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Biomedical subjects

R S Hartz

Publications and source records attributed to R S Hartz.

At least 55 records · Page 3Linked to original sources
PubMed1987

Arterial aneurysm model using laser energy.

Continuous wavelength laser energy can be used to perform arterial anastomoses, but all experimental series report an incidence of anastomotic aneurysm formation. To elucidate the mechanism of aneurysm production, controlled injuries of the arterial wall were created with a pulsed CO2 laser beam (40-50 mW). One carotid and one femoral artery of 10 New Zealand rabbits were injured with laser and the contralateral vessel was exposed surgically as a sham operation. At reoperation 8 to 11 weeks later, all 40 arteries were patent. None of the carotid shams, one carotid laser, two femoral shams, and eight femoral laser vessels (80%) were aneurysmal. Histologic examination revealed extensive medial necrosis with fragmentation of the internal elastic lamina in the area of these aneurysms. Femoral vessels were significantly smaller than carotids (P less than 0.001) and the high incidence of aneurysm formation in the former may be due to the relatively greater area of injury. This new model of aneurysm formation after laser injury suggests a need for further study prior to clinical application of this technology, especially in vessels smaller than 2 mm in diameter.

Aneurysm↗
PubMed1987

Wound healing in porcine skin following low-output carbon dioxide laser irradiation of the incision.

Wound healing of scalpel incisions to the depth of adipose tissue closed with conventional methods was compared with closure by low-output carbon dioxide laser irradiation. In 3 Pitman-Moore minipigs wound healing was evaluated at intervals from 1 to 90 days by the following methods: clinical variables of wound healing; formation of the basement membrane components bullous pemphigoid antigen, laminin, and fibronectin; and histological evaluation of the regeneration of the epidermis, neovascularization, and elastin and collagen formation. There was no significant difference in healing between wounds closed by the various conventional methods and by the low-output carbon dioxide laser.

Animals↗
PubMed1987

Patency of laser-assisted anastomoses in small vessels: one-year follow-up.

Laser-assisted arterial anastomoses can now be performed with satisfactory short-term patency. This study was undertaken to evaluate patency and aneurysm formation with a 1-year follow-up. A microscopically guided CO2 laser was used to anastomose 1.5 to 2.0 mm carotid arteries in 24 rabbits. Under X6 to X40 magnification, 60 to 70 mW were delivered with a spot size of approximately 0.32 mm. One carotid artery underwent laser anastomosis; the opposite served as a sutured control (10-0 nylon sutures). The 48 end-to-end anastomoses were evaluated for patency and aneurysm formation at 3, 6, and 12 months. Aneurysms were defined as a 1.5 times increase in diameter at the anastomotic site. The vessels underwent microscopic examination. All laser-assisted and sutured anastomoses were patent up to 1 year. At 3 months, one of eight sutured and one of eight laser anastomoses were aneurysmal; stenosis was noted in one laser anastomosis. At 6 months, one of eight laser and 0 of eight sutured anastomoses were aneurysmal. At 12 months, one of eight rabbits had died; of the remaining seven, three of seven laser and zero of seven sutured anastomoses were aneurysmal. In total, five of 23 (21.7%) aneurysms developed with the laser technique and one of 23 (4.3%) with the suture technique (p less than 0.05). Laser-assisted anastomoses are technically feasible, and patency at 1 year is equal to those performed with the suture technique. Aneurysm formation is a consistent problem that demands further investigation.

Aneurysm↗
PubMed1986

The low-output carbon dioxide laser for cutaneous wound closure of scalpel incisions: comparative tensile strength studies of the laser to the suture and staple for wound closure.

The low-output carbon dioxide (CO2) laser was used for cutaneous wound closure of scalpel incisions. Cutaneous scalpel incisions were placed over the dorsum of three minipigs and were then closed by either the laser, sutures, or staples. At multiple time points after wound closure, up to day 90, the tensile strengths of these wounds were comparatively evaluated. All wounds, including those closed with the laser, clinically appeared to heal similarly with no evidence of wound dehiscence or infection. Tensile strength studies revealed similar sigmoid curves for all wound closure modalities with low initial tensile strengths up to days 14 to 21, which afterwards increased rapidly, with a plateau toward day 90. From our study, it appears that the CO2 laser, in the low-output mode, can be used for cutaneous wound closure and that similar clinical healing and tensile strength measurements are obtained relative to the conventional cutaneous wound closure modalities of the suture or staple.

