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PubMedDate not supplied

Tirofiban administration attenuates platelet and platelet-neutrophil conjugation but not neutrophil degranulation during in vitro VAD circulation.

Ventricular Assist Devices (VADs) have been used as bridges to heart transplantation. However, VAD circulation is complicated by the incidence of thromboembolism, prolonged bleeding, and activation of the inflammatory cascade. We hypothesize that platelet and neutrophil activation are interrelated and linked to the activation of the glycoprotein (GP) IIb/IIIa platelet receptor. The purpose of this study is to evaluate the effects of Tirofiban, a platelet GP IIb/IIIa receptor inhibitor, on platelet and neutrophil activation during simulated VAD circulation. Two groups of five in vitro VAD circuits were simulated with and without Tirofiban using 450 cc of human blood. Blood samples were drawn at specific time intervals up to 72 hours, measuring leukotriene C4 (LTC4), platelet factor four (PF4), and neutrophil elastase. Tirofiban decreased serum levels of PF4 and LTC4 during VAD circulation. Neutrophil elastase secretion was not affected by Tirofiban administration. Preconditioning of VAD circulation with Tirofiban attenuated platelet activation as demonstrated by a decrease in serum PF4 levels. Tirofiban administration ameliorates the inflammatory response by altering platelet-neutrophil interaction as demonstrated by a decrease in LTC4 production. Continued elastase secretion indicates that the inflammatory response is not completely inhibited by Tirofiban administration. These results suggest that neutrophils may be activated by alternative mechanisms. Early complement activation has been demonstrated during in vivo and in vitro VAD circulation and may play a role in mediating inflammatory and thromboembolic reactions during VAD use.

Blood Platelets↗
PubMed1990

[Cross circulation (CC) as an assist method for canine orthotopic cardiac transplantation--estimation of usefulness judging from intra- and postoperative hematological and biochemical examinations].

We employed cross circulation (CC) as an assist method for canine orthotopic cardiac transplantation in 8 dogs to obtain long term survivals. Hematological and biochemical examinations were performed intra- and postoperatively, to estimate usefulness of CC. The support dog weighted about 3 times as much as the recipient dog. Using different anesthesia, the systolic pressure of the support dog and the pressure gradient between the support and recipient were kept above 150 mmHg and 50 mmHg, respectively. Cyclosporin and prednisolone were administered for immunosuppressive therapy. All could be extubated on the 1st to 3rd postoperative day, and 6 survived more than 2 weeks. During the operation under CC, changes of LDH and lactic acid were much less, no free hemoglobin was detected, and total protein and hematocrit remained well compared with operation under heart-lung machines. CRK, CPKMB, GOT and GPT increased shortly after operation, but returned to the preoperative values within 2 weeks. In CC, owing to avoidance from mechanical destruction of red blood cells, coagulation disorders and hemodilution, hemolysis and hemorrhage could be decreased, and oncotic pressure remained well, and no severe damage occurred in the recipient organs. Thus, CC is useful as an assist method for canine orthotopic cardiac transplantation.

Animals↗
PubMed1983

Mechanical assistance of the pulmonary circulation after right ventricular exclusion.

The Fontan procedure is often associated with elevated right-sided pressures and low cardiac output during the early postoperative period. A dog model was established to test the effect of pulmonary artery counterpulsation after atriopulmonary anastomosis. After exclusion of the right ventricle by a purse-string suture at the right AV orifice, placed during inflow occlusion, a valved conduit was inserted between the right atrial appendage and the pulmonary artery. This created a circulatory pattern comparable to a Fontan procedure. Counterpulsation was achieved by inserting a cannula into the conduit distal to the valve in eight dogs; alternatively, in four, counterpulsation could be achieved through a 10 mm side-arm graft connected to the conduit distal to the valve. Twenty-four observations were made. Without counterpulsation the circulatory status of the dog deteriorated rapidly. Counterpulsation resulted in a mean increase in cardiac output of 48% (p less than 0.0001). Right atrial pressure fell significantly with a mean drop of 4 mm Hg (p less than 0.003). This allowed for a further increase in right-sided filling pressure by transfusion, with a subsequent further increase in cardiac output. Left atrial pressure did not change significantly unless altered by transfusion. Counterpulsation instituted through the 10 mm side-arm graft gave similar results. Pulmonary vascular resistance decreased with counterpulsation (mean decrease 35%; p less than 0.002). The use of a side-arm graft connected to the conduit after a Fontan procedure affords a clinical method of circulatory support without the need for additional surgical intervention for decannulation. These data suggest that mechanical assistance of the failing right atrium after atriopulmonary anastomosis is both feasible and effective.

