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Biomedical subjects

J Ross

Publications and source records attributed to J Ross.

At least 559 records · Page 31Linked to original sources
PubMed1984

Usefulness of the chest x-ray for predicting abnormal left ventricular function after acute myocardial infarction.

We evaluated 229 patients discharged after a definite acute myocardial infarction. Pulmonary venous congestion determined from chest x-ray films during the hospitalization and at discharge and the cardiothoracic ratio at discharge were compared to the left ventricular ejection fraction measured at discharge by a gated radionuclide technique. During hospitalization, pulmonary venous congestion was found on at least one x-ray frame in 94 patients (41%). At discharge 134 patients (59%) had abnormal ejection fraction (less than 0.51) and 35 had pulmonary venous congestion (15%). The sensitivity of the x-ray for detecting an abnormal ejection fraction was 20% when pulmonary venous congestion was observed on the discharge x-ray film (specificity 92% and predictive value 77%), 52% if pulmonary venous congestion was present on any x-ray film during the hospitalization (specificity 74% and predictive value 73%), and 47% if the cardiothoracic ratio was abnormal (greater than or equal to 0.50) on the discharge x-ray film (specificity and predictive value 66%). We conclude that an abnormal x-ray film at discharge or during the hospitalization will identify approximately one-half of the abnormal ejection fractions at the time of hospital discharge. Therefore, to reliably assess left ventricular function, either for prognostic or therapeutic purposes in the individual patient, a more direct measure of left ventricular function such as radionuclide angiography must be obtained.

Adult↗
PubMed1984

Calcification of the tricuspid anulus diagnosed by two-dimensional echocardiography.

An 84-year-old female who previously underwent repair of an atrial septal defect had evidence of increased reflectiveness of the posterior tricuspid anulus in the apical four-chamber view and the right ventricular two-chamber view. In addition, the inferior vena cava was dilated and during contrast echocardiography, contrast echoes appeared during systole suggesting tricuspid regurgitation. Tricuspid annular calcification was confirmed by fluoroscopic examination. Tricuspid annular calcification is extremely rare and in the present series occurred in 1 of 80 patients with mitral annular calcification. Lateral resolution echoes from a calcified aortic valve and echoes originating from a calcified right coronary artery have to be distinguished from tricuspid annular calcification.

Aged↗
PubMed1984

Clinical and echocardiographic correlations in right heart endocarditis.

UNLABELLED: The echocardiographic findings were correlated with the clinical findings and outcome in 23 patients with tricuspid valve or pulmonary valve endocarditis. There were 15 males and 8 females with a mean age of 33.1 +/- 8.4 years. Eighteen patients had tricuspid valve endocarditis, 1 patient had pulmonary valve endocarditis, 3 patients had concomitant mitral valve and tricuspid valve endocarditis, and 1 patient had tricuspid valve and pulmonary valve endocarditis. Twenty of the 23 (87%) patients had a history of intravenous drug abuse. The most common organisms were Staphylococcus aureus (10 of 23 patients or 43%), Streptococcus viridans (5 patients) and Pseudomonas aeruginosa (4 patients). Pulmonary manifestations with septic pulmonary emboli were present in 18/23 (80%) patients, and a regurgitant murmur in 16/23 (73%) patients. Vegetations on the tricuspid valve or pulmonary valve were detected in all patients who had 2D echo, but they were missed by M-mode echo in 2 patients. Nine of the 23 patients (40%) improved on medical therapy, 5 (21%) expired, and 7 (30%) required surgery (tricuspid valve or pulmonary valve replacement in 3, and tricuspid valve excision without replacement in 4). CONCLUSIONS: (1) 11 of 13 patients with persistent infection, multivalvular involvement, fungal or Pseudomonas infection and increasing size of vegetations by echo died or underwent surgery compared to only 1 of 8 patients without these features (P less than 0.01). (2) Staphylococcus aureus infection (10 patients) and flail tricuspid valve or pulmonary valve by echo (6 patients) were not predictive of outcome.

