Viabilidade miocárdica na prática clínica / Assessing myocardial viability in clinical practice

Embora a avaliação da viabilidade miocárdica seja comum na prática do cardiologista, muitos médicos têm dúvidas a respeito dos resultados dos métodos diagnósticos. A medicina nuclear tem papel importante nos estudos de viabilidade, mas os laudos precisam ser interpretados num contexto clínico e fisiopatológico. Este artigo teve o objetivo de revisar a origem e a evolução do conceito da viabilidade miocárdica. São expostos os métodos diagnósticos com ênfase na medicina nuclear com uma explicação funcional sobre cada tipo de exame. A partir disso, são mostradas imagens como exemplos e é proposta uma maneira de atuar nesses casos baseada na clínica, na porcentagem de miocárdio acometido e na topografia das lesões coronarianas (proximais ou distais). (AU)

Although assessing myocardial viability is a common cardiology practice, many physicians question the results of diagnostic methods. Nuclear medicine plays an important role in viability studies, but the reports require interpretation in a clinical and pathophysiological context. this article was aimed at reviewing the origin and evolution of myocardial viability. Here we present diagnostic methods by emphasizing nuclear medicine and provide a functional explanation of each test type using example images. We also propose how to act in these cases based on clinic examination findings, the percentage of affected myocardium, and coronary lesion topography (proximal or distal).(AU)

Clinical utility of left ventricular ejection fraction reserve by stress thallium-201 myocardial gated single photon computed tomography among patients with and suspected coronary artery disease

BACKGROUND: Coronary microcirculation impairment with sequential decrease in cardiac function is reflected by abnormal left ventricular ejection fraction reserve (LVEFR),which precedes diagnostic evidence of myocardial insult. However, prognostic utility of LVEFR is less, if not least explored. The aim of this study was to evaluate the clinical utility of LVEFR in predicting major cardiac events (MACE) among patients with and suspected coronary artery disease (CAD).MATERIALS AND METHODS: A retrospective cohort study of 245 patients who underwent stress thallium-201 myocardial perfusion scan (MPS) was conducted. The patients were categorized as having normal or abnormal perfusion scan. Each group was subdivided into normal and abnormal LVEFR groups. All subjects were followed up for any major adverse cardiac events 36 months after MPS through review of hospital records.RESULTS: There was an overall increase in the likelihood of cardiac events with abnormal LVEFR (i.e., odds ratio of 2.99,p=CONCLUSION: Abnormal LVEFR can be used as an independent predictor of cardiac events which can be observed in subjects with normal and abnormal perfusion scans alike.

Clinical utility of left ventricular ejection fraction reserve by stress thallium-201 myocardial gated single photon computed tomography among patients with and suspected coronary artery disease

BACKGROUND: Coronary microcirculation impairment with sequential decrease in cardiac function is reflected by abnormal left ventricular ejection fraction reserve (LVEFR),which precedes diagnostic evidence of myocardial insult. However, prognostic utility of LVEFR is less, if not least explored. The aim of this study was to evaluate the clinical utility of LVEFR in predicting major cardiac events (MACE) among patients with and suspected coronary artery disease (CAD).MATERIALS AND METHODS: A retrospective cohort study of 245 patients who underwent stress thallium-201 myocardial perfusion scan (MPS) was conducted. The patients were categorized as having normal or abnormal perfusion scan. Each group was subdivided into normal and abnormal LVEFR groups. All subjects were followed up for any major adverse cardiac events 36 months after MPS through review of hospital records.RESULTS: There was an overall increase in the likelihood of cardiac events with abnormal LVEFR (i.e., odds ratio of 2.99,p=CONCLUSION: Abnormal LVEFR can be used as an independent predictor of cardiac events which can be observed in subjects with normal and abnormal perfusion scans alike.

