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Biomedical subjects

F Robicsek

Publications and source records attributed to F Robicsek.

At least 145 records · Page 8Linked to original sources
PubMed1987

In vitro effect of a microfibrillar collagen hemostat on platelets.

Microscopic particles of microfibrillar collagen hemostat (MCH) have been shown to pass through a 40-micron blood transfusion filter. This study indicates that MCH passing through the filter retains a significant portion of its ability to aggregate platelets in vitro and the aggregating ability is dose related. The extent of platelet aggregation in the presence of the MCH filtrate or an ADP standard was measured photometrically and log dose-response curves constructed from the data. An ED50 of 3.6 micrograms protein/ml platelet-rich plasma (PRP) was calculated at a protein concentration of 7.6 mg/ml in the MCH filtrate and an ED50 of 5.9 micrograms protein/ml PRP at 12 mg/ml protein in the MCH filtrate. The platelet aggregating ability of the MCH filtrates corresponded to 18.8 and 39.6% of the maximum response produced by adenosine-5'-diphosphate. These findings support the view that blood contaminated with MCH should not be returned to a patient's circulation.

Adenosine Diphosphate↗
PubMed1987

Neodymium:YAG laser photocoagulation: a successful new map-guided technique for the intraoperative ablation of ventricular tachycardia.

Neodymium:YAG laser photocoagulation was used in the intraoperative treatment of drug-resistant ventricular tachycardia (VT) in 17 consecutive patients. The cause of VT was previous myocardial infarction in 15, sarcoid in one, and idiopathic in one patient. Electrophysiologic studies were performed preoperatively, before hospital discharge, and 8 to 12 weeks and 1 year after surgery. At surgery, laser photocoagulation was performed on the normothermic heart during VT. Surgical mortality was 11.7%. There was one late nonarrhythmic death 35 days postoperatively. There were 55 VT morphologies. Laser successfully abated 52 of 55. Associated use of cryoablation was required in two of 55. One VT in the patient with sarcoidosis was not successfully ablated but was controlled by procainamide. In the long-term survivors with VT due to myocardial infarction the surgical cure rate was 100%, i.e., no spontaneous or inducible VT. Follow-up ranges from 6 to 18 months (mean 11.8 +/- 4.3). Nd:YAG laser photocoagulation is an effective addition to the operative treatment strategies for VT.

Adult↗
PubMed1987

Retrograde air embolization in coronary operations.

Observations during coronary operations are presented that prove that if the ascending aorta is cross-clamped and suction applied to the left side of the heart or to the aortic root for venting purposes, the pressure rapidly drops in the coronary arterial system and a situation is created in which air may enter through the coronary arteriotomy and pass into the aortic root and the left ventricle. Another mechanism to explain the occurrence of some cases of "iatrogenic" air embolism has also been presented: introduction of air into the ascending aorta while cardioplegic solution is being injected through peripherally attached bypass grafts. Air trapped in these grafts or in the coronary artery itself may propagate proximally as well as distally in the coronary arteries and may reach the aortic root even if the left side of the heart is left unvented. These mechanisms may be responsible for heretofore unexplained cases of "iatrogenic" air embolization. We recommend careful purging of air, which may be present, from the left ventricle and aortic root every time before the aortic cross-clamp is removed during coronary operations.

Aorta↗
PubMed1986

Successful clinical laser ablation of ventricular tachycardia: a promising new therapeutic method.

This preliminary report describes 5 consecutive patients operated on for drug-resistant ventricular tachycardia (VT). All were successfully treated with laser photocoagulation ablation alone. The continuous-wave neodymium:yttrium-aluminum garnet (Nd:YAG) laser (wavelength, 1.06 micron) was chosen because of its capability for controlled deep tissue penetration, which can be adjusted by manipulating the power and exposure time of the beam. All patients had severe coronary artery disease. Preoperative left ventricular ejection fractions were low (0.18 to 0.29). Risk factors associated with increased failure rates by conventional surgical approaches were frequent: absence of discrete left ventricular aneurysm (5 patients) and multiple VT morphologies with disparate sites of origin (4 patients). All patients recovered fully. VT was not inducible prior to discharge, and no patient was placed on a regimen of antiarrhythmic drugs. Current direct surgical approaches to drug-resistant VT have markedly improved operative results compared with indirect procedures. However, failures and mortality remain high. Laser photocoagulation obviates some of the problems associated with conventional methods. It is similar to cryotherapy in that the structural integrity of affected tissues is maintained. In contrast to cryosurgery, however, laser photocoagulation is achieved more rapidly and with more precise myocardial destruction. One of the most promising features of laser coagulation is that it is administered to the perfused normothermic heart. Consequently, each morphological form of induced VT is observed to disappear as its area of origin is systematically located by mapping and then ablated.

Aged↗
PubMed1986

Long-range observations following two-stage occlusion of the descending thoracic aorta for type III dissection.