Adult↗
PubMed1984

Free perichondrial graft from the ear to the knee in rabbits.

Perichondrial grafts used in arthroplasties have been placed routinely with the cartilage-producing surface facing the joint space. Our study evaluates whether the orientation of the cartilage-producing surface of the perichondrial graft toward or away from the eburnated bone had any effect on the graft pattern 8 weeks after surgery. Fourteen rabbits were studied. The cartilage of both lower limb patellae was removed in all rabbits. The eburnated surfaces of 12 rabbits received perichondrial grafts from the ear, cartilage-producing side facing the joint space in one limb and cartilage-producing surface facing the bone in the other. Two rabbits that received no perichondrial grafts were also studied. After 8 weeks, the animals were killed and the patellar surfaces evaluated by gross and histologic studies. We observed that graft orientation made no difference in the histologic appearance or the thickness of the neocartilage formed.

Animals↗
PubMed1984

Clinical and echocardiographic evaluation of the St. Jude cardiac valve prosthesis: follow-up of 126 patients.

One hundred twenty-six patients with a St. Jude valve prosthesis were followed up clinically and studied by combined M-mode echocardiography and phonocardiography. Fifty patients underwent aortic valve replacement, 58 underwent mitral valve replacement and 18 underwent a combination of the two. The early postoperative mortality rate was 8% for aortic, 6.9% for mitral and 6% for combined valve replacement. Follow-up ranged from 2 to 46 months (mean +/- SD 28 +/- 9). The late postoperative mortality rate was 5%; in patients who survived, improvement in New York Heart Association functional class occurred in 97%. Major thromboembolic events occurred in two patients and anticoagulation-related complications occurred in three patients. Valve-related complications occurred in 14 patients and included bacterial endocarditis (6 patients), paravalvular leak (5 patients), severe hemolysis (1 patient), thrombosis of valve (1 patient) and possible mechanical valve failure (1 patient). In 7 of these 14 patients, repeat surgery was required and 5 patients survived. Abnormal echocardiographic findings in these seven patients included a shortened aortic closure (A2) to mitral valve opening interval, increased left atrial and left ventricular size and initial diastolic rounding of the St. Jude valve motion in the patient with the thrombosed valve. It is concluded that the St. Jude valve prosthesis is associated with favorable functional results and a low complication rate for a mean follow-up period of 28 months. Combined M-mode echocardiography and phonocardiography may be useful in assessing patients with suspected complications related to the St. Jude cardiac valve.

Adult↗
PubMed1984

Development and regression of left ventricular hypertrophy.

Left ventricular hypertrophy is an important adaptive response to chronic pressure or volume overload of the left ventricle. The different types and the pathophysiologic mechanisms of the development of left ventricular hypertrophy in various disease states are reviewed. Detection of left ventricular hypertrophy may be accomplished by electrocardiography and cardiac angiography. Echocardiography, however, is the most accurate noninvasive method to detect the presence and estimate the severity of increased left ventricular mass. The clinical significance of left ventricular hypertrophy and its prognostic implications in several cardiac diseases associated with hypertrophy are discussed. The critical transition stage from adaptive, compensatory and reversible left ventricular hypertrophy to "pathologic" hypertrophy with impaired left ventricular contractility and irreversible myocardial damage is yet unknown. Recent data are presented that provide evidence of regression of left ventricular hypertrophy after medical treatment of patients with hypertension and after aortic valve replacement in patients with aortic valve disease. The clinical importance of regression of hypertrophy and its effects on long-term prognosis remain to be determined.

Animals↗
PubMed1984

Prognostic importance of digitalis after acute myocardial infarction.

