DevicesForAgeingHearts

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Generic presentation on medical devices for ageing heart support

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Devices for ageing hearts:

Devices for ageing hearts Muraleedharan CV

Ageing:

The progressive ageing of the population is a phenomenon of our era . Number of people who are aged above 65 years is expected to increase by 150% in 2030. The incidence of cardiovascular diseases (CVD) increases linearly with age. More than 70% of the population over 75 years of age presents some clinically evident CVD . WHO (http://www.who.int/topics/ageing/en /) Ageing

Outline:

Outline Heart and circulatory system Working of heart Ageing processes in cardiovascular system Devices for management of ageing hearts Heart rhythm Valvular defects Coronary heart disease Congestive heart failure

Heart and Circulatory system:

Heart and Circulatory system

Human heart:

Human heart Every day, your heart beats about 100,000 times , sending 10,000 litres of blood surging through your body. Although it’s no bigger than your fist (with typical power rating less than 5 Watts), heart has the mighty job of keeping blood flowing through the 100,000 km of blood vessels that feed your organs and tissues. Any damage to the heart can reduce that pumping power, forcing the heart to work harder just to keep up with the body’s demand for blood.

Heart and circulatory system:

Heart and circulatory system Transport system of the body Blood as the media Oxygen / CO 2 Nutrients to cells Waste removal Heart acts as the pump Positive displacement pump Heart muscles – drive Rhythmic contraction and expansion of muscles controlled by electrical signals Blood vessels acts as the pathways – tubular structures

Heart - anatomy:

Heart - anatomy Has four chambers Two pumping chambers Four non return valves Two valves on either side Right side pumps through the lungs (pulmonary circulation) Left side pumps through the entire body (systemic circulation) Left heart & its valves are more susceptible to damage, since it works against the entire vascular resistance of systemic circulation

Blood vessels:

Blood vessels Arteries carry blood from the heart to various organs Transfer of oxygen, carbon dioxide and nutrients occur in the capillary network at various organs Veins collect the blood and returns to the heart for pumping again Blood flow controlled by the vessel resistances and pressure generated by the heart

Circulatory system - revisited:

Circulatory system - revisited LV RV LA RA 1 3 2 4 LUNGS BODY LA and RA are the collection chambers LV and RV are the pumping chambers Two valves, at the inlet and outlet of the pumping chambers Tricuspid valve Pulmonary valve Mitral valve Aortic valve

Working of heart:

Working of heart The natural pacemaker of the heart is the Sinoatrial (SA) node The electrical impulse leaves the SA node and travels to the right and left atria, causing them to contract together The electrical impulse subsequently reaches Atrio ventricular Node (AV node) and travels through the Bundle of His where it rapidly spreads using Purkinje Fibers to the muscles of the Right and Left Ventricle, causing them to contract at the same time

Heart : ageing & management :

Heart : ageing & management

Ageing - Electrical subsystem:

Ageing - Electrical subsystem The heart has a natural pacemaker system that controls the heartbeat. Some of the pathways of this system may develop fibrous tissue and fat deposits. The natural pacemaker (the SA node) loses some of its cells. These changes may result in a slightly slower heart rate.

Ageing – Electrical subsystem:

Ageing – Electrical subsystem Heart changes cause the ECG of a normal, healthy older person to be slightly different than the ECG of a healthy younger adult. Abnormal rhythms (arrhythmias) such as atrial fibrillation are more common in older people. They may be caused by heart disease.

Electrical subsystem complications:

Electrical subsystem complications When the natural conduction pathways does not perform correctly, or the natural pacing system fails, the heart does not beat at the appropriate rates In such cases, implantable pacemakers are used for regulating the cardiac rhythm Called ventricular resynchronization therapy

Pacemakers:

Pacemakers An electronic circuit senses the ECG and generates signals to resynchronize the heart rhythm. The heart rhythm is controlled to achieve the required heart rate; depending on the condition of the patient Provided with a battery (with typical 10 year life) and is totally implantable device

Pacemaker:

Pacemaker Antenna is used for external programming of the pacemaker subsequent to implantation

Ageing – heart valves:

Ageing – heart valves Normal changes in the heart include deposits of the "ageing pigment," lipofuscin. The heart muscle cells degenerate slightly. The valves inside the heart, which control the direction of blood flow, thicken and become stiffer. A heart murmur caused by valve stiffness is fairly common in the elderly

Heart valve defects:

Heart valve defects The heart valves, normally due to certain diseases or ageing, fail to function as unidirectional check valves; they either become too leaky in the closed state ( Regurgitation ) or very narrow and offer resistance to blood flow in the open state ( Stenosis ) Many modes of management are feasible for valvular defects – depending on the state of the valve and the patient LV RV LA RA 1 3 2 4 LUNGS BODY

Heart valve defects - management:

Heart valve defects - management Corrections : The state of the valve is improved, either using a catheter and balloon or using surgical intervention on valve using annulaoplasty rings Balloon expansion is employed in the case of stenosis Annularplasty rings are mostly for valve leaks Correction procedure cannot be performed in all cases Annularplasty ring

Artificial heart valves:

Tilting Disc Bileaflet Caged Ball Tissue Valve Artificial heart valves Artificial heart valves are devices used for replacing damaged or diseased natural valves of the heart. The natural valves are excised out and replacements are implanted Tissue valves Homorafts Xenografts Mechanical valves Caged ball Tilting disc Bileaflet

Ageing of cardiovascular system:

Ageing of cardiovascular system Receptors called baroreceptors monitor the blood pressure and make changes to help maintain a constant blood pressure when a person changes positions. The baroreceptors become less sensitive with ageing. This is why older people have orthostatic hypotension , a condition in which the blood pressure falls when a person goes from lying or sitting to standing position, causing dizziness.

