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Biomedical subjects

E L Fallen

Publications and source records attributed to E L Fallen.

54 records · Page 3Linked to original sources

Effect of encouragement on walking test performance.

Walking tests, frequently used to document effects of treatment on exercise capacity, have never been standardised. We studied the effects of encouragement on walking test performance in a randomised study that controlled for the nature of the underlying disease, time of day, and order effects. We randomised 43 patients with chronic airflow limitation or chronic heart failure or both to receive or not receive encouragement as they performed serial two and six minute walks every fortnight for 10 weeks. Simple encouragement improved performance (p less than 0.02 for the six minute walk), and the magnitude of the effect was similar to that reported for patients in studies purporting to show beneficial effects of therapeutic manoeuvres. Age and test repetition also affected performance. These results demonstrate the need for careful standardisation of the performance of walking tests, and suggest caution in interpreting studies in which standardisation is not a major feature of the study design.

Chronic Disease↗

Pulmonary veno-occlusive disease: antemortem diagnosis from roentgenographic and hemodynamic findings.

A 17-year-old boy with pulmonary veno-occlusive disease underwent Swan--Ganz catheterization. A normal pulmonary capillary wedge pressure was recorded in the presence of severe pulmonary arterial hypertension and roentgenographic evidence of pulmonary venous congestion. This triad of findings permitted an unequivocal diagnosis of pulmonary veno-occlusive disease, which was later confirmed at autopsy. The hemodynamics of this condition and of others included in the differential diagnosis are presented schematically.

Adolescent↗

Afterload as a predeterminant of haemodynamics and segmental wall motion following coronary artery occlusion.

Maximal changes in haemodynamics and segmental wall motion were seen 2 min after coronary occlusion and were examined in relation to the loading conditions of the left ventricle before occlusion in 20 open chest dogs. There was a significant inverse relationship between the preligation mean aortic pressure and the percentage decrease in stroke volume following ligation. This relationship was observed whether afterload was distributed randomly (mean aortic pressure ranging from 9.7 to 17.6 kPa [73 to 132 mmHg]) between all dogs (r = 0.65; P less than 0.001) or altered by methoxamine (+4 kPa [+30 mmHg]) and nitroprusside (-3.2 kPa [-24 mmHg]) within the same dog (r = 0.82; P less than 0.001; n = 8). Although occlusion of the anterior descending artery caused a small (+5.5%) but significant increase in end-diastolic length of the non-ischaemic epicardial segment, the capacity for compensatory ventricular dilatation was not dependent on preligation afterload. However, the capacity of the ischaemic segment to undergo systolic expansion was significantly greater (+30.2% of end-systolic segment length) in those dogs with the lowest preligation MAP (8 to 12 kPa [60 to 90 mmHg]) compared with systolic lengthening of only 15.8% in the high afterload group (15 to 18 kPa [112 to 135 mmHg]). These data indicate that the loading conditions of the left ventricle predetermine the extent of global and segmental left ventricular dysfunction during the early phase of acute ischaemic injury.

Animals↗

Relief of coronary artery spasm by nitroglycerin: time-dependent variability in drug action.

The arteriographic distinction between a fixed atheromatous obstruction and localized vasospasm in the coronary artery is often decided by the response of the lesion to nitroglycerin. We studied the time course of nitroglycerin in four patients with coronary artery spasm as revealed by selective angiography. Following complete dissolution of a 0.6 mg tablet of nitroglycerin sublingually a slight increase in heart rate occurred as early as two minutes, variable changes in overall vessel diameter were observed within four minutes, but the localized spasm remained fixed. It was not until six minutes had elasped that reinjection showed disappearance of spasm and uniform patency of the vessel in all cases. These observations stress the importance of waiting an appropriate period of time (at least six minutes) following complete absorption of sublingual nitroglycerin before any conclusion can be rationally drawn regarding the nature of a stenotic lesion as seen angiographically.

Adult↗

Myocardial infarction size from serial CPK: variability of CPK serum entry ratio with size and model of infarction.

