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Biomedical subjects

S D Pringle

Publications and source records attributed to S D Pringle.

At least 19 recordsLinked to original sources
PubMed1992

A new classification of left ventricular geometry in patients with cardiac disease based on M-mode echocardiography.

M-mode echocardiograms of 202 cardiac patients were studied with respect to the pattern of left ventricular (LV) geometry. Patients with normal LV mass and volume were separated from those who had LV hypertrophy or enlargement on the basis of LV mass and volume indexed to body surface area. The relative wall thickness that is currently used to classify LV hypertrophy/enlargement was found to be inadequate for differentiating between concentric and eccentric types of LV hypertrophy. A new M-mode echocardiographic classification is therefore proposed that accurately separates the different types of LV enlargement; it also allows identification of patients who have chronically dilated left ventricles at the expense of thin walls and thus have normal LV mass.

Cardiomegaly↗
PubMed1992

Significance of ventricular arrhythmias in systemic hypertension with left ventricular hypertrophy.

Hypertensive patients with the electrocardiographic (ECG) pattern of left ventricular (LV) hypertrophy and strain are at increased risk of sudden death. It has been suggested that ventricular arrhythmias may be responsible. The prevalence and significance of ventricular arrhythmias was therefore studied in 90 hypertensive patients with LV hypertrophy and strain by undertaking 48-hour ambulatory ECG monitoring, ECG signal-averaging and programmed ventricular stimulation. Complex ventricular ectopic activity (Lown grade greater than or equal to 3) was detected in 59 patients (66%). Eleven patients (12%) had episodes of nonsustained ventricular tachycardia. There were no sustained arrhythmias either on ambulatory ECG monitoring or induced by programmed ventricular stimulation. Only 1 patient had ventricular late potentials recorded by the signal-averaged electrocardiogram. Therefore, there was little to suggest an underlying arrhythmogenic substrate in these patients. In conclusion, whereas ventricular arrhythmias occur often in patients with LV hypertrophy associated with systemic hypertension, their significance, if any, remains to be established.

Adult↗
PubMed1992

Variable patterns of ST-T abnormalities in patients with left ventricular hypertrophy and normal coronary arteries.

BACKGROUND: Classically, the ST-T configuration in the electrocardiogram of patients with left ventricular hypertrophy is said to have a typical pattern of ST depression together with asymmetrical T wave inversion (the so-called left ventricular strain pattern). However, many patients with left ventricular hypertrophy may also have ischaemic heart disease. To revise the electrocardiographic criteria for left ventricular hypertrophy the ST-T configuration in patients with left ventricular hypertrophy documented by echocardiography and with normal coronary arteries was assessed. METHODS: 24 patients were selected for this study. All had left ventricular hypertrophy documented by echocardiography, normal coronary arteries by cardiac catheterisation, and ST and/or T wave abnormalities in the lateral leads of their electrocardiogram. There were eight patients with aortic valve disease and 16 with hypertension who had coronary angiography as part of an investigation into the risk factors of sudden cardiac death caused by hypertensive left ventricular hypertrophy. No patient was receiving digitalis preparations or had electrolyte disturbances, and none had a previous myocardial infarction or ventricular conduction defect. RESULTS: Typical electrocardiographic evidence of left ventricular strain was found in approximately two thirds (63%) of patients and 95% of this subgroup had asymmetrical T wave inversion. Flat ST segment depression, with or without T wave inversion or isolated T wave inversion (symmetrical or asymmetrical) in the anterolateral leads, was seen in the remaining 37% of patients. CONCLUSIONS: These findings indicate that left ventricular hypertrophy without coronary artery disease can cause variable types of ST-T abnormalities in the anterolateral leads including the typical left ventricular strain pattern and non-specific ST-T changes. Non-specific abnormalities could not be distinguished from those of coronary artery disease and may adversely affect the accuracy of the electrocardiographic criteria for the diagnosis of left ventricular hypertrophy because they do not accord with the criteria for left ventricular strain.

Adult↗
PubMed1992

Symptomatic and silent myocardial ischaemia in hypertensive patients with left ventricular hypertrophy.

