The use of SPECT to evaluate growth cessation of the mandible in unilateral condylar hyperplasia.

In unilateral condylar hyperplasia, for surgical intervention to be effective, the status of condylar bone growth has to be assessed correctly. Previously this assessment relied on serial clinical observations. This study aimed to evaluate the MDP-SPECT method of assessing condylar growth in unilateral condylar hyperplasia. Twenty-six MDP-SPECT of the mandible had been performed; 21 were diagnosed as condylar hyperplasia and five as non-mandibular disease. Three isotope parameters: isotope counts, pixel counts and counts per pixel were summed for each condyle per subject. The percentage difference in isotope uptake of the three parameters between the two condyles was calculated as the ratio of the combined counts of the two sides. These differences significantly correlated with each other (Pearson r=0.78-0.98) and with the clinical status of bone growth (Spearman rho=0.72-0.86). There was a significant difference for the count per pixel between the 'growing' condyle (transaxial, T: 15.05+/-7.14, coronal, C: 12.29+/-7.88), the 'no further growth' condyle (T: 5.22+/-4.08, C: 5.67+/-3.88) and the 'normal' condyle (T: 0.82+/-0.76, C: 1.34+/-0.66). This method was able to separate 'active growth' from 'growth cessation' of the condyle by a single MDP-SPECT of the mandible. However, further studies are needed to confirm this finding.

An estimation of deviation towards the mean for serum lipid fractions in patients followed for a varied duration.

We evaluated the deviation towards the mean and attempted to quantify it among the different lipid fractions in patients. The study was done retrospectively on patients who were judged to be metabolically stable and had repeated total cholesterol (TC), high density lipoprotein cholesterol (HDL) and triglyceride (TG) measured in a single laboratory with known coefficient of variation for repeated measurements. The patients and their data were separated into 3 groups. Group A (56 patients) evaluated the difference between the first and its average obtained from an average of 4 samples per patient within a mean of 9 months. Group B, examined pairs of data taken an average of 12 months apart. Group C, evaluated 45 patients with at least 3 data points each a year apart. Linear correlations were applied for the repeats versus the first samples. Highly significant correlations were obtained for all the groups. The slopes were less than one (generally between 0.66 and 0.85) and intercepts had positive values. This was seen even for the HDL whose range of values span 25 to 85 mg per cent. These results strongly supported deviation towards the mean such that from our calculation and in this population, a person with an initial TC of 200 mg per cent would have from 37 to 61 per cent chance of obtaining a significantly higher value if the test was repeated. The magnitude of the change would average 30 mg per cent for cholesterol and as much as 30 per cent of the initial values for TG. In this evaluation, the time intervals between repeats did not appear to influence the result. Yearly follow-up also did not seem to exhibit the effect of aging. However, the latter 2 conclusions rested on a small number of observations. It is suggested that several repeated estimations of these lipid fractions be done before a decision is made towards intervening. In instances of epidemiological studies, it is imperative to obtain representative repeated measurements since this deviation towards the mean will alter the slope of the events versus the lipid-variables.

Prevalence of coronary heart disease and major cardiovascular risk factors in Thailand.

BACKGROUND: Coronary heart disease (CHD) is expected to become one of the major health problems in developing countries such as Thailand where prevalence data are scarce. This study reports the prevalence of CHD, as indicated by electrocardiogram (ECG) Minnesota coding, and its risk factors in Thailand. METHODS: In 1991 we conducted a cross-sectional ECG survey in a multistage random sample of the Thai population, aged > or =30. All major cardiovascular risk factors were measured. Standard supine 12-lead ECG data were collected; amplitudes and intervals were measured manually and entered into a computer. Abnormal tracings were verified by five cardiologists, and agreement among at least three of them was accepted as final. RESULTS: The total sample included 3822 men and 4967 women aged > or =30 years. The age-standardized prevalence rate of CHD was 9.9/1000 (men 9.2/1000, women 10.7/ 1000). The age-standardized level of major cardiovascular risk factors among men and women respectively were: total cholesterol 4.8 mmol/l (187.3 mg/dl), 5.1 mmol/l (197.7 mg/dl); hypercholesterolaemia (> or =6.2 mmol/l) 12.2%, 16.9%; systolic blood pressure (mmHg) 117.8, 117.7; diastolic blood pressure (mmHg) 76.9, 75.8; body mass index (kg/m2) 21.7, 22.8; fasting blood sugar 4.8 mmol/l (87.9 mg/dl), 5.0 mmol/l (90.3 mg/dl); hypertension (> or =160/95 +/- on antihypertensive drugs) 6.3%, 8.1%; smoking 65.1%, 8.5%; diabetes mellitus (> or =7.8 mmol/l) 2.4%, 3.7%; obesity (>25 kg/m2) 15.2%, 27.2%. CONCLUSIONS: Most of the age-adjusted mean values and proportion of major cardiovascular disease risk factors as well as the prevalence of total CHD in the Thai population were much lower than the median of those values found in developing countries.