Value of Tl-201 imaging in predicting therapeutic I-131 uptake in patients with thyroglobulin-positive but I-131 scan negative differentiated thyroid cancer

BACKGROUND: Serum thyroglobulin assays and I-131 imaging and routinely employed for the detection of remaining functioning thyroid tissue after surgery and radioiodine therapy. However, the sensitivity of I-131 is suboptimal resulting in cases of positive thyroglobulin test but negative I-131 imaging, potentially creating a dilemma in subsequent therapeutic management. Other radiopharmaceuticals, such as TI-201 may offer better sensitivity, although it is not clear whether this contributes to the decision-making for subsequent I-131therapy. This prospective cohort study aimed to determine if Tl-201 imaging identified thyroid tissues that will take up therapeutic I-131, and to help define its clinical utility.METHODS: Fourteen consecutive patients who underwent surgery for well-differentiated thyroid cancer, had I-131 therapy at least eight months previously, and with elevated thyroglobulin (>10 ng/mL) but negative pre-therapy (111 MBq) I-131 whole body scan (WBS), were enrolled in the study. WBS was done using 56.74 MBq of Tl-201. All patients had repeat I-131 ablation (3.7-7.4GBq) one to two months after Tl-201 imaging. Post-therapy WBS was done four to seven days after.RESULTS: All 14 patients had papillary thyroid carcinoma. Ten patients had a positive Tl-201 scan. Of the 14 subjects, only two had a positive post-therapy I-131 WBS, both whom had a positive Tl-201 scan. Thallium-201 scanning showed a fairly high sensitivity (71%) in demonstrating thyroid remnants or metastases using a thyroglobulin level of >10 ng/mL as standard. However, a positivel Tl-201 scan only has a predictive value of 20% for subsequent uptake of therapeutic I-131 as shown in the post-therapy scan.CONCLUSION: Thallium-201 uptake correlates poorly with therapeutic I-131 uptake in thyroglobulin-positive, but I-131 scan-negative, differentiated thyroid cancer patients. Results of this study suggest that the presence of thyroid remnants and metastases on Tl-201 imaging is inappropriate as a basis for subsequent I-131 therapy.

Value of Tl-201 imaging in predicting therapeutic I-131 uptake in patients with thyroglobulin-positive but I-131 scan negative differentiated thyroid cancer

BACKGROUND: Serum thyroglobulin assays and I-131 imaging and routinely employed for the detection of remaining functioning thyroid tissue after surgery and radioiodine therapy. However, the sensitivity of I-131 is suboptimal resulting in cases of positive thyroglobulin test but negative I-131 imaging, potentially creating a dilemma in subsequent therapeutic management. Other radiopharmaceuticals, such as TI-201 may offer better sensitivity, although it is not clear whether this contributes to the decision-making for subsequent I-131therapy. This prospective cohort study aimed to determine if Tl-201 imaging identified thyroid tissues that will take up therapeutic I-131, and to help define its clinical utility.METHODS: Fourteen consecutive patients who underwent surgery for well-differentiated thyroid cancer, had I-131 therapy at least eight months previously, and with elevated thyroglobulin (>10 ng/mL) but negative pre-therapy (111 MBq) I-131 whole body scan (WBS), were enrolled in the study. WBS was done using 56.74 MBq of Tl-201. All patients had repeat I-131 ablation (3.7-7.4GBq) one to two months after Tl-201 imaging. Post-therapy WBS was done four to seven days after.RESULTS: All 14 patients had papillary thyroid carcinoma. Ten patients had a positive Tl-201 scan. Of the 14 subjects, only two had a positive post-therapy I-131 WBS, both whom had a positive Tl-201 scan. Thallium-201 scanning showed a fairly high sensitivity (71%) in demonstrating thyroid remnants or metastases using a thyroglobulin level of >10 ng/mL as standard. However, a positivel Tl-201 scan only has a predictive value of 20% for subsequent uptake of therapeutic I-131 as shown in the post-therapy scan.CONCLUSION: Thallium-201 uptake correlates poorly with therapeutic I-131 uptake in thyroglobulin-positive, but I-131 scan-negative, differentiated thyroid cancer patients. Results of this study suggest that the presence of thyroid remnants and metastases on Tl-201 imaging is inappropriate as a basis for subsequent I-131 therapy.