Animals↗
PubMed1986

Vascular anastomoses with laser energy.

Laser-assisted arterial and venous anastomoses are now feasible. A microscope-guided CO2 laser was used to deliver 60 to 100 mW to anastomose end to end 44 rabbit carotid arteries (1.5 to 2.0 mm) and 27 rabbit vena cavae (4 to 6 mm). These were compared with control arteries repaired with interrupted suture technique. Anastomoses were examined from between 24 hours and 19 weeks. Laser carotid anastomoses yielded 93% patency (41 of 44) and 9% aneurysms (4 of 44), whereas hand-sewn carotid anastomoses produced 91% patency (40 of 44) and no aneurysms. In the vena cava, 26 of 27 laser anastomoses were patent (96%) compared with 19 of 20 (95%) sutured controls. Venous aneurysmal dilatation was seen in 2 of 27 laser (7%) and in 3 of 20 (15%) hand-sewn anastomoses. Histologic examination of laser-assisted anastomoses showed local full-thickness thermal injury. Repair was by fibroblast and myofibroblast proliferation, and luminal cell coverage was complete by 14 days in both laser and sutured repairs. Laser arterial and venous anastomoses are attractive because of their simplicity and rapidity of performance. Their patency is comparable to sutured anastomoses, but arterial aneurysms remain a hazard despite use of extremely low laser energy.

Animals↗
PubMed1986

Ruptured thoracic aneurysm: unusual manifestation and early diagnosis using CT.

Rupture of a thoracic aortic aneurysm across the posterior mediastinum into the right side of the chest is rare. The diagnosis may be delayed by the absence of expected findings in the left side of the chest. We recently encountered two patients with thoracic aneurysm rupture who came to medical attention initially because of right-sided pleural and/or extrapleural hematomas, which were accurately diagnosed preoperatively on the basis of computed tomography (CT) findings. Aortography, performed in one patient, added no useful information. Because CT accurately identifies the presence of pleural or extrapleural blood, as well as the underlying aneurysm or dissection, CT should be the first examination performed in cases of suspected thoracic aneurysm rupture.

Aged↗
PubMed1986

An eight-year experience with porcine bioprosthetic cardiac valves.

A total of 589 porcine bioprostheses were implanted in 509 patients from January, 1976, through December, 1983. Of the valves implanted, 390 were Hancock and 199 were Carpentier-Edwards. A total of 1,633 patient-years was accrued, with a mean follow-up of 38 months per patient. Two hundred eight patients had aortic valve replacement, 209 had mitral valve replacement, and 79 had multiple valve replacements, of which 46 were aortic and mitral replacements. The mortality for isolated aortic valve replacement was 5.8%; for isolated mitral replacement, 8.6%, and for all patients, 10.9%. Late mortality was 3.9% per patient-year. The actuarial survival rate at 5 years was 79% for aortic, 68% for mitral, and 76% for aortic-mitral valve replacement. There were 12 thromboembolic events (0.73% per patient-year). Two episodes occurred in patients with an aortic bioprosthesis, nine in patients with a porcine mitral valve, and one in a patient with mitral and tricuspid bioprosthetic valves. The probability of remaining free of thromboembolism at 5 years was 99% for the group having aortic valve replacement, 93% for those having mitral replacement, and 100% for the group having aortic-mitral valve replacements. Thirteen episodes of endocarditis occurred (0.8% per patient-year). Seven of the 13 patients died as a direct result of endocarditis. The probability of remaining free of prosthetic endocarditis at 5 years was 97% for the aortic valve replacement group, 95% for the mitral group, and 97% for the aortic-mitral group. There were 20 instances of xenograft failure (1.2% per patient-year). The probability of remaining free of valve failure at 5 years was 96% for the aortic valve replacement group, 93% for the mitral group, and 93% for the aortic-mitral replacement group. Primary tissue failure of a prosthesis occurred in seven patients, all with Hancock valves (0.43% per patient-year). As yet there has been no primary tissue failure of the Carpentier-Edwards prosthesis. There also appears to be a lower incidence of thromboembolism (Edwards, 0.3% per patient-year; Hancock, 0.8% per patient-year) and endocarditis (Edwards, 0.6% per patient-year; Hancock, 1.0% per patient-year). The low incidence of complications with the porcine bioprosthetic valve, especially the Carpentier-Edwards, encourages us to recommend its continued use, especially in situations in which anticoagulation is contraindicated.