OBJECTIVE: To assess the prevalence of symptomatic and silent myocardial ischaemia in patients with hypertensive left ventricular hypertrophy. DESIGN: Cross sectional study. SETTING: University department of medical cardiology. PATIENTS: 90 patients (68 men and 22 women; mean age 57 (range 25 to 79)) with left ventricular hypertrophy due to essential hypertension. INTERVENTIONS: 48 hour ambulatory ST segment monitoring (all patients), exercise electrocardiography (n = 79), stress thallium scintigraphy (n = 80), coronary arteriography (n = 35). RESULTS: 43 patients had at least one episode of ST segment depression on ambulatory electrocardiographic monitoring. The median number of episodes was 16 (range 1 to 84) with a median duration of 8.6 (range 2 to 17) min. Over 90% of these episodes were clinically silent. 26 patients had positive exercise electrocardiography and 48 patients had reversible thallium perfusion defects despite chest pain during exercise in only five patients. 18 of the 35 patients who had coronary arteriography had important coronary artery disease. Seven of these patients gave no history of chest pain. CONCLUSIONS: Symptomatic and silent myocardial ischaemia are common in hypertensive patients with left ventricular hypertrophy, even in the absence of epicardial coronary artery disease.

Adult↗
PubMed1992

Electrocardiographic changes during cesarean section under regional anesthesia.

To determine electrocardiographic changes and whether myocardial ischemia occurs during cesarean section, electrocardiograms were recorded continuously using Holter monitoring in 25 patients undergoing elective cesarean section under either spinal or epidural anesthesia. In addition, in 13 of the patients, two-dimensional precordial echocardiography was carried out before and during cesarean section. ST segment depression suggestive of myocardial ischemia occurred in 16 patients including 8 of the 13 with echocardiograms. Wall motion remained entirely normal during episodes of ST segment depression. Patients in whom ST depression developed had significantly more rapid heart rates at delivery than those who did not experience ST depression. We conclude that ST segment depression is a common feature of the electrocardiogram during cesarean section under regional anesthesia and is not the result of myocardial ischemia.

Anesthesia, Conduction↗
PubMed1991

Reference values and reproducibility of Doppler echocardiography in the assessment of the tricuspid valve and right ventricular diastolic function in normal subjects.

The Doppler echocardiographic indexes of the tricuspid and mitral valves were assessed in 74 normal subjects (35 women and 39 men, mean age 45 years). A reproducibility study was also performed to examine the various sources of technical and biological variability. There were significantly higher peak early and late flow velocities across the mitral valve than across the tricuspid valve (0.67 +/- 0.13 and 0.47 +/- 0.12 vs 0.51 +/- 0.08 and 0.35 +/- 0.09 m.s-1, respectively; all p less than 0.0001). There was no significant difference between the early:late (E:A) velocity ratios of the 2 valves (1.65 +/- 0.73 vs 1.75 +/- 0.67, p less than 0.01). There was a steeper mitral early deceleration slope (-3.59 +/- 1.07 vs -2.95 +/- 0.91 m.s-2) but no significant difference in pressure half-times across the 2 valves (47 +/- 7 vs 51 +/- 12 ms, p less than 0.1). No influence of gender or body surface area could be demonstrated. There was a weak but significant relation between mitral peak early, peak atrial velocity and E:A ratio and age (r = -0.39, p less than 0.001, r = 0.23, p less than 0.01, and r = -0.245, p less than 0.01, respectively). There was no significant correlation between any of the tricuspid flow parameters and age. Respiration caused pronounced variability in the tricuspid Doppler indexes and all tricuspid flows were sampled and analyzed only during inspiration. The intra- and interobserver variabilities were small for all of the Doppler indexes measured, but the day-to-day variability was quite significant especially for the pressure half-time, deceleration and acceleration slope values.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Doppler evaluation of a left atrial myxoma.

We present a detailed Doppler evaluation of a left atrial myxoma. Doppler recordings varied considerably with the position of the patient and of the sample volume. Maximum obstruction to flow was observed in the left lateral position; but no gradient was present when sitting upright. These findings provide a haemodynamic explanation for the positional variation of murmurs characteristic of atrial myxomas.

Echocardiography, Doppler↗
PubMed1991

A comparison of left ventricular mass and volume using different echocardiographic conventions.

