Category Archives: Vascular

Can We Use Ultrasound to Pace the Heart?

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In a Heartbeat

What would it take to get back a heartbeat?

We hear about cardiovascular diseases (CVDs) all the time, with an estimated 31% of deaths globally1. It’s not uncommon to hear stories about a close friend who was young and had a heart attack. Perhaps your mom or dad had a stroke or even a neighbor who is having heart rhythm issues.

Every time I think about CVDs, the first thing that comes to my mind is my uncle. He was a healthy man in his 60s, very athletic, he used to swim and participate in marathons all the time. He never smoked, he always had a healthy diet and was active, and bam! One day, he had a stroke. To make the long story short, he ended up having to have a pacemaker implanted. He had a complication due to a pacemaker lead that was dispositioning, which caused a subsequent ischemic stroke.

Don’t take me wrong, pacemakers can be a good solution. However, complications like broken leads for instance can cause unnecessary “shocks” to the user. Complications that may occur during surgery include allergic reactions, infections, vessel damage, and heart tissue punctures.2 The weakest link in the pacemaker system, most often leading to complications, is the lead. This poses a question: Can we use an alternative source of energy to pace the heart? Can we use ultrasound as an alternative source of energy? Can we use ultrasound to treat CVDs?

If you would have a choice of another way to “control” the heart, would you do it in a heartbeat?

Cardiac Pacing

Looking back, if there was another way to pace my uncle’s heart and bring him back to a normal life, of course I would do it. Pacemakers work only when needed. If your heartbeat is too slow (bradycardia), the pacemaker sends electrical signals to your heart to correct the beat. The same principle is used if your heart is too fast (tachycardia). The pacemaker has a battery, and it works with electric energy. My goal in the last 10 years or so has been to use ultrasound as an alternative source of energy to pace the heart and to treat cardiovascular diseases.

The first step was to investigate if the ultrasound pulses can increase or decrease the heart rate (HR). Some of my preliminary studies3-5 showed that ultrasound applied to the heart of rats can cause a negative chronotropic effect (or decrease in the heart rate; Figure 1). The ultrasound protocol uses a sequence of different parameters, such as pulse duration (PD), pulse repetition frequency (PRF), etc. The PD is the distance each pulse travels and the pulse repetition frequency is the rate at which the transducer emits the pulses. The pulses must be spaced. This allows enough time between pulses, so the beam has enough time to reach the target and return to the transducer before the next pulse is generated. With a specific sequence, I was able to decrease the heart rate. Voila!

Figure 1: The top image is the baseline before ultrasound application (HR = 322 BPM), then 3 minutes after ultrasound application (HR = 230 BPM), and 15 minutes after (HR = 223 BPM).

But what if I can increase the heart rate using ultrasound pulses? In a recent investigation, I was also able to increase the heart rate with a specific sequence of ultrasound pulses (Figure 2).

Figure 2: HR at various points before, during, or after ultrasound application (points are not linearly spaced). An increase in HR was observed during each increased PRF sequence (1st, 2nd, and 3rd PRF).6

Is the Future Wireless?

We are all experiencing changes in gadgets in our daily life, from wireless vacuums to earplugs, chargers, etc. But can we pace the heart without leads? The question remains such as my uncle’s story. He’s still an active guy, but of course he needs to avoid problems like electromagnetic interference (cell phones, metal detectors, etc). Can we have a therapy that uses ultrasound to pace the heart, that is non-invasive, wireless, safe, and feasible? I hope so. Maybe one day I can change this scenario in a heartbeat!

References

1. World Health Organization. Fact Sheets: Cardiovascular Disease. Accessed: July 13, 2020. [Online]. Available: https://www.who.int/en/news-room/fact-sheets/detail/cardiovascular-diseases-(cvds)

2. Pakarinen S, Oikarinen L, and Toivonen L. Short-term implantation related complications of cardiac rhythm management device therapy: A retrospective single-centre 1-year survey. Europace 2010; 12:103–108. doi: 10.1093/europace/eup361.

