Left Ventricular Pre-ejection Time Research Articles

Time-series NARX feedback neural network for forecasting impedance cardiography ICG missing points: a predictive model.

One of the crucial steps in assessing hemodynamic parameters using impedance cardiography (ICG) is the detection of the characteristic points in the dZ/dt ICG complex, especially the X point. The most often estimated parameters from the ICG complex are stroke volume and cardiac output, for which is required the left ventricular pre-ejection time. Unfortunately, for beat-to-beat calculations, the accuracy of detection is affected by the variability of the ICG complex subtypes. Thus, in this work, we aim to create a predictive model that can predict the missing points and decrease the previous work percentages of missing points to support the detection of ICG characteristic points and the extraction of hemodynamic parameters according to several existing subtypes. Thus, a time-series non-linear autoregressive model with exogenous inputs (NARX) feedback neural network approach was implemented to forecast the missing ICG points according to the different existing subtypes. The NARX was trained on two different datasets with an open-loop mode to ensure that the network is fed with correct feedback inputs. Once the training is satisfactory, the loop can be closed for multi-step prediction tests and simulation. The results show that we can predict the missing characteristic points in all the complexes with a success rate ranging between 75% and 88% in the evaluated datasets. Previously, without the NARX predictive model, the successful detection rate was 21%-30% for the same datasets. Thus, this work indicates a promising method and an accuracy increase in the detection of X, Y, O, and Z points for both datasets.

Systolic time intervals and its relation to intraventricular dyssynchrony of the left ventricle in patients with dilated cardiomyopathy

Aim To assess the value of systolic time intervals [as simple echocardiographic parameters of left ventricle (LV) systolic performance] and its relation to intraventricular dyssynchrony (by speckle tracking) of the LV in patients with dilated cardiomyopathy. Patients and methods All the studied individuals were subjected to ECG and transthoracic echocardiography to measure LV dimensions and systolic function by conventional and speckle-tracking echo. Left ventricular pre-ejection time (LVPET), left ventricular ejection time (LVET), and the ratio of LVPET to LVET were also measured (LVPET/LVET). Two-dimensional strain to measure time to peak negative strain value of the LV segments was averaged to calculate TPS-SD. Results The enrolled population were 153 cases, divided into 123 patients and 30 normal individuals. There was a significant lower LV global longitudinal strain % in the patient group. Moreover, insignificant shorter LVET was seen in the patients. LVET had an inversely significant correlation with QRS duration and dyssynchrony index. The LVPET and PET/LVET ratio had a significant linear correlation with QRS duration and dyssynchrony index measured by two-dimensional strain (r=0.4, P<0.01). Conclusion Systolic time interval can be easily and accurately measured in patients with DCM and may be considered as an indicator for presence of LV intraventricular dyssynchrony.

Reduction of QRS amplitude correlates with decrease in left-ventricular pre-ejection time after cardiac resynchronisation therapy

Left ventricular pre-ejection time (LVPET) is associated with myocardial efficiency. LVPET increases in patients with heart failure and decreases after cardiac resynchronisation therapy (CRT) with variation according to pacing site. The objective of this study was to evaluate the relationship between electrocardiogram (ECG) parameters and LVPET in patients with CRT. It was an observational, prospective, and monocentric study. From May 2017 to October 2017, all patients who underwent CRT with left quadripolar lead in Rouen University Hospital were included. LVPET was evaluated by echocardiography and defined as the time between the beginning of the QRS and the beginning of pulsed Doppler signal positioned in left ventricular outflow tract in apical view. The following parameters on 12-leads ECG were assessed: QRS width in V3, sum of QRS amplitude in all lead. Measures were performed during bi-ventricular pacing (at each pacing electrode of the quadripolar lead called D1, M2, M3, P4, for distal to proximal ones), left-ventricular pacing alone, right-ventricular pacing alone, and spontaneous rhythm. Partial correlation test was used. Seventeen patients were included. In each patient, LVPET was correlated with QRS width ( P = 0.02, R = 0.194) and QRS amplitude ( P < 0.001, R = 0.427) ( Fig. 1 ). It was observed that the lower the LVPET, the lower the QRS amplitude and the narrower the QRS width. In each patient, mean variation of QRS width was equal to 64.7 ± 29.4%, mean variation of LVPET was equal to 37.1 ± 16.4% and mean variation of QRS amplitude was equal to 53.2 ± 27.4%. QRS width, but also QRS amplitude varies according to the pacing site after CRT and are correlated with left ventricular pre-ejection time. These ECG parameters could be helpful to optimize CRT.

