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Biomedical subjects

F Robicsek

Publications and source records attributed to F Robicsek.

At least 73 records · Page 4Linked to original sources
PubMed1996

Aprotinin for primary coronary artery bypass grafting: a multicenter trial of three dose regimens.

BACKGROUND: High-dose aprotinin reduces transfusion requirements in patients undergoing coronary artery bypass grafting, but the safety and effectiveness of smaller doses is unclear. Furthermore, patient selection criteria for optimal use of the drug are not well defined. METHODS: Seven hundred and four first-time coronary artery bypass grafting patients were randomized to receive one of three doses of aprotinin (high, low, and pump-prime-only) or placebo. The patients were stratified as to risk of excessive bleeding. RESULTS: All three aprotinin doses were highly effective in reducing bleeding and transfusion requirements. Consistent efficacy was not, however, demonstrated in the subgroup of patients at low risk for bleeding. There were no differences in mortality or the incidences of renal failure, strokes, or definite myocardial infarctions between the groups, although the pump-prime-only dose was associated with a small increase in definite, probable, or possible myocardial infarctions (p = 0.045). CONCLUSIONS: Low-dose and pump-prime-only aprotinin regimens provide reductions in bleeding and transfusion requirements that are similar to those of high-dose regimens. Although safe, aprotinin is not routinely indicated for the first-time coronary artery bypass grafting patient who is at low risk for postoperative bleeding. The pump-prime-only dose is not currently recommended because of a possible association with more frequent myocardial infarctions.

Aged↗
PubMed1996

Surgical repair of extensive myocardial infarction: ventricular aneurysmectomy according to Dor with exclusion-closure of ventricular septal perforation and mitral replacement: a case report.

The author presents the case of a patient treated surgically for extensive myocardial infarction causing development of ventricular aneurysm, perforation of the interventricular septum and mitral regurgitation using patch-correction of the ventricular aneurysm according to Dor, exclusion repair of the ventricular perforation and retrograde replacement of the mitral valve.

Follow-Up Studies↗
PubMed1995

Pressure-induced arterial wall stress and atherosclerosis.

We present the hypothesis that high wall stress and accompanying stretch, particularly that caused by arterial pressure, are the primary factors responsible for the topography of atherosclerotic lesions. In our view the pattern in the localization of atherosclerotic lesions indicates that the artery behaves as both a pressure vessel and a conduit of blood flow. The phenomenon of "stress concentration" in the artery wall is described and the area of pressure-induced high stress is related to the sites of atherosclerotic plaques. Data are presented indicating that reduction of pressure-induced stress may lead to absence of atherosclerotic changes. The proposed mechanism explains the prevalence of atherosclerotic lesions at the ostia of major arterial branches, at the aortic bifurcation, at the carotid bifurcation, and in the descending thoracic aorta, and also explains the absence of atherosclerosis in the intramyocardial coronary arteries and in the intraosseal portions of the vertebral vessels and why a reduction in heart rate, blood pressure, or wall stress by external support reduces the occurrence of atherosclerosis. The effect of wall stress and stretch on atherosclerosis could be mediated by the endothelial cells, the smooth muscle cells, and the penetration of low-density lipoproteins. The comprehensive presentation made in this article could lead to a better understanding of atherosclerosis, its treatment, and its prevention.

Arteries↗
PubMed1995

Ischemia affects cardiac proteins in healthy animals less severely than in human patients.

BACKGROUND: Recently, our group showed that in human hearts proteins are extremely sensitive to ischemic injury. The purpose of this investigation was to evaluate the effects of ischemia on contractile and cytoskeletal proteins in rabbit and pig hearts and to compare these findings with those obtained in humans. METHODS: Rabbit hearts were arrested by perfusion with Euro-Collins solution at different temperatures. Hearts perfused with buffer served as controls. Tissue samples were incubated for varying time intervals and processed for immunohistochemistry and electron microscopy. Porcine hearts were treated in the same manner. Changes in the localization of myosin, desmin, and tropomyosin antibodies were evaluated and the degree of ischemic injury was determined by electron microscopy. RESULTS: Healthy animal hearts tolerate ischemia better than human hearts. Cardiac proteins are more sensitive to ischemia than the ultrastructural cellular organelles. Temperatures as low as 0 degree C produce more cell damage than 4 degrees C and should therefore be avoided. The Euro-Collins solution protects the myocardium better than buffer. CONCLUSIONS: We conclude that healthy animal hearts are more resistant to ischemia than diseased human hearts and that results from experimental studies should be interpreted with caution with regard to the human situation.

Animals↗
PubMed1995

Aortic spoon-jaw clamp for aorto-saphenous vein anastomosis.

In the course of coronary bypass operations the proximal anastomosis of the saphenous vein to the aorta is commonly done either with the aorta clamped completely or by using a partially occluding clamp. While under usual circumstances, either method is feasible; under other conditions, such as in the presence of partial calcification, heavy atherosclerotic deposits, or in reoperations, it is preferable not to perform either of the above methods. The purpose of this article is to present an instrument designed to allow performance of the proximal anastomosis without application of any aortic clamping in the following manner. A relatively healthy spot on the ascending aorta is selected. Under protection of a mattress suture, a stab wound is made on the aortic wall, and the lower jaw of the instrument is inserted through it into the aortic lumen. A spot is selected for the anastomotic site, the instrument is placed to that area, and its handle is closed. This effectively isolates a 10 x 8 mm area of the aortic wall from the blood flow. An opening is made in the area protected by the clamp. With the jaws of the clamp closed the vein-to-aorta anastomosis is completed as usual.

