Saturday, July 30, 2005

Jeff Ballyns 3rd Week Blog

Monday: Tunde and I met with Dr Potter and observed her go through the wet readings for the day. One of the cases of particular interest to me involved the case about a meniscal tear which could be denoted on the medial side of the knee where one horn was significantly compressed to the side. This compression indicated that the meniscus have been torn and also worn away with significant signs of osteoarthritis present. There was a large list of vocabulary words that were introduced, these include:

Gastricnemia – muscles of the calves composed of lateral, solace and medial.

Onset fracture – a break in the bone due to poor geometry.

euroma – fibrosis tissue (scare tissue) surrounding a nerve (sensory nerve).

Humphry – Secondary stabilizer of the knee (works with the PCL)

Wristberg – other ligament of the PCL that attaches to the meniscus.

Valgus – bent medially (knock kneed)

Varus – bent laterally (bow legged)

Coalition – fusion of a joint (cartilage, bone)

Secimoid – free floating bone (ie. Patella and the bone that is the ball of your foot).

This is an examples of a meniscus with a tear in the posterior horn. You can see that the horn is pushed out posteriorly from the knee signifying that there is a tear. The image was provided by Dove Open MRI

To end the day I met up with Devon and Lilly to observe them dissect the adult knee joints to gather articular cartilage samples. I noticed big differences in the amount of freedom they have with contact with the joints and are still able to avoid contamination problems so I requested a copy of the protocol to see if they are using a different protocol.

Tuesday:

Sat in on the medical student meeting where they discussed their projects one that particularly struck my interest was the one about FTIR to diagnose bone composition. The device seemed to have significant similarities to MRI however FTIR gives more quantitative data as opposed to qualitative data.

Wednesday: Attended Dr. Potters MRI physics lecture the first of three.

Thursday: Shadowed Dr. Marx observed an arthroscopy knee surgery and a shoulder cuff repair. One thing of particular interest with the knee surgery was how Dr. Marx had to cut and remove part of the medial meniscus be cause it was unstable and not performing properly. Dr. Marx said that this portion is often removed because it is not securely fastened and could get pinched and cause major discomfort to the patient.

This is what a knee arthroscopy looks like on the outside and then this is what the doctor sees on the camera.

Images are provided by The Haptic Training System

And arthroscopy knee

The shoulder cuff repair was a fairly short operation since the patient seemed to have no major tears but a severely inflamed bursa. The bursa is a sac sandwhiched between the rotator cuff muscles and the outer layer. They serve to lower friction between muscles sliding against one another.

Image provided by Winchester Hospital

Friday: I shadowed Dr. Warren in the ambulatory section of HSS. I watched him perform a shoulder debrisment and a shoulder cuff repair. The shoulder dibrisment was for a patient that had a total shoulder replacement done on him before. Dr. Warren removed surrounding fat and swollen tissue in the area. It was noticed that the Glenoid implanted earlier had become loose, so it was removed and then packed with bone crushed from a femoral head. The glenoid is the articulating surface which the humoral head moves across. This can be seen below along with some images of what an artificial glenoid looks like.

Images provided by JointReplacement.com and Duke Orthopedics

The final surgery was of a shoulder cuff repair. The patient had torn their shoulder cuff and needed to have the muscle reattached and anchored down. This is a fairly routine procedure the only thing that changes seems to be the technology used for the operation. This was particularly evident when the tools Dr. Warren requested were not present and we had to wait for the nursing staff to bring the equipment Dr. Warren liked using to sow the muscles together.

Here are some images of what shoulder arthroscopy looks like.

What you see on the outside:

What the doctor sees on the screen:

Images provided by by Mr Hamid G. Zadeh

Wednesday, July 27, 2005

Clarissa - 7/27/2005 - SOAP

After the first surgery of the day (a renal artery endarectomy to remove plaque and restore proper function to the kidneys), one of the residents sat down with a third-year medical student and I and ran through one of the basic procedures conducted before an operation (SOAP), as follows:

Subjective
The initial portion of the SOAP format consists of subjective observations, usually symptoms the patient verbally expresses to the medical assistant or a family member. This can include (but are not limited to) patient descriptions of pain, discomfort, nausea, dizziness, etc.

Objective
The objective observations include symptoms that can actually be measured, seen, heard, touched, felt, or smelled. The vitals signs (pulse, blood pressure, max temperature, respiration, skin color, swelling) are major observations. Monitoring of fluids are also very important and include intravenous inputs, liquid/food intake, fluids lost from urine and blood, and emesis (vomiting). The assessment of skin is important to locate ulcers and lesions, especially in bed-ridden patients. The eyes must be round and reactive, and visual acuity can also be tested. The head-ears-nose-throat (HENT) is another diagnostic test system that makes sure the dentition (teeth) are okay, the tonsils are not inflamed, the uvula is midline, the trachea is midline, and that there are no abnormal nodes in the neck/throat area. The torso is also inspected for scars, abnormalities in shape, symmery, palpations, and other symptoms. The carotids are felt for pulses and listened to for bruits (which indicate blockage). The heart is checked for the rate and also for any irregularities. A variety of other diagnostic tests are also performed in a thorough SOAP exam.

