Left Ventricular Pre-ejection Period Research Articles

Traditional Criteria of Mechanical and Electrical Dyssynchrony as a Predictor of Super-Response in Patients with Cardiac Resynchronization Therapy

Aim: To evaluate clinical and morpho-functional predictors of super-response to cardiac resynchronization therapy (CRT) in patients with heart failure and reduced ejection fraction (HFrEF) in the short-term period after implantation.Material and Methods. The study enrolled 86 patients (88.4% men, 54.0 ± 8.9 years mean age, New York Heart Association (NYHA) class II–IV). Patients were examined at baseline and in dynamics (mean follow-up was 10.6 ± 3.6 months). According to the change in left ventricular (LV) end-systolic volume (ESV) patients were divided into two groups: Group I (n = 19) with a decrease in LV ESV ≥ 30% (super-responders (SR) and Group II (n = 67) – decrease in LV ESV < 30% (non-super-responders (non-SR). Parameters of mechanical dyssynchrony (MD) were assessed in the two groups including LV pre-ejection period, interventricular mechanical delay (IVMD), intraventricular delay (IVD).Results. At baseline, traditional parameters of MD were higher in SR: LV pre-ejection period (156.8 ± 35.4 ms vs 135.0 ± 35.6 ms; p = 0.021) and IVMD (73.0 [43.0; 108.0] ms vs 47.0 [19.5; 70.0] ms; p = 0.017). Logistic regression results showed that female gender (HR 7.048; 95% CI 1.496–33.206; p = 0.014) and QRS width (HR 1.017; 95% CI 1.000–1.034; p = 0.048) had an independent association with super-response.Conclusion. In patients with HFrEF, more severe mechanical and electrical dyssynchrony is associated with super-response to CRT in a short-term follow-up period.

Differences in pulse rate variability with measurement site

BackgroundRecently, attempts have been made to use the pulse rate variability (PRV) as a surrogate for heart rate variability (HRV). PRV, however, may be caused by the fluctuations of left ventricular pre-ejection period and pulse transit time besides HRV. We examined whether PRV differs not only from HRV but also depending on the measurement site.ResultsIn five healthy subjects, pulse waves were measured simultaneously on both wrists and both forearms together with single-lead electrocardiogram (ECG) in the supine and sitting positions. Although average pulse interval showed no significant difference from average R-R interval in either positions, PRV showed greater power for the low-frequency (LF) and high-frequency (HF) components and lower LF/HF than HRV. The deviations of PRV from HRV in the supine and sitting positions were 13.2% and 7.9% for LF power, 24.5% and 18.3% for HF power, and − 15.0% and − 30.2% for LF/HF, respectively. While the average pulse interval showed 0.8% and 0.5% inter-site variations among the four sites in the supine and sitting positions, respectively, the inter-site variations in PRV were 4.0% and 3.6% for LF power, 3.8% and 4.7% for HF power, and 18.0% and 17.5% for LF/HF, respectively.ConclusionsThese suggest that PRV shows not only systemic differences from HRV but also considerable inter-site variations.

Echocardiographic markers of dyssynchrony as predictors of super-response to cardiac resynchronisation therapy \u2013 a pilot study

BackgroundSome patients with congestive heart failure have greater improvement of cardiac remodelling after cardiac resynchronisation therapy (CRT) and they are identified as super-responders (SRs). It remains unclear if echocardiographic markers of dyssynchrony could accuratelly predict super-response to CRT. The aim of this study is to evaluate potential echocardiographic predictors associated with super-response to CRT.MethodsFifthy nine CRT patients (mean age 52.9 ± 9.0 years, 88% men) with congestive heart failure (54% ischaemic and 46% non-ischaemic aetiology) II-IV NYHA functional class were enrolled. To assess mechanical dyssynchrony we evaluated interventricular mechanical delay, the maximum delay between peak systolic velocities of the septal and posterior walls of left ventricle, duration of left ventricular pre-ejection period (LVPEP), left ventricular and interventricular dyssynchrony by tissue Doppler imaging and systolic dyssynchrony index by 3D echocardiography. After six months the patients were assessed for response and classified as SRs (reduction in left ventricular end-systolic volume (LVESV) ≥30%, n = 20) and non-SRs (reduction in LVESV < 30%, n = 39) and baseline data were analyzed to identify the predictors.ResultsBoth groups demonstrated significant improvement in NYHA functional class, increase in left ventricular ejection fraction and reduction in LVESV. All parameters of mechanical dyssynchrony at baseline were significantly higher in SR group. Multiple logistic regression analysis showed that LVPEP (HR 1.031; 95% CI 1.007–1.055; p = 0.011) was an independent predictor for CRT super-response. In ROC curve analysis LVPEP with a cut-off value of 147 ms demonstrated 73.7% sensitivity and 75% specificity (AUC = 0.753; p = 0.002) for the prediction of super-response to CRT.ConclusionGreater mechanical dyssynchrony is associated with super-response to CRT in patients with congestive heart failure. It is probable that an LVPEP > 147 ms can be used as independent predictor of super-response.