Survey of canine tick-borne diseases in Lábrea, Brazilian Amazon: ‘accidental’ findings of Dirofilaria immitis infection / Pesquisa de agentes transmitidos por carrapatos em cães de Lábrea, Amazonas: achados “acidentais” de Dirofilaria immitis

Blood samples were collected from 99 domestic dogs from the urban and rural areas of the Lábrea municipality, state of Amazonas, Brazil. Canine serum samples were tested by immunofluorescence assay against Rickettsia spp., which revealed that only 3.0% (1/33) and 7.6% (5/66) of the dogs from urban and rural areas, respectively, reacted positively to at least one Rickettsia species. DNA was extracted from canine blood and tested by a battery of PCR assays targeting protozoa of the genera Babesia and Hepatozoon, and bacteria of the genera Rickettsia and Ehrlichia and family Anaplasmataceae. All samples were negative in the PCR assays targeting the genera Babesia, Hepatozoon, Ehrlichia and Rickettsia. For Anaplasmataceae, 3% (1/33) and 39.4% (26/66) of the urban and rural dogs, respectively, yielded amplicons that generated DNA sequences 100% identical to the corresponding sequence of Wolbachia endosymbiont of Dirofilaria immitis. Because of these results, all canine DNA samples were further tested in a PCR assay targeting filarial nematodes, which was positive for 18.2% (6/33) and 57.6% (38/66) urban and rural dogs, respectively. Filarial-PCR products generated DNA sequences 100% identical to D. immitis. While tick-borne infections were rare in Lábrea, D. immitis infection rates were among the highest reported in South America.

Amostras de sangue foram coletadas de 99 cães domésticos de áreas urbana e rural do município de Lábrea, estado do Amazonas. Soros caninos foram testados pela técnica de imunofluorescência indireta contra Rickettsia spp., resultando em apenas 3,0% (1/33) e 7,6% (5/66) de cães soropositivos nas áreas urbana e rural, respectivamente. DNA foi extraído do sangue canino e testado por diferentes protocolos da PCR para detecção de protozoários dos gêneros Babesia e Hepatozoon, e bactérias dos gêneros Rickettsia e Ehrlichia e da família Anaplasmataceae. Todas as amostras foram negativas nos protocolos de PCR para os gêneros Babesia, Hepatozoon, Ehrlichia e Rickettsia. Para Anaplasmataceae, 3% (1/33) e 39,4% (26/66) dos cães de áreas urbana e rural, respectivamente, geraram sequências de DNA 100% idênticas ao endosimbionte Wolbachia de Dirofilaria immitis. Posteriormente, as amostras foram testadas pela PCR para nematódeos filarídeos, resultando em 18,2% (6/33) e 57,6% (38/66) de amostras positivas nas áreas urbana e rural, respectivamente. Os produtos geraram sequências de DNA 100% idênticas a D. immitis. Em contraste com várias outras regiões do Brasil, infecções transmitidas por carrapatos foram raras em Lábrea. Por outro lado, as frequências de infecção por D. immitis estiveram entre as mais altas relatadas na América do Sul.

Serial myocardial imaging after a single dose of Thallium-201

Although thallium-201 exercise scintigraphy has been established for the detection of myocardial ischemia and viability, little is known regarding the myocardial thallium-201 kinetics during angioplasty. Herein, we report a 77-year old man with angina pectoris, in whom serial myocardial imaging after a single dose of thallium-201 was helpful in identifying not only the culprit lesion and myocardial viability, but also the dynamic changes in myocardial perfusion during angioplasty. Thallium-201 images after exercise showed a perfusion defect in the inferior wall, with a trivial redistribution 3 hours after the exercise and a marked improvement 24 hours later. Coronary angiography, performed 27 hours after exercise scintigraphy, showed severe stenosis in the right coronary artery. Guidewire crossing of the lesion interrupted the antegrade flow, which was restored after balloon dilation and stent implantation. Thallium-201 images, 2 hours after angioplasty [i.e., 30 hours after exercise], showed a decreased tracer uptake in the inferior wall, which improved the next day [i.e., 48 hours after exercise]. Cardiac biomarkers were negative in the clinical course

