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Biomedical subjects

G H White

Publications and source records attributed to G H White.

At least 19 recordsLinked to original sources
PubMed1992

A new classification of hepatic territories using intraoperative ultrasound.

Intraoperative ultrasonography is now established as the most accurate technique for detecting and localizing hepatic tumors, be they primary or metastatic. A major problem is the accurate placement of any lesions found by intraoperative ultrasound and, hence, the correlation of the lesions found by ultrasound to the current classification of hepatic segments and to lesions seen by other imaging techniques. This paper outlines an objective and reproducible method of mapping hepatic lesions into territories defined solely by the major hepatic veins and their tributaries. It is a simple technique that can be readily used by any surgeon, which accurately determines the presence, number, size, and site of hepatic metastases.

Humans↗
PubMed1992

Angioscopy.

Endoscopy of the vascular system has evolved over recent years from an experimental procedure to a sophisticated diagnostic and therapeutic technique for surgical or percutaneous interventions of the peripheral vascular system. Particularly in procedures involving remote instrumentation of arteries, the angioscope provides a method of controlled guidance and a monitor of the effects of the various instruments on the vessel wall and allows immediate assessment of results. Angioscopic examination reveals the extent of intimal injury after angioplasty, in situ vein preparation, trauma, and thrombectomy and gives insights into the mechanisms and effects of endovascular devices.

Aged↗
PubMed1992

Bilateral mycotic axillary artery false aneurysms in an intravenous drug user: unsuspected broken needle-tips pose a risk to the treating personnel.

Mycotic false aneurysms due to local arterial injury from attempted intravenous injections in drug addicts are increasing in frequency. The high incidence of HIV and hepatitis B virus in parenteral drug users may present a considerable risk to the treating personnel. This paper reports the unsuspected presence of broken needle-tips in the subcutaneous tissues of an intravenous drug abuser, in association with bilateral mycotic aneurysms of the axillary arteries. Broken needle-tips have the potential to cause needlestick injury to the operating team and the nursing staff, with the associated risk of transmission of HIV and hepatitis B virus infection. The presence of broken needle-tips should be suspected in drug users presenting with false aneurysms associated with local arterial injection injury and a specific history of needle-breakage should be sought. Preoperative plain radiographs should be performed of the planned operative field to exclude the presence of such needle-tips. Any soft tissue swelling in the vicinity of a major artery in an intravenous drug abuser should be suspected of being a false aneurysm until proven otherwise and should prompt immediate referral to a vascular surgeon for investigation and management.

Adult↗
PubMed1991

Bench repair of complex renal arterial lesions.

Between 1968 and 1989, 160 patients underwent aortorenal bypass for renovascular hypertension. During the same interval, 13 patients had ex-vivo bench repair of complex renal arterial pathology. There were eight men and five women, with a mean age of 36 years. Twelve of the 13 patients had fibromuscular disease; one had atherosclerosis. Twelve patients had renovascular hypertension with complex stenotic disease beyond the main renal artery. Seven of these also had an associated renal aneurysm as did the sole normotensive patient. Saphenous vein patch or bypass were used to correct stenotic segments in four patients, while the remaining nine patients had excision of stenotic or aneurysmal segments with primary arterial anastomosis. There were no deaths in the series. One kidney was lost because of arterial thrombosis. One patient required reoperation to control postoperative bleeding. Nine of the 12 patients with renovascular hypertension were normotensive off medication, and three were improved, with reduced medication controlling their blood pressure. Ureteric obstruction occurred in two patients; this settled spontaneously in one patient and was corrected by reoperation in the other. From this experience, we conclude that bench repair is a safe and effective way to maximize salvage of kidneys affected by complex arterial pathology.

Adult↗
PubMed1991

Laser angioplasty of the iliac arteries.