Prediction of superresponse to cardiac resynchronisation therapy in patients with congestive heart failure

The aim.To evaluate clinical, morphological, functional features and mortality in patients with congestive heart failure (CHF) and super-response to cardiac resynchronization therapy (CRT), to assess presence and severity of mechanical dyssynchrony in patients with super-response and to find potential predictors of super-response to CRT.Methods.106 CRT patients (mean age 54.7 ± 9.9 years; 83% men) with CHF II–IV NYHA functional class were enrolled for the study. At baseline and each 6 months after implantation clinical, electrocardiographic and echocardiographic parameters, NT-proBNP level were evaluated. According to the best decrease of left ventricular endsystolic volume (LVESV) (mean follow-up period 34.9 ± 16.1 months) patients were classified as super-responders (SR) (n = 45; reduction in LVESV ≥30%) and non-SR (n = 61; reduction in LVESV &lt;30%).Results.At baseline groups were matched for main clinical characteristics. The proportion of patients with atrial fibrillation, width of the QRS complex, and the presence of left bundle-branch block were comparable between groups. Parameters of mechanical dyssynchrony were higher in SR: left ventricular pre-ejection period (LVPEP) (153.0 ± 35.9 ms vs 126.6 ± 35.1 ms; р = 0.005), interventricular mechanical delay (55.9 ± 30.8 ms vs 40.4 ± 29.9 ms; р = 0.049), systolic dyssynchrony index (9.6 ± 2.6% vs 7.2 ± 0.7%; р = 0.048). NT-proBNP level was lower in SR. SR demonstrated better dynamics of LVESV, LVEF. At baseline and in dynamics level of NT-proBNP was lower in SR. In both groups NT-proBNP decreased significantly, but reduction of NT-proBNP was more evident in SR. The survival rates were 100%in SR and 83.6% in non-SR (log rank test p = 0.002).According to multiple logistic regression analysis LVPEP (HR 1.025; 95% CI 1.006–1.044; p = 0.010) and baseline NT-proBNP level (HR 0.624; 95% CI 0.426–0.913; p = 0.015) were independent predictors for CRT super-response with sensitivity 71.9% and specificity 78.6%.Conclusion.In patients with CHF greater mechanical dyssynchrony and lower level of NT-proBNP are associated with CRT super-response. SR demonstrate better survival and better dynamics of functional parameters in long-term period. LVPEP and NT-proBNP level can be used as independent predictors of CRT super-response.

Right Ventricular Apical Pacing (RVAP) vs. Right Ventricular Septal Pacing (RVSP): short and intermediate-term effect on echocardiographic indices, left ventricular function and clinical outcome

