The flow of blood can cause the vein walls to vibrate creating a humming noise which can be heard by the subject.

A small catheter delivers radiofrequency energy (instead of laser energy) directly into the vein wall, causing it to heat up and collapse.

Foam makes better contact with the inside of the vein walls and stays in the vein longer.

Sometimes they swell so that the vein walls become stretched, thin, and irritated by passing bowel movements.

The catheter is a foreign body in the vein and often provokes an inflammatory reaction in the vein wall.

Other such ectopic pacemakers can even lie within the pulmonary vein and thoracic vein walls.

Estrogen can weaken the vein walls, leading to the changes that cause varicosities.

Use your motors moderately and take advantage of the first weakening of the vein wall through miniaturization to burst through.

The ship moved forward and, as the prow touched the vein wall, Morrison could feel the slight vibration of the laboring motors.

The most important factor is circulating hormones that weaken vein walls.