This material is the result of work supported with resources and the use of the facilities at the Clement J. Zablocki Veterans Affairs Medical Center in Milwaukee, Wisconsin.

The Institutional Review Board of the Clement J. Zablocki Veterans Affairs Medical Center approved the protocols. Written informed consent was waived because invasive cardiac monitoring and TEE are routinely used in all patients undergoing cardiac surgery in our institution. Patients with relative or absolute contraindications for TEE, those undergoing repeat median sternotomy or emergency surgery, and those with atrial or ventricular tachyarrhythmias were excluded from participation.
1. Anesthesia
<ol>
	<li>Provide each patient with intravenous midazolam (1 to 3 mg) and fentanyl (50 to 150 &#181;g) for conscious sedation before surgery.</li>
	<li>Use local anesthesia (subcutaneous 1% lidocaine) for insertion of intravenous and radial artery catheters. Test the quality of the local anesthesia with a pinprick.</li>
	<li>Ensure that the patient receives supplemental oxygen using a nasal cannula (2 to 4 L/min).</li>
	<li>Place a central venous or pulmonary artery catheter using local anesthesia (subcutaneous 1% lidocaine) under sterile conditions through the right or left internal jugular vein with ultrasound guidance based on appropriate clinical indications.</li>
	<li>Induce anesthesia using intravenous fentanyl (5 mcg/kg), propofol (1 to 2 mg/kg), and rocuronium (0.1 mg/kg). Maintain anesthesia using inhaled isoflurane (end-tidal concentration of 1%) in an air-oxygen mixture, fentanyl (1 to 2 &#181;g/kg/h), and rocuronium (0.05 mg/kg) titrated to effect using neuromuscular monitoring.</li>
	<li>Suction the stomach using an oral-gastric tube.</li>
	<li>Place ultrasound jelly in the patient&#8217;s hypopharynx. Lift the jaw anteriorly and advance a TEE probe into the esophagus with gentle pressure to overcome resistance of the hypopharygeus muscle.</li>
</ol>
2. Transesophageal Echocardiography
<ol>
	<li>Perform a comprehensive TEE examination following American Society of Echocardiography/Society of Cardiovascular Anesthesiologists guidelines42 in each patient.</li>
	<li>Place a pulse-wave Doppler sample volume between the tips of the mitral leaflets to record trans-mitral blood flow velocity in the mid-esophageal four-chamber TEE imaging plane (Figure 1).</li>
	<li>Identify the early LV filling and atrial systole blood flow waveforms of trans-mitral blood flow velocity, and measure their corresponding peak velocities and velocity-time integrals (VTIE and VTIA, respectively) using the echocardiography equipment&#8217;s integrated software package (Figure 1).</li>
	<li>Calculate the atrial filling fraction (&#946;) as the ratio of atrial to total LV filling: 
	<img alt="Equation 1" src="/files/ftp_upload/58374/58374eq1.jpg" /></li>
	<li>Measure the maximum diameter of the LV outflow tract immediately below the aortic valve in the mid-esophageal aortic valve long axis TEE view during mid-systole (Figure 2A).</li>
	<li>Calculate the area of the LV outflow tract assuming circular geometry as the product of &#960;/4 and the square of the diameter (see step 2.5 above).</li>
	<li>Obtain a deep transgastric long axis TEE view, and place a pulse-wave Doppler sample volume in the distal LV outflow tract to record a blood flow velocity envelope (Figure 2B) at the same level where the diameter was measured (see step 2.5 above); integrate the area of this waveform using the echocardiography equipment&#8217;s software package to obtain VTI.</li>
	<li>Multiply the resulting velocity-time integral (VTI) of the LV outflow track blood flow velocity waveform (Figure 2B) by the area of the outflow track (see step 2.6) to obtain stroke volume (SV).</li>
	<li>Record video clips of the mid-esophageal bicommissural and LV long axis TEE imaging planes, respectively42. Be sure to include several cardiac cycles in each recording.</li>
	<li>Visually inspect slow-motion images of the video clips (see step 2.9 above) after the ECG T-wave to choose the maximum opening of the mitral valve leaflets.</li>
	<li>Measure the distance between the mitral leaflets (Figures 3A and 3B) using the echocardiography equipment&#8217;s &#8220;caliper&#8221; function.</li>
	<li>Calculate the mitral valve diameter (D) as the average of the major (transcommissural anterior-lateral-posterior-medial) and minor (anterior-posterior) lengths.</li>
	<li>Calculate VFT using the formula: 
	<img alt="Equation 2" src="/files/ftp_upload/58374/58374eq2.jpg" /></li>
	<li>Perform all quantitative echocardiographic measurements in triplicate at end-expiration.</li>
</ol>
3. Experimental Design
<ol>
	<li>Determine VFT, indices of LV diastolic function, and hemodynamics during steady-state conditions 30 minutes before and 15, 30, and 60 minutes after cardiopulmonary bypass (CPB) in 10 patients with normal preoperative LV ejection fraction under coronary artery surgery to test the hypothesis that CPB transiently decreases VFT39.</li>
	<li>Test the hypothesis that LV pressure-overload hypertrophy produced by aortic valve stenosis reduces VFT by examining (in one group of 8 patients undergoing aortic valve replacement) for severe aortic stenosis and comparing observations to another group of 8 patients with normal LV wall thickness undergoing coronary artery surgery40. Measure VFT, LV diastolic function, hemodynamics, and end-diastolic posterior wall thickness during steady-state conditions 30 minutes before CPB.</li>
	<li>Test the hypothesis that abnormal diastolic blood flow entering the LV affects trans-mitral LV filling efficiency in 8 patients with aortic valve stenosis and moderate aortic insufficiency versus 8 patients with aortic stenosis who do not have regurgitant valves38. Measure VFT and other parameters as described above (step 3.2).</li>
	<li>Test the hypothesis that advanced age is associated with a reduction in LV filling efficiency quantified using VFT in 7 octogenarians (82 &#177; 2 years) compared to 7 younger patients (55 &#177; 6 years)41 undergoing coronary artery surgery. Ensure that both groups have normal preoperative LV ejection fraction. Measure VFT and other parameters as described above (step 3.2).</li>
</ol>
4. Statistics
<ol>
	<li>Present the data as mean &#177; standard deviation.</li>
	<li>Evaluate data using analysis of variance (ANOVA) followed by Bonferroni&#8217;s modification of Student&#8217;s t-test.</li>
	<li>Use linear regression analysis to determine the relationships between VFT and end-diastolic posterior wall thickness and between VFT and age.</li>
	<li>Reject the null hypothesis when p &#60; 0.05.</li>
</ol>

The authors have no competing financial interests or other conflicts of interest pursuant to this work.