Occupational Neurotoxic Diseases in Taiwan

Occupational neurotoxic diseases have become increasingly common in Taiwan due to industrialization. Over the past 40 years, Taiwan has transformed from an agricultural society to an industrial society. The most common neurotoxic diseases also changed from organophosphate poisoning to heavy metal intoxication, and then to organic solvent and semiconductor agent poisoning. The nervous system is particularly vulnerable to toxic agents because of its high metabolic rate. Neurological manifestations may be transient or permanent, and may range from cognitive dysfunction, cerebellar ataxia, Parkinsonism, sensorimotor neuropathy and autonomic dysfunction to neuromuscular junction disorders. This study attempts to provide a review of the major outbreaks of occupational neurotoxins from 1968 to 2012. A total of 16 occupational neurotoxins, including organophosphates, toxic gases, heavy metals, organic solvents, and other toxic chemicals, were reviewed. Peer-reviewed articles related to the electrophysiology, neuroimaging, treatment and long-term follow up of these neurotoxic diseases were also obtained. The heavy metals involved consisted of lead, manganese, organic tin, mercury, arsenic, and thallium. The organic solvents included n-hexane, toluene, mixed solvents and carbon disulfide. Toxic gases such as carbon monoxide, and hydrogen sulfide were also included, along with toxic chemicals including polychlorinated biphenyls, tetramethylammonium hydroxide, organophosphates, and dimethylamine borane. In addition we attempted to correlate these events to the timeline of industrial development in Taiwan. By researching this topic, the hope is that it may help other developing countries to improve industrial hygiene and promote occupational safety and health care during the process of industrialization.

Occupational Neurotoxic Diseases in Taiwan

Occupational neurotoxic diseases have become increasingly common in Taiwan due to industrialization. Over the past 40 years, Taiwan has transformed from an agricultural society to an industrial society. The most common neurotoxic diseases also changed from organophosphate poisoning to heavy metal intoxication, and then to organic solvent and semiconductor agent poisoning. The nervous system is particularly vulnerable to toxic agents because of its high metabolic rate. Neurological manifestations may be transient or permanent, and may range from cognitive dysfunction, cerebellar ataxia, Parkinsonism, sensorimotor neuropathy and autonomic dysfunction to neuromuscular junction disorders. This study attempts to provide a review of the major outbreaks of occupational neurotoxins from 1968 to 2012. A total of 16 occupational neurotoxins, including organophosphates, toxic gases, heavy metals, organic solvents, and other toxic chemicals, were reviewed. Peer-reviewed articles related to the electrophysiology, neuroimaging, treatment and long-term follow up of these neurotoxic diseases were also obtained. The heavy metals involved consisted of lead, manganese, organic tin, mercury, arsenic, and thallium. The organic solvents included n-hexane, toluene, mixed solvents and carbon disulfide. Toxic gases such as carbon monoxide, and hydrogen sulfide were also included, along with toxic chemicals including polychlorinated biphenyls, tetramethylammonium hydroxide, organophosphates, and dimethylamine borane. In addition we attempted to correlate these events to the timeline of industrial development in Taiwan. By researching this topic, the hope is that it may help other developing countries to improve industrial hygiene and promote occupational safety and health care during the process of industrialization.

[Compensation of cross-contamination in simultaneous 201Tl/99mTc myocardial perfusion SPECT imaging]

It is a common protocol to use 201Tl for the rest and 99mTc for the stress cardiac SPECT imaging. Theoretically, both types of imaging may be performed simultaneously using different energy windows for each radionuclide. However a potential limitation is the cross-contamination of scattered photons from 99mTc and collimator X-rays into the 201Tl energy window. We used a middle energy window method to correct this cross-contamination. Using NCAT, a typical software torso phantom was generated. An extremely thin line source of 99mTc activity was placed inside the cardiac region of the phantom and no activity in the other parts. The SimSET Monte Carlo simulator was used to image the phantom in different energy windows. To find the relationship between projections in different energy windows, deconvolution theory was used. We investigated the ability of the suggested functions in three steps: Monte Carlo simulation, phantom experiment and clinical study. In the last step, SPECT images of eleven patients who had angiographic data were acquired indifferent energy windows. All of these images were compared by determining the contrast between a defect or left ventricle cavity and the myocardium. We found a new 2D kernel which had an exponential pattern with a much higher center. This function was used for modeling 99mTc down scatter distribution from the middle window image. X-ray distribution in the 201Tl window was also modeled as the 99mTc photopeak image convolved by a Gaussian function. Significant improvements in the contrast of the simultaneous dual 201Tl images were found in each step before and after reconstruction. In comparison with other similar methods, better results were acquired using our suggested functions. Our results showed contrast improvemtn in thallium images after correction, however, many other parameters should be evaluated for clinical approaches. There are many advantages in simultaneous dual isotope imaging. It halves imaging time and reduces patient waiting time and discomfort. Identical rest/stress registration of images also facilitates physicists' motion or attenuation corrections and physicians' image interpretation

study of demographic and clinical features of patients referred to the nuclear medicine department of a military hospital for myocardial perfusion scintigraphy

