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  • Heart Failure
    • What is heart failure?

      Heart failure is a condition that results from the inability of the heart to pump blood effectively to the rest of the body. Heart failure itself is not a disease, but a manifestation which develops as a result of other conditions that damage/alter the characteristics of the heart.

      What are the causes of heart failure?

      » Heart attack

      » Coronary artery disease

      » Uncontrolled Hypertension/high blood pressure

      » Diseases of the heart valves

      » Diseases of heart muscle itself (cardiomyopathy)

      » Viral infections of the heart muscle (myocarditis)

      » Toxins that affect the heart muscle (such as some anti-cancer drugs)

      What are the symptoms of heart failure?

      Breathlessness on exertion, difficulty in breathing while lying down, swelling of the feet, face and other parts of the body due to accumulation of fluid, tiredness due to inadequate blood supply to the muscles, giddiness/ loss of consciousness and palpitations are the common problems a patient with heart failure faces.

      What are the consequences/complications of heart failure?

      Uncontrolled heart failure can be debilitating and life threatening.

      » Loss of productivity of a person

      » Renal failure due to low cardiac output

      » Dangerous Arrhythmias like Ventricular Tachycardia and Ventricular Fibrillation which could lead on to death

      » Atrial fibrillation which can put them at risk of a thrombo-embolic events resulting in stroke, gangrene etc.

      What is the medical management for patients with heart failure?

      Several studies have proven the benefits of various drugs in heart failure. These can be to reduce the pressure on the heart, increase the pumping capacity of the heart, to alter the hormone levels so that the blood pressure decreases and the heart can pump easily, to decrease the production of bad hormones, to relax the peripheral blood vessels, to make the kidney throw out the excess fluids and/ salts, and finally injections to temporarily increase the strength of the heart. There is active research in this field towards new drug discoveries.

      What are the other options available?

      First of all we treat the underlying cause of heart failure.

      For a valve problem we do valve repair/ replacement, for coronary artery blocks, we open the blocks by angioplasty or bypass operation, if there is any hormonal imbalance or drugs causing heart failure, we supplement the hormone or stop the toxic drugs and observe the heart for improvement. In case an infective etiology is suspected, we treat the same and reassess periodically for about 3- 6 months for spontaneous improvement.

      There are some invasive options like ECMO- which is a form of dialysis and we take out the excess water in the body using a machine with special filters.

      Next, there are special pacemakers to treat this condition. This is called cardiac resynchronization therapy/ CRT.

      If all else fail and the patient is an ideal candidate, he is enrolled for a Left Ventricular Assist Device implantation and further on cardiac transplantation.

      How can heart failure be managed by pacemaker?

      Pacemakers for heart failure are implanted by specially trained doctors dealing with electrical abnormalities of the heart. They are called Cardiac Electrophysiologists.

      A select group of patients with severe heart failure who are symptomatic despite optimal medical therapy and satisfy certain criteria like complete LBBB on the ECG, evidence of loss of synchrony between the various walls of the left ventricle on ECHO testing, are candidates who derive maximum benefit from cardiac resynchronization therapy/ CRT.

      In CRT, we place a wire in the right ventricle and another in the left ventricle in appropriate positions and try and make the walls of the enlarged left ventricle beat better and simultaneously. By doing so, the heart pumps as one unit and more blood is pumped into the aorta and the rest of the body.

      How can we make out that the CRT is effective?

      There are ECG parameters which show improvement like QRS width narrowing, improvement in the ejection fraction of the left ventricle and reduction in the severity of valve leak on ECHO and most importantly, the patient feels better and symptoms decrease significantly. Also these CRTs can be combined with internal defibrillators which give shock from inside the heart in case of ventricular arrhythmias and abort sudden death.

      These heart failure pacemakers have been shown in large trials to increase the longevity of the patient.

  • Atrial Fibrillation
    • What is atrial fibrillation (AF)?

      AF is a chaotic, disorganized, rapid beating of the upper chambers of the heart called the atria. When this happens, the heart rate increases and the cardiac output decreases causing symptoms. The upper chambers or the atrial rate is more than 350bpm and at this rate the contractions are ineffective thus referred to as fibrillating (tremor like).

      What are the manifestations of AF?

