Liset N. Stoletniy

Value of QT Dispersion in the Interpretation of Exercise Stress Test in Women

BACKGROUND Exercise testing in women is associated with a high incidence of false-positive ECG changes and should be combined with an imaging study. The QT dispersion (QTD), recorded as the difference between maximum and minimum QT intervals on a 12-lead ECG, is sensitive to myocardial ischemia and may improve the accuracy of exercise testing in women. METHODS AND RESULTS Exercise ECGs were analyzed in 64 women who had undergone exercise ECG and coronary angiography for clinical indications: 20 patients with normal exercise stress test and nonsignificant (< or = 50% diameter narrowing of a major epicardial coronary artery) coronary artery disease (CAD) on angiography (true-negative; TN group), 20 patients with positive exercise stress tests (> or = 1 mm ST-segment depression or reversible perfusion defects) and significant CAD (true-positive; TP group), and 24 patients with positive exercise stress tests but no significant CAD (false-positive; FP group). The exercise QTD was 45+/-15 ms in TN, 80+/-23 ms in TP (P<.0001 versus TP), and 41+/-14 ms in FP (P=NS versus TN and <.0001 versus TP) groups. A stress QTD of > 60 ms had a sensitivity of 70% and specificity of 95% for the diagnosis of significant CAD compared with 55% (P<.05) and 63% (P<.01), respectively, for > or = 1 mm ST-segment depression during stress. When QTD of > 60 ms was added to ST-segment depression as a condition for positive test, the specificity increased to 100%. CONCLUSIONS Exercise QTD is an easily measurable ECG variable that significantly increases the accuracy of exercise testing in women.

Usefulness of QTc dispersion in interpreting exercise electrocardiograms

The ECG QT interval is a measure of the duration ofventricular repolarization and is sensitive to myocardial ischemia. The interlead variation in the 12-lead ECG is referred ~to as QT dispersion. The QT or QTc dispersion is a noninvasive measure of regional variation in ventricular recovery time. Increased dispersion ofventricular recovery time has been associated with increased risk of serious arrhythmias, 1-3 particularly in conditions in which QT is prolonged, including congenital long QT syndrome, 4 drug toxicity, hypertrophic cardiomyopathy, 5 and post-myocardial infarction arrhythmias. 6 Class Ia antiarrhythmic agents are associated with increased nonhomogeneous, regional QT-interva ! prolongation, giving rise to widened QT dispersion, and that this widened dispersion is associated with increased risk of torsades de pointes. On the other hand, class III drugs such as amiodarone and sotalol have a homogeneous prolongation of QT and are not associated with torsades de pointes. 7 The QT dispersion is also increased in patients with myocardial infarction compared with dispersion in control subjects and may be reduced by the class III antiarrhythmic agent. This pattern may account for the salutary effects of class III antiarrhythmic agents on ventricular arrhythmias after myocardial infarction. An increase in interlead QT variability or dispersion on the surface of 12-lead ECG has been associated with regional ischemia and wall motion abnormality, s Some data support the theory that successful thrombolysis is associated with less QT dispersion in post-acute myocardial infarction patients. 9 We hypothesized that exercise-induced myocardial ischemia could change QT interval regionally in the area of ischemia, giving rise to an increased QT dispersion in the 12-lead electrocardiogram, which may be helpful in the interpretation of exercise stress tests. Methods. We studied 56 unselected patients (55 men and 1 woman) who had undergone symptom-limited treadmill exercise tests for clinical indications and were not taking antiarrhythmic agents. On the basis of the results of the stress test and the results of coronary angiograms in patients with positive test results, patients were divided into three groups: (1) The normal (NL) group consisted of 23 patients with a mean age of 51 -+ 11 years who had nor-

Lack of relationship between microvascular and macrovascular disease in heart transplant recipients.

Background A key determinant of long-term survival in heart transplant recipients is the development of coronary vasculopathy. Both coronary macrovascular and microvascular disease are prognostically important. However, the relationship between these in transplant patients and the determinants of microvascular disease are not known. Methods We reviewed the simultaneously obtained endomyocardial biopsies and intravascular ultrasound (IVUS) images of coronary arteries in 33 heart transplant recipients. Coronary microvascular disease was classified by light microscopy into four grades based on thickening of endothelial cell layer and stenotic versus nonstenotic medial wall thickening. Macrovascular disease was evaluated from IVUS studies and assigned into one of five grades based on the Stanford classification. Coronary microvascular and macrovascular diseases were compared. Results Age at transplantation was 26 (18) years; 67% were men, and the average time to posttransplantation study was 4 years. Endomyocardial biopsy revealed more advanced grade C and D microvascular disease in 45% and 36% of the patients, respectively. However, IVUS analysis for macrovascular disease revealed mostly lesser changes with grade 1 in 12%, grade 2 in 61%, and grade 3 in 21%. There was no significant correlation between grades of microvascular and macrovascular disease (P=0.10). Microvascular disease correlated positively with donor age (P=0.06) and treatment with tacrolimus (0=0.02) and statins (P=0.05). Conclusions There is a poor relationship between coronary microvascular and macrovascular disease in patients with cardiac transplants, likely indicating divergent pathogenetic mechanisms. Microvascular disease increases with donor age. There is an intriguing positive relationship between microvascular disease and treatment with statins and tacrolimus.