The current results illustrate that VFT can be reliably measured during cardiac surgery using the TEE techniques described here. Previous descriptions of VFT used transthoracic echocardiography in conscious subjects, but this approach cannot be utilized when the chest is open. We used intraoperative TEE to determine VFT in the anesthetized patients undergoing cardiac surgery during which changes in LV filling dynamics are often encountered as a result of ischemia-reperfusion injury or surgical interventions. Our findings indicate that VFT measurements reflect changes in LV filling efficiency produced by transient CPB-induced impaired relaxation pattern diastolic dysfunction, aortic valve disease, and aging. The current technique for calculating VFT during cardiac surgery requires high-quality TEE images and video clips during steady-state hemodynamic conditions to assure precise measurements of mitral valve and LV outflow tract dimension and blood flow (Figure 1, Figure 2, and Figure 3). Not all patients will have optimal imaging windows because of off-axis rotation of the heart or pathological changes in cardiac geometry. Despite these potential limitations, experienced intraoperative echocardiographers should be able to easily obtain the necessary mid-esophageal four-chamber, mid-esophageal bicommissural, mid-esophageal LV long axis, and deep transgastric long axis views during the comprehensive TEE examination42. The technique may also be unreliable when rapidly changing hemodynamic conditions are present. It does not provide direct visualization of blood flow movement within the LV associated with the vortex, as previously characterized using Doppler vector flow mapping6,20,21 or particle imaging velocimetry9,22,23,24. Accurate measurement of LV outflow track diameter using two-dimensional echocardiography is especially important because this variable is squared in the calculation of area and errors are magnified as a result. Similarly, accurate measurements of mitral valve minor and major axis length are essential because the cube of the average of these two dimensions appears in the denominator of the VFT formula. Two-dimensional echocardiography consistently underestimates aortic and mitral valve areas compared with three-dimensional reconstruction techniques43,44. The impact of these differences between two- and three-dimensional TEE on VFT is an area of current research by our group.
Additionally, isoflurane was used for maintenance of anesthesia in our studies. This volatile anesthetic is a vasodilating negative inotrope that reduces LV preload and afterload, decreases myocardial contractility, and affects LV diastolic function in a dose-related manner45,46. These cardiovascular changes may have influenced atrial filling fraction and stroke volume in our studies. Nevertheless, the values of VFT obtained in anesthetized patients with normal preoperative LV ejection fraction undergoing coronary artery surgery before CPB were similar to those described in healthy conscious subjects8. These data suggest that baseline anesthesia does not substantially alter LV filling efficiency, but we are currently examining this hypothesis. VFT has been previously shown to be an independent predictor of mortality in patients with congestive heart failure30, but it is unknown whether intraoperative changes in VFT are predictive of perioperative morbidity or mortality in cardiac surgery patients. This topic is also an area of interest that we are actively pursuing.
We first used this technique of noninvasively calculating VFT in a study examining the impact of CPB on VFT in isoflurane-fentanyl-anesthetized patients with normal preoperative LV ejection fraction undergoing coronary artery surgery39. LV diastolic dysfunction occurs after cardiopulmonary bypass as a result of global ischemia-reperfusion injury and a profound systemic inflammatory response47,48,49. This diastolic dysfunction eventually recovers within minutes to hours based on the efficacy of myocardial protection during and the duration of CPB50. Indeed, our findings confirmed that LV diastolic dysfunction occurs after CPB. This effect was accompanied by transient reductions in VFT that recovered within one hour after separation from CPB. The declines in VFT resulted from an increase in &#946; and a modest decrease in SV because mitral valve diameter was unchanged. The recoveries of VFT, &#946;, E/A, and SV after CPB were similar. Notably, VFT observed here did not fall below the normal range of VFT (3.3 to 5.5) in healthy individuals. Our patients had normal preoperative LV systolic and diastolic function, were exposed to relatively short CPB times (93 &#177; 27 min), and were treated with regular doses of antegrade and retrograde cardioplegia. These factors probably combined to reduce ischemia-reperfusion injury during aortic cross-clamp application39. CPB has also been shown to cause transient declines in trans-mitral blood flow propagation velocity (Vp) consistent with attenuated early LV filling in patients undergoing coronary artery surgery49 as a result of decreases in LV compliance51 and reductions in early diastolic intraventricular pressure gradients52. A relationship between vortex ring formation and Vp was previously demonstrated53, and our findings supported those of other investigators49 in similar patient populations.
We subsequently examined the effects of pressure-overload LV hypertrophy produced by severe calcific degenerative aortic valve stenosis in patients with preserved LV systolic function undergoing aortic valve replacement40. A second group of patients with normal LV wall thickness undergoing coronary artery surgery served as controls. Chronically elevated LV end-systolic wall stress causes LV pressure-overload hypertrophy as a compensatory response in the presence of aortic valve stenosis54. LV wall thickening without dilatation occurs as a consequence of an increase in the diameter of individual myocytes. This LV remodeling is associated with interstitial fibrosis55,56. Delays in apical recoil57,58 also occur that further attenuate early LV filling58,59, which causes LV diastolic dysfunction by delaying LV relaxation and reducing LV compliance55,60. Thus, VFT is reduced in the presence of delayed relaxation in patients with LV pressure-overload hypertrophy vs. those with normal LV wall thickness. Our findings were attributed to an increase in &#946; and decline in SV at similar filling pressures consistent with a decrease in LV compliance. A significant correlation between decreases in VFT and the severity of hypertrophy was shown using linear regression analysis. This observation suggests that the degree of pressure-overload hypertrophy is inversely related to LV filling efficiency quantified using vortex formation time.
Valvular insufficiency often occurs in conjunction with severe calcific degenerative aortic valve stenosis because prominent leaflet calcification prevents complete coaptation. We conducted another investigation to ascertain whether regurgitant blood flow into the LV through an incompetent aortic valve affects LV filling efficiency by interfering with trans-mitral blood flow38. We compared patients with severe aortic valve stenosis undergoing valve replacement who had moderate centrally-directed aortic insufficiency with a second group of patients who did not have regurgitation. We quantified aortic insufficiency using the regurgitant jet width LV outflow track diameter ratio measure with color Doppler M-mode echocardiography61. Our results showed that moderate aortic insufficiency increases VFT in patients with aortic valve stenosis. However, this increase in VFT does not suggest an improvement in LV filling efficiency has occurred because of abnormal regurgitant flow into the LV through the aortic valve. LV diastolic pressure rapidly increases in moderate to severe aortic insufficiency62, attenuating trans-mitral LV filling and reducing mitral valve area63,64,65. The results indicate that mitral valve diameter and area were reduced in patients with moderate aortic insufficiency versus those without regurgitation. These observations were most likely due to a decrease in minor axis length, resulting from attenuated anterior mitral leaflet opening caused by aortic regurgitant during LV filling, thereby, falsely elevated VFT. Indeed, VFT reported in our study (5.7 &#177; 1.7) was greater than the upper limit of normal VFT (5.5) in healthy conscious individuals8 and patients with normal LV geometry during anesthesia (4.3 &#177; 0.5)40. Therefore, it is highly likely that abnormal diastolic flow into the LV invalidates VFT as an index of LV filling efficiency.
We recently studied the influence of advanced age on VTF in elderly patients undergoing coronary artery surgery41. Progressive LV diastolic stiffening66, decreased intraventricular diastolic kinetic energy67, and attenuated diastolic suction68 cause LV diastolic function in the elderly69,70,71,72. Octogenarians with normal preoperative LV ejection were compared with a younger cohort of patients (&#8804; 62 years of age). We found that VFT was lower in octogenarians compared with younger patients. These observations were expected and occurred in conjunction with an impaired relaxation pattern of LV diastolic dysfunction and a modest reduction in SV at similar LV filling pressures. Mitral valve diameter was similar in octogenarians versus younger patients and did not contribute to the differences in VFT between groups. It is noteworthy that VFT was similar in octogenarians compared with patients with severe aortic valve stenosis that we previously reported38,40. Indeed, aortic stenosis is another condition characterized by impaired relaxation LV diastolic dysfunction and reductions in LV compliance. A significant inverse correlation between VFT and age was also demonstrated despite the small sample size (n = 7 per group; Figure 6). The decline in VFT that occurs with age that may eventually become indistinguishable from heart failure produced by pathological processes such as restrictive diastolic dysfunction19 or dilated cardiomyopathy8. Our results were consistent with reductions in early peak diastolic intraventricular kinetic energy in elderly subjects with depressed LV function67.
In summary, noninvasive measurement of VFT using standard two-dimensional and Doppler TEE is straightforward in anesthetized patients undergoing cardiac surgery. This technique may allow cardiac anesthesiologists and surgeons to assess the impact of pathological conditions and surgical interventions on LV filling efficiency in real time.

