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Blood pressure in the finger was measured by a servo-plethysmomanometer constructed after the design of Penàz, which uses the principle of the unloaded arterial wall. The device contains a photoelectric plethysmograph mounted in an inflatable cuff and an electro-pneumatic transducer to control air pressure in the cuff via a servosystem. Comparison of simultaneous measurements of intra-arterial pressure in the brachial artery was performed on 33 patients suspected of having hypertension. In 12 patients evaluation of the technique could not be carried out due to technical failures or distorted blood pressure wave forms. Results of the remaining 21 patients show a mean underestimation of intra-arterial blood pressure by finger cuff blood pressure of 0.8 kPa (6 mm Hg), both for systolic and diastolic levels. The scatter range of the difference is from 1.9 to -3.5 kPa for systolic and 0.1 to -2.5 kPa for diastolic values. It appears that, although not all technical problems are solved, the Penàz servo-plethysmo-manometer is potentially an elegant method by which to arrive at the fully calibrated wave form of blood pressure in a finger in a non-invasive and continuous fashion.

SUMMARY This study describes the newly discovered relation between ejection fraction and endsystolic volume index (ESVI) of the left ventricle as obtained by angiography at the time of cardiac catheterisation. Linear regression analysis shows that ejection fraction (%)=82 0-0 62 ESVI (ml/m2) but the correlation for patients receiving beta-adrenergic blocking drugs is significantly lower compared with the untreated group. Non-linear analysis, applied to cover also the asymptotic range for ejection fraction <20%, shows similar results. The good relation between the two indices indicates that the index ejection fraction may derive its clinical importance directly from the more fundamental index end-systolic volume index by virtue ofthe operation ofthe beta-adrenergic system on the heart. Generally, ejection fraction has been accepted clinically as a useful index to assess ventricular performance.I To date, no basis other than empirical observations has been provided on which the importance2 of ejection fraction is founded. Moreover, some investigators have questioned seriously the relevance of ejection fraction as a unique discriminator ofventricular performance.34 End-diastolic volume index (EDVI) has been regarded as a primary determinant of ventricular function, mainly in conjunction with the Frank-Starling law of the heart. Several studies have shown a more or less hyperbolic relation between ejection fraction and enddiastolic volume index.5-7 Recently, however, considerable attention has been given to systolic events during the cardiac cycle, and particularly to the endsystolic volume index89 and related quantities such as systolic elastance. [10][11][12] Since end-systolic volume is the volume to which the heart is able to contract under given conditions of preload and afterload this index is just as fundamental as end-diastolic volume to judge cardiac performance. Consequently, it seems logical to investigate the relation between the two systolic indices, ejection fraction and end-systolic volume index (ESVI). The present study documents a remarkable relation between the empirical index ejection fraction and the functional variable end-systolic volume index in a large group of patients. In addition, the effect of adrenergic blockade on this relation is studied by way ofanalysis ofa separate group ofpatients under chronic treatment with beta-blockade.Received for publication 12 November 1980 17 Patients and methodsThe population under consideration consisted of 165 unselected patients having angina and admitted to our clinic for medical examination. Their suitability for coronary bypass surgery was evaluated by selective angiocardiography, employing the Judkins technique. Fifty-two patients were not receiving any sympatholytic medication, while all the others (113) continued to receive their usual doses of beta-adrenergic blocking agents during the period of diagnostic catheterisation. Left ventricular cavity volume was determined angiographically using the right anterior oblique projection and the area-le...

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