Clinical and echocardiographic correlates of mitral E-wave transmission inside the left ventricle: Potential insights into left ventricular diastolic function

The mitral inflow wave is initially directed to the left ventricular apex and then turns around facing the left ventricular outflow tract. The E and A waves are transmitted to the left ventricular outflow tract where they are registered as Er and Ar waves, respectively. We hypothesized that the E-wave transit time to the left ventricular outflow tract recorded as the E-Er interval may depend on left ventricular early diastolic performance such as relaxation. This hypothesis was tested in clinical settings known to have abnormal left ventricular relaxation. Mitral E and left ventricular outflow tract Er waves were recorded with pulsed wave Doppler technique in 63 subjects: 25 healthy subjects, 18 patients with secondary left ventricular hypertrophy, and 20 patients with hypertrophic cardiomyopathy. The E-Er interval was measured from the onset of E wave to the onset of Er wave timed to the R wave of the electrocardiogram. The E-Er interval ranged from 45 to 300 msec: 96 +/- 28 msec in the controls, 127 +/- 46 msec in patients with left ventricular hypertrophy (p = 0.0091 versus controls), and 179 +/- 57 msec in patients with hypertrophic cardiomyopathy (p < 0.0001 versus controls). It correlated with left ventricular free wall thickness (r = 0.42, p = 0.0006), thickness of the ventricular septum (r = 0.43, p = 0.0004), left ventricular end-diastolic diameter (r = -0.38, p = 0.0022), left ventricular end-systolic diameter (r = -0.55, p < 0.0001), left ventricular isovolumic relaxation time (r = 0.39, p = 0.0063), RR interval (r = 0.28, p = 0.045), mitral E/A velocity ratio (r = -0.33, p = 0.010), and E-wave deceleration time (r = 0.38, p < 0.0044) but not with age. Multivariate analysis with all the previously mentioned variables and the group the patient belonged to as the dichotomous variable showed that the grouping variable was the sole independent determinant of the E-Er interval (multiple r = 0.74). The E-Er interval is an easily measurable Doppler parameter which is increased in left ventricular hypertrophy and hypertrophic cardiomyopathy. It is related to left ventricular wall thickness, left ventricular isovolumic relaxation time, mitral E/A velocity ratio, and E-wave deceleration time and may provide useful insight into left ventricular early diastolic performance-possibly the relaxation process.

A practical guide to cardiovascular 3D printing in clinical practice: Overview and examples

The advent of more advanced 3D image processing, reconstruction, and a variety of three-dimensional (3D) printing technologies using different materials has made rapid and fairly affordable anatomically accurate models much more achievable. These models show great promise in facilitating procedural and surgical planning for complex congenital and structural heart disease. Refinements in 3D printing technology lend itself to advanced applications in the fields of bio-printing, hemodynamic modeling, and implantable devices. As a novel technology with a large variability in software, processing tools and printing techniques, there is not a standardized method by which a clinician can go from an imaging data-set to a complete model. Furthermore, anatomy of interest and how the model is used can determine the most appropriate technology. In this over-view we discuss, from the standpoint of a clinical professional, image acquisition, processing, and segmentation by which a printable file is created. We then review the various printing technologies, advantages and disadvantages when printing the completed model file, and describe clinical scenarios where 3D printing can be utilized to address therapeutic challenges.

An Integrated Measure of Left Ventricular Diastolic Function Based on Relative Rates of Mitral E and A Wave Propagation

BACKGROUND AND OBJECTIVES The mitral E wave propagation inside the left ventricle is slowed in patients with abnormal left ventricular (LV) relaxation with a prolongation of its transit time to the LV outflow tract (T(e)). On the contrary, the mitral A wave propagation is faster in those with elevated LV end-diastolic stiffness, resulting in a shortening of its transit time (T(a)). We hypothesized that the T(e)/T(a) ratio may serve an integrated measure of global LV diastolic function. METHODS AND RESULTS The T(e)/T(a) ratio was measured with Doppler echocardiography in 94 subjects: 25 normal subjects, 38 patients with LV hypertrophy (18 with secondary LV hypertrophy and 20 with hypertrophic cardiomyopathy), and 31 patients undergoing left heart catheterization for clinical indications. The T(e)/T(a) ratio was 1. 98 +/- 0.61 in the normal subjects, 3.32 +/- 0.93 in patients with secondary LV hypertrophy (P <.0001 vs normal), and 3.18 +/- 1.36 in patients with hypertrophic cardiomyopathy (P =.0003 vs normal). In the invasive group the T(e)/T(a) ratio (range 0.56 to 3.60) correlated significantly with Tau (r = 0.76, P <.0001), peak negative dP/dt (r = -0.46, P =.01), the LV late diastolic stiffness index (r = 0.57, P =.0013), LV pre-A wave pressure (r = 0.46, P =. 0096), LV end-diastolic pressure (r = 0.58, P =.0007), and the amount of LV pressure rise with atrial systole (r = 0.52, P =.0032) but not with the heart rate. Tau and LV stiffness were its sole determinants by stepwise multiple regression (R = 0.82). CONCLUSIONS The ratio of mitral E and A wave transit times inside the LV (T(e)/T(a) ratio) is closely related to LV relaxation, its late diastolic stiffness, and filling pressures and gives valuable insights into LV diastolic performance.