Assessment
Following the objective observations, a diagnosis of the patient's condition is given. Occasionally, the diagnosis is very clear, but often, the assessment may not be clear and could include several possibilities.

Plan
The last part of the SOAP may include laboratory and/or radiological tests ordered for the patient, medications prescribed, treatments performed (minor surgeries), patient referrals to a specialist, patient disposition (home care, bed rest, days excused from work, hospital admission, etc), patient directions and follow-up directions.

There were several surgeries performed by Dr. Faries and Dr. Bush today, however, the one that seemed to glean the most attention was the axillobifemoral bypass surgery coupled with an open AAA (abdominal aortic aneurysm) repair. The patient is HIV+ with hepatitis and a long history of drug abuse. The bypass will be conducted first, using a PTFE (teflon-like synthetic graft) that will run superficially (under the skin). The two surgeries were initially scheduled for separate days, but a CT scan showed that the aneurysm had grown from 2.3 cm to 5.7 cm in only a matter of weeks, and a contained rupture in the AAA had occurred. The surgery, which is currently ongoing, is extremely high-risk and expected to exceed 12 hours and carry on well into the night.

An axillobifemoral bypass becomes necessary when a blockage or narrowing of the arteries supplying the legs with circulation becomes so severe that constant pain, as well as the risk of ulcers or gangrene, is present. The operation seeks to bypass the blocked arteries in the abdomen that supply the legs, so that the circulation is improved.

Robotic Assisted Nerve-sparing Radical Retropubic Prostatectomy

Last week I observed this surgery performed by Dr. Tewari. It is a robotic assisted removal of the prostate without cutting nerves. It is the same procedure that can be seen by following the images here, only that since it is robotic assisted, it is not open surgery. The nerve sparing technique refers to attempting to avoid damaging of the nerves that could otherwise result in complications such as incontinence.

Basically, the prostate is removed by cutting the urethra above the external sphincter and below the bladder neck, and then these two sections are stitched together. Instead of opening the patient, small incisions are made in the abdomen through which instruments are inserted. In this case there were five incisions (see below), two are from the robot, one is for illumination inside the body, and two more are handled by two doctors assisting the main surgeon that controls the robot. The area inside the body is filled with CO2 in order to create a cavity to have room to work as well as to help suppress some bleeding. Here you can see a video of part of the procedure.



The main surgeon is looking into a machine that shows a 3D video image from inside of the body. The surgeon controls the robot using elaborate hand controls and pedals and assistants interchange the tools on the robot arms. The 2D and 3D video is also displayed throughout the room. If you notice from the video, there are two tools doing steady work, this is the robot, and two other tools holding things, these are the assistants. Also notice that smoke is emitted when a cut is made by the robot, this is because the tool heats up as it cuts in order to seal the blood vessels and prevent bleeding. In order to stitch together the urethra, a catheter is inserted through the penis to find the urethra that has been cut. The stitches are done with the robot and the prostate is removed from inside the body manually. Here I got a feel for how tough skin is. In order to pull out the prostate, one of the surgeons stuck his fingers in the cut and pulled it apart hard to open it up a bit more. It seemed like the pull would have tore the skin but it actually had little effect.

The whole procedure takes about an hour and the patient goes home the same day. Amazing.

-Diego

Tuesday, July 26, 2005

Clarissa - 7/25/2005 and 7/26/2005 - Below-Knee Amputation and Osteomyelitis

Monday was spent intermittently on the OR floor, watching various surgical procedures, namely an open carotid endarectomy and a below-knee amputation. Tuesday was clinic day, down in the Cornell Surgical Associates clinic, mostly seeing patients with Dr. Bush and one of the residents. A good number of the patients were post-op check-ups, but there were a couple more interesting cases. Also, a moderate amount of time was spent searching for articles online in the Journal of Vascular Surgery. After discussing with Dr. Bush, we have decided a term paper topic: "The History of Treatment for Abdominal Aortic Aneurysms".

Below Knee Amputation

Going into an amputation surgery, I was amazed at the precision and the complexity involved in such an operation. Initially, I had the impression that the procedure would be fairly simple, something resembling a chopping block of sorts, where the patient would be in and out in half an hour. The patient had received a kidney transplant that failed and caused complications in the circulation of one of his legs. This leg then became gangrenous and needed to be amputated below the knee so as to prevent the spread of infection and tissue necrosis.

