Left Main Coronary Artery Stenting – Is it a Safe Approach?

Common coronary heart disease (CHD) also to referred as ischemic heart disease is the leading cause of heart attacks and angina. Atherosclerotic plaque build-up in the inner walls of coronary arteries hardens the blood vessels and restricts the blood supply to heart. Lack of oxygen leads to the damage or death of heart tissues which results in ischemia. Clots in the arteries can be life-threatening, as it eventually restricts or completely cuts off the oxygen-rich blood supply resulting in angina or myocardial infarctions (heart attacks). Some of the common coronary heart disease symptoms include sharp pain or pressure in the chest that travels to the arms and jaw, shortness of breath, light-headedness and fatigue. Even if the symptoms are mild, seeking immediate medical attention is necessary.

The left main coronary artery (LMCA) is responsible for supplying blood to a large segment of the myocardium and stenosis of LMCA will lead to acute cardiac events. Coronary Artery Bypass Graft (CABG) has been considered the standard therapeutic option for treating left main coronary artery disease (LMD), because it provides better survival rates when compared to drug therapy. Percutaneous coronary intervention (PCI) with bare metal stents tended to result in in-stent restenosis and a need for revascularization, making it a risky choice. But with the advent of state-of-the-art catheterization technologies, drug-eluting stents and antithrombotic agents, newer left main coronary artery stenting has made it a viable option for patients with high surgical risks or co-morbidities.

Ongoing clinical trials and research studies have been evaluating the effectiveness of using drug-eluting stents (DES) for Unprotected LMCA compared with CABG. Targeted lesion revascularization advantages of minimally invasive newer left main coronary artery stenting can be considered as a safe and effective alternative to CABG, especially for patients in a high-risk group. Even though DES is considered as a great step in interventional cardiology, concerns over the polymer-associated complications and risk of thrombosis have raised questions about its safety. Drug-eluting stent thrombosis is closely associated with acute myocardial infarction resulting in mortality and morbidity. Biocompatible and bioabsorbable stents that are developed in order to overcome issues such as drug-eluting stent thrombosis is a recent development in the interventional community that offers a promising approach for PCI in treating left main coronary artery disease. But in the meantime, cardiologists have to choose either PCI or CABG to manage the left main disease based on the SYNTAX score and medical-surgical consultation. 

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Advanced Diagnostic & Treatment Options for Cardiac Artery Disease Management

Stress testing is a widely used non-invasive diagnostic method that provides reliable information about the severity of symptomatic cardiac artery disease or coronary artery disease (CAD). As the name indicates, stress testing is carried out by putting the body under physical stress. A myocardial perfusion scan is a combined procedure that combines stress testing and a nuclear heart scan.

Myocardial perfusion scan is a non-invasive cardiac imaging method that is performed during rest and stress. For the stress testing, patients are injected with a radioactive tracer during the exercise (running on a treadmill). Radionuclide which circulates through the blood stream will show the possible damages and blockages present in the heart muscle. During the stress testing, the patient will be continuously monitored by keeping track of heart rate, blood pressure and ECG changes. Pharmacologically-induced stress testing is opted in some cases, when the patients can’t exercise on a treadmill due to medical conditions. Medications are injected to make the coronary arteries dilate and promote vasodilatation. Non-invasive adenosine myocardial perfusion is a case in point. A resting scan will be performed after some hours to compare the heart functioning and blood flow. The risk of this diagnostic procedure is often associated with the stress part of the test which may lead to rare instances of adverse cardiac events. 

When it comes to cardiac or coronary artery disease treatment, percutaneous coronary intervention or PCI (angioplasty and stenting) and coronary artery bypass graft (CABG) surgery are the standard options. Cardiologists rely on the catheterization lab results and reports to devise the right treatment plan. With tremendous advancements in the interventional and catheterization procedures, PCI has gained wide interest among the medical community. Not only it is not as aggressive as CABG, but it also cuts down the recovery time and treatment costs. 

The novel idea of fully degradable bioresorbable stents that can overcome the major limitations of bare metal stenting (BMS) and drug-eluting stenting (DES) has also been fascinating the interventional community from a long time. Bioresorbable or bioabsorbable stents are supposed to improve the endothelium function during a critical period. When no longer needed, it will be bioabsorbed to the body thereby negating the risks of thrombosis and the need for antiplatelets therapy. Clinical trials and experiments are still going on and until then drug eluting stents and bypass surgery remain the preferred revascularization procedures.

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Fractional Flow Reserve Measurements in the Management of Acute Coronary Artery Syndrome

Cardiovascular diseases are a leading cause of mortality and morbidity around the world. Coronary artery disease (CAD), commonly known as heart disease is the end product of atherosclerotic plaque formation. High blood pressure, smoking or high cholesterol levels are some of the risk factors that worsen the atherosclerotic condition. Stable angina and acute coronary artery syndrome (ACS) are the two main sub categories of clinical patterns produced by CAD. Coronary arteries that harden up due to the atherosclerosis limit the blood supply to the heart, thereby damaging the myocardial tissues (ischemia). Rupture of a vulnerable plaque causes occlusive intracoronary thrombus which further leads to the complete obstruction of blood supply, resulting in unstable angina or myocardial infarctions (heart attacks). Even though chest pain (angina) and discomfort are considered as the common symptoms of CAD, it is essential to perform the diagnostic procedures in order to distinguish patients with Acute Coronary artery syndrome. Prompt medical attention and diagnosis is crucial for treating the ACS patients as it is the major cause of infarctions.

