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Biomedical subjects

K J Hansen

Publications and source records attributed to K J Hansen.

48 records · Page 3Linked to original sources
PubMed1992

Prevalence of ischemic nephropathy in patients with renal insufficiency.

To estimate its clinically unsuspected prevalence among patients with renal insufficiency, renal duplex sonography (RDS) was used to estimate the presence of critical renal artery stenosis (RAS) in that population. Patients, aged 45 to 75 years, with a serum creatinine of greater than or equal to 2.0 mg% but without dialysis dependence, prior renal transplantation, or prior renal artery surgery were considered for RDS. Fifty-three patients who met criteria for study were randomly selected from the Section of Nephrology clinic files and each patient was contacted both by mail and by telephone. Twenty-five patients agreed to RDS, and renal artery anatomy was determined in 21 patients using standardized RDS techniques. These techniques have demonstrated an overall accuracy of 96 and 97 per cent when compared prospectively to conventional angiography during validity analyses in the authors' center. Results of RDS revealed significant findings in 5 of 21 patients (24%). Three patients demonstrated criteria for ischemic nephropathy (IN): one patient had RAS with contralateral renal artery occlusion confirmed by angiography, while 2 patients demonstrated unilateral RAS. An abdominal aortic aneurysm and unilateral hydronephrosis were discovered in the fourth and fifth patients. Evaluation of patient demographic data and functional parameters as predictors of IN revealed that the duration of renal insufficiency at the time of RDS and extra-renal organ-specific atherosclerotic damage were significantly different between the groups with and without IN. The authors preliminary findings suggest that unsuspected ischemic nephropathy may exist in a significant minority of patients with renal insufficiency.

Age Factors↗
PubMed1991

Evolution of renal insufficiency in ischemic nephropathy.

This retrospective review of data collected during a recent 42-month period from 58 consecutive patients with ischemic nephropathy submitted to operative management in the authors' center was undertaken to report the rate of decline in their renal function during the period before intervention and to examine the impact of operation on their outcome. Based on serum creatinine values, immediate preoperative estimated glomerular filtration rates (EGFR) ranged from 0 to 46 mL/minute (mean, 23.85 +/- 9.76 mL/minute). Eight patients were dialysis dependent or anuric at the time of operation. Patients with at least three sequential measurements for calculations of EGFR changes during the 6 months before operation (n = 50) and the first 12 months after operation (n = 32) were used to describe the preoperative rate of decline in EGFR and the impact of operation on this decrease in the operative survivors. In addition comparative analyses of data from patients with unilateral versus bilateral lesions and patients classified as having improvement in EGFR versus no improvement after operation were performed. Comparison of the immediate preoperative EGFR with the immediate postoperative EGFR for the entire group showed significant improvement in response to operation. Likewise the rate of deterioration in EGFR for the total group was improved after operation. A similar improvement in the rate of deterioration in EGFR was seen in the subgroup of patients who received an immediate improvement in EGFR in response to operation. These data argue that ischemic nephropathy is a rapidly progressive form of renal insufficiency. Although individual responses to operation were heterogeneous, renal revascularization may provide both immediate improvement in renal function and an improvement in its rate of deterioration during follow-up in patients with ischemic nephropathy.

Adult↗
PubMed1991

Intraoperative duplex sonography during renal artery reconstruction.

