Diastolic Left Ventricle Research Articles

Disparate Patterns of Left Ventricular Mechanics Differentiate Constrictive Pericarditis From Restrictive Cardiomyopathy

The purpose of this study was to compare the longitudinal, circumferential, and radial mechanics of the left ventricle (LV) in patients with constrictive pericarditis (CP) and restrictive cardiomyopathy (RCM). Diastolic dysfunction in CP is related to epicardial tethering and pericardial constraint, whereas in RCM it is predominantly characterized by subendocardial dysfunction. Assessment of variations in longitudinal and circumferential deformation of LV might be useful to distinguish these 2 conditions. Longitudinal, radial, and circumferential mechanics of the LV were quantified by 2-dimensional speckle tracking of B-mode cardiac ultrasound images in 26 patients with CP, 19 patients with RCM, and 21 control subjects. In comparison with control subjects, patients with CP had significantly reduced circumferential strain (base; -16 +/- 6% vs. -9 +/- 6%; p < 0.016), torsion (3 +/- 1 degrees /cm vs. 1 +/- 1 degrees /cm; p < 0.016), and early diastolic apical untwisting velocities (E(r); 116 +/- 62 degrees /s vs. -36 +/- 50 degrees /s; p < 0.016), whereas longitudinal strains, displacement, and early diastolic velocities at the LV base (E(m)) were similar to control subjects. In contrast, patients with RCM showed significantly reduced longitudinal displacement (base; 14.7 +/- 2.5 cm vs. 9.8 +/- 2.8 cm; p < 0.016) and E(m) (-8.7 +/- 1.3 cm/s vs. -4.4 +/- 1.1 cm/s; p < 0.016), whereas circumferential strain and E(r) were similar to those of control subjects. For differentiation of CP from RCM, the area under the curve was significantly higher for E(m) in comparison with E(r) (0.97 vs. 0.76, respectively; p = 0.01). After pericardiectomy, there was a significant decrease in longitudinal early diastolic LV basal myocardial velocities (7.4 cm/s vs. 6.8 cm/s; p = 0.023). Circumferential strain, torsion, and E(r), however, remained unchanged. Deformation of the LV is constrained in the circumferential direction in CP and in the longitudinal direction in RCM. Subsequent early diastolic recoil of LV is also attenuated in each of the 2 directions, respectively, uniquely differentiating the abnormal diastolic restoration mechanics of the LV seen in CP and RCM.

RAMIPRIL EFFICACY IN PATIENTS WITH ARTERIAL HYPERTENSION AND ISCHEMIC HEART DISEASE

Aim. To study ramipril effect on parameters of ambulatory blood pressure (BP) monitoring, cardio-vascular remodeling parameters in patients with arterial hypertension (HT) and ischemic heart disease (IHD). Material and methods. 40 patients with HT (stage 1-2) combined with IHD (functional class 1-2) were included in the study. All patients were randomized in 2 groups. Patients of the 1st group received basic therapy with aspirin, statin and ß-blocker. Patients of the 2nd group received the same therapy as well as ACE inhibitor ramipril (Hartil, EGIS). Changes in clinical status, daily BP profile, cardio-vascular remodeling parameters were evaluated. Results. After 12 week treatment clinical improvement was revealed in the both groups of the patients. Ramipril contributed additional pulse BP and BP loading reduction, regression of left ventricular hypertrophy, improvement of systolic and diastolic left ventricle function, increase in brachial artery diameter. Conclusion. Ramipril inclusion in the basic therapy of patients with HT and IHD increases in efficacy of antihypertensive treatment and improves structural and functional conditions of heart and vessels.

