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PubMed2004

What proportion of patients with an ostomy (for diverticulitis) get reversed?

A common operation for patients with complicated sigmoid diverticulitis is resection and placement of an ostomy (Hartmann procedure). This population-based study examines that proportion of ostomates who undergo reversal. In the California inpatient file, patients admitted for acute diverticulitis in 1995 were identified, including a subset that had surgical resection. Data regarding receipt of ostomy were obtained (4-year follow-up). Demographics and clinical data (procedure, ostomy reversal, time to reversal, comorbidity score, and complications) were collected. In 1995, 11,582 admissions for diverticulitis occurred in California. Of these, 24.2 per cent (n = 2808) underwent surgery at admission; 88.9 per cent were sigmoid/left colectomies; and 41.7 per cent had a Hartmann procedure. Patients with ostomies were older (P = 0.0004) and male (P = 0.03). Median comobidity score was the same for patients with or without an ostomy. Of the 1176 patients who had the Hartmann procedure, 65 per cent underwent reversal (mean 143 days). A larger proportion of men than women had their ostomies reversed (74.5% vs 55.9%, respectively, P < 0.0001). Median comorbidity scores for both groups were low, 0 for those reversed and 1 for nonreversed. Our study shows that although the majority of patients had their ostomies reversed, over 35 per cent did not at 4-year follow-up. Further studies are required to evaluate how this rate may be improved.

Adolescent↗
PubMed2004

[Application and review of the reversed posterior interosseous artery flap in 78 clinical cases].

OBJECTIVE: To assess and review the indications and methods of the reversed posterior interosseous artery flap for repairing soft tissue defects of the hand. METHODS: In the series, three types of flaps were utilized including the reversed posterior interosseous artery flap, the expanded reversed posterior interosseous artery flap and the reversed posterior interosseous artery conjoint flap. 78 clinical cases were treated with this method, in which 12 cases used the expanded reversed posterior interosseous artery flap and 10 cases used the reversed posterior interosseous artery conjoint flap. The flap,ranged from 8 approximately 6 cm to 14 approximately 8 cm, was used to repair the defects of the dorsal hand as far as to the fingerweb. The anatomy of the posterior interosseous artery was observed in the surgical dissection. RESULTS: The posterior interosseous artery was consistently identified in all the 78 cases. In 4 cases, the artery terminated in the middle third of the dorsal forearm, therefore an alternative method of reconstruction was used. In the 53 cases of reversed posterior interosseous flaps, 49 cases healed uneventfully and 4 cases suffered necrosis in the distal border of the flap, but subsequently healed spontaneously. 12 cases of expanded flaps survived well and the donor sites were directly approximated. In the 9 cases of conjoint flaps based on the posterior interosseous artery, 7 cases healed uneventfully and 2 cases suffered delayed healing because of flap necrosis of the distal part. The satisfactory appearance and hand function were achieved postoperatively in all cases. CONCLUSIONS: The flap is a better choice for repairing the soft tissue defects of the hand. The different type of flaps can be selected to meet the clinical requirements of reconstruction. It is suggested that the artery variation should be assessed preoperatively.

Adult↗
PubMed2005

The prevalence of reversible airflow obstruction and/or methacholine hyperreactivity in random adult asthma patients identified by administrative data.