To assess renal duplex sonography as an intraoperative study to detect technical defects during repair, 57 renal artery reconstructions in 35 patients were studied. Sixteen men and 19 women (mean age, 62 years) underwent unilateral (13 patients) or bilateral (22 patients) renal artery repair to 57 kidneys. Methods of repair included aortorenal bypass grafting in 29 cases (20 saphenous vein, 5 polytetrafluoroethylene, 4 Dacron), reimplantation in 7, transrenal thromboendarterectomy with patch angioplasty in 13, and transaortic extraction thromboendarterectomy in 8. Branch renal artery repair was required in six cases (five in vivo, one ex vivo). Fourteen patients had combined aortic replacement (11 patients: 8 abdominal aortic aneurysms, 3 aortic occlusions) or visceral artery reconstruction (three patients: three superior mesenteric artery thromboendarterectomies, one inferior mesenteric artery thromboendarterectomy). Intraoperative renal duplex sonography (mean scan time, 4.5 minutes) was complete in 56 of 57 repairs (98%), and renal duplex sonography was normal in 44 repairs (77%). Overall, B-scan defects were present in 13 repairs (23%). Six of these (11%) were defined as major B-scan defects by Doppler spectra with focal increases in peak systolic velocity greater than or equal to 2.0 meters/sec (major defect, mean renal artery peak systolic velocity, 3.1 m/sec), which prompted immediate operative revision. Seven B-scan defects were defined as minor by Doppler spectra (minor defect, mean renal artery, peak systolic velocity, 0.7 m/sec) and were not revised. Postoperative evaluation (range, 1 to 22 months; mean follow-up, 12.4 months) of 55 renal artery repairs in 34 operative survivors (surface renal duplex sonography, 33 patients; renal angiography, 9 patients) demonstrated 42/43 renal artery repairs with normal intraoperative renal duplex sonography, and 6/6 repairs with minor B-scan defects were patent and free of critical stenosis. Of the 6 renal artery revisions prompted by major B-scan defects, 4 remained patent, 1 stenosed, and 1 occluded. Our experience suggests that intraoperative renal duplex sonography during renal artery repair provides valuable anatomic and physiologic information. Renal artery repairs with normal renal duplex sonography and minor B-scan defects without Doppler spectral changes demonstrated 98% patency without critical stenosis at 12.4 months of mean follow-up. However, major B-scan defects defined by a focal increase in renal artery peak systolic velocity should be considered for immediate correction.

Adult↗
PubMed1990

Renal duplex sonography: evaluation of clinical utility.

With the exception of conventional angiography, no previously proposed screening test has the necessary sensitivity/specificity to guide further evaluation for correctable renovascular disease. Recently, renal duplex sonography has been suggested as a useful substitute in such screening for renovascular disease. This report analyzes our data collected over the past 10 months in evaluation of renal duplex sonography to examine its diagnostic value. The study population for renal duplex sonography validity analysis consisted of 74 consecutive patients who had 77 comparative renal duplex sonography and standard angiographic studies of the arterial anatomy to 148 kidneys. Renal duplex sonography results from six kidneys (4%) were considered inadequate for interpretation. This study population contained 26 patients (35%) with severe renal insufficiency (mean 3.6 mg/dl) and 67 hypertension (91%). Fourteen patients (19%) had 20 kidneys with multiple renal arteries. Bilateral disease was present in 22 of the 44 patients with significant renovascular disease. Renal duplex sonography correctly identified the presence of renovascular disease in 41 of 44 patients with angiographically proven lesions, and renovascular disease was not identified in any patient free of disease. When single renal arteries were present (122 kidneys), renal duplex sonography provided 93% sensitivity, 98% specificity, 98% positive predictive value, 94% negative predictive value, and an overall accuracy of 96%. These results were adversely affected when kidneys with multiple (polar) renal arteries were examined. Although the end diastolic ratio was inversely correlated with serum creatinine (r = -0.3073, p = 0.009), low end diastolic ratio in 35 patients submitted to renovascular reconstruction did not preclude beneficial blood pressure or renal function response. We conclude from this analysis that renal duplex sonography can be a valuable screening test in the search for correctable renovascular disease causing global renal ischemia and secondary renal insufficiency (ischemic nephropathy). Renal duplex sonography does not, however, exclude polar vessel renovascular disease causing hypertension alone nor does it predict hypertension or renal function response after correction of renovascular disease.

Angiography↗
PubMed1989

Management of renovascular hypertension in the elderly population.

