Myocardial perfusion imaging with technetium-99m sestamibi SPECT in the evaluation of coronary artery disease

Technetium-99m hexakis-2-methoxy-isobutyl-isonitrile (99mTc sestamibi) has been used for myocardial perfusion imaging in the evaluation of coronary artery disease (CAD) since 1990. The experience of its use in an Asian population with and without previous myocardial infarction (MI), diabetes mellitus (DM), hypertension (HPT) and collateral circulation (COL) is reported. One hundred and thirty-nine patients who underwent treadmill exercise testing with 99mTc sestamibi single photon emission computed tomography (SPECT) and coronary angiogram were studied. The overall sensitivity for the detection of CAD was 91.0% and specificity was 64.7%. For patient without previous myocardial infarction, the sensitivity was 83.8% and specificity was 83.3%. Patients with COL had a higher sensitivity while those with HPT had a lower specificity. Sensitivity was higher in patients with multi-vessel disease (MVD) than single vessel disease (SVD). The overall detection for individual artery stenosis was 74.1% with a specificity of 73.1%. Amongst the three major coronary arteries, sensitivity was highest for the right coronary artery and specificity was highest for the left circumflex artery. Specificity was higher in patients without MI or COL. We found that the agreement between 99mTc sestamibi SPECT and coronary angiogram for the extent of CAD was only 52.5%. The concordance rate was higher for patients with MVD than SVD. It is concluded that 99mTc sestamibi SPECT is a sensitive and specific test for the detection of CAD and localization of disease to individual coronary arteries in our patients with some differences in the subgroups. Agreement between coronary angiogram and 99mTc sestamibi for the extent of coronary artery disease was also satisfactory.

Outpatient coronary angiography using 7 French catheters in Singapore

PURPOSE

Out-patient coronary angiogram (OCA) is commonly performed in many centres using 5 or 6 French (F) catheters. Though this small catheter may reduce bleeding complications, manipulatability and adequate vessel visualisation are problems which may increase procedure time. 7 or 8 F catheters have been used in Caucasians. We report our experience with OCA using 7 F catheters in an Asian centre.

METHODS

Sixty-six patients with low procedural risk were consecutively recruited. They were pre-medicated with oral diazepam. Selective coronary angiogram (SCA) and left ventriculogram were performed via the femoral artery. Parenteral heparin was administered after the arterial puncture. After the procedure, haemostasis was secured by at least ten minutes of manual compression. The patients were immobilised for six hours and thereafter encouraged to walk for about an hour. The groin was inspected by a doctor before discharge and reviewed the following day.

RESULTS

The age ranged from 27 to 73 years with a mean of 52.6. There were 48 men and 18 women. Seventeen patients had previous SCA or angioplasty. There was no significant coronary artery disease (CAD) in 26 patients (39.4%). Thirteen patients (19.7%) had minor CAD, 20 (30.3%) had single or double vessel and 7 (10.6%) had triple vessel disease. The mean procedural time was 16.6 +/- 7.3 minutes, ranging from 7 to 54. Seven (10.6%) of the patients had a small haematoma prior to discharge. None of the haematoma deteriorated at review. We did not find sex, age, history of diabetes mellitus or hypertension, height, weight, body mass index, use of anti-platelet agents, systolic blood pressure at and after the procedure and coronary artery anatomy to be associated with an increased risk of haematoma. The estimated cost savings for a non-subsidized patient was S$285 and for a subsidized patient was S$66.

CONCLUSION

We conclude that OCA using 7 F catheters is a safe and efficacious procedure in our patients.

The first example of anti-Gya detected in Hong Kong

The incidence of anti-Gya is known to be extremely rare, and only a few examples have been reported in Japanese persons and in Caucasians. This case history reports the first example of anti-Gya detected in a Chinese person. The propositus is an 83-year-old male patient whose anti-Gya was revealed because of incompatibility of all units of blood tested by a saline indirect antiglobulin test (SIAT). Although the antibody had a titer of 512 by SIAT, 10 units of Gy(a+) red cells were transfused without any adverse effect.

