Cardioplegic Solutions

A couple of weeks ago,I blogged on the cardiothoracic cases that I have observed.. Since then I have been continously amazed as to how the myocardium is completely paralyzed before it is operated...Before any resection on the heart is performed, the heart is completely stopped(paralyzed) and the bypass machine is tasked to pump and oxygenate blood in the body. Here's what I have just learned about Cardioplegic Solutions...



Cardioplegia in Latin cardio means heart and plegia means paralysis. Therefore, cardioplegic solution is a solution that paralyzes the heart. The solution is mixed with blood and infused into the coronary circulation to induce and maintain paralysis while the heart is being operated on. Perfusion of cardioplegic solution through heart stops the myocardium contraction/ relaxation, reducing its metabolic requirements. During this paralysis period, the heart is uniquely endowed with anaerobic pathways that it uses for energy production. To reduce the body's( heart and brain mainly) metabolic demands, the temp. is dropped from 37.5 to 22 degrees celsius and the heart is injected with the cardioplegic solutions every 40 mins for upto 120 mins. This temp. drop is known to reduce the rate of ischemia by 50%, which is a great thing! Plegisol Solution is a combination of calcium chloride dihydrate, magnesium chloride hexahydrate, potassium chloride, and sodium chloride...Once the mycardium has been sutured and the normal intracellular/extracellular re-established, and the heart starts beating again! Amazing stuff..

Next time you come across this phrase remember heart paralysis!

Dickson

6th Week in Plastics

On Monday morning I attended the weekly resident talk. Later that day I went to Dr. Spector's office hours where I both observed and aided in patient care. Through the previous weeks I have been able to learn where much of the necessary devices and supplies are stored in the offices which enables me to better help Dr. Spector as he cares for the patients. The same patient I have spoken of before came in for a V.A.C. change as he does each week. The abdominal wound has made great progress in my time here. The first time I saw this patient his wound was 1.5-2" and extended about 7" long to about 5" wide at the widest point. The wound was pear shaped. Over the past weeks the wound has decreased to about 4" long and about 3" wide. The depth of the wound has decreased dramatically to about .5" deep. It is interesting to me that with a simple V.A.C. dressing the body is able to close over such a large open wound by itself. This week I helped in changing the V.A.C. dressing. First, we remove the old dressing and Dr. Spector cuts out in dead tissue as this will not help in wound closure. After debriding the wound, we place gauze in the wound and soak with Dakin's Solution. This is a aseptic solution for cleaning wounds what is made of sodium hypochlorite and boric acid (4 %). We allow the patient to sit our the 'rinse cycle' for a few minutes while the wound is soaked in Dakin's. Then we remove the soaked gauze and dry off the wound. The standard oval shaped black sponge is then cut to fit the wound. Often the doctor will cut the sponge half thickness and then cut out the pattern of the wound. This helps to keep the healthy tissue surrounding the wound health and increase drainage from the wound while promoting the granulation of the wound bed. A picture (from www.kci.com) is shown that pictorially shows how the fluid in the wound bed is able to exit through the black sponge and the vacuum is able to help in wound closure. Now that the patient has seen the wound closure capabilities of the V.A.C. and the wound has greatly decreased in size, there are now other options for closure of the wound. Because the patient has also lost weight over this time period, it may be possible to simply elevate the tissue on either side and close the wound. By leaving the V.A.C. on for a few more weeks, this would certainly be possible. It would also be possible, to put a skin graft over the wound to close it. As of now, the patient has opted to keep the V.A.C. dressing on and continue to allow the wound to make progress this way.

Additionally, this week I was able to attend a unilateral mastectomy. The patient has breast cancer in her right breast and decided that removing the breast was the best option. Dr. Spector counseled her on the different reconstruction techniques that can be used and allowed her to decide what would be best for her. The two main options are to complete an reconstruction by removing a portion of her abdomen and forming a breast from that or by simply placing a tissue expander in after the breast is removed. An example of a tissue expander is shown in the image on the right. With the first option, the procedure is called a free flap where tissue is taken from one part of the body and used in another, but it is moved with its own blood supply and hooked into the blood supply around the new site. For the tissue expander, the expander is placed under the muscle and slowly expanded by adding saline ever few weeks until the desired size is reached. Once the size is correct, implants are placed. In either case, addition surgery is required to reconstruct the nipple. In the OR, first the breast team comes in and removes the cancerous breast. The day prior to the surgery, the patient is injected with a dye which then accumulates in the nodes, which can easily be seen during surgery. An incision is made around the areola and then the skin is elevated off of the underlying breast tissue. The nipple and breast tissue are then removed. The nodes are then removed and sent to pathology. Frozen sections are taken and the surgery team is informed whether the cancer is present in the nodes. The sentinel lymph node is specifically checked. This is an indication as to whether the cancer has spread to other parts of the body. Once the breast team has finished, the plastics people come to the OR and begin the reconstruction. The tissue expander is placed under the muscle with a small amount of saline in it. For the next few months the patient will come in periodically to have more saline injected into the expander. The port on the expander is labeled with a magnet so that Dr. Spector can use a magnet externally to locate the port.

