Innovations in 3-D and 4-D Technology in the Cath Lab

There have been tremendous advances in 3-dimensional (3-D) technologies in the past few years, not only in various medical and surgical fields but also in our daily lives outside of work; with more and more new features in cell phones, computer design programs, and movies!!  4-dimensional (4-D) imaging captures 3-D images over time. These technologies are particularly important in cardiology, especially in interventional cardiology. The heart is a very dynamic organ, and understanding the variation in the anatomy of vessels and geometry of cardiac structures is key to ensuring successful procedures, patient’s safety and good outcomes. More recently, newer innovations in both 3-D and 4-D technologies have been developed, so I decided to shed light on some of these innovations and how they can be potential game-changers in the cath lab.

  • 3-D Holograms

This technology was actually displayed at the Transcatheter Cardiovascular Therapeutics (TCT) 2019 meeting. It converts live transesophageal echo (TEE) imaging into real-time 3-D holographic video in the cath lab to aid structural heart procedures.  The 3-D hologram is projected on a special display screen, and the interventional cardiologist uses hand movements and a foot pedal/switch to change the image orientation without breaking the sterile field. It also allows the operator to see the tools they use in the cath lab, including catheters or devices, in real-time in a 3-D format. This technology does not even require the user to wear 3-D glasses! It was submitted for FDA regulatory review in September 2019.

  • HeartFlow Planner

This is a noninvasive, real-time virtual tool for coronary artery disease intervention. It allows interventional cardiologists to virtually map vessels on a 3-D coronary tree, with color codes indicating the fractional flow reserve-computed tomography (FFR-CT) values for each vessel as measured by a computational fluid dynamics algorithm. This seems to be a good tool for percutaneous coronary intervention (PCI) planning in vessels with significant disease; as it aims to provide us with a non-invasive way to determine whether a stenotic lesion if potentially flow limiting. However, it is important to note the CT-FFR has its own limitations, and some patients might still need invasive FFR for accurate assessment. This tool was approved by the FDA in September 2019.

Figure 1: 3-D CT-FFR coronary tree showing both flow limiting and non-flow limiting lesions [from reference 1].

  • 3-D Printing

3-D printing has been used in the surgical fields for more than a decade. It refers to making complex 3-D objects from computer-aided designs. This technology has been increasingly utilized in structural heart procedures in the past few years, where these 3-D models can be printed from a patient’s CT, magnetic resonance imaging (MRI), or 3-D ultrasound images (Figure 1). These 3-D printed structures not only help with procedural planning and device sizing but also allow operators to practice dry runs and perform pre-procedural navigation.

Figure 2: Image of a 3-D printed model which shows cardiac valves and major vessels with their geometric locations relative to each other (reference 3).

  • 4-D Imaging

4-D imaging adds an important component to 3-D imaging, which is the change of these 3-D images over time. 4-D flow images include the direction of blood flow, blood velocities and shear wall stress [2] (Figure 3). This is particularly important in coronary interventions, structural heart procedures and different congenital abnormalities where identification of blood flow in the 4-D view is useful, especially when the anatomy is complex. These changes in position over time help guide our procedures, not only to ensure successful outcomes but also to avoid potential complications. These 4-D images require large amounts of data, but they can be obtained from either cardiac MRI or computational fluid dynamics, which is a specialized area of mathematics and fluid mechanics in engineering [2]. 4-D imaging is still in its early phases, but it is another exciting advancement in our field.

Figure 3: Representation of an MRI-generated 4-D flow image showing blood flow through the aorta and major vessels (reference 4).

In conclusion, we have seen and continue to see tremendous advances in the innovations of 3-D and 4-D imaging with important implications in our work in the cath lab. With our continued collaboration with informational technology experts, engineers, and scientists, these innovations are potentially game-changers in different fields, including coronary interventions and structural heart procedures. I look forward to seeing how this technology continues to evolve in the coming decades!!


