musculoskeletal system are often underestimated by radiography. MR imaging is useful for diagnosis, assisting in therapy, showing response to treatment, and determining prognosis. Localized and generalized abnormalities of the lower extremities and issues pertinent to their MR imaging are illustrated in this article.     

Arterial vascular remodeling: the endothelial cell''s central role

As a measurement of the level of anxiety in psychiatric outpatients with anxiety, we determined the saliva level of free 3-methoxy-4-hydroxyphenyleglycol (MHPG) using gas chromatography- mass spectrometry and scored the levels of anxiety with the Hamilton Anxiety Scale (HAS) in patients, before and after drug treatment with alprazolam for 1 week. The saliva level of free-MHPG at first visit to hospital was significantly higher than that of control individuals and disease control individuals and was reduced by alprazolam treatment for 1 week. There was no correlation between MHPG level and the HAS score at the first hospital visit. The MHPG levels after treatment correlated with the HAS scores. The reduction of the anxiety level as scored by the HAS correlated with the reduction of MHPG level. These results indicate that the free saliva MHPG level may be a useful indicator for assessing not only the level of anxiety, but also the response to drug treatment for anxiety in these patients.     

Arterial vascular injuries in hip prosthesis implantation

Implantation of total endoprosthesis (TEP) is an established method for the operative therapy of acute and chronic hip dysfunction. Beside septic complications iatrogenic injuries of the vascular system regularly occur. Immediate and adequate therapy is necessary in order to prevent loss of an extremity or even patients death. We present three patients with major vascular injuries during hip joint operations. In two patients was the external iliac artery and in one the femoral common artery injured. The cases were managed with PTFE- or Dacron-interposition. The problem of vascular injuries associated with the implantation of total hip joint endoprosthesis will be discussed and the avoidable of most vascular lesions is underlined.     

Arterial vascular lesions after total hip joint replacement

We report on three arterial thromboses of the external iliac artery following total hip replacement. As a result of implanted cement/spongiosa or protrusion of the acetabular component, the iliac vessels were compressed. Furthermore, we report about one intraoperative arterial vessel lesion in a 65-year-old patient during a revision operation. We recommend that in case of acute ischemic syndromes of lower limbs following total hip replacement, an angiography should be performed in order to exclude an extravascular cause of thrombosis. For therapy in those cases extra-anatomic bypasses should be preferred to thrombectomies.     

Sternal cleft associated with vascular anomalies and micrognathia

Three hundred and seventy-five acanthocephalans, Moniliformis clarki, were removed from the small and large intestines of a gray squirrel from Arkansas County, Arkansas (USA). This is the first report of M. clarki from Arkansas. Enteric lesions, including distension, perforating ulcers, enteritis, crypt hypertrophy, goblet cell hyperplasia, and occlusions of the intestinal tract were observed, indicating the pathogenic potential of this parasite.     

Arterial anatomy of the oral cavity: an analysis of vascular territories

Knowledge of the specific cutaneous or surface regions supplied by constant named arterial sources has allowed for increasing clinical application of flap transfers of tissue. Despite the routine use of intraoral flaps for reconstruction of congenital or acquired defects of the oral cavity and pharynx, no previous investigation has centered on understanding the surface or mucosal arterial territories of the oral cavity. In a cadaver study, six mucosal territories of the intraoral cavity were defined using selective ink and lead oxide injections through named arteries. The anatomical boundaries of these territories are predictable and constant in location for different cadavers. The six contiguous territories are based on the buccal, labial, inferior alveolar, ascending palatine, ascending pharyngeal, and lingual arteries. This study supports the safe vascular basis of existing clinical procedures of the intraoral cavity and may have implications for the design of new intraoral reconstructive procedures.     

Localization of vascular endothelial growth factor in human retina and choroid

OBJECTIVE: To examine the distribution and relative levels of vascular endothelial growth factor (VEGF) in the nondiabetic and preproliferative diabetic human retina and choroid. METHODS: Immunohistochemical localization was performed on frozen sections from cryopreserved postmortem human tissue using a polyclonal antibody against VEGF and a streptavidin peroxidase system. Eyes from 5 subjects without diabetes and 8 subjects with diabetes were examined and analyzed using a 7-point immunohistochemical grading system. RESULTS: In subjects without diabetes, weak or no VEGF immunoreactivity was associated with retinal blood vessels. In subjects with diabetes, we found significantly increased immunoreactivity in the retinal vascular endothelium and blood vessel walls. Vascular endothelial growth factor immunoreactivity was also associated with intravascular leukocytes in subjects with and without diabetes. In the choroid of subjects without diabetes, immunoreactivity was almost exclusively associated with intravascular leukocytes, whereas in diabetic subjects, immunoreactivity was localized within choriocapillaris endothelium, choroidal neovascular endothelium, and migrating retinal pigment epithelium cells. CONCLUSIONS: The observed increase in VEGF immunoreactivity in the diabetic retina and choroid suggests that VEGF may contribute to 2 well-documented events during retinopathy: increased vascular permeability and angiogenesis.     

