The Heart: An Incredible Electric Machine

A quick primer on the electrical system of the heart followed by two major breakthroughs in pacemaker technology this year.

A leadless, subcutaneous defibrillator makes the list of 5 biggest medical breakthroughs of the year.

Boston Scientific has begun marketing a FIRST-OF-ITS-KIND DEFIBRILLATOR after receiving FDA approval in September. The implantable device, which protects against sudden cardiac arrest, was developed by a California firm purchased by Boston Scientific and is expected to be a financial win for the Natick-based company. Unlike others on the market, the S-ICD does not touch the heart, instead sending electrical pulses to correct abnormal rhythms through wires implanted just beneath the skin.

http://bostonglobe.com/magazine/2012/10/27/biggest-medical-breakthroughs-year/pLJDenlFAN3XFwwsxfU7CI/story.html

No More Batteries: Piezoelectric Pacemaker Powered By The Heart

An experimental device converts kinetic energy from beating hearts into electricitythan can power a pacemaker, meaning the chance for no more batteries in the future, according to a talk at the American Heart Association’s Scientific Sessions 2012.

The study is preliminary but a piezoelectric approach is promising for pacemakers because they require only small amounts of power to operate. Batteries must be replaced every five to seven years, which is costly and inconvenient.  Piezoelectricity might also power other implantable cardiac devices like defibrillators, which also have minimal energy needs.

“Many of the patients are children who live with pacemakers for many years,” said M. Amin Karami, Ph.D., lead author of the study and research fellow in the Department of Aerospace Engineering at the University of Michigan in Ann Arbor. “You can imagine how many operations they are spared if this new technology is implemented.”

Researchers measured heartbeat-induced vibrations in the chest. Then, they used a “shaker” to reproduce the vibrations in the laboratory and connected it to a prototype cardiac energy harvester they developed. Measurements of the prototype’s performance, based on sets of 100 simulated heartbeats at various heart rates, showed the energy harvester performed as the scientists had predicted — generating more than 10 times the power than modern pacemakers require. The next step will be implanting the energy harvester, which is about half the size of batteries now used in pacemakers, Karami said. Researchers hope to integrate their technology into commercial pacemakers.

Two types of energy harvesters can power a typical pacemaker: linear and nonlinear. Linear harvesters work well only at a specific heart rate, so heart rate changes prevent them from harvesting enough power.

In contrast, a nonlinear harvester, the type used in the study, uses magnets to enhance power production and make the harvester less sensitive to heart rate changes. The nonlinear harvester generated enough power from heartbeats ranging from 20 to 600 beats per minute to continuously power a pacemaker. Devices such as cell phones or microwave ovens would not affect the nonlinear device, Karami said.

http://www.science20.com/news_articles/no_more_batteries_piezoelectric_pacemaker_powered_heart-96003

 

End of Life Choices

For many with heart disease it is a battle to remain living, yet know you are dying from a diseased heart. Many don’t discuss with their healthcare practitioners the choices and decisions they have when it comes to fighting to stay alive or choosing to let go. Over my career I have watched many patients suffer trying numerous medical interventions and medications only to have a horrible quality of life. In the medical community we see patients literally beg their doctors to let them pass, and yet the physician urges them to fight on with the newest surgery or medication. These are issues that heart patients should be able to discuss with their families and health care providers early on, so everyone has a clear picture of your wishes.

When it comes to end of life you have choices

Your choices

• Stop treatment that prolongs your life. Instead, receive only treatment that focuses on your comfort and quality of life.

• Don’t stop treatment that prolongs your life.

Key points in making your decision

• If there is a good chance that your illness can be cured or managed, your doctor may advise you to first try available treatments. If these don’t work, then you might think about stopping treatment.

• If you stop treatment, you may still receive care that focuses on pain relief, comfort, and the quality of your life. This is called palliative care  or hospice care.

• A decision to stop treatment that keeps you alive doesn’t have to be permanent. You can always change your mind if your health starts to improve.

• Even though treatment focuses on helping you live longer, it may cause side effects that can greatly affect your quality of life and your ability to spend time with your family and friends.

• If you still have personal goals that you want to pursue, you may want treatment that keeps you alive long enough to achieve them.

Reasons to have life support:

•  You need life support because of an emergency that is not related to your illness.
•  Life support may help you return to your  normal activities.
•  Your quality of life is good and you have a sudden event that requires life support..
•  You could recover well from the event.

