Effect of the effluent released from the canine internal mammary artery after intraluminal and extraluminal perfusion of acetylcholine and adenosine diphosphate

Segments of the canine internal mammary artery (35 mm in length) were suspended in vitro in an organ chamber containing physiological salt solution (95% O(2)/5% CO(2), pH = 7.4, 37 degrees C). Segments were individually cannulated and perfused at 5 ml/minute using a roller pump. Vasorelaxant activity of the effluent from the perfused internal mammary arteries was bioassayed by measuring the decrease in tension induced by the effluent of the coronary artery endothelium-free ring which had been contracted with prostaglandin F(2 alpha) (2 x 10(-6) M). Intraluminal perfusion of adenosine diphosphate (10(-5) M) induced significant increase in relaxant activity in the effluent from the perfused blood vessel. However, when adenosine diphosphate (10(-5) M) was added extraluminally to the internal mammary artery, no change in relaxant activity in the effluent was noted. In contrast, acetylcholine produced significant increase in the relaxant activity on the effluent of the perfused internal mammary artery with both intraluminal and extraluminal perfusion. The intraluminal and extraluminal release of endothelium-derived relaxing factor (EDRF) by acetylcholine (10(-5) M) can be inhibited by site-specific administration of atropine (10(-5) M). These experiments indicate that certain agonists can induce the release of EDRF only by binding to intravascular receptors while other agonists can induce endothelium-dependent vasodilatation by acting on neural side receptors.

Can tissue drug concentrations be monitored by microdialysis during or after isolated limb perfusion for melanoma treatment?

Isolated limb perfusion (ILP) with melphalan is used to treat recurrent melanoma. This study aimed to develop a microdialysis technique for melphalan tissue concentration measurement during ILP. The effects of melphalan concentration (50-600 mu g/ml), microdialysis flow rate (0.55-17.5 mu l/min), probe length (5-50 mm) and temperature (25-41.5 degrees C) on in vitro recovery were studied. In addition, in vivo recovery was measured in rat hindlimbs perfused with melphalan using 50 mm microdialysis probes implanted subcutaneously and into muscle. Both dialysate and tissue sample melphalan concentrations were determined by high performance liquid chromatography. The in vitro recovery of melphalan was not affected by melphalan concentration or temperature, but increased with probe length and decreased with flow rate. The melphalan concentrations in subcutaneous and muscle dialysates were not significantly different. A linear relationship was found between tissue dialysate concentrations and actual tissue concentrations of melphalan (r(2) = 0.97). Microdialysis is a potential method for tissue drug monitoring which may assist in the efficacious use of cytotoxics in human ILP. (C) 2000 Lippincott Williams & Wilkins.

Refining the perfusion-diffusion mismatch hypothesis

Background and Purpose-The Echoplanar Imaging Thrombolysis Evaluation Trial ( EPITHET) tests the hypothesis that perfusion-weighted imaging (PWI)-diffusion-weighted imaging (DWI) mismatch predicts the response to thrombolysis. There is no accepted standardized definition of PWI-DWI mismatch. We compared common mismatch definitions in the initial 40 EPITHET patients. Methods-Raw perfusion images were used to generate maps of time to peak (TTP), mean transit time (MTT), time to peak of the impulse response (Tmax) and first moment transit time (FMT). DWI, apparent diffusion coefficient ( ADC), and PWI volumes were measured with planimetric and thresholding techniques. Correlations between mismatch volume (PWIvol-DWIvol) and DWI expansion (T2(Day) (90-vol)-DWIAcute-vol) were also assessed. Results-Mean age was 68 +/- 11, time to MRI 4.5 +/- 0.7 hours, and median National Institutes of Health Stroke Scale (NIHSS) score 11 (range 4 to 23). Tmax and MTT hypoperfusion volumes were significantly lower than those calculated with TTP and FMT maps (P < 0.001). Mismatch >= 20% was observed in 89% (Tmax) to 92% (TTP/FMT/MTT) of patients. Application of a +4s ( relative to the contralateral hemisphere) PWI threshold reduced the frequency of positive mismatch volumes (TTP 73%/FMT 68%/Tmax 54%/MTT 43%). Mismatch was not significantly different when assessed with ADC maps. Mismatch volume, calculated with all parameters and thresholds, was not significantly correlated with DWI expansion. In contrast, reperfusion was correlated inversely with infarct growth (R= -0.51; P = 0.009). Conclusions-Deconvolution and application of PWI thresholds provide more conservative estimates of tissue at risk and decrease the frequency of mismatch accordingly. The precise definition may not be critical; however, because reperfusion alters tissue fate irrespective of mismatch.

