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Biomedical subjects

L M Tsai

Publications and source records attributed to L M Tsai.

At least 19 recordsLinked to original sources

Blockade of alpha1-adrenoceptors and cardiac depressant effect by a newly synthetic antihypertensive drug, DL-017 of quinazoline derivative.

The electromechanical effects of 3-[[4-(2-methoxy phenyl)piperazin-1-yl]methyl]-5-(methylthio)-2,3-dihydroimidazo[1,2-c]quinazoline (DL-017), a newly synthesized quinazoline-derived antihypertensive agent, on mammalian cardiac tissues were evaluated. In driven canine Purkinje fibers, DL-017 decreased twitch tension, the maximal rate of upstroke of the action potential (Vmax), and intracellular Na+ activity (a(i)Na) in a concentration-dependent manner. The action potential duration was decreased in canine Purkinje fibers but increased in guinea pig papillary muscles. In guinea pig ventricular papillary muscles, phenylephrine in the presence of 1 microM propranolol increased the twitch tension in a concentration-dependent manner. At 10 microM, phenylephrine significantly decreased a(i)Na and shortened the action potential duration. DL-017 at 0.01 microM inhibited these phenylephrine-induced effects and shifted the concentration-dependent curve to the right. In sinoatrial nodes, DL-017 inhibited pacemaker activity, involving decreases in the slope of diastolic depolarization and Vmax and an increase in a delay of repolarization. These results suggest that, in addition to blockade of alpha1-adrenoceptors and Na+ channels, DL-017 reduces cardiac excitability and contractility in association with inhibition of slow inward Ca2+ and outward K+ channels. Since two order higher concentrations are required, the contribution of DL-017 to cardiac depressant from blockade of ionic channels seems to be less important when this compound is clinically used as an antihypertensive drug.

Action Potentials↗

Emergency medical technicians' disaster training by tabletop exercise.

The objective of this study was to assess the attitudes of emergency medical technicians (EMTs) toward tabletop drills to determine the effect of tabletop simulation on the EMT student perception of disaster preparedness and management. In November 1998 and April 1999, 59 firefighters underwent 260 hours of EMT intermediate level training at the National Cheng Kung University Hospital in Tainan, Taiwan. All participants had experience in field disaster exercise training before they attended this EMT training course. The EMT courses included a disaster and mass-casuality incident program. A 9-item questionnaire was completed by the 59 EMTs before (for field exercise) and after undergoing the tabletop drills. The results of the survey revealed that the field operation exercise could not provide adequate provisions to link the results of disaster exercises to appropriate changes in terms of training, equipment, supplies, and plans. Field operation failed to show the ability of others to fill in during the absence of key officials. Tabletop drilling provided better performance for these 2 issues. Tabletop exercise also provided a better chance than field exercise to evaluate the response without the use of telephones, which are not always reliable in real emergency situation. For disaster exercises, limitations of field operation drills such as communications, coordination, assignment of responsibilities, and postevent mitigation priorities were noted, and tabletop drills provided additional benefits for these settings. Large-scale effect evaluation of different drills may be necessary to design future disaster preparedness programs.

Adult↗

Antihypertensive action and blockade of alpha1-adrenoceptors by DL-017, a quinazoline derivative.

3-[[4-(2-Methoxyphenyl)piperazin-1-yl]methyl]-5-(methylthio)-2,3-dihydroimidazo[1,2-c]quinazoline (DL-017), a quinazoline derivative, exhibits alpha 1 -adrenoceptor antagonistic and type I antiarrhythmic effects on mammalian cardiac tissues. In the current study, the effects of DL-017 on the hemodynamic profile in anesthetized, spontaneously hypertensive rats were evaluated. Intravenous administration of DL-017 induced dose-dependent reductions of heart rate and blood pressure, which persisted over 2 h. DL-017 exerted a maximal antihypertensive effect at 0.1 mg/kg, which was similar to that of 0.1 mg/kg of prazosin. DL-017 was able to block the pressor response to phenylephrine but not to angiotensin II. Regional cerebral blood flow of the right parietal cortex decreased by 14 +/- 4% 10 min after bolus injection and then rapidly returned to control levels while the arterial pressure was still low. These results indicate that blockade of the alpha 1 -adrenoceptor by DL-017 contributes to reduction of arterial pressure. The antihypertensive effect without reflex tachycardia and loss of autoregulation of cerebral blood flow makes DL-017 suitable for chronic long-term treatment of hypertension.