Diastolic function left ventricle in a debut of revealing of hypertonic illness at young age

The purpose: To estimate diastolic function left ventricle at persons of young age with recently revealed arterial hypertension and to reveal early attributes of its infringement. Materials and methods: On device LOGIQ 500 method Doppler echocardiography studies diastolic function left ventricle at 34 patients of young age with prescription of revealing arterial hypertension no more than 3 years and practically healthy 48 persons. Results: At an arterial hypertension already in a debut of revealing of disease change of some Doppler echocardiography parameters diastolic fillings left ventricle takes place: decrease in high-speed parameters early diastolic fillings and increase in peak speed and fraction of late filling left ventricle, that reflects difficulty of filling left ventricle and increased hemodinamic loading on the left auricle. The conclusion: Changes of speeds diastolic fillings left ventricle reflects its structurally functional remodeling and can be used as criterion of diagnostics of defeat of heart at arterial hypertension

Correlation of the myocardial performance index with plasma B-type natriuretic peptide levels in patients with mitral regurgitation

The Myocardial performance index (MPI) is an echocardiographic index of combined systolic and diastolic function, calculated as isovolumetric relaxation time plus isovolumetric contraction time divided by ejection time. The aim of this study was to define the correlation of the MPI with plasma B-type natriuretic peptide (BNP) levels and echocardiographic parameters in patients with chronic mitral regurgitation (MR). About 33 patients with at least moderate MR of organic etiology were enrolled to the study. All patients undergone complete 2D and Doppler echocardiography. Plasma BNP levels were studied. BNP levels in NYHA classes I-III were 9.3 +/- 2.2 pg/ml, 61.3 +/- 12.2 pg/ml, and 199.6 +/- 55.2 pg/ml, respectively (I vs. II P < 0.001, I vs. III P < 0.001 and II vs. III P = 0.004). Myocardial performance index were 0.42 +/- 0.02, 0.49 +/- 0.02, and 0.52 +/- 0.03 in MR patients with NYHA I-III, respectively. MPI was significantly higher in patients with NYHA class III compared to NYHA I (P = 0.001) and NYHA II (P = 0.005). There were no correlations between MPI and left atrial diameter, MR jet area, MR index and systolic pulmonary artery pressure whereas left ventricle (LV) end-systolic volume (r = 0.38), LV end-diastolic volume (LVDV) (r = 0.40), LV ejection fraction (r = -0.59), NYHA class (r = 0.51) and plasma BNP levels (r = 0.67) were strongly correlated. Only independent variable affecting MPI was plasma BNP level (odds ratio [CI]: 2.18[0.002-0.098], P = 0.041). MPI is a powerful index in assessing the severity of left ventricular function and symptom severity in patients with MR. Plasma BNP is an independent predictor of MPI where both parameters assess combined systolic and diastolic LV function, effectively.

Cardiac Resynchronization Improves Coronary Blood Flow

Asynchronous ventricular activation, induced by left bundle branch block, is known to have deleterious effects on the systolic and diastolic functions of the left ventricle (LV). Cardiac resynchronization therapy (CRT) has been proposed as a complementary method to improve the LV systolic performance by restoring the synchronized contraction patterns in patients with advanced heart failure and left bundle branch block. However, the effect of CRT on myocardial blood flow is not well established. In the present study, we therefore examined the coronary blood flow in 20 patients with idiopathic dilated cardiomyopathy, implanted with a biventricular pacemaker according to the established CRT criteria. Color Doppler settings were adjusted for the optimal coronary flow imaging, and coronary flow velocities were obtained in all patients. Typical diastolic predominant phasic Doppler spectrum of the distal left anterior descending coronary artery (LAD) was recorded. Conventional echocardiographic variables, peak values of the diastolic and systolic LAD velocities, and the velocity time integrals were measured for three or five consecutive beats during CRT with pacemaker on and off. Successful CRT with biventricular pacing increased coronary blood flow velocities of the distal LAD in addition to its well-known benefits on the systolic and diastolic LV performance in patients with significant dyssynchrony. CRT decreased duration of mitral regurgitation and increased diastolic filling time. Peak diastolic velocities and velocity time integral of the distal LAD were increased significantly. In conclusion, successful CRT with biventricular pacing improves coronary blood flow velocities of the distal LAD.

