Coronary artery bypass grafting (CABG) and coronary stenting (PCI) are the main revascularization modalities in coronary artery disease today, and both are well-established techniques for the treatment of coronary artery disease in different coronary artery disease populations.
It is generally accepted that for most patients with acute ST-segment elevation myocardial infarction, emergency intracoronary intervention and stent placement is the preferred treatment strategy, whereas for patients with non-ST-segment elevation acute coronary syndrome and stable angina, the choice of revascularization depends on the complexity of the coronary lesion and the patient’s general and vital organ function. For patients with a SYNTAX score of less than 22, intervention is more effective than coronary artery bypass grafting, while for patients with a score of 23-32, the results and risks are comparable; for patients with a score of 33 or more, guidelines generally recommend coronary artery bypass grafting.
In reality, the general increase in per capita life expectancy and the improvement in the treatment of various geriatric diseases including coronary artery disease have resulted in both an increasing proportion of complex coronary artery disease and an increasing number of coronary artery disease patients of advanced age and with systemic multi-organ dysfunction (e.g., chronic obstructive pulmonary disease, cerebrovascular disorders, renal insufficiency, cardiac insufficiency, etc.). On the one hand, these patients are at high risk of coronary artery disease and are among those who benefit most from coronary revascularization, but on the other hand, due to the complexity of their coronary lesions, their advanced age and systemic multi-organ dysfunction, and the fact that a significant proportion of them have received one or more PCI or CABG revascularization treatments in the past, these patients are neither ideal candidates for interventional therapy nor for coronary revascularization in real life. Although minimally invasive coronary artery bypass grafting provides a ray of hope for the treatment of these patients, most of them still lack effective interventions and become patients who cannot undergo revascularization (NO OPTION). In recent years, some foreign medical centers have sporadically reported the use of various percutaneous cardiac assist devices for these patients, with good results.
What is a high-risk complex PCI procedure?
There is no unified definition of high-risk complex PCI, which should generally involve the following aspects: 1. Complex coronary lesions: multiple vascular lesions, tortuous travel, involvement of bifurcation, wall calcification, severe stenosis or even occlusion, only surviving single vessel lesions, or structural features such as aneurysmal dilatation, in-stent restenosis, bridge vessel lesions, or/and heavy thrombus load. 2. Multiple concomitant diseases: patients with coronary artery disease in addition to Presence of coronary artery disease, but also pulmonary infection, poor oxygenation, slow-onset lung, renal insufficiency, cerebrovascular disorders, 3. Advanced age, poor nutritional status, etc. 4. Poor cardiac function. Given the varying selection criteria in existing studies, it is inconvenient to define clinically which patients require circulatory assist devices, which assist devices to use, and when to activate them (preoperative prophylactic, intraoperative, and postoperative), and may also potentially adversely affect the effectiveness of various assist devices in controlled studies.
Effects of Interventional Therapy on Patients.
Interventional treatment can have two effects on patients: first: interventional treatment improves the patient’s myocardial ischemic condition and will improve the patient’s prognosis; however, the manipulation during interventional treatment and the complications of interventional treatment may also have some adverse effects on the patient’s cardiac function and hemodynamics.
During interventional treatment, plaque rupture, plaque displacement, acute thrombosis, thrombus dislodgement, difficulty in device pushing, and no or slow flow can occur throughout the PCI process, including repeated contrast injection, guidewire passage through the lesion, pre-dilated balloon pushing, balloon dilation, optional plaque rotation technique, during stent pushing and dilation, and after stent implantation. However, in patients with high-risk complex coronary artery disease, even transient myocardial ischemia due to flow blockade or increased cardiac load from contrast pushing can cause circulatory collapse and even serious consequences. In these patients, prophylactic use of circulatory assist devices can partially improve cardiac function, increase myocardial blood supply, and improve tolerance to myocardial ischemia. Most circulatory assist devices can maintain effective circulation in the unlikely event of circulatory collapse, ensuring smooth surgery and facilitating postoperative recovery.
