CV Nurse

The Ross Procedure

noreply@blogger.com (myheart) — Thu, 06 Oct 2011 09:53:00 +0000

The Ross Procedure is a type of specialized aortic valve surgery where the patient's diseased aortic valve is replaced with his or her own pulmonary valve. The othera referenca this procedure is called switch procedure The pulmonary valve is then replaced with cryopreserved cadaveric pulmonary valve. In children and young adults, or older particularly active patients, this procedure offers several advantages over traditional aortic valve replacement with manufactured prostheses.

History

The Ross procedure is named after Dr. Donald Ross - a pioneer in cardiac surgery in the UK - who proposed the procedure in 1962 and first performed it in 1967.

Indications

Hypoplasia of the aortic valve annulus in the neonate
Progressive stenosis of the aortic valve in infants and children
Multilevel left ventricular outflow tract obstruction in association with aortic valve stenosis not amenable to aortic valve repair that requires enlargement of the outflow tract
Aortic insufficiency as a complication of percutaneous balloon aortic valvuloplasty
Rheumatic aortic valve disease
Aortic valve endocarditis

Contraindications

Pulmonary valve pathology
Known genetic defects in fibrillin, elastin, or collagen in connective tissue disorders (eg, Marfan syndrome, Ehlers-Danlos syndrome)
Significant immune complex disease as a coexisting disease, especially if it is the etiology of the aortic valve disease. (eg, systemic lupus erythematosus, ankylosing spondylitis, Reiter disease)
Advanced 3-vessel coronary artery disease
Significant irreparable mitral valve pathology that requires mechanical valve replacement (considered a relative contraindication by many surgeons)
Significant dilatation of the aortic root in comparison to the pulmonary valve annulus associated with aortic regurgitation (considered a relative contraindication by many surgeons, whereas others may continue to offer the Ross procedure along with aortic annular reduction)

Advantages / Disadvantages
Advantages

Freedom from thromboembolism without the need for anticoagulation.
The valve grows as the patient grows (i.e. children).
Favourable hemodynamics.
No foreign material present in the valve.

Disadvantages

Single valve disease (aortic) treated with a two valve procedure (aortic and pulmonary).
Pulmonary valve replacement

Preoperative

Echocardiography is used preoperatively to assess the aortic valve pathology, levels of left ventricular outflow tract obstruction and associated cardiac abnormalities. The pulmonary valve is assessed for clinically significant regurgitation or any other pathology. Echocardiography is also useful for assessing the sizes of the aorta and pulmonary annulus. A disparity in size of more than 2-3 mm is likely to require augmentation or reduction in the diameter of the aortic annulus.

Procedures

All procedures are performed though midline sternotomy. Cardiopulmonary bypass is established via standard aortic and bicaval venous cannulation. The left ventricle is decompressed by venting through the right superior pulmonary vein. Mild hypothermia (32-34 º) is used with a combination of antegrade and retrograde cold blood cardioplegia. Antegrade cardioplegia is initially administered through the root and then by direct coronary artery cannulation at 20-minute intervals.
The aorta is transected 1.5 cm above the right coronary artery. The aortic valve is inspected and repaired, if possible. If the valve is not repairable, the leaflets are then completely excised and calcium is debrided if present. The main pulmonary artery is partially opened just proximal to the bifurcation, and the valve is inspected to ensure normal anatomy and function.
Once the decision is made to proceed with the Ross procedure, the coronary buttons are prepared. A generous rim of aorta is left around each ostium to allow for suturing to the pulmonary autograft later. The pulmonary artery is separated from the aorta up to the bifurcation and is completely divided. The autograft is harvested by placing a right-angled clamp through the valve and by bringing the tip through the infundibulum approximately 1 cm below the base of the cusps. The right ventricular outflow tract is then opened circumferentially using scissors. Once the dissection proceeds laterally, the left anterior descending artery and its first septal branch are at risk if meticulous dissection is not performed. Following harvesting of the autograft, retrograde cardioplegia is administered and small venous branches are cauterized or ligated in the bed of the harvested autograft.

Step 1: Measurement of the aortic and pulmonic valves

Step 2: The aorta and pulmonary artery are opened and the aortic and pulmonary valves are carefully inspected to determine if the Ross is an appropriate procedure.

Step 3: The diseased aortic valve is removed. Then, the pulmonary valve (autograft) is removed and placed in the aortic position.

Step 4: The autograft in sutured in place and the coronary arteries are re-attached.

Step 5: A pulmonary homograft is attached to the right ventricle outflow tract.

Step 6: The aorta is attached to the autograft and the pulmonary artery is attached to the homograft - the procedure is complete.

