Juan A. Marmol-Velez

University of Texas Health Science Center at San Antonio, San Antonio, Texas, United States

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Publications (8)7.35 Total impact

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    ABSTRACT: Implantable cardioverter defibrillators (ICDs) monitor intracardiac electrocardiograms (EGM) to discriminate between ventricular and supraventricular tachycardias. The incidence of inappropriate shocks remains high due to misclassification of the tachycardia in an otherwise hemodynamically stable individual. Coupling EGMs with an assessment of left ventricular (LV) stroke volume (SV) could help in gauging hemodynamics during an arrhythmia and reducing inappropriate shocks.
    Heart rhythm: the official journal of the Heart Rhythm Society 06/2014; · 4.56 Impact Factor
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    ABSTRACT: Background Implantable cardioverter defibrillators (ICDs) monitor intracardiac electrocardiograms (EGM) to discriminate between ventricular and supraventricular tachycardias. The incidence of inappropriate shocks remains high due to misclassification of the tachycardia in an otherwise hemodynamically stable individual. Coupling EGMs with an assessment of left ventricular (LV) stroke volume (SV) could help in gauging hemodynamics during an arrhythmia and reducing inappropriate shocks. Objective Use admittance method to accurately derive LV SV. Methods Ultrasonic flow-probe and LV endocardial crystals were used (canines n=12) as the standard for LV SV. Biventricular pacing leads were inserted to obtain admittance measurements. A tetrapolar, complex impedance measurement was made between the Bi-V leads. The real and imaginary components of impedance were used to discard the myocardial from the blood component to derive instantaneous blood conductance (Gb). Alterations in SV were measured during RV pacing, dopamine infusion, and inferior vena cava occlusion (IVCO). Results Gb tracks steady state changes in SV more accurately than traditional magnitude (i.e. |Y|, without removal of the muscle signal) during RV pacing and dopamine infusion (p = 0.004). Instantaneous LV volume was also tracked more accurately by Gb than |Y| in the subset of subjects that underwent IVCOs (n=5, p=0.025). Finite element modeling demonstrates that admittance shifts more sensitivity of the measurement to the LV blood chamber as the mechanism for improvement (see appendix). Conclusion Monitoring LV SV is possible using the admittance method with biventricular pacing leads. The technique could be piggybacked to compliment EGMs to determine if arrhythmias are hemodynamically unstable.
    Heart Rhythm. 01/2014;
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    ABSTRACT: In the United States, trauma is the leading cause of death among those who are 1-44 years old, with cardiovascular injuries representing the second most common cause of traumatic death after central nervous system injuries. Evaluation of trauma patients with suspected cardiac injury may be complex and include electrocardiography, measurement of cardiac biomarkers, and imaging examinations. Contrast material-enhanced computed tomography (CT) has become one of the most valuable imaging tools available for evaluating hemodynamically stable patients with suspected cardiac injury. The presence of hemopericardium, with or without cardiac tamponade, is one of the most significant findings of cardiac injury. Other complications that result from blunt cardiac injury, such as pericardial rupture and cardiac herniation, may be readily depicted at multidetector CT. Assessment of patients with cardiac injuries, particularly those with penetrating injuries, is a challenging and time-critical matter, with clinical and imaging findings having complementary roles in the formation of an accurate diagnosis. Patients who are hemodynamically stable, particularly those with penetrating cardiac injuries, also may benefit from a timely imaging examination. In addition to chest radiography, other available modalities such as transthoracic and transesophageal echocardiography, nuclear medicine, and magnetic resonance imaging may play a role in selected cases.
    Radiographics 05/2012; 32(3):633-49. · 2.79 Impact Factor
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    ABSTRACT: PURPOSE/AIM 1. Review imaging findings of chronic myocardial infarctions (MI) in standard contrast-enhanced chest CT, CCTA, and MRI. 2. Discuss the associated, chronic complications of MI and their imaging manifestations. 3. Learn about salient points to be analyzed by the radiologist that impact intervention planning, clinical management, and follow-up. CONTENT ORGANIZATION 1. Cardiac anatomy and arterial territories. 2. Illustrative cases of chronic anatomical and functional complications of myocardial infarction including delayed enhancement, scarring, fatty infiltration, calcifications, aneurysms, thrombus formation, dyskinesia or akinesia, dilated cardiomyopathy, and dysrrhythmias. 3. Traumatic myocardial injury leading to infarction and chronic changes. 4. Review of the complications associated with chronic MI and prognosis. SUMMARY The major learning points of this exhibit are to (i) learn to appreciate subtle and clear signs of prior MI by standard chest CT, CCTA, and MR imaging; (ii) understand the associated chronic complications and their impact in cardiovascular function; and, (iii) understand the utility and limitations of the commonly used cross-sectional imaging modalities.
    Radiological Society of North America 2008 Scientific Assembly and Annual Meeting; 12/2008
