Coronary Artery Flow Velocity Research Articles

Behavior of both epicardial and intramural coronary artery flow velocities in various models of myocardial hypertrophy: Role for left ventricular outflow tract obstruction

The assessment of coronary flow velocity is becoming crucial in the diagnosis and management of several cardiac dysfunctions and conventional Doppler echocardiography is currently the technique most widely used for detecting their abnormalities noninvasively. We sought to evaluate the differences in coronary flow velocity using conventional transthoracic Doppler echocardiography, measuring both the left anterior descending and such intramural (IM) coronary arteries' flow, among the following 4 categories of patients with myocardial hypertrophy: group A, obstructive hypertrophic cardiomyopathy (n = 12); group B, nonobstructive hypertrophic cardiomyopathy (n = 10); group C, left ventricular hypertrophy (LVH) due to hypertension (n = 10); and group D, LVH due to aortic valve stenosis (n = 10). No significant difference between the 4 groups was found with respect to the left anterior descending velocity. Diastolic peak (P < .01) and mean (P < .05) velocities in the IM arterioles were significantly higher in patients from groups A and D than in groups B and C. At multivariate analysis, both dynamic (group A) and fixed (group D) systolic peak gradients, measured by continuous wave Doppler sampling through the left ventricular (LV) outflow tract or the aortic valve, respectively, were found to be major determinants of the IM diastolic velocity, independently on the LV mass. About 75% of patients with obstructive hypertrophic cardiomyopathy showed IM peak and mean velocity >100 cm/s and >70 cm/s, respectively (P = .005). These findings likely suggest [corrected] a role for the LV systolic obstruction within the intricate adaptive mechanisms of coronary blood flow to LVH.

A short period of apnoea causes a marked increase in coronary flow velocity: a transthoracic pulsed wave Doppler study

Coronary artery flow velocity during a short period of apnoea was investigated by transthoracic Doppler recording in 10 healthy men, aged 24-52. During breath holding for 29 +/- 6 s the oxygen saturation in the finger, measured by pulse oxymetry, decreased from 97.5 +/- 0.8 to 90.0 +/- 3.2% (P < 0.001). The maximal coronary blood flow velocity in the left anterior descending artery increased by 62% from 0.26 +/- 0.09 to 0.42 +/- 0.10 m s(-1) and the mean diastolic flow velocity by 47% from 0.19 +/- 0.04 to 0.28 +/- 0.08 m s(-1) (P < 0.001). In most subjects the increase of velocity started already after a few seconds of apnoea. Besides theoretical implications the results show that it is very important to be aware of the higher velocity during apnoea in order to avoid misinterpretation when using breath holding during magnetic resonance imaging or Doppler recording of coronary flow.

Spiral phase velocity mapping of left and right coronary artery blood flow: Correction for through‐plane motion using selective fat‐only excitation

To develop a method of correcting both right and left coronary artery flow velocities for the through-plane motion of the vessel, in order to allow details in the temporal flow profiles to be viewed. The methods developed use selective excitation and velocity mapping of the epicardial fat surrounding the artery, either in a separate acquisition (temporal resolution = 22 msec) or interleaved with the water-excitation acquisition (temporal resolution = 44 msec) used to determine coronary blood flow velocities. The two methods were compared in 10 right and 13 left coronary arteries in healthy volunteers. For the right coronary arteries, correction for through-plane motion significantly reduces the mean systolic flow velocity (75.3 mm/second vs. 90.0 mm/second, P < 0.01), while the mean diastolic flow velocity is unchanged (96.8 mm/second vs. 94.5 mm/second, P = ns). The resulting profiles are biphasic, with approximately equal flow in systole and diastole. For the left arteries, correction for through-plane motion reduces the mean systolic flow velocity (25.0 mm/second vs. 72.8 mm/second, P < 0.001), resulting in the expected diastolic predominant flow profiles. For the right arteries, there were no significant differences in the mean systolic and mean diastolic velocities after correction with the separate fat-excitation acquisition, and after correction the poorer temporal resolution combined water excitation/fat excitation acquisition. However, for the left coronary arteries, the combined water excitation/fat excitation acquisition resulted in a slight reduction in the mean diastolic velocity (121.5 mm/second vs. 130.9 mm/second, P < 0.05). Selective excitation of the surrounding epicardial fat enables through-plane correction of both left and right coronary flow velocities, enabling the temporal details of flow velocity to be viewed. With a combined WE/FE acquisition, this can be performed without extending the study duration; however, the reduced temporal resolution and temporal mismatch of the excitations results in a blunting of rapidly changing flow profiles. As such, it may be less suitable for the left coronary artery, which has a greater range of through-plane motion than the right, and correction using separate WE and FE acquisitions, or the adjacent myocardium, may be preferable.

