Transesophageal Echocardiographic Identification of Normal and Stenosed Posterior Intercostal Arteries

Common trunk of the posterior intercostal arteries from the thoracic aorta: anatomical variation, frequency, and importance in individuals

PURPOSE

A common trunk of the posterior intercostal arteries originating from the descending thoracic aorta is normally an anatomical variation. A search through the literature disclosed the frequencies of common trunks variations among population, but no information relates to particular topic of simultaneous multiple common trunks of the PIA present in individuals.

METHODS

A total of 396 intercostal spaces were dissected in 44 cadavers from the vertebral body to the mid-axillary line to observe a common trunk of the paired posterior intercostal artery at the level from T2 to T11 intercostal space.

RESULTS

In 31 cadavers (70%), a common trunk of posterior intercostal arteries arising from descending thoracic aorta was visualed and 22 of those (71%) had two or more common trunks simultaneously present.

CONCLUSIONS

It is important to recognize this anatomical variation when the number of origins of the posterior intercostal arteries from the thoracic aorta due to the multiple common trunk present can be reduced, as their origins and vascular territories are involved in primary diseases of the thoracic aorta, like atherosclerosis, aneurysm, or dissection that lead to serious complications. For example, in thoracoabdominal aneurysm repair, reimplantation of the posterior intercostal arteries is recommended to avoid potential ischemic injury to the supplying areas, especially to the spinal cord.

Factors influencing the diameter of human anterior and posterior intercostal arteries

At present, there have not been any detailed studies examining the size relationships of the intercostal arteries. This study was carried out to investigate the relationship between the vessel lumenal diameter of ipsilateral, paired anterior and posterior IC arteries, as well as with the length of the IC space supplied by each artery. Samples were collected from the second-sixth anterior and posterior IC arteries near their site of origin, and the lengths of the corresponding IC spaces were measured in 42 cadavers. Lumenal diameters of both the anterior and posterior IC arteries at consecutive IC space closely followed second degree polynomial regression models (R(2) = 0.9655, and R(2) = 0.9741, respectively), and reached maximum size at the fifth IC space, which was found to be the longest of the IC spaces. No direct relationship was observed between diameters of the paired anterior and posterior IC arteries, although there was a trend for the larger anterior IC arteries to be paired with the larger posterior IC arteries. The calculated rate of blood flow at each IC artery was approximately two-fold greater in males than in females. These results suggest that the length of the IC space, and hence the extent of the thoracic wall supplied, is a major factor in determining the diameter of both anterior and posterior IC arteries. Since COPD is such a prevalent disease, this study also examined its influence on the IC arteries, and found that the posterior IC arteries are significantly larger among afflicted subjects.

Examination of intercostal arteries with transthoracic Doppler sonography

OBJECTIVE

There has been no study on the measurement of blood flow of the intercostal artery (ICA) or lumbar artery (LA) with the use of transthoracic Doppler sonography. Here, the method of the ICA depiction and flow measurement were described, and we suggested the clinical usage of this method.

METHODS

Twelve healthy subjects were examined. The performance of transthoracic Doppler sonography was approached from the back on lateral decubitus position. The intercostal artery was depicted by two-dimension mode with color flow, and the inner diameter was measured. Peak systolic velocity (PSV), end-diastolic velocity (EDV), velocity-time integral (VTI), and heart rate (HR) were measured with pulsed Doppler, and the blood flow was calculated.

RESULTS

Bilateral ICAs and LAs from Th4 to L4 were measurable with this method. The PSV of Lt Th9 was the fastest at 43.3 +/- 10.1 cm/sec and the PSV of the ICAs gradually decreased as distance from Th9 increased. As for the flow volume, the left Th11 was the greatest at 99.7 mL/min, and the flow volume of the ICA gradually decreased as distance from Th11 increased. The velocity and blood flow of right ICA tended to be lower than the left in the same spinal level.

CONCLUSIONS

Evaluation technique of serial ICAs and LAs was shown. We think that it may be a clinically useful method in the study of spinal cord circulation in the repair of cases of descending thoracic or thoracoabdominal aortic aneurysm.