Electrophysiology Lab

At the EP lab, I had the pleasure to shadow Dr. Zacks while he performed ablations on the heart and installed pacemakers.  The first day I met him, he performed an ablation procedure on a mid-20 year old female who had recently discovered that she was prone to fainting due to a congenital heart defect.  Her heart had an accessory pathway (AP) between the right atrium and right ventricle that predisposed her to mild arrhythmias that interfered with her life-style.  Fortunately, the treatment was relatively safe so she agreed to have a few wires inserted into her so that the doctor could ablate the AP using high-energy radio frequencies.  In less than an hour, the procedure was over and post ablation ECG readings suggested that the patient's heart was functioning normally.

In my opinion, she was one of the lucky ones.  Sometimes the ablation procedures don't run so smoothly.  Take for example the case of an elderly patient that was being treated for atrial fibrillation.  In his case, the boundary between the arterial/venous tissue and the atrial myocardium were deemed as sights that promoted electrical conduction anomalies.  To deal with this boundary, the common procedure is to ablate circumferentially around the superior/inferior vena cava and the pulmonary artery and vein.  To my surprise, this procedure was incredibly difficult due to the lack of good engineering tools.  Although the doctor was assisted by a 3D model of the patient's atrium - mapped using an electrode - it seemed like he ablated most of the atrium.  According to an anonymous doctor, this is usually not uncommon because such damage to the endocardium does not compromise the function of the heart.  Nevertheless, one could use an ablation probe that could be adjusted to form a circle or some other shape. (Get at it guys! :)

Patients can obviously have other problems that can cause the electrical propagation down the heart to fail.  For those that have problems with their SA/AV node, the common procedure is to implant an electrical pacemaker.  Frankly, this procedure seemed very simple (this is a good thing).  Two wires with screws at the ends were inserted into the left subclavian artery and were attached inside the right ventricle and right atrium.  Following, the other ends of the wires were attached to a small pacemaker implanted in a sac near the patient's left clavical bone.  This procedure lasted about an hour.  

Catheterization Lab

In the Cath lab, I shadowed Dr. Wong while he performed angiograms and angioplasty.  From what I could gather, it was routine to do an angiogram on a patient to diagnose abnormal growth of the heart's myocardium, occlusions in the coronary arteries or regurgitation in the chambers. Often, while doing the angiograms, if a doctor observes that the vessel is occluded more than 60%, he/she will usually recommend the patient for angioplasty.  Apparently, most doctors prefer not to perform angioplasty on any occlusion since the stent used in the procedure can cause problems in the future.  Mainly, it has been shown that introducing a stent into an artery raises the risk of a clot unless the patient takes a drug such as Plavix for at least a year.  Nevertheless, if the stent is not flush with the arterial wall, the risk of a clot is very high.  As a result, most doctors will use unique high-pressured balloon to insure that the stent is flush with the vessel wall.  A few doctors will even use an interventional ultra sound device (IVUS) to visualize the lumen of the vessel.  

The IVUS seems like a good way to assess the placement of a stent, but it prolongs the procedure.  As a result, most experienced doctors will not use it.  I personally think the IVUS should be built into the lead that carries the balloon.  This would greatly improve the accuracy and long-term success rate of the procedure since the built in IVUS will allow doctors to visualize the lumen of the arteries while they implant the stent. (Get at it guys! :)

 

Vascular Vernacular

Vascular Surgery
Week 2

Like any other profession, the world of vascular surgery is littered with jargon and acronyms. The first step in figuring out what’s going on is learning the lingo, so here’s your guide to some common language heard around the operating room and clinics.

Vascular Vernacular

First off, let’s outline some major anatomical landmarks so we’re all on the same page. The arterial system of the lower body starts with the abdominal aorta, a continuation of the thoracic aorta (the one in your chest you think about when you hear “aorta”). This splits into two common iliac arteries (CI). Going down one leg (and occurring in each leg), the CI splits into the internal iliac artery and the external iliac artery (EI). The EI continues to the groin and is called the common femoral artery (CFA). The CFA splits again into the profunda femoris artery (PFA) and the superficial femoral artery (SFA). The SFA changes name to the popliteal artery behind the knee. This continues and carries blood to the leg as three arteries—the peritoneal artery which stops at the ankle and the anterior and posterior tibial arteries which perfuse the foot. Got it?

A Few Other Terms You Should Be Familiar With:

AAA
“Triple ‘A’”, or Abdominal Aortic Aneurysm

ABI
Ankle Brachial Index
This test is a ratio of the measures of arterial pressure in the ankle to the arm and can be used to detect peripheral vascular disease.

Anastomosis
The joining of blood vessels, such as during an AV fistula

AV fistula
Arteriovenous fistula
This is the joining of an artery to a vein. It can be created for therapeutic reasons (renal dialysis) or can occur congenitally.

