347.A 62-year-old man reports to you that at times he has some chest
pain and thinks that his heart is notbeating at an appropriate rate, mainly
too slowly, but occasionally too quickly. You send him for a 64 slice helical
CT to look at the blood supply to the sinoatrial node. The sinoatrial artery
supplies blood to the sinoatrial node. Which of the following is the best
description of the blood supply for the sinoatrial nodal artery?
a. Blood always comes from the right coronary artery
b. Blood always comes from the left coronary artery
c. About 60% of the time blood comes from the right coronary artery and about
40% of the time blood comes from the left circumflex artery
d. About 60% of the time blood comes from the right marginal artery and 40% of
the time from the left marginal artery
e. Blood usually comes from the posterior interventricular artery regardless of
whether that has originated from the right or left coronary artery
348.The major venous return system of the heart, the coronary sinus,
empties into which of the following structures?
a. Inferior vena cava
b. Left atrium
c. Right atrium
d. Right ventricle
e. Superior vena cava
349.A 36-year-old male bartender is brought by ambulance to your emer-
gency room because a patron jumped over the bar, grabbed an ice pick,
and stabbed him in the chest rather than pay his bar tab at the end of the
night. The ice pick entered the chest about 2 cm to the left of the sternum
in between the fourth and fifth rib. Upon examining the bartender, you
note very little blood is coming from the puncture wound and normal lung
sounds from both the right and left lung. However, his heart is beating
rapidly at 100 beats per minute, his external jugular veins are bulging, and
you have difficulty hearing his heart sounds. You order a PA and lateral
chest film because you suspect which of the following?
a. Hemothorax
b. Pneumothorax
c. Cardiac tamponade
d. Aortic valve stenosis
e. Deep venous thrombosis
Thorax 467