Adrenergic alpha-Agonists↗

Characteristics of repeated ambulance use in an urban emergency medical service system.

BACKGROUND AND PURPOSE: Although many studies have examined the reasons for repeated use of emergency medical service (EMS), little information is available concerning repeated ambulance use in Taiwan. This study evaluated the characteristics of repeated EMS ambulance use in an urban EMS system in Taiwan. METHODS: Data from a local EMS computerized database for the period from January 1996 through December 1998 were collected for analysis. All calls to the dispatch center that resulted in EMS transports were included. Repeat users were identified by matching the user name, sex, age, and home address. Transports were categorized according to how many times the patient was transported by ambulance during the 3-year period: single use, one time; repeated use, two or three times; or frequent use, more than three times. RESULTS: During the 36-month study period, there were 41,792 calls, with 13,076 non-transports (a non-transport rate of 31.3%). Of the 28,716 transports during the study period, 2,101 represented repeated or frequent use (7.3%); the rate of frequent use was 1.4% (406/28,716). The frequency of repeated use reached a daily first peak at 8:00 AM, with the second and third peaks at 1:00 PM and 7:00 PM. The mean age increased with increasing repeated use of transport (37.25 +/- 0.24 vs 41.55 +/- 1.03 vs 46.23 +/- 1.57 years, respectively; p < 0.001). The percentage of non-trauma missions increased with increasing repeated use of transport (26.3% vs 55.6% vs 73.2%; p < 0.001). Response time significantly increased for repeated use (analysis of variance [ANOVA], p < 0.001). The on-scene interval (time from arrival until departure) in the single-use group was shorter than in the repeated and frequent use groups (ANOVA, p < 0.005). CONCLUSIONS: The results of this study indicate that the characteristics of repeat users of EMS transport differ from those of single users. Characteristics of service time, reason for transport, and interval to each subsequent call varied among different groups of users. Studies of repeat use under a wider range of conditions such as in rural EMS systems and after implementation of a priority-dispatch system are needed to determine the implications of repeated ambulance use.

Ambulances↗

Sodium nitroprusside increases pacemaker rhythm of sinoatrial nodes via nitric oxide-cGMP pathway.

Effects of sodium nitroprusside (SNP), a nitric oxide donor, on the action potential in isolated guinea-pig sinoatrial nodes and ventricular papillary muscles were investigated. In the driven ventricular papillary muscle, SNP (10(-10)-10(-3) M) decreased the twitch tension in a concentration-dependent manner without significantly changing the configuration of action potential and the maximal velocity of depolarizing upstroke. In isolated sinoatrial nodes, SNP (10(-8)-10(-3) M) increased the pacemaker rhythm in a concentration-dependent manner. At 10(-5) M SNP, the pacemaker activity increased from 197.2+/-6.1 to 221.4+/-9.7 bpm. Changes of configuration of the action potential included a decrease of the duration of repolarization, i.e., from peak to the maximal diastolic potential (MDP), from 141.4+/-6.4 to 130.0+/-7.0 ms and an increase of the slope of the diastolic membrane potential from 101.6+/-5.3 to 116.5+/-7.3 mV/s (n=6, p<0.05). However, MDP and threshold potential were not significantly changed. Methylene blue (MB, 10(-5) M), a guanylate cyclase inhibitor, significantly decreased the pacemaker activity of the sinoatrial node by increasing the durations of repolarization and diastolic depolarization. After pretreatment with 10(-5) M MB, the effect of SNP was inhibited. The results indicate that nitric oxide, released from SNP, increases the pacemaker activity by enhancing the rates of repolarization and diastolic depolarization. These effects are possibly due to increases in delayed-rectifier K+ and diastolic slow inward currents, which are involved in a mechanism associated with the NO-cGMP pathway.

Action Potentials↗

G-33A mutation in the promoter region of thrombomodulin gene and its association with coronary artery disease and plasma soluble thrombomodulin levels.

