Fractional Flow Reserve Measurement For Assessing Coronary Stenosis

Coronary Heart Disease which occurs as a result of atherosclerotic plaque-build up in the inner walls of coronary arteries is a common heart ailment that has been affecting millions of people worldwide. The field of cardiac science and interventional cardiology has been striving hard to devise an optimal approach to manage coronary artery disease (CAD).  Evaluating the physiological significance and severity of lesions is a challenging factor in most cases which is why pressure-based Fractional Flow Reserve measurement method was introduced. FFR provides a well-validated index in deciding between coronary stenting and medical therapy. Thses days, it is considered an indispensable clinical tool in the catheterization laboratory.

Pressure-based Fractional Flow reserve measurement provides the ratio of normal blood flow to the maximum achievable blood flow in the same coronary artery, given the maximal vasodilated condition. Lesions that measure a FFR value of less than 0.75 need percutaneous coronary intervention (PCI) with stenting, while lesions of a value higher than 0.75 should be managed with pharmacological treatment. Minimally invasive FFR technique possesses several special features that make it a gold standard for diagnosis in the catheterization laboratory. A well-defined cut-off value, unequivocally normal value for every patient and narrow gray zone are some of the major characteristics. Fluoroscopy guided pullback pressure recording performed during the catheterization proves to be a great tool in obtaining detailed spatial information and evaluating the hemodynamic effect of stenoses. The sensor placed in the distal coronary artery during FFR procedure is simply pulled back under fluoroscopic guidance to measure the pressure levels across the blood vessel. Helping the interventional cardiologist to assess the extent of lesions and exact location of the pressure drop, fluoroscopy guided pullback pressure recording proves to be a great diagnostic tool for different patient subsets.

Bifurcation lesions that involve the proximal main vessel, the distal main vessel and the side branch are one of the most challenging lesion subsets. Associated with restenosis, greater complications and lower success rates, severe coronary artery bifurcation lesions pose a major challenge for the interventional cardiologists. PCI is not considered as a favourable approach to treat the symptomatic coronary artery bifurcation lesions. However, with the advent of fractional flow reserve method and pullback pressure measurements, FFR guided PCI assures excellent results and safer outcomes.

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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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