Laser-assisted balloon angioplasty has the potential to reduce mortality and morbidity by replacing aorto-femoral bypass operations in patients with occlusion of the iliac arteries. We present our early experience with 16 patients undergoing this procedure, using a Cardiolase neodymium:yttrium aluminum garnet (Nd:YAG) laser in the operating room. Initial recanalization was achieved in 14 of the 16 patients. Early re-occlusion occurred in 4 patients, one of whom had a successful repeat laser angioplasty. This patient, together with the remaining 10 patients with successful initial recanalization remain patent at a mean follow-up period of 10 months. There were no deaths or chest complications. Angiographically demonstrated arterial perforation occurred in 2 patients, neither of whom required operation on the perforated segment. We conclude that recanalization of the iliac arteries is possible and safe. The procedure is unlikely to replace aorto-femoral bypass until the proportion of early failures is reduced. This may require larger probes or the immediate placement of intra-arterial stents following laser angioplasty.

Aged↗
PubMed1991

Assessing acute parathyroid responsiveness in hemodialysis patients by measuring intact parathyrin in pre- and post-dialysis serum.

We measured pre- and post-dialysis concentrations of ionized calcium (iCa) in whole blood, total calcium (tCa) in plasma, and intact parathyrin (PTH) in serum of 19 patients undergoing maintenance hemodialysis. Plasma tCa was inappropriately increased relative to iCa in 63% of the specimens; the iCa correlated with the PTH concentration in 12 of 19 pre-dialysis specimens, whereas tCa correlated with PTH in only five patients. During dialysis, 16 patients had analytically significant changes in iCa (i.e., exceeded the analytical imprecision of 0.04 mmol/L). Pre- and post-dialysis concentrations of PTH were normal in six patients, four of whom showed a detectable response to changes in iCa. Ten patients had increased PTH in at least one specimen; of these, eight had responsive parathyroid glands. Five of the 16 patients had an increased set point for calcium. The minimal PTH responses of two patients suggested refractory hyperparathyroidism. We conclude that routine estimation of iCa, rather than tCa, in dialysis patients markedly improves the identification of patients at risk for secondary hyperparathyroidism, and that measurement of intact PTH in pre- and post-dialysis serum offers a simple means of assessing parathyroid responsiveness in dialysis patients.

Calcium↗
PubMed1990

Exertional disruption of axillofemoral graft anastomosis. 'The axillary pullout syndrome'.

Five cases of exertional disruption of the axillary anastomosis occurred at intervals of 13 to 30 days after axillofemoral polytef (polytetrafluoroethylene [PTFE]) graft insertion. Graft evulsion was preceded by effort and heralded by axillary pain, an expanding hematoma, and a pseudoaneurysm formation. Proximal control of the subclavian artery by a supraclavicular approach or balloon allowed safe wound exploration. Successful reconstruction required lengthening of the graft or replacement. Secondary disruption occurred with simple repair. Although temporary postoperative brachial plexus neuropathy was common, no significant hand ischemia was noted. Twenty-two reports of axillary anastomotic disruption were made to the Food and Drug Administration, Washington, DC, during a 2-year period, and one manufacturer of polytef grafts provided data on 10 reports received throughout 7 years. Surface anatomy measurements in 20 control patients demonstrated that arm abduction and lateral flexion of the body increased the distance between the axillary and femoral arteries by a mean of 15.5%. Similar measurements taken from the proximal axillary artery showed a mean length increase of less than 10%. This complication may be avoided by inserting the polytef graft with several centimeters of excess length and positioning the axillary anastomosis medial to the pectoralis minor muscle.

Adult↗
PubMed1990

Proximal percutaneous balloon angioplasty and distal bypass for multilevel arterial occlusion. Veterans Administration Cooperative Study No. 199.