Early assessment of coronary flow reserve by transthoracic Doppler echocardiography predicts late remodeling in reperfused anterior myocardial infarction

Background Microvascular integrity is an essential determinant of favorable late outcome in reperfused myocardial infarction. Coronary flow reserve (CFR) can be assessed by transthoracic Doppler echocardiography and provides a functional estimate of microvascular integrity downstream from the patent infarct-related vessel. Objective We sought to assess the effects of CFR in predicting late left ventricular (LV) remodeling in patients with reperfused acute anterior myocardial infarction treated with primary angioplasty. Methods In all, 31 patients admitted with acute anterior myocardial infarction underwent primary angioplasty of the infarct-related vessel. After angioplasty, angiographic thrombosis in myocardial infarction (TIMI) grade and myocardial blush were scored. On the first day, all underwent stress echocardiography and CFR evaluation of left anterior descending coronary artery by transthoracic Doppler. All patients had resting 2-dimensional echocardiography at 1, 3, and 6 months for assessment of LV function. Results CFR could be successfully assessed in 31 patients. After 6 months 5 patients showed LV dilatation (group I), whereas 26 patients did not show significant variation (group II). On day 1, CFR was higher (group I = 1.43 ± 0.11 vs group II = 1.67 ± 0.26, P = .005) and the deceleration time of diastolic left anterior descending coronary artery flow velocity was longer (group I = 212 ± 41.4 milliseconds vs group II = 286 ± 106.7 milliseconds, P < .02) in patients without, compared with those with LV remodeling, whereas there was no difference in angiographic parameters. Conclusion Early assessment of CFR and the pattern of baseline diastolic coronary flow velocity by transthoracic Doppler echocardiography is feasible, safe, and more useful than angiographic indices in identifying patients at high risk of remodeling in spite of successful primary angioplasty.

Different Responses of Myocardial and Cerebral Blood Flow to Cord Occlusion in Exteriorized Fetal Sheep

Type and duration of fetal asphyxial insult affect the distribution of blood flow to the heart and brain. The purpose of this study was to describe dynamic and quantitative changes in regional myocardial and cerebral blood flow (CBF) during fetal asphyxia induced by total occlusion of the umbilical cord. Eleven exteriorized fetal sheep were subjected to total umbilical cord occlusion and five fetal sheep served as sham controls. Regional blood flow (BF) to the brain and heart was quantified using radioactive microspheres before and after 5 min of occlusion and finally when fetal mean arterial blood pressure had decreased below 25 mm Hg, 9.8 (0.8) [mean (SD)] min after occlusion. Right coronary arterial (RCA) blood flow velocity and carotid BF were registered continuously. Mean values of arterial pH and oxygen content (mL O(2)/100 mL) were 7.08 (0.11) and 4.4 (2.9) before cord occlusion and decreased to 6.83 (0.05) and 1.4 (0.9) at 5 min after occlusion (p < 0.01, respectively). Carotid BF was significantly below preocclusion values by 2.5 min (p < 0.05), whereas RCA velocity time integral per minute remained above preocclusion values for 9 min. CBF decreased from 316 (24) before cord occlusion to 156 (30) mL/min/100 g at 5 min (p < 0.01), whereas right myocardial BF was maintained at 792 (125) and 751 (183) mL/min/100 g, respectively. CBF decreased rapidly after total cord occlusion whereas myocardial BF increased and was maintained until shortly before cardiac arrest, suggesting the myocardium to be better preserved during this type of insult in already partially asphyxiated fetuses.

Intra-aortic balloon pumping: effects on left ventricular diastolic function.

