• For accurate determination of cross sectional luminal narrowing of coronary arteries and animal.

• Especially important for correlation with premortem coronary angiograms in stented and non stented arteries.

• Optimal in cases of myocardial infarction or coronary bypass cases



Necessary equipment

• Plastic tubing

• Various sizes of rubber stoppers with fittings for tubing

• Formalin reservoir (2-5 L) at 1.3 meters above specimen [Figure 1]

• String

• Clamps to occlude formalin flow in tubing

• Perfusion pump (optional)



Method

• Affix rubber stopper to ascending aorta or arch vessel, selecting appropriate size [Figure 2a, Figure 2b]

• Remove adventitial soft tissue in area of stopper (otherwise stopper will slip off)

• Tie string (usually 2 or more are necessary) around aorta and rubber stopper (there are usually grooves in stopper to prevent slippage)

• Attach plastic tubing from stopper to formalin reservoir

• Allow filling of tubing by releasing clamps and/or filling reservoir with formalin (manually, or with pump)

• Watch coronary arteries and aorta distend with formalin (hoping that stopper does not pop off)

• Watch for leaks; adequate perfusion is easily determined by palpating ascending aorta for turgidity.

• Generally, 30 minutes of perfusion fixation or 3 liters is adequate, but longer periods are acceptable; after perfusion fixation, transfer specimen to immersion fixation.



Caveats

• In cases of aortic incompetence, coronary perfusion is suboptimal and artifactual left ventricular dilatation and wall thinning will occur.

• Heart weights are increased beyond immersion fixation by about 25%; always weigh heart prior to fixation.



Coronary Arterial Tree

• Each of the major arteries are evaluated and stent locations are determined by x-ray of the heart and further dissection. Also, in case of no stents x-ray of the heart is useful to determine the extent of calcification. [Figure 3a, Figure 3b]