Thrombomodulin is an endothelial glycoprotein that decreases thrombin activity and activates protein C. A recent study has shown that G-33A promoter mutation of the thrombomodulin gene occurs particularly in Asians. In this study, we analyzed the distribution of G-33A mutation in the promoter region of the thrombomodulin gene in the Chinese population and determined whether the mutation might be a risk for coronary artery disease (CAD). In addition, the influence of this mutation on plasma soluble thrombomodulin levels in patients with CAD was also examined. We studied 320 consecutive patients (mean age 63 years; 73% men) with CAD and 200 age- and sex-matched control subjects. Screening for thrombomodulin G-33A promoter mutation was conducted using polymerase chain reaction, single-strand conformation polymorphism, and direct deoxyribonucleic acid sequencing. The frequency of the G-33A mutation (GA+AA genotypes) was significantly higher in the CAD group (23.8% vs 15.5%, odds ratio [OR] 1.70, p = 0.031). Multiple logistic regression analysis showed that the mutation was an independent risk factor (OR 1.81, p = 0.016) for CAD, as was hypertension (OR 1.44, p = 0.040), diabetes mellitus (OR 2.50, p <0.001), and smoking (OR 2.15, p <0.001). In CAD patients with GG genotype, the soluble thrombomodulin level increased with the extent of CAD (36 +/- 15 vs 47 +/- 18 vs 55 +/- 36 ng/ml in 1-, 2-, or 3-vessel CAD, p <0.001). However, in CAD patients with G-33A mutation, there was no difference between the levels of soluble thrombomodulin (39 +/- 17 vs 37 +/- 15 vs 42 +/- 18 ng/ml, p = NS) in 1-, 2-, or 3-vessel CAD. Our observations suggest that there is a significant association of the G-33A mutation in thrombomodulin gene with CAD, and this mutation may influence the soluble thrombomodulin levels in patients with CAD.

Asian People↗

Correlation of homocytsteine levels with the extent of coronary atherosclerosis in patients with low cardiovascular risk profiles.

Elevation of homocysteine is now known as an independent risk factor for vascular diseases. However, influences of homocysteine to the extent of coronary atherosclerosis in patients with different coronary risk profiles have not been studied. In this study, we used angiographic "diffuse score" and "clinical vessel score" to evaluate the extent of coronary atherosclerosis, and examined the correlation between levels of serum total homocysteine and angiographic scores among patients with high- and low-risk profiles. Seventy consecutive patients (58 men and 12 women, mean age 50 years) undergoing selective coronary angiography for the first time were recruited for this study. Patients were divided into high-risk (risk factor > or =3, n = 35) and low-risk (risk factor <3, n = 35) groups. Linear regression analysis revealed that levels of serum homocysteine were only significantly correlated with diffuse (r = 0.217, p = 0.007) and clinical vessel (r = 0.078, p = 0.037) scores in low-risk patients. These correlations could not be observed in diffuse (r = 0.070, p = 0.319) and clinical vessel (r = -0.001, p = 0.970) scores in the high-risk group. In conclusion, levels of homocysteine correlated with the extent of coronary atherosclerosis only among patients with low cardiovascular risk profiles.

Coronary Angiography↗

Clinical presentations and prognostic factors of a glyphosate-surfactant herbicide intoxication: a review of 131 cases.

OBJECTIVE: Suicide attempts with agricultural chemicals are common in southern Taiwan. Among them, glyphosate-surfactant herbicide (GlySH) intoxication has been encountered with increasing frequency. Although a number of reports have described the clinical course and outcomes following ingestion, predictors of serious complications and mortality have not been elucidated. The purpose of this study was to define predictors of serious complications and probable mortality. METHODS: This was a retrospective study of 131 GlySH-intoxicated patients treated at the National Cheng Kung University Hospital from 1988 to 1995. Medical charts were reviewed and clinical and laboratory variables were abstracted, looking for predictors of mortality. RESULTS: The most common symptoms included sore throat (79.5%), and nausea with or without vomiting (73.8%). The most common laboratory findings were leukocytosis (68.0%), low serum bicarbonate (48.1%), and acidosis (35.8%). Overall, 11 of 131 patients (8.4%) died; the mean +/- SEM time to death was 2.8 +/- 0.8 days after presentation. When comparing the clinical and laboratory characteristics among the survivor and fatality groups, significant differences were identified. Respiratory distress, pulmonary edema, respiratory distress necessitating intubation, shock (systolic blood pressure less than 90 mm Hg), altered consciousness, abnormal chest x-ray, renal failure necessitating hemodialysis, larger amount of ingestion (>200 mL), and hyperkalemia were predictors highly associated with poor outcomes and mortality. Using multiple logistic regression, three predictors were identified, which may predict mortality in severely intoxicated patients. CONCLUSIONS: In managing patients who have larger amount of GlySH ingestion, airway protection, early detection of pulmonary edema, and prevention of further pulmonary damage and renal damage appear to be of critical importance.

