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PubMed1998

Can retrograde perfusion mitigate cerebral injury after particulate embolization? A study in a chronic porcine model.

OBJECTIVE: We assessed the impact on histologic and behavioral outcome of an interval of retrograde cerebral perfusion after arterial embolization, comparing retrograde cerebral perfusion with and without inferior vena caval occlusion with continued antegrade perfusion. METHODS: Sixty Yorkshire pigs (27 to 30 kg) were randomly assigned to the following groups: antegrade cerebral perfusion control; antegrade cerebral perfusion after embolization; retrograde cerebral perfusion control; retrograde cerebral perfusion after embolization; retrograde cerebral perfusion with inferior vena cava occlusion, retrograde cerebral perfusion with inferior vena cava occlusion control, and retrograde cerebral perfusion with inferior vena cava occlusion after embolization. After cooling to 20 degrees C, a bolus of 200 mg of polystyrene microspheres 250 to 750 (microm diameter (or saline solution) was injected into the isolated aortic arch. After 5 minutes of antegrade cerebral perfusion, 25 minutes of antegrade cerebral perfusion, retrograde cerebral perfusion, or retrograde cerebral perfusion with inferior vena cava occlusion was instituted. After the operation, all animals underwent daily assessment of neurologic status until the time of death on day 7. RESULTS: Aortic arch return, cerebral vascular resistance, and oxygen extraction data during retrograde cerebral perfusion showed differences, suggesting that more effective flow occurs during retrograde cerebral perfusion with inferior vena cava occlusion, which also resulted in more pronounced fluid sequestration. Microsphere recovery from the brain revealed significantly fewer emboli after retrograde cerebral perfusion with inferior vena cava occlusion. Behavioral scores showed full recovery in all but one control animal (after retrograde cerebral perfusion with inferior vena cava occlusion) by day 7 but were considerably lower after embolization, with no significant differences between groups. The extent of histopathologic injury was not significantly different among embolized groups. Although no histopathologic lesions were present in either the antegrade cerebral perfusion control group or the retrograde cerebral perfusion control group, mild significant ischemic damage occurred after retrograde cerebral perfusion with inferior vena cava occlusion even in control animals. CONCLUSIONS: Although effective washout of particulate emboli from the brain can be achieved with retrograde cerebral perfusion with inferior vena cava occlusion, no advantage of retrograde cerebral perfusion with inferior vena cava occlusion after embolization is seen from behavioral scores, electroencephalographic recovery, or histopathologic examination; retrograde cerebral perfusion with inferior vena cava occlusion results in greater fluid sequestration and mild histopathologic injury even in control animals. Retrograde cerebral perfusion with inferior vena cava occlusion shows clear promise in the management of embolization, but further refinements must be sought to address its still worrisome potential for harm.

Animals↗
PubMed1994

Coronary reserve and contractile reserve in crystalloid- and blood-perfused rabbit hearts.

Coronary reserve and contractile reserve were compared between crystalloid-perfused and blood-perfused rabbit hearts at various perfusion pressures (40-110 mmHg). Contractile function of the crystalloid-perfused hearts was dependent on the perfusion pressure, according to Gregg's phenomenon. Developed left ventricular pressure (LVP) increased from 67 +/- 6 mmHg to 121 +/- 5 mmHg and positive dP/dt maximum (dP/dt max) from 1,083 +/- 75 to 2,233 +/- 126 mmHg/s at perfusion pressures between the lowest and highest perfusion pressure. In the blood-perfused hearts, the perfusion pressure-induced changes were less pronounced: developed LVP changed from 107 +/- 11 mmHg to 138 +/- 8 mmHg and dP/dt max from 1,517 +/- 181 to 2,008 +/- 187 mmHg/s. The blood-perfused hearts showed better cardiac function, especially negative dP/dt minimum (dP/dt min), compared to the crystalloid-perfused hearts. Contractile reserve estimated by paired pacing technique was quite independent of the perfusion pressure in the blood-perfused hearts but not in the crystalloid-perfused hearts, and was significantly better in the blood-perfused hearts (e.g., 81% increase of developed LVP with blood perfusion, and 26% increase with crystalloid perfusion at a perfusion pressure of 80 mmHg). Coronary reserve, estimated by reactive hyperemia, was independent of the perfusion pressure in both groups. Coronary reserve was small in the crystalloid-perfused hearts (< 23%) and more than double the control value in the blood-perfused hearts. It is proposed that blood-perfused hearts are more suitable for physiological and pathophysiological studies.