Nonlinear model for capillary-tissue oxygen transport and metabolism.

Oxygen consumption in small tissue regions cannot be measured directly, but assessment of oxygen transport and metabolism at the regional level is possible with imaging techniques using tracer 15O-oxygen for positron emission tomography. On the premise that mathematical modeling of tracer kinetics is the key to the interpretation of regional concentration-time curves, an axially-distributed capillary-tissue model was developed that accounts for oxygen convection in red blood cells and plasma, nonlinear binding to hemoglobin and myoglobin, transmembrane transport among red blood cells, plasma, interstitial fluid and parenchymal cells, axial dispersion, transformation to water in the tissue, and carriage of the reaction product into venous effluent. Computational speed was maximized to make the model useful for routine analysis of experimental data. The steady-state solution of a parent model for nontracer oxygen governs the solutions for parallel-linked models for tracer oxygen and tracer water. The set of models provides estimates of oxygen consumption, extraction, and venous pO2 by fitting model solutions to experimental tracer curves of the regional tissue content or venous outflow. The estimated myocardial oxygen consumption for the whole heart was in good agreement with that measured directly by the Fick method and was relatively insensitive to noise. General features incorporated in the model make it widely applicable to estimating oxygen consumption in other organs from data obtained by external detection methods such as positron emission tomography.

Observation on the short and long term response to anti-lipemic drugs in southern Thailand.

Patients with dyslipidemia were evaluated with regard to the 5 drugs regimen: simvastatin (average dose, 11.8 mg/day), gemfibrozil (dose 963 mg/day), bezafibrate (433 mg/day), fenofibrate (211 mg/day) and acipimox (667 mg/day). The responses to the drug were divided into different time periods and the magnitude of responses were presented either as average changes in per cent from baseline or as proportion of patients (also in %) whose levels changed by a predetermined percentage. These predetermined percentage took into account the variation observed among patients who had more than 3 measurements during baseline. These levels for significant changes were 16 per cent for total cholesterol (TC), 25-30 per cent for high- and low-density lipoprotein (HDL and LDL), and 44 per cent for triglyceride (TG). Our subjects responded to the drugs within the range reported by other investigators except for acipimox which produced no alteration. Sixty to 100 per cent of patients reduced their TC by 16 per cent with an average change in TC of around -16 per cent to -24 per cent. Simvastatin and fenofibrate appeared most effective in altering TC. The HDL increased 10 per cent to 29 per cent depending on the drug but in terms of proportion that responded by an increment greater than 25 per cent, this was seen in only 23 per cent to 45 per cent of the patients. Long term follow-up which was possible only on 42 patients showed 11 who lessened their response and 6 whose response became more marked.(ABSTRACT TRUNCATED AT 250 WORDS)

Intravenous followed by oral antimicrobial therapy for staphylococcal endocarditis.

Nine men with ten episodes of staphylococcal endocarditis with valvular vegetation (except one) were treated with intravenous cloxacillin for an average of 10 days and followed by oral cloxacillin or dicloxacillin, both with probenecid, for a total duration of 4 wks. Monitoring of serum bactericidal titers (SBT) showed similar values between the two routes of therapy. All patients were bacteriologically and clinically cured. However, there were 3 recurrences, 2 were drug abusers. One nonabuser had the same staphylococcal species 8 months later. All survived the second episode. This preliminary study supports the contention that intravenous followed by oral therapy for staphylococcal endocarditis may be a viable and a more economical form of therapy.

In-hospital and follow-up mortality of patients with acute myocardial infarction.