After the patient was prepped and ready, the tissue around the site of incision was cut down to the bone circumferentially, leaving a flap of skin and fat. This extra flap would serve as padding by covering up the site of amputation. Some of the major blood vessels were clipped off for later cauterization and/or tying off. Using an electric saw, the tibia and the fibula were cut by applying pressure steadily. After the foot/leg was removed from the surgical table, the remaining vessels were cauterized or tied off, and the remaining flap was sutured around the stump so as to form a cushion. The amputated leg was then placed in a red biohazard bag and sent to pathology for further testing.


Osteomyelitis

Osteomyelitis is a chronic bone infection, usually caused by bacteria, in which the bone tissue dies as a result of lost blood supply from swelling or infection. People at high risk for this disease include those with diabetes, hemodialysis, intravenous drug abuse, spleen removal, or recent trauma. Symptoms include bone pain, local swelling and redness, nausea, general discomfort, or drainage of pus through the skin.

Tissue-Equivalent Phantoms

Synthetic materials have been developed for invitro research of the effects of radiation on human tissue. These materials are known as tissue-equivalent phantoms and can be designed to mimic the dielectric properties of different tissues. The best studied phantom models that I have come across were first developed by Arthur Guy in 1971. In my case, I am looking into the effects of microwave radiation on the prostate from transurethral microwave theremotherapy (TUMT) devices.

Guy (1971) has developed tissue-equivalent phantom models specifically for preclinical studies of the effects of microwave radiation on human tissue. Based on Guy’s methods, Chou and coworkers (1984) published formulas for preparing tissue-equivalent phantom models with similar dielectric properties of muscle tissue at specific frequencies, including 915 MHz that commonly used in Transurethral Microwave Thermotherapy (TUMT) devices. This and similar methods have since been used by several groups including FDA Premarket Approval preclinical studies conducted by the device manufacturers in studying the heating profiles of TUMT devices.

In case this is useful to anyone, the references below are good resources for developing your own custom phantoms.

-Diego

1.      Guy AW, Analyses of Electromagnetic Fields Induced in Biological Tissues by Thermographic Studies on Equivalent Phantom Models. IEEE Transactions on Microwave Theory and Techniques. MTT-19 (2): 205-214, 1971

2.    Chou CK, Chen GW, Guy AW, Luk KH. Formulas for Preparing Phantom Muscle Tissue at Various Radiofrequencies. Bioelectromagnetics. 5: 435-441, 1984

3.      Land DV, Campbell AM. A quick accurate method for measuring the microwave dielectric properties of small tissue samples. Physics in Medicine and Biology. 37 (1): 183-192, 1992

4.      Dimofte A, Finlay JC, Zhu TC. A method for the determination of the absorption and scattering properties interstitially in turbid media. Physics in Medicine and Biology. 50: 2291-2311, 2005

5.      Gabriel C, Gabriel s. Compilation of the dielectric properties of body tissues at RF and microwave frequencies. Kings College, London. 1996. Accessed 7/26/05.

HAPPY BIRTHDAY ABHISHEK!!!

Monday, July 25, 2005

Hui 07/22/05

Unlike what you guys are working on, MR is a TOOL in clinique study. Thus I am not working on a specific disease yet but try to gathering knowedge of MRI in general.I have been looking through the book from Dr.Prince, MRI FROM Picture to Proton. Here is some summaries of what I have learned from the book.
MRI GENERAL 1
The concept for medical application of Nuclear Magnetic Resonance (NMR) wasn’t brought up until 1971, though NMR has been studied soon after the Second World War. In 1971 Raymond Damadian found that certain mouse tumors displayed elevated relaxation time compared to normal tissues, which may result in potential contrast between tissues and disease. Modern MRI is based exactly on this discovery.

As you may know, hydrogen atom is abundant in the human body in water and other molecules. The hydrogen atom is a continuously rotating positive charge, and their magnetization vector is randomly oriented. When a large external field is applied, each individual magnetization vectors will align either parallel (lowers energy state) or anti-parallel (highest energy state) to the field according to the Boltzman distribution, and the initial spin angular momentum of the particles causes their magnetization vectors precess around the axis of the applied external field in Larmor frequency, as a spinning top. However, at equilibrium the protons are all out of phase with each other. The sum of all these spins is called the net magnetization M0, which is aligned exactly with the main field B0 (around 1.5 tesla) , only of the order of microtesla, thus very difficult to be measured.

The spins can transfer from lower energy state to a higher energy state by a radiofrequency pulse with the larmor frequency. The RF pulse will flip Mo always from Bo toward the transverse plane and bring all spins into phase coherence. The flipped Mo will induce voltage change in the receiver coil, which is only sensitive to magnetization parallel to the transverse plane. Relaxation starts once the RF is turned off. Thus signal decays with the relaxation.