Adult↗
PubMed1986

Comparative study of warfarin versus antiplatelet therapy in patients with a St. Jude Medical valve in the aortic position.

To determine the necessity of long-term warfarin anticoagulation after St. Jude Medical aortic valve replacement in adults, we evaluated the risks of thromboembolism, valve thrombosis, anticoagulant hemorrhage, and sudden cardiac death in two groups of patients. Group I consisted of 41 patients treated with conventional long-term warfarin therapy. Forty-two patients in Group II were treated primarily with antiplatelet therapy (aspirin, dipyridamole, or both); 17 of these patients received warfarin for a short time postoperatively and seven others received it intermittently during the study period. The groups were similar with respect to age, sex, associated cardiovascular disease, and length of follow-up (mean 29 months per patient). In the warfarin-treated group, three late sudden deaths occurred, one of which was preceded by a cerebrovascular accident, for a cardiac mortality of 2.7% per patient-year. There were eight major nonfatal complications (7.3% per patient-year), of which four were hemorrhagic and four embolic. In Group II, there was one sudden cardiac death (1.1% per patient-year) and four major complications occurred (3.2% per patient-year). Two of the complications were embolic and two were episodes of valve thrombosis, both necessitating reoperation. Although the incidence of serious morbidity in the warfarin-treated group was twice that of patients treated with antiplatelet therapy, there were no statistically significant differences in the rates of sudden death or major complications. These data suggest that antiplatelet therapy may be as effective as warfarin in preventing embolism from the St. Jude Medical valve in the aortic position. Valve thrombosis occurred in two patients, both receiving antiplatelet therapy (2.2% per patient-year). Whether this type of valve failure can be prevented by warfarin remains in question.

Adolescent↗
PubMed1985

Interhospital transport of patients with ongoing intraaortic balloon pumping.

During a 5-year period (1979 to 1983), 50 consecutive patients undergoing continuous intraaortic balloon (IAB) pumping were transferred from Evanston Hospital to Northwestern Memorial Hospital (16 miles), where they underwent cardiac operation. All patients had cardiac catheterization before transfer. Indications for IAB were cardiogenic shock (9 patients), postinfarction angina (18 patients), unstable angina (9 patients), evolving myocardial infarction (3 patients), accelerating angina or hemodynamic instability during cardiac catheterization (9 patients) and prophylactic insertion for high-grade left main stenosis (2 patients). Transportation after stabilization was uneventful in all patients. All patients underwent operative coronary revascularization. There was concomitant mitral valve replacement in 3 patients, acute ventricular septal defect repair in 1 patient, aortic valve replacement in 1, and ventricular aneurysmectomy in 1. Three patients (5%) died postoperatively. Nine patients (20%) had complications directly related to IAB insertion. One patient required femoral-femoral arterial bypass preoperatively, 4 patients had postoperative lower limb ischemia treated by IAB removal or thrombectomy and 1 patient had thrombocytopenia (less than 60,000/mm3), 1 false aneurysm, 1 anterior compartment syndrome and 1 prolonged bleeding at the insertion site. Interhospital transfer with IAB pumping in progress should not be restricted to patients with cardiogenic shock, but can be effectively used for all patients who require preoperative IAB insertion.(ABSTRACT TRUNCATED AT 250 WORDS)

Assisted Circulation↗
PubMed1985

Evaluation of the carbon dioxide laser for performance of gastrointestinal myotomies.