Patients with definite acute MI who were admitted to Songkla University Hospital between 1982 and 1990 were studied. The 195 patients and 202 admissions were nearly equally distributed between these 65 and older versus those younger than 65. Three quarters were males. The in-hospital mortality was 19.5 per cent and 76.3 per cent of the deaths were from heart failure. Neither age nor gender determined the mortality once corrected for the Killip's staging. There was no difference in mortality when comparing Q versus non-Q MI, anterior versus inferior wall MI or males versus females. One hundred and thirty-eight patients could be followed for and average of 27.1 months. First year mortality was 11 per cent and the first 2 years was 14 per cent. The in-hospital mortality, representing the prethrombolytic era, appeared to be similar to values reported from the Thai and Western literature. The predominance of death from heart failure rather than from arrhythmia may be a consequence of delayed admission whence arrhythmic death had already occurred or patients will seek hospital advice only if highly symptomatic.

Streptococcal endocarditis treated with two-week antibiotic regimen: preliminary report of a partial oral regimen.

We reported 18 consecutive patients with penicillin-sensitive streptococcal IE (infective endocarditis). Twelve were successfully treated with a 2-wk course of penicillin G sodium (PGS) and gentamicin, the dosages of which were guided by minimal inhibitory concentration, minimal bactericidal concentration and serum bactericidal titer (SBT), followed by another six who were treated equally successfully with a one week PGS followed by a second week of amoxycillin together with the usual 2 wks of gentamicin. It is believed that oral therapy, after the initial 2-3 days of parenteral antimicrobial, may be adequate for penicillin-sensitive streptococcal IE.

Precipitous hypotension after nifedipine in pheochromocytoma: report of 2 cases.

Two patients with pheochromocytoma initially responded to oral or sublingual nifedipine with marked reduction in systolic blood pressure (range 50-160 mmHg) without concomitant increment in the heart rate or clinical consequences. This could possibly be due to the combination of hypovolemia and negative inotropism.

Double-blind evaluation of enalapril in patients with systolic heart failure.

Fifty-six patients with a mean age of 58 years, 14 females and 42 males, all with dominant systolic heart failure (33 in functional class 3 and 4) were randomised to receive either added placebo or added enalapril to their heart failure medication. There were 13 patients in this group who had their trial drug switched after a certain period to allow direct but blind comparison between placebo and enalapril. Cardiac mortality with enalapril was 32 per cent compared to 48 per cent with placebo at intervals after initiating therapy of 20.0 +/- 19.4 versus 14.3 +/- 11.5 months respectively. When compared to a preceding control period, 80 per cent of the enalapril patients improved in contrast to 21 per cent of the placebo. However, when a comparison was made directly between enalapril and placebo, enalapril was better in 31 per cent and placebo was better in 8 per cent of the patients. It is concluded that in certain patients with systolic heart failure from non-valvular and non-hypertensive causes, enalapril is beneficial when added to the conventional treatment. An argument is also presented that to cost-effectively identify the group who will benefit, a short term ACE-I trial after the conventional antifailure therapy can be considered in all patients with systolic heart failure.

Embolism and atrial fibrillation. A longitudinal follow-up.

Six hundred and forty-nine patients with proven chronic atrial fibrillation were followed for a total of 1,436 patient-years without anticoagulation. The patient were divided into 7 disease groups with each having an average age ranging from 39 to 69 years. Eleven per cent of the patients had systemic embolism prior to being registered for the follow-up. The diseases which had the highest incidence of embolism prior to being followed were the same as those producing the highest rate of systemic embolism while under observation. The disease groups were rheumatic valvular (predominantly mitral stenosis) and ischemic heart diseases. Their embolic rate were 3.9 to 5.1 emboli per 100 pt-yr. Other disease groups with lower embolic rates of 0 to 0.9 per 100 pt-yr were heart failure, non-rheumatic mitral regurgitation, atrial septal defect and thyrotoxicosis. Since the incidence of systemic embolism varied according to the primary disease, and since the hemorrhagic complication of anticoagulant therapy is finite, it is advised that low risk group may not benefit greatly from anticoagulation. However, the true low risk group has still to be properly determined.

Patients with prosthetic cardiac valves followed in southern Thailand.

Prospective follow-up of 174 post-prosthetic cardiac valves have been done at Prince of Songkla University and Hat Yai Regional hospitals since 1985. The total follow-up time was 549 patient-years (pt-yr). Thirty per cent had been followed for 1 year or less. Eighty-two per cent of the patients had their mitral valves replaced either singly or as part of a multiple replacement. Thirty per cent of the time, the prothrombin time was below therapeutic range. Major events did not appear to be different from other reports: 2.7 embolic events per 100 pt-yr, 3.2 major bleeds and 3.2 deaths which may eventually be as high as 4.4 if a portion of the lost patients was assumed to have died. Events related to prosthetic valves and anticoagulation seemed to occur predominantly 1-2 years after surgery.