Relationship between left ventricular pre-ejection time and ECG parameters after cardiac resynchronisation therapy

Left ventricular pre-ejection time (LVPET) is associated with myocardial efficiency. LVPET increases in patients with heart failure and decreases after cardiac resynchronisation therapy (CRT) with variation according to pacing site. The objective of this study was to evaluate the relationship between electrocardiogram (ECG) parameters and LVPET in patients with CRT. It was an observational, prospective, and monocentric study. From May 2017 to October 2017, all patients who underwent CRT with left quadripolar lead in Rouen University Hospital were included. LVPET was evaluated by echocardiography and defined as the time between the beginning of the QRS and the beginning of pulsed doppler signal positioned in left ventricular outflow tract in apical view. The following parameters on 12-leads ECG were assessed: QRS width in V3, sum of QRS amplitude in all lead. Measures were performed during bi-ventricular pacing (at each pacing point of the quadripolar lead: D1, M2, M3, P4), left ventricular pacing, right ventricular pacing, and spontaneous rhythm. Partial correlation test was used. Seventeen patients were included. In each patient, LVPET was correlated with QRS width ( P = 0.02, R = 0.194) and QRS amplitude ( P < 0.001, R = 0.427). The following relationship was observed: the lower is the LVPET, the lower is the QRS amplitude and the narrow is the QRS width. In each patient, mean variation of QRS width was equal to 64.7 ± 29.4%, mean variation of LVPET was equal to 37.1 ± 16.4% and mean variation of QRS amplitude was equal to 53.2 ± 27.4%. QRS width and QRS amplitude varies according to the pacing site after CRT and are correlated with left ventricular pre-ejection time. These ECG parameters could be helpful to optimize CRT.

Right carotid Doppler signal to optimize cardiac resynchronisation therapy implant procedure

Left-ventricular pre-ejection time (LVPET) varies according to cardiac homodynamic performance and is a predictive factor of clinical response to cardiac resynchronisation therapy (CRT) when > 140 ms. LVPET could then play a role in optimizing CRT implantation. However, its measurement requires the use of echocardiography in apical view, which is hardly compatible with device implantation environment. The objective of this study was to determine the relationship between LVPET measured conventionally from an apical view and time from beginning of QRS to beginning of Doppler signal flow (QWT) recorded at the right carotid. LVPET was measured using M5S probe and pulsed Doppler on aortic flow in apical view using echocardiography. QWT was measured using a Pedoff probe at the right carotid. These measurements were performed during spontaneous rhythm in all patients whenever possible and during left ventricular pacing, right ventricular pacing, and bi-ventricular pacing in CRT patients. LVPET and QWT were measured in 53 patients among whom 11 had a CRT device. A linear relationship between LVPET and QWT was observed (R Pearson coefficient = 0.926, P < 0.001) (Fig. 1). The intra-observatory and inter-observatory variabilities of QWT were 2.3% and 5.7% respectively. According to pacing setting in CRT patients, average variation of LVPET-Ped was equal to 23.3 ± 24.5%. Measurements of QWT from right carotid Doppler signal is an easy, reliable and reproducible method that can be used as a surrogate of LVPET. This could allow optimization of pacing sites location during CRT implant procedure.

Association of intraventricular mechanical dyssynchrony with response to cardiac resynchronization therapy in heart failure patients with a narrow QRS complex

AimsCurrent criteria for cardiac resynchronization therapy (CRT) are restricted to patients with a wide QRS complex (>120 ms). Overall, only 30% of heart failure patients demonstrate a wide QRS complex, leaving the majority of heart failure patients without this treatment option. However, patients with a narrow QRS complex exhibit left ventricular (LV) mechanical dyssynchrony, as assessed with echocardiography. To further elucidate the possible beneficial effect of CRT in heart failure patients with a narrow QRS complex, this two-centre, non-randomized observational study focused on different echocardiographic parameters of LV mechanical dyssynchrony reflecting atrioventricular, interventricular and intraventricular dyssynchrony, and the response to CRT in these patients.Methods and resultsA total of 123 consecutive heart failure patients with a narrow QRS complex (<120 ms) undergoing CRT was included at two centres. Several widely accepted measures of mechanical dyssynchrony were evaluated: LV filling ratio (LVFT/RR), LV pre-ejection time (LPEI), interventricular mechanical dyssynchrony (IVMD), opposing wall delay (OWD), and anteroseptal posterior wall delay with speckle tracking (ASPWD). Response to CRT was defined as a reduction ≥15% in left ventricular end-systolic volume at 6 months follow-up. Measures of dyssynchrony can frequently be observed in patients with a narrow QRS complex. Nonetheless, for LVFT/RR, LPEI, and IVMD, presence of predefined significant dyssynchrony is <20%. Significant intraventricular dyssynchrony is more widely observed in these patients. With receiver operator characteristic curve analyses, both OWD and ASPWD demonstrated usefulness in predicting response to CRT in narrow QRS patients with a cut-off value of 75 and 107 ms, respectively.ConclusionMechanical dyssynchrony can be widely observed in heart failure patients with a narrow QRS complex. In particular, intraventricular measures of mechanical dyssynchrony may be useful in predicting LV reverse remodelling at 6 months follow-up in heart failure patients with a narrow QRS complex, but with more stringent cut-off values than currently used in ‘wide’ QRS patients.