P349 The effect of CPAP therapy in the patients with heart failure after myocardial infarction

Objectives: To evaluate therapeutic effect of CPAP therapy in patients presenting the association of severe sleep apnea syndrome and heart failure following myocardial infarction (MI). Materials and methods: Twelve patients with heart failure (III functional class) after myocardial infarction were examined. Echocardiography, cardiorespiratory monitoring (CRM) and 6 min walking test were evaluated for all patients. All patients received standard therapy with ACE-inhibitors, blockers, diuretics, antiaggregants and statins. Six patients were treated with CPAP therapy, the other six patients formed the control group. Results: At the beginning of the study all patients displayed the equal contractile left ventricular ejection fraction (EF), diastolic left ventricle volume (LVd), apnea– hypopnea index (AHI), and tolerance to physical exercises. By the 11th month of the study the patients of the CPAP group had showed the increased contractile ability of the left ventricle in comparison with the control (EF 49.6 ± 9.0% and 56.6 ± 9.9%, accordingly) and significant decrease in LVd (50.1 ± 1.5 mm and 55.1 ± 2.2 mm in CPAP and control groups correspondingly). Moreover, control patients displayed lower tolerance to physical exercises. Conclusion: The correction of impaired breathing in patients with cardiac insufficiency at the background of myocardial infarction history, significantly improved left ventricle function and patients’ tolerance to physical exercises, improving thus their life quality.

P6-90: Effect of ventricular pacing on cardiac apex rotation assessed by an implanted coriolis force sensor

Cardiac Apex Rotation (CAR) has been shown to provide a sensitive index of both systolic and diastolic Left Ventricle (LV) dynamics. As an alternative to sophisticated techniques (i.e. radiopacque markers and tagged magnetic resonance) not suitable for a chronic monitoring of LV dynamics we recently proposed the use of an implanted gyroscopic sensor (Gyro) based on Coriolis force to quantify CAR. The purpose of this study was to evaluate in a sheep model the effects of asynchronous contraction and relaxation resulting from ventricular pacing on the rotational mechanics of LV over the full cycle.

Hemodynamic Consequences of a Swinging, Infarcted Ventricular Septum

Noonan syndrome presents with dysmorphic facial features, short stature, and cardiac abnormalities (most commonly pulmonic stenosis and hypertrophic cardiomyopathy). This report describes a rare case accompanied by a secundum atrial septal defect (ASD) and a ventricular septal aneurysm causing right ventricular (RV) pressure gradient. A 29-year-old mentally retarded man was admitted to hospital with exertional dyspnea. His somatic features included short stature (148 cm), hypertelorism, a shield chest, and thoracic scoliosis. Echocardiogram showed a secundum ASD with bidirectional shunting and a ventricular septum bulging toward the left ventricle in diastole, and then toward the RV in systole causing obliteration of the RV. The peak pressure gradient measured across the RV outflow by continuous wave Doppler was 30 mmHg. Cardiac catheterization revealed an elevated RV pressure without pulmonary hypertension and confirmed the pressure gradient. Right ventriculography revealed the septal excursion toward the RV in systole, leaving only a small residual cavity in the inflow and outflow regions of the RV. The ASD was closed with an autologous pericardial patch. A thin, fibrous portion of the ventricular septum was resected and replaced with a Dacron patch. From the histological examination, the RV cavity obliteration turned out to be produced by the excursion of the infarcted ventricular septum.