Anastomosis, Surgical↗
PubMed1995

Surgical management of instrumentation-induced coronary artery dissection.

The mechanism of instrument-induced coronary artery dissections (IICDs) is briefly presented. Depending on the coronary anatomy, three different situations that may occur are distinguished: (1) major coronary branches between the site of dissection and planned anastomosis; (2) no important collaterals at the same location; and (3) perforation of the coronary artery. Surgical methods applicable to each for the correction of these situations is presented.

Aortic Dissection↗
PubMed1995

Aortic transection secondary to rodeo injury.

Aortic transection usually occurs in the course of automobile accidents. The authors present an unusual case of aortic transection in a 27-year-old male who was thrown from a bull during a rodeo competition. Surgical repair was successful. The mechanisms of sudden deceleration and blunt impact in the pathogenesis of aortic rupture are discussed. A high index of suspicion aids in the diagnosis of unusual or subtle cases. Plain chest films may suggest the diagnosis, but aortography is currently the gold standard for establishing the diagnosis. Surgical repair is mandatory, and the use of left atrial-to-femoral bypass may lower the incidence of complications such as paraplegia and renal failure. Newer issues in the diagnosis and management of aortic transection include the use of transesophageal echocardiography and the placement of endoluminal prostheses.

Adult↗
PubMed1994

Effects of canine donor heart preservation temperature on posttransplant left ventricular function and myocardial metabolism.

The generally accepted method of preserving donor heart integrity during transfer is to arrest it with cold cardioplegic solution, then store it in a plastic bag immersed in an iced electrolyte solution. Temperatures between 0 degree C and 4 degrees C are maintained by this method until the heart is transplanted. Although profound hyperthermia best inhibits metabolic processes, it may damage the myocardium. Higher myocardial temperatures may be more advantageous and may result in better preservation. The efficacy of this hypothesis has been investigated in a canine model. The hearts of 40 dogs were isolated, arrested with cold cardioplegia, removed from the animal, and stored at different temperature ranges from 0-3 degree C to 12-15 degrees C for 4 hr. After this time period, the hearts were transplanted into a recipient animal in the cervical heterotopic position. The degree and speed of myocardial functional recovery were monitored by measuring end-systolic elastance generated from pressure-diameter loops using sonomicrometry techniques. Myocardial metabolism was studied simultaneously by monitoring coronary flow, O2, glucose, lactate, pyruvate, and free fatty acid uptakes. The results were compared with those from a control group of hearts transplanted immediately after their removal. Our results indicate that donor heart function was significantly depressed 30 min after heterotopic transplantation, but returned to "control" levels after 2 hr when stored between 0 degrees C and 6 degrees C. Myocardial function remained significantly depressed throughout the 2-hr recovery period in hearts stored at higher (6-15 degrees C) temperatures. Hearts stored at all temperatures continued to extract glucose, lactate, and free fatty acids, but produced significantly higher levels of pyruvate at higher storage temperatures, which may be related to the favored use of free fatty acids. In conclusion, donor hearts stored at colder temperatures for 4 hr regain complete left ventricular function faster than hearts stored at higher temperatures. Our experiments support the presently applied methods of donor heart preservation for 4 hr.

Animals↗
PubMed1994

Conservative operation in the management of annular dilatation and ascending aortic aneurysm.

Ascending aortic aneurysm associated with annular dilatation is generally handled by resection and replacement of the aortic root. Such an extensive operation may be avoided by a much simpler surgical intervention, ie, aortoplasty, valve replacement, and aortic wall reinforcement. Such an operation may be performed in cases where the shape of the aneurysm is a relatively regular "pear" or "teardrop" shape and is not extremely large. It also may be applied in cases of aortic stenosis with post-stenotic dilatation. The procedure requires barely more operative time and effort than a "simple" aortic valve replacement.

Aortic Aneurysm↗
PubMed1994

Hemodynamic considerations regarding the mechanism and prevention of aortic dissection.

We describe the hemodynamic principles that we postulate are responsible for the development of aortic dissection. Two types are differentiated: the "hypertensive" and the "Marfan" types. The former is characterized by moderate aortic dilatation and considerable blood pressure elevation, the latter by considerable aortic dilatation only. The role of wall stress in the development of the intimal tear and the propagation of the process of dissection are discussed. We recommend that patients who are at high risk for developing aortic dissection--those with Marfan's syndrome and dilated aortas--should undergo aortoplasty and wall reinforcement as a simple, safe, and effective way to prevent aortic dissection.

Aortic Dissection↗
PubMed1994

The freedom from atherosclerosis of intramyocardial coronary arteries: reduction of mural stress--a key factor.

The phenomenon that coronary arteries which course entirely intramyocardially remain immune to atherosclerosis was investigated in 250 patients undergoing coronary bypass surgery. In 26 the circumflex artery gave off major branches whose distal portions ran entirely intramyocardially, which required coronary bypass grafting because of proximal disease. Of these, 24 had no atherosclerosis in the intramyocardial segment, one had a calcified plaque, and one had a recanalized thrombus. The cause of this phenomenon was studied further in 14 canine hearts by measuring intramyocardial pressure. The intramyocardial pressure in the subepicardial region was as high as 63% of the left ventricular cavity pressure and in the subendocardial region it was even greater than the left ventricular cavity pressure, which indicates that the pressure gradient across the artery wall is significantly reduced, and sometimes even eliminated. It is therefore concluded that the freedom from atherosclerosis of the intramyocardial coronary arteries is due to the lack of mural stress, i.e. the lower or absent transmural pressure gradient.

Animals↗