This article summarizes our experience with the operative management of renovascular hypertension in a contemporary population of elderly patients. During a recent 18-month period 35 of 74 patients (47%) undergoing an operation for renovascular hypertension at our center were in their seventh (21 patients) or eighth (14 patients) decade of life (mean age, 68 years). There were 17 men and 18 women with blood pressures ranging from 176/90 mm Hg to 280/215 mm Hg (mean, 213/121 mm Hg). Twenty-seven patients (77%) had renal insufficiency (serum creatinine greater than or equal to 1.3 mg/dl). Nineteen patients had severe insufficiency (serum creatinine greater than or equal to 2.0 mg/dl), with five of these patients being dependent on dialysis. Thirty-three of 35 patients (94%) had evidence of organ-specific atherosclerotic damage as manifested by cardiac disease (72%), cerebrovascular disease (37%), or renal insufficiency (77%). Operative management consisted of unilateral revascularization in 17 patients (includes three contralateral nephrectomies), bilateral renal revascularization in 17 patients, and primary nephrectomy in one. Simultaneous aortic replacement was performed in nine patients. There were two operative deaths (5.7%) and two postoperative graft thromboses (4%). Hypertension was cured (three) or improved (27) in 30 of the 33 survivors (91%). Renal function was improved in six and worsened in two patients with severe non-dialysis-dependent renal insufficiency. Three of five patients who were dependent on dialysis before surgery were removed from dialysis after renal revascularization. On follow-up (mean, 10.3 months) we found that five patients had died. This article emphasizes the complexity of atherosclerosis in the current population presenting for operative management of renovascular hypertension.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1987

Salvage of lower extremities following combined orthopedic and vascular trauma. A predictive salvage index.

A retrospective review of 676 tibial-fibular fractures and 985 femoral fractures treated over a 71-month period yielded associated major vascular trauma in 12 (1.7%) tibial-fibular fractures and in five (0.5%) femoral fractures. Vascular trauma combined with orthopedic trauma was also identified in four other cases--two disruptions of the pubic symphysis and two dislocations of the knee without fracture. Nine (43%) of the 21 involved limbs were eventually amputated. Limb survival was not related to the temporal relationship of vessel repair to skeletal stabilization; the presence or absence of shock on admission; the presence of associated but repaired venous injury; or the presence of unrelated injuries. Limb survival was related to the interval from injury to arrival in the operating room; the level of arterial injury; and the quantitative degree of muscle, bone, and skin injury. By combining these variables a limb salvage index was established that identified lower extremities likely to require amputation after combined orthopedic and vascular trauma (sensitivity 78%, specificity 100%). Use of this predictive salvage index may prevent the trauma surgeon from attempting to salvage a doomed or useless lower extremity and may thus permit early prosthetic rehabilitation to follow definitive primary amputation.

Adolescent↗
PubMed1986

Surgical revascularization of acute (1 hour) coronary occlusion: blood versus crystalloid cardioplegia.

This study compares blood versus crystalloid cardioplegia in restoring contractile function, and high-energy phosphate and tissue water content in a myocardial segment after 1 hour of coronary artery occlusion. Anesthetized dogs underwent instrumentation with the chest open to measure left ventricular and aortic pressures, and systolic shortening in the myocardium perfused by the left anterior descending coronary artery (LAD) was measured with ultrasonic crystals. In 21 dogs, the LAD was occluded for an hour, thereby replacing systolic shortening with passive lengthening averaging -28.7 +/- 6.2% of control shortening in both groups. The dogs were then placed on total bypass, and arrest was achieved with multidose crystalloid (N = 10) or blood cardioplegia (N = 11). The ligatures were released just prior to the second infusion of cardioplegic solution. Postischemic subendocardial levels of adenosine triphosphate were comparably depleted with crystalloid and blood cardioplegia (55.2% and 44.0%, respectively, of control). Subendocardial increases in water content were similar for crystalloid (3.62%) and blood (3.16%) cardioplegia. Recovery of segmental shortening was significantly greater with blood than crystalloid cardioplegia (31.5 +/- 8.2% versus 4.9 +/- 6.6% of control, respectively). We conclude that the composition and the delivery of blood cardioplegia used in this study restore greater postischemic function than crystalloid cardioplegia in acute evolving myocardial infarction.

Adenosine Triphosphate↗
PubMed1986

Ticlopidine versus aspirin and dipyridamole: influence on platelet deposition and three-month patency of polytetrafluoroethylene grafts.