Trimetazidine and stable angina a double-blind trial.

The effect of trimetazidine was evaluated in patients with stable angina by adding it to the other antianginal regimen in a double blind crossover design each of 8 week's duration. The method of evaluation made use of symptom recall, daily dairy of the intake of sublingual nitrates or of anginal discomfort and in some, symptom limited treadmill exercise stress test (EST). Thirty-six patients completed the trial. Symptom-wise, 16 patients could not differentiate the effect of the true tablet from the placebo. Eight had less and 12 had more angina while on the drug. Of the 17 evaluable EST, 9 showed no change in the degree of ischemic changes while 4 performed with less and 4 with more ischemia while on the drug. Symptom-wise and taking into account the pre and post trial periods, a placebo effect was not found to be dominant. It is concluded that trimetazidine does not improve angina among those already being treated with conventional doses of nitrates, beta and calcium blockers.

Is routine pre-operative electrocardiogram necessary?

Among 3,371 ECG (electrocardiograms) performed at Hat Yai Municipal hospital in 1981, at least 424 were done presumably for a routine preoperative investigation. Analysing the data file of each patient, it was found that 14 per cent had definitely abnormal ECGs of the type that generally implies ischemic heart disease. Another 9 per cent had ECGs that were possibly abnormal and needed, at least, a medical evaluation. However, only a fifth (22 out of 100) of those with abnormal ECGs were eventually examined and of these, less than half (9 out of 22) had their management altered. These results suggest that routine preoperative ECG lacks the potential usefulness given constraints present in several health centers in this country.

Diffusional arteriovenous shunting in the heart.

Previous indicator dilution experiments in isolated blood-perfused dog hearts suggested that there was intramyocardial diffusional shunting of water relative to a flow-limited solute, antipyrine. Two sets of studies have been done to assess the importance of this shunting, since it implies the possibility of a diffusional bypass for oxygen and other substances, which may be important in ischemia. Nonconsumed tracers were used to show the phenomenon. In the first set, bolus injections of 133Xe dissolved in saline were made into the coronary inflow and the tracer content of the organ recorded by an external gamma detector. The initial Xe washout was disproportionately rapid at low flows, and the late phase was also relatively retarded. In the second set, boluses of cool saline containing indocyanine green were injected into the coronary arterial inflow while coronary sinus outflow dilution curves were recorded via a thermistor and a dye densitometer over a wide range of flows. The thermal curves showed emergence of heat preceding the dye; the degree of precession was much greater at low flows, and, unlike the dye curves, the thermal dilution curves showed dramatic differences in shape at different flows. A model for diffusional countercurrent exchange shows similar changes in residue curves and outflow dilution curves. The conclusion is that there is diffusional shunting of small lipid-soluble molecules whose diffusion coefficients in tissue are high. While the shunting of heat is great, the shunting of soluble gases will not be large and that of normal substrates will be negligible.

Cardiac tamponade in dogs with normal coronary arteries. II. Myocardial flow and metabolism with moderate and severe hemodynamic impairment.

To determine the effects of cardiac tamponade on myocardial blood flow and its distribution, dogs were prepared with indwelling pericardial catheters. Hemodynamic, myocardial blood flow, and myocardial metabolic data were collected in 5 closed-chest, spontaneously breathing animals with normal blood volumes and hemoglobin concentrations and 6 with acute anemia. Instillation of an average of 89.0 +/- 14.9 ml of modified Normosol into the pericardial space in dogs with normal hemoglobin levels produced mild tamponade with a modest decline in aortic pressure (119.5 +/- 14.3 to 96.8 +/- 12.1 mm Hg) and significant rises in left and right atrial and pericardial pressures to 7-8 mm Hg. Increasing the pericardial volume to 124.0 +/- 13.6 ml produced hypotension (mean aortic pressure 86.2 +/- 10.5 mm Hg) and rises in the left and right ventricular filling pressures and pericardial pressure to 10-11 mm Hg. Total myocardial blood flow fell from 1.19 +/- 0.18 to 0.73 +/- 0.17 ml/min/g (p less than 0.02) during mild tamponade, and fell further to 0.56 +/- 0.17 ml/min/g (p less than 0.05) with more severe tamponade. Despite these declines, the left ventricular wall inner/outer flow ratio and left ventricular flow as a proportion of total cardiac output were unchanged. In dogs with anemia more severe tamponade was created, with consequently more marked hemodynamic abnormalities. However, the relative changes in myocardial blood flow and inner/outer flow ratio were similar. Myocardial metabolic parameters could be evaluated only in the dogs with less severe tamponade.(ABSTRACT TRUNCATED AT 250 WORDS)