Introduction. Right ventricular apical pacing (RVAP) has a greater ‘desynchronizing effect’ than pacing from the interventricular septum (RVSP) and may translate into worse outcomes in the long run. The aim of the present study was to examine the short- and intermediate-term effects of RVAP versus RVSP on echocardiographic features, left ventricular function, and clinical outcome. Materials and methods. 467 patients between August 2014 and March 2018 without structural heart disease were prospectively randomised to RVAP (N = 226) or RVSP (N = 241) and were studied at baseline, six months, and 12 months by echocardiography, biochemically [N-terminal pro-B-type natriuretic peptide (NT-proBNP)], and clinically [six-minute walk test (6MWT)]. Left ventricular 2D strain and tissue velocity images were analysed to measure 18-segment time-to-peak longitudinal systolic strain and 12-segment time-to-peak systolic tissue velocity. Intraventricular dyssynchrony was calculated using tissue Doppler velocity data by comparing the time to systolic peak velocity between segments in multiple apical views by their respective standard deviations. Interventricular dyssynchrony was measured as the temporal difference of left ventricular pre-ejection period and right ventricular pre-ejection period by pulse-wave Doppler images. All the analysis was carried out using statistical package for social service version 17.0 (SPSS Inc., Chicago, IL, USA). A p-value Results. The commonest indication for pacemaker implantation was atrioventricular block (N = 311, 66.6%), followed by sinus node dysfunction (N = 138, 29.5%) and chronic bifascicular and trifascicular block (N = 18, 3.9%), with all patients receiving a single chamber pacemaker (VVI: n = 107, 22.9% and VVIR: n = 360,77.1%). There were significant differences in NT-proBNP level (410 ± 254 pg/mL vs. 370 ± 168 pg/mL, p = 0.02), 6MWT (442 ± 19 m vs. 482 ± 21 m, p = 0.01), mean QRS duration (164 ± 8.3 ms vs. 148 ± 10.6 ms, p = 0.02), intraventricular dyssynchrony (septal to lateral wall delay: 88.6 ± 24.2 ms vs. 43.7 ± 11.2 ms, p = 0.04), interventricular dyssynchrony (31.2 ± 22.8 vs. 19.4 ± 11.2, 0 = 0.03), end diastolic volume (78.4 ± 15.6 mL vs. 72.8 ± 14.2 mL, p = 0.04), and end-systolic volume (30.2 ± 13.1 mL vs. 25.6 ± 11.7 mL, p = 0.05) at the end of 12 months between RVAP and RVSP respectively, though not significantly different at six months, favouring the RVS-paced group. However, no significant difference in ejection fraction (59 ± 5% vs. 61.5 ± 3.2%, p = 0.39) and New York Heart Association class (1.29 ± 0.3 vs. 1.28 ± 0.4, p = 0.3) at six and 12 months follow up were noted. Conclusion. Right ventricular septal pacing was associated with a better outcome in terms of echocardiographic indices, left ventricular function, and clinical outcome compared to patients with apical pacing over an intermediate-term follow up.

Estudio cuantitativo de la ecocardiografía equina

The authors carried out a study on differents echocardiographic values of the horse. They determi­ned the following parameters: Lefi Ventricular Diastolic Diameter (LVDD), Lefi Ventricular Systolic Diameter (LVSD), Diastolic Thickness of Interventricular Septum (DTIS), Systolic Thickness of Inter­ventricular Septum (STIS), Left Ventricular Diastolic Thickness of Free Wall (LVDTFW), Lefi Ventricu­lar Systolic Thickness of Free Wall (LVSTFW), Diastolic Diameter of Left Atrium (DDLA), Diastolic Diameter of Aortic Ring (DDAR), Diastolic Diameter of Valsalva Sinus (DDVS), Diastolic Diameter of Aortic Root (DDAR), Diastolic Area of Aortic Ring (DAAR), Diastolic Perimeter of Aortic Ring (DPAR), Left Ventricular Diastolic Volume (LVDV), Left Ventricular Systolic Volume (LVSV), Left Ventricular Ejec­tion Fraction (LVEF), Left Ventricular Fractional Shortening (LVFS), Velocity of Circumferencial Shor­tening (VCS), Left Ventricular Free Wall Fractional Thickening (LVFWFS), Fractional Thickening of Interventricular Septum (FTIS), E-point Septal Separation (EPSS), Normalized E-point Septal Separa­tion (EPSSn), Left Ventricular Pre-ejection Period (LVPEP), Left Ventricular Ejection Time (LVET), Total electromechanical Systole (TES) and the LVPEP/LVET ratio.Statistically we obtained the mean,-standard deviation, coefficient of variation, median, the maxi­mum and minimum values, first and third cuartil. Also the correlation between the EPSS and LVFS; EPSSn and LVFS; Systolic intervals and hearta e Systolic-intervals and body weight; ventricular dia­meters and body weight, ventricular volumes and body weight; parietal and septal thickness and bodyweight was also studied. Also, in the casas in which the correlation was significant the lineal regres­sion was studied.The obtained values of each one of the parameters studiéd are in the Tables 1 and II of the body of the article.