The intra-aortic balloon pump is the most widely used form of temporary cardiac assist and often utilised in patients before and after cardiac surgery. Several effects of balloon counter-pulsation have been reported previously, but its effect on left ventricular diastolic function has not been thoroughly investigated. The aim of this study is to examine the effect of the intra-aortic balloon pump on left ventricular wall motion and transmitral flow. We studied 20 patients in the intensive care unit, less than 36 h following cardiac surgery. We recorded left anterior descending coronary artery and transmitral E-wave flow velocities using transesophageal echocardiography pulsed Doppler. We also recorded left ventricular long axis free-wall movement using M-mode. The intra-aortic balloon pump was set to full augmentation and recordings were made at pumping cycles 1:1, 1:2, 1:3, and when the pump was on stand-by, leaving a minimum of 5 min between the pumping modes to allow the return to control conditions. In order to eliminate time effects, the sequence of recording was varied between patients using a 4 by 4 Latin-square. The peak diastolic left anterior descending coronary artery and transmitral E-wave flow velocities, and left ventricular free-wall early diastolic lengthening velocity increased significantly with intra-aortic balloon pumping cycles 1:1, 1:2 and 1:3 compared to their value with the pump on stand-by, all P < 0.001. The increase in peak transmitral E-wave flow velocity correlated with the increase in peak left anterior descending coronary artery diastolic flow velocity (r = 0.74, P = 0.02), and with the increase in left ventricular free-wall early diastolic lengthening velocity (r = 0.80, P < 0.001). Using the intra-aortic balloon pump post-cardiac surgery significantly increases peak diastolic left anterior descending coronary artery flow velocities and left ventricular free-wall early diastolic lengthening velocity, whose increase explains the increase in peak transmitral E-wave velocity. Although coronary flow is epicardial and mitral flow is intracardial, their close relationship suggests an improvement in left ventricular diastolic function with intra-aortic balloon pump.

Noninvasive visualization and measurement of posterior descending coronary artery flow velocity by transthoracic Doppler echocardiography in normal children

Noninvasive visualization and measurement of posterior descending coronary artery flow velocity by transthoracic Doppler echocardiography in normal children

Correlation of transthoracic Doppler echocardiography and magnetic resonance imaging in measuring left anterior descending artery flow velocity and time‐course of dipyridamole‐induced coronary flow increase

There is an increasing need for new, functional and more quantitative parameters to assess coronary arterial function, for the purposes of evidence‐based medicine. Coronary arterial function has been widely studied using pharmacological stimulation induced by dipyridamole or adenosine. Coronary flow reserve (CFR), defined as the ratio of pharmacologically induced hyperemic flow divided by basal flow, has been found to be an important functional index in both the clinical and subclinical stages of cardiovascular diseases. Ten healthy male volunteers were studied to compare transthoracic Doppler echocardiography (TTE) and MRI for measuring left anterior descending coronary artery (LAD) flow velocity and CFR. Additionally, the time‐response curve of dipyridamole infusion was studied in five healthy males using TTE. Assessment of blood flow velocity, measured as MDV, PDV and VTI indicated Pearson's correlation coefficients of 0.88, 0.85 and 0.70, respectively, between flow velocity measurements performed using TTE and MRI. The results indicate that, despite minor differences in LAD diastolic velocities measured by TTE and MRI, the correlation of the LAD diastolic velocities measured using both methods are good and both methods are feasible for measuring CFR. Moreover, TTE has the unique capability of continuous measurement of LAD flow velocity, which allowed assessment of the time‐response curve for dipyridamole‐induced increase in LAD flow velocity in this study. This study indicates that the TTE method may be used in sequential or on‐line monitoring of LAD blood flow velocity and therefore can be applied to evaluate the time‐ or dose‐response effects of infused drugs in the coronary circulation of humans.

Coronary Artery Flow Velocity Pattern Predicting Myocardial Recovery after Acute Anterior Myocardial Infarction

Background and Objectives:The relationship between the coronary artery flow velocity pattern on the distal left anterior descending coronary artery (LAD), using transthoracic Doppler echocardiography (TTE) and myocardial recovery, following an acute myocardial infarction (MI), has not been studied. Subjects and Methods:The coronary flow velocity at the distal LAD was recorded with TTE, immediately, on the 7th day, and at an average, on the 10th month, in 36 patients following an acute anterior MI. The peak diastolic coronary flow velocity (PDV), the initial velocity pattern and alteration in the velocity pattern, during the follow-up period, were analyzed by the changes in the left ventricular systolic function and the anterior apical wall motion. The subjects were divided into two groups: the recovery (R) group: n=24, M:F=14:10, mean age=60±9 yrs; and the non-recovery (NR) group: n=12, M:F=11:1, mean age=61±11 yrs, according to their myocardial recovery status. Results: The early flow velocity at the distal LAD, using TTE after MI, was divided into 4 patterns; a normal biphasic flow pattern, with a larger diastolic and a smaller systolic component; a pattern, with slow flow and deceleration slope; a pattern, with a retrograde flow; and a pattern, with a rapid diastolic deceleration slope and an early systolic reversal flow. A normal biphasic flow pattern was observed in 16 (66%) of the R-group (n=24), and 1 (8%) of the NR-group (n=12) (p=0.001) patients. A rapid diastolic deceleration slope and an early systolic reversal flow pattern was only observed in 4 of the NR-group (n=12) (p=0.003) patients. Conclusion:The patterns, with a rapid diastolic deceleration slope and a systolic retrograde flow, early after MI, and a persistent slow flow velocity during follow up, are related to poor myocardial recovery following an acute anterior MI. (Korean Circulation J 2003;33 (4):259-268)