Using a conventional carbon dioxide laser set at 8-W continuous-wave energy, a technique was developed in the animal laboratory to incise only the muscularis of the pylorus leaving the mucosa and submucosa intact. Similar esophageal myotomies were performed with less success, due to the rich submucosal venous plexus causing obscuring hemorrhage and to the reapproximation of the longitudinal esophageal muscle over a 3-week period. The technique for esophageal myotomy requires further refinement, but pyloromyotomy appears applicable for controlled human trials.

Animals↗
PubMed1985

New applications of the laser in pulmonary surgery: hemostasis and sealing of air leaks.

In thoracic surgery, the laser has been used primarily as a destructive instrument (e.g., for extirpation of endobronchial lesions and for skin incisions). Previously, the carbon dioxide laser was used for its scalpel-like action but not for sealing. The neodymium:yttrium aluminum garnet (Nd:YAG) laser not only cuts but also seals blood vessels and bronchi. We have modified the CO2 laser technique to seal vessels and bronchi up to 3 mm on a cut surface by using low power in a defocused mode, and have evaluated the method in 12 dogs. Matched lesions in the lingula were sealed with each type of laser and compared with lesions closed by suture technique. These lesions were then evaluated at biweekly intervals up to 6 weeks following operation. All lesions demonstrated substantial air leak and bleeding prior to sealing. There was no bleeding or air leak (40 cm H2O of pressure) at any time after sealing (laser or suture). The CO2 laser sealing consistently produced the least damage both macroscopically and microscopically. However, this technique requires a relatively bloodless field. The Nd:YAG laser produced the deepest tissue destruction but functioned well under conditions of poor hemostasis. Suture closure produced large early injuries, which subsided gradually to approach the amount of damage seen with the CO2 laser. These studies demonstrate that the laser may be a useful adjunct to maximally preserve normal lung tissue and to seal bleeding, leaking, raw lung surfaces. Results of early clinical trials are also detailed.

Aged↗
PubMed1985

Experimental air leaks in lung sealed by low-energy carbon dioxide laser irradiation.

When a focused carbon dioxide laser beam strikes a surface of tissue, the light energy is converted instantly into thermal energy, causing cells directly in the laser's path to vaporize. Because the carbon dioxide laser's energy is well absorbed by water, this thermal effect is attenuated at a distance of 100 mu. If the laser beam is "defocused," the same thermal energy is dissipated over a larger area, causing only desiccation and melting of tissue without vaporization; however, the depth of injury remains shallow. This modified technique has been used to seal artificially created air leaks in the canine lung. Twelve mongrel dogs were anesthetized, intubated, and ventilated. The lingula was exposed sterilely through a left thoracotomy. A 1 X 3-mm hole was made in the lung at 1 cm from the edge. The created air and blood leaks were sealed with a defocused carbon dioxide laser beam set at 8 W (32 W/sq cm). Each tissue "weld" withstood 40 cm H2O of peak ventilation pressure without leak. At the time of reoperation three weeks later, there was apparent complete healing of the pulmonary surface. No air leaks were present. Histologic examination showed a small zone of amorphous coagulated pleura and lung overlying a zone of minimal atelectasis. Normal lung was present within 150 mu of the laser seal. This new technique was performed safely and easily with currently available carbon dioxide lasers in the laboratory. It is presently undergoing intraoperative trials in a controlled clinical setting.

Animals↗
PubMed1985

Inhibition of electrogenic Na-pumping attributable to binding of cardiac steroids to high-affinity pump sites in human atrium.

Binding of cardiac steroids to the Na,K-pump may occur at both high- and low-affinity sites. Binding at low-affinity sites causes pump inhibition. However, the functional significance of binding at high-affinity sites is controversial. The effects of cardiac steroids presumed bound at high-affinity sites on electrogenic Na-pumping was therefore examined in human atrial tissue. Specimens were preloaded with Na+ by cooling to 2 degrees C for 60 min and then rewarmed to 30 degrees C in 20 mM K+. In nine control experiments, the resting membrane potential hyperpolarized to -69.9 +/- 0.7 mV (mean +/- S.E.) due to enhanced Na,K-pump activity upon rewarming. Maximal hyperpolarization was less negative during exposure to 10(-9) to 10(-6) M acetylstrophanthidin in a dose-dependent manner. The differences between maximal hyperpolarization during control experiments and during exposure to acetylstrophanthidin were attributed to pump inhibition. Inhibition occurred at all acetylstrophanthidin concentrations including the low range in which binding at high-affinity sites should predominate. The relationship between acetylstrophanthidin concentration and pump inhibition was bimodal with a "shoulder" around 10(-8) M. The data were well described by a model which assumes that acetylstrophanthidin binds at both low capacity-high-affinity (half-saturation, 3.9 X 10(-9)M) and high capacity-low-affinity sites (half-saturation, 4.8-6.1 X 10(-7) M). Nonlinearity in the experimental assay of pump function did not appear to explain the bimodal concentration-inhibition relationship. Thus, cardiac steroids may cause Na,K-pump inhibition in humans by binding to high-affinity pump sites.