Modulation of plasma adrenomedullin by epinephrine infusion during head up tilt

We investigated whether head up tilt (HUT) with and without simultaneous epinephrine infusion modulate plasma adrenomedullin. We studied eight healthy male volunteers, using two 5 min 70° HUT trials: control (saline infusion) and intervention (epinephrine infusion, titrated to a dose which increased supine systolic pressure by 20% above resting values). Protocols were randomized and separated by 2 weeks. Cardiac function and systolic time intervals, recorded using a phonocardiograph microphone, included left ventricular ejection time (LVET), pre-ejection period (PEP), PEP/LVET and electromechanical systole (QS2). Compared to saline infusion, epinephrine increased supine adrenomedullin (3.2 ± 0.8 pmol/l, i.e., mean ± SEM, respectively), heart rate (HR) (+11.3 ± 2.6 bpm), systolic pressure (+18.4 ± 2.6 mmHg) but decreased supine LVET, LVET corrected for HR (LVETi) and QS2-time (all p = 0.004). Despite similar HUT induced thoracic fluid shifts, reflected by similar thoracic impedance changes, HUT-induced adrenomedullin increases were minimal in epinephrine-supplemented men in comparison to controls (+8% vs. 42%). During HUT, epinephrine infusion decreased only the LVET (p = 0.039). Our findings confirm that short-term HUT increases plasma adrenomedullin. They further suggest that with increased supine epinephrine levels (epinephrine infusion clamping systolic arterial pressure at 120% control level), supine cardiac performance rises to a level similar to that during HUT, while adrenomedullin is still elevated with HUT. This might be in accordance with a 'dampening' role of adrenomedullin during catecholaminergic cardiovascular stimulation. As epinephrine is used as a drug to treat cardiac arrest and ventricular arrhythmias, our results may have important clinical/emergency resuscitation applications.

Assessment of Left Ventricular Pre-Ejection Period in the Fetus Using Simultaneous Magnetocardiography and Echocardiography

Introduction: Fetal magnetocardiography (fMCG) is a promising new technique for assessing fetal rhythm; however, no prior studies have utilized fMCG to evaluate human fetal electromechanical physiology. Pre-ejection period (PEP) is an important measure of the electromechanical activation of the heart, and is altered by disease states and arrhythmias. Materials and Methods: A novel technique was used to assess fetal PEP and its relationship to other fetal systolic time intervals, RR interval, and gestational age (GA). 25 normal human fetuses between 19 and 38 weeks’ gestation were studied using simultaneous pulsed Doppler ultrasound and fMCG. Correlations among PEP, ejection time, QRS width and RR interval were assessed using linear regression. Results: Across all subjects, PEP was found to correlate with GA (R = 0.57, p < 0.0001), QRS width (R = 0.35, p = 0.026), and RR interval (R = 0.37, p = 0.018). In individual sessions, PEP negatively correlated beat-to-beat with the preceding RR interval. Conclusion: PEP exhibits developmental trends that provide a better understanding of the normal development of the human fetal heart.

WISE-2005: prolongation of left ventricular pre-ejection period with 56 days head-down bed rest in women

This study tested the hypothesis that prolonged physical deconditioning affects the coupling of left ventricular depolarization to its ejection (the pre-ejection period, PEPi) and that this effect is minimized by exercise countermeasures. Following assignment to non-exercise (Control) and exercise groups (Exercise), 14 females performed 56 days of continuous head-down tilt bed rest. Measurements of the electrocardiogram (ECG) and stroke volume (Doppler ultrasound) during supine rest were obtained at baseline prior to (Pre) and after (Post) the head-down tilt bed rest (HDBR) period. Compared with Pre, the PEPi was increased following head-down tilt bed rest (main effect, P < 0.005). This effect was most dominant in the Control group [Pre = 0.038 ± 0.06 s (s.d.) versus Post = 0.054 ± 0.011 s; P < 0.001]. In the Exercise group, PEPi was 0.032 ± 0.005 s Pre and 0.038 ± 0.018 s Post; P= 0.08. Neither the QRS interval nor cardiac afterload was modified by head-down tilt bed rest in Control or Exercise groups. Low-dose isoprenaline infusion reversed the head-down tilt bed rest-induced delay in the PEPi. These results suggest that head-down tilt bed rest leads to a delayed onset of systolic ejection following left ventricular depolarization in a manner that is affected little by the exercise countermeasure but is related to β-adrenergic pathways. The delayed onset of systole following head-down tilt bed rest appears to be related to mechanism(s) affecting contraction of the left ventricle rather than its depolarization.