Bulldog
A specific type of vascular clamp

C-Arm
Portable fluoroscopic device shaped like a ‘C’ used for angiograms

Debridement
Removal of dead tissue to promote healing of a wound

Endarterectomy
An operation to remove or bypass plaque or blockage in a stenotic artery

Grand Slam
A specific type of guide wire

Patent; patency
The state of being open as applied to vessels or stents

Profunda
Deep seated, as in profunda femoris artery

Restenosis
Reoccurrence of stenosis, or narrowing of a vessel

What Else?

Learning fancy terms was just part of my experience this week. I got to check out a leg angiogram and a debridement of a leg wound. Debridement will hopefully help the tissue to granulate and improve healing. I also spent time at the clinic and met with some reps from Cook regarding a stent trial. This was really great—I got to see the technical specs of the trial and got a medical company’s perspective on pushing their products to a surgeon.

That’s all for now!

Statistics is scary!

So as I promised, I will be discussing the controversies around lung cancer screening trial lead at NYP and now many other places around the world by Dr. Henschke. So Traditionally to evaluate the merits of a treatment/screening trial (I will be focusing on screening here), clinicians set up what is called a Randomized Control Trial (RCT). In an RCT people are divided randomly into two groups: one which will be screened and one which will receieve either no screening or another form of screening. Clinicians design a regimen of screening for both groups, then screen them for a specified period of time and later on perform a follow up. The efficiency of the screening will be evaluated by what is called the rate of mortality reduction due to screening, which is the number of people who will die of a particular disease of interest over the total number of deaths (in the period of screening).
RCTs have a lot of merit in clinical treatment trials, however, they do not seem to be very informative and efficient as far as screening is concerned. I am simplifying so much here but what I just said seems to be the matter of controversy in the medical community. In the 1970's three RCTs, Mayo Lung Project (MLP), Memorial Sloan-Kettering Lung Project (MSKLP), and Johns Hopkins Lung Project (JHLP) looked at the effect of screening people with a high risk of developing lung cancer with chest radiograph (CXR) and sputum cytology. The MLP (the largest of all three and funded by NCI) after 6 years of screening and about 14 years of follow up, concluded that screening with CXR does improve the survival but does not reduce mortality rate compared to the controled groups. In other words, CXR may be detecting a lot of biologically cancerous, but clinically benign cases that will improve the survival but it is not actually saving lives and that's why the difference in mortality between the two groups did not turn out significant. This result was followed by same results from MSKLP and JHLP. As a result mass screening for lung cancer, at least for individuals with high risk of developing it did not turn into public policy (as opposed to other cancers screenings such as breast cancer or cervical cancer).
So here is the question: it makes intuitive sense that the sooner you catch cancer, the better your chances of treating it. So why the the above RCTs prove the opposite? It's also worth mentioning that a few years ago the same controversy was involved in questioning the merits of annual mamography for women to screen for breast cancer. In this case again a few RCTs disprove the value of mamography screening while a lot of clinicians disagreed with the results. So where's the mystery? What seems to be inconsistent here? stay tuned.......:)

Catheterization Lab

This week I want to take a break from looking at my mentor clicking images, so I went to the catheterization lab in the cardiology department. I observed an angiography procedure. This procedure is used to visualize the blood vessels near the heart. The doctor first threaded a catheter into an artery of the groin region and pushes the tip of the catheter up to the major coronary arteries. Then a contrast agent is released from the tip to light up the blood vessels. Typical images from angiography are as showed below.

The patient has a stenosis in one of his arteries; therefore, an angioplasty procedure is followed. A typical stenosis region is as shown in the left image above (red arrow). It appears as a sudden narrowing of the blood vessels. After looking at the stenosis or blockage area, the physician asked one of his assistant to get a stent and balloon. Then, he uses a guidewire (basically a very thin wire that fits inside the catheter) to guide the stent through the catheter to the area of blockage and placed the stent there. Next, he uses the guidewire again to direct the balloon in place. Then the physician inflated the balloon, so it crushed the plaque and expand the vessels. Finally, he checks the x-ray to make sure the stenosis is no longer there.

Interestingly, a woman who is not a medical staff always walks back and forth between different catheter labs. After talking with a fellow student in the lab, I found out that she is actually from Boston scientific, a company making medical equipments. She is in the hospital most of the time, making sure the doctors know how to use their products, and introduces the doctors to their new products.

This week I also met with Thanh, a research scientist in the MRI imaging lab. He will be working with me on the T1 mapping project. After talking with him, I found out that my project is to develop an image analysis tool for the researchers and clinicians to perform t1 mapping analysis on a sequence of images. So basically I use Matlab to create a graphical user interface (GUI) for them. Well I guess the “good” thing is that I don’t need to kno what t1 mapping is after all.