New reference values for echocardiographic dimensions of healthy Dutch children

To renew the echocardiographic reference values of heart dimensions in healthy children. Group 1 consisted of 587 children, of which 361 boys and 226 girls, age from birth to 18 years, body weight over 2500 g, who visited the Pediatric Cardiology outclinic during the period January 2000 till March 2004. All included children were diagnosed as normal, or as having innocent heart murmur. The second group was taken from an earlier study and comprised 160 children (77 boys and 83 girls). The echocardiographic measures were taken from conventional M-mode recording of the left ventricle (LV) parasternal long axis view. End diastolic septal (IVS) and LV posterior wall thickness (LVPW) and end diastolic as well as end systolic LV intracavity dimensions were retrospectively analyzed. The regression lines from all measured sizes are significantly different from those collected in the early eighties. Especially the thickness of the IVS is smaller. The regression lines are independent of gender. New reference values have been found which should replace the presently used ones. There is no difference between boys and girls. Why the muscular wall thicknesses are thinner than found 20 years ago needs to be further explored.

Improvement in diastolic left ventricular function after coronary artery bypass grafting as assessed by recordings of mitral annular velocity using Doppler tissue imaging

The aim of the study was to evaluate the changes in diastolic function after coronary artery bypass grafting (CABG), using pulsed-wave Doppler tissue imaging (DTI). Fifty-three patients with coronary artery disease were studied before and 3 and 12 months after CABG. Using pulsed-wave DTI, the mitral annular velocities were determined at 4 sites in the left ventricle (LV). Patients were also examined with dobutamine stress echocardiography and myocardial scintigraphy before and 3 months after CABG. The conventional transmitral velocity profiles were unchanged after CABG. DTI showed a marked improvement in diastolic LV function after CABG (early diastolic velocity: 7.5+/-1.9, 8.2+/-1.7 and 9.3+/-2.7 cm/s before and 3 and 12 months after CABG, respectively, P < 0.01). The improvement in early diastolic velocity was more pronounced in patients showing no sign of residual ischemia in comparison to those with residual ischemia determined by myocardial scintigraphy (7.41+/-2.04 vs. 9.25+/-2.61 cm/s, P < 0.01 in the nonischemic group; 7.29+/-2.16 vs. 8.41+/-2.55 cm/s, n.s., in the ischemic group). Before CABG, a significant increase in the systolic velocity (6.4+/-1.3 vs. 8.7+/-2.5 cm/s, P < 0.001), but not the early diastolic velocity (7.6+/-1.9 vs. 8.0+/-2.2 cm/s), was noted during stress echocardiography. Three months after CABG, both the systolic (6.5+/-1.3 vs. 9.3+/-2.8 cm/s, P < 0.001) and the early diastolic velocities (8.1+/-1.8 vs. 10.3+/-2.2 cm/s, P < 0.001) improved during stress echocardiography. The results of the present study show that diastolic function improves at rest and under stress in patients after CABG. The improvement was seen only in patients without postoperative signs of reversible ischemia.

Direct measurement of transmural laminar architecture in the anterolateral wall of the ovine left ventricle: new implications for wall thickening mechanics

Laminar, or sheet, architecture of the left ventricle (LV) is a structural basis for normal systolic and diastolic LV dynamics, but transmural sheet orientations remain incompletely characterized. We directly measured the transmural distribution of sheet angles in the ovine anterolateral LV wall. Ten Dorsett-hybrid sheep hearts were perfusion fixed in situ with 5% buffered glutaraldehyde at end diastole and stored in 10% formalin. Transmural blocks of myocardial tissue were excised, with the edges cut parallel to local circumferential, longitudinal, and radial axes, and sliced into 1-mm-thick sections parallel to the epicardial tangent plane from epicardium to endocardium. Mean fiber directions were determined in each section from five measurements of fiber angles. Each section was then cut transverse to the fiber direction, and five sheet angles (beta) were measured and averaged. Mean fiber angles progressed nearly linearly from -41 degrees (SD 11) at the epicardium to +42 degrees (SD 16) at the endocardium. Two families of sheets were identified at approximately +45 degrees (beta(+)) and -45 degrees (beta(-)). In the lateral region (n = 5), near the epicardium, sheets belonged to the beta(+) family; in the midwall, to the beta(-) family; and near the endocardium, to the beta(+) family. This pattern was reversed in the basal anterior region (n = 4). Sheets were uniformly beta(-) over the anterior papillary muscle (n = 2). These direct measurements of sheet angles reveal, for the first time, alternating transmural families of predominant sheet angles. This may have important implications in understanding wall mechanics in the normal and the failing heart.