      Patients with long duration of AF could be asymptomatic and incidentally detected. More often people suffering from AF experience palpitations, dyspnea, fatigue, symptoms of heart failure, stroke/ TIA, giddiness/ LOC.

      As the heart rate is high and fast, patients feel it and due to decrease in blood supply to the body in general, patients experience fatigue and breathlessness on exertion.

      What are the risks associated with this arrhythmia?

      As there will be no effective contraction of the atrium, stagnation of blood in the chambers lead to increased risk of clot formation and stroke.

      Apart from the brain, these clots can embolise and block any artery resulting in serious consequences like limb loss/ loss of vision/ heart attack etc.

      People with a weak or very stiff hearts could develop water logging in the lungs called pulmonary edema, which is a manifestation of heart failure.

      AF can sometimes be part of a syndrome called tachy-brady syndrome which results in sudden termination of AF with a prolonged duration of lack of heart beat and thus collapse/ lose consciousness (Syncope)

      Due to the rapid rates and altered metabolic state of the myocardium, rapid development of heart failure could result and this is referred to as tachycardiomyopathy which is usually reversible.

      How do we medically manage this arrhythmia?

      » Stroke prevention

      The main goal of prevention or treatment of AF is STROKE prevention.

      So every patient with AF should be on blood thinners of any form unless contra-indicated. Blood thinners act by various mechanisms and depending on the type used, regular monitoring of their efficacy need to be checked for some, while some others need no monitoring.

      Basic type is aspirin which is used in low risk patients. For at risk patients Acitrom/ warfarin are commonly used drugs but their level need to be monitored to avoid under or over anti-coagulation which could lead to either unwanted clot formation in the heart or bleeding elsewhere including the brain.

      Third variety is a group of newer drugs which are more specific and predictable in their mechanism and duration of action. Thus no monitoring is necessary.

      » Symptom control

      Drugs to control the heart rate are uniformly prescribed to majority of the patients- they are called beta-blockers or calcium channel blockers or Digoxin.

      Sometimes efforts are made to get back the normal rhythm by using special drugs which are called anti-arrhythmics(AADs). These are associated with risks in some patients as they cause more dangerous arrhythmias in some unless they are started carefully and their effects monitored on ECG regularly. Further, patients with underlying heart, liver or kidney disease limit their usage and we have to look at more invasive options to help maintain normal rhythm.

      What are the interventional means by which we can manage AF?

      For patients with AF, both quality of life, risks and longevity improve if they are brought back to sinus rhythm. Many a time AADs are effective in terminating the tachycardia/ AF and maintaining sinus rhythm which is the goal. However, those who have contra-indication for such drugs, those with severe symptoms despite drugs, those whose heart rates are not controlled with drugs and have developed complications are candidates for invasive

      Radiofrequency Ablation (RFA) - This is a breakthrough procedure for patients suffering from AF. People who have short duration of AF and have intermittent AF are best candidates suited for this complex procedure. We utilize advanced technologies like 3D mapping to create the geometry of the atria and then locate the areas of abnormal conduction and burn and destroy the abnormal tissue in the left atrium. At the junction of the left atrium and the pulmonary veins (vessels bringing in pure blood to the heart from the lungs) there will be muscle bundles running across which act as triggers to start such episodes of AF in the majority of patients with paroxysmal AF. By burning them we take-off the triggers and render AF non-inducible. Sometimes these triggers could be on the right side and we map the right atrium and burn/ ablate the abnormal focus.

      In patients with severe valve disease, kidney failure on hemodialysis, chronic obstructive airway disease, severe pulmonary hypertension etc, and the success rates of RF ablation is not satisfactory and generally are managed non-invasively.

      Cryoballoon ablation - this modality is available in most advanced countries and has specific situations where it performs as well as RFA. It utilizes freezing balloons inserted inside the heart to freeze and destroy the muscle sleeves across the pulmonary veins. Advantages include shorter procedures and lesser risks.

      What is the success rate of RFA in maintaining sinus rhythm?

      Many factors determine the efficacy of ablation. Chances of maintaining sinus rhythm over a longer period of time after RFA is determined by

      » the duration of AF prior to ablation: more recent onset AF have better success than long standing AF.

