Administering contrast agent (healing potion) to a rabbit’s heart is no small feat. Garrett rallied his spirits, prepared for everything:

Complete anesthesia! Previously, it was just local anesthesia with restraints, but now sparing no spells, it must be general anesthesia!

Electrocardiogram! Connected to recording devices, constantly alert for any atrial fibrillation or arrhythmias!

Invasive blood pressure monitor set up! A student stood by, unblinkingly watching the mercury column, ready to report any anomalies!

Oxygen saturation monitor ready!

The heart is such a delicate and sensitive rascal, even a slight touch or procedure can cause problems. Arrhythmias, ventricular fibrillation, cardiogenic shock, cardiac arrest – it can throw any number of issues at you.

Even normal hearts are like this, let alone problematic ones.

When Garrett had previously worked on closing arterial ducts, he tried many times, carefully controlling the vines to not touch the heart or blood vessels to avoid spasms. Now, he needed to push healing potion into it...

Who knows what kind of trouble it would cause when the heart wall came into contact with the healing potion.

"Are you ready?"

"Ready!"

Leon Carlos on the left and Reverend Matthew on the right, both replied. Garrett took a deep breath, initiated the growth of vines, and made an incision in the rabbit’s femoral artery, guiding the vines up through the femoral, abdominal aorta, and thoracic aorta, reversing into the heart. Then, the tip of the vine slightly opened, and Garrett’s hand on the other end slightly expanded, one, two, three!

He drew back a small amount of fresh blood to ensure there were no air bubbles inside the vine. Then, connected to a syringe, he pushed the healing potion!

In his meditative vision, the faint golden light of the healing potion advanced less than a foot before its speed slowed dramatically. Finally, it disappeared into the blood vessel, mixing with the blood.

"Uh... teacher..."

"Uh... Garrett..."

Both spell casters, focused on the rabbit with their [Detect Magic] spell, looked towards Garrett. He helplessly shook his head:

"Ah, the pressure is too low..."

No helping it, the force with which the heart pumps blood is immense. The pushing pressure was too low, unable to withstand the arterial blood pressure, the contrast agent simply got pushed back!

Try again!

Still no good, the pushing force was insufficient. It needed to be faster, stronger!

Garrett dispersed the vines, stopped the bleeding in the rabbit’s femoral artery, and looked at the invasive blood pressure monitor, burying his head in calculations:

The reading on the invasive blood pressure monitor placed in the brachial artery was...

Translating that to the root of the aorta would be...

The pressure he needed to inject the contrast agent should be... the speed of injecting the contrast agent should be...

"Oh my god!"

Garrett suddenly exclaimed. The spell casters around him looked puzzled as he frantically pressed on the syringe, his forehead nearly steaming:

Based on his calculations, he basically had to inject 2.5 ml of healing potion into the rabbit’s heart against a pressure of 130 mmHg within 1/4 second! And the injection pressure... the injection pressure...

Was freaking 30,000 mmHg!

Thirty thousand!

Garrett’s vision blurred.

Had he calculated wrong?!

Garrett truly hoped he had. But he distinctly remembered from his previous life in the hospital that cardiac angiography required a high-pressure syringe. That thing wasn’t just a needle; it was a machine with various parameters to adjust.

He never really paid attention to the specific parameters back then...

If the injection pressure really needed to be that high, then that number was simply not achievable by hand! It had to rely on a high-pressure syringe, leveraging mechanical and electronic power!

Reason told him: right or wrong, try and see. Moreover, with the simple methods and conditions he had, he really could achieve it.

"I’ll give it a try!"

Leon Carlos watched bewildered as Garrett left the rabbit and dashed out of the lab. He quickly followed, watching as Garrett rummaged through the storage, pulling out a mercury trough, inserting the syringe beneath the mercury, and forcefully pressing the plunger...

Couldn’t press it.

Completely unmovable.

Hoping to push 10 ml of water into 13 cm deep mercury in one second using just thumb strength was a dream. Even if he had the strength, the friction of the glass syringe wasn’t enough; to have sufficient friction, the syringe’s strength wasn’t enough either...

Otherwise... try another method? Garrett thought left and right, coming up with a second method:

Using transmutation to construct a metal frame, fixing the syringe on the frame, connected to

the vines, deeply inserted into the mercury. Enchant the syringe with a [Higher Magic Weapon] to increase its strength; then, stand back—

"[Magic Missile]!"

Bang!

The Magic Missile accurately hit the piston head. Luckily, the syringe didn’t shatter but shot straight forward; even luckier, the frame withstood the test, not collapsing.

In an instant, the liquid inside the piston was forcefully pushed, all shooting into the bottom of the mercury, pushing away a small clear liquid cluster.

"Yay! It worked!"

Garrett jumped up cheering. He tried several more times, finding the optimal output size for [Magic Missile], happily holding the metal frame returning to the operating room. The magic version of a high-pressure syringe, successful!