It seems that demographic and clinical features of patients referred for myocardial perfusion scintigraphy [MPS] is different among populations and healthcare settings. The purpose of the current study is to evaluate the clinical features and risk factors of patients referred for myocardial perfusion scintigraphy to a military hospital. As a cross-sectional study, the clinical and laboratory data of all patients who were referred for MPS were recorded. MPS was performed using [99m]Tc-Sestamibi or Thallium-201 [Tl-201] as the radiotracer. From March 2005 to March 2006, the data of 1392 consecutive patients were recorded. The mean age of the patients was 55.3 +/- 14.8 years. 45.6% of the patients had no major risk factor, while 38.5% had one and 15.9% had two risk factors. Hypertension was the most common risk factor, while cigarette smoking was reported by eight percent of the patients. The method of stress protocol was dipyridamole infusion in 69.2%, Treadmill exercise test in 28.4% and dobutamine infusion in 2.4% of the cases. The sensitivity, specificity, positive predictive value, negative predictive value and overall accuracy of MPS in detection of angiographically positive CAD were 88.5%, 71.4%, 94.3%, 46.8% and 75.3%, respectively. In our population hypertension is the most frequent risk factor, so extensive social programs should be implemented aiming at controlling this variable, in order to prevent its possible cardiac complications. Cigarette smoking is less common than general population, which could be due to social characteristics of the target community and their beliefs, so this distinctiveness should be well defined and promoted. The differences in the pattern of cardiovascular symptoms and risk factors can be considered as indirect evidences to the fact that the pattern of referral for MPS in our country is significantly different from those in developed countries, a fact that warrants further evaluation in order to confirm its appropriateness based on the validated international guidelines

Correlation between 64-slice CT angiography and conventional coronary angiography

64-slice CT coronary angiography is now available as a valuable technology in evaluating patients, both with and without symptoms for the detection of coronary lesions and in making decision whether or not further invasive testing is needed. The aim of our study was to evaluate the diagnostic performance of 64-slice CT angiography for detection of significant coronary artery stenoses in comparison with conventional coronary angiography. During a period of 20 months [April 2007-November 2008] we studied 565 patients with 64-slice CT angiography of coronary arteries who fulfilled following criteria; having a positive stress test such as thallium-scan or stress echocardiography if symptomatic, sinus heart rhythm and able to hold breath for 15 seconds. We scheduled coronary angiography for 58 of these patients with mean age of 52 +/- 10.5 years [37 men and 21 women] who have one or more significant stenoses of coronary arteries. A significant lesion was assumed if the diameter reduction of vessel was = 50%. The overall sensitivity and specificity of 64-slice CT for detection of significant coronary artery stenoses in this study were 95% and 94% respectively. The positive predictive value was 85% and negative predictive value was 94%. We found that 64-slice CT correctly identified all patients with three vessel disease. This technique was reliable to classify 90% of patients [52/58] as having one, two or three vessel disease correctly. In conclusion 64-slice CT coronary angiography has a high degree of both sensitivity and specificity in detection of significant coronary artery stenoses

Use of exercise tolerance test and thallium stress test in the diagnosis of ischemic heart disease in soldiers

To determine the role of Exercise Tolerance Test [ETT] and Thallium Stress Test [TST] in the detection of Coronary Artery Disease [CAD] among soldiers. Descriptive study. This study was conducted at Combined Military Hospital [CMH], Multan, Pakistan, from 2002 to 2004. There were 291 male soldiers between ages 30 and 45 years who presented with chest pain and had normal resting ECG. All patients were subjected to ETT. Positive ETT cases had Coronary Angiogram [CA] as the gold standard. Negative cases were subjected to TST. Normal CA cases also had TST to rule out microvascular disease. Those with normal ETT and positive CAD risk factors also had TST. Those with negative TST had CA as service requirement. All 291 cases had ETT, 130 cases were found positive, 161 had negative ETT. When CA was done on 130 positive cases, 95 had CAD [true positive, TP] and 35 had normal coronaries [false positive, FP]. Out of the 161 negative ETT cases, 128 had normal coronaries [true negative, TN] and 33 had CAD [false negative, FN]. TST was conducted on 196 cases, out of which 78 cases were found positive and 118 had negative TST. When subjected to CA, out of 78 positive cases, 30 had CAD [TP] and 48 had normal coronaries [FP]. Out of 118 negative TST cases, 115 had normal coronaries [TN] and 3 had CAD [FN]. ETT was found to have sensitivity of 74.2%, specificity of 78.5%, Positive Predictive Value [PPV] of 73.1%, Negative Predictive Value [NPV] of 79.5% and test accuracy of 76.6%. TST had sensitivity of 90.9%, specificity of 70.6%, PPV of 38.5%, NPV of 97.5% and accuracy of 74.0%. TST was found to be more sensitive and less specific than ETT in the diagnosis of CAD