Animals↗
PubMed2000

Triphasic perfusion computed tomography in acute middle cerebral artery stroke: a correlation with angiographic findings.

OBJECTIVE: To evaluate the usefulness of triphasic perfusion computed tomography (TPCT) in diagnosing middle cerebral artery (MCA) occlusion and in assessing the perfusion deficit and collateral circulation in patients with acute ischemic stroke. BACKGROUND: Conventional angiography is the criterion standard for the diagnosis of MCA occlusion and for the assessment of perfusion deficit and collateral blood supply. The risk of hemorrhagic transformation after recanalization of occluded arteries by thrombolytic therapy is considered high when pretherapeutic residual flow is markedly reduced. PATIENTS AND METHODS: In 8 patients within 3 hours of onset of acute MCA stroke, precontrast computed tomographic scans were taken, and then TPCT was performed after power-injector controlled intravenous administration of contrast media. Sequential images of early, middle, and late phases were obtained. The whole procedure took 5 minutes. Perfusion deficit on TPCT was graded as "severe" or "moderate," depending on the state of collateral flow. Digital subtraction angiography (DSA) was performed in all patients within 6 hours of acute stroke. Direct intra-arterial urokinase infusion was begun immediately after the angiographic superselection of the MCA occlusion site in 6 of the 8 patients within 7 hours of onset (range, 4.3-6.2 hours). RESULTS: The DSA findings showed occlusion of the MCA stem (n = 1) and at the bifurcation (n = 4). The sites of proximal MCA occlusion could be identified on the early and middle images of TPCT in all 5 patients. On DSA findings, all 8 patients had a zone of perfusion deficit with markedly slow leptomeningeal collaterals and a zone of perfusion deficit with no collaterals. The zone of severe perfusion deficit on TPCT corresponded to the zone of perfusion deficit with no or few collaterals on angiography, and the zone of moderate perfusion deficit on TPCT corresponded to that of perfusion deficit with markedly slow leptomeningeal collaterals. Early parenchymal hypoattenuation on precontrast computed tomography was confined to the zone of severe perfusion deficit on TPCT. The initial National Institutes of Health Stroke Scale score correlated better with the total extent of severe perfusion deficit and moderate perfusion deficit on TPCT than that of severe perfusion deficit alone. After direct intra-arterial thrombolysis within 7 hours of onset, symptomatic hemorrhagic transformation did not develop in 4 patients with small severe perfusion deficit (33% or less of the presumed MCA territory). However, the remaining 2 patients with large severe perfusion deficit (more than 50% of the presumed MCA territory) deteriorated to death with hemorrhagic transformation. CONCLUSIONS: Triphasic perfusion computed tomography is useful for diagnosing proximal MCA occlusion and assessing perfusion deficit and collateral circulation as reliably as DSA. The zone of severe perfusion deficit on TPCT may be presumed to be the ischemic core, and that of moderate perfusion deficit, the penumbra zone. Triphasic perfusion computed tomography may be used as a rapid and noninvasive tool to make thrombolysis safer.

Acute Disease↗
PubMed1994

Experimental study of cerebral autoregulation during cardiopulmonary bypass with or without pulsatile perfusion.