Female↗

Association of follow-up change of left atrial appendage blood flow velocity with spontaneous echo contrast in nonrheumatic atrial fibrillation.

STUDY OBJECTIVES: To evaluate the time-related change of left atrial (LA) appendage flow velocity in chronic atrial fibrillation (AF) by follow-up transesophageal echocardiography (TEE) and to investigate its association with the occurrence of LA spontaneous echo contrast. DESIGN: Prospective follow-up study. SETTING: University-based, tertiary referral medical center. PATIENTS: Forty-seven patients with chronic nonrheumatic AF. INTERVENTIONS: All studied patients underwent both a baseline and follow-up TEE during a mean period of 13 +/- 7 months. MEASUREMENTS AND RESULTS: Baseline TEE revealed that LA spontaneous echo contrast was present in 28 patients (group 1) and was absent in 19 patients (group 2). The LA appendage flow velocity profiles at baseline were significantly lower in group 1 than in group 2; on follow-up, the appendage flow velocities decreased significantly in group 2, but were not significantly changed in group 1. Follow-up TEE revealed that spontaneous echo contrast was persistent in all group 1 patients. In group 2, LA spontaneous echo contrast was newly observed in 9 patients (group 2A) but was persistently absent in 10 patients (group 2B). In group 2A, all of the LA appendage flow velocity profiles decreased significantly at the follow-up study. In group 2B, however, only LA appendage inflow velocity integral showed significant decrease on follow-up; there were no significant changes in LA appendage outflow velocity indexes and peak inflow velocity. CONCLUSIONS: LA appendage flow velocity may decrease with time in some patients with AF, and this change is associated with a new occurrence of LA spontaneous echo contrast. For patients without LA spontaneous echo contrast, serial follow-up of the LA appendage flow velocity profiles may be useful for predicting future development of spontaneous echo contrast. Once LA spontaneous echo contrast occurs in AF patients, it tends to persist with time and the LA appendage is usually under a persistently low flow state.

Adult↗

Effect of atrial fibrillation on pulmonary venous flow patterns assessed by Doppler transesophageal echocardiography.

STUDY OBJECTIVES: To investigate the effect of atrial fibrillation (AF) on pulmonary venous flow (PVF) patterns in a cohort with nonrheumatic AF. DESIGN AND SETTINGS: A prospective and controlled study undertaken at a tertiary referral medical center. PATIENTS AND MEASUREMENTS: The echocardiographic parameters of left superior PVF as assessed by Doppler transesophageal echocardiography in 40 patients with chronic AF (group 1) were compared to those of 33 volunteers with sinus rhythm (group 2) and well-matched baseline characteristics. RESULTS: : All group 1 patients presented with single systolic forward flow (SFF) patterns. In contrast, single and double SFF patterns were found equally in group 2. With regard to reverse flow (RF), most group 1 patients (33 of 40) had an early systolic RF and none had atrial RF; however, most group 2 subjects (29 of 33) had an atrial RF. Some of the group 1 patients (17%) had a late systolic RF in the absence of significant mitral regurgitation. In group 1, the SFF appeared later and disappeared earlier than in group 2. The mean systolic peak velocity and time-velocity integral (TVI) of the SFF were significantly lower in group 1 compared to group 2. The diastolic peak velocity and TVI were not significantly different between groups. CONCLUSIONS: : Our data indicate that AF independently and significantly affects the PVF and leads to characteristic flow patterns different from sinus rhythm. The presence of AF reduces SFF in addition to the absence of atrial RF. These changes in the flow patterns should be taken into account while interpreting the implications of PVF in the presence of AF.

Aged↗

Sick sinus syndrome in a patient with single coronary artery anomaly.