Fluid mechanics is a critical yet often underappreciated determinant of left ventricular (LV) filling. A three-dimensional rotational body of fluid, known as a vortex ring, is generated whenever a fluid traverses an orifice1,2,3. This vortex ring improves the efficiency of fluid transport compared with a continuous linear jet4. Movement of blood through the mitral valve during early LV filling causes a vortex ring to form5,6,7,8 and facilitates its propagation into the chamber by preserving fluid momentum and kinetic energy9. These actions enhance LV filling efficiency4,10,11,12,13. The ring not only inhibits blood flow stasis in the LV apex14,15,16,17 but also directs flow preferentially beneath the anterior mitral leaflet7,18, effects that decrease the risk of apical thrombus formation and facilitate filling of the LV outflow track19, respectively. Contrast echocardiography17, Doppler vector flow mapping6,20,21, magnetic resonance imaging7, and particle imaging velocimetry9,22,23,24 have been used to demonstrate the appearance and behavior of trans-mitral vortex rings under normal and pathological conditions. The left atrial-LV pressure gradient, the degree of diastolic mitral annular excursion, the minimum LV pressure achieved during diastole, and the rate and extent of LV relaxation are the four major determinants of the duration, size, flow intensity, and position of the trans-mitral ring2,12,25,26,27,28,29.
Vortex ring development is most often quantified with a dimensionless parameter (vortex formation time; VFT) based on fluid ejection from a rigid tube3, where VFT is defined as the product of the time-averaged fluid velocity and the duration of ejection divided by the orifice diameter. The optimal size of a vortex ring is achieved when VFT is 4 in vitro because trailing jets and energetic limitations prevent it from attaining a larger size3,4. Mitral valve VFT has been approximated clinically using transthoracic echocardiography8,30,31. Based on analysis of trans-mitral blood flow velocity and mitral valve diameter (D), it can be easily shown8 that VFT = 4 &#215; (1-&#946;) &#215; EF &#215;&#945;3, where &#946; = atrial filling fraction, EF = LV ejection fraction, and &#945; = EDV1/3/D, where EDV = end-diastolic volume. Ejection fraction is the ratio of stroke volume (SV) and EDV, allowing this equation to be simplified to VFT = 4 &#215; (1-&#946;) &#215; SV/(&#960;D3). Because VFT is dimensionless (volume/volume), this index allows direct comparison between patients of varying size without adjustment for weight or body surface area8. Optimal VFT ranges between 3.3 and 5.5 in healthy subjects8, and results are consistent with those obtained in fluid dynamics models3,32. VFT was shown to be &#8804; 2.0 in patients with depressed LV systolic function, findings that are also supported by theoretical predictions8. Reductions in VFT independently predicted morbidity and mortality in patients with heart failure30. Elevated LV afterload33, Alzheimer&#39;s disease34, abnormal diastolic function19, and replacement of the native mitral valve with a prosthesis35 have also been shown to decrease VFT. Measurement of VFT may also be useful to identify blood flow stasis or thrombosis in patients with acute myocardial infarction36,37.
Our group is interested in factors that affect LV filling efficiency during cardiac surgery38,39,40,41. We use standard two-dimensional and Doppler transesophageal echocardiography (TEE) to noninvasively derive the variables required to calculate VFT. In this report, we describe this methodology in detail and review our findings to date.