There are 2 main features of the relaxation: a dephasing of the spins and the realignment along the Bo as they lose energy. Dephasing is caused by mainly by inhomogenous main magnetic field. Another cause is the interaction between the spins, called spin-spin relaxation, characterized by relaxation time T2. On the other side, interaction between spin and its surrounding tissue---known as lattice, cause the spins lose energy and return to equilibrium state. This is called spin-lattice relaxation and characterized by relaxation time T1. In human tissues T1 is always longer than T2. The difference between T1 and T2 make it possible to take specific T1-weighted, T2-weighted or proton density images. Also different tissues have various T1 and T2 times. This is the key that forms contrast in MRI images.

To be continued...

Saturday, July 23, 2005

Abhishek - 7/24/2005

Hi all,

I am working in the Pediatric ICU with Dr. Pon and Dr. Frayer as my mentors.

First week -

In the first week I attended the everyday rounds with Dr. Pon and his residents and fellows, in the morning from 8:00-10:00AM. To be frank, coming from an Electrical Engineering bacground, I was quite overwhelmed by the jargon used by the Doctors while attending to the patients. Dr. Pon suggested me carrying a small book, making notes of all the words I didn't understand and at the end of rounds he would sit with me and clear all my doubts and go patient to patient if needed and explain their conditions at length.

The first week I concentrated on the technology used in monitoring equipments in the ICU. The one machine which I found very intriguing was the Ventilator which is used to assist the patient to breathe through the mouth. The ventilator has 2 tubes - one for providing air and the other for removing the exhaled air. The air being inhaled is supplied with a set amount of Oxygen thus having control on the intake of the patient. One tube connected to the inhale and exhale tubes is taken in to the mouth and placed in the trachea of the patient. I have learnt that the placement of the tube in the patient comes from experience. Dr. Pon showed me that if the placement of the tube in the trachea is not snug then the patient would breathe pushing air out of his mouth and not through the exhale tube. This can be detected by placing a stethoscope close to the patient's mouth and checking if the air is coming out of the patient's mouth. I learnt about the different modes of the Ventilator such as PC, VC, APRV, SIMV etc. and how the usage depends on the patient's condition. Currently the PICU is evaluating the pros and cons of ventilators from 2 different companies.

Another equipment that I learnt about was the Pulse Oximeter. This device measures the Oxygen saturation in blood. This device is usually clipped on to the toe of the patient. It emits 2 light at 2 wavelengths and measures the absorption of the wavelengths by the Oxygen in the blood. For a normal patient it has to be close to 100%. This equipment has a lot of motion artifacts associated with its output and also its contact with the skin is a very important factor for good signal.

Second week -

In the second week I started attending surgeries. I attended 3 surgeries at the Urology department - Robotic prostate removal, Laproscopic Nephrectomy and Laser burning of the prostate. The Robotic prostate removal surgery was the most interesting one of them all. 4 incisions are made in the abdomen of the patient and 4 probes - one of the camera, one for manual control (if needed) and 2 for the robotic operating arms. The robotic arms have 4 degrees of motion - 3 xyz and 1 rotation. The surgeon sits in a remote location with his head down looking a 3D image seen by the camera. He has control over the focus of the camera. The surgeon has gloves to wear on his hands with which he used to move the 2 robotic arms. It was amazing to see how skilled the surgeon was who perform this surgery and also the ease at which they go about suturing the Urethra to the Urinary bladder.

I attended another surgery where a FONTAN procedure was performed on a 2 year old. It was an open heart surgery. One of the equipments used in the operation was the Bypass machine used to pump the heart externally while the surgery is being performed. I am currently learning about this procedure and will share with you the details of it in my next blog.

-Abhishek

Friday, July 22, 2005

Tunde - 2nd week posts

Thursday ---> July 21st
Today, we had the honor of shadowing Dr. Potter (Chief of the Division of Magnetic Resonance Imaging)through her morning readings. During this experience, we learnt alot about the different types of MRIs including T1 and T2 weighted images, Spin density images and Fat suppresion techniques. We also actually got to see an MRI being taken using the Fat suppression technique. This, as explained by Dr. Potter and one of her technicians, can be done because the frequencies at which Fat and Water are read are about 250Hz apart, thus allowing the techinician to suppress the wavelengths read from fat (which are the always higher and more intense than that read from water).
In addition, through several readings, we had the opportunity to learn about discerning several orthopedic diseases and conditions using MRI images such as particulate disease, stress fractures, osteoporosis, rheumatoid arthritis and osteoarthritis.

Friday ---> July 22nd
Upon request, we got to observe a spinal surgical procedure with Dr. Sama. He performed a Laminectomy on a patient who complained of pain when trying to stand tip-toed. Upon viewing the patient's X-ray and MRI images, he found that the were some nerves being pinched by one of his lower vertebrae; L4 and L5 (Lumbar vertebraes 4 and 5).
By definitition, Laminectomy is a surgical procedure that is performed to alleviate pain caused by neural impingement(http://www.spinehealth.com). It is designed to remove a small portion of the bone over a nerve root (a nerve which branches off the dura nerve coming from the base of the brain) and/or disc material from under the nerve root to give the nerve root more space and a better healing environment.
Due to the abnormal anatomy of this patient, Dr. Sama found that instead of the nerve branching below the vertebrae, it had branched above, running under the pedicle of the 5th lumbar vertebrae, being pinched in the process. Thus the cause of pain and discomfort for the patient. So in this case, the pedicles of the 5th lumbar was removed to alleviate pressure on the nerves.