Because previous reports have suggested that digitalis administration may lead to increased mortality after hospital discharge for acute myocardial infarction, the independent importance of digitalis therapy in long-term prognosis after acute myocardial infarction was investigated by analyzing 1,599 patients after definite myocardial infarction. After hospital discharge, mortality rate for the entire group at 4 months was 7.7% and after 1 year 14.2%. At discharge, 36.6% of the patients were taking digitalis. Compared with those not taking digitalis, those taking digitalis had more historical risk factors and a higher incidence of important clinical prognostic variables during the hospitalization. Their cardiac mortality rate after 4 months and 1 year (12.5 and 22.4%, respectively) was significantly higher than that of patients not taking digitalis (5.0 and 9.6%, respectively). Mortality was higher for patients taking digitalis whether or not they had congestive heart failure during hospitalization. However, in a multivariate Cox analysis for 1 year outcome, neither digitalis nor any other medication variable displaced the important clinical variables of age, congestive heart failure during the hospitalization, previous myocardial infarction, maximal heart rate during the hospitalization and previous angina. Quinidine and digitalis at discharge were selected sixth and seventh (not significant) by the analysis. It is concluded that digitalis therapy at discharge after myocardial infarction was not an independent predictor of late mortality in these patients.

Aged↗
PubMed1984

Correlation among right ventricular preload, afterload and ejection fraction in mitral valve disease: radionuclide, echocardiographic and hemodynamic evaluation.

The relation among right ventricular preload, afterload and ejection fraction in patients with mitral valve disease has not been well elucidated. In this study, measurements were made of intracardiac pressures and forward cardiac output during cardiac catheterization (n = 43), the ejection fraction by radionuclide angiography (n = 43) and end-systolic radius and wall thickness by M-mode echocardiography (n = 22). There was a linear correlation between pulmonary artery pressure and right atrial pressure (r = 0.57, p less than 0.01). The right ventricular peak circumferential systolic wall stress was increased in 68% of the patients (in comparison with wall stress measurements obtained in 10 normal subjects). The right ventricular ejection fraction was abnormal in 38 patients (88%) and abnormal in 14 of the 15 patients with high wall stress. There was an inverse correlation between ejection fraction and end-diastolic volume (r = -0.61, p less than 0.001). The right ventricular ejection fraction measurement was repeated within 3 months after mitral valve replacement in 16 patients; the ejection fraction increased from 21 +/- 9 to 29 +/- 10% (mean +/- standard deviation) after surgery (p less than 0.01), but normalization of the ejection fraction was observed in only 3 patients (19%). Thus, abnormal right ventricular ejection fraction, which is observed in most patients with rheumatic mitral valve disease, results from inappropriate wall stress or depressed inotropic response of the right ventricle due to damage. Right ventricular dilation appears to be a compensatory mechanism to maintain the cardiac output.

Aged↗
PubMed1984

Tricuspid regurgitation: noninvasive techniques for determining causes and severity.

Tricuspid regurgitation is often not apparent on physical examination and several methods are now available to aid in this difficult assessment. Cardiac catheterization using right ventriculography, previously considered the diagnostic standard, has several limitations. Currently available noninvasive tools such as M-mode and two-dimensional echocardiography (with or without contrast), Doppler techniques and even radionuclide cardiologic imaging have added significantly to the precise assessment of the presence and severity of tricuspid regurgitation. This review examines the comparative use and limitations of these various techniques.

Animals↗
PubMed1984

The development of genetic resistance to myxomatosis in wild rabbits in Britain.

The presence of genetic resistance to myxomatosis in a sample of wild rabbits from one area in England was reported in 1977. Rabbits from three other areas in Great Britain have been tested subsequently, and all cases showed similar resistance to a moderately virulent strain of myxoma virus. Rabbits from one area also showed a significant degree of resistance to a fully virulent strain of virus. It is concluded that genetic resistance to myxomatosis is widespread in wild rabbit populations in Britain. The implications of the results are discussed in relation to the co-evolution of the disease and its host.