<table><tbody><tr><td>Echocardiography Machine</td><td>Philips Ultrasound, Bothall, WA</td><td>iE33</td><td></td></tr><tr><td>Transesophageal Echocardiography Probe</td><td>Philips Ultrasound, Bothall, WA</td><td>X7-2t</td><td></td></tr><tr><td>Statistical Software</td><td>AnalystSoft, Walnut, CA</td><td>StatPlus:mac Pro</td><td></td></tr></tbody></table>

noninvasive determination of vortex formation time using transesophageal echocardiography during cardiac surgery

Trans-mitral blood flow produces a three-dimensional rotational body of fluid, known as a vortex ring, that enhances the efficiency of left ventricular (LV) filling compared with a continuous linear jet. Vortex ring development is most often quantified with vortex formation time (VFT), a dimensionless parameter based on fluid ejection from a rigid tube. Our group is interested in factors that affect LV filling efficiency during cardiac surgery. In this report, we describe how to use standard two-dimensional (2D) and Doppler transesophageal echocardiography (TEE) to noninvasively derive the variables needed to calculate VFT. We calculate atrial filling fraction (&#946;) from velocity-time integrals of trans-mitral early LV filling and atrial systole blood flow velocity waveforms measured in the mid-esophageal four-chamber TEE view. Stroke volume (SV) is calculated as the product of the diameter of the LV outflow track measured in the mid-esophageal long axis TEE view and the velocity-time integral of blood flow through the outflow track determined in the deep transgastric view using pulse-wave Doppler. Finally, mitral valve diameter (D) is determined as the average of major and minor axis lengths measured in orthogonal mid-esophageal bicommissural and long axis imaging planes, respectively. VFT is then calculated as 4 &#215; (1-&#946;) &#215; SV/(&#960;D3). We have used this technique to analyze VFT in several groups of patients with differing cardiac abnormalities. We discuss our application of this technique and its potential limitations and also review our results to date. Noninvasive measurement of VFT using TEE is straightforward in anesthetized patients undergoing cardiac surgery. The technique may allow cardiac anesthesiologists and surgeons to assess the impact of pathological conditions and surgical interventions on LV filling efficiency in real time.