Reasons  not to have life support

• You have other long-term health problems that make it less likely that you will benefit from life support.
• The risks of life support outweigh the benefits.
• Life support will not help you return to your normal activities or to a level of activity you would like to have.
• You want a calm, peaceful death, and you do not want to spend the rest of your life on a ventilator

Physician Orders for Life Sustaining Treatment

I had a patient who wanted to die in cardiac rehabilitation. He expressed this wish often. He was adamant he did not want any life-sustaining treatment, however in rehab we were bound to comply with our standard of care which meant life-sustaining treatment, CPR and defibrillation until the patient was received in the hospital emergency room where his advanced directive were on file. This is the case in most hospital or outpatient settings, even EMS has an obligation to respond unless one has a POLST form visible in their house or on their person.   The only legal way for me to respect his wishes was for him to have a POLST form filled out and on file in the rehab department, and as a card he carried and a form posted in his home. What is POLST. It is an agreement made between  you and your physician about what life-sustaining treatment you with to have. To read more about this visit the link: http://www.ohsu.edu/polst/

Do you have an ICD?

Heart patients who have an ICD need to consider and  discuss the difficult issue of ICD deactivation as  clinical status worsens and death is near. Unfortunately, “clinicians and patients rarely engage in discussions about deactivating ICDs, and most devices remain active until death” and “most patients are not even aware that deactivation of the shocking function is an option.”

Palliative care relieves the symptoms of  disease, such as pain, shortness of breath, fatigue, constipation, nausea, loss of appetite and difficulty sleeping. It helps you gain the strength to carry on with daily life. It improves your ability to tolerate medical treatments. And it helps you have more control over your care by better understanding your choices for treatment options. Including decision-making and coordinating of issues such as ICD deactivation.

The point of palliative care is to relieve suffering and provide the best possible quality of life for both you and your family.

Palliative and hospice care is often left for the very end of life. By initiating palliative care earlier it reduces emergency department visits and improve symptoms, which increases time at home and quality of life.

Palliative Care
Palliative care teams are made up of doctors, nurses, and other professional medical caregivers, often at the facility where a patient will first receive treatment. These individuals will administer or oversee most of the ongoing comfort-care patients receive. While palliative care can be administered in the home, it is most common to receive palliative care in an institution such as a hospital, extended care facility, or nursing home that is associated with a palliative care team. There are no time restrictions. Palliative care can be received by patients at any time, at any stage of illness whether it be terminal or not.

Hospice

Hospice programs far outnumber palliative care programs. Generally, once enrolled through a referral from the primary care physician, a patient’s hospice care program, which is overseen by a team of hospice professionals, is administered in the home. Hospice often relies upon the family caregiver, as well as a visiting hospice nurse. While hospice can provide round-the-clock care in a nursing home, a specially equipped hospice facility, or, on occasion, in a hospital, this is not the norm. You must generally be considered to be terminal or within six months of death to be eligible for most hospice programs or to receive hospice benefits from your insurance.

Our health care system faces the challenge of allocating limiting resources to an aging population. The focus is on solutions that improve patient quality of life while minimizing unnecessary expenses.  Integrating palliative care into the health care system at an earlier time helps quality of life and reduced cost associated with the disease process.

http://www.getpalliativecare.org/whatis/faq

http://www.caregiverslibrary.org/caregivers-resources/grp-end-of-life-issues/hsgrp-hospice/hospice-vs-palliative-care-article.aspx

A lesson about the heart: Cardiac Output

Here is some information that is useful to know. It is a little in-depth when it comes to heart function, but I believe education is power and/or a sense of control when it comes to managing a chronic disease.  The more you know, the better you can work with your health care provider to help to manage it. 

Why are certain tests performed? An example is an echo is often performed 3-6 months following a heart attack. This allows the heart time for recovery and remodeling, and gives the healthcare provider a good idea of your cardiac output. Is your ejection fraction diminished, is the stroke volume lower thus decreasing the output? Is the cardiac output lower because the heart chamber is stretched, and weaker – inotropic effect, or due to medications? Does this place additional risk to you? When the ejection fraction is below 30% the risk for arrhythmia increases, thus precautionary measures such as Implanted Cardiac Defibrillators become an issue. Or vise versa if the heart function improved back to safe levels since the event there may no longer be the need, or those wearing external defibrillator vests may no longer be necessary.

The following came from Jewels of Clinical Medicine

What Is Cardiac Output?
Cardiac output is defined as the amount of blood pumped by the ventricles, the lower chambers of the heart, in one minute. Two factors determine cardiac output: stroke volume and heart rate. The equation used is: heart rate x stroke volume = cardiac output. A normal adult heart will have a cardiac output of approximately 4.7 litre( 5 quart) of blood per minute. Exercise will increase cardiac output, since it increases heart rate.