The Glu27 allele of the beta2 adrenergic receptor increases the risk of cardiac hypertrophy in hypertension.

Cardiac and vascular remodeling occur in response to hypertension. Genetic background appears to modify the development of target organ damage (TOD). We evaluated the impact on hypertension-associated TOD of a highly polymorphic gene with elevated significance for the regulation of the cardiovascular system, the beta2AR gene. We recruited 775 hypertensives (mean +/- SE: age 53.5 +/- 0.5, from 20 to 84 years; female 32.7%; systolic (SBP)/diastolic (DBP) blood pressure: 159 +/- 1.2/101 +/- 0.6 mmHg) referred to the departmental outpatient clinic and screened them for the Arg16Gly, Gln27Glu, and Ile164Thr variants of beta2AR gene. We performed association analyses on clinical, anamnesis, anthropometrical and biochemical parameters as well as cardiac and vascular ultrasound. We found that the three polymorphisms did not affect blood pressure levels. Cardiac TOD appeared to be related to the Glu27 variant. In fact, the Glu27 allele associates with a 1.4-fold higher risk of developing cardiac hypertrophy, and directly correlated with larger systolic and diastolic left ventricle internal diameters. Vascular TOD was not affected by the three polymorphisms. Ancillary to our finding we observed that the Glu27 variant is associated with a higher incidence of dyslipidemia. Our data indicate that beta2AR gene polymorphisms participate in the determination of cardiac TOD associated with hypertension.

Short-Term Results With the Ross Procedure. Does the Etiology of Aortic Valvulopathy Affect the Outcome?

The Ross procedure has become established as an appropriate method for aortic valve replacement in children and young adults. There is controversy regarding the results of this surgical technique depending on whether the aortic valve disorder is congenital or acquired. The objective of this study was to analyze the outcome of this technique in different etiologies. We analyzed 61 patients who underwent the Ross procedure between November 1997 and November 2001. Age range was 6 to 54 years, and 44 patients (72%) were male. The mean duration of follow-up was 15.6 (10.6) months. The aortic valve lesion was stenosis in 17 patients, regurgitation in 22 and both in 22. The patients were divided into two groups: etiology was congenital in group I (40 patients) and acquired in group II (21 patients: 14 rheumatic, 2 degenerative, 2 endocarditis and 3 other). Pre-intervention data showed significant differences in age, functional class and percentage of patients with previous cardiac surgery. In the last follow-up examination, autograft gradient and homograft gradient were similar in both groups. Diastolic and systolic diameters and left ventricle ejection fraction were normal in both groups and did not differ between groups. Major events during follow-up were: 1 patient died, 1 patient had endocarditis, and 2 patients needed stent implantation in the homograft in group I; 2 patients in group II underwent reoperation because of severe autograft dysfunction. There were no statistically significant differences between groups. Short-term morbidity and mortality associated with the Ross procedure are low in patients with either congenital or acquired aortic valvulopathy.

Echocardiographic assessment of age-associated changes in systolic and diastolic function of the female F344 rat heart

