External jugular phlebogram as reflecting venous and right atrial hemodynamics

The usefulness, reproducibility and reliability of the jugular phlebogram recorded from the external body surface in reflecting the hemodynamic events of the right side of the heart were studied in various ways: (1) Simultaneous right atrial pressure and external venous jugular phlebograms demonstrate that the curves are qualitatively similar. The a and v wave peaks are similar in form with a constant time-lag of the phlebogram in the normal patient of 0.02 sec. (2) Effect of respiration: In addition to a marked decrease in the relative amplitudes of all waves with expiration, various interrelationships between the waves are altered. (3) Position changes: the degree to which the upper body is elevated above the horizontal, changes in the position of the probe and the degree of neck rotation were correlated with changes in the slopes, relative amplitudes and peak-to-peak intervals of the curves. (4) Pathologic conditions: recordings from patients with proved heart lesions accurately reflected altered hemodynamics; in particular, the absence of either the venous systolic or diastolic collapse in patients with dominant mitral insufficiency showed various hemodynamic effects on the right heart which can obtain. (5) Cardiac arrhythmias: consistent changes in phlebograms produced by heart block, and disturbances of rhythm where the pacemaker is not in the sinoatrial node accurately reflected circulatory changes. The various changes observed in these studies are explained in terms of the physiology of the venous return to the heart and suggest a new hypothesis for the generation of the c wave.