Simultaneous ST-segment elevation in lead V1 and depression in lead V2. A discordant ECG pattern indicating right ventricular infarction

The major electrocardiographic change in right ventricular infarction (RVI) is ST-segment elevation in leads V4R-V6R. The authors describe a discordant electrocardiographic pattern of ST-segment elevation in lead V1 and ST-segment depression in lead V2 in five patients presenting with acute transmural (Q wave) inferior infarction and RVI. There were 51 patients with transmural inferior infarction from a thrombolytic trial. In 25 patients, the ST-segment in the right-sided precordial leads was elevated by > or = 1 mm indicating the presence of RVI. In 5 of these 25 patients, simultaneous ST-segment elevation of 1.0-8.0 mm (mean, 2.8 +/- 2.9 mm) in lead V1 and ST-segment depression of 2.5 to 4.0 mm (mean, 3.3 +/- 0.6 mm) in lead V2 were also present. The discordant pattern of the ST-segments in leads V1 and V2 is an important and specific sign for RVI.

A survey of the incidence of Miltenberger antibodies among Hong Kong Chinese blood donors

BACKGROUND

The ready availability of red cells of the Miltenberger (Mi) class III phenotype (6.28%) prompted the study of Mi antibodies among Chinese blood donors in Hong Kong, 98 percent of whom are descended from inhabitants of Guangdong Province in southern China.

STUDY DESIGN AND METHODS

Red cells of the Mi class III phenotype were used to conduct a survey of the frequency of Miltenberger antibodies in 56,161 random Chinese blood donors, over a period of 12 months, using a microplate technique.

RESULTS

Sera from 32 donors (0.057%) were found to contain Mi antibodies: sera from 22 contained anti-Mur + Hut; sera from 4 contained anti-Vw + Mur + Hut; sera from 4 had monospecific anti-Mur; and sera from 2 had monospecific anti-Hil. The immunoglobulin isotypes of 24 sera were mixtures of IgM and IgG, 4 were pure IgM, and 4 were pure IgG.

CONCLUSION

The majority of Mi antibodies detected were naturally occurring. This survey proved useful for mass screening of random donors for the procurement of valuable Mi antisera.

Risk factors for acute myocardial infarction in a southern Chinese population

Although the mortality rate from coronary artery disease in Hong Kong is only one-fourth of that of northern Europe and the United States, the disease has been and remains the second major cause of death (after all cancers combined). Beginning in 1987, we have conducted a case-control study of acute myocardial infarction in four Hong Kong hospitals. This study, one of the biggest case-control studies conducted in the Chinese population of both men and women, confirms the importance of several risk factors--cigarette smoking, history of hypertension, history of diabetes, body fatness, and lack of physical activity--previously described in data collected in western populations. In addition, more adverse childhood experience was also found to be an important risk factor of acute myocardial infarction. Further research in appropriate intervention measures in education in the prevention and cessation of smoking, the control of blood pressure, diabetes, and overweight, and adequate exercise could significantly help reduce the risk of acute myocardial infarction in the Hong Kong Chinese population.

Fasting blood sugar level: a determinant for in-hospital outcome in patients with first myocardial infarction and without glucose intolerance

The body responds to stress, e.g. during infections or acute illnesses, by a variety of neurohormonal mechanisms. Some of these physiological responses sometimes lead to an elevation of the blood sugar level (BSL). BSL is a biochemical parameter which is readily and rapidly assayed. The aim of our study was to determine whether the glycaemic state of patients with their first myocardial infarction and without previous glucose intolerance was of predictive value for the type of outcome during the in-hospital and post-hospitalisation periods. We also delineated the factors which determined subsequent glucose tolerance in this group of patients. Forty-four consecutive patients were studied and those with complicated in-hospital outcome had a significantly higher mean BSL at admission (ABSL) and fasting BSL (FBSL). FBSL was shown to be a predictor for in-hospital outcome. The odds ratio for a complicated in-hospital outcome was 3.3 times for patients with a FBSL of greater than 6.7 mmol/l (120 mg/dl) than those without (p = 0.0175). We could not identify a predictor for an adverse outcome in the post-hospitalisation period. Oral glucose tolerance test was performed on twenty-seven patients at least six weeks after the infarction. Twelve were normal and fifteen were abnormal (six were diabetic and nine had impaired glucose tolerance). The odds ratio for patients with glycosylated haemoglobin level (HbAlc) between 7.5 and 9.5% was 2.19 higher than those less than 7.5% (p = 0.049). In conclusion, the FBSL is a determinant for the outcome for these patients during the in-hospital and not the post-hospitalisation period.(ABSTRACT TRUNCATED AT 250 WORDS)

Rh phenotypes of Chinese blood donors in Hong Kong, with special reference to weak D antigens

Among Hong Kong Chinese blood donors, 99.71 percent were found to be D+. Of these, 55.02 percent were of the phenotype CCDee. The Du phenotype was found to be present in 0.016 percent. Among the 0.27 percent who were apparently D-, 0.079 percent were of the Del phenotype, while the remaining 0.19 percent were "true D-," as defined by a nonreactive eluate obtained by an adsorption and elution procedure using anti-D. The ccdee phenotype constitutes 56.77 percent of the "apparent D-" and 80.24 percent of the true D-. Data show that anti-D rarely occurs in Hong Kong Chinese, and it is postulated that this could be due to the presence of a very weak form of the D antigen among many of those who appear to be D-.