Twenty-four adult mongrel dogs were divided into four equal groups according to the following method of cardiopulmonary bypass: normothermic continuous (so-called nonpulsatile) perfusion, normothermic pulsatile perfusion, hypothermic continuous perfusion, and hypothermic pulsatile perfusion. Cerebral blood flow was determined by measuring the volume of sagittal sinus venous blood outflow with a transit-time ultrasonic flowmeter. Cardiopulmonary bypass was initiated at a flow rate of 80 ml/kg per minute. Cerebral temperature was maintained at 37 degrees C in the normothermic groups and at 25 degrees C in the hypothermic groups. Arterial pH and carbon dioxide were maintained within the physiologic range by alpha-stat acid-base regulation. Mean cerebral perfusion pressure and blood flow were not affected during 90 minutes of the bypass. The respective values were 67.1 mm Hg and 37.1 ml/100 gm brain per minute with normothermic continuous perfusion, 72.8 mm Hg and 39.0 ml/100 gm per minute with nonpulsatile perfusion, 98.0 mm Hg and 23.0 ml/gm per minute with hypothermic continuous perfusion, and 86.8 mm Hg and 22.3 ml/100 gm per minute with hypothermic pulsatile perfusion. Pump flow rates were altered from 10 to 120 ml/kg per minute in a stepwise fashion to obtain graded changes of perfusion pressure. Cerebral blood flow, however, was not changed significantly by cerebral perfusion pressure so long as perfusion pressure was greater than 50 mm Hg. Conversely, cerebral blood flow changed proportionally with cerebral perfusion pressure at a pressure less than 50 mm Hg. The correlation between cerebral blood flow and perfusion pressure was described as two separate lines determined by linear regression. The slope of the regression line relating cerebral blood flow to perfusion pressure was 0.16 +/- 0.08 for a cerebral perfusion pressure above 50 mm Hg and 0.68 +/- 0.11 below 50 mm Hg in the normothermic continuous perfusion group; 0.14 +/- 0.09 and 0.32 +/- 0.09 with normothermic pulsatile perfusion; 0.10 +/- 0.04 and 0.62 +/- 0.18 with hypothermic continuous perfusion; 0.09 +/- 0.08 and 0.39 +/- 0.04 in the hypothermic pulsatile perfusion group. The slope above 50 mm Hg was significantly smaller and closer to zero in all groups than it was at a perfusion pressure below 50 mm Hg (p < 0.05).(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1977

Metabolism in the hypothermically perfused dog kidney. Utilization and production of amino acids.

The uptake and utilization of amino acids in dog kidneys during hypothermic perfusion were studied. 21 kidneys were perfused in a Gambro perfusion machine for 6 days with perfusates based on human albumin with and without addition of 17 L-amino acids. Net glucose uptake by the kidney was lower during perfusion with amino acids in the perfusate than during perfusion without amino acids. A decrease in specific activity of labelled glucose was found during perfusion with amino acids in the perfusate indicating a considerable gluconeogenesis which could explain the difference in net glucose uptake. A higher uptake of fatty acids by the kidney was found during perfusion with amino acids in the perfusate than during perfusion without amino acids. In perfusion without amino acids the concentration in the perfusate of almost all amino acids and ammonia increased and thus a net release of nitrogen was found indicating degradation of protein. In perfusion with amino acids in the perfusate a considerable uptake and release of amino acids by the kidney were found. The most pronounced uptake was registered for glutamine, proline and glycine. The most pronounced release was registered for glutamate, alanine and ammonia. During perfusion with amino acids in the medium, the uptake and release of nitrogen were balanced as distinguished from perfusion without amino acids in the perfusate.

Alanine↗
PubMed2002

Coronary perfusion methods during off-pump coronary artery bypass: results of a randomized clinical trial.

BACKGROUND: Several techniques are being used to perform off-pump coronary artery bypass (OPCAB) grafting. This three-armed clinical trial was performed to determine whether one OPCAB method of coronary perfusion was superior over the others with respect to myocardial protection and performance. METHODS: Over the course of 11 months, 151 consecutive unselected patients underwent elective first-time OPCAB grafting by sternotomy performed by a single surgeon. Patients were prospectively randomized to receive one of three OPCAB coronary perfusion treatments: (1) no coronary perfusion (NCP), ie, OPCAB using no coronary perfusion during the distal anastomosis or graft perfusion after the distal anastomosis until all the proximal anastomoses were completed; (2) passive coronary perfusion (PCP), providing distal coronary perfusion during the anastomosis and immediate graft perfusion after the distal anastomosis by means of a passive cannula from the aorta; or (3) active coronary perfusion (ACP), providing assisted distal coronary perfusion and graft perfusion by means of an in-line pump (perfusion-assisted direct coronary artery bypass. Hemodynamic and biochemical data were recorded to disc continuously throughout the operation and postoperatively. RESULTS: With no statistically significant differences in the three treatment groups with respect to patient age, left ventricular systolic or diastolic function, and extent and distribution of coronary disease or grafts performed, cardiac performance postoperatively was superior in the active coronary perfusion group compared to the groups receiving either passive coronary perfusion or no coronary perfusion (p < 0.001). In addition, troponin I levels were lower in the coronary perfusion groups (PCP and ACP) (p = 0.023). CONCLUSIONS: Providing active coronary perfusion during the anastomosis and after each distal anastomosis by using an in-line pump resulted in superior myocardial protection and performance during OPCAB surgery when compared to either no coronary perfusion or passive coronary perfusion.

Aged↗