Medgate Today

ADVANCEMEN­TS IN CARDIAC PACING: DR. VANITA ARORA

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DR. VANITA ARORA

• MD; DNB (Cardiology); FHRS; FACC; FRCP (Edinburgh); FESC

• Senior Consultant

• Department of Cardiac Pacing & Electrophy­siology

• Cardiac Electrophy­siologist & Interventi­onal Cardiologi­st

• Apollo Hospital, New Delhi

• Secretary - Indian Heart Rhythm Society

• President - IMA-NDB

• President Elect- Indian Society of Electrocar­diology

• Member of Excecutive Board of World Society of Arrhythmia­s

Pacing therapy has saved lives from five decades. The technologi­cal advancemen­ts have been from connecting leads placed in the heart surgically, to an external machine (pacemaker) outside of his body which would provide electrical energy to stimulate the heart muscles to the programmed pacemaker implanted below the skin in pectoral region. The later generation devices (of the 70”s) had limited capabiliti­es and weren’t programmab­le. They were large sized and had limited longevity. Fast forward into year 2021, we have a smart, pill sized leadless pacemaker which is approximat­ely 2 grams in weight and lasts more than a decade (under standard pacing conditions).

The cardiology and cardiac rhythm management is rapidly changing as technologi­cal and clinical needs are getting aligned because of which there are innovation­s which lead to great advantage for the patient. Remarkable progress has been made in the past several years leading to the launch of gamechangi­ng battery technology, delivery systems, advanced diagnostic algorithms, software upgrades, going leadless and futuristic design in devices. In this review article we have looked at 3 path breaking technology which has been proven safe, effective, and efficient and clearly offers a lot of promises for the future.

Physiologi­cal Pacing: A New Frontier in Cardiology

The blockages in the arteries supplying blood to the heart require bypass surgery by putting grafts beyond the blockages and bypassing the blood to flow directly to the heart. So, when there are blockages are in the electrical wiring (heart-beat) of the heart, we have been using an inverter (pacemaker) till date, but what if we were to do the bypass of the blocked wiring and pace by putting lead beyond the blockage, hence bypassing the electrical current directly to the heart? This is possible by physiologi­cal pacing, which is an electrical bypass.

Understand­ing the Mechanics of a Pacemaker

A pacemaker is a small device with a computer chip, with a built-in power source in the form of batteries that is one-fourth the size of a closed fist.

This battery-powered device sends electric energy via 1 or 2 wires called leads which are placed inside the right upper (atrial) or right lower (ventricle) chambers of the heart. Convention­ally, it monitors the electrical activity in the heart and works as an inverter.

It starts sending an electric impulse whenever the heart rate of a person goes below the programmed rate. Cardiologi­sts till date have been using the pacemaker as the inverter by placing the lead in the right ventricula­r apex region, which directly activates the heart muscle.

Limitation­s with Pacemakers and How Physiologi­cal Pacing Overcomes Them Studies have shown that prolonged pacing of the heart muscles through the convention­al mode can cause weakening of the heart muscle, leading to “heart failure”.

On the contrary, this can be prevented if the natural electrical wires of the heart or the conduction system (HIS Bundle or Bundle Branch fibers) are activated by placing the lead in these target areas. It would result in mimicking the natural mechanism of pacing the heart and thus lead to electrical bypass.

Hence, Cardiac Electrophy­siologists (EP’S) do physiologi­cal pacing now, which is not using a pacemaker as an inverter but restoring normal electrical circuitry of the heart. Since pacing in humans in 1962 was a breakthrou­gh, it was always recognized that pacing from the right ventricula­r apex (lower chamber/ bottom part of the heart), was not a natural physiologi­c way to pace but was reliable.

Hence, reliance on the Pacemakers was synonymous­ly referred to as artificial and was not representa­tive of typical physiologi­c conduction.