Analysis of Coronary Artery Flow Patterns in Patients with Chest Pain and Normal Coronary Angiogram: Study Using Transthoracic Doppler Echocardiography

Background and Objectives:The purpose of this study was to analyze the patterns of coronary artery flow, using transthoracic Doppler echocardiography (TTE), in subjects with chest pains and normal coronary angiograms. Subjects and Methods:93 patients (M:F = 34:59, mean age:57±11 years) with chest pains and normal coronary angiograms were included in this study. After obtaining baseline clinical data, an exercise treadmill test (ETT) was performed, according to the Bruce protocol. The peak diastolic coronary artery flow velocity (PDV), at rest, and the coronary flow reserve (CFR), in the distal left anterior descending coronary artery (LAD), were estimated, using dipyridamole, with TTE. After the administration of angiotensin II receptor (AT II) blockers to 12 patients with a CFR <2.1. The ETT and CFR were followed up. Results:Of the 93 subjects 63 (67.7%) were female, and 53 (56.9%) had a history of hypertension and 61 (65.5%) showed ST or T abnormality on their resting ECG. Five subjects (5.3%) had metabolic or hematologic problems, such as hyperthyroidism or anemia. Twenty-seven (30.3%) of the 89 subjects showed a reduced CFR value less than 2.1. The subjects with horizontal or down-sloping ST depression on their ETT showed a decreased CFR, compared with those with no ST shifting or an up-sloping ST depression (p<0.05, respectively). Twenty-six (27.9%) of the 93 subjects showed a slow coronary flow velocity <14 cm/sec, and 15 (83.3%) of 18 subjects who estimated CFR had CFR ≥2.1. In 7 (58.3%) of 12 subjects with a CFR <2.1, their CFR increased, with an improvement of the ETT results, following the administration of the AT II blocker, after an average 19±9 months. Conclusion:The patients with chest pains and normal coronary angiograms have a heterogeneous clinical spectrum, such as hypertensin, slow flow, reduced CFR, and so on. These subjects need treatment according to the etiology and pathogenesis of their condition, which can be followed up by coronary flow measurements, using TTE. (Korean Circulation J 2003;33 (3):205-211)

Coronary flow abnormalities in neonates with aortic stenosis

Left coronary artery flow velocities in neonates were determined noninvasively with transthoracic pulsed wave Doppler ultrasonography. In normal subjects (n = 30) there was diastolic flow predominance with median (range) peak flow velocity in diastole, 23.8 cm/s (12.7 to 51.3 cm/s), and median peak flow velocity in systole, 12.7 cm/s (7.8 to 35.0 cm/s). In 3 neonates with severe aortic stenosis, retrograde left coronary flow throughout systole was observed before surgery. In these patients there was forward systolic flow 4 to 8 days after successful surgical valvulotomy was performed. (J Pediatr 2000;137:875-7)

Myocardial blood flow and myocardial uptake of (201)Tl and (99m)Tc-sestamibi during coronary vasodilation induced by CGS-21680, a selective adenosine A(2A) receptor agonist.

