Changes in porcine transmitral flow velocity pattern and its diastolic determinants during partial coronary occlusion.
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OBJECTIVES: To define the mechanical determinants of transmitral flow and the effect of heart rate during regional ischemia. BACKGROUND: Myocardial ischemia changes the transmitral flow velocity pattern due to disease-induced changes in the heart's diastolic properties. METHODS: Regional ischemia was produced in 12 pigs by partially occluding the left anterior descending coronary artery until segment-length shortening in the ischemic region fell by 20%. Transmitral flow velocity patterns and their determinants were measured under two conditions, baseline and ischemia, at two heart rates, 70 and 90 beats/min. RESULTS: Regional ischemia had a significant effect on two determinants of filling: relaxation, which was slower, and chamber stiffness, which increased. These changes were associated with reduced contractility and increased myocardial stiffness, resulting in an early transmitral flow pattern that was flatter and narrower, but no change in the late flow pattern. Moderate increases in heart rate accelerated relaxation and decreased atrioventricular pressure gradient but had no effect on contractility or myocardial or chamber stiffness, resulting in an early transmitral flow pattern that was flatter and narrower and an increased late flow velocity. CONCLUSIONS: This model of regional ischemia leads to a flatter and narrower early transmitral flow velocity pattern and no change in late flow due to a combination of slowed left ventricular relaxation and increased chamber stiffness. Reflex increases in heart rate that accompany ischemia tend to mask this effect. (+info)
Assessment of the temporal relationship between left ventricular relaxation and filling during early diastole using pulsed Doppler echocardiography and tissue Doppler imaging.
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The study investigated the temporal relationship between left ventricular (LV) relaxation and filling during early diastole. The transmitral flow (TMF) velocity by pulsed Doppler echocardiography and LV wall motion velocity by pulsed tissue Doppler imaging (TDI) were evaluated in 57 patients with various heart diseases and 33 normal controls. The patients were classified into 2 groups according to the ratio of the peak early diastolic to atrial systolic TMF velocity (E/A): (1) the high A group included 44 patients with an E/A < or = 1, and (2) the pseudonormalization group included 13 patients with an E/A > 1. The isovolumic relaxation time (IRT) from the aortic component of the second heart sound (IIA) to the onset of the E wave of the TMF was measured. The peak early diastolic velocity of the LV posterior wall (Ew) and time from the IIA to the onset of the early diastolic wave (IIA-Ewo) were determined from the LV wall motion velocity assessed by pulsed TDI. The Ew was lower in the pseudonormalization and high A groups than in the control group. The IIA-Ewo was significantly longer in the pseudonormalization and high A groups than in the control group. The time constant of the LV pressure decay at isovolumic diastole (tau) correlated negatively with the Ew, and correlated positively with the IIA-Ewo in all groups. The IIA-Ewo was equal to or shorter than the IRT in control subjects, and was longer than the IRT in patients in the pseudonormalization group. In conclusion, the temporal relationship between LV relaxation and filling during early diastole varied according to the subjects' hemodynamic status. Analysis of TMF by pulsed Doppler echocardiography and LV wall motion velocity by pulsed TDI was useful for detailed evaluation of early diastolic LV hemodynamics. (+info)
The interaction between pindolol and epinephrine contained in local anesthetic solution to the left ventricular diastolic filling velocity in normal subjects.
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To evaluate the interaction between the nonselective beta-blocker, pindolol, and epinephrine contained in a local anesthetic solution, the left ventricular diastolic filling velocity was examined with pulsed Doppler echocardiography. Arterial blood pressure (BP), the R-R interval on the electrocardiogram (RR), and Doppler echo-cardiographic measurements were recorded in seven healthy volunteers after 45 micrograms of epinephrine contained in lidocaine (L-E) was injected in the maxilla after pretreatment with 5 mg of pindolol. The administration of L-E caused the elevation of BP and an increase in RR interval. Peak early (E) and peak atrial (A) filling velocities decreased, whereas isovolumic relaxation time (IVRT) and diastolic filling period (DFP) were prolonged. Although the ratio of E to A (E/A) remained unchanged, E/A/DFP was reduced. In contrast, when L-E was given without pindolol pretreatment, RR interval was shortened and BP was unchanged. The increase of both E and A velocities and the shortening of both IVRT and DFP were observed. E/A remained unchanged but E/A/DFP was increased. These results suggested that L-E caused opposite effects on the left ventricular filling velocity in the presence or absence of pindolol. We conclude that epinephrine activates the left ventricular relaxation rate but impairs it in the presence of pindolol. (+info)
Pattern of pulmonary venous blood flow in the hypoplastic left heart syndrome in the fetus.