One of the main objections to the Ross procedure is the genesis of pulmonary valve disease in addition to aortic valve disease. Proponents have argued that biological valves implanted in the pulmonary position would be slow to develop dysfunction, and any dysfunction would be well tolerated due to the lower pressures in the right side of the heart. Survival of homografts in the pulmonary position is good (20-year freedom from reoperation of 80%), and homograft dysfunction is infrequently implicated in the observed morbidity and mortality.

Homografts (aortic or pulmonary) should be the replacement of choice; no other valve performed as well in the pulmonary position. Many homograft valves are sterilized with ethylene oxide or irradiation -- methods recognized to have deleterious effects on valve performance. The results of the pulmonary autograft procedure are likely to be superior with the use of fresh homograft valves.Today, cryopreservation is the method of choice for homograft preservation.

References :

Bahaaldin Alsoufi et al.2009.The Ross Procedure for treatment of Pediatric Aortic Valve Disease
Cleveland Clinic. Ross Procedure. October 2011.
University of Southern California.The Ross Procedure. October 2011.
Wikipedia. Ross Procedure. October 2011.

Other reference The Ross Procedur can look in Medscape

Barlow Mitral Valve Disease

noreply@blogger.com (myheart) — Thu, 25 Aug 2011 19:15:00 +0000

The syndrome of mid-systolic click accompanying a systolic murmur was first described in the late 1800s, but it was in the early 1960s that its association with mitral regurgitation was demonstrated by Barlow and colleagues using cine-ventriculography¹. Criley et al.² correctly identified the mechanism of the regurgitation as posterior leaflet prolapse due to excess leaflet motion, coining the phrase ‘mitral valve prolapse’. Carpentier and co-workers later characterized the surgical lesions resulting from the myxoid degeneration present in Barlow’s disease, which included leaflet thickening, large redundant leaflets, chordal elongation or rupture, and annular dilatation. As the myxoid degenerative process often affects the entire valve, patients with Barlow’s disease generally have complex valve pathology and dysfunction, which is most often multisegmental (i.e. involves more than one segment of the posterior or anterior leaflet).

Clinical Presentation

Figure 1: ((a) Transesophageal echocardiography 4 chamber view showing bileaflet billowing with prolapse, large valve size, and thickened leaflet, all hallmarks of Barlow’s disease. (b) Surgical view of the same valve shows thickened tall prolapsing leaflets with excess tissue. (c) Valve has been successfully repaired after ‘complex’ bi-leaflet plasty. Repairs of this nature can only be reproducibly undertaken by reference mitral surgeons – in nonreference settings this valve would generally be replaced.

Patients with Barlow mitral-valve disease are generally adults around the age of 50 years who have known for a long period of time, often decades, that they ‘have a murmur’. Often asymptomatic, patients may have been followed by an internist for years, and referral to a cardiologist and subsequently to a cardiac surgeon is usually triggered by the development of symptoms or signs such as atrial fibrillation, shortness of breath and fatigue, or echocardiographic documentation of ventricular or atrial enlargement, or a decline in ventricular function, often accompanied by varying degrees of pulmonary hypertension. Physical examination most often reveals the presence of a mid-systolic click and a mid to late systolic murmur, which reflects the timing of prolapse in the setting of excess tissue and chordal elongation without chordal rupture (i.e. flail leaflet)².

Echocardiographic Findings

Echocardiography is a sensitive tool in the differentiation of degenerative mitral valve disease. A striking feature of the patient with Barlow’s disease is the size of the valve apparatus – the leaflets are usually thick, bulky, elongated, and distended; the chords thickened and elongated, often mesh-like in nature; and the annulus dilated and enlarged, often times greater than 36mm in the intercommissural distance (Figure 1). The prolapse is often multisegmental, and involves both leaflets in up to 40% of patients³. The insertion of the posterior leaflet is often displaced toward the left atrium away from its normal insertion in the atrio-ventricular groove, creating a cul-de-sac at the base of the leaflet. The bodies of distended leaflet segments often billow above the plane of the annulus, and the margin of the leaflet segments prolapse in mid-systole in the setting of chordal elongation, or in early systole if chordal rupture has occurred. Calcification of the annulus and papillary muscles may be present. Real time three-dimensional echocardiography is allowing additional clarity of the segmental nature of the billowing, as well as prolapse, in Barlow’s disease^4,5,6 and may play a critical role in the preoperative work up of these patients in the future.