The current technique allowed us to reliably measure VFT during cardiac surgery under a variety of clinical conditions by obtaining each determinant from blood flow and dimensional recordings in standard TEE imaging planes. A pulse-wave Doppler sample volume was placed at the tips of the mitral leaflets in the mid-esophageal four-chamber view to obtain the trans-mitral blood flow velocity profile necessary to calculate atrial filling fraction (&#946;; Figure 1). Stroke volume was determined using the continuity equation (velocity-time integral of the LV outflow track blood flow velocity waveform multiplied by the area of the outflow track) and LV outflow track diameter was measured in the mid-esophageal LV long-axis view (Figure 2A), whereas blood flow through the outflow tract was determined in the deep transgastric short axis imaging plane (Figure 2B). Finally, average mitral valve diameter was calculated as the average of major and minor axis diameters measured in the mid-esophageal bicommissural and LV long-axis planes (Figure 3A and 3B, respectively). Measurement of VFT was associated with intra- and interobserver variability of 5% and 7%, respectively, similar to other indices of dimension and blood flow measured using TEE (data not shown). Using this technique, we first showed that exposure to CPB reduced VFT (5.3 &#177; 1.8 before vs. 4.0 &#177; 1.5 15 minutes after bypass, p &#60; 0.05; Figure 4) in patients undergoing coronary artery surgery. VFT recovered to baseline values within 60 minutes after CPB. An increase in &#946; (0.33 &#177; 0.04 before vs. 0.41 &#177; 0.07 15 minutes after CPB, p &#60; 0.05) consistent with greater atrial contribution to LV filling was primarily responsible for the decline in VFT because SV and mitral valve diameter remained unchanged.
We also showed that a decrease in VFT occurs in patients with severe aortic valve stenosis and LV pressure-overload hypertrophy compared with those with normal LV wall thickness (3.0 &#177; 0.6 vs. 4.3 &#177; 0.5, respectively; p &#60; 0.05; Figure 5). Early LV filling was attenuated (e.g., E/A, 0.77 &#177; 0.11 compared with 1.23 &#177; 0.13; &#946;, 0.43 &#177; 0.09 compared with 0.35 &#177; 0.02; p &#60; 0.05 for each), and SV was reduced (72 &#177; 12 mL compared with 95 &#177; 10 mL; p &#60; 0.05) in patients with vs. without LV hypertrophy; however, mitral valve diameter was similar between groups. A significant inverse correlation between VFT and posterior wall thickness (PWT) was shown with linear regression analysis (VFT = -2.57 &#215; PWT + 6.81; r = 0.408; p = 0.017). In addition, our results using this technique demonstrated that the presence compared to absence of moderate aortic insufficiency in patients with severe aortic valve stenosis increased VFT (5.7 &#177; 1.7 vs. 3.0 &#177; 0.6, respectively; p &#60; 0.05; Figure 5) concomitant with a decrease in mitral valve diameter (2.2 &#177; 0.2 vs. 2.6 &#177; 0.1 cm, respectively; p &#60; 0.05), whereas indices of LV diastolic dysfunction and SV were similar between groups. Finally, we were able to use our technique of measuring VFT to show that VFT was lower in octogenarians compared with younger patients (3.0 &#177; 0.9 vs. 4.5 &#177; 1.2; p &#60; 0.05) concomitant with an impaired relaxation pattern of LV diastolic dysfunction (e.g., E/A of 0.81 &#177; 0.16 vs.1.29 &#177; 0.19; &#946; of 0.44 &#177; 0.05 vs.0.35 &#177; 0.03, p &#60; 0.05 for each). A significant inverse correlation between VFT and age was also demonstrated (VFT = -0.0627 &#215; age + 8.24; r = 0.639; p = 0.0139; Figure 6).
<img alt="Figure 1" class="xfigimg" src="/files/ftp_upload/58374/58374fig1.jpg" /> 
Figure 1: Trans-mitral blood flow velocity waveforms. Trans-mitral blood flow velocity waveforms during early LV filling (E) and atrial systole (A) obtained in the mid-esophageal four-chamber TEE view (left side of image); the area of each envelope was integrated using the equipment&#39;s software to obtain velocity-time integrals (right side of image) and the atrial filling fraction (&#946;) was calculated. In this example, &#946; = 4.28 cm/(4.28 cm + 6.73 cm) = 0.39 (see text). <a href="https://www.jove.com/files/ftp_upload/58374/58374fig1large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 2" class="xfigimg" src="/files/ftp_upload/58374/58374fig2.jpg" /> 
Figure 2: Measurement of LV outflow track diameter. Measurement of LV outflow track diameter during mid-systole in the aortic valve long axis TEE view (A) (diameter = 2.23 cm); (B) blood flow velocity was measured in the in the distal LV outflow track using the deep transgastric long axis TEE view and the area of the resulting envelope (left side of panel B) integrated using the equipment&#39;s software to obtain a velocity-time integral (white arrow, right side of panel B). In this example, stroke volume = &#960;/4 &#215; (2.23 cm)2 &#215; 19.8 cm = 77 mL (see text). <a href="https://www.jove.com/files/ftp_upload/58374/58374fig2large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 3" class="xfigimg" src="/files/ftp_upload/58374/58374fig3.jpg" /> 
Figure 3: Average mitral valve diameter was calculated as the average of major and minor axis diameters measured in the mid-esophageal bicommissural and LV long-axis planes. Mid-esophageal bicommissural (A) and LV outflow tract (B) TEE images were used to determine major (transcommissural anterior-lateral-posterior-medial) and minor (anterior-posterior) axis diameters, respectively. In this example, mitral valve diameter = (3.04 cm + 2.18 cm)/2 = 2.61 cm. This figure is reproduced with permission from Elsevier38. <a href="https://www.jove.com/files/ftp_upload/58374/58374fig3large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 4" class="xfigimg" src="/files/ftp_upload/58374/58374fig4.jpg" /> 
Figure 4: Temporal changes in VFT. Temporal changes in VFT before and 15, 30, and 60 minutes after cardiopulmonary bypass (CPB) in patients undergoing coronary artery surgery; *indicates significant (p &#60; 0.05) difference from the &#34;before CPB&#34; measurement. <a href="https://www.jove.com/files/ftp_upload/58374/58374fig4large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 5" class="xfigimg" src="/files/ftp_upload/58374/58374fig5.jpg" /> 
Figure 5: Effects of LV pressure-overload hypertrophy resulting from severe aortic valve stenosis in the absence (-) or presence (+) of moderate aortic insufficiency (AI) in patients undergoing aortic valve replacement. Patients with normal LV wall thickness undergoing coronary artery surgery served as controls (normal). *Significantly (p &#60; 0.05) different from normal; &#8224;Significantly (p &#60; 0.05) different from both normal and hypertrophy-AI. <a href="https://www.jove.com/files/ftp_upload/58374/58374fig5large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 6" class="xfigimg" src="/files/ftp_upload/58374/58374fig6.jpg" /> 
Figure 6: Correlation between age and VFT in 14 patients undergoing coronary artery surgery. VFT = -0.0627 &#215; age + 8.24; r = 0.639; p = 0.0139. <a href="https://www.jove.com/files/ftp_upload/58374/58374fig6large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>

Watch this Scientific Journal Video about Noninvasive Determination of Vortex Formation Time Using Transesophageal Echocardiography During Cardiac Surgery at JoVE.com

Noninvasive Determination of Vortex Formation Time Using Transesophageal Echocardiography During Cardiac Surgery

We describe a protocol to measure vortex formation time, an index of left ventricular filling efficiency, using standard transesophageal echocardiography techniques in patients undergoing cardiac surgery. We apply this technique to analyze vortex formation time in several groups of patients with differing cardiac pathologies.

Trans-mitral blood flow produces a three-dimensional rotational body of fluid, known as a vortex ring, that enhances the efficiency of left ventricular ...

noninvasive-determination-vortex-formation-time-using-transesophageal

Universidad Científica del Sur

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JoVE Journal

Medicine

7.9K Views.  Clement J. Zablocki Veterans Affairs Medical Center. We describe a protocol to measure vortex formation time, an index of left ventricular filling efficiency, using standard transesophageal echocardiography techniques in patients undergoing cardiac surgery. We apply this technique to analyze vortex formation time in several groups of patients with differing cardiac pathologies.

Video: Noninvasive Determination of Vortex Formation Time Using Transesophageal Echocardiography During Cardiac Surgery

Transthoracic Echocardiography in Mice

In recent years, murine models have become the primary avenue for studying the molecular mechanisms of cardiac dysfunction resulting from changes in gene expression. Transgenic and gene targeting methods can be used to generate mice with altered cardiac size and function,1-3 and as a result, in vivo techniques are needed to evaluate their cardiac phenotype. Transthoracic echocardiography, pulse wave Doppler (PWD), and tissue Doppler imaging (TDI) can be used to provide dimensional measurements of the mouse heart and to quantify the degree of cardiac systolic and diastolic performance. Two-dimensional imaging is used to detect abnormal anatomy or movements of the left ventricle, whereas M-mode echo is used for quantification of cardiac dimensions and contractility.4,5 In addition, PWD is used to quantify localized velocity of turbulent flow,6 whereas TDI is used to measure the velocity of myocardial motion.7 Thus, transthoracic echocardiography offers a comprehensive method for the noninvasive evaluation of cardiac function in mice.