BACKGROUND: Asthma is a chronic inflammatory lung disease. It is commonly diagnosed and treated on the basis of clinical impression, although national guidelines recommend documenting reversible airflow obstruction. OBJECTIVES: Determine the frequency of reversible airflow obstruction, and/or methacholine hyperreactivity during 2003 in a well-characterized population with a low-risk asthma diagnosis during 2001. METHODS: Of a total population of 7460 low-risk adult (18-64 years) asthma patients (no hospitalizations or emergency department visits; < 3 oral steroid courses; < 12 beta-agonist canisters; and < 3 prescibers, all in prior 12 months) cared for by a large health care program, a random sample of 400 was recruited to undergo a diagnostic asthma evaluation. The evaluation included a physical examination, medical record review, questionnaires, allergy testing, spirometry for airflow obstruction and reversibility, and/or methacholine hyperreactivity. RESULTS: Of the 400 randomly selected patients, 106 (26.5%) started and 82 (77.3%) completed the asthma evaluation. Evaluated subjects were predominately female (71%), middle-aged (mean 51.0 +/- 11.0 years), diagnosed asthmatics for long duration (mean 22.1 +/- 17.5 years), and nonsmokers (88.7%). Asthma was confirmed in 62.1% (51 of 82) based on a deltaFEV1 12% or greater after albuterol (n = 38), deltaFEV1 15% or greater after Advair (n = 6), or a positive methacholine challenge (n = 7). Only 35 of 400 patients (8.7%) ever had reversibility measured in their medical record. Of these, only 12 (34.3%) had a deltaFEV1 12% or greater after albuterol. Reversibility was confirmed in all six who had asthma evaluations. CONCLUSIONS: More than one third of low-risk adult asthmatics cannot be confirmed to have asthma 2 years later. Spirometry that documented reversibility in the medical record accurately predicted asthma confirmation. Physicians should more widely perform spirometry with reversibility to establish the diagnosis of asthma as recommended by national asthma guidelines.

Adult↗
PubMed2005

[Studies on the catalytic performance of lignin peroxidase in nonionic reversed micelles].

Lignin peroxidase (LiP) hosted in Brij 30/cyclohexane/water nonionic reversed micelle could express its catalytic activity, but in Triton X-100/n-pentanol/cyclohexane/water nonionic reversed micelle LiP didn't show any catalytic activity. Some key factors that affected the catalytic activity of LiP in Brij 30 reversed micelle were studied at 20 degrees C. The optimum conditions were:omega0 = 8.5, pH = 2.2, [Brij30] = 600 mmol/L; under these conditions the half time of LiP was ca. 50 hours. As compared with the properties of LiP in aqueous solution, the activity of LiP hosted in Brij 30 reversed micelle dropped, but its stability improved greatly. To reveal the role of normal alcohol, which was a necessary component for forming Triton X-100 reversed micelles, the effect of n-pentanol on the catalytic activity of LiP in Brij 30 reversed micelle was investigated. Results indicated that high concentration of the alcohol deactivated LiP. So it was deduced that the phenomenon that LiP hosted in the Triton X-100 reversed micelles could not express its activity was mainly due to the alcohol co-surfactant.

Catalysis↗
PubMed1990

Base mispair extension kinetics. Comparison of DNA polymerase alpha and reverse transcriptase.

A polyacrylamide gel assay is used to measure the kinetics of adding a single deoxyribonucleotide onto either a correctly matched or mismatched primer 3' terminus (on M13 template) for all possible DNA base pairs and mispairs using Drosophila melanogaster DNA polymerase alpha (Pol alpha) and avian myeloblastosis virus reverse transcriptase. The reverse transcriptase catalyzes chain extension from transition mispairs (Pur.Pyr and Pyr.Pur, where Pur is purine and Pyr is pyrimidine) more efficiently than polymerase alpha. Reverse transcriptase extends G(primer).T almost 20% as efficiently as it extends A.T, while Pol alpha's G.T extension efficiency is less than 1%. For transversion mispairs (Pur.Pur and Pyr.Pyr), reverse transcriptase extends C.T and T.T with greater efficiency than polymerase alpha, while polymerase alpha is more efficient at extending A.G and G.G mispairs. Reverse transcriptase and polymerase alpha extend the G.G mispair at an efficiency of only 10(-6) and 10(-5), respectively, compared with G.C extension. The extension data for the two polymerases are compared with previously reported nucleotide misinsertion data for the same enzymes (Mendelman, L. V., Boosalis, M. S., Petruska, J., and Goodman, M. F. (1989) J. Biol. Chem. 264, 14415-14423). While the results obtained with reverse transcriptase and Pol alpha differ in detail, some general rules are indicated: (a) Pur.Pyr and Pyr.Pur mispairs, especially G.T and T.G, are easy to insert and even easier to extend; (b) Pyr.Pyr mispairs, especially C.C, are difficult to insert and slightly easier to extend; (c) Pur.Pur mispairs, notably G.G, are harder to extend than to insert. The comparison also shows that reverse transcriptase extends almost all mismatches more efficiently than it forms them, G.G being the only mismatch having a significantly lower efficiency of extension than insertion. Polymerase alpha inserts A.A mismatches most efficiently, but extends them inefficiently, thereby reducing the probability that such transversion mutations will occur in vivo. We show theoretically that when mispaired primers compete with properly matched primers for extension by polymerase, the relative velocities of extension depend on the concentration of the next correct dNTP substrate. The extension velocities depart from Michaelis-Menten kinetics by exhibiting positive cooperativity with respect to substrate concentration.