Assessment of left ventricular size and function in horses using anatomical M-mode echocardiography

Objective To study the applicability of anatomical M-mode (AMM) for assessment of left ventricular (LV) size and function in horses, evaluate agreement with conventional M-mode (CMM), determine reliability, and establish reference intervals for AMM measurements. Animals 98 horses; 13.1 ± 5.6 years; 538 ± 78 kg. Methods Two-dimensional and M-mode recordings were analyzed retrospectively. Standard LV dimensions and indices of LV function, including time intervals, were measured in CMM and compared with AMM studies in long-axis (lx) and short-axis (sx) views. Results The percentages of measureable cycles were 99%, 97%, and 90% for routine LV studies in CMM sx, AMM sx, and AMM lx mode. For time intervals, ≥ 93% of cycles could be measured using AMM compared to a maximum of 77% using CMM. AMM sx measurements agreed well with CMM sx measurements for LV studies; the agreement of AMM lx with CMM sx was markedly lower. The LV ejection time and the duration of electromechanical systole, but not the LV pre-ejection period and the index of myocardial performance, showed fair agreement between methods. Intraobserver and interobserver measurement variabilities were low for most variables. Conclusions AMM can replace CMM for assessment of LV dimensions in horses, but is not recommended for measurement of time intervals.

Using a human cardiovascular-respiratory model to characterize cardiac tamponade and pulsus paradoxus

BackgroundCardiac tamponade is a condition whereby fluid accumulation in the pericardial sac surrounding the heart causes elevation and equilibration of pericardial and cardiac chamber pressures, reduced cardiac output, changes in hemodynamics, partial chamber collapse, pulsus paradoxus, and arterio-venous acid-base disparity. Our large-scale model of the human cardiovascular-respiratory system (H-CRS) is employed to study mechanisms underlying cardiac tamponade and pulsus paradoxus. The model integrates hemodynamics, whole-body gas exchange, and autonomic nervous system control to simulate pressure, volume, and blood flow.MethodsWe integrate a new pericardial model into our previously developed H-CRS model based on a fit to patient pressure data. Virtual experiments are designed to simulate pericardial effusion and study mechanisms of pulsus paradoxus, focusing particularly on the role of the interventricular septum. Model differential equations programmed in C are solved using a 5th-order Runge-Kutta numerical integration scheme. MATLAB is employed for waveform analysis.ResultsThe H-CRS model simulates hemodynamic and respiratory changes associated with tamponade clinically. Our model predicts effects of effusion-generated pericardial constraint on chamber and septal mechanics, such as altered right atrial filling, delayed leftward septal motion, and prolonged left ventricular pre-ejection period, causing atrioventricular interaction and ventricular desynchronization. We demonstrate pericardial constraint to markedly accentuate normal ventricular interactions associated with respiratory effort, which we show to be the distinct mechanisms of pulsus paradoxus, namely, series and parallel ventricular interaction. Series ventricular interaction represents respiratory variation in right ventricular stroke volume carried over to the left ventricle via the pulmonary vasculature, whereas parallel interaction (via the septum and pericardium) is a result of competition for fixed filling space. We find that simulating active septal contraction is important in modeling ventricular interaction. The model predicts increased arterio-venous CO2 due to hypoperfusion, and we explore implications of respiratory pattern in tamponade.ConclusionOur modeling study of cardiac tamponade dissects the roles played by septal motion, atrioventricular and right-left ventricular interactions, pulmonary blood pooling, and the depth of respiration. The study fully describes the physiological basis of pulsus paradoxus. Our detailed analysis provides biophysically-based insights helpful for future experimental and clinical study of cardiac tamponade and related pericardial diseases.

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.