Surgical Considerations

The complexity of surgical lesions in Barlow mitral-valve disease is consistent with the echocardiographic findings (Figure 1). Lesions include excessively thick and billowing leaflet segments, chordal elongation and chordal rupture, calcification of the papillary muscles and/or annulus with chordae restriction, and severe annular dilatation with giant valve size. It is important that the cardiologist as well as the surgeon has an appreciation for these lesions, as the complexity of techniques required to achieve a successful repair then becomes obvious in this subset of degenerative mitral-disease patients. Dealing with excess tissue height is an important consideration to reduce the likelihood of postoperative systolic anterior motion. Repair of Barlow valves is thus more complicated and, in our experience, often requires multiple different techniques and 2–3 hours to remove all of the diseased tissue, and reconstruct the leaflets to a normal configuration³.

Table 1: Targeting referral pattern to optimize repair rates.

To achieve a Barlow repair, the surgeon therefore needs to be well versed with various advanced mitral repair techniques, such as extensive leaflet resection, sliding leaflet plasty, chordal transfer, neochordoplasty, commissuroplasty, annular decalcification and use of large annuloplasty rings. Patients with advanced forms of Barlow’s disease will therefore likely have a high probability of successful valve repair only if done in reference centers by mitral subspecialists (Table 1).

http://www.mitralvalverepair.org

Medicines for High Blood Pressure

noreply@blogger.com (myheart) — Sun, 14 Aug 2011 06:16:00 +0000

Several types of medicine are used to treat high blood pressure. Your health care provider will decide which type of medicine is right for you. You may need to take more than one blood pressure medicine.

Each type of blood pressure medicine listed below comes in different brand and generic names.

One or more of these blood pressure medicines are often used to treat high blood pressure:

Diuretics are also called water pills. They help your kidneys remove some salt (sodium) from your body. As a result, your blood vessels don't have to hold as much fluid and your blood pressure goes down.
Beta-blockers make the heart beat at a slower rate and with less force.
Angiotensin-converting enzyme inhibitors (also called ACE inhibitors) relax your blood vessels, which lowers your blood pressure.
Angiotensin II receptor blockers (also called ARBs) work in about the same way as angiotensin-converting enzyme inhibitors.
Calcium channel blockers relax blood vessels by stopping calcium from entering cells.

Blood pressure medicines that are not used as often include:

Alpha-blockers help relax your blood vessels, which lowers your blood pressure.
Centrally acting drugs signal your brain and nervous system to relax your blood vessels.
Vasodilators signal the muscles in the walls of blood vessels to relax.
Renin inhibitors, a newer type of medicine for treating high blood pressure, act by relaxing your blood vessels.

SIDE EFFECTS OF BLOOD PRESSURE MEDICINES

Most blood pressure medicines are easy to take, but all medicines have side effects. Most of these are mild and many of them will go away over time.

Some common side effects of high blood pressure medicines include:

Cough
Diarrhea or constipation
Dizziness or light-headedness
Erection problems
Feeling nervous
Feeling tired, weak, drowsy, or a lack of energy
Headache
Nausea or vomiting
Skin rash
Weight loss or gain without trying

Tell your health care provider as soon as possible if you have side effects or your side effects become severe or bothersome. Most of the time, he or she can change the dose of the medicine or time of day you take it to help reduce side effects.

Never change the dose or stop taking your medicines on your own. Always talk to your health care provider first.

OTHER TIPS

Taking more than one medicine may change how your body absorbs or uses a drug. Vitamins or supplements, different foods, or alcohol may also change how a drug acts in your body.

Always ask your health care provider whether you need to avoid any foods, drinks, vitamins or supplements, or any other medicines while you are taking blood pressure medicine.

References

Kaplan NM. Systemic hypertension: Treatment. In: Bonow RO, Mann DL, Zipes DP, Libby P, eds. Braunwald's Heart Disease: A Textbook of Cardiovascular Medicine. 9th ed. Philadelphia, Pa: Saunders Elsevier; 2011:chap 46.

Update Date: 6/10/2011

Updated by: David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

source : medline Plus

Smoking Linked to Raised Risk of Irregular Heartbeat, Study Finds

noreply@blogger.com (myheart) — Sun, 14 Aug 2011 05:52:00 +0000

Current smokers have double the risk of this serious health problem over those who never smoked

By Robert Preidt

FRIDAY, Aug. 5 (HealthDay News) -- Smoking increases the risk of developing a heart rhythm disorder called atrial fibrillation, a new study warns.
U.S. researchers reviewed data from more than 15,000 people, aged 45 to 64, who were followed for an average of 13 years, and found that there were 876 atrial fibrillation events during that time.
The risk of the abnormal heart rhythm was 1.32 times higher in former smokers and two times higher in current smokers, compared to people who never smoked, according to the report in the August issue of the journal HeartRhythm.
Atrial fibrillation "is a serious health issue that decreases quality of life and significantly increases the risk of stroke," co-author Alanna M. Chamberlain, of the department of health sciences research at the Mayo Clinic in Rochester, Minn., said in a journal news release.
About 160,000 new cases of atrial fibrillation are diagnosed each year in the United States. Previous research has identified a number of risk factors for atrial fibrillation, including obesity, high blood pressure and diabetes.