Animals↗
PubMedDate not supplied

[Morbi-mortality of Hartmann's reversal procedure].

BACKGROUND: Hartmann's operation is an alternative for emergency colorectal surgeries, but its reversal may be difficult and prone to complications. A longer interval for its reversal has been recommended to decrease complications. METHODS: In order to determine rates of morbi-mortality and to ascertain the association between the time interval for its reversal and presence of complications, we undertook a retrospective analysis of 48 patients with a mean age of 57 +/- 16 years. Nineteen patients (40%) were >65 years, and 21 (44%) had one or more underlying chronic disease. Perioperative factors associated with morbi-mortality were determined by means of the Mann-Whitney U test and Fisher exact test. RESULTS: Acute diverticulitis was the most frequent indication (42%). Mean interval between Hartmann's operation and its reversal was 8 months (range: 1 to 46 months). Mean duration of the reversal operation was 267 min (range: 120 to 540 min). There were complications in 29 patients (60%) including anastomotic leaks in 6 (12%) and operative deaths in 4 (8%). A shorter interval between Hartmann's operation and its reversal was not associated with more complications or longer surgical time. CONCLUSIONS: Hartmann's reversal operation has high rates of morbidity and mortality that are not influenced by the time interval from the original operation.

Adult↗
PubMed1991

Prospective randomized multicenter comparison of in situ and reversed vein infrapopliteal bypasses.

We have performed a prospective, randomized, multicenter study to compare in situ and reversed vein grafts for long limb salvage bypasses from the proximal thigh to an infrapopliteal artery. Three hundred eighty-four patients required an infrapopliteal bypass for critical lower extremity ischemia. Of these, 259 were excluded because a short vein bypass was performed or because the vein was considered inadequate. The remaining 125 patients had a randomized vein bypass, 63 reversed, 62 in situ. The two groups were similar with regard to risk factors, indications, graft dimensions, and outflow. Secondary patency at 30 months was similar for both techniques: reversed 67% +/- 9% (+/- SE); in situ 69% +/- 8%. For veins less than or equal to 3.0 mm in minimum distended diameter 24-month patency rates were 61% +/- 22% for 12 in situ veins and 37% +/- 29% for 10 reversed veins (p greater than 0.05). Angiographic evaluation of failing grafts revealed lesions similar in type and frequency in both types of grafts. These included focal (in situ, n = 4; reversed, n = 7) and diffuse vein hyperplasia (in situ, n = 2; reversed, n = 1), and inflow and outflow stenoses (in situ, n = 4; reversed, n = 3). The incidence of wound complications and the mortality rate were similar for the two groups. These data show no significant difference in overall patency rates for the two types of vein grafts at 2 1/2 years.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1987

Low prevalence of particle-associated reverse transcriptase activity in serum from patients with non A - non B hepatitis.

Sera from 367 patients presumed to have NANB hepatitis were screened for reverse transcriptase activity. In 29 cases significantly increased enzyme activities could be observed. In contrast, sera from 338 patients did not contain significant reverse transcriptase activities. 207 healthy individuals, 7 patients with hepatitis A and 6 patients with hepatitis B who served as controls were all negative for reverse transcriptase activity. The specificity of the enzyme assay was demonstrated by estimation of reverse transcriptase activity in sera from 10 "healthy" HIV-1-antibody positive individuals. In 3 out of 10 cases significant reverse transcriptase activity was observed associated with the human immunodeficiency virus. Our results indicate that the presence of particle-associated reverse transcriptase activity in serum from patients with NANB hepatitis is indicative of the presence of a retrovirus-like agent in these cases. However, the relatively low prevalence of reverse transcriptase positive cases associated with the NANB hepatitis makes it rather questionable whether this agent is a frequent and specific factor in the etiology of NANB hepatitis.

