Search PubMed⌕ Search

Biomedical subjects

D D Hansen

Publications and source records attributed to D D Hansen.

At least 37 records · Page 2Linked to original sources
PubMed1988

Rotational atherectomy in atherosclerotic rabbit iliac arteries.

PTCA is not technically possible in many patients with symptoms of coronary artery disease. In addition, atheroma is not physically removed by PTCA, and restenosis of the treated vessel is common. We have tested a new, rotating, abrasive-tipped angioplasty device in vivo in 13 atherosclerotic rabbit iliac vessels. Atherosclerosis was generated in rabbit iliac vessels by a 2% cholesterol diet combined with balloon endothelial injury for 10 weeks. The diseased vessels were then treated with the rotational atherectomy device. Before treatment, contrast angiograms demonstrated that initial percent diameter stenosis was 81% +/- 9%. After atherectomy, there was significant improvement, with residual 38% +/- 22% narrowing (p less than 0.001). One perforation resulted from distal guidewire manipulation, and one vessel was occluded by the device. Histologic examination demonstrated loss of portions of the diseased intima in all cases. Particles were produced for analysis in vitro by operating the atherectomy device in atherosclerotic rabbit aortas perfused with saline solution. Ninety-eight percent of the particles produced by the device were less than 10 micron in diameter. We conclude that this new rotational device can remove atheromatous material from diseased arteries in rabbits. Such a device may complement other angioplasty techniques and lead to wider application of catheter-based therapeutic interventions.

Animals↗
PubMed1988

Rotational endarterectomy in normal canine coronary arteries: preliminary report.

Endarterectomy was performed in vivo using a high speed rotating abrasive-tipped catheter device in 11 normal canine coronary arteries. The device is designed to remove atheromatous material from diseased arteries by the abrasive action of its rotating tip. It was operated percutaneously from a femoral approach using conventional angioplasty guiding equipment. The rotating device was advanced over a guide wire from just beyond the tip of the guide catheter into the distal vessel. Six arteries were harvested immediately after endarterectomy and five were left in place for 7 +/- 2.8 days; in the latter group, the animals were maintained on a regimen of aspirin, 325 mg/day. Angiography before and after treatment demonstrated vessel patency in all cases. Caliper-measured luminal diameters were not significantly changed after endarterectomy. Histologic examination of pressure-fixed vessels showed extensive intimal loss and 20 to 30% loss of the internal elastic lamina. Medial damage was superficial and never exceeded 40% of the total medial thickness. There were no vessel perforations. Results of histologic study of the myocardium supplied by the treated vessels were normal without evidence of distal embolization or infarction. It is concluded that a high speed rotating abrasive device can be safely operated percutaneously in normal coronary arteries and results in minimal vessel damage and continued patency at 7 +/- 2.8 days.

Angioplasty, Balloon↗
PubMed1987

Mechanical thrombectomy: a comparison of two rotational devices and balloon angioplasty in subacute canine femoral thrombosis.

In this study, two prototype rotational devices were compared to balloon angioplasty in a canine model of subacute arterial thrombosis. Radiographic 2- to 8-day-old total thrombotic occlusions were produced in 30 canine femoral arteries. A high-speed rotating device with a cutting tip was used in 18 arteries. Successful opening occurred in every case, with a residual percent diameter stenosis at 45 +/- 25%. Vessel perforation was seen in 6 of the 18 arteries. A noncutting rotational thrombectomy catheter was used in six arteries. Radiographic patency was established in two of six (residual stenosis 86 +/- 28%), with one perforation with the use of the noncutting thrombectomy catheter. Balloon angioplasty reestablished radiographic patency in three of six arteries (residual stenosis 77 +/- 2%). No perforations were seen with balloon dilation, but radiographic distal emboli were always observed. No radiographic emboli were observed with either of the rotational devices. We conclude that subacute arterial thromboses are easily opened with an abrasive-tipped rotating angioplasty device. Although perforations are relatively common with this prototype equipment, design changes may produce a clinically useful angioplasty device.