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OBJECTIVE: To determine whether restriction at the atrial septum in the newborn with hypoplastic left heart syndrome can be predicted accurately by examining the pattern of pulmonary venous flow in the fetus. A restrictive atrial septum can contribute to haemodynamic instability before surgery for this lesion and has been associated with an increased mortality. DESIGN: Pulmonary venous pulsed Doppler tracings were compared between fetuses with hypoplastic left heart syndrome and controls. The size of the atrial septal defect on the postnatal echocardiogram was graded according to the degree of restriction. Pulsed Doppler tracings of pulmonary venous blood flow were obtained in 18 fetuses with left atrial outflow atresia and compared with 77 controls, adjusted for gestational age. Postnatal echocardiograms were available for analysis in 13 of 18 neonates. SETTING: A tertiary referral centre for fetal cardiology and paediatric cardiac surgery. RESULTS: Fetuses with hypoplastic left heart syndrome were different from controls in all pulmonary vein indices measured. As assessed from the postnatal echocardiogram, there were seven fetuses with a restrictive atrial septum. In these fetuses, the systolic flow velocity (p < 0.01), S/D ratio (p < 0.01), and peak reversal wave (p < 0.001) in the pulmonary vein tracing showed a good correlation with the degree of restriction. CONCLUSIONS: The Doppler pattern of pulmonary venous flow in the fetus with hypoplastic left heart syndrome appears to be a reliable predictor of restriction of the atrial septum in the neonate. This may help in the immediate post-delivery management of these infants before surgery. (+info)
Importance of left atrial appendage flow as a predictor of thromboembolic events in patients with atrial fibrillation.
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AIM: The purpose of this study was to investigate the role of transoesophageal echocardiography in predicting subsequent thromboembolic events in patients with atrial fibrillation. METHODS AND PATIENTS: Transoesophageal echocardiography was performed in 88 patients with documented paroxysmal (n=53) or chronic atrial fibrillation (n=35) to assess morphological and functional predictors of thromboembolic events. Prospective selection was from patients with non-valvular atrial fibrillation who had undergone transoesophageal echocardiography because of previous thromboembolism (n=30); prior to electrical cardioversion (n=31); or for other reasons (n=27). All patients were followed up for 1 year. RESULTS: During the period of follow-up new thromboembolic events occurred in 18 of 88 patients (20%/year); 16 of these patients had a stroke and two a peripheral embolism. Univariate analysis revealed that previous thromboembolism (P<0.005; odds ratio 5.3 [CI 1.9, 12. 1]), history of hypertension (P<0.01; odds ratio 4.0 [CI 1.4, 10.4), presence of left atrial spontaneous echo contrast (P<0.025; odds ratio 3.5 [CI 1.2, 10.0]), and presence of left atrial appendage peak velocity +info)
Regional diastolic function in ischaemic heart disease using pulsed wave Doppler tissue imaging.
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AIMS: The aim of this study was to determine the utility of pulsed wave Doppler tissue imaging in the evaluation of regional left ventricular diastolic function in patients with ischaemic heart disease. METHODS AND RESULTS: In 30 normal subjects and 43 patients with ischaemic heart disease, Doppler tissue imaging was performed in each of the 16 segments of the myocardium. The following diastolic pulsed wave Doppler tissue imaging parameters were obtained for each segment: (1) regional early diastolic peak velocity (regional e wave cm.s-1); (2) regional late diastolic peak velocity (regional a wave cm.s-1); (3) regional diastolic e/a velocity ratio; and (4) the regional isovolumic relaxation time, defined as the time interval from the second heart sound to the onset of the diastolic E wave. In patients with ischaemic heart disease, each of these parameters was evaluated and compared in ischaemic and normally perfused segments, based on the presence or absence of obstructive lesions of the supplying coronary artery. In patients with coronary artery disease, several differences were observed between diseased and normal wall segments: the mean segmental peak early diastolic velocity (e wave) was reduced (mean +/- SD: 6.4 +/- 2.1 cm.s-1 vs 8.5 +/- 2.8 cm.s-1; P < 0.01); the e/a diastolic velocity ratio was decreased (0.95 +/- 0.3 vs 1.5 +/- 0.6, respectively; P < 0.01) and the regional isovolumic relaxation time was prolonged (104 +/- 36.7 ms vs 69.6 +/- 30 ms; P < 0.01. No differences were observed in any of these parameters between the normally perfused segments of ischaemic patients and normal subjects. Patients with a normal transmitral diastolic Doppler inflow pattern had a mean of 3.7 +/- 2.7 myocardial segments with a local e/a pulsed wave Doppler tissue imaging velocity ratio < 1, fewer than those with an inverted diastolic transmitral Doppler inflow pattern (10.3 +/- 3 segments; P < 0.001). Overall sensitivity and specificity for an inverted local e/a ratio and a local isovolumetric relaxation time > or = 85 ms were of 62% and 72% and 69% and 80%, respectively. CONCLUSION: Regional diastolic wall motion is impaired at baseline in ischaemic myocardial segments, even when systolic contraction is preserved. Pulsed wave Doppler tissue imaging is a useful non-invasive technique which allows the assessment of regional diastolic performance and dynamics of the left ventricular myocardium. Further studies are required to define this role in the evaluation of coronary heart disease. (+info)
Aortic root dilatation in young men with normally functioning bicuspid aortic valves.