SOURCE: HeartRhythm, news release, Aug. 2, 2011

HealthDay

Coronary Artery Bypass (CABG) Surgery

noreply@blogger.com (myheart) — Mon, 14 Feb 2011 04:07:00 +0000

The Heart Valves

noreply@blogger.com (myheart) — Sun, 13 Feb 2011 10:36:00 +0000

Four valves regulate blood flow through your heart:

The tricuspid valve regulates blood flow between the right atrium and right ventricle.
The pulmonary valve controls blood flow from the right ventricle into the pulmonary arteries, which carry blood to your lungs to pick up oxygen.
The mitral valve lets oxygen-rich blood from your lungs pass from the left atrium into the left ventricle.
The aortic valve opens the way for oxygen-rich blood to pass from the left ventricle into the aorta, your body's largest artery, where it is delivered to the rest of the body.

Reference :

1. Texas Hearth Institute

Heart Anatomy

noreply@blogger.com (myheart) — Sun, 13 Feb 2011 09:38:00 +0000

The heart weighs between 7 and 15 ounces (200 to 425 grams) and is a little larger than the size of your fist. By the end of a long life, a person's heart may have beat (expanded and contracted) more than 3.5 billion times. In fact, each day, the average heart beats 100,000 times, pumping about 2,000 gallons (7,571 liters) of blood.

Your heart is located between your lungs in the middle of your chest, behind and slightly to the left of your breastbone (sternum). A double-layered membrane called the pericardium surrounds your heart like a sac. The outer layer of the pericardium surrounds the roots of your heart's major blood vessels and is attached by ligaments to your spinal column, diaphragm, and other parts of your body. The inner layer of the pericardium is attached to the heart muscle. A coating of fluid separates the two layers of membrane, letting the heart move as it beats, yet still be attached to your body.

Your heart has 4 chambers. The upper chambers are called the left and right atria, and the lower chambers are called the left and right ventricles. A wall of muscle called the septum separates the left and right atria and the left and right ventricles. The left ventricle is the largest and strongest chamber in your heart. The left ventricle's chamber walls are only about a half-inch thick, but they have enough force to push blood through the aortic valve and into your body.

References :

1. Texas Hearth Institute

Who is Perfusionist ?

noreply@blogger.com (myheart) — Fri, 28 Jan 2011 14:39:00 +0000

Sometimes cardiovascular surgeons can operate on the heart when it is beating, but often they need to have it still. To maintain blood flow to the body’s tissues during operations when the heart needs to be stopped, surgeons call on perfusion technologists (often referred to as the “pump team”).

Perfusionists are vital members of the cardiovascular surgical team because they are responsible for running the heart-lung (cardiopulmonary bypass) machine. The heart-lung machine diverts blood away from the heart and lungs, adds oxygen to the blood, then returns the blood to the body—all without the blood having to go through the heart. During surgery, perfusionists use the heart-lung machine to maintain blood flow to the body’s tissues and regulate levels of oxygen and carbon dioxide in the blood. Perfusionists are also responsible for measuring selected laboratory values (such as blood cell count) and monitoring circulation. Under the direction of the anesthesiologist and surgeon, perfusionists may also administer medicines through the cardiopulmonary bypass circuit.

References :

1. Texas Heart Institute.

Surgery Team

noreply@blogger.com (myheart) — Fri, 21 Jan 2011 04:20:00 +0000

Each person involved in your surgery plays a vital role. Your surgeon and his or her assistants perform the surgery. Several specially trained nurses support them. The anesthesiologist constantly monitors your anesthesia to help you sleep without pain. The perfusionist operates the heart-lung machine (if one is needed) that keeps your blood flowing. Your blood pressure, temperature, and breathing are constantly monitored during the surgery.

Your Surgical Team includes:

Surgeon
Assistant Surgeons
Cardiologist
Surgical Nurse
Perfusionist
Anesthesiologist
Scrub Tech or Nurse

Surgeon

Every attempt is made for you to meet your surgeon on the day of your preoperative visit. If that is not possible, we will schedule a more convenient time for you to meet and discuss your operation.