3. Coiado OC and O’Brien WD. The negative chronotropic effect in rat heart stimulated by ultrasonic pulses: Role of sex and age. J Ultrasound Med 2017; 36:799–808.

4. Coiado OC and O’Brien WD. The role of the duty factor in ultrasound-mediated cardiac stimulation. J Acoust Soc Am 2014; 136:EL231–EL235.

5. Coiado OC, Buiochi E, and O’Brien W. Ultrasound-induced heart rate decrease: Role of the vagus nerve. IEEE Trans Ultrason Ferroelectr Freq Control 2015; 62:329–336.

6. Coiado OC, Yerrabelli RS, Christensen AP, Wozniak M, Lucas A, O’Brien WD Jr. Positive chronotropic effect caused by transthoracic ultrasound in heart of rats. JASA Express Lett 2021; 1:08200.

Dr. Coiado, PhD, is a Teaching Associate Professor in both the Carle Illinois College of Medicine and the Bioengineering Department at the University of Illinois at Urbana-Champaign. At Carle Illinois College of Medicine, she acts as the Director of Student Research and Discovery Learning. Her research interests focus on cardiovascular studies, acoustics, bioinstrumentation, and education.

Interested in reading more about vascular ultrasound? Check out these resources:

Deep Vein Thrombosis

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Deep vein thrombosis (DVT) is the formation of a blood clot in a deep vein, most commonly in the legs, thigh, or pelvis. If the superficial veins (the veins close to the surface) developed a thrombus, the condition is called thrombophlebitis. The most common life-threatening concern with DVT is the potential for a clot to detach, travel through the inferior vena cava (IVC) to the right side of the heart and become stuck in pulmonary arteries that supply blood to the lungs, causing a serious medical condition called a pulmonary embolism (PE). Both DVT and PE are considered to be part of the same overall disease process, which is called venous thromboembolism (VTE). VTE can occur as an isolated DVT or as PE with or without DVT. The most frequent long-term complication is post-thrombotic syndrome (PTS), which can cause pain, swelling, a sensation of heaviness, itching, and in severe cases, venous ulcers.

B-Mode image of the left common femoral vein showing a thrombus lodged inside its lumen (arrow).

Do you feel pain or tenderness and have swelling, warmth, dilation of surface veins, and redness or discoloration of the legs, thigh, or pelvis? That may be deep vein thrombosis, which is the formation of a blood clot in a deep vein. Do you know that some DVT patients have no symptoms? Yes, signs and symptoms alone are not sufficiently sensitive or specific to make a diagnosis, but when considered in conjunction with pre-test probability, can help you and the referring physician to determine the likelihood of DVT. You may not know that in most suspected cases, DVT is ruled out after evaluation, and symptoms are more often due to other causes that mimic DVT but it is not, such as a ruptured cyst that is called Baker’s cyst located at the back of your knee joint, infection or inflammation of your skin known as cellulitis, blood collection called hematoma, obstruction of your leg lymph vessels called lymphedema, and presence of varicose veins. Other causes include tumors, venous or arterial dilatation known as aneurysms, and connective tissue problems.

If you have trauma to a leg, sitting still for a long time (immobilization), and/or you have an underlying blood disorder (coagulopathy) can make you more likely to develop a DVT. Some medicines and disorders that increase your risk for blood clots can also lead to DVTs. The mechanism of clot formation typically involves some combination of decreased blood flow rate, increased tendency to clot, and injury to the blood vessel wall. You would need to see your physician if you have risk factors that increase your chances of developing DVT such as recent surgery, older age, active cancer, obesity, personal history and family history of VTE, trauma, injuries, lack of movement, hormonal birth control, pregnancy and the period following birth, genetic components, and a few blood disorder syndromes.

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Color flow imaging showing blood flow in the popliteal vein (blue) and popliteal artery (red).