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OBJECTIVE: To evaluate the dimensions of the aortic root in a selected population of young males with isolated normally functioning bicuspid aortic valve. DESIGN AND SETTING: Echocardiographic and Doppler evaluation of conscripts with bicuspid aortic valve at the time of military pre-enrolment screening in two military hospitals. SUBJECTS AND METHODS: 66 consecutive young men with a normally functioning bicuspid aortic valve were studied to assess aortic size at four aortic levels: annulus, sinuses of Valsalva, supra-aortic ridge, and proximal ascending aorta; 70 consecutive normal young subjects, matched for age and body surface area, were used as controls. RESULTS: In men with a bicuspid aortic valve, the diameter of the aortic root was significantly larger than in controls at the sinuses (3.16 (0.37) v 2.87 (0.31) cm, p < 0.001), at the supra-aortic ridge (2.64 (0.46) v 2.47 (0.28) cm, p = 0.01), and at the level of the proximal ascending aorta (3.12 (0.48) v 2.69 (0.28) cm, p < 0.001). The prevalence of aortic root dilatation was 7.5% at the annulus (5/66), 19.6% at the sinuses (13/66), 15% at the supra-aortic ridge (10/66), and 43.9% at the ascending aorta (29/66); 32 subjects (48%) had aortic root dimensions comparable with controls, while 34 (52%) had definitely abnormal aortic root dimensions. CONCLUSIONS: Aortic root enlargement in people with a bicuspid aortic valve occurs independently of haemodynamic abnormalities, age, and body size. However, there appear to be different subgroups of young adults with bicuspid aortic valves, one of which is characterised by aortic dilatation, possibly caused by a congenital abnormality of the aortic wall. (+info)
Noninvasive evaluation of pulmonary capillary wedge pressure in patients with acute myocardial infarction by deceleration time of pulmonary venous flow velocity in diastole.
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OBJECTIVES: This study investigates the correlation between deceleration time of diastolic pulmonary venous flow (PV-DT) and of early filling mitral flow (LV-DT), and pulmonary capillary wedge pressure (PCWP) in patients with acute myocardial infarction (AMI). BACKGROUND: An earlier study suggests that Doppler-derived LV-DT provides an accurate means of estimating PCWP in postinfarction patients with left ventricular systolic dysfunction. Furthermore, recent studies have suggested that PCWP correlates better with PV-DT than with LV-DT. However, the value of PV-DT and LV-DT for assessment of PCWP in patients with AMI has not been evaluated. METHODS: In 141 consecutive patients with AMI, we measured PV-DT and LV-DT by Doppler echocardiography, and compared these variables with PCWP measured using a Swan-Ganz catheter. RESULTS: There was a weak negative correlation between the LV-DT and PCWP (r = -0.54). Although the sensitivity of < or =130 ms in LV-DT in predicting > or =18 mm Hg in PCWP was high (86%), its specificity was low (59%). On the other hand, a very close negative correlation was found between PV-DT and PCWP (r = -0.89). The sensitivity and specificity of < or =160 ms in PV-DT in predicting > or =18 mm Hg in PCWP were 97% and 96%, respectively. CONCLUSIONS: In patients with AMI, Doppler-derived PV-DT showed a stronger correlation with PCWP than LV-DT. (+info)