Acquired Immunodeficiency Syndrome↗
PubMed1989

Human immunodeficiency virus 1 reverse transcriptase. Template binding, processivity, strand displacement synthesis, and template switching.

We have analyzed the kinetics of DNA synthesis catalyzed by reverse transcriptase from human immunodeficiency virus 1 (HIV-1). Reverse transcriptase, overproduced in Escherichia coli and purified to homogeneity, has polymerase and RNase H activity. Reverse transcriptase forms a stable complex with poly(rA).oligo(dT) primer-templates in the absence of Mg2+ and dTTP with an equilibrium dissociation constant of 3 nM. Synthesis from these preformed complexes can be initiated, and restricted to a single processive cycle, by the simultaneous addition of Mg2+, dTTP, and excess competitor RNA. Preformed complexes decay with a maximal half-life of 2-3 min. Synthesis on poly(rA) templates is processive with an incorporation rate of 10-15 nucleotides/s at 37 degrees C. Processivity varies widely with the template used, increasing from a few to greater than 300 nucleotides in the order: poly(dA) less than double-stranded DNA less than single-stranded DNA less than single-stranded RNA less than poly(rA). On double-stranded DNA reverse transcriptase catalyzes limited strand-displacement synthesis of up to 50 nucleotides. On RNA-DNA hybrids significant DNA synthesis is observed only after degradation of the RNA strand by the RNase H activity of reverse transcriptase. Intermolecular strand switching occurs with poly(rA) templates. At low ionic strength reverse transcriptase can use multiple templates with a single primer, leading to products of greater than template length. Reverse transcriptase and primer do not have to dissociate during the exchange of template strands, thus allowing processive DNA synthesis across template borders.

DNA, Single-Stranded↗
PubMed1989

Correlation between reversing of multidrug resistance and inhibiting of [3H]azidopine photolabeling of P-glycoprotein by newly synthesized dihydropyridine analogues in a human cell line.

Ten synthetic dihydropyridine analogues were investigated for their ability to reverse drug resistance in a multidrug-resistant human carcinoma cell line, KB-Cl. Four dihydropyridine analogues completely reversed the resistance, three lowered the resistance, and three had little effect. The radioactive photoactive dihydropyridine calcium channel blocker, [3H]azidopine, photolabels P-glycoprotein in membrane vesicles from KB-Cl cells. This photolabeling was almost completely inhibited by excess dihydropyridine analogues that reversed or lowered drug resistance. In contrast, the labeling was not significantly inhibited by analogues that do not reverse resistance. Among other reversing agents, cepharanthine and reserpine inhibited the [3H]azidopine photolabeling, but thioridazine did not. N-Solanesyl-N,N'-bis(3,4-dimethoxybenzyl)ethylenediamine slightly inhibited the labeling at 100 microM. An anticancer agent, vinblastine, also inhibited the labeling. The correlation between the reversing of the drug resistance and the inhibition of the [3H]azidopine photolabeling of P-glycoprotein by dihydropyridine analogues suggests a role for P-glycoprotein in multidrug resistance and also the reversing of the resistance by dihydropyridine analogues.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1986

Reverse electrical pacing improves intestinal absorption and transit time.

This study evaluates the effect of reverse electrical pacing on intestinal absorption and transit time in an enterostomy model. Twenty-five male Sprague-Dawley rats (148 to 208 gm) underwent division and anastomosis of the proximal jejunum to eliminate the proximal gastroduodenal pacemaker. A 30.0 cm loop ileostomy was formed, and leads were placed at 1.0 and 3.0 cm proximal to the stoma. Reverse pacing was done with a 0.25 Hz, 50 msec pulse at 0.1 mA. Transit time was evaluated with 1.0 ml barium gavage and was 12 +/- 4 minutes in group I controls (n = 13) versus 27 +/- 21 minutes in group II (n = 12) reverse-paced rats (p less than 0.025). D-Xylose absorption was determined in 18 rats. Levels were 14.0 +/- 3.6 mg/dl in control rats (n = 6) and 15.5 +/- 3.4 mg/dl in reverse-paced rats (n = 6). Increasing the pulse milliamperage to 2.0 mA (n = 6) increased D-xylose serum levels to 38.8 +/- 27.7 mg/dl (p less than 0.05). Transit rate and net water flux were determined in eight additional rats with 15 cm Theiry-Vella loops. Transit rate was measured with 0.2 ml of methylene blue and was 3.00 +/- 2.32 ml/min in unpaced rats compared with 9.95 +/- 0.71 ml/min with reverse pacing (p less than 0.025). Water flux studies showed that control rats had a net secretory loss of 0.20 +/- 0.48 ml/cm while paced rats absorbed 0.08 +/- 0.12 ml/cm. These data indicate that reverse electrical pacing increases transit time and nutrient and fluid absorption. These observations suggest that reverse electrical pacing may be a useful adjunct in instances of short gut associated with an enterostomy.