Clarissa - 7/22/2005 - Foot Debridement and Patch Angioplasty

In the morning, a foot wound debridement was performed by Dr. Bush to surgically remove dead tissue and bone from a previous partial foot amputation wound. Debridement is the process of removing non-living tissue from pressure ulcers, burns, and other wounds. Wounds that contain necrotic tissue heal more slowly, and could become colonized with bacteria, causing foul odors and inflammation, puttng a strain on the body's ability to fight infection. Necrotic tissue can often have abscesses, which are pockets of pus that can often lead from a general infection to amputation or death. Not all wounds require debridement, so the surgeon must rely on the patient's past medical history and other factors, such as blood flow to the wound region, to determine whether debridement is necessary.

The four major debridement techniques are: surgical, mechanical, chemical, and autolytic. Surgical debridement uses scalpels, scissors, or other cutting instruments to remove dead tissue from a wound, while repeated flushing the area with saline solution. In mechanical debridement, one of the oldest methods of debridement, a saline-moistened dressing is allowed to dry overnight and stick to the dead tissue. When the dressing is removed, the dead tissue is pulled away too, which can be very painful and also pull away healing tissue. Chemical debridement uses enzymes to dissolve necrotic tissue, which makes it more selective than the mechanical process. Autolytic debridement takes advantage of the body's own ability to dissolve dead tissue by keeping the wound moist with special dressings that trap wound fluids that promote healing. Though autolytic debridement is the most selective in ridding dead tissue, it is also the slowest process and is often inappropriate for certain wounds.

An open vein patch angioplasty was also performed in the morning by Dr. Bush. Stenosis in a vein causes restricted blood flow, and can lead to total occlusion. In a patch angioplasty procedure, the an incision is made in the vein at the point of stenosis, and a patch is placed over it, essentially making the vein "bigger" in diameter. The patch may be constructed from a piece of vein, artery, or synthetic material, trimmed to the appropriate size. See pictures below:






In the afternoon, another AAA endovascular stent placement (a popular procedure, it seems) was performed, which I shall detail in a later entry and/or my term paper.

Jeff Ballyns 2nd week blog

Tuesday: Satish, Tunde and myself sat in on a presentation on new methods for visualizing bone remodeling. The presentation was very dense but informative, however toward the later half of the presentation I found myself struggling to keep up with the methodology due to the large number of 3 letter acronyms being thrown around. 2 examples being EGR-1 and MAPK.

EGR-1 is called early growth response protein 1, which is a transcriptional regular that recognizes and binds to dna sequences. It can act like a tumor suppressor gene, with its expression repressed in breast carcinomas.

MAPK is called mitogen-activated protein kinases are part of a cellular method for inducing a response. MAPKs are involved in signaling a cascade of pathways to elicite a highly sensitive response.


I also finished reading Principles of MRI by Barry Friedman et al; 1989.


Wednesday: I Followed Devon, a lab tech in Dr. Susan Maher’s lab and observed a total knee surgery performed by Dr. Sculoco surgeon and chief at HSS. It was amazing to see how fast the operation was. We were there attempting to retrieve the meniscus for another research project but were unable to use the samples gathered since they were badly burned by the cotorizer. Dr. Sculoco then showed us some of the bone cement so we could observe and feel the chemical exothermic reaction, of how the cement got really hot as it hardened in our hands. Finally Devon showed me how they make the PGLA molds and we worked on some techniques on how to make a PVA micro-bead foam.



Thursday: I attended the arthroplasty meeting at HSS where they reviewed 3 cases. The 1st case was involving a medial tibia fracture with presence of OA. They decided to do a total knee operation, but needed to add an augmentation due to the severity of the displacement of the medial side of the tibia plateau. This was done so as not to cut the tibia to close to the fibula head. The 2nd case was a women who had had an Ostotomy earlier but had a fracture in her femoral condoles with cement progression down the femoral shaft due to a missing cement stopper. She had a total knee also with an added peg on the femoral condoles. The 3rd case was a dwarf in need of a hip replacement. The problem with dwarf cases is not only the small size but also the misshapen anatomy and the progressive problems with all leg joints in the body.

The next meeting I attended with Tunde was a discussion for the development of a model to predict the properties of the pelvis. Attending people were Dr. Potter, Dr. Wright, Professor Bartel and some HSS Surgeaons.

