Value of troponin-T rapid assay, cardiac enzymes, electrocardiogram and history of chest pain in the initial diagnosis of myocardial infarction in the emergency department

We conducted a prospective study of 152 adult patients presenting to an emergency department with chest pain or symptoms suggestive of acute myocardial infarction (AMI) to evaluate the first electrocardiogram (ECG), creatine kinase (CK)-MB and Troponin-T Rapid Assay (TnT) alone or in combination with chest pain in the initial diagnosis of AMI. A provisional diagnosis was made after the history, physical examination and the first ECG reading. Blood specimens were taken for TnT, CK and CK-MB mass. A final discharge diagnosis of AMI was made according to World Health Organization criteria. Seventy-six (50%) of patients had a final diagnosis of AMI. The sensitivities of the first ECG, first CK-MB mass and first TnT were 76.3% (95% confidence interval (CI), 66.8-85.9), 38.2% (95% CI, 27.2-49.1) and 31.6% (95% CI, 21.2-42.0) respectively. The area under the curve for a combination of ECG, CK-MB mass, TnT and chest pain was the highest at 0.937 when compared with chest pain with varying combinations of tests. A combination of the first ECG, CK-MB mass and TnT had a negative predictive value (NPV) of 87.9% (95% CI, 80.0-95.8). The first ECG was the most sensitive test while the combination of chest pain, ECG, cardiac enzymes and TnT gave the best results in the initial diagnosis of AMI. If the first ECG, CK-MB mass and TnT are all negative, the probability of having an AMI is 12%.

Mechanism of reduced GFR in rabbits with ischemic acute renal failure

A reduction in glomerular filtration rate (GFR) is a primary characteristic of ischemic acute renal failure. The present study was undertaken to examine the roles of angiotensin II, tubuloglomerular-feedback (TGF) mechanism, and tubular obstruction for the GFR reduction in the post-ischemic kidney. Renal ischemia was induced by occlusion of the bilateral renal arteries for 60 min, and renal function was examined at 2 and 24 h after the onset of reflow. After the end of 2-h reflow, the GFR was not significantly changed, but the urine flow increased significantly. On the other hand, at the end of 24-h reflow, the GFR and urine flow decreased markedly along with increased filtration fraction. The renal blood flow significantly decreased at 24 h, but not 2 h, after reflow, which was accompanied by increased total renal vascular resistance. Furosemide infusion (1 mg/min/kg) after 24 h of reflow prevented the reduction in GFR and filtration fraction without no changes in renal blood flow and total renal vascular resistance. Pretreatment of enalapril and losartan did not prevent the reduction in GFR, indicating that angiotensin II was not involved. In morphological examinations, tubular obstruction was seen in the proximal and distal tubules of kidneys both at 2 and 24 h after the onset of reflow. In two rabbits subjected to 48 h of reflow, the tubular obstruction was not observed, despite GFR remained depressed. These results suggest that the late reduction in GFR in postischemic kidneys is not mediated by angiotensin II, but is mediated, at least in part, by the TGF mechanism. The tubular obstruction may be not prerequisite for the GFR reduction in rabbits.

The use of abciximab in coronary angioplasty--an Asian centre's experience

BACKGROUND

Abciximab, a monoclonal antibody to platelet glycoprotein IIb/IIIa receptor, has been shown to be effective in reducing ischemic complications after coronary angioplasty in recent trials. However, little is known about its efficacy and safety when used in Asian patients.

METHODOLOGY

Based on our abciximab registry, we performed a retrospective analysis of 115 Asian patients who received the antiplatelet agent while undergoing percutaneous coronary intervention in our centre. They constituted 18.4% of the total number of patients undergoing percutaneous revascularisation during the corresponding period. The majority of the patients were males (84%). The mean age of the cohort was 54 and the mean weight was 70 kg. The ethnic composition of the study population was: Chinese 54%, Indians 21%, Malays 19% and Others 6%. All patients received aspirin 100 mg and weight-adjusted heparin before the procedure. Abciximab may be administered on a preplanned basis prior to the procedure or be given as a 'bailout' strategy.