Animals↗
PubMed2003

Characterization of platelet-specific mRNA by real-time PCR after laser-assisted microdissection.

Circulating anucleate platelets contain minute amounts of residual megakaryocytic-derived mRNA. To study cell type-specific gene expression in platelets, an accurate and sensitive method to detect and quantify platelet mRNA that excludes contamination with leukocyte RNA is mandatory. Applying laser-assisted microdissection and manipulation (LMM) we could isolate platelets from hemalaun-stained cytospins under permanent visual control and after laser-photolysis of nucleated blood cells. For mRNA quantification, the platelet-specific mRNAs were subsequently measured by real time RT-PCR. High-copy beta3 integrin and low-copy a alpha2 integrin as well as tissue factor (TF) transcripts were analyzed in LMM-harvested platelets. In 91.2% (83/91) beta3 integrin was detectable with a mean threshold cycle (CT) value of 32.5+/-3.2 (< or =50,000 cells). The low-copy a 2 integrin mRNA was positive in 84.4% (38/45) with CT mean value of 36.9+/-1.3, indicating that the relative expression of alpha2 integrin mRNA in platelets was about 130 times lower than beta3. The TF transcript was undetectable in all samples. Comparing platelet mRNA from LMM isolation to that from limiting dilution series resulted in a high accordance for beta3 integrin transcript in both, recovery (91.2% vs. 95.2%) and CT value (32.5 vs. 32.8). These results demonstrate that the combination of LMM and real-time RT-PCR is a valuable tool for precise, platelet-specific mRNA analysis without contamination of other cells.

Blood Platelets↗
PubMedDate not supplied

A single skeletal muscle powered ventricle that assists both systemic and pulmonary circulations.

Extraaortic counterpulsation using skeletal muscle powered ventricles (SMPVs) has been studied mainly for the purpose of assisting the systemic circulation. The purpose of this study was to investigate the possibility of assisting both the systemic and pulmonary circulations using a single SMPV. An SMPV that counterpulses the systemic circulation is placed beside the right atrium (RA) or the right ventricle (RV), the former after procedures such as a Fontan operation, and the latter in cases of biventricular failure. Because the SMPV dilates passively during cardiac systole, it is designed to press the RA or the RV directly from outside. This study is a preliminary report, and only the ability of a specially constructed SMPV to dilate was assessed. Using seven dogs with heart failure, the SMPV dilated with an internal pressure of 88 mmHg and 1.0 cm, while the volume inside increased by 10.8 ml. From these results, it is suggested that the SMPV has enough dilating power to press the RA or to assist the RV while counterpulsing the systemic circulation.

Animals↗
PubMed1966

Relation of mechanical circulatory support to myocardial function and energy utilization.

Evaluation of the influence of mechanical circulatory support, with the goal of improving techniques, requires quantification of those variables which determine cardiac performance. Characterization of myocardial function in terms of preload, afterload, stroke work and stroke power, velocity of contraction and frequency of contraction can be accomplished with instrumentation available in the catheterization laboratory. Similarly, the influence of mechanical circulatory support on the metabolic activity of the heart can be quantitatively assessed. Utilization of these measurements to evaluate current techniques should facilitate the development of improved methods for assisting the circulation.

Animals↗
PubMed2004

Endoscope-assisted microneurosurgery for anterior circulation aneurysms using the angle-type rigid endoscope over a 3-year period.

