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Biomedical subjects

G Jackson

Publications and source records attributed to G Jackson.

At least 271 records · Page 15Linked to original sources
PubMed1987

Doppler echocardiographic appearance of cusp tears in tissue valve prosthesis.

Characteristic Doppler echocardiographic abnormalities were noted in five patients with a failing tissue prosthesis shown to have severe regurgitation and no evidence of obstruction. The audio signal was musical in quality and the regurgitant flow pattern was bidirectional and striated. There were 4 to 6 striations in the mitral and 18 in the aortic regurgitant jets per 100 cm/s length of signal. Pulsed Doppler ultrasound localized the jet to the valve in all cases although angiography failed to localize it in one of four cases. At surgery each valve had a tear in or partial disintegration of one cusp whereas the other two cusps were intact, mobile and of normal thickness. The Doppler appearance is thought to be caused by fluttering of the disrupted cusp leading to the shedding of families of vortices in both a retrograde and an orthograde direction. It is suggested that this is likely to be a useful sign for the diagnosis of cusp tears.

Adult↗
PubMed1987

Transvenous cardioversion for the management of recurrent ventricular arrhythmias.

The efficacy of transvenous cardioversion and defibrillation for treating life threatening spontaneous ventricular arrhythmias was assessed in a study of 17 patients in a cardiac care unit. Eleven had ventricular tachycardia, five had ventricular fibrillation, and one had both. Transvenous cardioversion successfully terminated tachyarrhythmias on 42 separate occasions in ten patients. Stable electrode positions could not be achieved in two patients, recurrent late displacement occurred in one, and four patients had no further arrhythmias requiring cardioversion once the lead was placed. The energy levels required for successful cardioversion ranged from 0.05 J to 25 J for ventricular tachycardia and from 1 J to 25 J for ventricular fibrillation. The nine successful shocks of 1 J or less did not require sedation or general anaesthesia. High energy (25 J) endocardial shocks were unsuccessful in terminating arrhythmias in two patients, one with ventricular tachycardia and the other with both ventricular tachycardia and fibrillation. Minor unwanted effects of endocardial shocks occurred in five patients. These were acceleration of ventricular tachycardia in two patients and complications of pacing via the special lead in three others: failure of sensing occurred in all three and one patient also had a transient rise in pacing threshold. A postmortem examination in one patient who had received three unsuccessful high energy shocks revealed localised endocardial necrosis at the site of the distal electrode. Transvenous cardioversion offers advantages over external cardioversion but at present practical difficulties limit its application to patients with recurrent ventricular arrhythmias that cannot readily be controlled by conventional methods.

Aged↗
PubMed1986

Bilateral internuclear ophthalmoplegia in systemic lupus erythematosus.

The case of a 25-year-old female with bilateral internuclear ophthalmoplegia as a presenting feature of systemic lupus erythematosus (SLE) is described. It is important to recognize that bilateral internuclear ophthalmoplegia may be an early manifestation of cerebral involvement in SLE in addition to its occurrence in multiple sclerosis.

Adult↗
PubMed1985

Reciprocal change in ST segment in acute myocardial infarction: correlation with findings on exercise electrocardiography and coronary angiography.