Ageing of blood vessels:

Ageing of blood vessels With age, the capillary walls thicken slightly. This may cause a slightly slower rate of exchange of nutrients and wastes.

Ageing of blood vessels:

Ageing of blood vessels The arteries becomes thicker, stiffer, and less flexible, which is related to changes in the connective tissue of the blood vessel wall. This leads to high blood pressure and makes the heart work harder, which may lead to thickening of the heart muscle (hypertrophy). In general, most elderly people have a moderate increase in blood pressure.

Coronary heart disease:

Coronary heart disease Coronary arteries supply blood to the heart muscles Plaque deposition in arteries – lesions, inflammation Narrowing and reduction in blood flow causes ischemia, myocardial infarction (cardiac attack) Major killer disease in the world

Coronary heart disease - management:

Coronary heart disease - management Bypass surgery Plaque removal Plaque control by drug administration Angioplasty (PTCA) – catheter based Coronary Stenting – metal stent is deployed through a catheter

Coronary artery bypass grafting:

Coronary artery bypass grafting Patient’s own mammary artery or saphaneous veins are employed for grafting Synthetic grafts (tubes) developed till date are not very successful Researchers around the world are working to develop suitable small diameter synthetic grafts to replace coronary arteries Mammary artery grafting Saphaneous vein grafts

Plaque removal:

Plaque removal Catheter loaded with a diamond rotary blade 12,000 to 15,000 rpm rotation speed Debris generated may be collected using a collection system to eliminate the possibility of thrombus formation Yet, not very popular

PTCA:

PTCA Percutaneous Transluminal Coronary Angioplasty (PTCA), uses a balloon to open a clogged vessel The PTCA catheter is guided to the required site. When the balloon is inflated, this presses the plaque against the artery wall and opens up the lumen of the artery to achieve near normal blood flow Restenosis is the major failure mode

Coronary Stents:

Coronary Stents A type of wire mesh that fits within the artery. Inserted during the PTCA procedure When the balloon opens up to press the plaque against the artery wall, the stent opens up, too. Once the balloon is deflated and pulled out of the artery, the stent stays open and keeps the plaque in place Bare metal stents Drug eluting stents

Grafts for large blood vessels:

Grafts for large blood vessels When large diameter blood vessels (> 6 mm diameter) need to replaced, synthetic grafts are successfully employed Mainly two types Woven or knitted polyethylene terphthalate (PET) grafts Expanded poly tetra flouro ethylene (PTFE) grafts

Ageing – Muscular subsystem:

Ageing – Muscular subsystem A slight increase in the size of the heart, especially the left ventricle, is not uncommon. The heart wall thickens, so the amount of blood that the chamber can hold may actually decrease despite the increased overall heart size. The heart may fill more slowly.

Congestive heart failure:

Congestive heart failure Develops as a result of damage to the heart muscle Can occur following a heart attack or coronary artery disease Can also result from strain and pressure placed on the heart following years of untreated heart valve disease or high blood pressure

Congestive heart failure - management:

Congestive heart failure - management Cardiac support devices Intra aortic balloon pumps (IABP) Left ventricular assist devices (LVAD) Total artificial heart (TAH) Heart transplantation : a patient’s heart is replaced with a donor’s heart

Cardiac support devices:

Cardiac support devices Multi-filament yarn knit fabric support Provides ventricular support to reduce wall stress and myocardial stretch Reverses progressive dilation and improve cardiac function and patient functional status Mostly acts as bridge to recovery

Intra aortic balloon pumps - IABP:

Intra aortic balloon pumps - IABP IABP uses a balloon mounted on a catheter, which is inserted into the  aorta through the femoral artery in the leg The inflation and deflation of the balloon is synchronized to the heart’s pumping and is controlled from a console Balloon supports the heart indirectly, augmenting the blood flow

Left ventricular assist devices - LVAD:

Left ventricular assist devices - LVAD LVAD is a surgically implanted mechanical device that helps the heart pump blood Used as Bridge to heart transplantation Bridge to recovery permanent implants Three types Positive displacement Centrifugal pump Axial flow pump

LVAD - Designs:

LVAD - Designs Axial Flow Pump Centrifugal Pump

Total artificial heart - TAH:

Total artificial heart - TAH Natural heart is replaced with artificial twin pump Still in development stage Used only when Have end-stage heart failure. Have a life-expectancy of less than 30 days. Are not eligible for a natural heart transplant. Have no other viable treatment options

TAH Designs:

TAH Designs

Cardiovascular devices - Future:

Cardiovascular devices - Future Tissue engineering of cardiovascular devices offer immense opportunity Research in the area is in primitive stages One day world may see totally tissue engineered devices working in human heart …… but the day seems far away

Slide41:

Typically beats 3,000,000,000 times in person’s life time Any attempt by man to repair, augment, replace …. are only suboptimal till now and never performs like the one nature has created !! So, keep it well guarded.

Keep laughing:

Health experts now have proof that laughter is good for heart. A good laugh can send 20% more blood flowing through your entire body. One study found that when people watched a funny movie, their blood flow increased. That’s why laughter might just be the perfect antidote to stress. When you laugh, the lining of your blood vessel walls relaxes and expands. So have a good giggle. Your heart will Keep laughing Thank you

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