Cardiologist

During your visit, you will meet with your cardiologist, who will perform a preoperative physical exam, answer your questions and review your medications. Your cardiologist will order the appropriate tests and review screening tests. These may include cardiac catheterization, echocardiography, electrocardiography, chest X-ray, routine bloodwork and urinalysis. Your cardiologist will monitor your care throughout your hospital stay and will oversee your discharge.

Surgical Nurse

You will also meet your surgical nurse, who works under your surgeon's supervision. Your nurse will perform a limited exam, review your lab data, provide instructions for your surgery and schedule your arrival time on the day of surgery.

Perfusionist

During surgery, your perfusionist operates medical equipment, including the heart-lung machineand cell saver machine, making sure that all the equipment are running smoothly. Throughout your surgery, your perfusionist will manage your lungs and the flow of your blood using the heart-lung machine.

Anesthesiologist

During your preoperative visit, your will meet your anesthesiologist, who is specially trained to give you anesthesia. Anesthesia keeps you asleep and free of pain during surgery.

Scrub Tech or Nurse

Right before your surgery, your scrub tech or nurse will prepare the operating room's sterile area, surgical instruments and equipment. During your surgery, your scrub tech or nurse will be next to you, assisting the surgeons by passing instruments and making sure that everything goes smoothly.

Reference :

Cardiothoracic Surgery

Waves and intervals

noreply@blogger.com (myheart) — Fri, 14 Jan 2011 14:14:00 +0000

Schematic representation of normal ECG

Animation of a normal ECG wave.

Detail of the QRS complex, showingventricular activation time (VAT) and amplitude.

A typical ECG tracing of the cardiac cycle (heartbeat) consists of a P wave, a QRS complex, a T wave, and a U wave which is normally visible in 50 to 75% of ECGs. The baseline voltage of the electrocardiogram is known as the isoelectric line. Typically the isoelectric line is measured as the portion of the tracing following the T wave and preceding the next P wave.

Feature	Description	Duration
RR interval	The interval between an R wave and the next R wave is the inverse of the heart rate. Normal resting heart rate is between 50 and 100 bpm	0.6 to 1.2s
P wave	During normal atrial depolarization, the main electrical vector is directed from the SA node towards the AV node, and spreads from the right atrium to the left atrium. This turns into the P wave on the ECG.	80ms
PR interval	The PR interval is measured from the beginning of the P wave to the beginning of the QRS complex. The PR interval reflects the time the electrical impulse takes to travel from the sinus node through the AV node and entering the ventricles. The PR interval is therefore a good estimate of AV node function.	120 to 200ms
PR segment	The PR segment connects the P wave and the QRS complex. This coincides with the electrical conduction from the AV node to the bundle of His to the bundle branches and then to the Purkinje Fibers. This electrical activity does not produce a contraction directly and is merely traveling down towards the ventricles and this shows up flat on the ECG. The PR interval is more clinically relevant.	50 to 120ms
QRS complex	The QRS complex reflects the rapid depolarization of the right and left ventricles. They have a large muscle mass compared to the atria and so the QRS complex usually has a much larger amplitude than the P-wave.	80 to 120ms
J-point	The point at which the QRS complex finishes and the ST segment begins. Used to measure the degree of ST elevation or depression present.	N/A
ST segment	The ST segment connects the QRS complex and the T wave. The ST segment represents the period when the ventricles are depolarized. It is isoelectric.	80 to 120ms
T wave	The T wave represents the repolarization (or recovery) of the ventricles. The interval from the beginning of the QRS complex to the apex of the T wave is referred to as the absolute refractory period. The last half of the T wave is referred to as the relative refractory period (or vulnerable period).	160ms
ST interval	The ST interval is measured from the J point to the end of the T wave.	320ms
QT interval	The QT interval is measured from the beginning of the QRS complex to the end of the T wave. A prolonged QT interval is a risk factor for ventricular tachyarrhythmias and sudden death. It varies with heart rate and for clinical relevance requires a correction for this, giving the QTc.	300 to 430ms^{[citation needed]}
U wave	The U wave is not always seen. It is typically low amplitude, and, by definition, follows the T wave.
J wave	The J wave, elevated J-Point or Osborn Wave appears as a late delta wave following the QRS or as a small secondary R wave . It is considered pathognomic of hypothermia or hypocalcemia.

There were originally four deflections, but after the mathematical correction for artifacts introduced by early amplifiers, five deflections were discovered. Einthoven chose the letters P, Q, R, S, and T to identify the tracing which was superimposed over the uncorrected labeled A, B, C, and D.