Transthoracic echocardiography offers a noninvasive method for the evaluation of cardiac function in mice. A combination of ultrasound and Doppler imaging modalities can be used to obtain dimensional measurements of the heart and intracardiac blood flow, which together provide an assessment of cardiac systolic and diastolic performance.

In recent years, murine models have become the primary avenue for studying the molecular mechanisms of cardiac dysfunction resulting from changes in gene ...

High-frequency High-resolution Echocardiography: First Evidence on Non-invasive Repeated Measure of Myocardial Strain, Contractility, and Mitral Regurgitation in the Ischemia-reperfused Murine Heart

Ischemia-reperfusion (IR) was surgically performed in murine hearts which were then subjected to repeated imaging to monitor temporal changes in functional parameters of key clinical significance. Two-dimensional movies were acquired at high frame rate (8 kHz) and were utilized to estimate high-quality myocardial strain. Two-dimensional elastograms (strain images), as well as strain profiles, were visualized. Results were powerful in quantitatively assessing IR-induced changes in cardiac events including left-ventricular (LV) contraction, LV relaxation and isovolumetric phases of both pre-IR and post-IR beating hearts in intact mice. In addition, compromised sector-wise wall motion and anatomical deformation in the infarcted myocardium were visualized.  The elastograms were uniquely able to provide information on the following parameters in addition to standard physiological indices that are known to be affected by myocardial infarction in the mouse: internal diameters of mitral valve orifice and aorta, effective regurgitant orifice, myocardial strain (circumferential as well as radial), turbulence in blood flow pattern as revealed by the color Doppler movies and velocity profiles, asynchrony in LV sector, and changes in the length and direction of vectors demonstrating slower and asymmetrical wall movement. This work emphasizes on the visual demonstration of how such analyses are performed. 

High-frequency High-resolution Echocardiography: First Evidence on Non-invasive Repeated Measure of Myocardial Strain, Contractility, and Mitral Regurgitation in the Ischemia-reperfused Murine Heart 

High frequency Doppler ultrasound is a novel technology for assessing regional myocardial function. This work presents first evidence demonstrating applicability of this versatile imaging platform for the repeated measure of myocardial strain, dp/dt, and mitral regurgitation in the ischemia-reperfused (IR) murine heart.

Ischemia-reperfusion (IR) was surgically performed in murine hearts which were then subjected to repeated imaging to monitor temporal changes in ...

Transthoracic Speckle Tracking Echocardiography for the Quantitative Assessment of Left Ventricular Myocardial Deformation

The value of conventional echocardiography is limited by differences in inter-individual image interpretation and therefore largely dependent on the examiners&#39; expertise. Speckle tracking Echocardiography (STE) is a promising but technically challenging method that can be used to quantitatively assess regional and global systolic and diastolic myocardial performance. Myocardial strain and strain rate can be measured in all three dimensions&#160;&#8212; radial, circumferential, longitudinal &#8212; of myocardial deformation. Standard cross-sectional two-dimensional B-mode images are recorded and subsequently postprocessed by automated continuous frame-by-frame tracking and motion analysis of speckles within the myocardium. Images are recorded as digital loops and synchronized to a 3-lead EKG for timing purposes. Longitudinal deformation is assessed in the apical 4-, 3-, and 2-chamber views. Circumferential and radial deformation are measured in the parasternal short axis plane.
Optimal image quality and accurate tissue tracking are paramount for the correct determination of myocardial performance parameters. Utilizing transthoracic STE in a healthy volunteer, the present article is a detailed outline of the essential steps and potential pitfalls of quantitative echocardiographic myocardial deformation analysis.

Speckle tracking echocardiography is an emerging diagnostic imaging technique for the quantitative assessment of global and regional myocardial performance. Standard view echocardiographic motion images are recorded and deformation parameters are subsequently measured by automated continuous frame-by-frame tracking and motion analysis of speckles within the B-mode images of the myocardium.

The value of conventional echocardiography is limited by differences in inter-individual image interpretation and therefore largely dependent on the ...

Three-Dimensional Echocardiographic Method for the Visualization and Assessment of Specific Parameters of the Pulmonary Veins

The dimensions of the pulmonary veins are important parameters when planning pulmonary vein isolation (PVI), especially with the cryoballoon ablation technique. Acknowledging the dimensions and anatomical variations of the pulmonary veins (PVs) may improve the outcome of the intervention. Conventional 2D transoesophageal echocardiography can only provide limited data about the dimensions of the PVs; however, 3D echocardiography can further evaluate relevant diameters and areas of the PVs, as well as their spatial relationship to surrounding structures. In previous literature data, parameters influencing the success rate of PVI have already been identified. These are the left lateral ridge, the intervenous ridge, the ostial area of the PVs and the ovality index of the ostium. Proper imaging of the PVs by 3D echocardiography is a technically challenging method. One crucial step is the collection of images. Three individual transducer positions are necessary to visualize the important structures; these are the left lateral ridge, the ostium of the PVs and the intervenous ridge of the left and right PVs. Next, 3D images are acquired and saved as digital loops. These datasets are cropped, which result in the en face views displaying spatial relationships. This step can also be employed to determine the anatomical variations of the PVs. Finally, multiplanar reconstructions are created to measure each individual parameter of the PVs.
Optimal quality and orientation of the acquired images are paramount for the appropriate assessment of PV anatomy. In the present work, we examined the 3D visibility of the PVs and the suitability of the above method in 80 patients. The aim was to provide a detailed outline of the essential steps and potential pitfalls of PV visualization and assessment with 3D echocardiography.

The dimensions of the pulmonary veins (PV) are important parameters when planning pulmonary vein isolation. 2D transoesophageal echocardiography can only provide limited data about the PVs; however, 3D echocardiography can evaluate relevant diameters and areas of the PVs, as well as their spatial relationship to surrounding structures.