Open foramen ovale in patients with arterial vascular occlusions of the retina and optic nerve

BACKGROUND: We examined the frequency and significance of persistent foramen ovale (PFO) in patients with ocular circulatory disturbance. PATIENTS AND METHODS: Forty patients with acute arterial occlusions of the posterior bulb segment were investigated by means of transthoracic and transesophageal echocardiography (TEE). The parallel presence of cerebral ischemia was clarified on the basis of existing CCT findings and by additional HMPAO-SPECT investigation. RESULTS: PFO was identified in nine of the patients investigated. The probability of paradoxical embolism arises from further findings: eight of those with PFO (89%) showed echocardiographic signs of right heart strain, indicating previous pulmonary embolism, compared with only three of those without PFO (10%). Five of those with PFO showed a potential source of embolism, two of them with phlebothromboses in their clinical history and three with additional atrial septal aneurysm. Cardiovascular risk factors were prevalent in the group without PFO. Both groups had a mean age of approximately 60 years. Signs of cerebral ischemia were present in the SPECT or CT findings for four of the patients with PFO and nine of those without. CONCLUSIONS: From our findings, it appears highly probable that ocular arterial occlusion is caused by paradoxical embolism. PFO should be taken into account in establishing a diagnosis, including diagnosis in elderly patients.     

Radiologic evaluation of the jugular foramen. Anatomy, vascular variants, anomalies, and tumors

The jugular foramen varies considerably in size and shape, along with the jugular vein. The foramen is traversed by several vessels and nerves. CT, in various section planes, demonstrates the bone anatomy optimally, whereas MR (including MR angiography) reveals the vascular and soft tissue structures to best advantage. A diverse group of vascular anomalies originate in the foramen and adjacent carotid canal that must be differentiated from tumors. The most common tumor within the jugular foramen is the hypervascular glomus jugulare tumor followed by neurogenic tumors, predominantly the schwannoma. Less common lesions comprise meningioma, hemangiopericytoma, chondrosarcoma, and plasmacytoma. Metastases and malignant tumors arising in adjacent anatomic structures (nasopharynx, parotid, and temporal bone), in advanced stages, may spread to the jugular foramen. Endolymphatic sac tumors arise at the posterior medial aspect of the petrous bone and frequently extend to the jugular foramen. Irregular lytic bone destruction, with enlargement and hypervascularity, demonstrated by CT and MR imaging, are characteristic for glomus jugulare tumors. Benign tumors, most commonly the jugular foramen schwannoma, display an enlarged jugular foramen with well-defined bone margins.     

Gastrointestinal manifestations of vascular anomalies in childhood: varied etiologies require multiple therapeutic modalities

BACKGROUND/PURPOSE: Vascular anomalies, including hemangiomas and vascular malformations afford complex diagnostic and therapeutic challenges when gastrointestinal (GI) manifestations are present. METHODS: Twenty-one patients evaluated or treated in our Vascular Anomalies Program from 1993 through 1997 were reviewed retrospectively with regard to presentation, treatment modalities, and outcome. RESULTS: Four patients had hemangiomas, and 17 had various vascular malformations. GI symptoms began in infancy or early childhood in all patients. Manifestations included GI bleeding (n = 15), obstruction (n = 2), diarrhea (n = 2), ascites (n = 2), pain (n = 1), emesis (n = 1), ileo-ileal intussusception (n = 1), protein-losing enteropathy (n = 1), and hypersplenism (n = 1). Four patients had proven portal hypertension. Fourteen had associated musculoskeletal or cutaneous lesions. Congestive heart failure, partial anomalous pulmonary venous return, pulmonary edema, and pleural or pericardial effusion occurred in one patient each. Bleeding was the most common symptom of both hemangiomas and malformations. Of four patients with hemangiomas, three were treated with corticosteroids or interferon. Endoscopic banding and embolization of an associated arterioportal hepatic shunt were each used in one patient. One patient died. The malformations were treated with resection (n = 8), endoscopic banding or sclerosis (n = 7), percutaneous or intraoperative sclerosis (n = 5), embolization or device interruption (n = 3), and portosystemic shunt (n = 2). GI symptoms were ameliorated in 12 patients with malformation, improved in two, unchanged in two, and one died after prolonged palliation. CONCLUSIONS: Vascular anomalies with gastrointestinal manifestations are heterogeneous in their presentation and type. Although bleeding is the most common symptom of both hemangiomas and vascular malformations, treatment differs. Pharmacological angiogenesis inhibition is the mainstay of hemangioma therapy. Resection, endoscopic or radiologic vascular obliteration, and portal decompression are important in treating vascular malformations. An individualized and interdisciplinary approach is often required to successfully diagnose and treat these complex lesions.     