Heart rate
• The number of times the heart beats in one minute is the heart rate. In adults, the average heart rate is 60 to 100 beats per minute. Heart rates are usually higher in children and women. Differences in gender, size, age and fitness can affect the heart rate, as can some medications and conditions. Very fit people have lower resting heart rates. Heart rates increase when people are upset or excited.

Stroke Volume
• Stroke volume is the amount of blood pumped by the ventricles with each heartbeat. An average resting stroke volume is about 2 ounces (60 to 80 milliliters) per beat. Usually only 65 percent of the blood is pumped out of the ventricles during each beat. This is the normal ejection fraction value. Starling’s law of the heart and the inotropic effect are two things that can alter the force of the contraction, causing more of the blood to be expelled with each beat.

Starling’s Law of the Heart
• Starling’s law depends on the amount of stretch in the cardiac muscle fibers. If there is an increase in the volume of the blood pumped into the heart, that increase causes the ventricle to stretch, which in turn increases the force of contraction and the cardiac output. If less blood volume enters the heart, the ventricle does not stretch as much, the contraction is less forceful, and the cardiac output is decreased. This is important to ensure that the heart pumps out only what it receives at a given time.

Inotropic Effect
• If the strength of the contraction is increased without increasing the stretch of the cardiac fibers, cardiac output will be increased. Certain hormones and medications can cause this to happen. Sympathetic nerve stimulation of the heart, for example when a person is scared or excited, is another mechanism of the inotropic effect. Some drugs may also cause a negative inotropic effect and will decrease the cardiac output, which can lead to heart failure. It is extremely important to closely monitor the usage of any medication that has a negative inotropic effect on the heart.

Interesting Fact
• The amount of blood pumping though the body of the average adult is about 5 liters. That is equivalent to the average cardiac output. That means that the heart pumps the total amount of blood in the body every minute.

Heart Disease Health Centre- Dr.Yaseer SK

Choices in the care of your heart

Heart disease is challenging and frightful. Sometimes decisions are made very quickly regarding managing the disease process. Heart disease is a chronic condition that rears its ugly head over and over for many. As a heart patient  your best off having a good knowledge of the disease process and the choices of interventions.  Methods of intervention include:

• Angioplasty (balloon opening of artery)
• Cutting balloons and roto ruters
• Stent
• Drug eluting (coated) stent
• Open heart surgery – Bypass Surgery
• Treat medically with medicine and lifestyle
• Enhanced Eternal Counter pulsation therapy
• Left Ventricular Assistive Devices
• Heart Transplant

Many of these decisions are based on the amount of heart tissue that is involved. If there is a large region with insufficient blood flow caused by numerous blocked vessels you most likely will be recommended to have bypass surgery. The general rule is if three vessels are involved you will most likely require surgery. You do have choices though, as the main blockage can be intervened on through stents and the other vessels can be addressed at a later time. We call this staged stents. The  cardiologist do not  recommend placing stents to both the right and the left side of the heart during the same intervention. They will treat the culprit, and then come back later for the others.  The decision tree also takes into account what other issues (co morbidities) a patient has. If  a patient has end stage renal disease or their kidneys were severely affected by the heart problem then the physician my want to avoid treatments that place a heavy burden on the kidneys such as angioplasty or stents. They may opt to treat medically until the kidneys have recovered if they can.

A single vessel blocked will more likely be treated with a stent. However the location of blockage can be very challenging. If the blockage is  where the artery separates to another branch – called an anastamosis  these are very difficult to deal with because a stent would block the flow to the other artery. Sometimes they require surgery, new technology in stents is coming and these may be able to be stented in the future.  Some vessels are too torturous – meaning twisty and turny to allow a stent to be placed. Again surgery, treat medically  or EECP therapy would be considered.

Small vessels are less likely to be treated with stents and more likely to be treated with medications.  Medication includes nitro, long acting nitro, calcium channel blocker, ace inhibitors, beta blockers and occasionally EECP.

Intervention is determined by how viable the heart muscle is. If the heart muscle was severely damaged due to a heart attack  and now scarred over – or remodeled, further intervention to that region is not likely to be of any help.