Lastly, Dr. Potter took us to her office to give us an introduction to reading MRI charts. One thing that amazed me more than how minute the details are that Dr. Potter has to observe when giving her prognosis of the patients injury is the amazing speed at which she is able to report her findings. Though much of the vocabulary I missed I was able to pick up on Ademia which is a swelling of the tissue. She also introduced us to various anatomy of the shoulder, hip and more on the knee.



Friday: Tunde and I were invited by Dr. Sama to observe a spinal surgery. The surgery consisted of removing the Spinous process of the 4th spinal vertebrae to relieve pressure on the nerves branching out from the durma (main spinal cord). Some of the interesting things they used included bone wax (actually bees wax) that aids in stopping bleeding by plugging up the site, gel gauss treated with thrombin which aids in preventing blood clotting. The entire surgery took 5 hours.

Thursday, July 21, 2005

Clarissa - 07/21/2005 - Aneurysms and Imaging Techniques

An aneurysm is defined as an abnormal widening or ballooning of a portion of an artery, related to weakness in the wall of the blood vessel. The most common locations for aneurysms include the aorta, the brain, the leg, the intestines, and the spleen. Aneurysms are either congenital or acquired. Although it is still largely unknown what specifically causes aneurysms, studies have shown that defects in some compotents of the artery wall may be responsible. In certain cases, such as abdominal aortic aneurysms (AAA), high blood pressure (hypertension) is believed to be a contributing factor.

The following diagram shows a typical abdomiinal aortic aneurysm:


Arteries are composed of proteins such as collagen and elastin, which help maintain and preserve the structure of the vessels despite long-term expsure to the large blood pressures. Recent studies propose that when the balance between protein synthesis and protein degradation is disturbed in certain parts of the artery, the arterial wall loses its structure and tends to be stretched by blood pressure. There are opposing, but equally convincing, theories about whether this imbalance is caused by an inability to synthesize protein or an excess of protein degradation.

The symptoms of aneurysms vary depending on the location of the aneurysm. If near the surface, swelling can often be detected. If deep within the body, aneurysms often go undetected unless it swells to a size where it becomes painful or ruptures. Often, aneurysms can go undetected with a physical exam, and are often accidentally discovered when scanning for other diseases (such as gall stones, etc). Duplex Doppler Ultrasound examinations and CT scans are often used to evaluate aneurysms.

The Duplex Doppler Ultrasound examines the blood flow in the major arteries and veins in the arms and legs with the use of ultrasound (high-frequency sound waves). The test combines Doppler ultrasonography, which uses audio measurements to "hear" and measure the blood flow and duplex ultrasonography, which provides a visual image. Some details about how the test is conducted can be found here.

CT (Computer tomography) scans uses a method of body imaging in which a thin x-ray beam rotates around the patient. The amount of x-rays that make it through the patient are measured by small detectors, which feeds into a computer that analyzes the data and uses special algorithms to construct a cross-sectional image. 3D models f organs can be created by stacking the individual image slices together.

The diagram here illustrates the CT scan procedure:


On another note, last night was quite the clinical experience from the "patient" perspective, which I'm sure Satish will gladly detail in this blog after the meds wear off...

Hui –MRI at Weill Medical College Wednesday 7/20/05

MRI is used before liver transplantation to check liver and other abdominal organs, and their blood vessels in liver donors. Several MRI cases we read today were to inspect the health state of the liver and measure the volume of the two liver lobes. The software we used is not so “intelligent”. Doctors have to outline the two parts of liver on every slice of liver image, then calculate the volume manually. I was told by Dr. Prince that there is a powerful software over at Columbia medical center, using which you only need to outline one single image, and the software will track down other image slices and calculate out the volume in 5 seconds.

The only time I can access the MR scanner is in the evening after 8:00pm, when the doctors have finished all their clinical scanning. I have been scanning phantoms and watching technicians scanning patients these days. Today students in Dr.Wang’s group also walked me through the process scanning a human body, including how to get patient prepared for scanning. I am in need of a volunteer!!! Any of you have a painful shoulder or knee and what to know why? I will scan you for free:)

Methods for treating BPH

Actually, BPH is not directly treated. The following methods are for treatment of the urinary tract symptoms secondary to BPH.


TreatmentBrief Description
Transurethral Prostatectomy (TURP)Scrape away prostate
Transurethral Microwave Thermotherapy (TUMT)Heats prostate
Transurethral Needle Ablation (TUNA)Use a needle to kill prostate with RF frequency
High Intensity Focused Ultrasound (HIFU)Heats prostate
Interstitial Laser Coagulation (ILC)Heats prostate
Laser ProstatectomyVaporizes prostate
Water Induced ThermotherapyHeats prostate
Intraprostatic injection therapy with ethanol or hyperosmolar sodium chlorideDehydrates cells
Transurethral Enzyme AblationAttack cells and xtracellular matrix
Alpha BlockersDecrease muscle tone


TURP is currently the most effective treatment although it is more prone to side effects such as possible sexual dysfunction and also requires anesthesia and hospitalization. The other treatments are less invasive and are performed in an out patient basis, however their efficacy is at best comparable to TURP and many of these treatments lack long term data.