Acetylcholine↗
PubMed1984

Pleural ascites without abdominal fluid: surgical considerations.

The presence of ascitic fluid in the pleural cavity in the absence of peritoneal fluid is rare. We have recently encountered two patients who presented with red-sided pleural effusions and no abdominal ascites. Both patients had diaphragmatic defects: One was an old traumatic diaphragmatic tear and the other a pinpoint spontaneous perforation. These cases are unique because the diagnosis of total ascitic fluid movement across the diaphragm was made during life, and the condition was surgically corrected. The literature concerning transdiaphragmatic movement of fluid is reviewed, and an operative approach is outlined.

Adult↗
PubMed1980

Healing of the perineal wound.

The operative management of the perineal wound of 100 consecutive patients undergoing abdominoperineal resection or total proctocolectomy was readily divided into four categories: (1) left open with simple packing, (2) closed primarily with simple drainage (Penrose or red rubber), (3) closed primarily with suction drainage (airtight and watertight), or (4) closed primarily with suction drainage plus continuous irrigation. At three weeks, none of the open wounds, 11% of those closed with simple drainage, 48% closed with suction, and 60% of those closed with suction plus irrigation were healed. By three months, the cumulative figures were 20%, 44%, 88%, and 87%, respectively, and at one year, 92%, 77%, 95%, and 97%. No difference was found between the wounds closed with suction and those closed with suction plus irrigation. There was a highly significant difference in the rate of wound healing when the wounds closed with suction alone or with irrigation were compared with those left open or closed with simple drainage. At three months, the former wounds were healed in 88% of the patients, and the latter in only 30%. The method of choice of management of the perineal wound appears to be that of primary closure with immediate suction drainage with or without concomitant irrigation.

Adenocarcinoma↗
PubMedDate not supplied

Aggressive blood conservation in coronary artery surgery: impact on patient care.

Data on 100 consecutive non-emergency coronary artery bypass (CABG) patients were analyzed retrospectively. Sixty-nine patients received no homologous blood (Group I). Thirty-one patients received a total of 118 units of blood products averaging 2.23 units of red cells (Group II). The average red cell transfusion rate for all patients was 0.7 units per patient. The median age for Group I was 61 and Group II was 68 years (p less than 0.05). The average number of grafts was the same for both (3 per patient) with 75% of Group I and 58% of Group II receiving internal mammary artery (IMA) grafts (p less than 0.05). Twelve of the Group II patients who received intraoperative transfusions on cardiopulmonary bypass to maintain adequate hemoglobin levels were older and had lower admission hematocrits: 36 +/- 0.8% compared to 41 +/- 0.5% for all other patients (p less than 0.05). Average postoperative blood loss was 889 +/- 38 ml for Group I and 1077 +/- 104 ml for Group II (p less than 0.05). Increased hemorrhage was correlated with bypass time and IMA use but not with preoperative heparin administration, pre-existing risk factors (diabetes, hypertension, etc.), bleeding time, post-bypass clotting time, age or number of grafts. Two patients in Group II and none in Group I required exploration for excessive postoperative hemorrhage. Mortality rate was 2% (both in Group II, neither transfusion related). Discharge hematocrits were the same for all at 29.4 +/- 0.4%. Among anemia-related postoperative symptoms, only sinus tachycardia was significantly higher in Group I (20%) compared to Group II (6.5%).(ABSTRACT TRUNCATED AT 250 WORDS)

Age Factors↗