Laparoscopic Surgery -- Removing Sigmoid Colon

This week I have a chance to observe Dr. Milson performs a laparoscopic surgery. When I entered the operation room, the surgery is already started. Everyone was pretty relaxed. The patient was lying on the operating table “sounds asleep”, while Dr. Milson was cracking joke and directing the residents what to do. When I walked close to the operating table, I saw there were various long rod-shaped surgical tools sticking from the abdomen of the patient’s body. Three physicians were holding these various surgical tools and watching the screen in front of them. One thing stand out is that the patient’s abdomen is swell like a balloon. Later I found out that in this kind of laparoscopic surgery, the abdomen is usually inflated with CO₂, so the physicians have more room to work with. When I looked up at the screen, u can see all the guts of the patient. Also u can see the ends of the long surgical tools. Several of them are small clamps that use to hold different tissues. One scissor shaped tool is use to cut the connective tissue away from the sigmoid colon. It not only function as a scissor, but has some kind of heating mechanism that will seal the wound from the cutting so not much blood came out. It was quite amazing to see that how three physicians can work cooperatively to remove all the connected tissues from the sigmoid colon. Since it is already hard to maneuver using these long tools, and two people have to hold the tissue in place, so the other physician and cut them away from the colon. After the sigmoid colon is completely remove from the rest of the connective tissue, the doctor took the whole thing out from one of the incision of the body, and cut away the disease part. Then he used a special stable gun to join back the colon and the rectum. Finally, one of the residents performed a leak test to assure the colons are joined completely.

The whole procedure took about an hour and half, which is longer compared to traditional open surgery. However, there are several advantages. First, since only several small incisions are made during surgery, the recovery time will be shorter. Furthermore, blood loss will be minimal. One thing is quite remarkable in this type of surgery is the design of these various surgical tools used in the surgery.

Electrophysiology Lab

This week I went to electrophysiology (EP) lab in cardiology. In this laboratory, I mainly observed two procedures: implantation of a artificial pacemaker and Electrophysiology study.

The artificial pacemaker is a programmable device that generates electrical impulse to the heart to regular heart beats. The electrical signal is delivered by electrodes contacting the heart muscles. Usually people need a pacemaker when their own natural pacemaker is not working properly. When I first entered the EP Lab, they made me wear this 60 pounds lead to prevent radiation from the x-ray. It is quite tiring even wearing it for an hour, I must say quite admired these doctors are able to wear them all day long and perform operations.

The procedure itself is actually quite simple. The physician made a small incision on the right side of the upper chest, and then he threaded two special wires (in which the proximal tip contains an electrode) into the body and place the electrode near the heart muscle. Then he asked the assistant to generate different electrode signals through the wires and watch the pattern on the ECG. Then he adjusted the placement of the wires and repeated the signal generation several time till he got the desired ECG signals he wanted. Finally, he obtained a pacemaker and connected the wires into it and put the small device near the incision area. Then he secured the device under the skin and sewed up the wound. After the implantation is done, the physician went to a computer and remotely programmed the device.

From talking with the physician, I found out that these peacemakers generally last 5 to 10 years depending on the condition of the patient. Some patients like the one he just operated on only require pacing at certain time, but some other patients require the artificial pacemaker to work all the time.

The second type of procedure is an electrophysiology (EP) study. Normally, electricity flows throughout the atria first and then pause for a moment before the electric signal is propagate to the ventricles through the atria-ventricular (AV) node. The electrical signal brings about heart muscle contraction. The orderly pattern guarantees that the heart pumps blood efficiently. Whenever something wrong along the electrical conduction system, it causes a heart rhythm disturbance (termed arrhythmia), which will leads to inefficient pumping of the blood out to the body. The reason for an EP study is to find out the cause of such arrhythmia. Usually during an EP study, wires are placed on the sinus node (natural pacemaker), one on the AV node and one on the bundle of His (which is the wire that sends signal from AV node to the rest of ventricles). They also place several wires on the ventricles and atriums depending on situation. Then they will generate electrical signal on different places, and observed the corresponding signal recorded elsewhere to try to figure out the cause of the arrhythmia.

Vascular Research

Vascular Surgery
Week 6

Vascular Research Project

My research project looks at the outcomes of vascular procedures in women. My surgeon mentor and others think that there may be a relationship between the outcomes of vascular procedures and hormone replacement therapy (HRT), osteoporosis, and menopause. “Outcome” is defined as patency—that is whether or not a vessel is open at a follow-up visit after surgery. After writing a script that was approved by the surgeons in charge, I called a list of about 300 elderly female patients (average age = 76) to ask them about HRT, osteoporosis, and menopause. Awesome!