The Emergency Room On A Saturday Night-Sunday Morning

NYC is a great place, lots of people to talk to, great food to eat, way to many ways to spend money. However, great educational-entertainment is easily obtained if you have access to the back-rooms of the ER at Cornell-Medical Center.....I DO!

Now I have seen many great things~Open Brain Surgery~Busted Aneurysms~Open Heart Surgery~Tendon/rotator cuff reconstruction. But nothing has compared to my 2 am visit to the ER after going out to a nice dinner!

The ER was cluttered with Manhattans elite; drunk CEO's with broken bones, as well as the not so fortunate stab wounded victims from a large street brawl. I was lucky that I went with my scrubs on, since it was hard to distinguish hospital-people in hustle and bustle.

It's hot and humid outside, but so cool in the OR

For the last two weeks I have been shadowing Dr. Schwartz, a neurosurgeon and research scientist at the hospital. So far it has been quite an experience. The first day was extremely hectic. None of us had any idea where anything was. I was nervous about meeting my clinician, mainly becuase I had no idea what to expect. I was given a yellow post-it note telling me to meet him at "Greenburg OR 3." It took me a while, but being a graduate student, I was able to find my way. I showed up at the check-in counter confused and lost in a dress shirt, tie and slacks, receiving just as confused looks from the staff. I told them I was supposed to meet Dr. Schwartz where they then proceeded to tell me that I would not be able to get into the OR with the attire I was currently wearing. After scrambling around, I was able to get some scrubs and head into the OR Room 19. When I first entered, I again received some of the same confused looks from the nurses and residents. The resident came up to me and told me my face mask was put on incorrectly. I felt pretty dumb, but he was nice about it and proceeded to show my how put it on correctly. Dr. Schwartz finally arrived and before I knew it, I was experiencing my first surgery: a muscle biopsy. The first day were relatively simple surgeries. The next two surgeries, were similar ones in that they placed a chemotherapeutic reservoir between the skull and the skin. From there, a catheter was connected and implanted into the brain to help release the drug deep into the brain.

The next day, I observed an endoscopic removal of a tumor through the nasal cavity. The operation consisted of the entire removal of the pituitary gland, which the tumor had infiltrated. The entire surgery took about 7 hours. It was amazing to see how much the doctors were capable of doing despite the size of the tools and how little degrees of freedom they had. Later that week, I saw a removal of the lesion (possible tumor) in the temporal lobe in one patient and the removal of the amygdala and hippocampus in another. I observed a clinical experience in which electrodes were used to stimulate and record electrical activity of the epileptic tissue. As a part of my project, I wll be analyzing some of the clinical data, which should be very interesting.

This week has been just as interesting. Monday there was a case in which the patient had to be kept awake while the brain tumor (near the motor cortex) was being removed. The doctors had to make sure they did not commit any collateral damage to the brain. I also observed a patient that had surface and depth electrodes implanted into the brain. I believe they will be used to monitor his brain activity to hopefully map the focal point of the seizures.

It has been a great two weeks so far, and I expect it to get even better.

Plastics Make It Possible

Every Monday morning at 7 am the Department of Plastic Surgery has their Divisional Academic Conference to discuss cases of interest from the previous week. Each fellow chooses one case that is of particular interest and guides the group through all of the intricate details. It was at this conference that I was scheduled to meet my clinician, Dr. Robert Grant, along with the rest of the plastics crew. I am very grateful that Dr. Grant chose to introduce me in this manner, as I was able to meet just about the entire team all at once and immediately begin to recognize the considerations involved in a plastics case. The meeting was brief, but educational…I was truly amazed at how knowledgeable every one of these surgeons are…they were not only freely tossing around language I couldn’t follow, but were also quoting coded procedures and classifications off the top of their heads.

After the conference, I followed Dr. Grant to his satellite ambulatory clinic where he holds office hours. This was a casual environment and a nice way to start my summer immersion. We saw patients together, followed by debriefing periods in which Dr. Grant would explain his thought process involved in the diagnosis and allowed me to ask questions on just about everything.

As Dr. Grant’s research lab is currently in flux for a few weeks, the remainder of the week was predominantly spent doing rounds with the plastics team and observing lots of procedures in the OR. While both of these experiences were very exciting, rounds were also very nerve-wracking. There are so many patients to see before we hit the OR that we were essentially running from room to room.

On the other hand, the OR is surprisingly much less stressful, yet still very entertaining. I essentially have the freedom to roam around the different rooms and observe the most interesting of the plastics cases...which is very cool. Some of the more interesting ones were a bilateral mastectomy with breast and nipple reconstruction, a ventral hernia repair via surgical endoscopy (using a tubular probe with light and camera apparatus to view internal organs on a monitor) with circumferential abdominoplasty, and an abdominal wall reconstruction after excision of a sarcoma …however, I will save the details for a later post.