Can the Heart’s Electrical System Be Repaired?

The heart’s electrical system can be repaired, though the meaning of “repaired” depends on the problem and the tools involved. For decades, the main fix has been hardware: electronic pacemakers and defibrillators that substitute for faulty wiring rather than restore it. That is changing. Researchers are now building biological pacemakers from gene therapy, engineering conductive patches that bridge dead scar tissue, editing inherited mutations with CRISPR, and even using pulses of light to override dangerous rhythms. Most of these approaches remain in animal studies or early human-cell experiments, but the trajectory is clear and the progress over the past ten years has been striking.

A Quick Look at What Can Break

The heart’s electrical system is a chain of specialized tissues that generate impulses and route them through the muscle in a precise sequence. The sinoatrial node fires first, setting the pace. That signal spreads through the atria, pauses briefly at the atrioventricular node, and then races down the His bundle and its branches into the ventricles. Each link in this chain has a distinct cellular makeup, with different protein channels, different electrical properties, and different vulnerabilities.

1PubMed. The cardiac conduction system: A narrative review

Problems can arise at any point. The sinoatrial node can slow down or fail entirely, a condition sometimes called sick sinus syndrome. The atrioventricular node can develop block, severing communication between the upper and lower chambers. Scar tissue from a heart attack can interrupt normal signal flow through the ventricular walls, creating the conditions for dangerous re-entrant arrhythmias. And some people are born with mutations in the ion channels that shape the electrical signal itself, predisposing them to conditions like long QT syndrome or Brugada syndrome.

2PubMed Central. Deciphering Common Long QT Syndrome Using CRISPR/Cas9 in Human-Induced Pluripotent Stem Cell-Derived Cardiomyocytes

Why Electronic Pacemakers Are Not the Final Answer

Electronic pacemakers have saved millions of lives since their invention, and modern devices are remarkably reliable. But they come with a well-known set of trade-offs. Conventional transvenous pacemakers run wires through veins into the heart, and those leads can fracture, dislodge, or become a nidus for infection. The devices themselves need periodic battery replacement, which means repeat surgery every several years.

3PubMed. Leadless Cardiac Pacemakers: Back to the Future

A subtler problem is that traditional pacemakers often stimulate the heart from the wrong spot. Pacing the right ventricle, the most common approach for decades, activates the ventricles in an abnormal sequence that can gradually weaken the heart muscle over time. Newer techniques aim to fix this by pacing the heart’s own conduction fibers directly.

Pacing the Heart’s Own Wiring

His bundle pacing and left bundle branch pacing represent a shift in philosophy. Instead of bypassing the conduction system entirely, these methods deliver the pacing impulse directly into the surviving fast-conducting fibers. The result is a more natural activation pattern. A systematic review and meta-analysis found that physiological pacing through these approaches produced shorter QRS durations and better cardiac function compared with conventional right ventricular pacing.

4PubMed. Safety and efficacy of His-bundle pacing/left bundle branch area pacing versus right ventricular pacing: a systematic review and meta-analysis

In heart failure patients specifically, both His bundle pacing and left bundle branch pacing have shown improvements in cardiac function and clinical outcomes. His bundle pacing restores more physiological conduction with better synchronization, while left bundle branch pacing enhances left ventricular activation and overall cardiac performance.

5PubMed Central. His Bundle Pacing and Left Bundle Branch Pacing in Patients with Heart Failure

These techniques are already in clinical use and spreading quickly, but they still rely on electronic hardware. They are a smarter version of the same basic idea: an implanted device delivering electrical current. The next frontier aims to eliminate the device altogether.

Creating a Biological Pacemaker

The most ambitious approach to repairing the heart’s electrical system is to build a new pacemaker out of living tissue. The idea is to convert ordinary heart muscle cells into pacemaker cells by delivering a single gene, TBX18, which plays a key role in the development of the sinoatrial node during embryonic life. When researchers injected an adenoviral vector carrying TBX18 into pigs with complete heart block, biological pacemaker activity appeared within two days and persisted for the full 14-day study. The animals showed enhanced autonomic responses and better support of physical activity compared with controls.

