style="font-size:15px;"> 82 82 Musto C, De Felice F, Rigattieri S, et al. Instantaneous wave‐free ratio and fractional flow reserve for the assessment of nonculprit lesions during the index procedure in patients with ST‐segment elevation myocardial infarction: The WAVE study. Amer Heart Jnl 2017; 193:63–9. doi:10.1016/j.ahj.2017.07.01783 83 Thim T, Gotberg M, Frøbert O, et al. Nonculprit Stenosis Evaluation Using Instantaneous Wave‐Free Ratio in Patients With ST‐Segment Elevation Myocardial Infarction. JACC: Cardiovascular Interventions 2017; 10:2528–35. doi:10.1016/j.jcin.2017.07.021
84 84 Davies JE, Sen S, Dehbi H‐M, et al. Use of the Instantaneous Wave‐free Ratio or Fractional Flow Reserve in PCI. N Engl J Med 2017; 376:1824–34. doi:10.1056/NEJMoa1700445
85 85 Petraco R, van de Hoef TP, Nijjer S, et al. Baseline instantaneous wave‐free ratio as a pressure‐only estimation of underlying coronary flow reserve: results of the JUSTIFY‐CFR Study (Joined Coronary Pressure and Flow Analysis to Determine Diagnostic Characteristics of Basal and Hyperemic Indices of Functional Lesion Severity‐Coronary Flow Reserve). Circulation Cardiovascular Interventions 2014; 7:492–502. doi:10.1161/CIRCINTERVENTIONS.113.000926
86 86 van de Hoef TP, van Lavieren MA, Damman P, et al. Physiological basis and long‐term clinical outcome of discordance between fractional flow reserve and coronary flow velocity reserve in coronary stenoses of intermediate severity. Circulation Cardiovascular Interventions 2014; 7:301–11. doi:10.1161/CIRCINTERVENTIONS.113.001049
87 87 Lee JM, Hwang D, Park J, et al. Physiologic mechanism of discordance between instantaneous wave‐free ratio and fractional flow reserve: Insight from 13N‐ammonium positron emission tomography. International Journal of Cardiology 2017; 243:91–4. doi:10.1016/j.ijcard.2017.05.114
88 88 JM L, TM R, KH C, et al. Clinical Outcome of Lesions With Discordant Results Among Different Invasive Physiologic Indices ‐ Resting Distal Coronary to Aortic Pressure Ratio, Resting Full‐Cycle Ratio, Diastolic Pressure Ratio, Instantaneous Wave‐Free Ratio, and Fractional Flow Reserve. Circulation Journal: Official Journal of the Japanese Circulation Society 2019; 83:2210–21. doi:10.1253/circj.CJ‐19‐0230
89 89 Pijls NHJ, Klauss V, Siebert U, et al. Coronary pressure measurement after stenting predicts adverse events at follow‐up: a multicenter registry. Circulation 2002; 105:2950–4.