In an attempt to establish a specific drug regimen that would retard neointimal fibrous thickening (NFT) and promote patency of small arterial grafts, we studied acute platelet accumulation and 3-month patency of 4 mm polytetrafluoroethylene (PTFE) grafts in dogs treated with oral aspirin (2 mg/kg/day) in combination with dipyridamole (5 mg/kg/day) (ASA/D) or ticlopidine (25 mg/kg/day) (T). After 3 days of treatment, 15 dogs were given indium 111-labeled autologous platelets and then had bilateral femoral artery grafts placed (control, 10 grafts; each drug group, 10 grafts). The calculated graft radioactivity expressed as average counts per 10 minutes +/- standard error of the mean (SEM) was as follows: control = 542,003 +/- 63,991; ASA/D = 135,163 +/- 14,443 (p less than 0.001, Student's t test); T = 104,650 +/- 14,004 (p less than 0.001). Bilateral femoral artery and carotid artery grafts were placed in 15 other dogs (control, 20 grafts; each drug group, 20 grafts). Three months later the 60 grafts were excised and their patency recorded: control = 20% (4 of 20 grafts); ASA/D = 70% (12 of 17 grafts) (p less than 0.01, chi-square analysis); T = 30% (6 of 20 grafts) (p greater than 0.05). Mean anastomotic NFT +/- SEM of each graft was measured with an ocular micrometer: control = 1.6 +/- 0.2 mm; ASA/D = 0.7 +/- 0.2 mm (p less than 0.001, Student's t test); T = 1.3 +/- 0.2 mm (p greater than 0.1).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1985

Metastatic oat cell carcinoma of the lung producing extrahepatic bile duct obstruction.

Although carcinoma of the lung metastatic to the pancreas is not unusual in autopsy series, it is rare as a cause of extra-hepatic bile duct obstruction among the living. We have reported two cases of oat cell carcinoma of the lung in which the first sign of metastatic disease was extrahepatic bile duct obstruction. Ultrasonography provides a quick, direct, and noninvasive means of evaluating such obstruction, allowing early diagnosis and surgical palliation.

Adult↗
PubMed1984

Expanded criteria for the diagnosis of deep venous thrombosis. Use of the pulse volume recorder and Doppler ultrasonography.

Over five years, we examined 1,698 patients for suspected deep venous thrombosis (DVT), using the pulse volume recorder (PVR) combined with Doppler ultrasonography. We report the 244 patients who subsequently underwent venography. Fifty-three (50%) of 106 patients with true-positive study results by venography had derived PVR-Doppler total venous scores (TVSs) of 4 or less, the accepted standard for a "normal" result. Had those TVSs alone been used to rule out DVT, all 53 patients would have had false-negative study results (sensitivity, 44%). Thus, total reliance on a TVS of 4 or less to exclude the diagnosis of DVT is inadequate. By using five "expanded criteria," we increased the test sensitivity to 90%. Thus, when a TVS of 4 or less is found, the presence of any of the expanded criteria mandates further examination to exclude DVT.

Adolescent↗
PubMed1984

Inhibition of platelet deposition on polytetrafluoroethylene grafts by antiplatelet agents.

The effects of ibuprofen (Motrin), dipyridamole (Persantine), and prostacyclin on the deposition of platelets on polytetrafluoroethylene grafts (5.5 cm long, 4 mm internal diameter implanted into both femoral arteries of 21 dogs) were studied by harvesting autologous platelets, labeling them with 51Cr, and reinjecting them 15 minutes before cross-clamping. Arterial flow was adjusted to 65 ml/min and monitored continuously. Ibuprofen (12.5 mg/kg) and dipyridamole (2.5 mg/kg) were each administered as a single intravenous injection in four dogs (eight grafts) and five dogs (10 grafts), respectively. Prostacyclin (50 ng/kg/min) was administered by continuous intravenous infusion in five dogs (10 grafts). Seven dogs (14 grafts) served as controls. Grafts were removed 2 hours after implantation, and radioactivity (counts per 10 minutes) was determined in four segments of each graft (including both anastomoses) with a gamma-counter. Counts were averaged for each group of dogs. Significance was calculated by the Student t test. Platelet deposition in control dogs averaged 10,033.9 +/- 1134.2 SE; that in prostacyclin-treated dogs averaged 2513.7 +/- 276 SE (p less than 0.001); that in ibuprofen-treated dogs averaged 5453.4 +/- 1336.3 SE (p = 0.02); that in dipyridamole-treated dogs averaged 11,213.7 +/- 1632.5 SE (p = 0.55). These data demonstrate the effectiveness of prostacyclin and ibuprofen in reducing platelet deposition on polytetrafluorethylene grafts in dogs.

Animals↗