Animals↗
PubMed1986

Reversible inactivation of the O2-labile hydrogenases from Azotobacter vinelandii and Rhizobium japonicum.

Hydrogenases catalyze the reversible activation of dihydrogen. The hydrogenases from the aerobic, N2-fixing microorganisms Azotobacter vinelandii and Rhizobium japonicum are nickel- and iron-containing dimers that belong to the group of O2-labile enzymes. Exposure of these hydrogenases to O2 results in an irreversible inactivation; therefore, these enzymes are purified anaerobically in a fully active state. We describe in this paper an electron acceptor-requiring and pH-dependent, reversible inactivation of these hydrogenases. These results are the first example of an anaerobic, reversible inactivation of the O2-labile hydrogenases. The reversible inactivation required the presence of an electron acceptor. The rate of inactivation was first-order, with similar rates observed for methylene blue, benzyl viologen, and phenazine-methosulfate. The rate of inactivation was also dependent on the pH. However, increasing the pH of the enzyme in the absence of an electron acceptor did not result in inactivation. Thus, the reversible inactivation was not a result of high pH alone. The inactive enzyme could not be reactivated by H2 or other reductants at high pH. Titration of enzyme inactivated at high pH back to low pH was also ineffective at reactivating the enzyme. However, if reductants were present during this titration, the enzyme could be fully reactivated. The temperature dependence of inactivation yielded an activation energy of 44 kJ X mol-1. Gel filtration chromatography of active and inactive hydrogenase indicated that neither dissociation nor aggregation of the dimer hydrogenase was responsible for this reversible inactivation. We propose a four-state model to describe this reversible inactivation.

Azotobacter↗
PubMed1987

Reduced visual acuity in both eyes of monocularly deprived kittens following a short or long period of reverse occlusion.

While there can be substantial recovery of vision during reverse occlusion in the deprived eye of kittens that have been monocularly deprived from birth, in many situations this visual improvement does not appear to be retained following the introduction of binocular visual input. This study examines the consequences of periods of reverse occlusion whose onset and duration would be thought to maximize the opportunity for good and permanent recovery of vision in the initially deprived eye. Twenty kittens were monocularly deprived from near birth to either 4, 5, or 6 weeks of age and then reverse occluded for periods that were either very brief (9-18 d) or very long (9-12 weeks). In the former situation, binocular visual experience was introduced when the visual cortex was most susceptible to environmental modification, which would be thought to maximize the opportunity for the eventual development of good vision in both eyes. On the other hand, the long periods of reverse occlusion might be expected to lead to a permanent recovery of vision in only the initially deprived eye, since binocular visual input would have been introduced at a time when the cortex was no longer very plastic. Surprisingly, the end result of both these extreme regimens of reverse occlusion was the same, namely, a severe bilateral amblyopia in which the acuity of both eyes was permanently reduced to levels that were as low as 1/10, but more typically between 1/3 and 1/4 of normal values. Contrast sensitivity functions measured on 2 of the cats that received a brief period of reverse occlusion revealed deficits in contrast sensitivity of about an order of magnitude at all spatial frequencies. These observations have important implications for the nature of the physiological and anatomical changes that occur in the visual cortex during reverse occlusion.

Animals↗
PubMed1985

The behaviour of growing axons invading developing chick wing buds with dorsoventral or anteroposterior axis reversed.

