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Langendorff device balloon catheter production points introduction
Langendorff device balloon catheter making
The Langendorff model uses retrograde perfusion of the aortic cannula to provide enough oxygen and nutrients to keep the heart beating. The specific steps are:
Insert the perfusion tube into the ascending aorta of the isolated heart, then connect the perfusion tube to the device containing the perfusate. After preheating, oxygenating and adjusting the perfusion pressure, the perfusion drops into the aorta due to hydrostatic pressure. And in the case where the left ventricular pressure is not increased, when the aortic valve is in a closed state, the perfusate is perfused into the left and right coronary arteries through the coronary artery opening at the root of the aorta, thereby functioning as a nutrient cardiomyocyte. Finally, it flows from the coronary sinus into the right atrium until the pulmonary artery is discharged.
video:
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Langendorff balloon catheter pressure measurement technology
The principle of balloon pressure measurement is achieved by the interaction of the water bladder and the ventricular wall. The ventricle contracts, the volume of the ventricular chamber shrinks, the wall of the capsule is squeezed, and the pressure of the fluid converted into the balloon is transmitted to the pressure sensor, which is then collected, recorded, and analyzed by the PowerLab Physiological Recorder and LabChart software.
METHODS: After 5 min of cardiac perfusion, the left atrial appendage was incised, the incision was made through the left atrial mitral valve to the left ventricle, and the other end was connected to the PowerLab Physiological Recorder and LabChart software. The saline was slowly injected into the balloon to bring the intracapsular pressure to 4 - 8 mm Hg (5-10). With the rhythmic contraction and relaxation of the heart, left ventricular systolic pressure, end-diastolic pressure, and developmental pressure can be detected.
Langendorff balloon catheter making points and standards
The ideal balloon should meet the following conditions:
1) as thin as possible; in order to transfer the pressure of the left ventricular contraction as quickly and accurately as possible to the fluid in the balloon;
2) as soft as possible to fit the shape of the left ventricular cavity;
3) Compliance is good enough to effectively transfer the pressure generated by left ventricular contraction to the fluid in the balloon;
4) High sensitivity, with sufficient vibration or compression at 40 Hz, for accurate measurement of dp/dt.
Curtis steel needle groove method
Elastic film balloon manufacturing steps
Step 1: Take the 21st long metal steel needle (waist needle)
Step 2: Blunt the end of the needle
Step 3: About 2 to 3 mm from the end of the needle, the needle engraves a groove
Step 4: Cut the top of the unlubricated condom and place it on the needle (make sure it is long enough to cover the engraved needle groove)
Step 5: Put the first section on the condom at the upper end of the needle, then gradually spiral down, and hit the second knot in the groove.
Step 6: Carefully bend the catheter so that it can easily be inserted into the ventricle through the left atrium
Step 7: Connect the needle to the tee and the saline filled syringe
Step 8: Once the catheter is inserted into the ventricle, the balloon is injected with saline to an initial pressure of 5-10 mmHg.
Skinning method
Elastic film balloon manufacturing steps
· Material
Ultra-thin smooth condom, epidural catheter, 2 cm diameter hollow cylinder, 1 ml syringe, 3-way valve, No. 0 wire, etc.
· "Skin method" balloon production method
Cut a film about 4 cm in diameter from the condom, cover the top surface of the cylinder, gently flatten it, and tighten the index finger and thumb with your left hand. The hand-held epidural catheter enters from the underside of the cylinder, against the center of the film, and gently lifts up. Hold the tip with your right hand and pull the epidural catheter up to a conical shape, about 5 cm high. The assistant knots (single knot) and tightens about 2 cm from the apex in the middle of the cone. Release the left hand, lower the cylinder, and the right hand is no longer lifted, but gently press down, and the epidural catheter is slightly withdrawn to prevent puncture. Carefully pull out the epidural catheter until it is only slightly left in the balloon. The water is injected into the balloon. When the pressure in the balloon is 5 to 10 mmHg, the diameter of the balloon is preferably about 3 mm. Both the height of the cone and the position of the knot have a direct effect on the size of the balloon. If the balloon is the right size, the assistant hits the second knot. If the balloon is too large or too small, the epidural catheter is withdrawn and remade.
Step: Fold a length of line and form a loop at one end. Place the wire on the needle and wrap to allow the ring to protrude through the tip. The end of the short line should pass over the plastic edge of the needle. The long line should be long enough to wrap around the wrap. Hold the tip and loop in your left hand. Take the long line at the end of the right hand, starting at point H (just below the cut end of the film), wrap around the needle and move from right to left. It is important to stay under tension and to entangle quite tightly as it prevents fluid from escaping from the inflated balloon. Continue to wrap the thread around the needle until it reaches the point on the right side of the needle tip. The end result should be a single-layered line that is as neat as possible - remember to pass through the mitral valve as it is inserted, avoiding irritation as much as possible. Pass the end of the wound wire through the coil and hold it firmly. Grab the short-end thread and pull it. This will close the loop and drag the long line so that it is trapped underneath. Cut the remaining lines. Gently bend the cannula to help place it into the ventricle. The syringe is filled with boiling (degassed water) and the balloon is inflated. Clear all air bubbles (repeat and vent the air ball while holding the balloon vertically). Over-stretching the balloon (130μL should be enough - this makes the wrap thinner and creates an oval shape.