Rates of Left Ventricular Isovolumic Pressure Rise and Fall from the Aortic Regurgitation Velocity Signal: Description of the Method and Validation in Human Beings

BACKGROUND Aortic regurgitation results from a pressure gradient across the aortic valve during left ventricular (LV) isovolumic relaxation, LV filling, and isovolumic contraction periods. Assuming the applicability of the simplified Bernoulli equation to this pressure-flow relation and constancy of aortic pressure during LV isovolumic relaxation and contraction periods, one can theoretically obtain estimates of the rates of LV isovolumic pressure fall and rise (deltaP/delta t) from the aortic regurgitation (AR) velocity signal. METHODS AND RESULTS Mitral regurgitation (MR) and AR signals were recorded by using the continuous wave Doppler technique in 26 patients with combined mitral and aortic regurgitant lesions. The LV negative deltaP/delta t was obtained by dividing the time taken for the AR velocity to rise from 1 m/sec to 2.5 m/sec into 21 mm Hg, which is the estimated LV pressure drop between these points. In a similar fashion, the LV positive deltaP/delta t was obtained between 2.5 m/sec and 1 m/sec of the fast decelerating portion of the AR signal. The LV negative deltaP/delta t by the AR method ranged from 420 to 3500 mm Hg/sec and correlated well with that obtained by the MR method obtained in a blinded fashion (r = 0.95, p < 0.0001). The mean (SD) difference between the two methods was 30 (129) mm Hg/sec. Similarly, the LV positive deltaP/delta t by the AR method (range 420 to 2625 mm Hg/sec) correlated closely with that obtained by the MR method (r = 0.93, p < 0.0001), with the mean (SD) difference between the two methods being 38 (138) mm Hg/sec. CONCLUSIONS Preliminary data presented in this study indicate the feasibility of obtaining a reliable estimate of LV positive and negative deltaP/delta t from the AR velocity profile. Thus the examination of the AR signal may give valuable insights into both LV systolic and diastolic functions.

Hemodynamic Basis of Mitral E Transmission in the Left Ventricular Cavity and Its Relation to the Left Ventricular Relaxation Process

Mitral E-wave transit time to the left ventricular outflow tract was measured as an E-Er interval in 30 subjects undergoing cardiac catheterization. The E-Er interval (range 30 to 190 ms) correlated with left ventricular peak negative dP/dt (r = -0.62, p = 0.0003) and tau (r = 0.74, p <0.0001) but not with left ventricular minimum, pre-A-wave, or end-diastolic pressures. We conclude that the E-Er interval is an easily obtainable Doppler measurement that reflects the left ventricular relaxation process.

Rapid Resolution of Coronary Artery Spasm Complicated by AcuteSystolic Heart Failure with Antirejection Therapy in Acute OrthotopicHeart Transplant Rejection

We report a case of rapid resolution of Coronary Artery Spasm (CAS) and improvement of systolic heart failure by antirejection therapy with methylprednisolone in the setting of acute Orthotopic Heart Transplant (OHT) rejection. The proposed mechanism of action is reduced microvascular inflammation from steroid therapy resulting in enhanced vasomotor response, resolution of coronary artery spasm, and improved hemodynamic. The case report has treatment implications for patients in acute OHT rejection with coronary artery spasm. Antirejection therapy with steroid may be helpful in treating life threatening cardiac conditions in patients with acute OHT rejection and coronary artery spasm.

Implantation of HeartMate II Left Ventricular Assist Device in a Single-Lung Patient

The use of mechanical assist devices has been established as an effective therapy for patients with end-stage heart failure. Implantable left ventricular assist devices are becoming more common in the clinical practice of cardiac surgery. This report illustrates the use of a HeartMate II (Thoratec Pleasanton, CA) left ventricular assist device in a patient with a single lung and dilated cardiomyopathy. To our knowledge, this is the first report of a left ventricular assist device placement in a patient with a prior pneumonectomy.