6PubMed Central. Biological pacemaker created by minimally invasive somatic reprogramming in pigs with complete heart block

A key concern with adenoviral delivery is that it is inherently temporary; the virus does not integrate into the cell’s DNA, so the effect fades as the cell divides or the viral payload degrades. That is why a follow-up study tested an mRNA-based approach instead. Pigs with complete heart block received a single injection of mRNA coding for TBX18. The biological pacing effect lasted most of the four-week study, with regular day-night oscillations in heart rate and improved correlation between physical activity and heart rate, suggesting the induced pacemaker cells responded to the body’s own signals.

7Nature Biomedical Engineering. Transient pacing in pigs with complete heart block via myocardial injection of mRNA coding for the T-box transcription factor 18

More recently, researchers demonstrated that an adeno-associated virus (AAV) carrying TBX18, injected into rat ventricles, altered local gene expression to resemble that of the sinoatrial node and created automaticity at the injection site. These induced pacemakers responded to autonomic signals and increased maximal exercise tolerance, with the effect described as durable.

8PubMed Central. Biological pacemaker induced by focal cardiac transduction with AAV-TBX18

The AAV result is particularly interesting because AAV vectors persist much longer than adenoviruses in non-dividing cells like cardiomyocytes, which raises the possibility of a one-shot treatment that lasts years. That said, none of these biological pacemaker strategies have been tested in humans yet, and significant hurdles remain around long-term reliability and immune responses.

Stem Cells as Electrical Spare Parts

A parallel line of research uses stem cells to grow pacemaker-like cells in the lab, then transplant them into the heart. Researchers have derived sinoatrial-node-like cells from human induced pluripotent stem cells by carefully timing the delivery of developmental signals. These lab-grown cells fire pacemaker action potentials, respond to the body’s speed-up and slow-down chemical signals, and, when transplanted into the hearts of rats with atrioventricular block, demonstrated pacing activity in the host tissue.

9Frontiers in Bioengineering and Biotechnology. Bioengineering the Cardiac Conduction System: Advances in Cellular, Gene, and Tissue Engineering for Heart Rhythm Regeneration

The approach is attractive because, in principle, it could create a permanent biological pacemaker made of the patient’s own reprogrammed cells. But the gap between proof-of-concept animal experiments and a clinical product is wide. Challenges around getting the transplanted cells to mature properly, maintain their function over months and years, and avoid provoking an immune response remain significant barriers.

10PubMed Central. iPSC-Derived Biological Pacemaker-From Bench to Bedside

Researchers are also developing more sophisticated testing platforms to study these cells before attempting human trials. One group built a bioengineered atrial model by seeding decellularized rat hearts with human stem cell-derived atrial and sinoatrial nodal cells, then used light-sensitive tools to pace and study the resulting tissue.

11PubMed. Recellularized Humanized Bioengineered Biatrial Model for Arrhythmia, Biological Pacemakers, and Optogenetic Studies

Bridging Scar Tissue with Conductive Materials

After a heart attack, dead muscle is replaced by fibrous scar tissue that does not conduct electricity. This creates a roadblock in the heart’s wiring, forcing electrical signals to detour around the scar and sometimes loop back on themselves, triggering arrhythmias. Several research teams are developing conductive biomaterials designed to re-establish electrical continuity across these scars.

One approach uses injectable conductive hydrogels. A poly-pyrrole-chitosan hydrogel injected into rat heart scars seven days after a heart attack reduced tissue resistance by about 30%, improved electrical conduction across the scar by roughly a third, and doubled the amplitude of the electrical field potentials. The treated hearts showed resynchronized contraction.

12PubMed. The conductive function of biopolymer corrects myocardial scar conduction blockage and resynchronizes contraction to prevent heart failure

Another strategy takes the form of patches. A conductive cardiac patch inspired by the structure of fish swim bladders mimicked the heart’s natural anisotropy, meaning the tissue’s directional properties. In rat experiments, the patch improved electrical integration, reduced cell death and scarring, and promoted new blood vessel growth.

13PubMed Central. Cardiac-Adaptive Conductive Hydrogel Patch Enabling Construction of Mechanical-Electrical Anisotropic Microenvironment for Heart Repair

A more recent design uses conductive barbed microneedles that self-anchor to the heart wall and penetrate through the outer surface into the inner muscle, physically bridging non-infarcted tissue across the damaged zone to immediately re-establish electrical pathways.