Myoview [technetium-99m tetrofosmine] scintigraphy of parathyroid gland in primary hyperparathyroidism

Minimal surgical techniques are increasingly used to remove parathyroid adenomas. Such surgery depends on accurate preoperative localization of the parathyroid swelling. The preoperative accuracy of Tc-99m tetrofosmin was evaluated in 45 patients presented with primary hyperparathyroidism and compared with ultrasonography and Tc-99m pertechnetate studies / Thallium-201 [Tc-O[4]/TL-20I] subtraction. The overall sensitivity of Tc-99m tetrofosmin was 88.8% for double phase study and 91.1% for dual tracer subtraction and that for Tc-99mO[4]/TL-201 subtraction was 80% and US was 73.3% with high significant difference. High reliability and accuracy of Tc-99m tetrofosmin in pre-operative localization of parathyroid adenoma

Thallium poisoning, Iraq

Two Iraqi families developed symptoms of thallium poisoning after consuming a meal on January 21st. Patients have been transferred to Amman for care at the Jordanian Hospitals. The Poison Laboratory in Baghdad had detected thallium in specimens taken from patients and foods. Ten family members were identified as cases; all presented with abdominal pain, vomiting and dysphagia. Within 4 days, 9 [90%] case-patients developed lower extremity pain and paresthesis and hair loss. Three case-patients died and one is clinically dead [case fatality rate=40%]. Median onset of illness was 24 hours [range: 12-72 hours]. WHO has sent blood, urine and cake specimens to Birmingham; Toxicology Laboratory to confirm and measure the concentration of Thallium in different specimens [according to IATA regulations to ensure the safe delivery of the specimens]; and facilitated procurement of Prussian blue antidote through contacting the UK Department of Health as it was not available in Jordan and neighboring countries. Intentional contamination is suspected and a legal investigation by authorities in Baghdad is underway. Information and results from this investigation are still pending. [Source: A report from WHO Office, Iraq]

Incremental prognostic value of perfusion defects in patients with scintigraphic evidence of left ventricular dysfunction

Patients with LV dysfunction are known to have a high risk for future coronary events. This study aimed to determine the incremental prognostic value of perfusion defects in patients with scintigraphic evidence of LV dysfunction. Patients showing either transient ischemic dilatation or Tl-201 lung:heart ratio of >0.5 on exercise or dipyridamole SPECT Tl- 201 myocardial perfusion scan were included in the study. Perfusion defects were scored semiquantitatively using a 17 -segment, 5-point scale (0 = normal, 4 = absent uptake). The extent and severity of defects were quantified using number of abnormal segments (NAS) and the summed stress score (SSS). Defect reversibility was quantified using the summed difference score (SDS) between stress and rest defects. Patients were followed up for the development of coronary events over a period of 12 - 30 months. There were 6 cardiac deaths and 7 myocardial infarctions in the 65 patients included in the study (20% overall event rate). ROC curve analysis of the scores revealed the following suggested cut-off values for predicting cardiac event: NAS ~ 7 (85% sensitivity, 56% specificity), SSS ~ 19 (77% sensitivity, 67% specificity) and SDS ~ 7 (31 % sensitivity, 60% specificity). ,Event rate was significantly higher above the cut-off value in SSS «19 = 9%, >19 = 32%,p = 0.04). With NAS, the event rate was higher above the cut-off value, with the difference approaching significance (NAS 7 = 26%, P = 0.06). There was no statistically significant difference in the event rate with high or low SDS (SDS 7 = 16%, P = 0.32). The odds ratios for NAS and SSS (5.8,4.9, respectively) were higher compared with SDS (0.56). The extent and severity of stress perfusion defects provided incremental prognostic information in patients with LV dysfunction. Our data suggest that the degree of defect reversibility showed no prognostic value in this subset of patients.

