Left ventricular remodeling in human heart failure: quantitative echocardiographic assessment of 1,794 patients.

BACKGROUND: The left ventricle (LV) undergoes significant architectural remodeling in heart failure (HF). However, the fundamental associations between cardiac function and LV size and performance have not been thoroughly characterized in this population. We sought to define the adaptive remodeling that occurs in chronic human HF through the detailed analyses of a large quantitative echocardiography database. METHODS: Baseline echocardiograms were performed in 1,794 patients with HF across a broad range of ejection fraction (EF), from less than 10% to greater than 70%. Core lab measurements of LV volumes and length were made, from which EF, mass, sphericity indices, stroke volume (SV), and stroke work were derived. Spearman correlation coefficients and linear regression methods were used to determine the relationships between remodeling parameters. RESULTS: The median EF was 28.6% (IQR 21.9-37.0). Across a multitude of parameters of cardiac structure and function, indexed end-systolic volumes (ESVs) explained the greatest proportion of the variance in EF (R =-0.87, P < 0.0001). Systolic sphericity index and LV mass were also strongly correlated with EF (R =-0.62 and -0.63, P < 0.0001), reflective of the alterations in LV shape and size that occur as EF declines. SV was rigorously maintained across a broad spectrum of EF, until the EF fell below 20%, at which point SV decreased significantly (P < 0.0001). CONCLUSIONS: In chronic HF, the LV undergoes extensive structural adaptive remodeling in order to maintain SV across a broad range of EF. However, when the EF falls below 20%, further modulation of SV is no longer possible through alterations in ventricular architecture.

The utility of prescreening transesophageal echocardiograms: a prospective study.

BACKGROUND: Recent emphasis on the judicious use of imaging prompted the publication of the 2007 ACC/ASE Appropriateness Use Criteria (AUC) for Echocardiography. However, the intersection of the AUC with the safety and clinical use of transesophageal echocardiography (TEE) is not well established. METHODS: We reviewed 490 consecutive orders for TEEs for appropriateness, significant findings, and reasons for cancellation. RESULTS: We found that 79% (389/490) of ordered studies were performed and 21% (101/490) were not. The number of TEEs cancelled for safety reasons (n = 29) was similar to that cancelled for inappropriateness (n = 36). Only 2% (6/389) of those performed were inappropriate vs. 16% of those that were cancelled. New or unsuspected findings were obtained in half of all performed TEEs; the majority of which were ordered to detect cardiac source of embolism (CSE). CONCLUSIONS: The AUC should specifically consider the utility of clinician-based prescreening of TEEs to encourage appropriate use and safety. Furthermore, given the incremental value of TEE over transthoracic echocardiography in detection of CSE, in some cases, TEE may be considered an appropriate initial test for this indication.

Time-varying myocardial stress and systolic pressure-stress relationship: role in myocardial-arterial coupling in hypertension.

BACKGROUND: Myocardial afterload depends on left ventricular (LV) cavity size, pressure, and wall thickness, all of which change markedly throughout ejection. We assessed the relationship between instantaneous ejection-phase pressure and myocardial stress and the effect of arterial wave reflections on myocardial stress in hypertensive and normotensive adults. METHODS AND RESULTS: We studied 42 untreated hypertensive, 42 treated hypertensive, and 42 normotensive adults with normal LV ejection fraction. Time-resolved central pressure, flow, and LV geometry were measured with carotid tonometry, Doppler, and speckle-tracking echocardiography for computation of arterial load and time-varying circumferential and longitudinal myocardial stress. In all 3 groups, peak myocardial stress typically occurred in early systole (within the first 100 milliseconds of ejection), followed by a marked midsystolic shift in the pressure-stress relationship, which favored lower late systolic stress values (P<0.001) relative to pressure. The mean magnitude of this midsystolic shift was quantitatively important in all 3 groups (circumferential stress, 144 to 148 kdynes/cm(2)) and was independently predicted by a higher LV ejection fraction and ratio of LV end-diastolic cavity to wall volume. Time of peak myocardial stress independently correlated with time of the first systolic but not with time of the second systolic central pressure peak. CONCLUSIONS: Peak myocardial stress occurs in early systole, before important contributions of reflected waves to central pressure. In the presence of normal LV ejection fraction, a midsystolic shift in the pressure-stress relationship protects cardiomyocytes against excessive late systolic stress (despite pressure augmentation associated with wave reflections), a coupling mechanism that may be altered in various disease states.

Arterial pulsatile hemodynamic load induced by isometric exercise strongly predicts left ventricular mass in hypertension.

Although resting hemodynamic load has been extensively investigated as a determinant of left ventricular (LV) hypertrophy, little is known about the relationship between provoked hemodynamic load and the risk of LV hypertrophy. We studied central pressure-flow relations among 40 hypertensive and 19 normotensive adults using carotid applanation tonometry and Doppler echocardiography at rest and during a 40% maximal voluntary forearm contraction (handgrip) maneuver. Carotid-femoral pulse wave velocity (CF-PWV) was measured at rest. Hypertensive subjects demonstrated various abnormalities in resting and induced pulsatile load. Isometric exercise significantly increased systemic vascular resistance, aortic characteristic impedance (Zc), induced earlier wave reflections, increased augmentation index, and decreased total arterial compliance (TAC; all P < or = 0.01). In hypertensive subjects, CF-PWV was the strongest resting predictor of LV mass index (LVMI) and remained an independent predictor after adjustment for age, gender, systemic vascular resistance, reflection magnitude, aortic Zc, and TAC (beta = 2.52 m/s; P < 0.0001). Age, sex, CF-PWV, and resting hemodynamic indexes explained 48% of the interindividual variability in LVMI. In stepwise regression, TAC (beta = -17.85; P < 0.0001) during handgrip, Zc during handgrip (beta = -150; P < 0.0001), and the change in the timing of wave reflections during handgrip (beta = -0.63; P = 0.03) were independent predictors of LVMI. A model that included indexes of provoked hemodynamic load explained 68% of the interindividual variability in LVMI. Hemodynamic load provoked by isometric exercise strongly predicts LVMI in hypertension. The magnitude of this association is far greater than for resting hemodynamic load, suggesting that provoked testing captures important arterial properties that are not apparent at rest and is advantageous to assess dynamic arterial load in hypertension.

Preoperative Takotsubo cardiomyopathy identified in the operating room before induction of anesthesia.

We present a case of Takotsubo cardiomyopathy recognized in a patient just before induction of anesthesia. The patient's anxiety about surgery could have been an inciting factor. As the patient's surgery was cancelled and rescheduled for a later date, treatment and strategies to prevent recurrence of the syndrome are discussed.

Left ventricular assist devices and other devices for end-stage heart failure: utility of echocardiography.

The burgeoning ranks of patients with heart failure, the limited number of organs available for heart transplant, and technological improvements have made ventricular assist devices (VADs) important therapeutic options for patients with acute and chronic cardiac decompensation. The increased use of VADs is paralleled by an increased use of transthoracic and transesophageal echocardiography to 1) assist in the selection of patients for VAD therapy and VADs to meet patient needs; 2) identify important anatomic considerations prior to implant; 3) guide placement of VADs; 4) diagnose the etiology of VAD dysfunction; and 5) guide the weaning from VAD support and the optimization of VAD device settings. This review discusses types of VADs and the uses of echocardiography in the care of VAD patients.