Comparison of commonly used circulatory assist devices and their performance.
Commonly used circulatory assist devices can be divided into percutaneous circulatory assist devices and surgically implanted circulatory assist devices according to the implantation method. Percutaneous circulatory assist devices are the first assist devices considered and mainly include intra-aortic balloon counterpulsation (IABP), IMPELLA, extracorporeal membrane pulmonary oxygenator (ECMO), and TandemHeart.
IABP is the most widely used because of its early introduction, ease of operation, and moderate price. Its main effects are to increase diastolic blood pressure, increase cardiac perfusion, and decrease systolic blood pressure and reduce cardiac afterload, and its total hemodynamic effects are shown by increasing cardiac index and increasing early diastolic aortic pressure. elevation myocardial infarction; however, recent randomized controlled studies and meta-analyses have questioned its value in acute myocardial infarction and cardiogenic shock, in addition to guidelines that do not explicitly recommend IABP as an adjunct to high-risk complex coronary artery disease. In a randomized controlled study comparing prophylactic implantation of IABP versus conventional treatment before PCI in high-risk complex coronary artery disease (BCIS-1), there was no significant difference in the incidence of major adverse cardiac and vascular events between the two groups at 28 days after the procedure, although the number of procedure-related complications, including hypotension, was slightly higher in the prophylactic IABP implantation group than in the conventional treatment group.
The Impella device is a novel left ventricular assist device whose main mechanism of action is to pump oxygenated blood from the left ventricle into the ascending aorta via a hollow axial catheter inserted into the left ventricle, thereby reducing left cardiac afterload, increasing cardiac output, and improving coronary perfusion, and it is easy to learn and can achieve 2.5-5.0 L/min cardiac assisted pumping. Studies have shown that the device has a definite cardiac assist function in the rescue of cardiogenic shock and high-risk complex coronary artery disease.
The TandemHeart Percutaneous Ventricular Assist Device is an extracorporeal, dual-chamber, low-speed, centrifugal pump. It is a left atrial-femoral bypass system for short-term mechanical ventricular assist support that includes transatrial septal puncture placement, femoral artery placement, extracorporeal pump and external control system. Blood is pumped from the left atrium to an extracorporeal centrifugal pump to divert blood to the femoral artery on one or both sides. Its operation is more complex, and there are scattered reports of adjuvant therapy in high-risk complex coronary artery disease.
Extracorporeal membrane pulmonary oxygenation (ECMO) is another cardiopulmonary assist device, mostly used to provide circulatory and respiratory support in patients with heart failure and respiratory failure. Even through the femoral arterial route, this support has often required surgical incision in the past. However, recently developed ECMO systems can be established through percutaneous puncture, such as the Maquet Cardiohelp (NJ, USA) and Levitronix
(MA, USA). After placement of the tube (16-F), blood is drawn from the patient and then passed through a membrane oxygenation device. This membrane oxygenation device removes carbon dioxide from the venous blood and exchanges it with oxygen; the blood is then returned to the patient. There are currently two types of ECMO: veno-arterial (VA) and veno-venous (VV). However, cardiac support can only be provided through the VA type of ECMO.
ECMO can provide durable cardiac support in patients in cardiogenic shock when a left ventricular assist device from the surgical route cannot be implanted immediately; transition to a left ventricular assist device is often possible after circulatory support and oxygenation are re-established using ECMO. ECMO requires fluid perfusion and intensive anticoagulation as well as continuous intensive monitoring. In addition, the left ventricle is not directly unloaded and may actually be under some left ventricular load with ECMO support. eCMO usually requires specialized training of the team. Despite the lack of randomized clinical trials, there have been published case reports of the use of ECMO during high-risk PCI treatment.