Cardiac tamponade in dogs with normal coronary arteries. I. Effect of changing intravascular volume on hemodynamics and myocardial blood flow.

Intravascular volume expansion has been shown to improve cardiac output in experimental cardiac tamponade. To determine the limitations of intravascular volume manipulation, acute tamponade was created in 20 anesthetized, spontaneously breathing dogs. The intrapericardial volume causing tamponade was determined for each animal, and kept constant. Hemodynamics were recorded with and without tamponade at multiple levels of intravascular volume. During cardiac tamponade, intravascular volume expansion increased cardiac output only in animals which were initially volume-depleted. Volume expansion of normovolemic or hypervolemic animals caused minimal changes in cardiac output, but increased atrial and aortic pressures. Intravascular volume depletion of the normovolemic animal caused a significant decline in cardiac output, in contrast to the trend towards an increased output following phlebotomy of the volume-expanded animals. In general, the benefit of intravascular volume expansion during cardiac tamponade could only be demonstrated when atrial pressures were below 12 mm Hg.

Impaired coronary flow and ventricular function in hearts of hypertensive rats.

Hearts of rats made hypertensive (BP greater than 150 mmHg) by left renal artery clipping and sham operated controls were studied in two series of experiments. In series I, cardiac function was studied in an isolated working heart apparatus at weeks 4, 9 to 10 and 16 to 17 post-surgery. In series II, coronary flow was studied during normoxic and anoxic retrograde perfusions at days 6 to 9 and at weeks 4 and 10 post-surgery. In series I, when compared with controls, hypertensives had lower body weights at weeks 4 and 9 to 10, and higher left ventricular weights at each period. Heart function was depressed for hypertensives when compared with controls as measured by lower stroke volume, peak left ventricular systolic pressure, stroke work, ejection fraction, positive dP/dt, peak aortic flow, and maximal flow acceleration. Relaxation rate as measured by negative dP/dt was also depressed. Hearts from hypertensives had significantly lower coronary flows and MVO2, and increased percent oxygen extraction and effluent lactate/pyruvate ratios. LVEDP was significantly elevated for hypertensives, when LVEDV (ml) was similar for hypertensives and controls. Myocardial actomyosin ATPase activity was depressed for hypertensives at weeks 9 to 10 and 16 to 17 post-surgery. In series II, when hearts were perfused retrogradely, coronary flow was lower for hypertensives than for controls during normoxia at days 6 to 9 and at week 4, and during anoxia at all time periods. The findings demonstrate that impaired coronary vascular reserve develops within days of the development of hypertension in rats, and this can be associated with impaired ventricular function.

Gamma camera quantitation of thallium-210 redistribution at rest in a dog model.

Defects seen at rest on thallium-201 (201TI) scintigraphy can disappear over time. We obtained sequential 5-minute scans over 127 +/- 9.4 minutes in seven open-chest dogs with fixed, stable regional flow reductions (normal zone flow 0.76 +/- 0.09 ml g-1/min, ischemic zone flow 0.49 +/- 0.04 ml g-1 min [mean +/- SEM], p less than 0.05) as determined by microsphere injection. Sequential 5-minute scans were obtained after i.v. injection of 1.5 mCi of 201TI. Data were stored in a 64 x 64 pixel computer matrix. Qualitatively, defects that showed redistribution were seen in all dogs. Quantitatively, greater count loss from peak activity distinguished the normal zone, but overlap was great. Alternate quantitative methods using background subtraction altered the characteristics of the time-activity curves, but did not enhance the separation of ischemic from normal zones. Patterns of 201TI redistribution from gamma camera imaging are profoundly influenced by the method of quantitation. No single method of quantitative analysis separated ischemic from normal zones in all dogs. The clinical significance of patterns at rest requires redefinition.