Angioplasty, Balloon↗
PubMed1987

Rotational approaches to atherectomy and thrombectomy.

We have developed and tested a rotational, mechanical approach to arterial plaque removal (PTRA or Percutaneous Transluminal Rotational Atherectomy). An elliptical burr is rotated by a helical driveshaft at 150,000 rpm. The tip of the burr is embedded with small diamond chips, 30 micron in diameter. Plaque is thus abraded and particles of 2-5 micron in diameter are released downstream. Preliminary studies in a rabbit model of iliac atherosclerosis showed a reduction in percent diameter stenosis from more than 80% to less than 40%. Perforations are the current principal complication, occurring in 2 of the 13 rabbit arteries. A second rotational catheter system has been developed for removal of fresh thrombus (PRT-Percutaneous Rotational Thrombectomy). Low speed rotation (5000 rpm) of a non-cutting catheter promotes the selective winding of fibrin with subsequent lysis of thrombus. This was effective in 20 out of 21 total thrombotic occlusions in a canine model of fresh clot, with a single perforation early in the experiment.

Animals↗
PubMed1986

Pulmonary and systemic hemodynamic effects of nitrous oxide in infants with normal and elevated pulmonary vascular resistance.

The hemodynamic response to 50% nitrous oxide was studied in 12 sedated but responsive infants in the intensive care unit following repair of their congenital heart disease. One-half of the infants studied had an elevated pulmonary vascular resistance index (PVRI greater than 3.5 Wood units). During mechanical ventilation with a fractional inspired O2 concentration (FIO2) of 0.5, hemodynamic parameters were measured after equilibration with 50% nitrogen and then after 50% nitrous oxide. The sequence was repeated once to assure reproducibility of the responses. Average heart rate decreased by 9%, mean arterial blood pressure decreased by 12%, and cardiac index decreased by 13% in both the elevated and normal PVRI groups each time nitrous oxide was given. Although statistically significant, these changes would not generally be clinically important except in infants with severely compromised cardiovascular reserve. In contrast, pulmonary artery pressure and PVRI were not significantly changed by administration of 50% nitrous oxide in either the group with normal PVRI or the group with preexisting elevated PVRI. We conclude that while these mild depressant effects of nitrous oxide on systemic hemodynamics in infants are similar to those previously reported in adults, in infants nitrous oxide does not produce the elevations in pulmonary artery pressure and pulmonary vascular resistance seen in adults.

Age Factors↗
PubMed1986

Mechanical thrombolysis: a new rotational catheter approach for acute thrombi.

We tested a new rotational thrombectomy catheter in acute thrombi formed both in vitro and in vivo. The catheter consisted of a rounded platinum tip, 0.025 inch diameter by 0.08 inch long, attached to a flexible steel guidewire supported by an external sheath. In vitro, the force required to penetrate thrombus was reduced fivefold by rotation of the catheter at 4000 rpm (0.75 +/- 1.2 g rotating vs 3.9 +/- 2.1 g static; p less than .001). Fibrin was extracted selectively from the thrombus and tightly wound about the shaft (3.8 +/- 1.5 mg rotating vs 0.75 +/- 0.4 mg static; p less than .001). In vivo, subtotal or complete thrombosis of the canine femoral artery was created. Thrombectomy by catheter rotation always produced tightly wound adherent fibrin on the catheter shaft. Angiographic patency was restored in 20 of 22 (91%) arteries, totally in seven of 22 (32%) and partially (greater than 20% increase in lumen diameter) in 13 of 22 (59%). There was one arterial perforation (5%). We conclude that this new mechanical catheter device reduces the force required to penetrate thrombus. Additionally, by winding fibrin about its shaft, the catheter is able to selectively remove the fibrin matrix of thrombus. Thus both the ease of initial thrombus recanalization as well as physical removal of thrombus are promoted by this new approach. Such an approach may be relevant to the treatment of recent thrombosis in acute myocardial infarction.

Acute Disease↗
PubMed1986

Anesthesia for hypoplastic left heart syndrome: use of high-dose fentanyl in 30 neonates.