When you visit your physician, he or she will able to evaluate you by applying a clinical probability assessment, which might determine whether you are “likely” or “unlikely” to have DVT. In those unlikely to have DVT, a diagnosis is excluded by a negative D-dimer blood test. In people with likely DVT, ultrasound is the standard imaging used to confirm or exclude a diagnosis. The sonographer will put ultrasound gel on the area and apply gentle probe pressure along the whole of your lower limb starting from the groin region to the ankle level. Ultrasound is the standard diagnostic method because it is safe, inexpensive, consumes a short amount of time, and is highly sensitive for detecting an initial DVT. You will be considered positive for DVT when the vein walls of normally compressible veins do not collapse under gentle ultrasound probe pressure. Moreover, the sonographer might apply color flow Doppler to further characterize the clot and he or she can use Doppler ultrasound to further assess the non-compressible pelvic veins. Please keep in mind that cross-sectional imaging using computed tomography venography (CTV) and magnetic resonance venography (MRV) are also diagnostic possibilities. The gold standard for judging imaging methods is contrast venography, which involves injecting a peripheral vein of the affected limb with a contrast agent and taking X-rays to reveal whether the venous supply has been obstructed. Because of its cost, invasiveness, limited availability, and other limitations, this test is rarely performed nowadays.

You would need to see your physician if you are confirmed to have DVT to seek treatment and prevention and resume normal life. Treatment includes medicines to ease pain and inflammation, break up clots, and keep new clots from forming. Keeping the affected area raised and applying moist heat can also help. If you are taking a long car ride or flight, take a break, walk or stretch your legs, and drink plenty of liquids. Prevention of VTE for the general population includes avoiding obesity and maintaining an active lifestyle.

Dr Akram Asbeutah

Dr. Akram Asbeutah, PhD, DMU-ASUM, ASAR, ASA, AIUM, SVU, AIR, ASRT, RT(R) ARRT, is a Clinical Associate Professor in the Department of Radiologic Sciences at the Faculty of Allied Health Sciences, Kuwait University & Monash University-Melbourne, Australia.

Interested in learning more about vascular ultrasound? Check out the following posts from the Scan:

Do It With Heart: Pre-Intubation Point-of-Care Echocardiography for Hemodynamic Optimization

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Have you ever wondered why that patient coded after endotracheal intubation? As it turns out, it is not uncommon after critically ill patients are intubated. Approximately 60% of critically ill patients require endotracheal intubation and are at high risk for hemodynamic collapse during this procedure. Prior studies suggest that there is up to a 25% risk of hemodynamic instability even in successful critical care unit intubations. Therefore, it is crucial to prevent peri-intubation hemodynamic instability to avoid poor patient outcomes through hemodynamic optimization prior to endotracheal intubation.

Point-of-care ultrasound has evolved as a simple, portable, and noninvasive tool for assessment of hemodynamic status. It can provide invaluable information about diagnoses and direct resuscitation in critically ill patients. This bedside imaging modality can help determine the etiology of shock, guide appropriate interventions prior to patient decompensation, and assess patient response to management changes. It can also assist in the evaluation of intravascular volume status and fluid responsiveness of critically ill patients.

Endotracheal intubation is especially perilous for a patient with right ventricular failure. Performing this procedure in patients with right ventricular failure can result in catastrophic hemodynamic collapse since the right heart is very sensitive to increases in afterload. Right ventricular failure resulting in hemodynamic collapse is an underappreciated complication of patients undergoing intubation and invasive mechanical ventilation.

Echocardiography during the preparation period of intubation allows for direct and noninvasive visualization of the right ventricle at the bedside and can play a major role in the stabilization of critically ill patients. Pre-intubation echocardiography can prevent hemodynamic deterioration by identifying a failing right ventricle, which is extremely sensitive and unable to compensate for any increase in afterload or decrease in preload from endotracheal intubation. Pre-intubation echocardiography can detect signs of a deteriorating right ventricle (pressure and volume overload) such as right ventricle dilation, bowing of the interventricular septum into the left ventricle, decrease in the size of the left ventricular cavity, and decreased left ventricular filling leading to decreased cardiac output (Figures 1–4). If acute right ventricular failure is identified prior to endotracheal intubation, it can help the physician select appropriate management strategies prior to intubation and avoid hemodynamic instability.

