Semiquantitative classification of ductus venosus blood flow patterns

OBJECTIVES

To identify the range of waveform abnormalities in the ductus venosus (DV) characterized by their timing in the cardiac cycle and to evaluate if they can be categorized into distinct patterns.

METHODS

DV velocity ratios were calculated from peak velocities during ventricular systole (S), end-systolic ventricular relaxation (v), early diastole (D) and atrial systole (a) (S/v, S/D, v/D, S/a, v/a and D/a ratios). The ratios were converted to their Z-scores and elevation > 2 SD was assigned as abnormal. Combinations of ratio abnormalities were grouped to define distinct waveform patterns and their distribution was related to the clinical presentation.

RESULTS

Five-hundred and forty-two abnormal DV waveforms fell into three principal patterns. In Pattern 1 only the a-wave-related ratios were abnormal (180, 33.2%), in Pattern 2 the v/D ratio was abnormal (143, 26.3%) and in Pattern 3 combinations of a-wave abnormalities in the presence of a normal v/D ratio were normal (94, 17.3%).

CONCLUSIONS

Interpretation of venous waveform patterns is complex because the multiphasic waveforms reflect events in the cardiac cycle that may be differentially affected by clinical pathology. We sought to present a classification for the DV flow profile that characterizes abnormal flow confined to atrial systole and occurs during ventricular relaxation or during holodiastole. Further research is warranted to determine the significance of these patterns in specific fetal conditions.

Rene Theophile Hyacinthe Laënnec (1781-1826): the man behind the stethoscope

Rene Theophile Hyacinthe Laënnec (1781-1826) was a French physician who, in 1816, invented the stethoscope. Using this new instrument, he investigated the sounds made by the heart and lungs and determined that his diagnoses were supported by the observations made during autopsies. Laënnec later published the first seminal work on the use of listening to body sounds, De L'auscultation Mediate (On Mediate Auscultation). Laënnec is considered the father of clinical auscultation and wrote the first descriptions of bronchiectasis and cirrhosis and also classified pulmonary conditions such as pneumonia, bronchiectasis, pleurisy, emphysema, pneumothorax, phthisis and other lung diseases from the sounds he heard with his invention. Laënnec perfected the art of physical examination of the chest and introduced many clinical terms still used today.