The dimensions of the pulmonary veins are important parameters when planning pulmonary vein isolation (PVI), especially with the cryoballoon ablation ...

Bioengineering

Transthoracic Echocardiographic Examination in the Rabbit Model

Large animal models such as the rabbit are valuable for translational preclinical research. Rabbits have a similar cardiac electrophysiology compared to that of humans and that of other large animal models such as dogs and pigs. However, the rabbit model has the additional advantage of lower maintenance costs compared to other large animal models. The longitudinal evaluation of cardiac function using echocardiography, when appropriately implemented, is a useful methodology for preclinical assessment of novel therapies for heart failure with reduced ejection fraction (e.g. cardiac regeneration). The correct use of this non-invasive tool requires the implementation of a standardized examination protocol following international guidelines. Here we describe, step by step, a detailed protocol supervised by veterinary cardiologists for performing echocardiography in the rabbit model, and demonstrate how to correctly obtain the different echocardiographic views and imaging planes, as well as the different imaging modes available in a clinical echocardiography system routinely used in human and veterinary patients.

Here we describe, step by step, a detailed protocol for performing echocardiography in the rabbit model. We show how to correctly obtain the different echocardiographic views and imaging planes, as well as the different imaging modes available in a clinical echocardiography system routinely used in human and veterinary patients.

Large animal models such as the rabbit are valuable for translational preclinical research. Rabbits have a similar cardiac electrophysiology compared to ...

Echocardiographic Evaluation of Atrial Communications before Transcatheter Closure

Transthoracic (TTE) and transesophageal echocardiography (TEE) is the standard imaging method for atrial septal defect (ASD) and patent foramen ovale (PFO) detection, for patient selection for transcatheter ASD/PFO closure,&#160;for intraoperative guidance and for long-term follow-up. The size, shape, location and the number of the atrial communications schould be determined. The accuracy of PFO detection can be improved by using agitated saline together with maneuvers to transiently increase the right atrial (RA) pressure. The appearance of microbubbles in the left atrium (LA) within 3 cardiac cycles after opacification of the RA is considered positive for the presence of an intracardiac shunt. Three dimensional TEE identifies further septal fenestrations and describes the dynamic morphology of ASD/PFO and atrial septal aneurysm. Follow-up evaluations with TTE is recommended at 1, 6, and 12 months after the procedure, with a subsequent evaluation every year. Previous studies showed an increased incidence of atrial arrhythmias early after device closure. Speckle tracking analysis may help to understand functional left atrial remodeling following percutaneous closure and its impact on atrial arrhythmias.

Transthoracic (TTE) and transesophageal (TEE) echocardiography represent the basic imaging tools for interatrial septum examination. Three dimensional (3D) TEE provides incremental information in the assessment of the interatrial septum. Further advanced echocardiography techniques using speckle tracking echocardiography are applied for sensitive volumetric and functional assessment of the heart chambers.&#160;

Transthoracic (TTE) and transesophageal echocardiography (TEE) is the standard imaging method for atrial septal defect (ASD) and patent foramen ovale ...

Transthoracic Echocardiography to Assess Post-Resuscitation Left Ventricular Dysfunction After Acute Myocardial Infarction and Cardiac Arrest in Pigs

One of the main causes of out-of-hospital cardiac arrest is acute myocardial infarction (AMI). After successful resuscitation from cardiac arrest, approximately 70% of patients die before hospital discharge due to post-resuscitation myocardial and cerebral dysfunction. In experimental models, myocardial dysfunction after cardiac arrest, characterized by an impairment in both left ventricular (LV) systolic and diastolic function, has been described as reversible but very little data are available in cardiac arrest models associated with AMI in pigs. Transthoracic echocardiography is the first-line diagnostic test for the assessment of myocardial dysfunction, structural changes and/or AMI extension. In this pig model of ischemic cardiac arrest, echocardiography was done at baseline and 2-4 and 96 hours after resuscitation. In the acute phase, the examinations are done in anesthetized, mechanically ventilated pigs (weight 39.8 &#177; 0.6 kg) and ECG is recorded continuously. Mono- and bi-dimensional, Doppler and tissue Doppler recordings are acquired. Aortic and left atrium diameter, end-systolic and end-diastolic left ventricular wall thicknesses, end-diastolic and end-systolic diameters and shortening fraction (SF) are measured. Apical 2-, 3-, 4-, and 5-chamber views are acquired, LV volumes and ejection fraction are calculated. Segmental wall motion analysis is done to detect the localization and estimate the extent of myocardial infarction. Pulsed Wave Doppler echocardiography is used to record trans-mitral flow velocities from a 4-apical chamber view and trans-aortic flow from a 5-chamber view to calculate LV cardiac output (CO) and stroke volume (SV). Tissue Doppler Imaging (TDI) of LV lateral and septal mitral anulus is recorded (TDI septal and lateral s&#39;, e&#39;, a&#39; velocities). All the recordings and measurements are done according to the recommendations of the American and European Societies of Echocardiography Guidelines.

Transthoracic echocardiography is the first-line diagnostic test for post-resuscitation left ventricular dysfunction and structural changes in a pig model of cardiac arrest.

One of the main causes of out-of-hospital cardiac arrest is acute myocardial infarction (AMI). After successful resuscitation from cardiac arrest, ...

