Background and Goal of Study:

In echocardiography, a pulmonary embolism is characterized by a D-shaping of the left ventricle. The specificity of

this characteristic has recently been challenged, as hypoxia induced by acute asphyxia resulted in D-shaping of the

left ventricle. However, decompensation of respiratory distress most often manifests as progressive hypoventilation.

Therefore, we aimed to evaluate the left ventricular ultrasonographic appearance of progressive hypoventilation using

a porcine model. 

We hypothesized that progressive hypoventilation would lead to a gradual D-shaping of the left ventricle.

Materials and Methods:

The Danish Inspectorate of Animal Experimentation approved the study (authorization number: 2013-15- 2934-

00765). Fifteen piglets (intervention n=10 control n=5) were included in the study. The intervention piglets underwent

three ten-minute periods of graded hypoventilation before respiratory resuscitation was initiated. Parasternal short

axis view cineloops were stored and arterial blood samples were drawn after 3, 6 and 9 minutes at each level of

hypoventilation. During resuscitation, cineloops were stored every minute and arterial blood samples drawn every

second minute.

Results and Discussion:

Left ventricular eccentricity index (LV-EI), an ultrasonographic index of D-shaping, increased from 1.1 (1.0-1.1) at

baseline to 1.4 (1.3-1.4) three minutes into the final intervention (P&lt; 0.001). After two minutes of respiratory

resuscitation LV-EI returned to baseline (1.1 (1.1-1.2), P=0.093) and stayed at this level (P=0.348).

Progressive hypoventilations yields a reversible echocardiographic image, which to many clinicians is synonymous

with pulmonary embolism.This questions signs of right ventricular overload as a specific rule-in diagnostic, and may

make repeated echocardiography after reoxygenation an important differential diagnostic tool.

Conclusion(s):

Progressive hypoventilation caused reversible D-shaping of the left ventricle and poses a differential diagnosis to

pulmonary embolism.

Progressive hypoxia causes reversible left ventricular D-shaping in an experimental porcine model