      » whether AF is paroxysmal (intermittent) or persistent (continuous): paroxysmal AF have better outcomes to persistent ones.

      » the presence of underlying structural heart disease like a weak heart (LV dysfunction), thick ventricles (hypertrophy), abnormal valves (valvular heart disease), dilated chambers (either the LV or the LA): success rates are lower if there are significant underlying abnormalities.

      » Co-existing disorders like Obesity, snoring, COPD, alcoholism etc.

      » Age at ablation: more degenerative changes in the atrium leads to lower success rates and higher complications related to anaesthesia.

      Lastly, operator factors play a prominent role in the success.

      The success rate of RFA for AF is in the order of 60- 90% depending on various factors mentioned above. Factoring in those issues, the results are very rewarding in paroxysmal atrial fibrillation. Whereas in persistent or long standing atrial fibrillation, the success rates are modest with one procedure, whereas with 2 or more procedures, & with other factors like hypertension, heart failure, obesity and obstructive sleep apnea being controlled, the results are promising.

      What are the risks associated with AF ablation?

      AF ablation is one of the most complex procedures performed. Depending on the duration of the arrhythmia, the procedure lasts longer and demands more extensive ablation. Overall risk is ~5% including both minor and major complications. Risk to life is real but rare.

      The risks involved could be

      » related to the access route: groin hematoma due to local bleeding, inadvertent puncture of the artery with further pseudo-aneurysm or fistula formation;

      » related to the anticoagulation: excess could cause hemorrhage and inadequate could lead to a stroke; To avoid a stroke during ablation, we use intravenous heparin and monitor its levels periodically.

      » related to the left atrial access or ablation itself which could cause perforation of the atrium leading on to dangerous complication called cardiac tamponade (collection of blood around the heart and drop in blood pressure) sometimes requiring emergency open heart surgery and could be very rarely fatal.

      » Very rare complications include pulmonary vein stenosis or esophageal injury or phrenic nerve injury or conduction block. This group of complications has come down drastically after the advent of more sophisticated technologies.

      » related to the anaesthesia, especially if general anaesthesia is preferred.

      Are there any other alternatives in AF?

      Yes. If a patient is not a candidate for long term blood thinners for stroke prevention, we can consider device closure of the left atrial appendage. This can be done using an umbrella like device which stays permanently in the heart of the patient. These devices seal the entrance of a vestigial part of the atria called the appendage. Most of the clots are formed here and by this device we prevent strokes. However the procedure though complex and involves risks, it has scope in a small subgroup of patients in whom anti-coagulation to prevent stroke cannot be used or patient risk of AF ablation is high.

      There are various devices in the market to achieve closure of the left atrial appendage, some of which are still experimental.

      Surgical closure of the LAA also is an option but more invasive.

      Always, when we feel the risks outweigh the benefit, we go with non-invasive therapy!

  • Lead Extractions
    • What is device infection?

      A pacemaker is a foreign body inserted under the skin or muscle. Sometimes the pocket in which it is placed, or the leads which enter the vein and into the heart, could get infected. Commonest cause for infection is bacteria getting into the pocket during implantation. Other cause could be bloodstream spread from inter-current infections like pneumonia, urinary tract infection, iv line site infection etc.

      How is it diagnosed?

      Most often device infection occurs late after implantation. rarely severe infections can present within weeks of implantation.

      Device infection could present with swelling of the pocket, pain, redness and itching at the site, rarely frank pus oozing out and sometimes the device protruding out of the site. Fever need not be present.

      What is the treatment?

      Once a patient is diagnosed to have device infection, antibiotics should be initiated at the earliest after taking blood and pus for microscopic examination and culture to recognise the organism causing infection.

      After initial antibiotic therapy, the entire device and the leads should be pulled out (lead extraction). If there is blood infection, antibiotics would be given for a longer period

      What is lead extraction?

      The procedure of bringing out the pacemaker leads is called lead extraction. This could be a simple procedure if the leads are not implanted for a short duration. More often extraction happens years after implantation complicating the procedure. Lead extraction is one of the most difficult procedures if defibrillator leads or multiple leads have to extracted and physicians trained in this procedure are few.

      When is lead extraction indicated?

      Device infection is the commonest cause for lead extraction.

