Biomedical subjects
Publications and source records attributed to B E Griffiths.
A 37-yr-old woman with an 8-month history of chest pain, unrelated to exercise, was successfully resuscitated from out-of-hospital cardiac arrest due to ventricular fibrillation. Cardiac catheterisation revealed minor coronary artery disease. Ergometrine injection was associated with complete occlusion of the left anterior descending coronary associated with identical chest pain and pronounced ST-segment changes.
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We measured plasma nitrate levels and haemodynamics following sublingual glyceryl trinitrate (GTN) (0.5 mg), or isosorbide dinitrate (ISDN) administered intravenously (0.5 mg) or by inhalation (1.25 mg) in 23 patients undergoing cardiac catheterisation for investigation of chest pain. Peak levels were detected at 90 s and 5 min following intravenous and inhaled ISDN respectively and at 3 min following sublingual GTN. Intravenous and inhaled ISDN produced similar plasma levels at 30 s and both were significantly greater than following sublingual GTN. Plasma levels were maintained for longer following inhaled ISDN than intravenous ISDN or sublingual GTN. Haemodynamic responses were qualitatively similar following each treatment; reduction in pulmonary vascular resistance and pressure and left ventricular end diastolic pressure occurred in each group. Heart rate, cardiac output and LV dP/dt.P-1 remained unchanged. Maximal haemodynamic responses were greater following ISDN than GTN, with little difference between the two preparations of ISDN. Haemodynamic responses were more sustained following inhaled ISDN than following sublingual GTN or intravenous ISDN, the latter two being similar in this respect. These findings suggest that inhaled ISDN may provide more rapid and sustained relief from angina than sublingual GTN.
During a 34-month period, 370 Medtronic-Hall valves were implanted into 310 patients. Twenty-four percent of patients had additional operative procedures. Hospital mortality was 7% and late mortality to date is 3%. No deaths were due to thromboembolic complications or mechanical failure of the valve. The overall embolic rate was 2.5 per 100 patient years. For mitral valve replacement, the embolic rate was 3.5 per 100 patient years. Patients with isolated mitral valve replacement were subjected to detailed clinical and echocardiographic assessment. Eighty-nine percent of patients with 29 or 31 mm mitral prostheses improved one NYHA class or more and 33% improved 2 classes or more. For the 25 mm mitral prostheses, the figures were 91% and 38% respectively. The peak rate of increase of left ventricular dimension in diastole (dD/dt) was measured echocardiographically in subjects with normal native mitral valves and in patients with 29 or 31 mm Medtronic-Hall valves, Björk-Shiley valves and Starr-Edwards valves. Peak dD/dt in the native valves was 15.8 +/- 0.8, in Medtronic-Hall valves 13.9 +/- 0.8, in Björk-Shiley 11.6 +/- 1.0 and in Starr-Edwards 9.5 +/- 0.6. The Björk-Shiley and Starr-Edwards valves differed significantly from normal (p less than 0.05 and less than 0.001 respectively) but there was no significant difference between the Medtronic-Hall valves and the native ones. We conclude that the Medtronic Hall valve is a safe and hemodynamically effective valve in the mitral position.
We describe and discuss the M-mode echocardiographic features in 10 patients with infective endocarditis of the aortic valve requiring surgery. Operative findings and aortic valve histology were obtained in each case. Vegetations were visualized in six out of seven patients (86%) with proven vegetations while pre-existing aortic valve disease masked their echocardiographic recognition in one patient. Diastolic echoes indistinguishable from vegetations were recorded from the ragged edge of a perforated aortic cusp in one patient who at operation had no demonstrable vegetations. Left ventricular outflow tract (LVOT) echoes were seen in five patients. Non-vibrating LVOT echoes were identified as vegetations while rapidly vibrating LVOT echoes were recorded from a flail aortic cusp. Premature mitral valve closure (PMVC) was seen in five out of seven patients (70%) with a short (less than or equal to four month) history of severe aortic regurgitation. Subannular aneurysms were detected in three out of five patients (60%) with this complication. Increased septal and left ventricular posterior wall motion suggestive of severe aortic regurgitation was seen in each case. The detection of a flail aortic valve leaflet, PMVC and subannular aneurysms indicates the need for surgery. The demonstration of vegetations defines a further subgroup of patients who should be managed in a centre with facilities for cardiac surgery. Echocardiography obviated the need for pre-operative cardiac catheterization in nine out of 10 patients (90%).