RESULTS

There was a high clinical success rate of 95.8% and low incidence of ischemic complications when abciximab was given during coronary angioplasty. There were 0% Q myocardial infarction, 3.3% non-Q myocardial infarction and 0.8% death in our series. Bleeding complications were uncommon at 7.6%, predominantly involving the groin and gingiva. Thrombocytopenia occurred in 5.8% of patients. Abciximab was noted to increase the procedural activated clotting time (ACT) by 38 seconds when given concomitantly with heparin. The mean maximal procedural ACT achieved was 323 +/- 51 seconds.

CONCLUSIONS

Abciximab may be used safely and efficaciously in Asian patients undergoing coronary angioplasty. The drug confers protection against ischemic complications during the procedure whether it is administered electively or as a 'bailout'. There is however, a need to redefine the heparin regime for our patients, given the high ACT obtained when abciximab is administered.

Hybrid cardiac revascularisation surgery

Currently, 3 methods of myocardial revascularisation are available for the treatment of coronary artery disease: i) coronary artery bypass grafting (CABG); ii) percutaneous transluminal coronary angiography (PTCA), and iii) transmyocardial laser revascularisation (TMR). Until recently, these procedures were performed exclusive to one another. We report 2 cases of minimally invasive direct coronary artery bypass grafting with subsequent PTCA, and 1 case of staged PTCA followed by TMR performed at our institution. We discuss the role of hybrid procedures in the current era of treatment of ischaemic heart disease.

Ruptured giant intrathoracic lipoblastoma in a 4-month-old infant: CT and MR findings

BACKGROUND

We describe a 4-month-old infant with a ruptured intrathoracic lipoblastoma arising from the parietal pleura and associated with a pleural effusion.

OBJECTIVE

The clinical presentation was rapidly evolving respiratory distress. The chest radiograph showed a large mass and a pleural effusion in the right thoracic cavity. CT demonstrated an inhomogeneous low-attenuation mass which was 7 cm in diameter and which showed areas of enhancement after intravenous contrast medium. MRI showed a fatty intrathoracic mass with intratumoral streaks and whorls, which were attributed to loose fibrovascular connective tissue on pathological examination.

RESULTS

Thoracotomy and pathological examination revealed a ruptured intrathoracic lipoblastoma arising from the parietal pleura.

CONCLUSION

The pleural effusion might have suggested rupture of the tumour.

Right and left bundle branch block in acute inferior myocardial infarction

An 88-year-old man presented with acute Q wave inferior, posterior and right ventricular myocardial infarction which was associated with intermittent complete right and left bundle branch block.

Muscle activation during the tennis volley

PURPOSE

To broaden our understanding of muscle function during the tennis volley under different ball placement and speed conditions by examining the activity of selected superficial muscles of the stroking arm and shoulder (flexor carpi radialis, extensor carpi radialis, triceps brachii, deltoids, and pectoralis major) and muscles related to postural support (left and right external oblique, lumbar erector spinae, and gastrocnemius) during the volley.

METHODS

Seven skilled tennis players were asked to perform volley strokes under 18 experimental conditions, including variations in lateral contact location (forehand and backhand), ball contact height (high, middle, and low), and ball speed (fast, medium, and slow). A ball machine was modified so that the subjects could not predict the ball trajectory before it was released from the machine. Muscle activity was determined using surface electromyographic (EMG) techniques, and the critical instants of a volley were determined using two force platforms and two high-speed (120 Hz) video cameras. Average EMG values for different phases of the volley, defined by the critical instants, were computed.

RESULTS AND CONCLUSIONS

In general, muscle activity increased with increasing ball speed. The extensor carpi radialis was more active than the flexor carpi radialis during both forehand and backhand volleys, suggesting the importance of wrist extension/abduction and grip strength. The increase in EMG levels in the forearm muscles shortly before the ball impact indicated that the subjects did not tighten their grip and wrist until moments before ball impact. Both antero-middle and postero-middle deltoids were active in most stroke phases. However, the roles of the deltoid muscles during a volley cannot be determined without knowing the actions of the other shoulder joint muscles.

Movement characteristics of the tennis volley

PURPOSE

The purpose of this study was to examine selected movement characteristics of the tennis volley by evaluating temporal and ground reaction force (GRF) parameters.