      Pacemaker infection incidence is growing rapidly around the world disproportionate to the rate of implantations. Sterile precautions during implantations tend to prevent almost 95% of the infections. But any intercurrent infection can lead to seeding of bacteria in the pacemaker pocket and further formation or pus, The device infection can also involve the pacemaker leads. Survival of a patient is much better if the entire system (PM + Leads) is removed rather than removing only the pacemaker.

      Other indications are

      » presence of too many leads- can cause venous occlusion.

      » lack of space/ veins for new leads to be implanted due to extensive fribrosis.

      » abandoned leads which cause problems like life threatening arrhythmias- especially the ICD leads.

      » defective leads recalled by the industry

      What are the complications of lead extraction?

      Lead extraction must be performed by only trained operators as it could be very dangerous in inexperienced hands. The leads can be pulled out both from the pacemaker pocket site and in some situations from the thigh route.

      The longer the lead stays in the body the harder is the procedure. We need special equipment to free the lead from the blood vessels and the heart to which it could be stuck at various points.

      Major complications which could be sometimes pose serious risk to life include

      » tearing of the large veins

      » laceration of the heart –a part of the heart muscle coming out with the lead tip

      » cardiac perforation- blood collects outside the heart and sudden drop in BP

      Due to the newer technologies both in terms of the lead characteristics and equipment for extraction, the complication rates are under 3% making this procedure relatively safe in trained hands.

  • Pace Maker
    • What is a pacemaker (PM)?

      Our heart is made of muscle to pump blood to the whole body.

      For the heart to pump, it needs electrical stimulus which has to travel from the point of production i.e, the SA node (the generator of the heart) and travel down to the AV node (the transformer) and then Bundle branches (the wires) to reach the muscle. This is the electrical system of the heart akin to that in our house!

      This keeps our heart rate at 50- 100 beats per minute. A defect in any part of the electrical system, gives rise to decreased heart rate and sometimes even no heart rate.

      In scenarios where the heart rate is slow referred to as Bradycardia, pacemakers are implanted if they cause symptoms of low cardiac output like fatigue, breathlessness/ dyspnea, giddiness, loss of consciousness, chest pain etc. All treatable causes of bradycardia are ruled out before deciding on a pacemaker implantation.

      A pacemaker is a small metal box made of alloy housing the battery, circuits and the software, which in all does not exceed the size of an average match box!

      When the heart rate is below the rate set the pacemaker delivers tiny current to stimulate the heart but in case the patient’s own heart rate is above the minimum set limit, it watches silently always prepared to back up in case the rate falls.

      Where is the pacemaker implanted?

      The usual site of pacemaker implantation is the side opposite the dominant hand. That accounts to a majority being on the left side. The site of placement of the pacemaker is about 2-3cm below the collar bone or the clavicle. An incision of about 4-5 cm is made and the leads (pacing wires) are inserted into the vein and fixed to the right ventricle and right atrium.

      What are the types pacemakers?

      There are different types of pacemakers with each being used in a specific clinical scenario.

      The simplest of them is the single chamber pacemaker which has limited indications in this era.

      The most commonly preferred pacemaker is the dual chamber pacemaker. This system has 2 pacing leads one each in the atrium and the ventricle. This is indicated in patients who do not have chaotic atrial activity called atrial fibrillation. It is preferred over the single chamber system as it offers various advantages most importantly atrio- ventricular synchrony which amounts to a better cardiac output. There are other algorithms which make the system more sophisticated and better.

      For bradycardia, one of the above 2 types of devices are used. However, in patients with heart failure and severe left ventricular dysfunction, an advanced pacing system or heart failure device called the Cardiac Resynchronisation Therapy (CRT) is preferred in select patients.

      What are the indications for pacemaker implantation?

      Patients who have a low heart rate below the normal for age and are symptomatic due to that are candidates for a pacemaker. This also includes children who could have heart block even by birth. Sometimes, a patient has a condition which demands certain drugs but the heart rate is low preventing usage of such drugs can also be implanted with a pacemaker and the drugs continued.

      Bradycardia alone is not an indication as it could be seen in many athletes and sportspersons which is an evidence of high vagal tone and of health rather than disease!

      What are the causes for bradycardia?