Description of a New Model of Intestinal Denervation and In Situ Ischemia-Reperfusion Injury Using the Cecal Artery for Perfusion

Background. The main purpose of the present investigation was to describe a model of intestinal denervation and in situ intestinal ischemia-reperfusion injury in adult rats, with utilization of the distal branch of the superior mesenteric artery close to the cecum for perfusion. Methods. In the root of the mesentery, the mesenteric artery and vein were completely isolated. Close to the cecal valve, a lymphatic node served as the reference point for the localization of the cecal artery, which was cannulated for perfusion with cold lactated Ringer`s solution. One hundred adult male rats were utilized in the study. Results. In a pilot study, we demonstrated that the cold ischemia time was sufficient to promote histopathologic intestinal changes characteristic of ischemia-reperfusion injury. Among 88 operated animals, 62 (70.5%) survived the procedure. Conclusion. The experimental model described herein has the advantage of preserving the entire intestine, which makes it more suitable for studies of physiological and morphological alterations after intestinal transplantation.

Diagnostic Performance of Combined Noninvasive Coronary Angiography and Myocardial Perfusion Imaging Using 320-MDCT: The CT Angiography and Perfusion Methods of the CORE320 Multicenter Multinational Diagnostic Study

OBJECTIVE. Coronary MDCT angiography has been shown to be an accurate noninvasive tool for the diagnosis of obstructive coronary artery disease (CAD). Its sensitivity and negative predictive value for diagnosing percentage of stenosis are unsurpassed compared with those of other noninvasive testing methods. However, in its current form, it provides no information regarding the physiologic impact of CAD and is a poor predictor of myocardial ischemia. CORE320 is a multicenter multinational diagnostic study with the primary objective to evaluate the diagnostic accuracy of 320-MDCT for detecting coronary artery luminal stenosis and corresponding myocardial perfusion deficits in patients with suspected CAD compared with the reference standard of conventional coronary angiography and SPECT myocardial perfusion imaging. CONCLUSION. We aim to describe the CT acquisition, reconstruction, and analysis methods of the CORE320 study.

An optimized model for rat liver perfusion studies

Conditions which influence the viability, integrity, and extraction efficiency of the isolated perfused rat liver were examined to establish optimal conditions for subsequent work in reperfusion injury studies including the choice of buffer, use of oncotic agents, hematocrit, perfusion flow rate, and pressure. Rat livers were perfused with MOPS-buffered Ringer solution with or without erythrocytes. Perfusates were collected and analyzed for blood gases, electrolytes, enzymes, radioactivity in MID studies, and lignocaine in extraction studies. Liver tissue was sampled for histological examinations, and wet:dry weight of the liver was also determined. MOPS-buffered Ringer solution was found to be superior to Krebs bicarbonate buffer, in terms of pH control and buffering capacity, especially during any prolonged period of liver perfusion. A pH of 7.2 is chosen for perfusion since this is the physiological pH of the portal blood. The presence of albumin was important as an oncotic agent, particularly when erythrocytes were used in the perfusate. Perfusion pressure, resistance, and vascular volume are how-dependent and the inclusion of erythrocytes in the perfusate substantially altered the flow characteristics for perfusion pressure and resistance but not vascular volume. Lignocaine extraction was relatively flow-independent. Perfusion injury as defined by enzyme release and tissue fine structure was closely related to the supply of O-2. The optimal conditions for liver perfusion depend upon an adequate supply of oxygen. This can be achieved by using either erythrocyte-free perfusate at a how rate greater than 6 ml/min/g liver or a 20% erythrocyte-containing perfusate at 2 ml/min/g. (C) 1996 Academic Press, Inc.

Dipyridamole Stress and Rest Myocardial Perfusion by 64-Detector Row Computed Tomography in Patients With Suspected Coronary Artery Disease