The clinical relevance of reciprocal changes in the ST segment occurring at the time of acute myocardial infarction was studied prospectively in 85 consecutive uncomplicated cases. Reciprocal depression of the ST segment was defined as depression of 1 mm or more in electrocardiogram leads other than those reflecting the infarct. All patients underwent maximal, symptom limited treadmill stress testing two weeks after the infarct and coronary angiography six weeks after infarction. Forty six patients had inferior, 34 anterior, and five true posterior infarction. Of the 51 patients with reciprocal changes, 45 (88%) developed exercise induced ST segment depression in areas remote from the infarction zone. At angiography all 45 patients were shown to have stenoses greater than 70% in at least two major vessels. Four patients had negative exercise electrocardiograms and were sequently shown to have single vessel disease subtending their infarct, and the remaining two patients had a false negative treadmill test result. Of the 27 patients without reciprocal changes, 21 (78%) had negative treadmill stress test results associated with single vessel coronary disease. Five had positive stress test results and multivessel coronary disease, and one had a false negative stress test result. The remaining seven patients had ST segment elevation without Q wave formation in the reciprocal areas and were assessed separately. Of these, six had positive stress test results and multivessel coronary disease and one had a negative stress test result and single vessel coronary disease to the infarct area. Twenty one patients with anterior infarcts (62%) and 27 with inferior infarcts (59%) had reciprocal changes. No differences emerged in the relation between infarct site, reciprocal change, and presence of additional coronary disease. At follow up of the 51 patients with reciprocal changes in the ST segment 36 had become symptomatic, of whom 29 had undergone coronary artery bypass surgery. By contrast, only four of the 27 patients without reciprocal changes in the ST segment had developed symptoms, and two of these had undergone coronary revascularisation. Reciprocal ST segment depression at the time of acute myocardial infarction may identify patients with severe coronary disease who are at risk of subsequent cardiac events and appears to be as reliable as results of early postinfarction treadmill stress testing in predicting the underlying coronary anatomy. When the electrocardiogram does not show reciprocal changes treadmill testing provides valuable additional information.

Adult↗
PubMed1985

Oral labetalol in the management of stable angina pectoris in normotensive patients.

The efficacy of labetalol, an alpha and beta receptor antagonist, was evaluated in 12 normotensive patients with stable angina pectoris in a single blind dose ranging study. After a two week period of placebo treatment, labetalol was given in doses of 100, 150, 200, and 300 mg twice daily, each for two weeks. Frequency of angina attacks decreased from 9.4 (SEM 2.3)/week in the control period to 7.3 (2.8), 5.2 (2.6), 3.8 (1.8), and 3.3 (1.9)/week in the four successive treatment periods. In the same periods the number of glyceryl trinitrate tablets consumed decreased from 7.0 (2.6)/week to 5.8 (3.3), 3.9 (2.9), 2.7 (1.8), and 2.6 (2.1)/week. Maximal symptom limited treadmill exercise tests were performed three and 12 hours after dosage at each dose. Exercise tolerance (expressed as seconds of the Bruce protocol) increased from 266 (44) with placebo to 306 (44), 369 (50), 396 (48), and 413 (51) in the four treatment periods. This improvement was accompanied by a significant blunting of the heart rate and blood pressure responses to exercise. Trough point exercise tolerance did not differ significantly from that at three hours after dosage. Thus labetalol is effective as an antianginal agent at doses of 150-300 mg twice daily and is well tolerated by the normotensive patient with angina.

Adult↗
PubMed1985

Increased diastolic blood pressure response to exercise testing when coronary artery disease is suspected. An indication of severity.

One hundred and two consecutive patients with a history of chest pain or recent previous myocardial infarction underwent maximal treadmill stress testing and coronary angiography. The diastolic blood pressure response to exercise was evaluated independently of ST segment change and systolic blood pressure. In the presence of a normal systolic blood pressure response an increase in diastolic blood pressure of 15 mm Hg on at least two determinations during the same stage of exercise was considered abnormal. In 99 patients an accurate diastolic reading was possible. Of these, 61 had a normal diastolic blood pressure response; in 25 of these the ST segment was ischaemic and seven had three vessel coronary artery disease. Thirty eight patients had an abnormal diastolic blood pressure response and 27 of these had an ischaemic ST response. Of the 11 with a negative ST response for ischaemia one had left main stem disease, seven three vessel disease, and three two vessel disease. Patients with an abnormal diastolic response had greater ST depression with more angina at a reduced workload than those with a normal diastolic response. In patients with chest pain an abnormal increase in diastolic blood pressure on exercise reflects severe coronary artery disease. Although no false positives occurred in this study there was an appreciable number of false negatives (sensitivity 46%) in both patients with chest pain and those with infarction. An abnormal diastolic response therefore represents a useful additional diagnostic indicator of coronary artery disease when the ST segment response is normal or borderline. When the diastolic pressure becomes increased with or without ST changes the likelihood of severe coronary artery disease is increased.

Blood Pressure↗