INTRODUCTION: The use of the endoscope (fiberscope) to assist the microsurgical clipping of cerebral aneurysm was first reported by Fischer and Mustafa in 1994. The rigid endoscope has been increasingly used during aneurysm surgery in which structures around the aneurysm can be detected with high quality imaging. Our 3 years of its use now allows us to assess the endoscope's efficacy and limits in standard surgery with a pterional approach in aneurysms of the anterior circulation. The endoscope can carry out a supportive role in planning surgical manoeuvres and in verifying whether clipping has been performed correctly or not. In our view, among the aneurysms of the anterior circulation, the endoscope is particularly useful in those of the internal carotid and the anterior communicating arteries. In many cases of these aneurysms the posterior communicating artery, choroidal artery or one of the distal cerebral arteries is hidden behind the aneurysm dome. Dome retraction is often required in order to see these vascular structures with the microscope. Thus an endoscope with a 30 degrees view angle becomes very useful. The concealed areas are identified without retraction, which prevents the possibility of the aneurysm being ruptured and also reduces the use of temporary clipping. From its early use as a supportive measure that is sometimes useful in surgery for "easy" aneurysms, the endoscope has now become almost indispensable for the "difficult" aneurysms, including the large and giant ones before and after clipping. Thus, the endoscope should be kept ready for use in the operating theatre for any eventuality. OBJECTIVE: We assess the advantages and disadvantages of the use of the endoscope in the microsurgical treatment of intracranial aneurysms. METHODS: During our 3 years of experience, 52 patients with 48 ruptured and 10 unruptured aneurysms of the anterior circulation (including 6 cases of two-fold aneurysms) underwent clipping with endoscope support through a pterional approach. All ruptured aneurysms produced a Hunt and Hess Grade I or II subarachnoid haemorrhage. The endoscope was inserted before and after clipping in order to observe the conditions surrounding the aneurysm and to receive immediate confirmation that clipping had been performed correctly. RESULTS: In all cases general anatomy visualization was provided by the endoscope, and the correct clip positioning and vessel conditions were easily checked. In 4 cases the endoscope showed that the clip had been positioned incorrectly. Additional clipping was performed in these cases: in 2 cases the clip was re-applied correctly and in another case a clip was added. Only the fourth patient with a large communicating artery died (1.9%) of cerebral infarction. This was due to post-clipping stenosis of one distal cerebral artery in which it was not possible to re-position the clip correctly because of the presence of arteriosclerotic calcific plaque near the aneurysm neck. In 3 cases there was an intraoperative ruptured aneurysm dome that was not caused by the endoscope insertion. No further complications were caused by the endoscope. CONCLUSION: In certain cases endoscopic-assisted microsurgery is an exceptional aid to the surgeon and must become part of the operating theatre equipment and kept on hand ready for use. The endoscope is, in our opinion, particularly useful in certain aneurysm localisations (internal carotid artery-anterior communicating artery [ICA-ACOMA]).

Adult↗
PubMed1991

The trauma of suction-assisted lipectomy cannula on flap circulation in rats.

The effect of suction-assisted lipectomy on cutaneous blood vessels of inguinal skin flaps was studied and compared in 191 rats. Different types of cannula tips were used; the number of passes was standardized. In one experiment, following suctioning, 3 X 2 cm groin island flaps based on inferior epigastric pedicles were raised and then reattached. Fluorescein dye study and microangiography were performed to evaluate flap viability. Flap survival was determined clinically and by histologic examination on the fifth postoperative day. Three-sided inguinal random-pattern flaps were raised in a second experiment and reattached following suctioning. On the fifth postoperative day, surviving flap areas were measured using standard photographs and an imaging computer and were compared with controls. Results showed that cannula passes accompanied by vacuum are harmful to vessels, while those unaccompanied by vacuum are not. The greater the number of suctioning passes, the more trauma there is to vessels and the greater is the likelihood of flap necrosis. Conical and spatula tips were more harmful to vessels than spherical, cobra, keel cobra, or Fournier tips. These results support the conclusion that suction-assisted lipectomy enhances the possibility of skin necrosis by traumatizing the vascular pedicle of a flap, especially when it is used as an adjunct to flap elevation.

Animals↗
PubMed1989

Use of an intraaortic balloon pump as a pneumatic ventricular assist device controller.

Using a circulatory analogue, we investigated sequentially the performance of a dedicated ventricular assist device driver and an intraaortic balloon pump when driving a pneumatic ventricular assist device. Each drive device was compared under identical pumping conditions at rates of 40 to 120 cycles/min against two resistances. Our preliminary study showed that a modified intraaortic balloon pump could drive a pneumatic ventricular assist device as effectively as its dedicated driver. The necessary modifications to and possible further development of the intraaortic balloon in this role are discussed.

Assisted Circulation↗
PubMed1985

A sterile, delayed-closure technique for placement of a left ventricular assist device.

A simplified technique of left ventricular assist device placement using Silastic sheeting attached to the presternal fascia and skin is described. This technique allows viewing of cardiac action and prevents cardiac compression by sternal closure. Removal of the assist device is simple because the sternum does not have to be reopened.

Assisted Circulation↗