Hemodynamic Precision in the Neonatal Intensive Care Unit using Targeted Neonatal Echocardiography

Targeted neonatal echocardiography (TnECHO) refers to the use of comprehensive echocardiographic evaluation and physiologic data to obtain accurate, reliable, and real-time information on developmental hemodynamics in sick newborns. The comprehensive assessment is based on a multiparametric approach that overcomes the reliability issues of individual measurements, allows for earlier recognition of cardiovascular compromise and promotes enhanced diagnostic precision and timely management. TnECHO-driven research has led to an enhanced understanding of the mechanisms of illness and the development of predictive models to identify at-risk populations. This information may then be used to formulate a diagnostic impression and provide individualized guidance for the selection of cardiovascular therapies. TnECHO is based on the expert consultative model in which a neonatologist, with advanced training in neonatal hemodynamics, performs comprehensive and standardized TnECHO assessments. The distinction from point of care ultrasonography (POCUS), which provides limited and brief one-time assessments, is important. Neonatal hemodynamics training is a 1-year structured program designed to optimize image acquisition, measurement analysis, and hemodynamic knowledge (physiology, pharmacotherapy) to support cardiovascular decision-making. Neonatologists with hemodynamic expertise are trained to recognize deviations from normal anatomy and appropriately refer cases of possible structural abnormalities. We provide an outline of neonatal hemodynamics training, the standardized TnECHO imaging protocol, and an example of representative echo findings in a hemodynamically significant patent ductus arteriosus.

Presented here is a protocol to perform comprehensive neonatal echocardiography by trained neonatologists in the neonatal intensive care unit. The trained individuals provide longitudinal assessments of heart function, systemic and pulmonary hemodynamics in a consultative role. The manuscript also describes the requirements to become a fully trained neonatal hemodynamics specialist.

Targeted neonatal echocardiography (TnECHO) refers to the use of comprehensive echocardiographic evaluation and physiologic data to obtain accurate, ...

Advancements in Echocardiography-Derived Blood Speckle Imaging Technology

Assessing Intracardiac Vortices with High Frame-Rate Echocardiography-Derived Blood Speckle Imaging in Newborns

The left ventricle (LV) has a unique pattern of hemodynamic filling. During diastole, a rotational body or ring of fluid known as a vortex is formed due to the chiral geometry of the heart. A vortex is reported to have a role in conserving the kinetic energy of blood flow entering into the LV. Recent studies have shown that LV vortices may have prognostic value in describing diastolic function at rest in neonatal, pediatric, and adult populations, and may help with earlier subclinical intervention. However, the visualization and characterization of the vortex remain minimally explored. A number of imaging modalities have been utilized for visualizing and describing intracardiac blood flow patterns and vortex rings. In this article, a technique known as blood speckle imaging (BSI) is of particular interest. BSI is derived from high-frame rate color Doppler echocardiography and provides several advantages over other modalities. Namely, BSI is an inexpensive and noninvasive bedside tool that does not rely on contrast agents or extensive mathematical assumptions. This work presents a detailed step-by-step application of the BSI methodology used in our laboratory. The clinical utility of BSI is still in its early stages, but has shown promise within the pediatric and neonatal populations for describing diastolic function in volume-overloaded hearts. A secondary aim of this study is thus to discuss recent and future clinical work with this imaging technology.

Author Spotlight: Advancing Neonatal Cardiac Diagnostics with Echocardiography-Derived Blood Speckle Imaging 

The present protocol uses echocardiography-derived blood speckle imaging technology to visualize intracardiac hemodynamics in newborns. The clinical utility of this technology is explored, the rotational body of fluid within the left ventricle (known as a vortex) is accessed, and its significance in understanding diastology is determined.

The left ventricle (LV) has a unique pattern of hemodynamic filling. During diastole, a rotational body or ring of fluid known as a vortex is formed due ...

Point-of-Care Ultrasound for Peripheral Veno-Arterial Extracorporeal Membrane Oxygenation Without Left Ventricular Venting

Over the past several decades, veno-arterial extracorporeal membrane oxygenation (V-A ECMO) has become a critical tool in the management of patients with severe cardiogenic shock and cardiopulmonary failure. Due to the inherent instability of these patients, their transport away from intensive care units is fraught with risk. As a result, bedside diagnostic tools are essential for their daily care. One such tool is point-of-care ultrasound (POCUS) of the heart, which can non-invasively assess several parameters: left ventricular (LV) performance (size, systolic function, stroke volume, aortic valve opening), right ventricular (RV) performance (size, systolic function), and the presence of intracardiac thrombus. Additionally, POCUS can assist in evaluating readiness for V-A ECMO weaning and eventual decannulation. Despite its potential, the use of POCUS in the context of V-A ECMO remains inconsistent due to variability in provider training. This study aims to address this gap by detailing POCUS image acquisition in V-A ECMO, particularly in the absence of LV venting. It covers key aspects such as patient positioning, transducer selection, probe placement, acquisition sequence, and image optimization.

This protocol outlines the use of point-of-care ultrasound (POCUS) to monitor patients on peripheral veno-arterial extracorporeal membrane oxygenation (V-A ECMO) without left ventricular venting. It evaluates left ventricular distension, intracardiac or aortic root thrombus, and identifies useful cardiac POCUS parameters for weaning from V-A ECMO.

Over the past several decades, veno-arterial extracorporeal membrane oxygenation (V-A ECMO) has become a critical tool in the management of patients with ...

Noninvasive Determination of Vortex Formation Time Using Transesophageal Echocardiography During Cardiac Surgery

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Explore More Videos

Transthoracic Echocardiography in Mice

High-frequency High-resolution Echocardiography: First Evidence on Non-invasive Repeated Measure of Myocardial Strain, Contractility, and Mitral Regurgitation in the Ischemia-reperfused Murine Heart

Transthoracic Speckle Tracking Echocardiography for the Quantitative Assessment of Left Ventricular Myocardial Deformation

Three-Dimensional Echocardiographic Method for the Visualization and Assessment of Specific Parameters of the Pulmonary Veins

Transthoracic Echocardiographic Examination in the Rabbit Model

Echocardiographic Evaluation of Atrial Communications before Transcatheter Closure

Transthoracic Echocardiography to Assess Post-Resuscitation Left Ventricular Dysfunction After Acute Myocardial Infarction and Cardiac Arrest in Pigs

Hemodynamic Precision in the Neonatal Intensive Care Unit using Targeted Neonatal Echocardiography

Assessing Intracardiac Vortices with High Frame-Rate Echocardiography-Derived Blood Speckle Imaging in Newborns

Point-of-Care Ultrasound for Peripheral Veno-Arterial Extracorporeal Membrane Oxygenation Without Left Ventricular Venting