14PubMed Central. A self-locking conductive cardiac patch for immediate electrical integration with infarcted rat myocardium

These conductive materials do not regenerate heart muscle. What they do is restore the electrical highway across a dead zone, which is sometimes enough to prevent the dangerous rhythm disturbances that scar tissue causes. All of these remain in animal testing, but the concept is compelling because it addresses one of the most common real-world causes of cardiac electrical failure: the aftermath of a heart attack.

Using Light to Control the Heartbeat

Optogenetics uses genetically encoded light-sensitive proteins to control electrical activity in cells that have been modified to express them. In the heart, this means you can pace or silence cardiac tissue with precisely targeted pulses of light rather than electrical shocks. A decade of cardiac optogenetics research has defined both near-term laboratory applications, like drug safety screening and personalized medicine assays, and longer-term aspirational goals for rhythm control therapy.

15PubMed Central. Cardiac optogenetics: a decade of enlightenment

In mouse experiments, optogenetic stimulation successfully increased heart rate to match the frequency of the light pulses, with only minor changes in blood pressure.

16Frontiers in Physiology. The physiological response during optogenetic-based cardiac pacing in awake freely moving mice

Perhaps more striking is the potential for arrhythmia termination. In mouse hearts engineered to express a light-sensitive channel, a single one-second pulse of blue light illuminating part of the ventricular surface terminated 97% of monomorphic ventricular tachycardias and 57% of the more chaotic polymorphic variety. Without light, none of those arrhythmias stopped on their own.

17European Heart Journal. Optogenetic termination of ventricular arrhythmias in the whole heart: towards biological cardiac rhythm management

The clinical path for optogenetics is steep. You would need to genetically modify enough heart tissue to respond to light, then implant a light-delivery device inside the chest. But as a painless alternative to the electric shocks that implantable defibrillators deliver, it is an appealing long-term vision. Patients with defibrillators often describe the shocks as extremely distressing, so a gentle pulse of light that accomplishes the same thing would be a major quality-of-life improvement.

Editing the Genetic Code Behind Faulty Wiring

Some electrical disorders are caused by a single mutation in an ion channel gene. Long QT syndrome, Brugada syndrome, and catecholaminergic polymorphic ventricular tachycardia all fall into this category. For these conditions, CRISPR-based gene editing offers the theoretical possibility of a permanent cure by correcting the mutation at its source.

Proof-of-concept work has shown that CRISPR can restore normal electrical behavior in patient-derived stem cell cardiomyocytes grown in the lab. Advances in base editing and prime editing, which make precise single-letter changes to DNA without cutting both strands, have enabled correction of disease-causing mutations in preclinical models with restoration of stable electrical activity and suppression of arrhythmias.

18Cardiology in Review. CRISPR/Cas9-Based Gene Editing for Correcting Inherited Channelopathies

A complementary approach targets the problem from the RNA level rather than the DNA level. MicroRNA-365 has been identified as a key regulator of the ion channels that control how long each heartbeat’s electrical signal lasts. In stem cell-derived heart cells from patients with long QT syndrome, inhibiting miR-365 normalized the pathologically prolonged electrical signal. Conversely, boosting miR-365 in cells from a short QT patient prolonged the signal. The effect held up in slices of adult human heart tissue, not just lab-grown cells.

19Nature Communications. MicroRNA-365 regulates human cardiac action potential duration

The microRNA approach has a different risk-benefit profile from CRISPR. It does not permanently alter the genome, which makes it potentially safer but also means the effect would need to be maintained with repeat dosing. For a condition like long QT syndrome, where the risk is sudden cardiac death, even a temporary treatment that can be repeated could be transformative.

Repairing the Connections Between Cells

Heart cells communicate electrically through gap junctions, clusters of protein channels that directly connect the interiors of neighboring cells. The most important of these proteins in the ventricles is connexin 43. When gap junctions malfunction, such as during the oxygen deprivation and subsequent blood-flow restoration that happen during a heart attack, electrical signals stall and arrhythmias can result.

