Biventricular Assessment of Cardiac Function and Pressure-Volume Loops by Closed-Chest Catheterization in Mice

This protocol allow a comprehensive and robust characterization of cardiac function, as well as quantification of systolic and diastolic function in left and right ventricle of mice. This technique propose a global characterization of cardiac function in mice as it propose a left and right categorization in the same animal. To begin, isolate the right carotid artery by blunt dissection to displace the sternal hyoid muscle laterally to expose and isolate the right carotid artery.

Then use forceps sand blunt dissection to isolate the carotid artery from the vagus nerve and pass three surgical 4-0 sutures under the artery, but not the nerve. For right jugular vein isolation, displace the submandibular and parotid glands laterally. To visualize the right jugular vein and use the forceps to bluntly dissect and expose the right jugular vein.

Carefully dissect the vein to remove the surrounding fascia, and pass the forceps under the jugular vein. Pass a surgical suture under the vein, and tie the suture to the cranial side of the vein. Use a hemostatic clamp to apply gentle traction on the suture in the direction of the head, and pass two additional sutures under the jugular vein.

Use a second clamp to gently pull the most distal suture in a caudal direction and make a loose knot in the middle suture. Then place several drops of warmed physiological saline onto the vessel at the site of the anticipated venotomy. For catheterization of the right ventricle place the mouse under a stereo microscope and identify the jugular vein.

Gently apply superior traction to the vein and insert a curved 30 gauge needle between the cranial and sutures at a 140 degree angle. To ensure the needle enters in a coaxial manner. Upon insertion, move the needle to dilate the venotomy and insert a six millimeter catheter tip under the needle into the venotomy.

After advancing the catheter into the right ventricle, monitor the classical right ventricular pressure waveform on a continuous monitor to confirm the correct positioning of the catheter. If necessary, gently rotate the catheter shaft until an optimal placement of the catheter along the axis of the right ventricle is achieved. To ensure the correct position of the catheter into the right and left ventricular, you have to carefully read and interpret The pressure, volume, magnitude, phases, traces, at the same time that you're moving the catheter.

When an optimal pressure magnitude loop signal has been obtained, press enter on the console to perform a baseline scan and monitor the heart rate. To generate the pressure volume loops, change the X-axis parameter from magnitude to volume, leaving the pressure as the Y axis. When the pressure volume loop signal is optimal.

Record for 30 seconds. At the end of the analysis, stop the recording. Then place the removed catheter in heparin sodium chloride solution.

For catheterization of the left ventricle, gently elevate the right carotid artery with forceps, and tie the cranial suture, thereby occluding the artery. Use a hemostatic clamp to gently apply cranially directed traction on the vessel and use a clamp to pull the most distal suture in a caudal direction. Make a loose knot on the middle suture and add several drops of warmed physiological saline onto the vessel at the site of the anticipated arteriotomy.

Use the microscope to focus on the cranial section between the caudal and the middle suture and gently apply superior traction to the artery. After inserting the catheter as demonstrated for the right ventricle, confirmed that the pressure channel recording shows a typical aorta trace, advancing the catheter into the left ventricle will be evident from the sudden market drop in diastolic pressure from the aorta. To stabilize the left ventricular pressure, use the pressure volume loop to confirm the correct positioning of the catheter in the left ventricle.

Stop the recording and remove the catheter. Place the catheter in heparin sodium chloride solution and tie the caudal suture. Then clean the catheter with an enzymatic detergent.

In this figure, representative optimal pressure loops generated from a catheter correctly inserted through the jugular vein and advanced into the right ventricle can be observed. Improper positioning within the right ventricle is evident by the appearance of flawed pressure volume loops. Optimal retrograde placement of the catheter across the aortic valve into the left ventricle also results in a specific pressure loop pattern.

That presents as flawed loops in the event of an improperly positioned catheter. This technique allows the acquisition of comprehensive left and right ventricular systolic pressure values. It also provides diastolic parameters, and yields information about numerous advanced measures of contractility and lusitropy.

This technique also facilitates assessment of the efficiency of the left and right ventricle and the afterload of the ventricle's phase. This technique could be used to assess right and left ventricular function in cardiovascular disease. For example, it could be used to assess right ventricular function in response to increased afterload in pulmonary hypertension.

Overall practice, good elimination field, good surgical tool, keeping the carotid angular vein hydrated is the key of success of this procedure.