  • Fornell, Dave “Overview of the top news and new technologies at the 2019 Transcatheter Cardiovascular Therapeutics meeting”, November 2019,



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Sometimes Less is More

A 64-year-old male presented to emergency room (ER), with complaints of shortness of breath for one day. He had a past medical history of hypertension, end stage renal disease on hemodialysis (HD), and grade I obesity. He reported that he missed his last HD session, which was two days prior to presentation. He denied any chest pain, palpitations, cough, or fever. Patient further mentioned that he was able to walk >10 blocks without any chest pain or shortness of breath until a couple days ago. In the ER, examining physician documented presence of a systolic ejection murmur heard best at the second right intercostal space and bilateral rales, 1+ pedal edema; jugular venous distention of 4cm. Urgent transthoracic echocardiogram (TTE) was ordered by ER physician to further investigate the aortic stenosis (AS) murmur. TTE showed aortic valve area 0.98cm2, mean gradient 32mmHg, aortic jet velocity 3.5m/s; mild left ventricle (LV) concentric hypertrophy with grade 1 diastolic dysfunction, and LV ejection fraction of 60-65%. Subsequently, patient was admitted to cardiac telemetry and primary team consulted renal and cardiothoracic (CT) team for HD and for aortic valve replacement (AVR), respectively.

CT surgery team requested cardiology consult as a part of pre-operative assessment for possible surgical AVR. Physical examination by the attending cardiologist was remarkable for II/VI mid-systolic peaking crescendo-decrescendo murmur with normal carotid pulse upstrokes. Cardiac catheterization was recommended for further evaluation as there was discrepancy between the findings on noninvasive testing and physical examination regarding severity of the AS. Cardiac catheterization revealed non obstructive coronary artery disease (30% stenosis of mid RCA) and moderate AS (aortic valve area 1.38cm2, mean gradient 28mmHg, aortic jet velocity 3.3m/s). During recovery period patient developed hematoma at access site (right groin), which was managed conservatively but resulted in prolongation of his hospital stay by 48 hours. In the meantime, the patient underwent hemodialysis and had symptomatic relief in his dyspnea. He was discharged home to follow up with his outpatient hemodialysis center.



This gentleman presented to ER with complain of shortness of breath after missing a HD session. Although, not incorrect, the systolic murmur heard by ED physician led to a cascade of downstream testing. In fact, the ‘benign’ ‘non-invasive’ testing ordered as a part of comprehensive work-up led to a delay for patient getting the HD session. Physical examination is an essential part of accurate assessment of a patient’s disease process. However, our daily practice has been increasingly occupied by ‘tunneled vision’ of things.

Aortic stenosis (AS) is one of the most common valvular diseases associated with systolic murmur in the elderly population1. An essential part of physical exam of AS is assessing the severity. Munt et al, found significant correlation of physical exam findings like grade of murmur and timing of murmur peak with severity of AS2. Further, delay in carotid upstroke and decreased amplitude was well associated with increasing grade of AS severity as measured by aortic valve area (AVA). Although, one may argue that physical exam is limited by observer expertise and inter-observed variability3, echocardiographic parameters have their own pitfalls. The AVA measurement depends on accurate evaluation of LVOT diameter, which has a variability rate of 5-8% thus providing a significant potential for error4. Further, co-existing LV dysfunction or valvular jets (e.g. MR, AR) can interfere with precise interpretation of echocardiographic parameters.

In summary, the patient should have received urgent HD on presentation. The work up for systolic murmur would have been more appropriate on an outpatient basis. This particular scenario also brings into picture the rising health care costs in the United States, contributed by both additional testing and prolonged hospitalizations. Overall, it is worth concluding that careful physical examination and assessment of the patient is foremost to efficient and ‘do not harm’ philosophy of medicine.



1) Osnabrugge R, Mylotte D, Head SJ, Van Mieghem NM, et al. Aortic Stenosis in the Elderly Disease Prevalence and Number of Candidates for Transcatheter Aortic Valve Replacement: A Meta-Analysis and Modeling Study. J Am Coll Cardiol. 2013;62(11):1002-1012.

2) Munt B, Legget ME, Kraft CD, Miyake-Hull CY, et al. Physical examination in valvular aortic stenosis: Correlation with stenosis severity and prediction of clinical outcome. Am Heart J 1999;137:298-306.

3) Stout KK, Otto CM. Quantification of Valvular Aortic Stenosis. ACC current journal review Mar/Apr 2003.

4) Baumgartner H, Hung J, Bermejo J, Chambers JB, et al. Echocardiographic assessment of valve stenosis: EAE/ASE recommendations for clinical practice.