-Diego

Wednesday, July 20, 2005

Clarissa - Tuesday 7/19 and Wednesday 7/20

TUESDAY 7/19/2005

Since Dr. Faries and Dr. Kent, two of the vascular surgeons, have taken a two-week summer vacation, the OR has been fairly inactive. On Tuesday, I spent time on the floor, following the residents/fellows as they went on their rounds, and in the clinic where Dr. Bush works on Tuesdays and Thursdays. I watched wound dressing of a patient who had an amputation of the right leg at the knee and a debridement of a portion of the left heel, where the tissue was dying due to vascular disease. The V.A.C. machine - an on-bed portable unit - was used as a vacuum pump to continously suck the air out of the wound at 125 mmHg. This type of wound dressing expedites healing, and is especially good for larger wounds where skin grafts are difficult, although it must be used on healthy tissue (hence the debridement to rid the heel of dead tissue). See here.

During rounds in the clinic, a variety of patients were seen. There were several cases of edema and swelling in the lower extremities due to vascular diseases. I learned that for arterial diseases, the patients should hang their feet off the bed for greater comfort, and for venous diseases, the feet should be propped above heart level (the toes above the nose, so to speak). Another patient had a case of varicose veins, which occurs when the leaky valves of the superficial veins causes buildup of pressure and blood, causing blood to pool and veins to become prominent and bumpy below the skin. There are a variety of reasons for varicose veins, which include genetics, trauma, and phlebitis (inflammation from clots which is often caused by pregnancy or obesity). See here. Contrary to the common belief, varicose veins are not caused by malnutrition or too much or too little of exercise.

There was a patient with a hypercoagulate state who had a suspected case of Buerger's Disease. The classic Buerger's Disease patient is a young male heavy-cigarette smoker. It is most common in the Orient, Southeast Asia, India, and the Middle East. The initial symptoms often include claudication (or pain induced by insufficient blood flow during exercise) in the limbs. See here. Another patient came in with an infection of the big toes from a pedicure two years ago. There was also a checkup done on an patient who recently underwent a carotid surgery.

WEDNESDAY 7/20/2005

After finally having my scrub credits application go through the system (on Monday), I was able to collect my own scrubs from the scrub machine on the OR floor. The scrub-in training instructor (Vicky) that I contacted earlier last week is currently not conducting training at Cornell, so I think I'll have to try and convince one of the residents or medical students to walk me through the training. The early-morning surgery performed by Dr. Bush was a carotid endarterectomy, which involved open surgery (as opposed to the less invasive stenting procedure). Making the decision of which of these procedures to perform depended on a variety of factors. Some issues taken into consideration included the amount of occlusion, the tortuosity of the carotid, the previous history of the patient (such as, prior endartectomies or radiation exposures to the neck). For more information of endarterectomies, see here.

The mid-morning surgery was an angiogram to determine the problem in a superficial femoral artery. The catheter was inserted downstick through the groin and down the right leg. The patient has had a left leg amputation and a history of diabetes and vascular disease. Some toes have previously been removed from the right foot of the patient, and the right leg must undergo an angiogram to determine the state of the arteries. Since the patient has diabetes and is at risk for kidney failures, the contrast dye normally used during X-ray imaging is high in iodine has the potential risk for causing the kidnes to shut down. Instead, Omniscan Gadodamide solution, a more expensive, less effective, but safer alternative, was used in this procedure. The Gadodamide solution was injected manually by the surgeon (in approximately 5 cc amounts), since the automatic system (MEDRAD Mark V ProVis) is programmed specifically for the regular contrast dye.

That's all for now, folks. Cheers.

Tunde - Wednesday 7/20/05

During a brief presentation, I was introduced to a different area of research relating to one of the extracellular matrix components of cartilage, Aggrecan.
Aggrecan (aka aggregating chondroitin sulphate proteoglycan)is one of the most widely studied proteoglycans. It represents up to 10% of the dry weight of cartilage (which is normally up to 75% water). Many individual monomers of aggrecan bind to hyaluronic acid to form an aggregate (it is this unit that is termed aggrecan). These aggregates are comprised of up to 100 monomers attached to a single chain of hyaluronic acid via link proteins.
Aggrecan is responsible for the compressive strength of cartilage due to the high negative charge that exisits on the aggregates of chondroitin and keratin sulfates. It's structure is similar to a brush used to wash bottles, with all the negatively charged molecules spanning the length of it. The aggrecan monomer has three globular domains G1, G2 and G3, and in between these lie two interglobular domains.
So, in diseases such as rheumatoid arthritis and osteoarthritis, there is a loss of aggrecan. Two major cleavage sites are present in the interglobular domain separating the G1 and G2 domains. Cleavage occurs by aggrecanase (enzymes responsible for cleaving aggrecan, even under normal activity). Other enzymes (such as matrix metalloproteinases) also induce cleavage at other sites. By far the major portion of aggrecan released appears to be cleaved by aggrecanase.
Serum concentrations of cartilage (and bone) macromolecules may also be useful in differenciating between different stages of RA and between patients with rapid and slow progressive disease.
It has also been found that cleavage of the chondroitin and keratin sulfates results in the shortening of the aggrecan monomer and a reduction in strain of about 52% when the molecule is stretched. This may help lead to understanding the mechanics involved in diseases state cartilage; relating specific enzymatic activity to mechanical integrity.