An unusual cause for cyanosis

Cyanosis is a common physical sign in clinical medicine. Cardiac or respiratory conditions are the usual causes. We report a patient with an unusual cause for cyanosis and highlight the salient clues that lead to the diagnosis.

The effect of oral midazolam and diazepam on respiration in normal subjects

Benzodiazepine have been shown to suppress ventilatory responses to hyperoxic hypercapnia (HCVR) and isocapnic HVR when taken parenterally. Most patients would, however, prefer to take an oral rather than parenteral preparation but the effect of oral benzodiazepine on these ventilatory responses has not been well studied. We therefore studied the effect of oral midazolam (7.5 mg) and diazepam (5 mg) both given orally on resting ventilation and respiratory drive, as assessed by HCVR and HVR. Flumazenil, a specific benzodiazepine antagonist, was administered intravenously to reverse the effect. A mental alertness-drowsiness index in five grades, from 1 (awake and alert) to 5 (asleep), was used to assess the sedation effect. Six normal male subjects, (aged 31 +/- 1.6 yrs) (mean +/- SD), participated in the study. Mean resting ventilation, and ventilatory response to HCVR and HVR were not significantly altered by these drugs when taken orally. Flumazenil also had not significant effect on HCVR and HVR. However the mental alertness-drowsiness index rose from 1 to 2.83 with oral midazolam and reversed to 1.25 with flumazenil. Similarly, this index increased from 1 to 2.25 after oral diazepam and reversed to 1.42 after flumazenil. In conclusion, we found that even though oral midazolam and diazepam produced a significant sedation effect, which was reversed with flumazenil, the drugs had no effect on ventilation at rest and the ventilatory responses to hypoxia and hypercapnia.

The effect of oral midazolam and diazepam on respiration in normal subjects

Benzodiazepine have been shown to suppress ventilatory responses to hyperoxic hypercapnia (HCVR) and isocapnic HVR when taken parenterally. Most patients would, however, prefer to take an oral rather than parenteral preparation but the effect of oral benzodiazepine on these ventilatory responses has not been well studied. We therefore studied the effect of oral midazolam (7.5 mg) and diazepam (5 mg) both given orally on resting ventilation and respiratory drive, as assessed by HCVR and HVR. Flumazenil, a specific benzodiazepine antagonist, was administered intravenously to reverse the effect. A mental alertness-drowsiness index in five grades, from 1 (awake and alert) to 5 (asleep), was used to assess the sedation effect. Six normal male subjects, (aged 31 +/- 1.6 yrs) (mean +/- SD), participated in the study. Mean resting ventilation, and ventilatory response to HCVR and HVR were not significantly altered by these drugs when taken orally. Flumazenil also had not significant effect on HCVR and HVR. However the mental alertness-drowsiness index rose from 1 to 2.83 with oral midazolam and reversed to 1.25 with flumazenil. Similarly, this index increased from 1 to 2.25 after oral diazepam and reversed to 1.42 after flumazenil. In conclusion, we found that even though oral midazolam and diazepam produced a significant sedation effect, which was reversed with flumazenil, the drugs had no effect on ventilation at rest and the ventilatory responses to hypoxia and hypercapnia.

Bv: a distinct category of B sub-group among Chinese blood donors in Hong Kong

During the period 1984-1989, a total of 46 examples of Bv phenotype were encountered out of a total of 567,210 donors, giving an incidence of 1 in 12,330 among the Chinese in Hong Kong. The Bv determinant corresponds to the portion of the B antigen that is present on rabbit red cells, and gives a negative reaction with polyclonal anti-B reagents absorbed with rabbit red cells that still react with B3. Some potent monoclonal anti-B reagents confirm the absence of a B epitope from Bv red cells even by adsorption and elution techniques. The failure of some monoclonal anti-B reagents to detect Bv demonstrates the need to select or blend monoclonal anti-B reagents for use in typing Oriental bloods. Cell-conversion techniques failed to convert O cells to B cells using Bv serum with the appropriate substrate, whereas sera from most of the other B variants were capable of doing so. The Bv phenotype, therefore, represents a distinct category of B subgroups that is easily distinguishable from B3 and other B variants.