METHODS

Seven skilled tennis players performed volley strokes under 18 experimental conditions including variations in lateral contact location (forehand (FH) and backhand (BH)), ball contact height (high, middle, low), and ball speed (fast, medium, slow). A ball machine was modified so that the subjects could not predict the ball trajectory before it was released from the machine. The GRF and temporal parameters were determined using two force platforms and two high-speed (120 Hz) video cameras, respectively. Average and maximum values of each measured parameter were computed for different phases of the volley.

RESULTS

The average reaction times (from ball release to initial racquet movement (IRM)) for FH and BH trials were 226 and 205 ms, respectively, and the difference was statistically significant. The average stroke time (from IRM to ball impact) ranged from 381 ms in fast speed trials to 803 ms in slow speed trials. A distinct racquet forward motion immediately before ball impact occurred in 75% of the trials and they were evenly distributed between FH and BH trials. An ipsilateral side step (a side step of the foot on the same side of the oncoming ball before the crossover step of the other foot) occurred more often in FH (45%) than in BH (34%) trials.

CONCLUSIONS

The GRF during the stroke phase suggest that the subjects initiated lateral movement by leaning sideward when ball velocity was low and by a vigorous pushoff of the contralateral foot when ball velocity was high.

Minimally invasive direct coronary artery bypass

BACKGROUND

Minimally invasive cardiac surgery is a new and promising approach to the treatment of coronary artery disease allowing surgery to be performed through smaller incisions with lesser morbidity.

METHODOLOGY

From November 1995 to February 1997, ten minimally invasive direct coronary artery bypass (MIDCAB) grafts were performed. The left internal mammary artery was used to bypass the left anterior descending coronary artery (LAD) through a limited left anterior thoracotomy.

PATIENTS

There were seven males and three females and their ages ranged from 42 to 72 years (mean = 60 years). Two patients had prior interventional procedures. Cardiopulmonary bypass was used in the first two patients. Two patients were converted to conventional surgery early in the series.

RESULTS

There was no mortality nor major morbidity. Mean post-operative hospital stay was seven days. To date, three patients have had post-operative angiography confirming the patency of the left internal mammary artery to LAD anastomosis.

CONCLUSION

Early results of the MIDCAB procedure are encouraging. However, the definitive place of such procedures awaits longer term follow-up.

Co-existing left atrial thrombus and myxoma in mitral stenosis--a diagnostic challenge

We report an unusual case of an adult who underwent a mitral valve replacement with concomitant excision of the left atrial myxoma and thrombus. Echocardiography showed the presence of a large "thrombus" within the left atrial appendage, body and atrial septum. There was difficulty in trying to distinguish between the atrial thrombus and myxoma due to their morphological similarities. At time of surgery, frozen section confirmed the atrial septal component of the thrombus to be an atrial myxoma and the atrial septum was excised to obtain a clear margin.

Left bundle branch block and increased transverse:frontal plane QRS voltage ratio in severe left ventricular dysfunction

Six patients with complete left bundle branch block and an increase in the transverse:frontal plane QRS voltage ratio are described. All these patients presented with congestive heart failure which was due to severe left ventricular dysfunction.

Midodrine for the treatment of intradialytic hypotension

Recurrent intradialytic hypotension is probably the most severely disabling feature in dialysis patients and the etiology is multifactorial. We assessed the efficacy and safety of midodrine, a selective alpha1-adrenergic pressor agent in 12 patients with recurrent intradialytic hypotension. Symptomatic intradialytic hypotension was defined as hypotensive symptoms occurring with a systolic blood pressure < 100 mm Hg or with 25% decrease in systolic blood pressure in those patients with a basal systolic blood pressure of 100 mm Hg. The patients who suffered from symptomatic intradialytic hypotension and failed to improve after cautious body weight adjustment were included into the study. The lowest intradialytic and postdialysis blood pressures were monitored for 18 consecutive dialysis sessions before and after midodrine treatment. Clinical signs and symptoms were also recorded during both periods. With midodrine, the mean (+/- SE) lowest systolic and diastolic blood pressure increased significantly from 68.7 +/- 3.1 and 42.8 +/- 2.0 mm Hg to 84.7 +/- 3.9 and 52.7 +/- 2.7 mm Hg respectively during the study (p < 0.01). Midodrine treatment also significantly increased postdialysis systolic and diastolic blood pressures from baseline values of 90.8 +/- 3.8 and 58.3 +/- 3.0 mm Hg to 113.3 +/- 7.1 and 70.6 +/- 3.1 mm Hg (p < 0.01 and p < 0.01 respectively). In addition, oral administration of midodrine also significantly decreased the total volume of intravenous fluid administered during symptomatic hypotension. The clinical signs and symptoms during dialysis were improved in all patients. There were no differences in hemoglobin, serum albumin, urea, creatinine, fasting blood sugar or volume removed per dialysis between both periods of the study. In conclusion, our study has demonstrated that midodrine is a safe and effective treatment for the prevention of recurrent intradialytic hypotension if routinely premedicated before each dialysis session.