Multiple sites of atherosclerotic occlusion in high risk patients may be treated by angioplasty of the iliac obstruction and distal reconstruction. We report 18 male patients with symptomatic peripheral vascular disease in whom proximal iliac percutaneous transluminal angioplasty was combined with femoropopliteal bypass (11), femorotibial bypass (2), or femorofemoral bypass (5). There were no operative deaths. The pretreatment ankle brachial index of 0.40 +/- 0.04 was increased to 0.64 +/- 0.04 by discharge (p = 0.0001), and remained significantly increased through 27 months (0.65 +/- 0.07) (p = 0.0001). During the follow-up period of 2-57 (mean 27 months) one dilated iliac artery required repeated percutaneous transluminal angioplasty and revision of the femoropopliteal bypass at three months. Two late amputations of study limbs occurred at two years and three years due to progression of distal disease in the infrapopliteal segment. Four patients died during the follow-up period of ischemic heart disease (3) and lung carcinoma (1). Life table analysis shows a 76% success rate for the combined procedures at two years. In selected, high risk patients, proximal iliac dilatation and distal bypass is an acceptable alternative reconstruction for multilevel occlusion.

Aged↗
PubMed1990

Intraluminal vascular ultrasound: preliminary report of dimensional and morphologic accuracy.

The role of intraluminal ultrasound for diagnosis and monitoring treatment of vascular disease has yet to be defined. This study evaluated the dimensional precision and morphologic accuracy of an intraluminal ultrasound system which consists of a 5.5 French external diameter ultrasonic catheter with a central lumen for passage of a guidewire. Ultrasound images from five in-vitro human and three porcine arterial segments and two in-vivo arteriosclerotic canine arteries were compared to dimensions obtained from arteriograms and from sections of the specimens. Each gross and histological specimen and ultrasound image was scaled, photographed and enlarged up to 20 times and measured for vessel intraluminal and adventitial or outer diameter and wall thickness. Intraluminal and outer diameters and wall thickness from normal in-vitro specimens correlated significantly with dimensions obtained from histologic specimens (r = 0.99, p less than 0.005 for internal and outer diameters and r = 0.73, p less than 0.005 for wall thickness). The mean differences of luminal diameters measured from the vessels supported within a silicone rubber mold was 0.05 +/- 0.09 mm (n = 20). Diameters of outer diameter and wall thickness were less reliably defined, the average margin of error being 0.49 +/- 0.39 mm and 0.29 +/- 0.26 mm, respectively. The mean difference between in-vivo ultrasound and arteriographic diameters was 0.61 +/- 0.38 mm (n = 12). Correlation of luminal diameters between ultrasound and arteriogram was significant (r = 0.76, p less than 0.02). The ultrasound images also differentiated a laminated appearance of normal vessel anatomy from non-uniform or dense signals seen in atherosclerotic lesions.(ABSTRACT TRUNCATED AT 250 WORDS)

Angiography↗
PubMed1990

Endoscopic intravascular surgery removes intraluminal flaps, dissections, and thrombus.

Over the last 3 years angioscopic techniques have been used to guide intraluminal instrumentation in 73 patients undergoing thrombectomy, nine patients with vascular trauma, and 32 patients during laser angioplasty and balloon dilation. After balloon-catheter thromboembolectomy residual, occlusive thrombi tightly adherent to the arterial wall were removed with flexible biopsy forceps in 13 of 73 (18%) patients; underlying intimal flaps were removed in another four. In nine patients traumatic intimal defects caused by iatrogenic cannulation injuries (n = 5) or external trauma (n = 4) were managed by thrombectomy followed by complete or partial intravascular removal of the intimal flap (n = 6) or dissection plane (n = 3) with long flexible forceps and rotating brushes. Traumatic intimal defects observed in two additional patients were judged to be too severe for endoscopic manipulation and required immediate bypass grafting. Inspection after angioplasty in 32 patients revealed wall charring and obvious thermal damage after laser procedures in 28 (87%) and plaque cracking, intimal flaps, and fragmentation in 26 (81%). These defects were underestimated on intraoperative angiography. Large flaps and thrombus were removed endoscopically in three. We conclude that angioscopic study reveals the extent of intimal injury and gives insights into mechanisms of instrumentation. Adherent thrombus after embolectomy by balloon catheter and intimal flaps caused by trauma or angioplasty are common and, if severe, can be successfully treated by endoscopic intravascular manipulation in selected patients.