Cardiovascular impact of dobutamine in neonates with myocardial dysfunction

Objective To study effects of dobutamine on cardiac functional parameters, cerebral, mesenteric and renal blood flow in preterm neonates with myocardial dysfunction. Study design Prospective evaluation of Doppler sonographically measured left ventricular systolic time intervals, stroke volume (SV), cardiac output (CO), and blood flow parameters of anterior cerebral artery (ACA), superior mesenteric artery (SMA) and renal arteries (RA), before, after 20 min and 8–10 h of dobutamine treatment in 20 neonates (gestational age 29.6 ± 4.4 weeks, birth weight 1450 ± 609 g and postnatal age 2 ± 2.1 days). Dobutamine was given in a mean dosage of 9.1 ± 1.1 μg/kg. Results After 20 min SV increased from 1.71 ± 0.5 ml to 2.12 + 0.57 ml/kg, CO from 223 ± 76 to 290 ml/kg/min. A shortening of left ventricular pre ejection period from 86 ± 12 to 66 ± 13 ms and of the ratio of pre-ejection period/ejection time from 0.52 ± 0.12 to 0.40 ± 0.11 were observed. Blood flow velocities of ACA increased after 8–10 h: peak systolic flow velocity (PSV) from 19.0 ± 6 to 29.6 ± 7.1 ms, end diastolic velocity (EDV) from 2.9 ± 2.6 to 12.7 ± 11.3 ms. PSV of SMA increased from 32.5 ± 4.7 to 49.7 ± 7.8 ms after 8–10 h, EDV from 8.9 ± 8 ms to 20.6 ± 6.1 ms. PSV of RA increased from 18.2 ± 6.1 ms to 39.9 ± 4.8 ms, EDV from 2.2 ± 1.2 to 8.2 ± 2.1 ms after 8–10 h. The pulsatility indices decreased significantly after 8–10 h: ACA from 2.3 ± 0.6 to 1.4 ± 0.5, SMA from 1.7 to 1.2 and RA from 2.57 to 1.57. Conclusion Dobutamine improves the cardiac functional parameters already after 20 min and has an influence on the blood flow parameters of ACA, SMA and RA 8–10 h after administration in neonates with myocardial dysfunction.

307 Disturbed Cardiac Functional Parameters and Blood Flow Parameters of Peripheral Arteries in Premature Sga Neonates

Top of pageAbstract Problem: Small for gestational age preterm neonates (SGA) are at higher risk for early postnatal morbidity and cardiovascular and metabolic diseases in later childhood. The aim of the prospective study was to determine the cardiac adaptation and the organ blood flow in growth retarded neonates after intrauterine hemodynamic disturbances in comparison to appropriate for gestational age preterm infants (AGA). Patients and methods: 25 AGA neonates (29.1 ± 1.4 wks, 1420 ± 243 g) and 25 small for gestational age neonates (30.1 ± 1.2 wks, 985 ± 167 g) were examined during the first five days. By Doppler sonographic measurements the cardiac left ventricular systolic time intervals, peak systolic velocities, end diastolic velocities and pulsatility indices of anterior cerebral artery (ACA), superior mesenteric artery (SMA) and renal artery (RA) were investigated. Results: Significantly increased left ventricular pre ejection period was observed in SGA neonates. Systolic peak velocities and end diastolic velocities of ACA, SMA and RA were significantly decreased in SGA neonates in relationship to AGA neonates. The pulsatility indices were significantly increased in SGA neonates during the first five days. Conclusions: Disturbed left ventricular time intervals were observed as a sign of myocardial dysfunction in SGA neonates. In relationship to the diminished myocardial contractility there were demonstrated pathologically diminished blood flow parameters of peripheral vessels and an increased pulsatility caused by a vasoconstriction in the regional vascular bed. For that reason it seems possible, that the disturbed intrauterine perfusion persists into the postnatal life and could cause later cardiac and metabolic problems.

Effects of changing heart rate on electrophysiological and hemodynamic function in the dog

Cardiovascular parameters were measured in dogs after RR interval was changed from 0.25 s to 1.2 s with atropine and graded doses of zatebradine, an I f-channel blocker. Left ventricular (LV) pre-ejection period (PEP), systemic vascular resistance, tau (an estimate of myocardial stiffness), PQ, QTc, dLVP/dt max and dLVP/dt min, aortic pressure, and right atrial pressure did not change when each parameter was plotted against RR interval (r 2's ≤ 0.5). LV end-diastolic pressure, stroke volume index, LV ejection time (ET), and QT all increased either linearly or curvilinearly as RR interval prolonged. Cardiac output index and PEP/ET decreased curvilinearly. When heart rate (HR) was fixed by pacing, and graded doses of zatebradine were given, changes in cardiovascular function were minimal. Thus zatebradine affects cardiovascular function principally by changing HR and not by affecting function directly. This study provides data on the effects of changing HR, alone, on cardiovascular parameters measured frequently during pharmacological and toxicological studies. It should prove useful when physiological variables, including HR, change, and there is need to know what change in HR, alone, contributes.