Interventricular mechanical dyssynchrony: A novel marker of cardiac events in Brugada syndrome

Risk stratification in Brugada syndrome is controversial, especially in asymptomatic individuals. The purpose of this study was to evaluate tissue Doppler echocardiography in risk stratification of Brugada syndrome. Patients with Brugada ECG pattern were enrolled in the study. Left ventricular (LV) preejection period was defined as the time interval between onset of the QRS complex and onset of LV lateral wall systolic wave. Right ventricular (RV) preejection period was defined as the time interval between onset of the QRS complex and onset of RV lateral wall systolic wave. Delay in onset of contraction between RV and LV was defined as RV preejection time - LV preejection time [PET((RV-LV))]. Type 1, 2, and 3 Brugada ECG pattern was found in 30, 56, and 31 patients, respectively. PET((RV-LV)) was significantly greater in type 1 Brugada patients (39.2 +/- 3.2 ms) compared with type 2 (5 +/- 0.3 ms) and 3 (5 +/- 0.4 ms) Brugada patients as well as controls (4.6 +/- 0.3 ms, P <.01 for all comparisons). Among type 1 Brugada patients, PET((RV-LV)) was significantly greater in patients who had previous cardiac events compared with asymptomatic subjects (48.2 +/- 4.3 ms vs 29.5 +/- 3.6 ms, P <.05). In the presence of type 1 Brugada ECG pattern, PET((RV-LV)) > or =40 ms identifies patients likely to have cardiac events, with 85.7% sensitivity and 93.7% specificity. PET((RV-LV)) is an important risk indicator for Brugada syndrome.

The effects of donor-recipient size disparity in infant and pediatric heart transplantation

To determine the effect of heart donor and recipient size mismatches in infant and pediatric heart transplantation, we studied all 69 patients (age 1 day to 11 years) having 71 orthotopic heart transplants from 1985 to 1989. Patients were divided into three groups based on donor to recipient weight ratios. Group I comprised 13 heart transplants with a donor to recipient weight ratio less than 0.95 (mean 0.81, range 0.48 to 0.94); group II comprised 29 heart transplants with a weight ratio between 0.95 and 1.60 (mean 1.28); and group III had 27 heart transplants with weight ratios greater than 1.60 (mean 2.2, range 1.61 to 3.09). All chests were closed primarily. The cardiothoracic ratio by chest radiography was significantly larger in group III (p = 0.0002); 75% of group III patients had periods of lobar or complete lung collapse by chest radiography compared with 28% of group II and 19% of group I patients (p < 0.05). Despite this, there was no difference in the number of days of ventilator support for any group (p = 0.92). There was no difference in graft ischemic time or inotropic drug use among groups, nor were differences found in the cardiac systolic function parameters of left ventricular preejection time (p = 0.975), left ventricular ejection time (p = 0.975), left ventricular fiber shortening (p = 0.97), and left ventricular fractional shortening (p = 0.596). Thus despite a high incidence of transient lobar or complete lung collapse in high donor to recipient weight ratio transplants, large donor heart size produces very little clinical impairment in recipient lung function. Size mismatches do not influence cardiac systolic function. Overall, large size mismatches appear to be very well tolerated in infant and pediatric heart transplantation.

Detection and prevention of cardiac dysfunction during aortic surgery

Anesthesia and aortic occlusion and release all can adversely affect cardiac function during aortic reconstruction. To minimize these effects we developed on-line computerized monitoring techniques to measure systolic time intervals (STI) and compared these data with results of cardiac output, and in nine patients with pulmonary artery pressures obtained by Swan-Ganz catheters. In 35 patients, left ventricular preejection time (PEP), left ventricular ejection time (LVET), and PEP/LVET were displayed continuously in the operating room. Paired cardiac outputs, determined by dye dilution ( 26 35 ) or thermodilution ( 9 35 ) provided cardiac index and systemic vascular resistance. Pulmonary artery diastolic pressure (PADP) was taken for the assessment of preload. Heart rate and mean arterial pressure were recorded using radial artery cannulas. Characteristic changes were noted and compared during anesthesia and clamping and release of aortic occlusion. Changes in LVET were most notable with highly significant increases during aortic crossclamping. This overall effect occurred frequently in patients with EKG evidence of prior myocardial infarction ( 24 25 ). In 11 patients without previous myocardial infarction, LVET increased only once during aortic crossclamping. STI were clearly most sensitive for titrating both anesthetic and vasoactive drugs to minimize cardiac depression. In contrast, pulmonary artery diastolic pressures appeared more specific for alterations in blood and fluid balance. While changes in PADP were often inconclusive, changes in STI made possible rapid detection of adverse effects of anesthesia, crossclamping, and unclamping upon cardiac function. The immediate detection and treatment of changes in left ventricular function add an important safety factor in minimizing cardiac mortality of aortic surgery.