Single coronary artery anomaly is very rare. The reported manifestations include angina pectoris and congestive heart failure. Here we describe a case of single coronary artery anomaly presenting as sick sinus syndrome, which has no literature precedence. A 47-year-old woman had complained of intermittent dizziness for years. A Holter electrocardiogram showed sinus bradycardia and junctional or ventricular rhythm with a maximal ventricular pause of up to 3.2 seconds. Electrophysiologic study revealed prolonged corrected sinus nodal recovery time. Coronary angiography showed that the left anterior descending artery had a long course with a side branch originating from the proximal part and coursing anteriorly to the territory of the proximal portion of the right coronary artery. The sinus node is usually supplied by the sinoatrial branch via the right coronary artery. Aortography showed that the right coronary artery ostium was absent. A permanent pacemaker was implanted and the patient was discharged in good condition. The present case suggests that coronary artery anomaly may lead to compromised blood supply to the sinus node, and hence sick sinus syndrome.

Coronary Vessel Anomalies↗

Decreased left atrial appendage function is an important predictor of elevated left ventricular filling pressure in patients with congestive heart failure.

OBJECTIVE: The aim of this study was to investigate whether left atrial (LA) appendage function, as indicated by LA appendage blood flow velocities and its ejection fraction, could identify elevated left ventricular filling pressure in patients with chronic congestive heart failure. METHODS: Using transesophageal echocardiography, adequate pulsed Doppler LA appendage active emptying and filling velocities could be recorded in 25 consecutive patients (16 men and 9 women, aged 57+/-10 years) with chronic congestive heart failure (symptom duration > or =1 year). LA appendage ejection fraction calculated as (LA appendage maximal area)-(LA appendage minimal area)/(LA appendage maximal area) x 100 was also determined in these patients. Left ventricular end-diastolic pressure was recorded during cardiac catheterization performed within 24 h of echocardiographic study. RESULTS: Left ventricular end-diastolic pressure was 2 to 47 mm Hg. There were close negative correlations of LA appendage emptying velocity (r=-0.508; P<0.01), filling velocity (r=-0.429; P<0.05) and LA appendage ejection fraction (r=-0.523; P<0.005) with left ventricular end-diastolic pressure. LA appendage active emptying velocity <30 cm/s predicted left ventricular end-diastolic pressure >25 mm Hg with a sensitivity of 72.7%, a specificity of 92.9% and a positive and negative predictive value of 88.9 and 81.3%. CONCLUSIONS: The findings suggest that measurement of LA appendage blood flow velocities and contractile function by transesophageal echocardiography can be used to predict elevated left ventricular filling pressure in patients with congestive heart failure.

Atrial Function, Left↗

Prognostic significance of elevated hemostatic markers in patients with acute myocardial infarction.

OBJECTIVES: The purpose of this study was to determine whether the elevated levels of hemostatic markers in the early phase of myocardial infarction may serve as risk factors for subsequent cardiac mortality. BACKGROUND: Increased plasma hemostatic markers were noted in acute myocardial infarction, indicating that the blood coagulation system is highly activated in those patients. However, there are few clinical data concerning the association between the elevated hemostatic markers and survival in patients with myocardial infarction. METHODS: Blood samples were obtained from 64 patients (mean age 67 +/- 11 years; 49 male) with acute myocardial infarction within 12 h after the onset of symptoms and before the initiation of any antithrombotic treatment. We measured plasma concentrations of fibrinopeptide A (FPA), prothrombin fragment 1+2 (F1+2) and thrombin-antithrombin complex (TAT) using the enzyme-linked immunosorbent assay method, and examined the associations between the level of these markers and survival with Cox proportional hazards models. RESULTS: The follow-up time was 27 +/- 17 months, and 19 patients died of cardiac causes during the follow-up. Univariate survival analysis identified Killip class IV (hazard ratio 4.86; 95% confidence interval [CI] 1.55-15.19), left ventricular ejection fraction (hazard ratio 0.94; 95% CI 0.90-0.99), FPA (hazard ratio 1.54; 95% CI 1.13-2.10), F1+2 (hazard ratio 2.03; 95% CI 1.17-3.53) and TAT (hazard ratio 1.88; 95% CI 1.27-2.79) as significant factors associated with cardiac mortality. In multivariate analyses, only FPA level (hazard ratio 1.84; 95% CI 1.03-3.30) and left ventricular ejection fraction (hazard ratio 0.93; 95% CI 0.88-0.98) were independent predictors of cardiac mortality. CONCLUSIONS: Elevated FPA in the early phase of myocardial infarction identifies patients with increased risk for subsequent cardiac death. This association appears to be independent of residual left ventricular function after infarction.

