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Many workers have shown that the cardiac output in normal man is less in the upright than in the recumbent position (McMichael and SharpeySchafer, 1944;Stead et al., 1945;Coe, Best, and Lawson, 1950;Wang, Marshall, and Shepherd, 1960;Chapman, Fisher, and Sproule, 1960;Reeves et al., 1961). The physiological events underlying this change are complex and depend on many variables, such as the angle of tilt and length of time the patient remains at a given angle and whether the change is from recumbency to an upright position or vice versa. Posture and its relation to cardiac output here becomes increasingly important with the introduction of hypotensive drugs. The purpose of this study was to determine the relation ofthe angle oftilting to the changes in cardiac output, blood pressure, and pulse rate in normal man. SUBJECTS AND METHODS Studies were carried out on 33 subjects: 28 women and 5 men, whose average age was 37 years.The observations were all made three hours after breakfast or lunch. The relative cardiac outputs were measured by the indicator dilution method from dye curves recorded by a photoelectric earpiece (Gabe, Tuckman, and Shillingford, 1962), chopper amplifier, and direct writer recording system. All subjects rested quietly in the supine position for 30 minutes before the first cardiac output determination. Coomassie blue dye was injected from a calibrated syringe through a three-way tap and eighteen-gauge needle into an antecubital vein, a 5 per cent dextrose-in-water drip keeping the system open between injections. In any one subject the injections of dye were of equal quantity and varied from 20 to 30 mg./injection in different subjects.

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Oxygen is frequently given in the treatment of patients with acute myocardial infarction. The hemodynamic changes associated with its administration in this condition have not been defined.The purpose of this study has been to investigate the effect of breathing oxygen on the cardiac output and systemic arterial pressure of patients in the early stages of acute myocardial infarction. SUBJECTS AND METHODSSix male patients aged 47 to 72 years were studied on the first and second day of myocardial infarction.In two of these there were additional studies on the sixth and seventh days. In one patient there was only one study on the tenth day. All had unequivocal evidence of acute myocardial infarction as judged by the clinical history and electrocardiograph. The clinical data are given in Table I.All patients were investigated in a special intensive care unit permanently equipped with apparatus for observation, investigation, and treatment of patients with acute myocardial infarction (Shillingford and Thomas, 1964). Facilities were available for the measurement of cardiac output and intravascular pressures.After clinical assessment, electrocardiography, and chest radiography were completed, polythene catheters (Intramedic U.S.A. PE60) were inserted percutaneously into the brachial artery and an antecubital vein. The venous catheter was advanced so that the tip lay in the superior vena cava. Heart rates were measured from an electrocardiographic tracing over half-minute periods throughout the study and when cardiac output determinations were made. Cardiac output was measured by a dye dilution technique using Coomassie Blue (I.C.I.) as indicator and recording the curve with a photoelectric earpiece (Cambridge Instrument Co.).The first curve was calibrated by equating the height of the tail of the curve three minutes after injection with the amount of indicator in a central venous or arterial blood sample taken at the same time. Dye was extracted from the plasma and measured by spectrophotometry. Subsequent cardiac outputs were calculated according to the areas of the curves (Gabe, Tuckman, and Shillingford, 1962