Arterial bullet embolism resulting in delayed vascular insufficiency: a rationale for mandatory extraction

This paper reports a case of migrating intravascular bullet embolus that initially produced no symptoms but resulted in an above-knee amputation 14 months after its entry into a peripheral artery. The missile entered through a penetrating gunshot wound to the abdominal aorta and later became lodged in the left popliteal artery. However, the bullet fragment migrated further into the posterior tibial artery with consequent vascular insufficiency requiring a supracondylar amputation of the left lower extremity 14 months later. Emphasis is placed on the need for a high index of suspicion for bullet embolism, aggressive search for any bullets unaccounted for, and early surgical removal of all confirmed arterial emboli.     

Arterial injuries of the extremities

Fifty-eight patients with arterial injuries of the extremities were treated during the past 8 years. Fifty-one had acute injuries and seven had nonacute injuries. Blunt trauma or shotgun wounds caused 74% of the injuries, and 55% were associated with skeletal trauma. All the acute injuries endangered the limb; the average ischemic time was 8.5 hours. Brachial, popliteal, and superficial femoral arterial injuries were seen most frequently. Repair was accomplished with autogenous saphenous vein grafts in 47% and end-to-end anastomosis in 41%. Six patients died, four due to injuries of other organs. The most alarming complication of arterial repair was secondary hemorrhage which occurred in three patients and was caused by local infection. Six patients (13.3% required amputations; the highest number (three) after injuries of the popliteal artery. The injuries leading to amputations had associated prolonged ischemia, severity of injury, and associated venous, soft tissue, and skeletal injury. The nonacute injuries were in the form of false aneurysms, pulsating hematomas, AV fistula, and delayed bleeding. These were easily managed without any significant complication.     

Mapping the human retina

The new therapeutic method of scotoma-based photocoagulation (SBP) developed at the Vienna Eye Clinic for diagnosis and treatment of age-related macular degeneration requires retinal maps from scanning laser ophthalmoscope images. This paper describes in detail all necessary image analysis steps for map generation. A prototype software system for fully automatic map generation has been implemented and tested on a representative dataset selected from a clinical study with 50 patients. The map required for the SBP treatment can be reliably extracted in all cases. Thus, algorithms presented in this paper should be directly applicable in daily clinical routine without major modifications.     

Congenital anomalies of the hand

The toxicokinetics of the four stereoisomers of the nerve agent C(+/-)P(+/-)-soman was analysed in cerebrospinal fluid (CSF) and blood in anaesthetized, spontaneously breathing pigs during a 90-min period after injection of soman. The pigs were challenged with different intravenous (i.v.) doses of C(+/-)P(+/-)-soman corresponding to 0.75-3.0 LD50 (4.5, 9.0 and 18 microg/kg in a bolus injection and 0.45 microg/kg per min as a slow infusion). Artificial ventilatory assistance was given if, after soman intoxication, the respiratory rate decreased below 19 breaths/min. Blood samples were taken from a femoral artery and CSF samples from an intrathecal catheter. The concentrations of the soman isomers were determined by gas chromatography coupled with high resolution mass spectrometry. All four isomers of soman were detected in both blood and CSF samples. The relatively non-toxic C(+/-)P(+) isomers disappeared from the blood stream and CSF within the first minute, whereas the levels of the highly toxic C(+/-)P(-) isomers could be followed for longer, depending on the dose. Concurrently with the soman analyses in blood and CSF, cholinesterase (ChE) activity and cardiopulmonary parameters were measured. C(+/-)P(-) isomers showed approx. 100% bioavailability in CSF when C(+/-)P(+/-)-soman was given i.v. as a bolus injection. In contrast, C(+/-)P(-) isomers displayed only 30% bioavailability in CSF after slow i.v. infusion of soman. The ChE activity in blood decreased below 20% of baseline in all groups of pigs irrespective of the soman dose. The effect of soman intoxication on the respiratory rate, however, seems to be dose-dependent and the reason for ventilatory failure and death. Artificial ventilation resulted in survival of the pigs for the time-period studied.