Left ventricular myocardial impairment in subclinical hypothyroidism assessed by a new ultrasound tool: pulsed tissue Doppler.

Pulsed tissue Doppler (TD) is a new ultrasound tool that allows quantification of myocardial regional wall motion. To investigate the cardiac effects of subclinical hypothyroidism (SH), the present study assessed left ventricular (LV) myocardial regional function in SH by pulsed TD. Twenty women with SH and 20 healthy women underwent standard Doppler echocardiograms and pulsed TD, placing a sample volume at the level of posterior septum and LV mitral annulus. Myocardial systolic and diastolic velocities and time intervals were determined for both levels. Doppler-echocardiographic and TD measurements were adjusted for body surface area and heart rate. Standard Doppler showed an increases in LV preejection period, preejection period/LV ejection time ratio, and isovolumic relaxation time (IVRT) in SH. By TD analysis, myocardial precontraction time (PCT(m)), PCT(m)/myocardial contraction time ratio, and myocardial relaxation time (RT(m)) were prolonged at the level of both posterior septum and mitral annulus in SH. In the whole population, IVRT, PCT(m), and RT(m) were negatively related to FT(4), whereas IVRT, PCT(m)/myocardial contraction time ratio, and RT(m) were positively correlated to TSH. In conclusion, this study underscores the usefulness of TD to detect cardiac functional abnormalities due to stable SH, mainly by changes in myocardial time intervals in several LV segments.

Modifications of cardiac function in cirrhotic patients treated with transjugular intrahepatic portosystemic shunt (TIPS)

OBJECTIVES: The implantation of a transjugular intrahepatic portosystemic shunt (TIPS) has been shown to exacerbate the hyperdynamic circulation and might induce a significant cardiac overload. We investigated cardiac function before and 1, 3, 6, and 12 months after the TIPS procedure in cirrhotic patients. METHODS: Eleven patients with nonalcoholic cirrhosis were evaluated. Cardiovascular parameters were assessed by two-dimensional Doppler echocardiography. RESULTS: After TIPS, the left ventricular diastolic diameter increased from 26.5 ± 1.8 mm (basal) to 30.0 ± 2.8 mm (6 months) ( p < 0.05), whereas the ejection fraction showed a slight increase (basal, 64.5 ± 3.3; 6 months, 68.1 ± 3.2). The left ventricular pre-ejection period and the isovolumetric relaxation time decreased transiently at 1 month ( p < 0.05). An increased velocity in all of the components of pulmonary venous flow (systolic, diastolic, and atrial) documented the accelerated fluxes induced by the procedure. The estimated pulmonary systolic arterial pressure also increased at 1 month (29.5 ± 1.4 vs 44.1 ± 1.4 mm Hg, p < 0.05). All of these modifications reverted after 6 months. CONCLUSIONS: Our study demonstrates that nonalcoholic cirrhotic patients, without cardiovascular pathologies, show transient modifications in cardiac dimension and function for 3–6 months after TIPS caused by the increased volume load shunted to the heart.

Left atrial systolic time interval in hyperthyroidism.

The author noninvasively examined effects of thyroid hormone on left atrial function by using the left atrial systolic time intervals (LASTI) with its parameters as left atrial ejection time (LAET), left atrial preejection period (LAPEP), and LAET/LAPEP, as measured by pulsed Doppler echocardiography. The hyperthyroid (HTH) and normal control (NC) groups consisted of 21 and 25 subjects, respectively. He also considered serum triiodothyronine (T3) concentrations, age, heart rate, systolic blood pressure, left ventricular preload, afterload, contractility, diastolic function, P wave duration, PR interval, and left ventricular preejection period (LVPEP) as factors that might influence LASTI. LAET, LAET/LAPEP, and LVPEP in the HTH group were significantly shorter than in the NC group. LAET showed no significance with serum T3 concentration, but did with LVPEP in partial correlation analysis. These results demonstrated that a short LAET in the hyperthyroid state is controlled by a rapid rise in the left ventricular pressure.