Figure 1. D-sign. Interventricular septum is flattened during diastole and forms D-shaped left ventricle.
Figure 2. Four-chamber apical view demonstrating enlarged right ventricle.
Figure 3. Parasternal long-axis view demonstrating dilated right ventricle.
Figure 4. Parasternal short-axis view showing decrease in the size of left ventricular cavity.

 

With pre-intubation detection of right ventricular failure, different strategies can be implemented prior to endotracheal intubation to avoid hemodynamic collapse. Non-invasive positive pressure ventilation can be an alternative in some cases, which has a less pronounced effect on venous return and preload compared to invasive mechanical ventilation. In the setting of pulmonary embolism (or pulmonary arterial hypertension), inhaled nitric oxide can be used to decrease pulmonary artery pressure through pulmonary vascular dilation. Other strategies to avoid worsening right ventricular failure include administration of vasopressors prior to endotracheal intubation and avoiding intravenous fluid boluses.

Pre-intubation echocardiography is a crucial step in the protocol during endotracheal intubation of critically ill patients to prevent poor patient outcomes. It allows clinicians to approach endotracheal intubation-associated hemodynamic instability in a specific, targeted manner. Integration of pre-intubation echocardiography can vastly improve the management and safety of critically ill patients, in hopes of decreasing the risk of poor outcomes.

 

Srikar Adhikari, MD, MS, FAIUM, is a professor in the Department of Emergency Medicine at the University of Arizona Medical Center.

Interested in learning more about POCUS? Check out the following posts from the Scan:

 

Ultrasound in Central Vein Assessment – The Importance of Knowing

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Thorough vascular assessment prior to any intravascular device insertion is of paramount importance – for both clinician and patient. It guides the clinician to evaluate the current state of vessel health, determining suitability of the veins, and to follow a pre-determined pathway that will lead to the best decision for the patient. The assessment phase alone in vascular access procedures highlights a number of important underlying anatomical structures, as there are frequently variances amongst many patient groups and it provides a platform to perform a thorough assessment of the vascular structures to evaluate vessel health, viability, size, and patency, including the location of other important and best-avoided anatomical structures – prior to performing any procedures. The success in complication-reduction alone drives the importance of patient safety and improved patient- and device-related outcomes, not to mention patient satisfaction and comfort.

Its use for assisting the proceduralist are many:

  • pre-procedural ultrasound assessment of the vascular anatomy provides a rational choice of the venous access most likely to be associated with an optimal clinical outcome;
  • real-time, ultrasound-guided puncture and cannulation of the vein reduces the risk of failure and/or damage to the surrounding structures;
  • ultrasound scan after the venipuncture allows an early/immediate detection of puncture-related complications such as pneumothorax or local hematoma;
  • ultrasound-based tip navigation verifies the proper direction of the guidewire and/or the catheter during its progression into the vasculature;
  • transthoracic echocardiography allows proper ultrasound-based tip location;
  • ultrasound is also useful for detection of late complications such as catheter-related venous thrombosis, tip migration, or fibroblastic sleeve.

A simple yet systematic approach to vessel assessment is the RaCeVA (Rapid Central Vein Assessment), a process manifested as a quick and highly effective process for performing vessel assessment in a compelling and methodical approach. It allows a systematic approach to exclude venous abnormalities such as thrombosis, stenosis, external compression, and anatomical variations of size and shapes; it also allows a full anatomic evaluation for optimum site selection and the best insertion approach for the patient. It also has many advantages: it takes only 30–40 seconds for each side, it is easy to teach, easy to learn, and it is a useful guide for a rational choice of the central vein to be accessed, in terms of patient safety and cost-effectiveness, since it helps the operator to choose the most favorable puncture site and the optimal insertion site, with an overall improvement of the clinical outcomes and patient satisfaction.