In intracardiac electrocardiograms, such as can be acquired from pacemaker sensors, an additional wave that can be seen is the H deflection, which reflects the depolarization of the bundle of His. The H-V interval, in turn, is the duration from the beginning of the H deflection to the earliest onset of ventricular depolarization recorded in any lead.

source : en.wikipedia

ECG Leads

noreply@blogger.com (myheart) — Fri, 14 Jan 2011 13:48:00 +0000

The term "lead" in electrocardiography causes much confusion because it is used to refer to two different things. In accordance with common parlance the word lead may be used to refer to the electrical cable attaching the electrodes to the ECG recorder. As such it may be acceptable to refer to the "left arm lead" as the electrode (and its cable) that should be attached at or near the left arm. There are usually ten of these electrodes in a standard "12-lead" ECG.

Alternatively (and some would say properly, in the context of electrocardiography) the word lead may refer to the tracing of the voltage difference between two of the electrodes and is what is actually produced by the ECG recorder. Each will have a specific name. For example "Lead I" (lead one) is the voltage between the right arm electrode and the left arm electrode, whereas "Lead II" (lead two) is the voltage between the right limb and the feet. (This rapidly becomes more complex as one of the "electrodes" may in fact be a composite of the electrical signal from a combination of the other electrodes (see later). Twelve of this type of lead form a "12-lead" ECG

To cause additional confusion the term "limb leads" usually refers to the tracings from leads I, II and III rather than the electrodes attached to the limbs.

Placement of electrodes
Ten electrodes are used for a 12-lead ECG. The electrodes usually consist of a conducting gel, embedded in the middle of a self-adhesive pad onto which cables clip. Sometimes the gel also forms the adhesive. They are labeled and placed on the patient's body as follows:

Proper placement of the limb electrodes, color coded as recommended by the American Heart Association (a different colour scheme is used in Europe). Note that the limb electrodes can be far down on the limbs or close to the hips/shoulders, but they must be even (left vs right).^[15]

12 leads

Electrode label (in the USA)	Electrode placement
RA	On the right arm, avoiding thick muscle.
LA	In the same location that RA was placed, but on the left arm this time.
RL	On the right leg, lateral calf muscle
LL	In the same location that RL was placed, but on the left leg this time.
V₁	In the fourth intercostal space (between ribs 4 & 5) just to the right of the sternum (breastbone).
V₂	In the fourth intercostal space (between ribs 4 & 5) just to the left of the sternum.
V₃	Between leads V₂ and V₄.
V₄	In the fifth intercostal space (between ribs 5 & 6) in the mid-clavicular line (the imaginary line that extends down from the midpoint of the clavicle (collarbone)).
V₅	Horizontally even with V₄, but in the anterior axillary line. (The anterior axillary line is the imaginary line that runs down from the point midway between the middle of the clavicle and the lateral end of the clavicle; the lateral end of the collarbone is the end closer to the arm.)
V₆	Horizontally even with V₄ and V₅ in the midaxillary line. (The midaxillary line is the imaginary line that extends down from the middle of the patient's armpit.)

Additional electrodes

The classical 12-lead ECG can be extended in a number of ways in an attempt to improve its sensitivity in detecting myocardial infarction involving territories not normally "seen" well. This includes an rV4 lead which uses the equivalent landmarks to the V4 but on the right side of the chest wall and extending the chest leads onto the back with a V7, V8 and V9.

Limb leads

In both the 5- and 12-lead configuration, leads I, II and III are called limb leads. The electrodes that form these signals are located on the limbs—one on each arm and one on the left leg. The limb leads form the points of what is known as Einthoven's triangle.

Lead I is the voltage between the (positive) left arm (LA) electrode and right arm (RA) electrode:

I = L A - R A .

Lead II is the voltage between the (positive) left leg (LL) electrode and the right arm (RA) electrode:

I I = L L - R A .

Lead III is the voltage between the (positive) left leg (LL) electrode and the left arm (LA) electrode:

I I I = L L - L A .

Simplified electrocardiograph sensors designed for teaching purposes at e.g. high school level are generally limited to three arm electrodes serving similar purposes.

Unipolar vs. bipolar leads.

There are two types of leads: unipolar and bipolar. Bipolar leads have one positive and one negative pole. In a 12-lead ECG, the limb leads (I, II and III) are bipolar leads. Unipolar leads also have two poles, as a voltage is measured; however, the negative pole is a composite pole (Wilson's central terminal, or WCT) made up of signals from lots of other electrodes.In a 12-lead ECG, all leads besides the limb leads are unipolar (aVR, aVL, aVF, V1, V2, V3, V4, V5, and V6).