Temporal effects of an infusion of dobutamine hydrochloride in horses anesthetized with halothane

Abstract Objective To evaluate temporal hemodynamic effects of dobutamine in horses anesthetized with halothane. Animals 8 adult Thoroughbreds. Procedure Anesthesia was induced by IV administration of romifidine and ketamine and maintained using halothane in oxygen. After 60 minutes, dobutamine was administered IV for 60 minutes at 4 μg/kg of body weight/min. Measurements of left ventricular function were obtained by transesophageal echocardiography and cardiac catheterization. Results Mean, systolic, diastolic, aortic, pulmonary arterial, and left and right ventricular end-diastolic and systolic pressures, maximal rate of increase of intraventricular pressure (LVdp/dtmax), maximum acceleration (dv/dtmax) and velocity (Vmax) of aortic blood flow, cardiac output, and left ventricular velocity time integral were significantly increased, whereas left ventricular pre-ejection period and ejection time significantly decreased. Cardiac output, LVdp/dtmax, Vmax, and dv/dtmax increased throughout infusion. Heart rate was significantly less after 10 minutes and significantly greater at 60 minutes than before infusion. Supraventricular tachycardia developed in 2 horses. Cardiac output, LVdp/dtmax, Vmax, dv/dtmax, left ventricular and aortic systolic pressures, and mean aortic pressure had not returned to control values 30 minutes after infusion was discontinued. Conclusions At this dosage, dobutamine did not achieve peak effect on many hemodynamic variables within 40 minutes of commencing infusion, and effects of 60-minute infusion persisted after infusion was discontinued. Clinical Relevance Dobutamine has a hemodynamic profile suited to treatment of low cardiac output in anesthetized horses; however, sustained administration may be associated with supraventricular tachycardia and a protracted time to peak effect. (Am J Vet Res 1998;59:1027–1032)

Haemodynamic effects of a sixty minute infusion of dopamine hydrochloride in horses anaesthetised with halothane.

To describe the haemodynamic effects of a 60 min infusion of dopamine 4 microg/kg bwt/min during halothane anaesthesia, 7 mature Thoroughbred horses were studied. The infusion began 1 h after induction of anaesthesia by romifidine (100 microg/kg) and ketamine (2.2 mg/kg bwt). Throughout the period of dopamine infusion and for 30 min after its discontinuation, the horses were ventilated by intermittent positive pressure to maintain PaCO2 between 4.6-5.4 KPa. Inspired halothane concentration was adjusted to maintain an end tidal halothane concentration of 0.9%. Haemodynamic variables were measured using intracardiac strain gauge transducers sited in the left and right ventricle, aorta, and pulmonary artery. Left ventricular pressure was differentiated to obtain maximal rate of increase of intraventricular pressure (LVdp/dtmax). Transoesophageal Doppler echocardiography was performed to measure maximum aortic blood flow velocity (vmax) and acceleration (dv/dtmax), left ventricular velocity time integral (vTI) and cardiac output (CO), and left ventricular pre-ejection period (PEP) and ejection time (ET). Measurements were made during the 60 min infusion, and for 30 min after the infusion was discontinued. Infusion of dopamine 4 microg/kg/min significantly decreased mean aortic pressure, while left and right ventricular end-diastolic pressure and mean pulmonary artery pressure remained unchanged. There was a small, but significant, increase in heart rate during dopamine infusion. Maximum acceleration of aortic blood flow, CO and vTI were also significantly increased by dopamine infusion. Maximal rate of increase of intraventricular pressure (LVdp/dtmax) was significantly decreased 10 min after commencing infusion, but then returned to baseline for the remainder of the study. Left ventricular pre-ejection period (PEP) decreased during dopamine infusion whilst ejection time (ET) significantly increased. All measured variables except LVET had returned to baseline values within 30 min of discontinuing the infusion. This study demonstrated beneficial effects of dopamine infusion upon left ventricular systolic function. However, the therapeutic value of the drug is likely to be limited in clinical anaesthesia due to the simultaneous falls in arterial blood pressure which accompany its administration.