Tuesday, July 19, 2005

Satish - Tuesday-7/19

Today we spent a part of the morning watching a presentation of new molecular imaging techniques to observe cellular processes in vivo that can be useful for a variety of clinical applications. One in particular is osteogenesis imperfecta (OI). Also saw some new ideas looking at protein transcription and BMP-2.

OI is a genetic disease where the bones break very easily and often for no discernable reason. There are 4 types of the disease that vary in severity and clinical signs. OI is caused by a defect in the production of collagen, a one of the major proteins in connective tissue and extracellular matrix of bone, usually providing the main tensile strength. The collagen can be with reduced in amount, quality, or a combination of the two. The disease is not easy to diagnose just from clinical signs and lab tests looking at collagen and DNA are common. Using OI models, Dr. Mayer-Kuckuk has found ways to look at the molecular effects of drugs on the bones of these mice and monitor the expression of any implanted cells within the mouse. Eventually, it can be used to detect the molecular changes in vivo.


BMP-2 is bone morphogenetic protein, type 2. It BMP's are a family of proteins that have been implicated in osteoinduction and have started being used clinically to induce bone growth in the case of grafts and fracture healing, especially in critical non-unions.

welcome to weill medical campus

it was very nice to meet all of you and to hear you are doing well with your summer immersion course. the blog is a great way to share your experience with others in the course. writing also improves the clarity of your learning.

i like to thank diego for creating this blog. i look forward to reading your daily posts of new procedures, vocabularies, observations, reflections, ...

yi

Diego at Weill - Urology

Hello All,

I’m working in the Urology department in an outpatient clinic with Dr. Alexis Te, Dr. Ashutosh Tewari, and Dr. David Staskin. Dr. Te focuses on the development of new techniques for treatment of benign prostatic disorders in men as well as the evaluation and treatment of incontinence in men, Dr. Staskin focuses on evaluation and treatment of incontinence in women, and Dr. Tewari does robotic prostate surgery.

The days are generally composed of observing surgeries and smaller procedures in the morning then doing research in the afternoon. Since this is an outpatient clinic (the patients go home the same day they come in), the surgeries are minimally invasive or non invasive. So far I’ve observed a Laser Prostatectomy for opening of the urethra in cases of Benign Prostatic Hyperplasia . Basically, as men get older, their prostate enlarges and can start blocking the urinary tract. In this procedure, a 532 nm Yttrium Aluminum Garnet (YAG) laser operating at around 30-80 Watts is used to vaporize part of the prostate surrounding the urethral wall. The patient is sedated and given local anesthesia by injection into the prostate then a catheter is inserted into the penis. The catheter contains fiber optics to transmit the laser light and also to transmit images while in the urethra. The surgeon then maneuvers the device while looking at a TV screen and blasts away prostate with the laser. Throughout the process water is circulated through the urethra to cool and also remove pieces of tissue.

The best way to describe the way that the laser cuts is like a blowtorch through butter. The prostate tissue literally vaporizes and the room ends up smelling like burnt flesh.

Alternative techniques include scraping out the prostate with a sharp catheter tip (TURP), delivering microwaves to the prostate through an antenna in a catheter (TUMT), and using needles to penetrate the prostate and deliver RF frequencies to damage prostate tissue (TUNA). The advantage of the laser technique over these is that it produces minimal bleeding and is generally more effective in opening the urethral passage without heating other tissue.

Another surgery that I’ve observed is an Extracorporeal Shock Wave Lithotripsy. This technique employs high intensity focused ultrasound to break apart kidney stones without affecting other tissue. The surgery in non invasive; the surgeon basically ‘points and shoots’ by focusing in on the kidney stones using the same machine at lower ultrasound frequencies then delivering 2500 high intensity pulses. There is no sedation or anesthesia, only a relaxant is administered. The patient supposedly feels like she/he is being stuck by a rubber band in the kidney and is left with a bruise on their back where the machine makes contact. After treatment the kidneys stones are excreted through the urinary tract and the patient is given a strainer to collect the pieces of stones to send back in for a biopsy.

-Diego