      Causes of bradycardia could be reversible or irreversible.

      Reversible causes include drugs as the most common culprits, then medical conditions like hypothyroidism, head injury, myocarditis etc The irreversible causes are usually degenerative – advanced age, and could also be rarely due to complications of surgical procedures and ablations for arryhthmias.

      What are the recent developments in this technology?

      The figure depicts how the science has advanced (depictive of only of one company products).

      From a simple single chamber pacemaker, there have been significant reductions in size; improved battery longevity; rate response algorithm to give you better heart rates with exercise instead of a fixed rate irrespective of the level of activity; dual and even triple chamber pacing systems for heart failure; MRI compatible pacemakers; and now even pacemakers as small as a cigarette butt.

      The latest in the offering is the leadless pacemaker called the Nanostim which is a single chamber pacemaker without any leads and this is placed in the heart through the thigh vein. At the present time, it has limited indications.

      What precautions need to be taken in patients with PM?

      Special precautions are to be followed at various phases to avoid unnecessary problems.

      During the immediate post implantation phase, it is advised to avoid heavy work especially with the arm on the side of implant. That includes lifting weights, swinging arms to extremes etc.

      The wound site is to be taken care of so as not to allow contamination thus preventing infections which is highest in this period.

      Driving can be resumed after a month for most pacemakers unless physician advises u not to do so under certain circumstances.

      If u do not have an MRI compatible pacemaker, please remember to inform the doctors before radiology scans so they avoid magnetic fields which could cause device malfunction.

      If you have to pass through the security checks at airports etc, keep your PM ID card ready to show them and avoid excessive magnetic field exposure.

      Some electronic ware could interfere with the device functioning. In general it is safe to work with any equipment at a distance of a foot.

      Use of instruments which emit/ receive electromagnetic rays including mobile phones need to kept away from the side of implant.

      After a few weeks one can resume normal activities.

      What are the risks involved?

      With implantation of regular pacemakers, the risks are negligible in the implantation stage. However, there are occasional incidents of cardiac perforations and damage to the vein/ inadvertent arterial tear and bleeding into the thorax needing further interventions and even risk to life.

      Infection of the device pocket is the only major concern for both the physician and the patients as this mandates removal of the device and a protracted coarse in some situations and could also be life threatening.

      Chest X-Ray of a young boy with a dual chamber pacemaker- 2 wires in the heart!:

  • Radio Frequency Ablation
    • What is RFA?

      RFA means radiofrequency ablation. Ablation means to burn. And it is called RFA because it uses radiofrequency energy to produce heat needed to burn the tissues in the heart.

      Are there any other sources of energy?

      There are various types of energy to destroy pathologic tissues in the heart. They include extreme freezing- cryoablation; use of laser and also use of ultrasound have been tried.

      By far the most common energy source is RF as the results are long lasting adn recurrences of arrhythmias are less compared to cryoablation.

      How do we deliver RF energy to the heart?

      We use special catheters (insulated wires with platinum or gold tip) for this purpose. The catheters are on one end connected to the RF generator and the other end is in contact with the tissue to be ablated.

      How long does RFA take to cure arrhythmias?

      The time duration of ablation depends on the type of arrhythmia, ranging from a couple of minutes for simple superficial lesion formation to almost an hour in complex ablations.

      What are the complications of RFA?

      We must realise the purpose of RFA is to destroy the underlying tissue by delivering significant amount of heat. Thus it could be dangerous if we are ablating closer to critical areas of the heart.

      Ablation near to the critical areas of the conduction system can cause conduction defects, even requiring pacemakers at times.

      Likewise certain areas of the heart are thinner than the rest leading to perforation of the chamber causing significant morbidity and sometimes mortality.

      Very rarely, due to the charring of blood cells, there could even be brain strokes.

      The complications are less with careful use of the techniques, technological advances in catheters and ultimately experience matters.

      Overall the risk with RFA in simple cases are < 1% and with complex cases is about 2%.

  • Sudden Cardiac Death
    • What is Sudden Cardiac Death or SCD?

      Sudden cardiac death is a natural death due to cardiac causes, heralded by abrupt loss of consciousness within one hour of the onset of acute symptoms.