The trajectories of motor axons innervating chick wings reversed about the DV or AP axis before axon invasion were analysed after retrograde filling by HRP injection into biceps or triceps muscles. Chick-quail chimaeras showed that the plane of reversal for flank operations was proximal to the confluence of the 14th, 15th, and 16th spinal roots as they form the plexus. The shoulder reversal plane was distal to the plexus. In dorsoventral (DV) reversed wings at both shoulder or flank level, the motor axons do not alter their course as they enter the graft. They therefore innervate by passive deployment any target that they encounter. In anteroposterior (AP) reversed wings at both shoulder or flank level, the motor axons clearly corrected their position in the nerve tract after entering the graft and innervated appropriate targets. The innervation of appropriate targets in AP shoulder reversals shows that axons are sensitive to AP mismatch distal to the plexus. Since axons were displaced similar distances from their normal routes in flank DV and AP reversals, the difference in behaviour suggests that they respond to mismatch in the AP but not the DV axis.

Animals↗
PubMed1995

Nitric oxide mediation of cocaine-induced dopaminergic behaviors: ambulation-accelerating activity, reverse tolerance and conditioned place preference in mice.

Intraperitoneal administration of N omega-nitro-L-arginine (L-NNA, 7.5 and 15 mg/kg), a nitric oxide synthase inhibitor, inhibited the cocaine-induced ambulation-accelerating activity and the L-NNA administered before and during the chronic injection of cocaine in mice blocked the development of reverse tolerance to the ambulation-accelerating effect of cocaine (15 mg/kg). Mice were rendered reverse tolerant to cocaine by a s.c. injection of cocaine (15 mg/kg) once daily for 6 days. The development of reverse tolerance was evidenced by an increased response to cocaine, and the inhibition of reverse tolerance was evidenced by a lesser ambulatory response. L-NNA (5 and 10 mg/kg) administered before and during cocaine conditioning inhibited the development of cocaine-induced conditioned place preference (CPP). Cocaine-induced CPP was developed by an injection of cocaine (15 mg/kg) once every other day for a 6-day period (3 times). The increase in postsynaptic dopamine receptor sensitivity was also blocked by L-NNA in both cocaine-induced reverse tolerant and CPP mice. The dopamine receptor sensitivity was increased in cocaine-induced reverse tolerant and CPP mice as evidenced by an enhanced ambulatory activity to apomorphine (2 mg/kg). Therefore, the present results suggest that these dopaminergic behaviors of cocaine may be mediated partially via the activation of the nitric oxide system and that the enhancement of postsynaptic dopamine receptor sensitivity may be an underlying common mechanism that mediates the cocaine-induced dopaminergic behaviors such as reverse tolerance and CPP.

Animals↗
PubMed1994

Sublingual isosorbide dinitrate to improve technetium-99m-teboroxime perfusion defect reversibility.

UNLABELLED: Previous studies demonstrate perfusion defect reversibility in 201Tl reinjection imaging performed after the administration of nitrates. This study tests whether the acute sublingual administration of isosorbide dinitrate (ISDN) could improve the capability of 99mTc-teboroxime to detect reversibility in exercise-induced perfusion defects. METHODS: Ten patients with previous myocardial infarction underwent exercise, redistribution and reinjection 201Tl imaging, 99mTc-teboroxime exercise and rest scans. Following the latter, 5 mg sublingual ISDN were given, 99mTc-teboroxime was reinjected and images collected. RESULTS: The total defect score/patient in the 201Tl images was 10.5 +/- 3.1 (mean +/- s.d.), decreasing to 7.4 +/- 2.7 after redistribution (p < 0.02) and to 4.8 +/- 2.1 after reinjection (p < 0.01 versus redistribution). The total defect score in 99mTc-teboroxime exercise images was 12.7 +/- 3.1 (p < 0.05 versus 201Tl exercise), decreasing to 7.3 +/- 3.3 at rest (p < 0.01 versus exercise, NS versus 201Tl redistribution) and to 5.6 +/- 2.6 in ISDN images (p < 0.02 versus rest, p < 0.05 versus 201Tl redistribution, NS versus reinjection). Of the 44 abnormal segments in 201Tl exercise images, the redistribution scan identified 26 defects as reversible and 18 as fixed. After reinjection, 37 defects appeared reversible and only seven fixed (p < 0.005 versus redistribution). Stress-rest 99mTc-teboroxime classified 33 segments as reversible and 11 as fixed (NS versus both 201Tl protocols). After ISDN, the uptake score increased in 19 segments. Therefore, 37 were classified as reversible and seven as fixed defects (p < 0.01 versus 201Tl redistribution, NS versus 201Tl reinjection). CONCLUSIONS: Sublingual ISDN before 99mTc-teboroxime rest injection seemed to improve the tracer capability of detecting reversibility in exercise-induced perfusion defects.