A direct hemodynamic assessment of cardiac function in man is a desirable addition to a clinical appraisal of the cardiovascular system. Cardiac performance, however, involves many factors and while it is possible to analyse some of these in animal experiments, extensive investigations are not usually admissible in patients with ischmmic heart disease.McMichael and Sharpey-Schafer (1944) showed in normal subjects that by changing the posture from the upright to recumbent position the cardiac output and stroke volume were raised. These observations have been used as a basis for a test of myocardial function in which changes of cardiac output are measured by dye dilution and the photoelectric earpiece technique.The purpose of this paper is to describe such a test, to give the results when applied to normal subjects and to patients with ischaemic heart disease, and to discuss their significance in relation to the clinical findings. SUBJECTS AND METHODSStudies were carried out on 26 patients; 18 of these had suffered a myocardial infarction and 8 had no evidence of cardiovascular or debilitating disease. The ages are shown in the Table; with one exception those of the controls are comparable with those of the patients with ischoemic disease.In most cases the ischemic patients were convalescent following myocardial infarction and were undertaking only minor activities. In these, the investigation was made between two and six weeks after the acute episode. Two patients had recovered from infarction several months previously.Of the patients with ischoemic heart disease, 11 had been in cardiac failure previously, but at the time of the investigation only 6 had clinical evidence of failure; 7 were receiving treatment with digitalis with or without a diuretic. The patients were in sinus rhythm.A routine clinical examination, chest radiograph, and electrocardiogram were carried out in all patients. The diagnosis of myocardial infarction was accepted on the basis of a typical history and electrocardiographic abnormality.Two estimations of the cardiac output, pulse rate, and blood pressure were made with the patient resting quietly in a twenty degree feet down position on a tipping table. The position was then changed to the horizontal and the legs were raised to sixty degrees by means of a wooden support (Fig. IA and B). Two further measurements of cardiac output, pulse rate, and blood pressure were then made at three-minute intervals, the first of these being made three minutes after the change of posture. Cardiac output was estimated by an indicator dilution technique (Taylor and Shillingford, 1959;Thomas, Malmcrona, and Shillingford, 1964) using the photoelectric earpiece.* A known quantity (50 mg.) of Coomassie Blue dye was injected from a special syringe through a fine polythene cathetert inserted through a needle in the median antecubital vein and advanced into the great veins. The resultant dye dilution curve was calibrated in terms * Cambridge Instrument Co.

A method of surface mapping of the RS-T segment deviations that occur in acute myocardial infarction is described. The results observed in i5 patients are recorded and the potential value of this procedure is discussed in (i) diagnosis of myocardial infarction; (ii) delineating the extent of the myocardial ischaemia; and particularly (iii) its use as a method of examining the effect of therapies on the extent of myocardial ischaemia.Body surface iso-potential maps of the QRS have been reported in normal adults (Taccardi, I963), children (Spach et al., I966), and infants (Tazawa and Yoshimoto, I969), and in a number of cardiac disorders (Blumenschein et al., I968; Karsh, Spach, and Barr, I970). In experimental myocardial infarction in dogs, the area of the RS-T segment deviation in the epicardial leads has been used to represent the area of ischaemic myocardium (Rakita et al., 1954; Katcher, Peirce, and Sayen, I960; Sayen et al., I958; Braunwald et al., I969). It seemed probable that in man surface mapping of the RS-T segment deviations on the chest wall would reflect in some measure the underlying epicardial changes and perhaps define the position and extent of the myocardial infarction to a greater degree than the routine electrocardiogram.It is the purpose of this paper to describe a method and give the results of surface mapping of the RS-T segment deviations that were observed in a series of cases of proven myocardial infarction. MethodsFifteen patients who were admitted to the coronary care unit in the Hammersmith Hospital with a clinical diagnosis of acute myocardial infarction were studied. All but one had electrocardiographic evidence of acute myocardial infarction on the standard I4 lead electrocardiogram (including V4R and V7) and all had a transient diagnostic rise in serum enzymes.Electrocardiograms were recorded using a direct writing ink jet apparatus (Mingograph Elema-Schonander) recording on the three channels simultaneously. The electrodes used were the Welsh self-retained type with a contact diameter of i cm. In order to avoid spread of potentials the electrode jelly was applied only over a small area and the electrodes were carefully separated. The gain employed was I0 mm for I m volt and the paper speed was 25 mm/sec.The praecordial electrocardiograms used for surface mapping were recorded with the patient in the supine position and recorded daily for the first 7 days after the onset of symptoms and subsequently every few days during the patient's stay in hospital. In a few patients further electrocardiograms were recorded from 2 to 7 weeks later. These electrocardiograms were recorded from 72 points, distributed evenly throughout an area which extended from the mid-clavicular line on the right to the mid-axillary line on the left and from a line drawn horizontally through the angle of Louis to a line drawn horizontally through a point 6 cm below the xiphisternum (Fig. I). These points, which were 3 to 4 cm apart, were marked with a skin pencil so that all subsequent electrocardiograms were...