90 90 Hakeem A, Ghosh B, Shah K, et al. Incremental Prognostic Value of Post‐Intervention Pd/Pa in Patients Undergoing Ischemia‐Driven Percutaneous Coronary Intervention. JACC: Cardiovascular Interventions 2019; 12:2002–14. doi:10.1016/j.jcin.2019.07.026
91 91 Jeremias A, Davies JE, Maehara A, et al. Blinded Physiological Assessment of Residual Ischemia After Successful Angiographic Percutaneous Coronary Intervention: The DEFINE PCI Study. JACC: Cardiovascular Interventions 2019; 12:1991–2001. doi:10.1016/j.jcin.2019.05.054
92 92 Boden WE, O'Rourke RA, Teo KK, et al. Optimal medical therapy with or without PCI for stable coronary disease. N Engl J Med. 2007; 356:1503–16. doi:10.1056/NEJMoa070829
93 93 Cohen DJ, Van Hout B, Serruys PW, et al. Quality of life after PCI with drug‐eluting stents or coronary‐artery bypass surgery. N Engl J Med. 2011; 364:1016–26. doi:10.1056/NEJMoa1001508
94 94 Abdallah MS, Wang K, Magnuson EA, et al. Quality of Life After PCI vs CABG Among Patients With Diabetes and Multivessel Coronary Artery Disease: A Randomized Clinical Trial. JAMA 2013; 310:1581–90. doi:10.1001/jama.2013.279208
95 95 Ford TJ, Berry C. How to Diagnose and Manage Angina Without Obstructive Coronary Artery Disease: Lessons from the British Heart Foundation CorMicA Trial. Interv Cardiol 2019; 14:76–82. doi:10.15420/icr.2019.04.R1
96 96 Kunadian V, Chieffo A, Camici PG, et al. An EAPCI Expert Consensus Document on Ischaemia with Non‐Obstructive Coronary Arteries in Collaboration with European Society of Cardiology Working Group on Coronary Pathophysiology & Microcirculation Endorsed by Coronary Vasomotor Disorders International Study Group. Euro Heart J. 2020; 388:1459–21. doi:10.1093/eurheartj/ehaa503
97 97 Thomas J Ford MHF, Bethany Stanley M, Richard Good MD, et al. Stratified Medical Therapy Using Invasive Coronary Function Testing In Angina: CorMicA Trial. J Am Coll Cardiol. 2018; :1–53. doi:10.1016/j.jacc.2018.09.006
98 98 Kobayashi Y, Fearon WF. Invasive coronary microcirculation assessment‐‐current status of index of microcirculatory resistance. Circulation Journal : Official Journal of the Japanese Circulation Society 2014; 78:1021–8. doi:10.1253/circj.cj‐14‐0364
99 99 Yong AS, Layland J, Fearon WF, et al. Calculation of the Index of Microcirculatory Resistance Without Coronary Wedge Pressure Measurement in the Presence of Epicardial Stenosis. JACC: Cardiovascular Interventions 2013; 6:53–8. doi:10.1016/j.jcin.2012.08.019
CHAPTER 8
Intravascular Ultrasound: Principles, Image Interpretation, and Clinical Applications
Adriano Caixeta, Akiko Maehara, and Gary S. Mintz
Medical uses of ultrasound came shortly after the end of World War II. However, real‐time ultrasound imaging originated in the late 1960s and early 1970s when Bom et al. [1] pioneered the development of linear array transducers for use in the cardiovascular system. The first two‐dimensional catheter imaging system was designed in 1972 using a solid‐state transducer array of 32 elements arranged radially at the tip of a 9 Fr catheter [2]. By the late 1980s, Yock et al. [3] had successfully miniaturized a single‐transducer system that could be placed within coronary arteries. Ever since, intravascular ultrasound (IVUS) has become an increasingly important catheter‐based imaging technology providing both practical guidance for percutaneous coronary interventions (PCI) as well as many different clinical and research insights [4,5]. IVUS directly images the atheroma within the vessel wall, allowing reproducible measurement of plaque size, distribution, and to some extent its composition.
Principles of IVUS imaging
Ultrasound is acoustic energy with a frequency above human hearing. The highest frequency that the human ear can detect is approximately 20 thousand cycles per second (20 000 Hz). This is where the sonic range ends and where the ultrasonic range begins. In medical imaging, high‐frequency acoustic energy is the range of millions of cycles per second (megahertz; MHz).
IVUS supplements angiography by providing a tomographic perspective of lumen geometry and vessel wall structure. The equipment required to perform intracoronary ultrasound consists of a catheter incorporating a miniaturized transducer and a console to reconstruct the images. The IVUS transducer converts electrical energy into acoustical energy through a piezo‐electric (pressure‐electric) crystalline material that expands and contracts to produce sound waves when electrically excited (i.e. a series of pulse/echo sequences or vectors). After reflection from tissue, part of the ultrasound energy returns to the transducer; the transducer then generates an electrical impulse that is converted into moving pictures [6]. All materials in the body reflect sound waves. Sound waves bounce back at various intervals depending on the type of material and the distance from the transducer. It is the variation in reflective sound waves that creates the ultrasound image on the console.
The intensity of reflected (or backscattered) ultrasound depends on a number of variables including the intensity of the transmitted signal, the attenuation of the signal by the tissue, the distance from the transducer to the target, the angle of the signal