A case of unusual electrocardiographic presentation of right ventricular myocardial infarction

This is a case of an unusual electrocardiographic manifestation of a patient with right ventricular (RV) myocardial infarction occurring in association with left ventricular inferoposterior myocardial infarction. There was massive ST-segment elevation in the precordial leads resembling that of an anterior myocardial infarct in addition to the ST-segment elevation seen normally in right ventricular leads. Two-dimensional echocardiography confirmed right ventricular hypokinesia and coronary angiography revealed single-vessel coronary artery disease involving the right coronary artery. It served to remind us that the presence of diffuse and massive ST-segment elevation in the precordial leads in a patient with inferior myocardial infarction may indicate simultaneous RV infarction and warrants further confirmatory tests.

Right sided chest lead electrocardiographic abnormalities in acute pulmonary embolism

Twelve lead electrocardiograms together with right-sided chest leads V4R, V5R and V6R were recorded in four patients with acute pulmonary embolism. All four patients showed ST segment elevation and a qs or qr pattern (with prominent q waves) in one to three of the leads V4R, V5R and V6R. These abnormalities were absent in the repeat electrocardiograms which were recorded after the acute illness.

Myocardial infarction in patients aged 40 years and below: an angiographic review

Over a period of 27 months, 32 patients aged 40 and below were admitted for acute myocardial infarction. Twenty-nine had coronary angiography with a mean of 15.7 +/- 10.0 days following infarction. Fourteen patients had single vessel, 10 multi-vessel and 5 had only minor coronary disease. Disease in the left anterior descending (LAD) artery was more common than in the circumflex or right coronary artery (RCA), but myocardial infarction occurred with near equal frequency in both the LAD and RCA territories. Only 2 infarct-related vessels were collateralized. Spontaneous coronary dissection was detected in 2 patients. The left ventricular function was significantly impaired in about half of the patients.

Independent regulation of matrix metalloproteinases and plasminogen activators in human fibrosarcoma cells

Serine proteases and matrix metalloproteinases have been shown to often cooperate in multiple physiological and pathological processes associated with changes in the extracellular matrix (ECM). We have examined the interaction between the plasminogen activator (PA)-plasmin system and matrix metalloproteinases (MMPs) in HT1080 human fibrosarcoma cells treated with 12-O-tetradecanoyl-phorbol-13-acetate (TPA). While TPA treatment evoked a temporary increased expression of urokinase type PA (uPA), the production of both types of human plasminogen activator inhibitors (PAI) was induced and sustained over 12 h by TPA treatment shifting the protease-protease inhibitors balance in favor of the inhibitors. TPA treatment of HT1080 cells induced the expression of interstitial collagenase (MMP-1) and increased the expression of gelatinase B (MMP-9), tissue inhibitor of metalloproteinases-1 (TIMP-1), and MT-MMP, a membrane-bound activator of progelatinase A (proMMP-2), while MMP-2 and TIMP-2 expression were decreased. Increased MT-MMP expression by TPA treatment was associated with increased activation of proMMP-2. These data show that the regulation of PA-plasmin and metalloproteinase and their specific inhibitors is uncoordinated. In addition, inhibition of the PA-plasmin system by PAI-2 or aprotinin did not prevent the activation of proMMP-2 by TPA, suggesting that plasmin is not involved in MT-MMP-mediated activation of proMMP-2.