The anesthetic management of the first stage palliative surgical repair of hypoplastic left heart syndrome with a high-dose fentanyl (50 micrograms/kg)-pancuronium (0.14 mg/kg) anesthetic technique is described in 30 neonates. Previously this severe form of congenital heart disease carried a 100% rate of mortality. The pathophysiology that leads to this mortality is explained and related to the surgical procedure utilized for palliation. The major problem encountered intraoperatively was control of pulmonary blood flow. Management of the effect of anesthesia and intraoperative events on pulmonary blood flow was important because the rapid flux in pulmonary vascular resistance during the postnatal and perioperative period is the major destabilizing factor in these neonates. Ventricular fibrillation with surgical manipulation was a minor problem in the present series but was a major problem in an earlier series where a low dose narcotic-nitrous oxide technique was used. Ventricular fibrillation probably occurred due to the relative coronary insufficiency resulting from the anatomy present in this syndrome.

Anesthesia↗
PubMed1985

Pulmonary and systemic hemodynamic responses to ketamine in infants with normal and elevated pulmonary vascular resistance.

Avoidance of ketamine has been recommended in children with pulmonary hypertension or with limited right ventricular reserve, despite absence of data about the effects of ketamine on pulmonary vascular resistance (PVR) in children. Ketamine has been associated with increased PVR in studies of adults; in these studies adults were spontaneously breathing through unprotected airways, despite ketamine's known effects of ventilatory depression and partial loss of airway. The authors measured pulmonary and systemic hemodynamic responses to ketamine during spontaneous ventilation in 14 intubated infants who were receiving minimal ventilatory support with an intermittent mandatory ventilation (IMV) of 4 at an FIO2 of 0.3-0.4. No significant changes were found in cardiac index (CI), pulmonary vascular resistance index (PVRI), or systemic vascular resistance index (SVRI) in a group of seven infants with normal PVRI or in another group of seven infants with preexisting increased PVRI. Results did not differ in infants receiving diazepam sedation. The authors conclude that ketamine has little effect on baseline hemodynamics in mildly sedated infants whose airway and ventilation are maintained; in particular, PVRI is little changed by ketamine administration in ventilated infants with either normal or increased baseline PVRI.

Blood Gas Analysis↗
PubMed1985

Pulmonary and systemic hemodynamic responses to fentanyl in infants.

Pulmonary and systemic hemodynamic responses to fentanyl were studied in 12 infants after repair of congenital heart defects. During controlled ventilation, hemodynamic responses to 25 micrograms/kg of fentanyl were measured. No significant changes were found in heart rate, cardiac index, mean pulmonary artery pressure, or pulmonary vascular resistance index 5 min after the fentanyl had been given. There were small but statistically significant decreases in mean arterial pressure and systemic vascular resistance index after fentanyl. We conclude that under the conditions of this study, pulmonary and systemic hemodynamics in infants are minimally altered by 25 micrograms/kg of fentanyl.

Blood Pressure↗
PubMed1985

Blunting of stress responses in the pulmonary circulation of infants by fentanyl.

After repair of congenital heart defects, stress responses in the pulmonary circulation of fourteen infants produced by a brief endotracheal suctioning procedure were studied before and after fentanyl (25 micrograms/kg). The total time of disconnection from the ventilator with suctioning (FIO2 1.0) was limited to no more than 15 sec to avoid alveolar hypoxia. Before fentanyl, marked increases occurred in mean pulmonary artery pressure and pulmonary vascular resistance index with suctioning, whereas only mild increases in heart rate and mean systemic arterial pressure occurred. All of these increases with suctioning were almost completely abolished by 25 micrograms/kg fentanyl. We conclude that suctioning or other broncho-carinal stimulation can produce a marked pulmonary vasoconstrictive response in infants, which is blunted by fentanyl. This response is separate from that produced by hypoxic pulmonary vasoconstriction associated with prolonged clinical suctioning procedures or with loss of airway.

Blood Pressure↗
PubMed1984

Fentanyl- and sufentanil-oxygen-pancuronium anesthesia for cardiac surgery in infants.