Researchers found that during oxygen deprivation and reoxygenation, a protein called calmodulin binds to connexin 43 and shuts down gap junction communication. They designed a small peptide, SP15, that mimics the calmodulin-binding region of connexin 43 and blocks the destructive interaction. In isolated rat hearts subjected to simulated ischemia and reperfusion, SP15 improved electrical conduction parameters and reduced arrhythmia scores.

20Scientific Reports. Disrupting the interaction between connexin 43 and calmodulin restores gap junction function and mitigates reperfusion arrhythmias

This is early-stage work, but it targets a mechanism that contributes to a huge number of cardiac arrests: the arrhythmias that occur when blood flow is restored to oxygen-starved heart tissue, such as during treatment for a heart attack. If a peptide like SP15 could be given alongside reperfusion therapy, it might reduce the electrical chaos that often accompanies otherwise successful treatment.

Why the Heart Struggles to Heal Itself

One reason we need all these engineered solutions is that the adult human heart is remarkably bad at self-repair. Some vertebrates, like zebrafish, can regenerate heart muscle throughout life. Mammals appear to lose almost all of that capacity shortly after birth.

21PubMed Central. Mechanisms of Cardiac Regeneration

Even in newborn mice, the regenerative capacity is more limited than early reports suggested. After surgical removal of the heart’s apex in neonatal mice, regeneration occurred but was incomplete.

22PubMed Central. Limited Regeneration Potential with Minimal Epicardial Progenitor Conversions in the Neonatal Mouse Heart after Injury

This matters for the electrical system specifically because the conduction network is a tiny, specialized population of cells embedded in a much larger mass of working muscle. When disease or injury damages any part of that network, the body replaces it with scar tissue that cannot conduct. Understanding why mammals lose their regenerative ability so early in life is one of the big open questions in cardiac biology, and it explains why so many repair strategies rely on adding something from outside rather than coaxing the heart to fix itself.

The Evolutionary Roots of Cardiac Wiring

The heart’s conduction system is not a recent evolutionary invention layered on top of a simple pump. Studies comparing developing hearts across species have found that the molecular markers of the conduction system are conserved from lizards to mammals. The conduction system components found in adult mammals and birds most likely evolved from a shared ancestral building plan rather than arising independently in each lineage.

23PLOS ONE. Identifying the Evolutionary Building Blocks of the Cardiac Conduction System

This deep conservation is useful for repair research in a practical way. It means findings from zebrafish, mice, rats, and pigs are more likely to translate to humans because the basic genetic toolkit is shared. It also explains why genes like TBX18 work across species to reprogram cells into pacemaker-like tissue: the developmental instructions are ancient and deeply embedded.

Powering the Devices That Remain

Even as biological and genetic approaches advance, electronic devices will not vanish overnight. For the millions of people who will still need pacemakers and defibrillators, one persistent annoyance is the battery. Device replacements carry surgical risk, and battery life limits how small and durable these devices can be. Several groups are working on energy harvesters that convert the heart’s own motion into electricity.

Piezoelectric materials generate voltage when flexed. One design wraps a flexible porous piezoelectric film around a pacemaker lead in a dual-cantilever structure, harvesting energy from the lead’s motion with each heartbeat. The study suggested enough electrical energy could be converted from the lead’s movement, especially at the low frequencies typical of resting heart rates, to sustain device operation.

24Advanced Materials Technologies. Flexible Porous Piezoelectric Cantilever on a Pacemaker Lead for Compact Energy Harvesting

Another conceptual design explored fitting a piezoelectric harvester inside the battery compartment of a leadless pacemaker, effectively replacing the battery. The device generated 1.1 volts from simulated cardiac motion.

25PubMed Central. Conceptual Piezoelectric-Based Energy Harvester from In Vivo Heartbeats’ Cyclic Kinetic Motion for Leadless Intracardiac Pacemakers

No energy harvester has been successfully integrated into a commercial leadless pacemaker yet, largely because of size constraints and the challenge of generating enough power in such a small package.

26European Heart Journal. Piezoelectric energy harvesting for leadless pacing: a novel inertial energy harvester tuned to cardiac dynamics

A self-powered pacemaker that never needs a battery change would be a meaningful step for the patients who depend on these devices today, and it would also serve as an important bridge technology during the years or decades it takes for biological repair strategies to mature into standard treatments.