Research on endoscopic saphenous vein harvesting for CABG as well as immunosuppressant and antineoplastic qualities of verapamil.

                   This week I researched the technique that extracts the greater saphenous vein for CABG surgery, that technique being endoscopic saphenous vein harvesting. Endoscopy is a procedure that involves inserting a thin malleable tube with a light and camera attached onto it to observe and remove any abnormalities within the vessel wall as well as to locate and extract veins. In the past physicians used to make long open incisions down the patients leg (because the greater saphenous vein extends from the back of the venous arch in the foot to the femoral arteries near the groin) to                                          extract the amount of the vein they needed to perform bypass surgery. This procedure was disliked by patients as well as some physicians for two reasons. The procedure increased the chance of the patient contracting an infection and it showed a long scar going down the patients leg, which the patients found aesthetically displeasing. Endoscopic saphenous vein harvesting was developed as a less invasive alternative to the open incision procedure. The endoscopic saphenous vein harvesting procedure is as follows. Physicians make a small incision in the groin (the endpoint of the greater saphenous vein) and make one-two tiny (~3cm) incisions near the medial portion of the leg (near the knee). They then insert a trocar (a sharp, pointed instrument that is used with a cannula to puncture a portion of the body) into the incision in order to fill the tunnel created between the incisions with carbon dioxide. After the trocar is inserted a conical dissection cone is moved toward the incision in the groin because this is where the anterior surface of the greater saphenous vein is. After this circumferential blunt dissection (total circumference or perimeter of a blunt dissection, which involves separating tissues along its natural dividing line (animal cell cleavage via mitosis) without cutting the tissue) is utilized to naturally divide the posterior and lateral sides of the vein. Before the vein can be extracted the physician wants to make sure that normal blood flow continues in the body. They ensure this normal blood flow by isolating the collateral branches in the leg through bipolar electrocautery (A small instrument that passes a high voltage and high frequency current between its two electrodes to isolate a small portion of a vein). By isolating the collateral branches they are ensuring that blood that used to flow through the greater saphenous vein will now flow through the collateral branches. After bipolar electrocautery is performed the physician ligatures (tie up the ends of the vein) the greater saphenous vein and extracts it. Then they dilate the vein through a cannula (a tube that is inserted into the body to allow the trocar to occupy its lumen and puncture a portion of the body) to prevent endothelial dysfunction. After this the physician double clips the ends of the vein and flushes the vein with a cleaning solution.  Finally they suture up any avulsions (tears that occur by forcibly removing a structure or part of a structure) on the vein, thus making the greater saphenous vein acceptable for CABG surgery.

                I also researched verapamil (a calcium++ channel blocker) and its immunosuppressant and antineoplastic (cancer cell destroying) qualities. The reason why I researched this is because paclitaxel and other chemotherapy drugs are the main drugs used in drug-coated stents. Paclitaxel has both immunosuppressant and antineoplastic qualities, and I wanted to ensure that verapamil had similar qualities in order to ensure its viability as a coated drug on an internal mammary artery graft. From researching studies from NCBI (national center for biotechnology information) I found that verapamil does exhibit immunosuppressant qualities. The study said however that most immunosuppressant drugs block adhesion molecules by blocking their secondary messengers protein kinase C (PKC)and/or calmodulin molecules in order to prevent a foreign organ or foreign object (drug-coated stent) from being rejected. The researchers did not observe verapamil blocking either PKC or calmodulin, which therefore did not inhibit adhesion molecule expression. The conclusion of the study stated that verapamil has immunosuppressive qualities, though their origins are unknown. In the second study I researched from NCBI, it stated that verapamil was able to kill multidrug resistant cells. Multidrug resistant cells typically are cancerous cells that are able to overcome the effects of certain chemotherapy drugs. The study identified that the way to destroy multidrug resistant cells is to overcome the Vinka alkaloid resistance that these cells inherently have (Vinka alkaloid's origin is from the Madagascar periwinkle plant, and they are used as chemotherapy drugs). The two Vinka alkaloid drugs the study focused on were vinblastine and vincristine. The goal of the study was to observe any similar physiological characteristics between verapamil (and other compounds) and vinblastine and vincristine. The researchers found that verapamil and vinblastine had three areas of structural homology, and by measuring the hydrophobicity and molar refractivity of verapamil they were able to determine that verapamil and a few other compounds were able to increase the antineoplastic qualities of Vinka alkaloids, thus enabling them to destroy multidrug resistant cells.          

                The most exciting event that happened this week was Tuesday in the afternoon. I witnessed a patient have tachycardia and go into cardiac arrest after finishing his stress echo test. Allan the Echo tech rushed to get the crash cart and Dr. Goldberg immediately performed chest compressions and a precordial thump (this generates 10 joules of electricity in the patient's chest) to the patient's chest to get a stable heart rate. When the crash cart arrived the patient got their heart rate down to 200 bpm and were slowly stabilizing their heart rate. The patient was given beta-blocker medicines to lower their heart rate and the paramedics arrived within 15 minutes and took the patient to TMC. The patient is undergoing CABG surgery today at TMC. This experience opened my eyes in my outlook on medicine because it showed me that there has to be a constant alertness by the physician and medical staff to react instantly to any medical emergency.