Premature myocardial infarction in Singapore--risk factor analysis and clinical features

A retrospective analysis was carried out on all patients aged 40 years and below with acute myocardial infarction admitted to the coronary care unit (CCU) at the National University Hospital (NUH). We found that most came early direct to hospital, more than half of those eligible received thrombolysis and there was a low incidence of complications. Compared to the Singapore population, Indians in the group were over-represented. The most common coronary risk factor was smoking. A majority had elevated serum cholesterol level. These observations may provide some insight for the primary prevention of premature coronary artery disease in young people in Singapore.

Severe aortic regurgitation due to Neisseria mucosa endocarditis

A rare occurrence of Neisseria mucosa endocarditis on a native aortic valve not known to be diseased is reported. Despite vigorous antibiotic therapy, severe aortic regurgitation developed necessitating aortic valve replacement. At operation, the right coronary cusp was retracted with two small nodules attached to its edge and the non-coronary cusp was perforated. Neisseria mucosa endocarditis is very rare, and involves abnormal mitral or prosthetic valves predominantly. Infection of a native aortic valve, with no known history of disease, is exceptional.

Analysis methods to improve the diagnostic power of treadmill exercise stress testing in patients with suspected angina pectoris

To assess the ability of 3 established analysis methods in exercise stress electrocardiography to non-invasively detect the presence of coronary artery disease (CAD), 67 consecutive patients who had typical angina, positive exercise stress electrocardiography (ST segment depression > or = 1 mm) and coronary arteriography were studied. Thirty-three patients had significant CAD, and 34 had normal coronary arteriograms. The results showed that the Treadmill Score Method, utilising both ST and non-ST segment variables, had the highest accuracy in predicting disease. The predictive power of all 3 methods was lower in females.

Diagnosis of pelvic endometriosis: fat-suppressed T1-weighted vs conventional MR images

OBJECTIVE

The purpose of this study was to compare fat-suppressed T1-weighted with conventional MR images for the diagnosis of endometriosis, focusing on the detectability of peritoneal implants, and to evaluate the usefulness of MR imaging in predicting the severity of disease.

SUBJECTS AND METHODS

We analyzed the MR images of 31 patients with clinically suspected endometriosis. Laparoscopy confirmed no evidence of disease in two and endometriosis in 29. Conventional T1- and T2-weighted images and supplementary axial fat-suppressed images were obtained in all patients. In both groups, detection of endometriotic lesions with MR imaging was compared with detection at laparoscopy. Only the findings on fat-suppressed images were used to evaluate the usefulness of MR imaging in predicting the severity of disease. Early stages of disease included stages I and II; advanced stages of disease included stages III and IV.

RESULTS

Diagnostic accuracy was higher with fat-suppressed imaging (77%) than with conventional imaging (55%) (p = .06). The overall sensitivity in detecting peritoneal implants was significantly higher with fat-suppressed imaging (61%) than with conventional imaging (27%) (p < .01). The disease was likely to be at an early stage when MR images showed peritoneal implants that were 5 mm or less in maximum diameter. The disease was likely to be at an advanced stage when MR images showed an endometrial cyst that was larger than 1.5 cm.

CONCLUSION

Our results show that fat-suppressed MR imaging is more accurate in the diagnosis of pelvic endometriosis and is better for predicting the severity of disease than conventional MR imaging is.

Effects of some non-steroidal anti-inflammatory drugs (NSAIDS) on steroidogenesis in rat and porcine testis

Using the rapid gas chromatographic steroid profiling technique, a number of metabolites of pregnenolone have been separated and quantified after incubation of this steroid with adult rat and neonatal porcine testicular homogenates. It was shown that the 5-ene-3 beta-hydroxy- and the 4-en-3-oxosteroid pathways for androgen biosynthesis were operating in both species, although the former pathway appeared to be more important in porcine testis. This tissue was characterised by the formation of several odorous, and pheromonal, 16-androstenes, which were quantitatively more important than the androgens. Three non-steroidal anti-inflammatory drugs (NSAIDS) caused dose-related inhibition of androgen and 16-androstene biosynthesis when co-incubated with pregnenolone. The order of potency was flurbiprofen > indomethacin > > > aspirin. The possibility that the NSAIDS may interfere with cytochrome P-450 is discussed, since several steroid-transforming enzymes, known to be dependent on this cytochrome for their activity, were markedly inhibited.