Wilson's central terminal VW is produced by connecting the electrodes, RA; LA; and LL, together, via a simple resistive network, to give an average potential across the body, which approximates the potential at infinity (i.e. zero):

Augmented limb leads

Leads aVR, aVL, and aVF are augmented limb leads (after their inventor Dr. Emanuel Goldberger known collectively as the Goldberger's leads). They are derived from the same three electrodes as leads I, II, and III. However, they view the heart from different angles (or vectors) because the negative electrode for these leads is a modification of Wilson's central terminal. This zeroes out the negative electrode and allows the positive electrode to become the "exploring electrode". This is possible because Einthoven's Law states that I + (−II) + III = 0. The equation can also be written I + III = II. It is written this way (instead of I − II + III = 0) because Einthoven reversed the polarity of lead II in Einthoven's triangle, possibly because he liked to view upright QRS complexes. Wilson's central terminal paved the way for the development of the augmented limb leads aVR, aVL, aVF and the precordial leads V1, V2, V3, V4, V5 and V6.

Lead augmented vector right (aVR)has the positive electrode (white) on the right arm. The negative electrode is a combination of the left arm (black) electrode and the left leg (red) electrode, which "augments" the signal strength of the positive electrode on the right arm:

Lead augmented vector left (aVL)has the positive (black) electrode on the left arm. The negative electrode is a combination of the right arm (white) electrode and the left leg (red) electrode, which "augments" the signal strength of the positive electrode on the left arm:

Lead augmented vector foot (aVF) has the positive (red) electrode on the left leg. The negative electrode is a combination of the right arm (white) electrode and the left arm (black) electrode, which "augments" the signal of the positive electrode on the left leg:

The augmented limb leads aVR, aVL, and aVF are amplified in this way because the signal is too small to be useful when the negative electrode is Wilson's central terminal. Together with leads I, II, and III, augmented limb leads aVR, aVL, and aVF form the basis of the hexaxial reference system, which is used to calculate the heart's electrical axis in the frontal plane. The aVR, aVL, and aVF leads can also be represented using the I and II limb leads:

Precordial leads

The electrodes for the precordial leads (V1, V2, V3, V4, V5 and V6) are placed directly on the chest. Because of their close proximity to the heart, they do not require augmentation. Wilson's central terminal is used for the negative electrode, and these leads are considered to be unipolar (recall that Wilson's central terminal is the average of the three limb leads. This approximates common, or average, potential over the body). The precordial leads view the heart's electrical activity in the so-called horizontal plane. The heart's electrical axis in the horizontal plane is referred to as the Z axis.

source : en.wikipedia

ECG graph paper

noreply@blogger.com (myheart) — Fri, 14 Jan 2011 13:40:00 +0000

One second of ECG graph paper

The output of an ECG recorder is a graph (or sometimes several graphs, representing each of the leads) with time represented on the x-axis and voltage represented on the y-axis. A dedicated ECG machine would usually print onto graph paper which has a background pattern of 1mm squares (often in red or green), with bold divisions every 5mm in both vertical and horizontal directions. It is possible to change the output of most ECG devices but it is standard to represent each mV on the y axis as 1 cm and each second as 25mm on the x-axis (that is a paper speed of 25mm/s). Faster paper speeds can be used - for example to resolve finer detail in the ECG. At a paper speed of 25 mm/s, one small block of ECG paper translates into 40 ms. Five small blocks make up one large block, which translates into 200 ms. Hence, there are five large blocks per second. A calibration signal may be included with a record. A standard signal of 1 mV must move the stylus vertically 1 cm, that is two large squares on ECG paper.

source : en.wikipedia

ECG History

noreply@blogger.com (myheart) — Fri, 14 Jan 2011 13:38:00 +0000

Alexander Muirhead is reported to have attached wires to a feverish patient's wrist to obtain a record of the patient's heartbeat while studying for his Doctor of Science (in electricity) in 1872 at St Bartholomew's Hospital. This activity was directly recorded and visualized using a Lippmann capillary electrometer by the British physiologist John Burdon Sanderson.The first to systematically approach the heart from an electrical point-of-view was Augustus Waller, working in St Mary's Hospital in Paddington, London.[7] His electrocardiograph machine consisted of a Lippmann capillary electrometer fixed to a projector. The trace from the heartbeat was projected onto a photographic plate which was itself fixed to a toy train. This allowed a heartbeat to be recorded in real time. In 1911 he still saw little clinical application for his work.