Our institution has performed PCI using ECMO-assisted treatment for 32 patients with high-risk complex coronary artery disease since 2012, aged 72+/-11 years (46-93 years), with a 100% procedural success rate and 1-1095 days of follow-up, with significant improvement in clinical symptoms and cardiac function after the procedure and 6 deaths during the follow-up period, achieving good near- and mid- to long-term outcomes.
IABP
TandemHeart
TandemHeart
IMPELLA
Advantages.
Universal: available in most catheterization laboratories
Easy to use: easy to implant
Complete range of sizes: 7F, 7.5F, 8F; different volumes of balloons for different individuals
Safety: the use of fiber optic technology eliminates the risk of fluid flushing of the line
Convenience: automatic in vivo zero calibration
Improved: large capacity balloon enhances counterpulsation
Potential disadvantages.
Limited effect: only increases cardiac output by 0.3-0.5 L/min
Rhythm-dependent: counterpulsation depends on heart rhythm triggering
Risks: balloon displacement, rupture, air leak or sequestration, thrombus formation in the wall, arterial embolism (cholesterol, helium), stroke, infection, lower extremity ischemia, hemolysis, bleeding at the puncture site
Advantages.
Good efficacy: increases cardiac output by 4.5 L/min
Long maintenance time: several weeks
Not dependent on cardiac rhythm
Potential disadvantages.
Not enough equipment available
Non-pulsatile blood flow
Relative ischemia of the lungs
Alkalosis due to pulmonary hyperventilation
Risk of coronary vascular and cerebrovascular underperfusion
Sometimes concomitant IABP+/- positive inotropic drugs are required to maintain cardiac contractility to avoid left ventricular quiescence or distension, pulmonary hypertension, or intraventricular thrombosis
Risk of body circulation embolism, stroke, infection, lower extremity ischemia, hemolysis, and bleeding at the puncture site
Advantages.
Good efficacy: increases cardiac output by 4.0-5.0 L/min
Long maintenance time: 14 days
Not dependent on cardiac rhythm
Potential disadvantages.
Not widely enough equipped
Requires septal penetration and implantation of 21F catheter
Time consuming implantation procedure
Implantation cannot be performed during CPR
Relatively complex post-implantation maneuver
Risk of severe hypoxia due to displacement of the head of the left atrial cannula into the right atrium
17F femoral artery cannulation is prone to vascular complications
Risk of embolism, stroke, infection, hemolysis, and bleeding at the puncture site
Advantages.
Good efficacy: increases cardiac output by 2.5-4.0 L/min
Long maintenance time: 7 days
Not rhythm-dependent: but requires good left ventricular filling
Potential disadvantages.
Not widely enough equipped
Thick tube diameter: 12-14F, increased risk of vascular complications
Non-pulsatile blood flow
Potential for catheter inlet hole to slip from left ventricle to aorta
Risk of lower extremity ischemia with poor peripheral perfusion in overweight patients, risk of embolism in the circulation, stroke, infection, hemolysis, and bleeding at the puncture site
Considerations for performing high-risk complex coronary interventions using mechanical assisted circulation.
1, the use of circulatory assist devices for high-risk complex coronary interventions requires a joint agreement between cardiovascular physicians and cardiovascular surgeons, and collaborative surgical operations.
2. A thorough evaluation of the patient should be performed before treatment to confirm that there is no permanent irreversible damage to other vital organs throughout the body and that there is a greater hope that the cardiac vessels can be removed from circulatory assist support after completion of this blood flow reconstruction procedure, otherwise do not proceed with the procedure.
3. In May 2015, the American College of Cardiology, the American Society for Cardiothoracic Surgery and the Society for Hemodynamic Reconstruction Therapy and other professional academic institutions jointly issued an expert consensus on the use of percutaneous mechanical circulatory assist devices in the treatment of cardiovascular disease, which is a consensus for the presence of severe left ventricular insufficiency (EF less than 20-30%), complex lesions with a large coronary vascular supply, complex lesions with only a single vessel remaining The use of percutaneous circulatory assist devices may be considered when PCI is performed for severe three-vessel lesions.