The safety and efficacy of fentanyl-oxygen (50 and 75 micrograms/kg) and sufentanil-oxygen (5 and 10 micrograms/kg) were studied in 40 infants undergoing repair of complex heart defects. When fentanyl or sufentanil was given simultaneously with pancuronium, induction of anesthesia was rapid and smooth with only mild and clinically insignificant hemodynamic changes. Hemodynamic responses to tracheal intubation were completely blocked, whereas hemodynamic responses to surgical incision and sternotomy were partially and variably blocked. Except for somewhat more effective blocking of responses to surgical stimulation by sufentanil, the effects of both narcotics were similar. No significant differences in effects were found between the two dose levels of either drug. Transcutaneous oxygen tensions increased with induction, intubation, and surgical stimulation with both fentanyl and sufentanil, even in cyanotic patients with right to left shunts. Fentanyl- and sufentanil-oxygen-pancuronium anesthesia were both safe and effective for cardiac surgery in infants. This study raises the question of possible beneficial effects of high dose fentanyl and sufentanil in blunting stress responses in the pulmonary circulation, a critical aspect of anesthesia and intensive care in the infant and neonate.

Anesthesia↗
PubMed1984

Anesthetic complications in surgery for congenital heart disease.

Anesthetic complications in 500 consecutive operations for congenital heart disease were studied and their contribution to mortality and morbidity were assessed. The great majority of the cases were young and sick children in ASA Class III, IV, or V with complex congenital heart disease. Anesthetic mortality was zero and hospital mortality was 6.3%. Anesthetic complications occurred in 2% of the cases. Four major complications were seen, including two tension pneumothoraces, one episode of severe hypotension on induction, and a breathing circuit malfunction on induction leading to bradycardia and hypotension. Six minor complications included two cases of premature extubation that required reintubation postoperatively, one case of subglottic edema, airway obstruction from inadvertent tracheal insertion of an esophageal temperature probe, one corneal abrasion, and one case of erosion of the nasal ala secondary to a nasotracheal tube. Half of the complications were probably preventable, but the other half of the complications occurred despite specific attempts at their prevention.

Adjuvants, Anesthesia↗
PubMed1981

Subcutaneous fat necrosis of the newborn. A case report.

A 3-day-old infant, born to a mother with preeclampsia, suffered intrauterine asphyxia and subsequently had multiple erythematous subcutaneous plaques and nodules. The clinical setting, the skin manifestations, and the histologic appearance of the lesions were diagnostic of subcutaneous fat necrosis of the newborn. Transient thrombocytopenia was noted with the appearance of the skin lesions, but returned to normal as the skin lesions spontaneously resolved.

Fat Necrosis↗
PubMed1980

The anaesthetic management of preterm infants undergoing ligation of patent ductus arteriosus.

The authors reviewed the records of seventy preterm infants suffering from respiratory distress syndrome and, in most cases, refractory congestive heart failure, who underwent ligation of patent ductus arteriosus. The peri-operative management of these patients is described. The anaesthetic technique consisted of nitrous oxide and oxygen supplemented with a relaxant. All patients were ventilated manually with a humidified Jackson Rees system. The operations were performed in the main operating suite. There were no deaths during operation. The infants were protected from significant temperature fluctuations by various methods which are described. The overall survival rate of all preterm infants with respiratory distress syndrome. The management presented is considered acceptable to the infants, to the surgeons and to the anaesthetists.

Anesthesia, General↗
PubMed1979

Tricho-rhino-phalangeal syndrome.

The major characteristics of tricho-rhino-phalangeal syndrome (TRPS) include shortened and deviated digits, a typical facies with a pear-shaped nose, a long philtrum and slow-growing, fine, sparse hair. Cone-shaped digital epiphyses are seen on x-ray. A few patients with TRPS are mentally retarded. Associated endocrine abnormalities have been reported. Autosomal dominant and recessive patterns of inheritance have been described with most cases showing a dominant mode of inheritance.

Adult↗