Adult↗

Prognostic value of Doppler-derived mitral deceleration time in postinfarction patients with left ventricular ejection fractions of 35% or more.

Short Doppler-derived mitral deceleration time of early filling has been proved to be an independent predictor of poor prognosis in patients with left ventricular dysfunction. However, the prognostic value of Doppler-derived mitral deceleration time in postinfarction patients without overt left ventricular dysfunction is poorly understood. A total of 27 survivors of acute myocardial infarction with left ventricular ejection fractions of 35% or more, as determined by radionuclide ventriculography, were prospectively studied. Doppler study was performed 5 to 7 days after the index infarction. The patients were divided into two groups. Group A included 10 patients whose mitral deceleration time was 125 msec or less and group B consisted of 17 patients whose mitral deceleration time was 125 msec or more. The two groups were similar in terms of age and gender distribution and there were no statistically significant differences in coronary risk factors, peak creatine kinase concentration, location of infarction, Killip classification, thrombolytic therapy, left ventricular ejection fraction, or medications. After a mean follow-up period of 30 months, the rate of congestive heart failure (New York Heart Association, NYHA, class II or above) was significantly higher in group A (5/10) than in group B (1/17) (p < 0.01). These results suggest that a short mitral deceleration time could be a useful early predictor of the potential development of future congestive heart failure in postinfarction patients with left ventricular ejection fractions of 35% or more.

Blood Flow Velocity↗

Prognostic determinants of infective endocarditis in the 1990s.

The clinical profiles of infective endocarditis (IE) might have changed in recent years, owing to the advent of transesophageal echocardiography, the introduction of new diagnostic criteria, and the increased frequency of intravenous drug abuse. In this retrospective study, we sought to identify factors affecting the in-hospital outcome of IE patients in a single tertiary referral center in the 1990s (1990-1997). Eighty-eight episodes of IE in 80 consecutive patients admitted from January 1990 through June 1997 were evaluated. Clinical variables that were significantly associated with in-hospital mortality in univariate analyses were entered into a multiple logistic regression model. A total of 22 patients (25%) died. Fatal episodes were significantly more likely than non-fatal episodes to involve older patients (> or = 50 years), use of coumadin, short interval between symptom onset and hospitalization (< 15 days), noncardiac shock, and complications of the heart, central nervous system, and kidneys. White blood cell counts and C-reactive protein concentrations were also significantly higher in fatal than in non-fatal episodes of IE. Multivariate analysis showed that in-hospital mortality was associated with noncardiac shock, neurological complications, cardiac complications, and older age (> or = 50 years). Compared with previous reports, our findings suggest that the clinical profiles of IE have undergone some changes in the 1990s. The most important prognostic predictors of in-hospital mortality in patients with IE were noncardiac shock and neurologic complications.

Adolescent↗

Pulmonary artery leiomyosarcoma.

Pulmonary artery leiomyosarcoma is a rare but highly lethal disease, and can be mistaken for pulmonary thromboembolism. We report a case of pulmonary artery leiomyosarcoma managed with surgical resection, chemotherapy, and radiotherapy. A 57-year-old woman was admitted with complaints of aggravated dyspnea. She was initially treated with oxygen therapy and heparinization for a suspected pulmonary embolism. Echocardiography revealed a dilated right atrium and ventricle and severe tricuspid regurgitation, with an estimated systolic right ventricular pressure of 95 mm Hg; a shadow of a mass in the main pulmonary artery was also noted. Right ventriculography revealed a filling defect, and to-and-fro motion of the mass in the main pulmonary artery. The left pulmonary artery was almost totally occluded by the mass. The patient's condition improved dramatically after palliative excision of the mass and patch reconstruction of the outflow tract of the right ventricle with a bicuspid xenograft. Pathologic examination of the mass revealed leiomyosarcoma. Chemotherapy and radiotherapy were subsequently administered and follow-up imaging studies 3 months postoperatively revealed no recurrence of the tumor. The patient remains well, more than 1 year after treatment. This report emphasises that pulmonary artery sarcoma should be considered in the differential diagnosis in cases of suspected pulmonary thromboembolism.

Diagnosis, Differential↗