Protective effect of selenium against the thallium or mercury-induced oxidative stress in rats

In the present study, the possible protective effect of sodium selenite [250. microg/kg] against thallium nitrate [3 mg/kg] and mercuric acetate [1.5 mg/kg] induced oxidative stress was studied in rats. The measured parameters were lipid peroxides [measured as MDA] and lactate dehydrogenase activity [LDH] in serum, liver and kidney. The effects of thallium nitrate and mercuric acetate as well as the combination of each of them with sodium selenite were determined on the aforementioned parameters. Results of the present study showed that thallium nitrate as well as mercuric acetate significantly increased lipid peroxides in serum, liver and kidney. Administration of sodium selenite together with thallium nitrate or mercuric acetate resulted in significant decrease in lipid peroxides in serum, liver and kidney thus exerting significant protection against thallium and mercury-induced oxidative stress Thallium nitrate significantly elevated lactate dehydrogenase activity [LDH] in serum, liver and kidney while mercuric acetate significantly, elevated LDH activity only in serum and liver. Sodium selenite significantly antagonized the effect of thallium and mercury and protected against their toxicity. It could be concluded that sodium selenite can effectively protect against thallium and mercury- induced oxidative stress

Significance of perfusion defects on dipyridamole thallium cardiac SPECT in patients with left bundle branch block

Left Bundle Branch Block [LBBB] is a known cause of false positive results in myocardial perfusion studies. We aimed at investigation of correlation between degree of severity of perfusion defect on cardiac Single Photon Emission Computed Tomography [SPECT] and presence of coronary artery disease on angiography in patients with LBBB. This was an analytical study and was carried out at Department of Nuclear Cardiology and Department of Cardiac Catheterisation of Punjab Institute of Cardiology, Lahore from January 2007 to April 2007. In this study patients having LBBB without known coronary artery disease [CAD] referred for myocardial perfusion studies to the Nuclear Cardiology Department from outpatient, indoor and emergency departments were included. Thallium201 stress/rest Single-Photon Emission Tomography [SPECT] acquisition scanning was performed. The myocardial perfusion pattern was classified as normal, fixed defect and reversible defect. Coronary angiography was used to confirm CAD only in patients with abnormal scan. Thirty consecutive patients having LBBB were studied. All patients underwent myocardial perfusion imaging using dipyridamole pharmacologic stress. Fourteen patients [47%] revealed normal Thallium201 uptake and distribution at the septum. Reversible defects were noted in 13 [43%] patients. Fixed defects were noted in 3 [10%] patients. Among four patients with mild perfusion defects only 1 [25%] had significant coronary artery disease. In patients with moderate perfusion defects, coronary angiogram was positive for significant coronary artery disease in 1 [33%] patient. In six patients having severe perfusion defects significant coronary artery disease was noted in 5 [83%] patients. All patients with fixed defects had significant coronary artery disease. False positive studies were found to be significantly greater in patients with reversible defects particularly with mild to moderate defects. Conclusions: Patients with left bundle branch block showing moderate to severe reversible perfusion defects on dipyridamole thallium cardiac SPECT have high likelihood of coronary artery disease

Thallium poisoning presenting as paresthesias, paresis, psychosis and pain in abdomen.

Due to involvement of multiple systems, thallium poisoning is notorious for complexity and seriousness as symptoms of toxicity are non-specific and diverse. Alopecia and painful neuropathy are its cardinal features, others being gastrointestinal disturbances, encephalopathy, tachycardia, ataxia, hepatorenal and cardiac damage etc. We report a case of thallium poisoning who presented initially with gastrointestinal symptoms and later developed neurological features (peripheral neuropathy and delirium). Various diagnoses were entertained in this case and thallium poisoning was suspected only after he developed alopecia and neuropsychosis. He made a significant recovery by conservative management in spite of delay in diagnosis. We conclude that a high level of suspicion should be kept for thallium poisoning, especially in patients with painful, peripheral neuropathy and gastrointestinal symptoms which appear earlier than alopecia, since prognosis is more rewarding with early diagnosis, leading to complete recovery.