EECP – it is enhanced external counterpulsation therapy. The therapy consists of cuffs wrapped around legs, calves and buttocks. When the heart finishes pushing the blood flow out, the cuffs sequentially inflate to push the blood back up the heart. By doing this the heart is somewhat engorged with blood and forms collateral vessels. The treatment consists of one hour treatments 5 days a week for 7-9 weeks.  Most patients find their frequency and intensity of angina is greatly diminished. Many patients hold the benefits for 2-5 years, but others will require more frequent return treatments to hold the gains. It is usually covered by insurance such as Medicare if the angina is considered functionally limited or disabling.  For some people with very serious heart damage this improves the pumping ability of the remainder of the heart muscle, as it becomes stronger due to increased blood flow from collateral arteries. The EECP alone will not maintain the benefits, you must still keep physically active through exercise to maintain the benefits.  The treatment is non invasive.

LVAD is a left ventricular assistive device.  These are used when the heart cannot meet the demands any longer to adequately circulate the blood. For many this is now considered a destination therapy. This means they will not be a candidate for a heart transplant but will forever rely on the mechanical pump to circulate their blood. These are becoming more frequently used, and the mortality rates are decreasing with these pumps. If your health care provider is contemplating this route for you, I would strongly suggest you contact support groups of patients who already have LVADS here is a Facebook link to such a support group.  https://www.facebook.com/pages/LVAD-Recipients/207915222572308

Heart transplants are necessary when the damage is such that the heart cannot meet the needs. Often the patient is repeatedly hospitalized in congestive heart failure. They are disabled due to the heart condition.

The take home is know the procedures, research the pro’s and con’s of each. Don’t walk in to the physician’s office and simply take the first suggestion. Question the efficacy, ask the probability of success and what are the limitations, what can you expect in the future. Be active in your healthcare. Most inpatient nurses will tell you they witness too many incidents where the health care provider tells the patient and family if you don’t do this you will die. Thus the patient feels compelled to have the intervention performed. You have choices.

Choices involve the above discussion, but also include risk factor modification every single day. Choose to exercise, choose to eat healthy, choose how to respond to stress, choose to take your medications,  choose to not smoke, choose to monitor blood sugar.

Bypass

Stent

Left Ventricular Assistive Device

 Enhanced External Counterpulsation Therapy

Prevention measures to avoid blood clots

Common issues following hospitalization include blood clots. Patients often wonder why we force them to get out of bed and move. Prevention of blood clots in the legs and lungs is critical for recovery

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Is my heart disease cured?

Many patients come through their heart procedures and feel they are cured. Unfortunately for most, heart disease is a chronic progressive disorder of the arteries in which deposits of cholesterol, calcium, and abnormal cells (that is, plaques) build up on the inner lining of the arteries.  Heart disease usually progressively deteriorates over time, whether due to normal bodily wear or lifestyle choices such as exercise or eating habits. This is a hard concept to grasp, and it doesn’t mean it is a death sentence either.

You can do everything right and still have further heart issues.

When patients struggle with this, I point out doing everything right may be why they survived, as approximately 50% of people do not survive their first heart attack.    It is so important for each person to know their body’s signs and symptoms and not ignore them. We don’t really know what makes coronary artery disease aggressive, there seems to be several factors. These factors include inflammation, c- reactive proteins, genetics, lifestyle to name a few. Some patients will have multiple issues for years requiring frequent interventions and then be fine for many years before having another issue. On average coronary artery bypass  grafts  10 years out will be 50% blocked. Some patients will go 20-30 years before needing another intervention, yet others may not even go a week or month before having symptoms. Thirty percent of open heart surgery patients will continue to have angina symptoms after surgery. The drug eluding stents have  much lower rates of re-stenosis than the bare metal stents which average 25-30% restenosis rates, but in both cases the vessels often continue to develop blockages in other locations in the artery. If the bare metal stents are going to re-stenos the usually do so in the first 3-6 months.  It is vital to stay on the platelet inhibitors – Plavix (clopidogrel) as prescribed to prevent complications.

Accepting the fact that you will have further heart disease is important.

Be on the lookout for new symptoms, for changes in energy patterns, note if you are becoming less active due to fatigue. Keep your risk factors in the best control possible. Try to get blood pressure, blood sugar, cholesterol numbers to national guidelines. Exercise regularly. Eat a rainbow of color in fresh fruits and vegetables each day. Don’t let stress effect your health, manage your stress as best as possible, consider counseling.  Don’t live in fear, live life to its fullest!!

Play hard.         Enjoy your families.

 Embrace life.          Do something rewarding every day.

Laugh.     Mentor others.   Love

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