Recently, stress myocardial computed tomographic perfusion (CTP) was shown to detect myocardial ischemia. Our main objective was to evaluate the feasibility of dipyridamole stress CTP and compare it to single-photon emission computed tomography (SPECT) to detect significant coronary stenosis using invasive conventional coronary angiography (CCA; stenosis >70%) as the reference method. Thirty-six patients (62 +/- 8 years old, 20 men) with previous positive results with SPECT (<2 months) as the primary inclusion criterion and suspected coronary artery disease underwent a customized multidetector-row CT protocol with myocardial perfusion evaluation at rest and during stress and coronary CT angiography (CTA). Multidetector-row computed tomography was performed in a 64-slice scanner with dipyridamole stress perfusion acquisition before a second perfusion/CT angiographic acquisition at rest. Independent blinded observers performed analysis of images from CTP, CTA, and CCA. All 36 patients completed the CT protocol with no adverse events (mean radiation dose 14.7 +/- 3.0 mSv) and with interpretable scans. CTP results were positive in 27 of 36 patients (75%). From the 9 (25%) disagreements, 6 patients had normal coronary arteries and 2 had no significant stenosis (8 false-positive results with SPECT, 22%). The remaining patient had an occluded artery with collateral flow confirmed by conventional coronary angiogram. Good agreement was demonstrated between CTP and SPECT on a per-patient analysis (kappa 0.53). In 26 patients using CCA as reference, sensitivity, specificity, and positive and negative predictive values were 88.0%, 79.3%, 66.7%, and 93.3% for CTP and 68.8, 76.1%, 66.7%, and 77.8%, for SPECT, respectively (p = NS). In conclusion, dipyridamole CT myocardial perfusion at rest and during stress is feasible and results are similar to single-photon emission CT scintigraphy. The anatomical-perfusion information provided by this combined CT protocol may allow identification of false-positive results by SPECT. (C) 2010 Elsevier Inc. All rights reserved. (Am J Cardiol 2010;106:310-315)

Isolated limb perfusion with melphalan for human melanoma xenografts in the hindlimb of nude rats: A surviving animal model

We have established a surviving model of isolated limb perfusion using xenografts of the human melanoma cell line MM 96L injected subcutaneously into the hindlimb of a nude rat, The femoral artery and vein were cannulated via the left renal artery and vein and the hind limb was isolated using tourniquets. The limb was perfused with Krebs Heinseleit buffer at 37 degrees C containing 4.7% bovine serum albumin at a constant flow rate of 4 mi per min for 30-60 min with 100% survival of the animals, Tumour vascularization and blood flow were demonstrated using vascular casts and [Cr-51]-microspheres. Following the addition of melphalan (15 or 100 mu g/ml), drug concentrations in the perfusate, tissues and systemic circulation were determined using high pressure liquid chromatography (HPLC), Systemic leakage, assessed using [I-125]albumin and melphalan and detected by a gamma-counter and HPLC respectively, was <0.5%. The melphalan concentration and tissue flow rate in the tumour deposits were 40 and 30% respectively, when compared with the surrounding subcutaneous tissue, At a dose of 15 mu g/ml, melphalan caused a reduction in tumour growth after 60 min perfusion, and a significant reduction in tumour size was seen when the melphalan dose was 100 mu g/ml. The surviving nude rat model of isolated limb perfusion for recurrent melanoma will allow examination of optimal perfusion conditions, along with the pharmacokinetics, pharmacodynamics and efficacy of melphalan and other drugs.

Comparison Between Perfadex and Locally Manufactured Low-Potassium Dextran Solution for Pulmonary Preservation in an Ex Vivo Isolated Lung Perfusion Model

Introduction. Lung tranplantation, a consolidated treatment for end-stage lung disease, utilizes preservation solutions, such as low potassium dextran (LPD), to mitigate ischemia reperfusion injury. We sought the local development of LPD solutions in an attempt to facilitate access and enhance usage. We also sought to evaluate the effectiveness of a locally manufactured LPD solution in a rat model of ex vivo lung perfusion. Methods. We randomized the following groups \?\adult of male Wistar rats (n = 25 each): Perfadex (LPD; Vitro life, Sweden); locally manufactured LPD-glucose (LPDnac) (Farmoterapica, Brazil), and normal saline solution (SAL) with 3 ischemic times (6, 12, and 24 hours). The harvested heart lung blocks were flushed with solution at 4 C. After storage, the blocks were connected to an IL-2 Isolated Perfused Rat or Guinea Pig Lung System (Harvard Apparatus) and reperfused with homologous blood for 60 minutes. Respiratory mechanics, pulmonary artery pressure, perfusate blood gas analysis, and lung weight were measured at 10-minute intervals. Comparisons between groups and among ischemic times were performed using analysis of variance with a 5% level of significance. Results. Lungs preserved for 24 hours were nonviable and therefore excluded from the analysis. Those preserved for 6 hours showed better ventilatory mechanics when compared with 12 hours. The oxygenation capacity was not different between lungs flushed with LPD or LPDnac, regardless of the ischemic time. SAL lungs showed higher PCO(2) values than the other solutions. Lung weight increased over time during perfusion; however, there were no significant differences among the tested solutions (LPD, P = .23; LPDnac, P = .41; SAL, P = .26). We concluded that the LPDnac solution results in gas exchange were comparable to the original LPD (Perfadex); however ventilatory mechanics and edema formation were better with LPD, particularly among lungs undergoing 6 hours of cold ischemia.