Clinical and angiographic observations have been presented in a patient with subacute dissecting aneurysms of the descending thoracic aorta (Type III) who underwent a two-stage operation. The first stage consisted of insertion of an ascending to lower abdominal aorta bypass graft through a midline incision, the second stage of exclusion of the dissected segment through a separate left thoracotomy a week later. The patient remained asymptomatic through the two years' observation period. Repeated angiograms showed persistent obliteration of the dissected segment and good flow through the aorto-aortic bypass.

Aortic Dissection↗
PubMed1986

Inherent dangers of simultaneous application of microfibrillar collagen hemostat and blood-saving devices.

Microfibrillar collagen hemostat is a topically applicable hemostatic agent that has been introduced relatively recently. Because of the possibility that this substance may pass through different blood-collecting circuits and cause organ damage if reintroduced into the patient's circulation, we performed a series of in vitro and in vivo experiments. The results of these experiments suggest that such a passage may indeed occur and could cause organ damage, either by direct or by induced embolization that cannot be completely prevented even with the application of commercially used filters. We therefore recommend that the substance should not be used if the shed blood is intended to be collected and returned into the patient's circulation.

Animals↗
PubMed1985

Patency rate of bifurcated aortic grafts: comparative analysis of woven versus knitted prostheses in the same patient.

To investigate the difference in patency rate between woven and knitted aortofemoral or aortoiliac prosthetic grafts, a special vascular prosthesis was manufactured with one limb of the graft knitted and the other, woven. The prosthesis was implanted in 143 consecutive patients with occlusive aortoiliac arteriosclerotic disease or aneurysms. Detailed statistical analysis failed to reveal any difference in the patency rate between the woven and knitted limbs of the grafts during an observation period ranging from one month to two years.

Aged↗
PubMed1985

Administration of hypothermic cardioplegia in the presence of aortic regurgitation.

Two technical maneuvers are presented to make the administration of cardioplegia feasible in the presence of moderate aortic valve incompetence. In the first maneuver, the cardioplegic solution is administered through a double-lumen balloon catheter inserted retrograde through the aortic wall and the aortic valve into the left ventricle; the inflated balloon obstructs the aortic orifice while the solution is injected through the proximal hole. In the second, after proximal anastomoses of the saphenous vein grafts are performed, the portion of the aorta from which the vein grafts rise is excluded by double cross-clamping and the cardioplegic solution is injected into this excluded segment.

Aortic Valve Insufficiency↗
PubMed1985

A simple test to determine the efficiency of mammary artery grafts during operation.

A simple test is presented to measure the efficiency of mammary artery-left anterior descending coronary artery anastomosis. While the aorta is still cross-clamped and a pronounced temperature gradient exists between the warm patient and the hypothermic heart, a thermoprobe is inserted into the apex of the heart and the flow through the mammary artery pedicle is released. Rapid warming of the cardiac apex indicates good function of the anastomosis.

Body Temperature↗
PubMed1985

An autoperfused heart-lung-preparation: metabolism and function.

The number of heart transplantations performed in the United States is increasing, and better preservation techniques are needed for distant transport and improved organ viability. Earlier experiments demonstrated that the autoperfused heart-lung preparation maintains adequate function for six to seven hours without exogenous substrates or medications. The present study evaluated the metabolic alterations at normothermia in an autoperfused heart-lung preparation and if its longevity can be extended by satisfying metabolic requirements. Thirty autoperfused heart-lung preservations were tested with an elevated buffer-bag that maintained left ventricle pressure between 75 mm Hg and 80 mm Hg. The entry and exit ports of the buffer-bag were fitted with one-way valves to insure blood circulation. Left ventricle and arterial pressure, blood pH, PCO2, PO2, glucose, free fatty acids, pyruvate and lactate were measured at regular intervals. In a first series of experiments, myocardial biopsies were taken for ATP determinations. The autoperfused heart-lung preparations were found to consume preferentially free fatty acids until their arterial level dropped to 350 +/- 24 microEq/L. Glucose then became the perferred substrate. After six to seven hours, when the glucose level dropped to 10 mg/dL, the cardiac activity stopped. In a second series, a 10% glucose solution containing 25 IU/dL of insulin was infused at a rate of 0.1 mL/min, extending the longevity of the preparation up to 18 hours. Then, the heart dilated and abruptly stopped. Massive bacterial contamination was found. When aseptic techniques were used in conjunction with antibiotics, the longevity was extended to 24 hours.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1984

Ascending-distal abdominal aorta bypass for treatment of hypoplastic aortic arch and atypical coarctation in the adult.

Repair of aortic coarctation is usually an easy operation. However, it can be very difficult under certain circumstances. These include operating on an adult or operating when specific anatomical variations, such as hypoplasia of the transverse aortic arch or calcification of the coarctation area, are present. We recommend that in such cases the situation be handled using ascending aorta-lower abdominal aorta bypass grafts rather than conventional resection and anastomosis of the coarctation itself. The cases of 2 patients are presented in whom a hypoplastic aortic arch associated with atypical coarctation was repaired using such a procedure.

Adult↗