The effect of timolol, a beta-adrenoceptor blocking drug on the clinical status, thyroid status and left ventricular function as measured by serial M-mode echocardiographic recordings was assessed in a double-blind randomised study in 18 hyperthyroid patients. A significant clinical improvement was documented after 2 weeks of timolol treatment compared with placebo. There was no evidence that timolol impaired peripheral monodeiodination of thyroxine (T4). There were significant increases in left ventricular fractional shortening (Fr. Sh.) and velocity of circumferential shortening (Vcf) as well as a significant decrease in the left ventricular systolic internal dimension (LVIDs) (all P less than 0.01) in the untreated thyrotoxic patients compared with a normal euthyroid control group. After timolol treatment (2/52) there were significant increases in LVIDs and LVIDd and a significant decrease in Vcf (all P less than 0.05). No further changes occurred after a further 2/52 treatment with carbimazole. The cardiac data suggest that both an augmented sympathetic drive and a direct effect of thyroid hormone on myocardial contractility are mediators of the haemodynamic changes in hyperthyroidism.
M-mode echocardiograms and systolic time intervals were recorded before and six weeks after stopping digoxin in 11 patients in sinus rhythm to see whether the inotropic effect of digoxin was maintained with long-term treatment. Significant changes indicating a reduction in inotropic state on stopping digoxin were observed in the group. Clinical deterioration occurred in only one patient, associated with evidence of initially impaired cardiac function rather than an atypical response to digoxin. This study provides evidence that chronic digoxin treatment does continue to exert a positive inotropic effect.
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Acute aortic regurgitation as a consequence of infective endocarditis developed in a young man after peritonitis. A large subvalvar aortic root aneurysm extending to the mitral valve annulus together with features of severe acute aortic regurgitation were shown by M-mode echocardiography. The echocardiographic findings were confirmed at operation when obliteration of the aneurysmal space and aortic valve replacement were performed. Postoperative echocardiography confirmed obliteration of the aneurysmal space.
Chronic aortic valve disease is often tolerated for a long period of time with little in the way of symptoms, but once symptoms develop, the downhill course is often rapid. Medical therapy may alleviate symptoms of congestive heart failure and angina, but does not alter the natural history of the disease. The recent advances of cardiac surgery have, however, considerably improved the prognosis of most patients. Some patients with aortic regurgitation, though, will develop progressive congestive heart failure despite aortic valve replacement. Others with severe aortic stenosis will die suddenly while awaiting surgery as will a small number who previously had been asymptomatic. The information that comes from cardiac catheterization as well as the non-invasive investigation of cardiological disease, greatly enhanced by the introduction of the echocardiogram, has provided the physician with a better understanding of the particular problems in question and, therefore, the potential to solve them. This article aims to review the means by which high-risk groups can be identified, in order that their outlook may be improved especially with respect to the timing of surgical intervention.
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The echophonocardiographic features in three patients with a mitral Björk-Shiley prosthesis and paravalvular regurgitation are presented. The characteristic features are an early diastolic humping of the Björk-Shiley disc echo, associated with normal rather than paradoxical septal motion, and a reduced A2-MVO interval. The diagnosis was confirmed at operation in one patient, at cardiac catheterisation and operation in the second, and at necropsy in the third. These features were abolished by surgical correction of the leak in both operated cases.
The rate of decline of digoxin level in myocardium was estimated from operative samples of atrial and ventricular tissue from 40 patients undergoing cardiac surgery 1-20 days after maintenance digoxin treatment was stopped. Linear regression of myocardial log concentration-time curves for the group as a whole gave half-lives of 2.9 and 3.1 days in ventricular and atrial myocardium, respectively. Serum concentrations of digoxin were measured twice in each patient in this study: once while receiving treatment and once at the time of operation. Analysis of the 22 pairs of serum samples in which the second sample contained measurable levels of digoxin gave an estimated half-life of 2.3 days. The serum half-life was shorter than either the ventricular or the atrial myocardial half-life when data were analysed by unpaired statistics. Considering data only from those patients in whom the serum half-life was measured, to allow comparison by paired statistics, estimated ventricular and atrial half-lives were 1.5 and 1.3 days, respectively, which are significantly less than the respective serum half-lives of 2.3 and 2.1 days. Relatively slow clearance of digoxin from myocardium received further, anecdotal support from its demonstration in one patient 20 days after treatment was stopped.
We describe the case of an asymptomatic patient with primary hyperaldosteronism, who was diagnosed fortuitously following the demonstration of a positive Trousseau's sign during routine blood pressure assessment. Further investigations revealed that the carpal spasm was due solely to the associated profound hypokalaemia.