Melphalan dosing regimens for management of recurrent melanoma by isolated limb perfusion: Application of a physiological pharmacokinetic model based on melphalan distribution in the isolated perfused rat hindlimb

The optimal dosing schedule for melphalan therapy of recurrent malignant melanoma in isolated limb perfusions has been examined using a physiological pharmacokinetic model with data from isolated rat hindlimb perfusions (IRHP), The study included a comparison of melphalan distribution in IRHP under hyperthermia and normothermia conditions. Rat hindlimbs were perfused with Krebs-Henseleit buffer containing 4.7% bovine serum albumin at 37 or 41.5 degrees C at a flow rate of 4 ml/min. Concentrations of melphalan in perfusate and tissues were determined by high performance liquid chromatography with fluorescence detection, The concentration of melphalan in perfusate and tissues was linearly related to the input concentration. The rate and amount of melphalan uptake into the different tissues was higher at 41.5 degrees C than at 37 degrees C. A physiological pharmacokinetic model was validated from the tissue and perfusate time course of melphalan after melphalan perfusion. Application of the model involved the amount of melphalan exposure in the muscle, skin and fat in a recirculation system was related to the method of melphalan administration: single bolus > divided bolus > infusion, The peak concentration of melphalan in the perfusate was also related to the method of administration in the same order, Infusing the total dose of melphalan over 20 min during a 60 min perfusion optimized the exposure of tissues to melphalan whilst minimizing the peak perfusate concentration of melphalan. It is suggested that this method of melphalan administration may be preferable to other methods in terms of optimizing the efficacy of melphalan whilst minimizing the limb toxicity associated with its use in isolated limb perfusion.

Myocardial Perfusion Imaging Is a Strong Predictor of Death in Women

OBJECTIVES We sought to assess the prognostic value and risk classification improvement using contemporary single-photon emission computed tomography myocardial perfusion imaging (SPECT-MPI) to predict all-cause mortality. BACKGROUND Myocardial perfusion is a strong estimator of prognosis. Evidence published to date has not established the added prognostic value of SPECT-MPI nor defined an approach to detect improve classification of risk in women from a developing nation. METHODS A total of 2,225 women referred for SPECT-MPI were followed by a mean period of 3.7 +/- 1.4 years. SPECT-MPI results were classified as abnormal on the presence of any perfusion defect. Abnormal scans were further classified as with mild/moderate reversible, severe reversible, partial reversible, or fixed perfusion defects. Risk estimates for incident mortality were categorized as <1%/year, 1% to 2%/year, and >2%/year using Cox proportional hazard models. Risk-adjusted models incorporated clinical risk factors, left ventricular ejection fraction (LVEF), and perfusion variables. RESULTS All-cause death occurred in 139 patients. SPECT-MPI significantly risk stratified the population; patients with abnormal scans had significantly higher death rates compared with patients with normal scans, 13.1% versus 4.0%, respectively (p < 0.001). Cox analysis demonstrated that after adjusting for clinical risk factors and LVEF, SPECT-MPI improved the model discrimination (integrated discrimination index = 0.009; p = 0.02), added significant incremental prognostic information (global chi-square increased from 87.7 to 127.1; p < 0.0001), and improved risk prediction (net reclassification improvement = 0.12; p = 0.005). CONCLUSIONS SPECT-MPI added significant incremental prognostic information to clinical and left ventricular functional variables while enhancing the ability to classify this Brazilian female population into low-and high-risk categories of all-cause mortality. (J Am Coll Cardiol Img 2011;4:880-8) (C) 2011 by the American College of Cardiology Foundation

Changes in Perfusion-Weighted Magnetic Resonance Imaging after Carotid Angioplasty with Stent