Left ventricular dimensions were measured on M-mode echocardiograms, both by the Penn Convention and the Recommendations of the American Society of Echocardiographers in a sample cardiac population. The measurements of interventricular septum and the posterior wall of the left ventricle were significantly larger (P less than 0.001) using American Society Recommendations compared to using the Penn Convention. However, the left ventricular internal dimension at end-diastole was significantly larger (P less than 0.001) when measured by the Penn Convention. As a result of the differences in left ventricular dimensions, the left ventricular mass indexed to body surface area was significantly higher (P less than 0.001) using American Society as opposed to Penn measurements. On the other hand, left ventricular volume indexed to body surface area was significantly higher (P less than 0.001) on Penn measurements than on American Society estimates. These differences should be considered in any study where criteria of normality are to be applied. Good positive correlation (r greater than 0.9) between Penn and American Society estimates of indexed left ventricular volume allowed development of a regression equation to convert volumes from one convention to another. As a result, an upper normal limit of 100 ml/m2 for indexed left ventricular volume is suggested for measurements made using the Penn Convention.

Cardiomegaly↗
PubMed1991

Hypertension and coronary artery disease. Can the chain be broken?

Hypertension is an established risk factor for all the clinical sequelae of coronary artery disease. Despite this, individual therapeutic trials of antihypertensive therapy have not demonstrated the expected reduction in coronary morbidity and mortality. This apparent failure is perhaps not surprising when one considers the multifactorial nature of coronary artery disease and the different ways in which hypertension may affect the coronary circulation. Much debate has also centered on the antihypertensive therapy used in major trials in that it may in some way prevent the reduction in coronary mortality. However, thus far no clear evidence of a harmful effect has emerged. Reducing coronary mortality in hypertensive patients is a major challenge but one that can be effectively surmounted by approaching these different factors in a concerted manner. The ultimate goal must be to prevent the development of hypertension and left ventricular hypertrophy, but until such time as that can be achieved, the early detection of hypertension is mandatory. The optimal levels of systolic and diastolic blood pressures must be established. Studies on the more recent antihypertensive agents hold promise for a more specific effect on the atherosclerotic process as well as sustained control of arterial blood pressure. In this regard, it would seem essential to develop more precise ways of quantifying atherosclerosis and thus clarifying the nature of its relation to hypertension. Finally, management of hypertension must include precise assessment of the patient's overall cardiovascular risk status and appropriate and aggressive management of all risk factors for coronary artery disease.

Animals↗
PubMed1990

Simultaneous measurement of left ventricular function and perfusion.

A new radiopharmaceutical, methylisobutyl isonitrile (MIBI), has been developed as a technetium-99m-labelled alternative to thallium 201 for myocardial imaging. By virtue of the high specific activity of 99mTc, some 600 MBq may be administered as a 0.3 ml bolus, permitting the acquisition of a first-pass nuclear angiogram at rest and at peak exercise. The agent was assessed in ten sequential patients referred for routine cardiac catheterisation, who also underwent an exercise electrocardiographic (ECG) test. Good quality nuclear angiograms, planar perfusion and tomographic perfusion images were obtained; the results correlated well with the catheterisation data. Of 30 myocardial segments for which wall motion was judged normal/abnormal from the nuclear angiogram, results concordant with contrast studies were obtained in 27 (90%). In the case of the 50 segments analysed from the perfusion images, concordant results were obtained in 43 (86%) from the planar studies and in 42 (84%) from the tomographic studies. All normal segments were classified correctly.

Adult↗
PubMed1990

Left ventricular hypertrophy and mortality in hypertension: an analysis of data from the Glasgow Blood Pressure Clinic.

Three thousand seven hundred and eighty-three patients with non-malignant hypertension attending the Glasgow Blood Pressure Clinic between 1968 and 1983 were followed prospectively for an average of 6.5 years. Left ventricular hypertrophy (LVH) was present at the outset in 34.5% of the men, and 12.8% had ST-T changes. The corresponding figures for women were 21.5% and 8.8%. The prevalence of LVH increased with the severity of hypertension and was higher for a given blood pressure level in men than in women. All-cause age-adjusted mortality, expressed as deaths per 1000 patient-years, was 27.6 for men with normal electrocardiographs, 43.2 for men with LVH only (P less than 0.001) and 56.9 for men with LVH and ST-T changes (P less than 0.001). Similar trends were seen in women. The excess risk associated with LVH, with or without ST-T changes, could not be explained by age, increased blood pressure at referral to the clinic, or smoking habit, when these factors were considered either separately or in combination (regression analysis). Thus, our study demonstrates that LVH, with or without ST-T changes is an independent risk factor for mortality in hypertensive patients.

Age Factors↗
PubMed1990

The safety of felodipine.