Einthoven's ECG device

An initial breakthrough came when Willem Einthoven, working in Leiden, Netherlands, used the string galvanometer that he invented in 1903. This device was much more sensitive than both the capillary electrometer that Waller used and the string galvanometer that had been invented separately in 1897 by the French engineer Clément Ader. Rather than using today's self-adhesive electrodes Einthoven's subjects would immerse each of their limbs into containers of salt solutions from which the ECG was recorded.

Einthoven assigned the letters P, Q, R, S and T to the various deflections, and described the electrocardiographic features of a number of cardiovascular disorders. In 1924, he was awarded the Nobel Prize in Medicine for his discovery.

Though the basic principles of that era are still in use today, there have been many advances in electrocardiography over the years. The instrumentation, for example, has evolved from a cumbersome laboratory apparatus to compact electronic systems that often include computerized interpretation of the electrocardiogram.

source: en.wikipedia

ECG

noreply@blogger.com (myheart) — Fri, 31 Dec 2010 10:40:00 +0000

Electrocardiography (ECG, or EKG [from the German Elektrokardiogramm]) is a transthoracic interpretation of theelectrical activity of the heart over time captured and externally recorded by skin electrodes. It is a noninvasive recording produced by an electrocardiographic device. The etymology of the word is derived from the Greek electro, because it is related to electrical activity, cardio, Greek for heart, and graph, a Greek root meaning "to write". In English speaking countries, medical professionals often write EKG (the abbreviation for the German word elektrokardiogramm) in order to avoid confusion with EEG.

The ECG works mostly by detecting and amplifying the tiny electrical changes on the skin that are caused when the heart muscle "depolarizes" during each heart beat. At rest, each heart muscle cell has a charge across its outer wall, or cell membrane. Reducing this charge towards zero is called de-polarization, which activates the mechanisms in the cell that cause it to contract. During each heartbeat a healthy heart will have an orderly progression of a wave of depolarisation that is triggered by the cells in the sinoatrial node, spreads out through the atrium, passes through "intrinsic conduction pathways" and then spreads all over the ventricles. This is detected as tiny rises and falls in the voltage between two electrodes placed either side of the heart which is displayed as a wavy line either on a screen or on paper. This display indicates the overall rhythm of the heart and weaknesses in different parts of the heart muscle.

Usually more than 2 electrodes are used and they can be combined into a number of pairs (For example: Left arm (LA), right arm (RA) and left leg (LL) electrodes form the pairs: LA+RA, LA+LL, RA+LL). The output from each pair is known as a lead. Each lead is said to look at the heart from a different angle. Different types of ECGs can be referred to by the number of leads that are recorded, for example 3-lead, 5-lead or 12-lead ECGs (sometimes simply "a 12-lead"). A 12-lead ECG is one in which 12 different electrical signals are recorded at approximately the same time and will often be used as a one-off recording of an ECG, typically printed out as a paper copy. 3- and 5-lead ECGs tend to be monitored continuously and viewed only on the screen of an appropriate monitoring device, for example during an operation or whilst being transported in an ambulance. There may, or may not be any permanent record of a 3- or 5-lead ECG depending on the equipment used.

It is the best way to measure and diagnose abnormal rhythms of the heart, particularly abnormal rhythms caused by damage to the conductive tissue that carries electrical signals, or abnormal rhythms caused by electrolyte imbalances.In a myocardial infarction (MI), the ECG can identify if the heart muscle has been damaged in specific areas, though not all areas of the heart are covered. The ECG cannot reliably measure the pumping ability of the heart, for which ultrasound-based (echocardiography) or nuclear medicine tests are used. It is possible to be in cardiac arrest with a normal ECG signal (a condition known as pulseless electrical activity).

source : en.wikipedia

Anatomy

noreply@blogger.com (myheart) — Mon, 13 Dec 2010 06:56:00 +0000

Interior view

noreply@blogger.com (myheart) — Mon, 13 Dec 2010 06:49:00 +0000

About Us

noreply@blogger.com (myheart) — Sat, 11 Dec 2010 05:25:00 +0000

My name is Muhammad Badrushshalih. I'm a nurse in National Cardiovascular Center Hospital " Harapan Kita " Jakarta. I was graduated from Nursing Faculty on Jenderal Soedirman University Purwokerto. I war born in Cirebon, 11 august 1987 and now life on Jakarta.

This web is about cardiovascular. I hope it's can help you to get some information about cardiovascular. You can contact us on nersbadroe@gmail.com or join on my facebook

Heart Anatomy - Interior View

noreply@blogger.com (myheart) — Sat, 11 Dec 2010 04:08:00 +0000

Maricopa