Fixing the frame, connecting the syringe, connecting the vines, attempting cardiovascular angiography again. The vines traveled up the femoral artery, exploring into the rabbit’s heart. Drawing back, connecting the syringe, one, two, three!

"[Magic Missile]!"

Under the meditative vision, the pale golden image of the healing potion, moving rapidly forward along the catheter...

"Boom!"

The vines exploded.

The magically grown vines, still being of plant nature, didn’t have sufficient wall strength...

Sigh...

Garrett tried again, and again, and again. He finally realized sadly, even as a sixth-level magic user, a sixth-level priest of the God of Nature, the vines he could generate...

Just didn’t have enough strength.

Truly tragic.

So, it still came down to the material?

The assistants watched his changing expressions—joy, worry, cheering, and head-holding in dismay. Reverend Matthew cautiously asked:

"Garrett, what happened? Can we help?"

Garrett wiped his sweat, briefly explained his experimental purpose, concept, and the difficulties he faced. Reverend Matthew listened silently, pondered for a moment, and seriously suggested:

"If the arterial pressure is that high... why not try the vein?"

...That’s a good question. Garrett wiped away a second round of sweat, collapsed onto a stool in the corner, his voice tired:

"What’s the pathway of blood circulation?"

The pathway, Reverend Matthew, having worked in a hospital for so long, indeed had seen the information. But asked to recite it, he couldn’t say. Garrett’s gaze swept over, and Leon Carlos stepped forward, his voice clear:

"From the left ventricle to the aorta, then to various arteries, returning through various veins, entering the right atrium. Right atrium to the right ventricle, right ventricle to the pulmonary artery, then from the pulmonary veins returning to the left atrium, left atrium to the left ventricle, again entering the aorta."

"Ah... Oh!"

Reverend Matthew followed his description around in a circle, suddenly understanding. So, injecting healing potion through the vein would enter from the vein to the right atrium, then circulate through the lungs, reaching the left atrium.

In that case, the required amount of healing potion would be too large.

And to tell the truth, healing potion, after all, cannot replace blood. A large amount of healing potion injected into the heart, circulating in the pulmonary vessels, what consequences it would cause, nobody could say for sure.

"If it really doesn’t work, we might just have to try from the vein..."

Garrett murmured in resignation. He barely stood up, again initiated the growth of vines, moving up from the rabbit’s femoral vein. This time, pushing in 2.5 ml of healing potion, it dispersed into the lungs and was immediately gone;

Then, pushing in 5 ml at once, still gone;

Increasing the healing potion dosage to 10 ml, 20 ml, finally, on the imaging returning from the pulmonary veins, appeared the golden light of the healing potion. However...

"Beep beep beep beep—"

The electrocardiogram screen urgently signaled an alarm. Garrett turned to look at the waveform, also glanced over the oxygen saturation monitor, immediately dispersed the vines, and started compressing the rabbit’s heart:

Ventricular fibrillation! The oxygen monitor’s color showed an ugly deep red, not the vibrant fresh red!

Definitely, too much potion was pushed, replacing the blood, causing oxygen deprivation to the heart...

The first attempt failed. The second attempt failed. After failing continuously three times, Garrett sighed, rejecting this method:

"Let’s still think about how to withstand arterial pressure..."

Material science wasn’t up to par, truly headache-inducing. But thinking of future interventional catheter materials, things like polyamide, polyurethane, hydrophilic coatings, tensile strength, blood compatibility, biocompatibility...

Garrett still felt that even given two more lifetimes, he couldn’t work it out; better to think of something else with the vines.

Strength couldn’t be reached, was there another way to bypass it? If he had

sufficient mastery in spatial magic, he could traverse space, directly delivering the healing potion to its destination...

"That... what if we let the vines swallow the potion and then spit it out at the spot?"

Reverend Matthew wildly suggested. Garrett was about to say "What joke is this" when a thought struck him:

That’s right!

This is a vine, not a catheter! It’s alive, not dead! It can be induced to grow, it can be controlled to change shape!

By continuously pushing the healing potion through the inside of the vine, directly delivering it to the front, storing it there, then, the front end of the vine could just dissipate away!

Especially since the aortic arch is relatively thicker than the femoral artery, allowing the vine in this segment to grow thicker, accommodate more healing potion, and not touch the aortic wall, this method...

Compared to desperately struggling with a high-pressure syringe, was more feasible, wasn’t it?

Said and done. Garrett jumped off the stool, rubbed his hands together, once again diving into the experiment. This time, the vine continuously writhed, its front end swallowing in the healing potion, growing thicker and sturdier. Finally, it plunged into the heart—

The pale golden magic image finally exploded perfectly in the rabbit’s left atrium.

Success!

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Source: Webnovel.com, updated by Aunomay