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    ABSTRACT: PURPOSE/AIM 1. To briefly review the anatomy and embryology of the thoracic aorta. 2. Discuss the most appropriate techniques to image the aortic arch and their pitfalls. 3. Describe several cases illustrating diverse aortic arch pathology encountered in patients with or without prior surgical instrumentation. CONTENT ORGANIZATION A. Embryology and anatomy of the aortic arch B. Imaging techniques for aortic disease: 1. Transesophageal echocardiography. 2. Conventional aortogram. 3. CT angiography. 4. MR Angiography. 5. Pitfalls and artifacts in aortic disease. C. Etiology of aortic arch aneurysms: 1. Congenital Sinus of Valsalva aneurysm. 2. Acquired Sinus of valsalva aneurysm. 3. Ascending aortic aneurysm. 4. Aneurysms of the arch. 5. Stanford Type A aortic dissection 6. Traumatic aortic injury. SUMMARY The thoracic aorta can be affected by a myriad of pathologies leading to dissection or aneurysm formation that are uniformly associated with high morbidity, mortality and medical costs. There are several available imaging techniques each with particular limitations of their own. Cross sectional imaging by means of CT or MRI can provide precise aneurysm measurements, determine the extension and nature of the process as well as evaluate cardiac and coronary anatomy and function.
    Radiological Society of North America 2007 Scientific Assembly and Annual Meeting;
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    ABSTRACT: PURPOSE/AIM 1. Review the most common types of cardiac pacing devices (pacemakers and automatic implantable cardiac defibrillators) and typical indications for their use. 2. Illustrate the positioning of their components (generator, leads, electrodes). 3. Discuss the associated complications and the role of different imaging modalities in their evaluation. CONTENT ORGANIZATION 1. Basics fundamentals of cardiac arrhythmias. 2. Pacing devices. 3. Indications for placement. 4. Most common types of devices used. 5. Review of imaging findings: Anatomic variations Anatomic approach Complications SUMMARY With the increase of life expectancy and escalating incidence of cardiovascular disease there has been a dramatic increase in the number of patients meeting clinical criteria and subsequently undergoing placement of cardiac pacing systems and implantable cardiac defibrillators (ICD’s). It is of outmost importance for the radiologist to recognize not only the type of device used, but also the potential anatomic variations and associated complications.
    Radiological Society of North America 2009 Scientific Assembly and Annual Meeting;
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    ABSTRACT: PURPOSE/AIM 1. Developmental anatomy of the sinus of Valsalva. 2. Revisit the typical insidious nature of aneurysms of the sinus of Valsalva and when to suspect their presense. 3. Signs and symptoms of acutely presenting aneurysms of the sinus of Valsalva, which are usually due to rupture. 4. Non-aneurysmal pathology affecting the sinuses of Valsalva. CONTENT ORGANIZATION 1. Embryology and anatomy of the sinuses of Valsalva. 2. Epidemiology and prevalence of congenital and acquired aneurysms of the sinus of Valsalva. 3. MDCT and echocardiography illustrative cases of insidious and acutely presenting aneurysms of the sinus of Valsalva. Non-aneurysm pathology cases including complications of post valvular or aortic root repair and trauma. 4. Aneurysm rupture complications including left to right shunts, fistulas, and sudden aortic regurgitation. SUMMARY The major learning points of this exhibit are to: (i) learn to identify and diagnosed the spectrum of acquired and congenital aneurysms of the sinus of Valsalva based on the MDCT imaging findings; (ii) clinical presentation and associated complications; (iii) non-aneurysmal pathology affecting the sinuses of Valsalva; and, (iv) to understand the advantages and disadvantages of MDCT over other imaging modalities.
    Radiological Society of North America 2008 Scientific Assembly and Annual Meeting;
  • Juan A. Marmol-Velez, Carlos S. Restrepo, Daniel Vargas, Terry Bauch
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    ABSTRACT: PURPOSE/AIM 1. To review the techniques used for acquisition and reconstruction of cardiac CTA data employed on functional analysis 2. To understand the post-processing and workflow used in a routine examination. 3. To interpret these data in the light of other techniques. 4. To describe the strengths and limitations of functional cardiac imaging by MDCT. CONTENT ORGANIZATION The exhibit will be an interactive presentation. Clinical cases will be used to highlight: A. Acquisition techniques, pitfalls and troubleshooting B. Reformatting and post-processing of data C. Examination workflow D. Cardiac chamber measurement E. Estimation of ventricular mass F. Measurement of ejection fraction G. Correlations of MDCT data with echocardiography, MRI, nuclear medicine and cine-ventriculography H. Case presentations I. Future developments in functional cardiac imaging SUMMARY Data collected in cardiac CTA extends beyond coronary angiography. Image post-processing yields information such as ejection fraction, and regional wall motion and thickness. These values correlate with those of other well-established cardiac imaging techniques. Physicians involved with cardiac CT should be familiar with the software tools used and the standards of chamber quantification, to be able to incorporate clinically valuable information on cardiac function in their workflow.
    Radiological Society of North America 2007 Scientific Assembly and Annual Meeting;