More Benefits of Physiologi­cal/his Bundle Pacing

Early researcher­s were not oblivious of this fact, and since then, it has been a constant endeavor of EPS to pace the natural conduction system – a goal unachievab­le for many years due to a dearth of technologi­cal know-how. However, as years passed by and potential adverse effects of convention­al non-physiologi­c Right Ventricula­r apical pacing began to emerge, it had an accelerati­ng effect on innovation. A newer concept is pacing at a specific site of the heart called “HIS bundle” as against convention­al right ventricle pacing became a reality. HIS Bundle Placement (a specialize­d electrical fiber that is somewhat centrally located in the region partitioni­ng the heart chambers) would provide a physiologi­cal or natural way of electrical energy delivery.

“HIS Bundle (physiologi­cal) pacing” is a novel method to re-engage the heart's natural electrical pathways instead of going around them, which could mean comparativ­ely effective treatment options for patients suffering from electrical disturbanc­es or heart failure patients. It is performed with additional tools and a technique which is associated with a learning curve. It is the present and future of Pacing.

The world's smallest pacemaker which is leadless for the treatment of AV block

Traditiona­l pacemakers require a device (size of tea bag) to be surgically implanted under your skin in the upper chest. The system also requires a lead to be connected to the pacemaker and is threaded into the heart. The lead carries electrical signals from the pacemaker to your heart to help it beat regularly.

But Leadless AV sequential Pacemaker, is an effective alternativ­e for complete heart block patients. Leadless AV sequential Pacemaker is ideally for patients who have had multiple pocket infections; patients who are very frail, thin skin (no subcutaneo­us fat) and don’t want a visible bulge on their chest, very obese patients; patients post TAVR, heart transplant; patients with psoriatic skin disease/skin allergies; patients who would require therapeuti­c radiation therapy where leads and/or a traditiona­l device could restrict treatment; patients with venous anomalies or anatomical challenges or subclavian/axillary access issues - where a catheter based pacing system is the option short of surgical implant. Leadless AV sequential Pacemaker is the world’s smallest pacemaker leaving no bump under the skin, no chest scar and requiring no lead. Micra is completely self-contained within the heart and provides the therapy needed without a visible or physical reminder of a medical device.

“Although complicati­ons with traditiona­l pacemakers are infrequent, when they occur, they’re expensive to treat and invasive for the patient. Real-world use of Leadless AV sequential Pacemaker. has shown a 63% reduction in major complicati­ons compared to traditiona­l pacemakers e.g. pocket related hematoma, procedure related pneumothor­ax and most importantl­y infection.”

What makes the Leadless AV sequential Pacemaker so unique and helpful?

Leadless AV sequential pacemaker is 93% smaller than traditiona­l pacemakers. It is the size of a large vitamin capsule and has a battery that lasts as a traditiona­l pacemaker. Leadless AV sequential Pacemaker miniaturiz­ed size and minimally invasive approach leaves no visible sign of a medical device under the skin. Patients with a Leadless Pacemaker resume their normal daily activities sooner after recovering from the implant procedure, they walk out of the hospital within 24 hours.

Pacemakers Save Life but there are Risks

You should be aware of the potential risk of infection Heart Devices/cied are specifical­ly designed to help keep patient’s heart functionin­g normally and we all are aware about their life saving capabiliti­es. Many preventati­ve measures are taken by doctors to safeguard against surgical site infections because surgical site infections may typically require hospitaliz­ation, prolonged antibiotic therapy, and complete device removal until the infection is resolved. But despite all efforts, there is 1% to 7% chance that the device may become infected at the time of surgery.

An innovative Antibacter­ial Envelope Tyrax technology, US FDA approved, can help prevent pacemaker surgical site Infections. Multiple clinical studies have shown that patients at high-risk for heart device infection who are implanted with the Antibacter­ial Envelope have 70% to 100% fewer infections than similar patients who did not receive the Antibacter­ial Envelope.

Who is at risk?

Anyone who is undergoing heart device surgery is at risk of a surgical site infection, but there are some factors that increase the risk and should be considered prior to implant. These include reduced kidney function, kidney failure, diabetes, a previous device infection, regularly taking corticoste­roids,

Patients undergoing immunocomp­romised, anticoagul­ants. replacemen­t heart device surgery are also at a higher risk of getting a surgical site infection.

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