Silent myocardial ischaemia: the Tan Tock Seng experience

The results of treadmill exercise stress test (TMX) for ischaemia is based on ST-segment depression. Patients with positive test may or may not be symptomatic. This study examines if there are any differences between these two groups of patients. A total of thirty-nine patients with coronary artery disease and positive TMX results in 1988 was studied. There were 16 patients with chest pain and 23 without. They were followed-up for a mean period of 16.9 and 15.2 months respectively. The following factors were found not to be statistically significant between these two groups of patients: age, sex, race, height, weight, history of hypertension, diabetes mellitus or smoking, indication for the test, use of drugs, total and HDL-cholesterol, exercise duration and the initial double product. The difference between the maximal double product of the two groups was statistically significant (p = 0.004). In the follow-up period, in the group of patients with silent myocardial ischaemia, one had a cardiac event and one underwent revascularisation. While in the symptomatic group, two had cardiac events and seven underwent revascularisation. There were no deaths in either group. The difference in overall outcome was significant statistically (p = 0.002). Therefore, patients with silent myocardial ischaemia have a higher maximal double product in TMX; hence a higher maximal workload and a less adverse outcome compared to symptomatic patients.

The MiIII phenotype among Chinese donors in Hong Kong: immunochemical and serological studies

The incidence of the MiIII phenotype among Chinese blood donors in Hong Kong was found to be 6.28%. Eleven individuals apparently homozygous for the MiIII gene were detected by immunoblotting with monoclonal antibodies R1.3 and R18. R1.3 detects an identical epitope on both glycophorins A and B and R18 detects a different epitope on glycophorin A. Immunoblotting with R1.3 showed an absence of bands corresponding to normal glycophorin B. Immunoblotting with R18 showed an absence of a 58 K band, which corresponds to a heterodimer of normal glycophorin B complexing with the MiIII component, found in MiIII heterozygotes. In two families with apparent MiIII homozygous individuals, both parents of the propositi had the MiIII phenotype which implies normal autosomal inheritance of the MiIII gene. In another family, only one parent had the MiIII phenotype and the presence of an Su gene is postulated to explain the immunochemical and serological findings.

Myocardial and skeletal muscle injuries following adenine arabinoside therapy

A healthy young male with chronic persistent hepatitis associated with positive HBsAg and HBeAg and without any predisposing factors for coronary artery disease was treated with a course of prednisolone and adenine arabinoside. At the end of therapy, he developed myocardial and skeletal muscle injuries. The temporal relationship between the administration of the drug and the monophasic nature of the myotoxic injuries strongly suggests that adenine arabinoside induced the clinical manifestations in the patient.

Focal seizure in non-ketotic hyperglycaemia

Structural brain lesions are the common causes of focal seizure. We report two patients who presented with focal fits with non-ketotic hyperglycaemia. There were no focal brain lesions to account for the fits. The fit of one patient was aborted by intravenous phenytoin while the other by controlling the blood sugar.

Anaemia in National Service Registrants in Singapore

This study describes the occurrence of anaemia (haemoglobin level below 12.5 g/dl) amongst National Service (NS) Registrants in Singapore. A total of 32,320 subjects were screened and the prevalence of anaemia was 0.51%. The Indians had the highest prevalence compared to the other races. The commonest cause of anaemia was haemoglobinopathy. Though alpha-thalassaemia is the commonest form of haemoglobinopathy in Singapore, we found that beta-thalassaemia was the commonest form of haemoglobinopathy in anaemic subjects. In the Chinese and Malay races, the commonest cause of anaemia was haemoglobinopathy. For the Indian and Other races, it was iron deficiency. Of all the subjects with haemoglobinopathy, 86.2% did not have a family history of anaemia. Iron deficiency occurred in about a third of the anaemic subjects. The prevalence was highest in the low income groups and the Indian and Other races. But with higher standards of living, blood loss may be a more important cause for iron deficiency than poor nutrition.

Ankle fracture treated with the AO principle--an experience with 116 cases

One hundred and sixteen cases of ankle fractures were classified by the AO system and treated by open reduction and internal fixation in accordance with the AO principles. The stabilization of the lateral malleolus was emphasized. Ninety-six cases were available for functional assessment with an average follow-up of 39 months. The results were good or excellent in 90 per cent of type A fractures and in 70-80 per cent of type B and C fractures. There was no death or non-union. Local complications included wound infection (8.6 per cent) and skin necrosis (3 per cent). This study illustrates the importance of exact anatomical reduction and stable internal fixation to allow early movement after an intra-articular fracture of the ankle.