RaCeVA - table

The RaCeVA Steps

Important considerations include the following:

  1. size of the vein (internal diameter/caliber)
  2. depth of the vein (depth of target vessel from skin surface)
  3. respiratory variations (influence of respiratory cycle on vein diameter)
  4. compression by artery (influence of arterial pulsation on vein diameter)
  5. proximity to non-venous structures that must not be damaged (pleura, nerve, artery)
  6. exit site location – convenience/appropriateness in terms for best care and maintenance

Image 1

Overview of RaCeVA steps highlighting ultrasound transducer scanning points – courtesy of the author.

Utilization of the RaCeVA protocol throughout both pre- and post- device insertion stages offers multiple advantages: “before” (to define the anatomy and the best target vessel), “during” (with real-time techniques of ultrasound-guided venipuncture: short-axis in-plane, short-axis out-of-plane, long-axis in-plane), and “after” cannulation (to detect or rule out complications such as pneumothorax, malpositions, local hematoma).

 

As a tool, RaCeVA is designed (a) to teach the different ultrasound-guided approaches to the central veins, (b) to help the operator to scan systematically all possible venous options, and (c) to guide the operator in choosing the most appropriate vein to be accessed, on a rational and well-informed basis. Optimal training is mandatory, through formal programs and hands-on sessions that imply using vascular simulation phantoms – the latter being especially important for practitioners to perform repeated ultrasound-guided vascular cannulations without posing serious risks for patients and ultimately successfully transferring this practice to patients.

 

 

Comment below, or, AIUM members, continue the conversation on Connect, the AIUM’s online community to share your experience.

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Timothy R. Spencer, RN, DipAppSc, BHSc, ICCert, APRN, VA-BC™, is Director of Global Vascular Access, LLC, in Scottsdale, Arizona.

 

The Best of the Scan, 5 Years in the Making

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The Scan has been a home for all things ultrasound, from accreditation to zoos, since its debut 5 years ago, on February 6, 2015.MISC_SCAN_5_YR_ANN_DIGITAL_ASSETS_FB

In its first 5 years, the Scan has seen exponential growth, in large part due to the hard work of our 110 writers, who have volunteered their time to provide the 134 posts that are available on this anniversary. And it all began with Why Not Start? by Peter Magnuson, the AIUM’s Director of Communications and Member Services, who spearheaded the blog’s development.

In honor of this 5th Anniversary, here are some of your favorites:

Top 5 Most Viewed Posts

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1. Ultrasound Can Catch What NIPT Misses
by Simcha Yagel
(August 4, 2015)

Sonographer Stretches2. Sonographer Stretches for an ‘A’ Game
by Doug Wuebben and Mark Roozen
(January 31, 2017)

Keepsake3. The Issue with Keepsake Ultrasounds
by Peter Magnuson
(April 30, 2015)

Hip Flexor Stretch4. 3 Stretches All Sonographers Should Do
by Doug Wuebben and Mark Roozen
(January 19, 2016)

Anton5. From Sonographer to Ultrasound Practitioner: My Career Journey
by Tracy Anton
(October 23, 2018)

The Fastest Growing Posts
That Are Not Already in the Top 5

And we have plenty more great posts, such as:

A Personal Vignette From the ’60s and ’70s
Menstrual Pain: Is it Adenomyosis?
The Buzz in Orlando
Why SonoStuff.com
Vascular Access for Fiona
Therapy Dogs
Ultrasound at the Zoo
How Portable Ultrasound Got Me a Bottle of Wine
Why Teach Ultrasound?

Ultrasound-Guided Cancer Imaging: The Future of Targeted Cancer Treatment

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Tumor margins and malignant grade are best defined by vascular imaging modalities such as Doppler flow or contrast enhancement combined with videomicroscopy. The following are image-guided treatment options that can be performed on breast, prostate, liver, and skin cancers.

NEW DOPPLER APPLICATIONS

Blood vessel mapping using the various Doppler modalities is routinely used in both cancer treatment and reconstructive planning. In cancer surgery, it is critical to locate aberrant veins or arterial feeders in the operative site so postoperative blood loss is minimized. Advanced 3D Doppler systems allow for histogram vessel density measurement of neoplastic angiogenesis.