Cardiac conditions with clinical patterns that represent myocardial infarctions and unstable angina fall into the category of ACS. Unstable angina, Non-ST-segment elevation myocardial infarction (NSTEMI) and ST-segment elevation myocardial infarction (STEMI) are the main classifications of ACS, diagnosed with the help of electrocardiograms (ECG) and blood tests. Devising a risk stratification method is possible only with in-vivo evaluation of the vulnerable plaque. Advanced medical imaging techniques such as intravascular ultrasound (IVUS), angioplasty surgery and optical coherence tomography (OCT) helps in assessing the pathophysiology of plaque formation, erosion and rupture. Treatment of acute coronary artery syndrome mainly involves medical therapy and revascularization procedures. Anti-ischemic agents, anti-platelet agents and anti coagulants are the standard pharmacological treatment options prescribed by physicians. Revascularization procedures include percutaneous coronary intervention (PCI) and Coronary Artery Bypass Graft (CABG). Fractional Flow Reserve guided percutaneous intervention helps the cardiologist determine whether to treat the lesions with stenting or medical therapy. The patient’s cardiac health, risk score and several other factors are taken into consideration to choose between and bypass and angioplasty surgery. 

Huge advancements have been made in evaluating the extent and severity of culprit lesions of ACS which helps in the effective management of the condition. Novel antiplatelet drugs, pressure wire guided percutaneous interventions, fractional flow reserve and drug eluting stent implantations are some of the noteworthy achievements. 

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Management of Atrial Fibrillation

The human heart is a muscular pump which beats as a result of electrical impulses produced by a special group of cells in the heart that have the ability to generate electrical activity on their own. Any abnormalities in the heart rate or rhythm can be considered to be a fault in the electrical conduction system of the heart. If the heart rate remains constantly slower (bradycardia) or faster (tachycardia) with irregular rhythm, then it may be a heart condition called arrhythmia. Diagnosis of arrhythmia involves collecting information about symptoms, evaluating medical history and a physical exam. Electrocardiogram, cardio monitoring and blood flow blood pressure measurements are some of the diagnostic tests, blood pressure and procedures performed to identify the underlying cause of abnormal heart rhythms.

Atrial fibrillation or A-fib (AF) is a type of arrhythmia that happens when the electrical signals are not only generated from sinus node, but are also generated from different places in and around the right atrium. When the atrioventricular node (AV node) – the electrical relay station between the upp and lower chambers of the heart-- is flooded with multiple erratic signals  it leads to twitching of atria and desynchronised contractions of heart chambers. There are mainly three types of atrial fibrillation - Paroxysmal Atrial Fibrillation, Persistent Atrial Fibrillation and Permanent Atrial Fibrillation. Whenever the A-fib lasts from a few seconds to about a week, it is termed as Paroxysmal Atrial Fibrillation and when the A-fib episode continues for more than seven days, the condition is called persistent atrial fibrillation. When the abnormal heart rhythm persists all the time, it is called permanent atrial fibrillation. Both the paroxysmal and persistent AF can progress to permanent AF over a period of time, which is why it is highly recommended to seek treatment as early as possible.  

AF episodes cause a disruption in the blood flow thereby increasing the likelihood of blood clot formation.  That is why risk of acute cardiovascular events and strokes are higher among people with atrial fibrillation. Treatment of Afib aims in cutting down the risk of blood clot formation and restoring the normal heart rhythm. Medical therapy using anticoagulants and electrical interventions are performed to treat this heart condition. Electro cardioversion, catheter ablation and surgical pocket maze are the standard procedures opted by the cardiologists to treat arrhythmias. In some cases, ablate and pace approach is recommended. During this procedure, the AV node is destroyed and an artificial pacemaker is placed in the surgical pocket of the chest to ensure a regular backup rhythm. Choosing between pharmacological treatment and ablation procedures always comes down to factors such as degree of AF episodes, cardio health and evaluation of surgical complications.

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Recent Advances in Cardiac Electrophysiology

Cardiology, being a prime medical speciality has always been in the forefront of inventing new diagnostic techniques, medical therapies, interventional procedures, medical imaging, continuous monitoring systems and more.  Among the many recent advancements, leadless pacemaker and thermocool smarttouch catheter offer a promising approach in treating problems with the heart's electrical conduction system.

Thermocool Smarttouch catheter: In a healthy heart, the electrical impulses are generated from the sinoatrial (SA) node which controls the speed or rhythm of beats. Any disruption or error in this conduction process leads to arrhythmia resulting in either too fast heart rate or too slow heart rate. Cardiac ablation is a medical procedure that is often preferred by the physicians to treat arrhythmias for those patients who don’t respond positively to drug therapy. During this catheterization procedure, continuous monitoring and radio frequency energy is used to scar the sources of abnormal heart rhythms. However, the procedure can fail sometimes because of inadequate lesion formation. Thermocool smarttouch catheter – an innovative discovery in electrophysiology focuses to resolve this drawback as it is integrated with contact-force sensing technology to provide detailed evaluation of catheter-to-myocardial contact force and catheter stability. This will guide the physicians to apply the stable force to the tissues without any risk of injury or complications.

Leadless pacemaker:Cardiologists have been recommending pacemakers for most of the patients suffering with bradyarrhythmias (too slow heart beat) or heart block. Taking over the job of the SA node, this electrical device restores electrical conduction through the heart. A surgical incision has to be made in the chest to place the pacemaker. Leads are connected to it which acts as a conduit for the delivery of electrical pulses that stimulate the heart functioning. However, acute and chronic complications arise whenever the surgical pocket is infected or leads are displaced. That is why leadless pacing technologies have gained immense interest in the field of cardiology. Self-contained leadless pacemakers that are different from its conventional counterparts don’t require any surgical incision or leads and can be placed through a catheterization procedure. Trial results and findings support the use of this less-invasive pacemaker technology.

It can be said that the future of interventional cardiology and electrophysiology looks bright and ensures to improve the quality of patient’s life.

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