      The patient may or may not have a pre-existing heart disease, but the time and mode of death are unexpected.

      Incidence of SCD is about-15% of overall deaths and increases with age.

      What are the causes of SCD?

      Most common cause SCD is coronary artery disease (Heart Attacks) Other relatively common causes are- genetic diseases like cardiomyopathies and ion channel defects. Eg- Brugada Syndrome, Long QT syndrome, ERPS etc

      How do we identify patients who are at risk of SCD?

      First and foremost is to investigate with detailed history and tests- both invasive and non-invasive. This will help us identify the underlying cause.

      » Echocardiogram (ECHO) to look for Left Ventricular Dysfunction which is a major risk marker of SCD

      » Holter to look for very slow or rapid heart rates and evaluate the cause of syncope.

      » Angiogram to rule out coronary artery disease which is the commonest cause of SCD

      » MRI to rule out structural abnormalities like cardiomyopathies etc

      » Genetic studies to rule out carrier state of certain high risk mutations in families with a known disease

      How do we treat patients at risk of SCD?

      Treat the underlying cause.

      Drugs which are shown to reduce the risk of SCD, like betablockers, Anti-arrhythmic drugs, cholesterol lowering drugs called statins etc

      Implantable defibrillators (ICDs) are complex devices which are of benefit in both primary and secondary prevention of SCD.

      There are some specialised invasive procedures like sympathectomy for some inherited arrhythmia syndromes, Aneurysmectomy for badly damaged heart.

      Radiofrequency ablation is another modality by which we can modify the risk of SCD in patients with post heart attack scars in the heart. In this form of therapy, we use sophisticated equipment to localise the area of the scar and the circuit of the arrhythmia and burn at critical areas to get rid of the circuit and thus prevent recurrence of the arrhythmia like ventricular tachycardia and fibrillation.

      How do we manage patients who have survived SCD?

      After the underlying treatable causes are ruled out or corrected, the patient needs to be followed up and reassessed to study the need for ICD implantation to prevent further risks.

      What is an ICD and how does it work?

      It is a specialised form of pacemaker that monitors the heart beats and recognises dangerous rhythms like VT and VF and delivers shock form inside to bring back the patient to sinus rhythm. The energy delivered is very small compared to that delivered for external defibrillation. The ICD has specialised algorithms which detect and differentiate a SVT from VT based on the onset, intervals of EGMs, stability, morphology of the EGM and relationship between the atrial and ventricular signals. Once diagnosed as VT a shock upto 40 Joules is delivered and it re-assesses the rhythm.

      How effective are the ICDs in preventing death?

      Randomised trials support the use of ICDs for secondary prevention of sudden cardiac arrest regardless of the type of underlying structural heart disease where it has shown clinically and statistically significant reductions in sudden death and total mortality compared with antiarrhythmic drug therapy The magnitude of risk reduction is in the order of 50% for arrhythmic death, and 25% for all-cause mortality.

      What precautions should be taken by the patient with ICD?

      The patient should consult the doctor ideally after every shock in the initial period so that inappropriate shocks are ruled out and if present, the ICD could be programmed further to avoid inappropriate shocks.

      Patient should avoid magnetic fields and if inadvertently had gone too close to a strong magnetic field, he may consult us for a device check.

      If there is any surgery planned, the surgeons have to be informed and the concerned electrophysiologist to be contacted to switch off the shock therapy to avoid inappropriate shocks while using cautery during surgery.

      Driving after ICD implantation is a tricky issue. If not shock delivered, a patient can drive after the initial month after consulting the treating physician. However, if one receives a shock, it is a matter of danger to self and co-commuters and a physician opinion is mandated.

      What are the advances in SCD management?

      » Recent scanning techniques have helped identify even minute structural abnormalities. MRI is an important tool in this regards.

      » Genetic testing is a valuable tool especially with regards to genetic counselling.

      » ICDs which are MRI compatible and longer battery life are also major advances in this regard.

      » Subcutaneous ICDs especially useful in a subgroup of patients is another landmark.

      » Research into the mechanism of ventricular arrhythmias have opened up the scope of RF ablation in this field!

  • SVT
    • The electrical system of the heart!

      What is life without a spark! All of us yearn for those little sparks & electrifying experiences in life! Let’s look at the heart.