VESSEL DENSITY INDEX

(Fig 1) Baseline neovascularity is a treatment surrogate endpoint and therapy is maintained, increased, or suspended based on quantitative angiogenesis data.

SOLID ORGAN CANCER IMAGING UPDATES

Breast cancer, invading the lower dermis and nipple, discovered with high-resolution probes signifies the tumor has outflanked clinical observation essential for detecting the newly discovered entity of breast implant-associated anaplastic large cell lymphoma (BIA-ALCL). This capability is also vital for diagnosing the recent epidemic of male breast cancers arising near the mammographically difficult nipple areolar complex, occurring in our 911 First Responders.

For prostate cancer, 4D ultrasound can identify low-grade cancer delimited by the capsule and with low vessel density, and should be followed serially at 6-month intervals.

CONTRAST-ENHANCED ULTRASOUND (CEUS)

In 1990, Dr. Rodolfo Campani developed ultrasound contrast for liver imaging and Drs. Cosgrove (London) and Lassau (Paris) extended the use to breast, skin, and prostate tumors. CEUS is currently used worldwide but is not Food and Drug Administration (FDA)-approved in the United States.

One use for CEUS is microbubble neovascularity, which demonstrates therapeutic response since the Response Evaluation Criteria in Solid Tumors (RECIST) studies noted tumor enlargement during treatment might be related to cell death with cystic degeneration or immune cell infiltration destroying malignant tissue. Doppler ultrasound or CEUS reliably verifies decreased angiogenesis in place of contrast CT or dynamic contrast-enhanced (DCE) MRI. If vascular perfusion ceases, thermal treatments, such as cryotherapy, high-intensity focused ultrasound (HIFU), or laser ablation, should be completed.

Four-dimensional (4D) ultrasound imaging is real-time evaluation of a 3D volume so we can show the patient immediately the depth and the probability of recurrence. Specific echoes in skin cancer generated by nests of keratin are strong indicators of aggression and analyzed volumetrically. Highly suspect areas are checked for locoregional spread and a search is performed for lymphadenopathy so we can determine if the disease is confined and whether further surgical intervention is unlikely at this time. Patients are reassured because they simultaneously see the exam proceed in systematic stages. In serious cases, the patient is forewarned that the operation involves skin grafts and tissue construction.  4D ultrasound permits image-guided biopsy of the most virulent area of the dermal tumor and allows the pathologist to focus on the most suspicious region of the lymph node mass excised from the armpit, neck, or groin. Some laboratories are using postop radiography and sonography for better specimen analysis.

VIDEO DIGITAL MICROSCOPY VS BIOPSY

Fear of complications can deter patients from seeking medical opinion and surgical intervention, so many opt for noninvasive options. Imaging can help to reduce unnecessary biopsies because it can help identify the 1 out of every 33,000 moles that is malignant, while weeding out those that are not.

Once skin cancer is diagnosed, the treatment depends on depth penetration, possibly involving facial nerves, muscles around the eye and nasal bone or ear cartilage. Verified superficial tumors are treated topically or by low dose non-scarring radiation. Many cancers provoke a benign local immune response or coexistent inflammatory reaction that simulates a much larger area of malignancy, and cicatrix accompanies the healing response. 4D imaging combined with optical microscopy (RCM (reflectance confocal microscopy) or OCT (optical coherence tomography)) defines the true border during surgery, sparing healthy tissue, resulting in smaller excisional margins and less scar formation.

 

Do you have any tips on incorporating ultrasound in cancer imaging? Comment below, or, AIUM members, continue the conversation on Connect, the AIUM’s online community.

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Robert Bard, MD, DABR, FASLMS, currently runs a private consulting practice in New York City. He authored Image Guided Dermatologic Treatments, Image Guided Prostate Cancer Treatment, and DCE-MRI of Prostate Cancer and is a member of multiple leading international imaging societies. Since 1972, Dr. Bard has pioneered digital imaging technologies as alternatives to surgical biopsies for dermatologic and solid organ neoplastic disease.