Administration, Sublingual↗
PubMed1994

[Superiority of the reinjection method compared with the redistribution of thallium-201 in the evaluation of reversibility after myocardial infarction].

OBJECTIVE: To assess the relative capacity of thallium-201 reinjection (RI) and redistribution (RD) for detection of reversibility in patients after myocardial infarction. DESIGN: We prospectively studied patients referred to myocardial scintigraphy for viability evaluation with stress, redistribution and reinjection images. METHODS: Patients were studied with thallium-201 SPECT using three imaging acquisitions--stress, redistribution three to four hours later and reinjection 30-60 minutes after a second injection of thallium under nitroglycerin effect. Thallium uptake was classified in a 0 to 4 intensity scale in each of 13 myocardial segments and a score obtained. Reversibility was classified as "definite" if the increase in thallium uptake was > or = 2 in a myocardial segment and as "possible" if the increase was one. PATIENTS: We studied 44 patients with previous myocardial infarction. RESULTS: The perfusion score after stress was 37.3 +/- 6.0, improving to 39.8 +/- 6.7 after redistribution and to 43.6 +/- 7.6 after reinjection (p < 0.02 between RD and RI). RD identified reversibility in 38% and RI in 63% (p < 0.001) of the 232 segments with perfusion defects. RI showed reversibility in 39% (definite in 25% and possible in 14%) of the 137 fixed perfusion defects in RD. For the detection of reversibility RI was superior to RD in all sub-groups analyzed. We found a relationship the degree of collateral circulation in the infarct related artery and the amount of reversibility in the infarcted area. CONCLUSIONS: These data suggest a clear superiority of reinjection over redistribution in thallium-201 scintigraphy for the detection of reversibility of perfusion defects after myocardial infarction, and must probably be considered as a routine procedure for myocardial viability assessment.

Adult↗
PubMed1993

[Reversibility in perfusion scintigraphy after myocardial infarct: a comparison between the protocol of single-day rest-stress with 99mTc sestamibi and reinjection with thallium-201].

OBJECTIVE: To compare thallium-201 stress-reinjection SPECT (TL) and single-day rest-stress 99mTc-sestamibi SPECT (MIBI) for detection of reversibility of perfusion defects after Q-wave myocardial infarction. DESIGN: Prospective study with the two scintigraphic methods. PATIENTS: We studied 31 patients with previous Q-wave myocardial infarction referred for assessment of myocardial viability. METHODS: Patients were studied with thallium-201 stress-reinjection SPECT and single-day rest-stress 99mTc-sestamibi SPECT. Tracer uptake was classified in a 0 to 4 intensity scale in each of 13 myocardial segments. RESULTS: Segmental comparison indicated that the identification of perfusion defects was similar by the two methods. Some reversibility was present in 51% of TL perfusion defects and in 26% of MIBI perfusion defects (p < 0.001). Twenty-seven percent of fixed perfusion defects in MIBI showed some reversibility by TL, but only 8% of the fixed perfusion defects by TL were reversible by MIBI (p < 0.001). In infarct-related perfusion defects, TL showed reversibility in 46% and MIBI in 22% (p < 0.001). TL detected reversibility in 84% of patients and MIBI in 48% (p = 0.007). CONCLUSIONS: Although the two methods were similar for perfusion defects identification, the present study suggests that thallium-201 reinjection is superior to single-day rest-stress 99mTc-sestamibi for the detection of reversibility. Clinical relevance of these differences, as a marker of viability, requires further evaluation of these patients after successful revascularization.

Adult↗