We are excited to kick off a new series on The Catalyst where Shockwave’s Uday Illindala, Director of Clinical Engineering, answers common questions we receive from customers and addresses misconceptions about Intravascular Lithotripsy (IVL).
In this post, Uday explains the differences between Shockwaves and Ultrasound, as we are commonly asked if the shockwave generated by IVL is actually ultrasound. We hope you enjoy the series and find it informative!
Question: Can the Shockwave produced by IVL be classified as ultrasound?
Answer: By principles of physics, a shockwave is defined by:
- An abrupt change in pressure and having a velocity higher than the speed of sound in the medium it propagates
- Single pulse with a wide range of frequencies (150KHz – 100MHz), high pressure amplitude, very short pulse width and a short rise time (nanoseconds)
Shockwaves produced by IVL is in a similar range up to a few MHz (<10 MHz) with the majority in the sonic acoustic range (see graphs below).
On the other hand, ultrasound wave is required to be a continuous wave propagating with a frequency in the ultrasound range (20kHz – 200+MHz). Ultrasound for medical purposes is in the range of 1MHz – 40MHz, typically focused on a single frequency within that range. All particles of the medium subjected to the wave are at the same frequency.
Figure 1 (Above, Left) and Figure 2 (Above, Right)
In conclusion, IVL uses shockwaves, and not ultrasound or ultrasonic waves, to modify calcium. IVL works because the shockwaves create an abrupt change in pressure that cracks both intimal and medial calcium in the cardiovascular system, which couldn’t be done with ultrasound. Also, we know IVL operates in the sonic acoustic range because we can hear the “tick-tick” sound of the emitters firing, creating the shockwaves, which makes IVL the powerful technology that it is.
Sources for Images
Fig 1: http://physics.info/shock/
Important Safety Information
Caution: Federal law (USA) restricts this device to sale by or on the order of a physician.
Indication for Use – The Shockwave Medical Intravascular Lithotripsy (IVL) System is intended for lithotripsy-enhanced balloon dilatation of lesions, including calcified lesions, in the peripheral vasculature, including the iliac, femoral, ilio-femoral, popliteal, infra-popliteal, and renal arteries. Not for use in the coronary or cerebral vasculature.
Contraindications – Do not use if unable to pass 0.014 guidewire across the lesion • Not intended for treatment of in-stent restenosis or in coronary, carotid, or cerebrovascular arteries.
Warnings – Only to be used by physicians who are familiar with interventional vascular procedures • Physicians must be trained prior to use of the device • Use the Generator in accordance with recommended settings as stated in the Operator’s Manual
Precautions – Use only the recommended balloon inflation medium • Appropriate anticoagulant therapy should be administered by the physician • Decision regarding use of distal protection should be made based on physician assessment of treatment lesion morphology
Adverse Effects – Possible adverse effects consistent with standard angioplasty include: • Access site complications • Allergy to contrast or blood thinners • Arterial bypass surgery • Bleeding complications • Death • Fracture of guidewire or device • Hypertension/Hypotension • Infection/sepsis • Placement of a stent • Renal failure • Shock/pulmonary edema • Target vessel stenosis or occlusion • Vascular complications. Risks unique to the device and its use: • Allergy to catheter material(s) • Device malfunction or failure • Excess heat at target site
Prior to use, please reference the Instructions for Use for more information on indications, contraindications, warnings, precautions, and adverse events. www.shockwavemedical.com