      The heart is nothing more than your fist’s size but is expected to work without a break! The average heartbeat of a normal human being is about 70beats/minute. Can u imagine your heart has to beat on an average 100- 120 thousand times a day for your lifespan! It needs energy to sustain which comes from the blood pumped by the heart itself. In this regard, the “Heart is its own Servant”

      Don’t you want to think what makes the heart tick?

      Akin to the Brain and its neural circuits- the spinal cord and the nerves, our heart also has a neural circuit of its own. The perennial generation of impulse or small electric current by the sino-atrial node which is the generator of the heart and an intact conduction system further down, causes the heart to beat all at once with each impulse flowing down.

      So what is an arrhythmia?

      You are watching the republic day parade appreciating the awesome march by various contingents of the armed forces. Now, imagine the army parade with one odd man getting the foot wrong!! The march is no more the same as the rhythm is lost and the contingent falls apart!

      Now such an event can happen in the heart when one abnormal beat can appear unrelated to the dominant pacemaker of the heart – the sino- atrial node. The rhythm is lost as we have an extra beat which can sometimes be multiple or can trigger a series of abnormal beats. This triggering beat or impulse is like odd man who kills the rhythm. Anything apart from the established normals for the rate or regularity of the heart beat is referred to as ARRHYTHMIA.

      If a tremor in the brain is linked to seizure, a tremor in the heart- could mean the last moments of our existence! The electrical system of the heart with its critical components, continually & optimally function to let us enjoy a seamless journey called LIFE.

      With just this information above,

      Aren’t you grateful for that electrifying experience every moment of your life, which keeps you well and alive? Our heart is like a worker often neglected but sorely missed when absent. Whereas the intermittent sparks in life are treasured, you would rather not have such sparks in your heart! Now, don’t you agree if I say- Heart is just a lump of muscle but for the electrical system provided by almighty!

      To set this right, we the ELECTRICIANS of the heart are at your service…

      What is SVT?

      The heart has 4 chambers. 2 upper chambers called the atria and 2 lower chambers called the ventricles. The upper chambers receive the blood into the heart and the lower chambers pump blood out of the heart. Any arrhythmia that is confined to the regions above the ventricles is called SVT or supra ventricular arrhythmias. Tachycardia means rapid heartbeats, and is recognized when the heart rate is above the upper limit of normal- 100beats/ minute.

      What are the types of SVTs?

      There are different types of SVTs depending on the mechanism responsible for the rapid heart rate. Common varieties are AVNRT, AVRT/ WPW syndrome and AT in that order.

      How do we diagnose them on ECG?

      Often the ECG during an episode of palpitations reveals the mechanism of tachycardia. The response to drugs also provides clues to narrowing the diagnosis. However, in a significant proportion, further invasive test called EPS (electrophysiological study) is needed to diagnose and localize the site of abnormality for further treatment.

      How do we treat SVTs in the emergency room?

      When a patient presents with SVT, we inject certain drugs which terminate the tachycardia instantly. For this there are different types of drugs each with a different success rate and side effects. The decision as to which drug to be used is taken by the emergency physician after taking a brief history and examination. Sometimes the SVT terminate to physical maneuvers which increase the vagal tone.

      What is EPS?

      EPS stands for electro=physiological study. We perform this study when the mechanism is not clear; when the tachycardia is not documented but patient complains of palpitations or prior to performing RFA.

      For the purpose of the study, different types of catheters are used and placed at critical locations in the heart under X-ray guidance. Tiny electrical impulses are given at these locations and the tachycardia is induced and studied further. The abnormal circuits are localized for ablation.

      What is RFA?

      RFA means radiofrequency ablation. Ablation means to burn. And it is called RFA because it uses radiofrequency energy to produce heat needed to burn the tissues in the heart.

      What are the success rates of RFA in SVT?

      Success rates vary from 90% for some types of tachycardia to 98% or more for some others. Overall, the commoner types of SVTs have higher success rates.

  • Ventricular Tachycardia
    • The electrical system of the heart!

      What is ventricular tachycardia (VT)?