Blood Vessels↗
PubMed1990

A clinical trial of laser thermal angioplasty in patients with advanced peripheral vascular disease.

A 3-year prospective trial of laser thermal-assisted balloon angioplasty in 28 patients included 27 who had advanced peripheral vascular disease (severe tissue loss, gangrene, infection, and rest pain), 7 who were failures of previous therapy (surgery and thrombolysis), and 4 who were high risk for operation (myocardial infarction within 6 weeks and/or ejection fractions of less than or equal to 20%). Laser angioplasty was performed in the operating room via a groin incision by a surgeon-radiologist team. In the 27 patients with advanced peripheral vascular disease (ankle-brachial systolic pressure index [ABI] 0.27 +/- 0.2 in 10 nondiabetic, and 0.46 +/- 0.1 in 17 diabetic patients), recanalization of the native vessel was successful in 16, and patency was restored in 2 chronically occluded polytetrafluorethylene (PTFE) grafts. In these 18 (67%) successfully recanalized patients, however, five amputations were required within 1 month, and another six were needed between 8 and 12 months. Early amputations were caused by a failure of wound healing, even through angioplasty sites were patent. Late amputations were caused by reocclusion of the treated site in five of six patients. In the remaining seven patients in whom laser angioplasty alone was successful, five had healed limbs at 6 to 24 months and two remain incompletely healed but functional. The patency for successful procedures ranged from 48 hours to 25 months (5.6 +/- 6.4 mean months, +/- SD), with cumulative patency by life-table analysis of 55.5% at 3 months, 38.8% at 6 months, and 11.1% at 12 months. There were no procedure-related deaths. Complications included seven arterial wall perforations by the laser probe. We conclude that laser angioplasty has a limited role in advanced peripheral vascular disease but may provide an interval patency, thus allowing postponement of operation for high-risk patients until their medical conditions permits surgery, or to correct local tissue necrosis or infection in the operative field before reconstruction, and to restore patency to thrombosed PTFE grafts.

Aged↗
PubMed1990

Variation in plasma apolipoprotein A-1 and B concentrations following myocardial infarction.

Measurements of plasma apolipoprotein A-1 and B concentrations are increasingly used for the laboratory assessment of risk of coronary artery disease (CAD). This study of 22 patients investigated the response of plasma apolipoprotein A-1 and B levels for up to 20 days following a myocardial infarction. Seven of these patients participated in a clinical trial using the drug Tissue Plasminogen Activator (TPA). We established that, unlike many other plasma proteins, apolipoproteins do not display a classic acute phase response following myocardial infarction, although large variations in plasma apolipoprotein levels were observed in the patients investigated. Our studies also show that the measurement of plasma apolipoproteins A-1 and B to assess future CAD risk in myocardial infarction patients should be deferred for a minimum of at least 14 days post-infarction. No significant difference was observed in the pattern of apolipoprotein response between patients receiving TPA and those not given this drug.

Adult↗
PubMed1990

Intravascular ultrasound: a new potential modality for angioplasty guidance.

Current angioplasty devices are limited by significant rates of arterial perforation and dissection, due to inadequate techniques of guidance, and by restenosis, which may be partly attributed to inadequate debulking of lesions. This paper describes the authors' initial experience in-vitro and in-vivo with intravascular ultrasound as a possible method of enhancing the three-dimensional guidance of devices through atherosclerotic obstructions. Using an in-vitro model they correlated the dimensions and histologic morphology of animal and human arteries with ultrasound images of the specimens. Additional in-vivo evaluations of this technology in canine arteriosclerotic and human atherosclerotic arteries preliminarily support the hypothesis that intravascular ultrasound defines the transmural arterial morphology and may enhance the accuracy of angioplasty procedures. Simultaneous imaging with angioscopy and intravascular ultrasound is demonstrated as a potential method of accurately defining both intraluminal and transmural arterial wall characteristics.

Angioplasty, Balloon↗