Animals↗
PubMed1984

alpha-Amanitin-insensitive transcription of mouse beta major-globin 5'-flanking and structural gene sequences correlates with mRNA expression.

A small proportion of the RNAs of mouse reticulocytes consists of beta major-globin mRNA sequences linked to sequences transcribed from the 5'-flanking region of the beta major-globin gene. These upstream RNAs are polyadenylylated and contain 700-800 nucleotides, and their 5' regions are heterogeneous. RNAs with similar or identical 5' regions are transcribed in cell-free extracts from a circular mouse beta major-globin gene template. Synthesis of most of the upstream RNAs in vitro is not inhibited by low levels (1 microgram/ml) of alpha-amanitin, indicating that they are transcribed by an enzyme(s) different from RNA polymerase II. During culture of mouse erythroleukemia cells with dimethyl sulfoxide, globin mRNA and upstream RNAs accumulate with similar kinetics. In contrast, upstream RNAs are not detected in hemin-treated cells.

Amanitins↗
PubMed1984

Effect of decreased renal function on the pharmacokinetics of ceftazidime.

The pharmacokinetics of ceftazidime after a 1-g bolus dose were studied in 11 subjects, with creatinine clearances ranging from 113 to 6 ml/min. Concentrations of ceftazidime in serum were determined by microbiological assay. These data were fitted to a two-compartment open model, and pharmacokinetic parameters were calculated. Correlation of ceftazidime clearance with creatinine clearance was excellent (r = 0.99).

Adult↗
PubMed1984

Comparison of echocardiography and angiography in determining the cause of severe aortic regurgitation.

To assess the accuracy of echocardiography in determining the cause of aortic regurgitation M mode and cross sectional echocardiography were compared with angiography in 43 patients with predominant aortic regurgitation. Each patient had all three investigations performed during the same admission to hospital. In each instance, the cause of aortic regurgitation was confirmed at surgery or necropsy. Seventeen patients had rheumatic aortic valve disease, 13 bacterial endocarditis with a perforated or partially destroyed cusp, five a bicuspid aortic valve (four with a history of endocarditis), and eight aortic regurgitation secondary to aortic root dilatation or aneurysm. Overall sensitivity of echocardiography and aortography was 84% in determining the cause of aortic regurgitation. Thus, rheumatic valve disease and endocarditis appear to be the most common causes of severe aortic regurgitation in this hospital based population. Furthermore, echocardiography is a sensitive non-invasive technique for determining the cause of aortic regurgitation and allows differentiation of valvular from root causes of aortic regurgitation.

Adult↗
PubMed1984

Effects of beta-blockade on regional myocardial flow and function during exercise.

We examined the effects of a cardioselective beta-blocking drug on exercise-induced regional myocardial ischemia in 10 conscious dogs with chronic coronary artery stenosis. An ameroid constrictor, Doppler flowprobe, and hydraulic cuff were placed around the left circumflex coronary artery, and left ventricular pressure (LVP), systolic wall thickening (% delta WT; by sonomicrometry), and myocardial blood flow (MBF; microspheres) were measured during control standing, control treadmill exercise, and identical exercise after atenolol (1 mg/kg po). Prior to study, in every dog % delta WT and MBF in the ischemic area were normal at rest, indicating collateral development. During control exercise, % delta WT in the ischemic region markedly decreased from 27 to 4%, and transmural ischemia was evident in that region. Heart rate, systolic LVP, and LV (+)dP/dt were significantly lower during exercise after atenolol than during control exercise. % delta WT in the normal area was only 81% of that during control exercise, but dysfunction in the ischemic area was improved (77% increase compared with control exercise). Accompanying the improved function was a significant increase of MBF/beat and relative MBF in the ischemic zone; the endocardial-to-epicardial ratio increased from 0.27 to 0.47. Thus atenolol improved regional MBF distribution, thereby diminishing exercise-induced regional myocardial dysfunction and accelerating its recovery.

Adrenergic beta-Antagonists↗