      Ventricular Tachycardia is an arrhythmia where the lower chambers of the heart called the ventricles suddenly overtake the normal heart beats. This fast heart rate usually in the order of 160- 200 beats result in abnormal propagation of current in the ventricular muscle thereby causing lower cardiac output and its sequelae.

      How does VT occur?

      There are many mechanisms how VT can occur- focal, triggered or re-entrant.

      It could occur from a few cells when it is called focal origin and then the current spreads to the rest of the ventricle. There are more common in the younger age groups and are amenable to curative procedures as they often arise from predictable locations.

      Next, it could be due to drugs or other underlying conditions which could trigger abnormal ion fluxes and result in Ventricular tachycardia or fibrillation.

      Another very common type of VT occurs when the current revolves around an area of dead tissue or within a well-defined circuit. This is called re-entrant VT as the current goes round and round in the same path. This type of VT is again very amenable to cure with the latest technologies.

      What are the symptoms of this dangerous arrhythmia?

      Though VT can be dangerous, sometimes it provides time for the patient to reach or be brought to the hospital with symptoms.

      Patients can only complain of palpitations as they experience rapid heart beats or they could present with manifestations of decreased cardiac output. This includes breathlessness and giddiness and frank loss of consciousness.

      Sometiems, VT degeneartes into more dangerous and fatal arrhythmia called ventricular fibrillation.

      VT is poorly toletated in people who have had heart attacks earlier and have residual poor ventricular function. It is often the terminal event in patients suffering from serious structural heart disease and also a major cause for sudden cardiac death.

      What are the causes of VT?

      The cause of VT is generally related to the underlying heart disease.

      Most often coronary artery disease (CAD) and past heart attacks are the culprits. However, patients with heart failure are at high risk of developing VT even if they don’t have CAD.

      In the younger age groups, idiopathic VTs are more common, meaning a clear identifiable cause is not obvious.

      In patients with genetic defects with or without recognizable structural heart disease, sudden cardiac arrest is again common and they need special care with regards to assessing their risks of sudden cardiac arrest, screening their families to identify high risk subjects, genetic counselling etc

      What are the treatment options available?

      Treatment options available are

      » Medical (drugs)/

      » RFA (burning the substrate),

      » Surgery (especially if associated with gross dilatation and aneurysm of the left ventricle)

      » ICD (effective rather non-curative therapy).

      What drugs are available and what care have to be taken while using them?

      VT can be treated with a wide range of drugs depending on the mechanism.

      In general drugs used to treat arrhythmias are called anti-arrhythmic drugs.

      They are classified based on the mechanism of action and the type of receptors they act on. Thus some ventricular arrhythmias which are automatic are amenable to control by beta-blockers, some others are controlled by calcium channel blockers, while some like post heart attack/ scar related VTs need more potent but toxic drugs which act on the sodium and potassium channels.

      What are the invasive options to cure VT?

      There are 2 invasive options available- first is radio-frequency ablation (RFA) and the other is surgical management.

      If it is decided to perform RFA, we first perform 3D mapping of the chamber concerned and create a geometry and then try and locate the site of origin of the VT or the circuit responsible for the same. Then ablation is performed and the focus eliminated.

      Surgical management of VT is an option especially when the left ventricle has large scars with severe dilatation and dysfuntion &/or is aneurysmal.

      Are there implantable devices to treat VT?

      Yes. They are called the ICDs. ICD is a special kind of a pacemaker which is capable of detecting the onset of any arrhythmia and appropriately treating the ventricular arrhythmias with high accuracy. It is in short called the SHOCK BOX.

      However, most of the times the ICD tries to stop the tachycardia without a shock by means of ATP (Anti Tachycardia Pacing) which is also effective in a significant proportion of patients. This helps in prolonging the battery life, reducing the damage to the heart and also avoids the psychological impact a shock can have on some patients.

      What are the recent advances in devices used for management of VT?

      More recently, there are studies to show that primary RFA for a VT is reasonably good in preventing recurrences and can be used in adjunct to an ICD or in lieu of one when cost is a factor.

      The ICDs are getting smaller and have better battery longevity. Features to reduce inappropriate shocks and further, MRI compatibility of recent devices make them the first choice to treat ventricular arrhythmia after reversible causes are treated.

      A broad and bizzare VT (Top image) compared to the baseline ECG (bottom image)?

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