To study the variability of the fraction of CPK released from the infarcted heart which enters the serum (serum entry ratio, or SER) with size and model of infarction, nine dogs underwent homogeneous infarctions (LAD ligation) of varying sizes, and 10 dogs underwent scattered infarctions (left coronary embolization). In homogeneous infarcts there was an inverse linear relationship of SER to infarct size (IS) (SER = -0.8514% LV + 0.345, r = 0.98). No such relationship was found for scattered infarcts. CPK Kd (exponential disappearance constant for CPK) was not significantly different in homogeneous (-0.00178 min-1) vs scattered infarcts (-0.00195 min-1). Although similar IS was produced in each (homogeneous 19.9% LV, scattered 18.4% LV) cumulative CPK serum entry (CPKr) was much lower in homogeneous (4175 mlU/ml) vs scattered infarcts (7,296 mlU/ml). SER was also much lower in homogeneous (17.7%) vs scattered infarcts (29.0%) (P less than 0.025). Cumulative CPK plateau occurred significantly later in homogeneous (15.8 hours) vs scattered infarcts (11.7 hours) (P less than 0.01). Further corrections to the serial CPK equations for IS determination are indicated. The method may not be applicable in some infarct situations, e.g., scattered infarction.

Animals↗

Differences between the effects of practolol and propranolol on the diastolic properties of the left ventricle.

To elucidate the mechanism by which left ventricular and diastolic pressure (LVEDP) is reduced by practolol, ventricular volumes, hemodynamics, and diastolic elastic stiffness were determined before and 10 min after intravenous practolol (400 mug/kg) in 12 patients. Heart rate decreased in all patients after practolol (avg., --9/min, p less than 0.02). There was an insignificant increase in stroke work index and decrease in cardiac index attributable to the fall in rate. Practolol did not change and diastolic volume or ejection fraction, but the average LVEDP fell from 21 to 15 mm Hg (p less than 0.01) which was sustained even with atrial pacing to prepractolol heart rates. Diastolic elastic stiffness was also reduced after practolol (0.665 to 0.593, p less than 0.0025). The data indicate that practolol exerts a negative chronotropic effect on the intact heart and, in contrast to other beta blockers such as propranolol, appears to decrease diastolic stiffness in the left ventricle.

Adult↗

Experience with bretylium tosylate by a hospital cardiac arrest team.

The effect of bretylium tosylate (BT) was determined in 27 consecutive cases of resistant ventricular fibrillation (VF) encountered by a hospital cardiac arrest team. The VF was sustained and completely resistant to multiple injections of lidocaine, sequential DC shocks at 400 watt-sec and one or a combination of intravenous propranolol, diphenylhydantoin or procainamide. Following 30 min of sustained cardiac massage, BT (5 mg/kg i.v.) was administered. In 20 patients, VF was terminated within 9-12 min after DC shock. Eight of these patients failed to recover while 12 (44%) of all patients resuscitated survived to be discharged from hospital. Eleven out of 20 (55%) of all patients who had a cardiac arrest outside the CCU were survivors; only one out of seven in the CCU were successfully resuscitated. While receiving maintanance BT post-resuscitation (5 mg/kg i.m. q 8-12 hrs x 48 hrs), half the patients developed hypotension and three required vasopressors and/or fluid replacement. The data indicate that BT is a useful agent in patients with sustained VF refractory to repeated lidocaine injections, some other antiarrhythmic agents, and multiple DC shocks.

Bretylium Compounds↗

Development and testing of a new measure of health status for clinical trials in heart failure.

The authors developed a new measure of subjective health status for patients with heart failure. Eighty-eight patients with heart failure were asked about the impact of their condition on 123 items related to physical and emotional function. The most frequently chosen and important items were included in a 16-item Chronic Heart Failure Questionnaire (CHQ) that examines dyspnea during daily activities, fatigue, and emotional function. The CHQ was tested in a controlled trial of digoxin in heart failure patients in sinus rhythm. When administered serially to 25 patients in the run-in phase of the trial, the CHQ proved reproducible. Subsequently, CHQ results distinguished those who reported improvement or deterioration from those who did not. The CHQ showed moderate correlations with patient global ratings, walk test scores, and clinical assessments of heart failure. The authors conclude that the CHQ may be useful for measuring health status in clinical trials in heart failure.

Aged↗