The Patients

Some women were surprisingly sharp and inquisitive and really opened up to me over the phone. The responses were understandably colorful—if the patient felt better they exalted their surgeon while some patients with poor outcomes told me they had found new surgeons and hospitals entirely. Often the same surgeon was regarded in both positive and negative ways. This is understandable considering the variable difficulty in treatment that occurs between patients and procedures.

One thing that surprised me was that patients were very willing to open up to me over the phone—I heard some fascinating life stories. Alternatively some patients would not talk to me at all—they didn’t trust that I was calling from New York Presbyterian Hospital and requested a written questionnaire while others could only speak in Spanish. Other difficulties like disconnected telephone numbers and no answers left the respondents to about 30%. From these patients I got some interesting data regarding patency, HRT, and osteoporosis—really interesting data…that I can’t show you here because it might get published! Stay Tuned!

Two anastomosis devices

In the last blog entry, I generally described the procedure of colectomy and making a J-pouch. In this entry, I want to introduce two important surgical devices that are used during this operation.


The first question is how to remove the colon. The magic gadget is called GastroIntestinal Anastomosis (GIA) device, which has two functionalities. First, it’s a cutting device that cut a piece of colon into two, as Shown in Fig. 1. At the same time, in order to prevent bleeding, it sutures the two edges of the cut simultaneously, as in Fig. 2. Two stagger rows of staples will be fired when the surgeon push the middle hidden blade to cut the colon. In this way, the entire colon can be removed easily and safely.The second question is how to connect the remaining part to the anal control muscle. This is more complicated. The End-to-End Anastomosis device has a detachable anvil at the distal end. To operate, the surgeon needs to put the anvil inside the remaining intestine and the EEA through the anus. Since both the anvil and EEA device have pointed piercing structure, they can connect to each other. After they are connected, squeeze the trigger to make a circular cut and anastomosis at the same time. Therefore, the remaining intestine is safely connected to the control muscle. After pull the entire device out from the anus, this step is finished.

A variety this week...

This past week, I participated in a variety of activities. However, I mainly concentrated on completing my research project for the program. My project consists of removing motion artifacts from data acquired from a clinical study. This investigation involved a epiltptic patient who had suffered from seizures for more than 12 years. Anti-epileptic drugs were not effective and the patient's last resort was to have the epileptic tissue removed from her brain. Prior to the resection, the lab that I am working for wanted to study the effects of electrical stimulation on blood flow and hemoglobin concentration of epileptic tissue. To see changes in blood flow and hemoglobin concentration, we utilized the intrinsic optical signal. What this means is that at certain wavelengths, changes in absorption or reflection correlates to changes in blood flow and hemoglobin. In this case, 570nm and 610nm were used to observe changes in blood flow and hemoglobin, repspectively. In addition to the intrinsic optical signal, we also wanted to see the resultant electrical activity due to stimulation. In order to do so, my clinician placed two sets of surface electrodes, one for stimulation and one for recording resultant electrical activity. A footplate was placed above the elecrodes to help keep the brain in place, to reduce motion artifacts as much as possible. The tissue was stimulated at different frequencies (10, 50, 100 and 250 Hz) and at a constant charge. My job in this whole study is to remove motion artifacts seen in the optical data. I was mainly manpower for the project. The code was already written, but I was the poor subject who had to filter 34 sets of data. At this point I have completed all the sets and am going to get ready to analyze what the results mean. Ultimately, far down in time, I believe this would like to be a therapy for epileptic patients in order to help the damage tissue by reducing seizure activity. It is somewhat unclear to me at this point, but I will hopefully have it clarified in my last week here.

Outside the lab, I was able to observe a mastectomy with my homegirl Emily and my main man, Campolongo. The patient has cancer in her right breast and they were going to remove the breast tissue. I was amazed at how much tissue they took out. The next steps were to place an "expander" below here pectoral muscle for her future implant in a later surgery. Then within a couple months, she would have to undergo another surgery to have her nipple reconstructed. I had no idea that the whole process would take 3 operations. Another interesting procedure we got to see was how they determine what lymphnodes were more likely for infiltration. Apparently lymphnodes are most likely place for cancer to spread to. Prior to the surgery, a blue dye and a radio isotope is injected into the patient. I believe that is specific to the lymphnodes to areas surrounding the breast tissue. The blue dye is used to help the clinician find them. The radio isotope is used to determine how "hot" they are. From what I got, the hotter they are implies that they are more vascularized and more prone for cancer infiltration. However, the reading has no indication on whether the cancer has metastasized or not.

Next week I plan on joining Dr. Frayer and my main man Campolongo to observe little babies. Giddy up! Till then, I say "Good day!"