Aging is associated with hypertrophy, dilatation, and fibrosis of the left ventricle (LV) of the heart. Advances in echocardiographic assessment have made it possible to follow changes in cardiac function in a serial, noninvasive manner. The purpose was to determine whether there is echocardiographic evidence of age-associated changes in chamber dimensions and systolic and diastolic properties of the female Fischer 344 (F344) rat heart. On the basis of previous invasive studies, it was predicted that echocardiographic assessment would detect age-associated changes in indexes of systolic and diastolic function. Rats were sedated with 1.5% isoflurane and placed in the supine position. Two-dimensional images and two-dimensionally guided M-mode, Doppler M mode, Doppler tissue, and pulsed-wave Doppler recordings were obtained from the parasternal long axis, parasternal short axis, and/or apical four-chamber views as per convention by using a 15-MHz linear array or 8-MHz phased-array transducer or a GE S10-MHz phased-array transducer. Compared with young adult 4-mo-old rats, there is a significant decrement in the resting systolic function of the LV in 30-mo-old female F344 rats as evidenced by declines in LV ejection fraction (80 +/- 9 vs. 89 +/- 5%; mean +/- SD), fractional shortening (43 +/- 9 vs. 54 +/- 8%) and velocity of circumferential fiber shortening (2.43 +/- 0.53 vs. 2.99 +/- 0.50 circ/s). Evidence for age-associated differences in diastolic function included an increase in isovolumic relaxation time (25.0 +/- 7.6 vs. 17.2 +/- 4.4 ms) and decreases in the tissue Doppler peak E waves at the septal annulus and at the lateral annulus of the mitral valve. The modest changes in systolic and diastolic LV function that occur with advancing age in the female F344 rat are likely to reduce the capacity of the heart to respond to hemodynamic challenges.

Cardiovascular physiology-changes with aging.

With aging there are changes in the cardiovascular system, which result in alterations in cardiovascular physiology. The changes in cardiovascular physiology must be differentiated from the effects of pathology, such as coronary artery disease, that occur with increasing frequency as age increases. The changes with age occur in everyone but not necessarily at the same rate, therefore accounting for the difference seen in some people between chronologic age and physiologic age. The changes in the cardiovascular system associated with aging are a decrease in elasticity and an increase in stiffness of the arterial system. This results in increased afterload on the left ventricle, an increase in systolic blood pressure, and left ventricular hypertrophy, as well as other changes in the left ventricular wall that prolong relaxation of the left ventricle in diastole. There is a dropout of atrial pacemaker cells resulting in a decrease in intrinsic heart rate. With fibrosis of the cardiac skeleton there is calcification at the base of the aortic valve and damage to the His bundle as it perforates the right fibrous trigone. Finally there is decreased responsiveness to beta adrenergic receptor stimulation, a decreased reactivity to baroreceptors and chemoreceptors, and an increase in circulating catecholamines. These changes set the stage for isolated systolic hypertension, diastolic dysfunction and heart failure, atrioventricular conduction defects, and aortic valve calcification, all diseases seen in the elderly.

The Role of Tissue Doppler Imaging as a New Diagnostic Option in Evaluating Left Ventricular Function

The widespread use of the pulsed Doppler echocardiography has facilitated the noninvasive evaluation of hemodynamic abnormalities of the left atrium and left ventricle (LV) based on transmitral and pulmonary venous flow velocity patterns. However, it has been shown that loading conditions, especially preload, influence the indices obtained from these velocity patterns. Recently, tissue Doppler imaging (TDI) has been applied to the clinical setting to assess LV myocardial function. In particular, this procedure has the following characteristics: 1) it can provide circumferential and longitudinal information for the LV myocardium; 2) the early diastolic LV myocardial parameters determined by TDI are not influenced by preload; 3) LV myocardial contractility can be evaluated from the early systolic parameters; 4) LV systolic and diastolic asynchrony can be detected; 5) myocardial velocity gradients obtained from color-coded TDI are not influenced by the entire heart motion; and 6) TDI parameters are useful for establishing the prognosis of patients with LV heart failure. In the future, technologic improvements will elucidate the tissue characteristics based on tissue velocity information in patients with myocardial disease or allow the detection of endocardial and/or epicardial involvement of the LV myocardium in patients with ischemic heart disease.

