Discussion
Postoperative hemorrhage in cardiac surgical patients have been
associated with surgical team experience, effects of hemodilution,
hypothermia, inadequate reversal of heparin, thrombocytopenia, impaired
platelet function, deletion of coagulation factors, and
fibrinolysis.1,6,10 However, RV laceration from a
fractured sternal wire is rare. One other case by Gong et al discusses
fatal bleeding due to sternal steel wire fracture. Similarly, the cause
of sternal wire fracture was thought to be due to increased cough in
this case.
There are different methods used for sternotomy closure including a
series of wires or a figure-of-eight method. With all types of sternal
closure, there is some movement of the sternal halves under
physiological loads, but with regimented sternal precautions
complications are minimal.4 The mechanism of sternal
fracture is generally thought to be caused by patient movement, but a
recent study in the Journal of Orthopedic Research performed a
biomechanical evaluation on the role of cerclage wire failure. Sternal
wires have a material yield or failure strength, which if surpassed
leads to deformities of the material.2 If sternal
wires are to remain the gold standard for sternotomy closure, new
techniques and/or materials must be developed to ensure tensile strength
is not surpassed.
Risk factors for sternal dehiscence include COPD, re-operative surgery,
renal failure, diabetes, chronic steroid use, morbid obesity, concurrent
infection and acquired or iatrogenic immunosuppression. Our patient had
an existing diagnosis of COPD, which brings to question whether an
alternative method should have been used as primary closure.
A one-year follow-up of the ZipFix (Johnson and Johnson, New Brunswick,
NJ) trial showed greater clinical advantages with regards to pain and
sternal dehiscence post-surgery by using sternal ZipFix compared to
conventional steel wire closure.8 Recent studies
suggest that rigid plate fixation may lead to reduced sternal
complications in high risk patients, improved perioperative survival,
decreased length of hospital stay, improved pain and activity management
with improved osteosynthesis.3,7,11 While other
innovative techniques of sternal closure have been discussed such as
reinforced wires, sternal plating and cables; none of these methods have
been found to be reliable techniques or cost efficient when compared to
sternal wires.3,4