Carotid artery stenosis due to arteriosclerosis increases the risk of cerebral ischemia via embolic phenomena or reduced blood flow. The changes in cerebral perfusion that may occur after treatment are not clearly understood. This study evaluated the changes in cerebral microcirculation following carotid angioplasty with stenting (CAS) under cerebral protection with filters using ultrafast gradient echo (GRE) perfusion weighted imaging (PWI) with magnetic resonance imaging (MRI). Prospectively, 21 cervical carotid stenosis patients, mean age 69.95 years, underwent MRI 12 h before and 72 h after CAS. PWI parameters were collected for statistical analysis: cerebral blood volume (CB V), mean transit time (MTT) and time to peak (TTP). Statistical analysis was applied to absolute parameters and to values normalized against those from the contralateral parenchyma. The main finding of this study was improved hemodynamics for the normalized data after CAS, shown by reduced MTT (p<0.001) and TTP (p=0.019) in the territory fed by the middle cerebral artery ipsilateral to the CAS. Absolute data showed increased blood volume in the cerebral hemispheres after CAS, which was more accentuated on the stent side (p=0.016) than the contralateral side (p=0.029). Early improvements in cerebral perfusion, mainly seen in the normalized data, were clearly demonstrated in the timing parameters - TTP & MTT - after CAS.

Ex Vivo Lung Perfusion: Early Report of Brazilian Experience

Introduction. Only about 15% of the potential candidates for lung donation are considered suitable for transplantation. A new method for ex vivo lung perfusion (EVLP) can be used to evaluate and recondition ""marginal,"" nonacceptable lungs. We have herein described an initial experience with ex vivo perfusion of 8 donor lungs deemed nonacceptable. Materials and Methods. After harvesting, the lungs were perfused ex vivo with Steen Solution, an extracellular matrix with high colloid osmotic pressure. A membrane oxygenator connected to the circuit received gas from a mixture of nitrogen and carbon dioxide, maintaining a normal mixed venous blood gas level in the perfusate. The lungs were gradually rewarmed, reperfused, and ventilated for evaluation through analyses of oxygenation capacity, pulmonary vascular resistance (PVR), lung compliance (LC), and biopsy. Results. The arterial oxygen pressure (with inspired oxygen fraction of 100%) increased from a mean of 206 mm Hg in the organ donor at the referring hospital to a mean of 498 mm Hg during the ex vivo evaluation. After 1 hour of EVLP, PVR varied from 440-1454 dynes/sec/cm(5); LC was in the range of 26-90 mL/cmH(2)O. There was no histological deterioration after 10 hours of cold ischemia and 1 hour of EVLP. Conclusions. The ex vivo evaluation model can improve oxygenation capacity of ""marginal"" lungs rejected for transplantation. It has great potential to increase lung donor availability and, possibly, reduce time on the waiting list.

Changes in Myocardial Perfusion Correlate With Deterioration of Left Ventricular Systolic Function in Chronic Chagas` Cardiomyopathy

OBJECTIVES This study aimed at analyzing the association between myocardial perfusion changes and the progression of left ventricular systolic dysfunction in patients with chronic Chagas` cardiomyopathy (CCC). BACKGROUND Pathological and experimental studies have suggested that coronary microvascular derangement, and consequent myocardial perfusion disturbance, may cause myocardial damage in CCC. METHODS Patients with CCC (n = 36, ages 57 +/- 10 years, 17 males), previously having undergone myocardial perfusion single-positron emission computed tomography and 2-dimensional echocardiography, prospectively underwent a new evaluation after an interval of 5.6 +/- 1.5 years. Stress and rest myocardial perfusion defects were quantified using polar maps and normal database comparison. RESULTS Between the first and final evaluations, a significant reduction of left ventricular ejection fraction was observed (55 +/- 11% and 50 +/- 13%, respectively; p = 0.0001), as well as an increase in the area of the perfusion defect at rest (18.8 +/- 14.1% and 26.5 +/- 19.1%, respectively; p = 0.0075). The individual increase in the perfusion defect area at rest was significantly correlated with the reduction in left ventricular ejection fraction (R = 0.4211, p = 0.0105). Twenty patients with normal coronary arteries (56%) showed reversible perfusion defects involving 10.2 +/- 9.7% of the left ventricle. A significant topographic correlation was found between reversible defects and the appearance of new rest perfusion defects at the final evaluation. Of the 47 segments presenting reversible perfusion defects in the initial study, 32 (68%) progressed to perfusion defects at rest, and of the 469 segments not showing reversibility in the initial study, only 41 (8.7%) had the same progression (p < 0.0001, Fisher exact test). CONCLUSIONS In CCC patients, the progression of left ventricular systolic dysfunction was associated with both the presence of reversible perfusion defects and the increase in perfusion defects at rest. These results support the notion that myocardial perfusion disturbances participate in the pathogenesis of myocardial injury in CCC. (J Am Coll Cardiol Img 2009;2:164-72) (c) 2009 by the American College of Cardiology Foundation