Hypertensive patients, particularly the elderly, may often suffer from other diseases. Therefore, antihypertensive compounds should not negatively affect such disorders. Felodipine is a calcium antagonist that has potentially beneficial effects in angina pectoris and congestive heart failure. Further, it does not adversely affect lung function in asthmatic patients or glucose tolerance in patients with diabetes. Preliminary investigations also indicate that felodipine has no negative influence on plasma lipid levels. Although felodipine seems to be safe in most patients, treatment with felodipine should at present be avoided in pregnant women, since digital anomalies have been observed in rabbit fetuses. The adverse effects seen during treatment with felodipine are usually mild and transient and generally related to the vasodilatory action of the drug, the most common being ankle edema, headache, flushing, dizziness, and palpitations. The only significant drug interactions with felodipine occur with inducers and inhibitors of the cytochrome P-450 system, which is responsible for the metabolism of felodipine.

Animals↗
PubMed1989

Comparison of enalapril and atenolol in mild to moderate hypertension.

PURPOSE: Short-term therapy with angiotensin converting enzyme (ACE) inhibitors for hypertension is effective and well tolerated, and compared with beta blockers, may cause fewer adverse reactions. Furthermore, enalapril has been observed to have a greater effect on systolic blood pressure than beta blockers. We therefore decided to compare the ACE inhibitor enalapril and the beta blocker atenolol as monotherapy in a double-blind study of patients with mild to moderate hypertension. PATIENTS AND METHODS: After a four-week placebo run-in period, 162 patients were allocated randomly to receive atenolol (50 to 100 mg daily) or enalapril (20 to 40 mg daily) for 12 weeks. To assess the influence of these drugs on quality of life, a series of psychologic tests was performed, and a subset of patients also underwent treadmill exercise and pulmonary function tests. RESULTS: In 147 patients who completed the study, enalapril reduced supine blood pressure by 19/12 mm Hg, compared with 9/7 mm Hg for atenolol (p less than 0.001/p less than 0.005). The modest blood pressure response to atenolol was not due to poor compliance. A target blood pressure of 140/90 mm Hg or less was achieved by 35 percent of enalapril-treated atenolol (p less than 0.01). The frequency and severity of adverse effects with the two drugs were similar, and few important differences emerged from the quality-of-life assessments. CONCLUSION: At the doses used, enalapril induced a greater short-term blood pressure response than atenolol; long-term studies of its safety and efficacy are required.

Adolescent↗
PubMed1989

Infective endocarditis caused by Streptococcus agalactiae.

We report a series of five cases of infective endocarditis caused by Streptococcus agalactiae (group B streptococcus) in Glasgow over a 30 month period. There were three males and two females mean age 48.6 years (range 28-63 years). Only one patient had previous valvular heart disease. The infections were characterised by an acute presentation and an aggressive course with major arterial emboli. Despite early diagnosis and appropriate intravenous antibiotics three patients died, one after valve replacement and two before surgery could be undertaken. The remaining two patients had successful valve surgery and have recovered. S. agalactiae endocarditis is an uncommon but important condition which carries a high mortality. The infection is difficult to control with antibiotics alone and therefore early surgery may be indicated.

Adult↗
PubMed1989

Pathophysiologic assessment of left ventricular hypertrophy and strain in asymptomatic patients with essential hypertension.

To investigate the significance of the electrocardiographic (ECG) pattern of left ventricular hypertrophy and strain, two groups of asymptomatic patients with essential hypertension were compared. The patients were similar in terms of age, smoking habit, serum cholesterol and blood pressure levels, but differed in the presence (Group I, n = 23) or absence (Group II, n = 23) of the ECG pattern of left ventricular hypertrophy and strain. Group I patients had significantly more episodes of exercise-induced ST segment depression (14 versus 4, p less than 0.05) and reversible thallium perfusion abnormalities (11 of 23 versus 3 of 23, p less than 0.05) despite similar exercise capacity and absence of chest pain. Nonsustained ventricular tachycardia was detected on 24 h ambulatory ECG monitoring in two patients in Group I, but no patient in Group II. Coronary arteriography performed in 20 Group I patients demonstrated significant coronary artery disease in 8 patients. This study has shown that there is a subgroup of hypertensive patients with ECG left ventricular hypertrophy and strain who have covert coronary artery disease. This can be detected by thallium perfusion scintigraphy, and may contribute to the increased risk known to be associated with this ECG abnormality.

Angiography↗