Exceptional survival of a patient with large ventricular septal defect, bidirectional shunt, and severe pulmonary valve stenosis

A 74-year-old man has survived in good health for an exceptionally long time despite the presence of a moderate-to-large-sized membranous ventricular septal defect (VSD). He has remained acyanotic with New York Heart Association class I function. Transthoracic and transesophageal echocardiography with color flow Doppler demonstrated a membranous VSD with left-to-right and right-to-left bidirectional shunts during ventricular systole and diastole, respectively, with an right ventricular systolic pressure of 93 mm Hg, dilation of the atria and the right ventricle, and right ventricular hypertrophy. The pulmonary valve was severely stenotic with transpulmonary valve peak velocity of 6.1 m/s and a peak pressure gradient of 147 mm Hg. The pulmonary artery and inferior vena cava were mildly dilated, and the left ventricular dimension and systolic function were normal. Transesophageal echocardiography with saline solution microbubble injection demonstrated positive contrast effect in the left ventricle in diastole confirming a right-to-left shunt at the ventricular level. This man is currently the oldest survivor with a moderate-to-large-sized membranous VSD reported in the literature. (J Am Soc Echocardiogr 2002;15:665-7.)

The role of diastolic pump flow in centrifugal blood pump hemodynamics.

We tried to verify the hypothesis that increases in pump flow during diastole are matched by decreases in left ventricular (LV) output during systole. A calf (80 kg) was implanted with an implantable centrifugal blood pump (EVAHEART, SunMedical Technology Research Corp., Nagano, Japan) with left ventricle to aorta (LV-Ao) bypass, and parameters were recorded at different pump speeds under general anesthesia. Pump inflow and outflow pressure, arterial pressure, systemic and pulmonary blood flow, and electrocardiogram (ECG) were recorded on the computer every 5 ms. All parameters were separated into systolic and diastolic components and analyzed. The pulmonary flow was the same as the systemic flow during the study (p > 0.1). Systemic flow consisted of pump flow and LV output through the aortic valve. The ratio of systolic pump flow to pulmonary flow (51.3%) did not change significantly at variable pump speeds (p > 0.1). The other portions of the systemic flow were shared by the left ventricular output and the pump flow during diastole. When pump flow increased during diastole, there was a corresponding decrease in the LV output (Y = -1.068X + 51.462; R(insert)(2) = 0.9501). These show that pump diastolic flow may regulate expansion of the left ventricle in diastole.

Extension of a Pulmonary Blastoma Into the Left Atrium

Extension of a Pulmonary Blastoma Into the Left Atrium

THE RELATIONSHIP BETWEEN DIASTOLIC PUMP FLOW OF THE CENTRIFUGAL BLOOD PUMP AND THE LEFT VENTRICULAR OUTPUT THROUGH THE AORTIC VALVE

Aim: We tried to verify the hypothesis that increases in pump flow during diastole are matched by decreases in left ventrickle output during systole. Methods and materials: Two calves (68 and 130Kg) were implanted with the implantable centrifugal blood pump (EVAHEART, SunMedical Corp. Japan) with LV-Ao bypass and parameters were recorded at different pump speeds under the general anesthesia. Pump inflow and outflow pressure, arterial pressure, pump and pulmonary blood flow, and ECG were recorded on the computer every 5 msec. Additionally, echocardiography was done for one of two calves 30 days after implant. All parameters were separated into systolic and diastolic components and analyzed. Results: The pulmonary flow was the same as the systemic flow and blood pressure did not change during examination (p>0.1). The systemic flow consisted of the pump flow and LV output through the aortic valve. The ratio of the systolic pump flow to the pulmonary flow (51.0%) did not change significantly, at variable pump speeds (p>0.1). The other portions of the systemic flow were shared by the left ventricular output and the pump flow during diastole. When the pump flow increased during diastole there was a corresponding decrease in the left ventricular output. The volume study of echocardio-graphy also showed the same results. Conclusions: These show that the pump diastolic flow may regulate expansion of the left ventricle in diastole.