We investigated the hemodynamic and coronary vasodilatory effects of CGS-21680, a potent selective adenosine A(2A) agonist, as well as its potential use as a new stress modality in combination with perfusion scintigraphy. A stenosis of the left anterior descending coronary artery (LAD) was produced in dogs to reduce the reactive hyperemic response to <20%. Adenosine and CGS-21680 were then separately infused to maximize left circumflex coronary artery (LCx) flow velocity. (201)Tl (0.5 mCi) and (99m)Tc-sestamibi (5 mCi) were injected at the maximal dose of CGS-21680. Heart rate decreased with adenosine but increased during CGS-21680 infusion (P<0.005). The decrease in systolic blood pressure was more prominent with adenosine than with CGS-21680 (P<0.005). In the control LCx zone, maximal myocardial blood flow (MBF) (measured by radioactive microspheres) increased 3.1-fold during adenosine infusion (P<0.005) and 3.8-fold during CGS-21680 infusion (P<0.005). In the stenotic LAD zone, MBF did not change significantly. During adenosine and CGS-21680 infusion, stenosis/control zone MBF ratios were comparable (0.32+/-0.11 versus 0.27+/-0.10, P=NS), and transmural (201)Tl and (99m)Tc-sestamibi count-activity ratios (0.48+/-0.11 and 0.51+/-0.09, respectively) were also comparable (P=NS). Myocardial scintigraphy uncovered perfusion defects in all dogs. CGS-21680 elicits coronary vasodilation comparable to that of adenosine and produces profound heterogeneity of MBF and of (201)Tl and (99m)Tc-sestamibi myocardial uptake, rendering it a promising agent for pharmacological myocardial perfusion imaging.

Coronary artery flow velocity is related to lumen area and regional left ventricular mass.

Coronary flow velocity varies widely between individuals, even at rest. Because of this variation, indices with less apparent deviation, such as the ratio of hyperemic to resting velocity (coronary flow reserve), have been more commonly studied. We tested the hypothesis that the flow continuity principle could be used to model resting coronary flow, and we examined the resulting velocity relationship. We studied coronary velocity in 59 patients using a Doppler wire to measure resting and hyperemic average peak velocities in the left anterior descending artery. Quantitative techniques were used to calculate lumen cross-sectional area and the lengths of all distal coronary branches. Branch lengths were used to estimate regional left ventricular mass. We then calculated the ratio of lumen area to regional mass (A/m). Regional perfusion was estimated from the double product of heart rate and systolic blood pressure. Resting velocity (V) varied inversely with A/m ratio [V=46.5/(A/m); r=0.68, P<0.001]. Disease in the left anterior descending artery was categorized as none or luminal irregularities only (n=22), mild (n=15), or moderate (n=22). The A/m ratio declined across these groups (8.7+/-4.0, 8.5+/-6.2, and 5. 6+/-3.0 mm(2)/100 g, respectively; P<0.04), and the resting average peak velocity increased (27+/-16, 33+/-11, and 37+/-20 cm/s, respectively; P=0.06). Resting coronary artery flow velocity is inversely related to the ratio of lumen area to regional left ventricular mass. Higher resting velocities are found when insufficient lumen size exists for the distal myocardial bed, as occurs with diffuse mild or moderate coronary atherosclerosis.

Magnetic resonance coronary angiography in patients with ischemic heart disease: analysis of coronary arterial blood flow velocity pattern.

Only a few reports evaluating coronary arterial blood flow velocity patterns using magnetic resonance (MR) coronary angiography have appeared to date. This study reports an evaluation of coronary arterial blood flow velocity patterns in patients with ischemic heart disease and in healthy subjects using MR coronary angiography. The subjects consisted of 20 patients with ischemic heart disease (IHD group) and 20 normal healthy subjects (N group). Using the fCARD PC method, ECG-gated MR coronary angiography was performed using an anteroposterior opposing phased array coil. Regions of interest were placed on bilateral coronary arteries to measure coronary arterial blood flow velocity patterns. The IHD group was divided into two subgroups, based on the presence (MI group) or absence (AP group) of infarcted myocardium using 99m Tc-methoxyisobutylisonitrile (MIBI) myocardial scintigraphy. Average diastolic peak velocity (ADPV) was lower in the IHD group than in the N group. In addition, the diastolic / systolic velocity ratio (DSVR) was significantly lower in the MI group. Moreover, in the AP group, both the ADPV and DSVR values were significantly increased in those who had undergone percutaneous transluminal coronary angioplasty postoperatively. Different from the Doppler guidewire method, MR coronary angiography facilitates noninvasive evaluation of coronary arterial blood flow velocity. Therefore, these results indicate that MR coronary angiography represents a potentially useful technique for diagnosing lesions of coronary arteries and evaluating their functions. This noninvasive method can be expected to replace the invasive Doppler guidewire method in the near future with development of MR coronary angiography technology.

Effect of insulin resistance on the endothelial vasomotor function of the coronary artery of nondiabetic patients.

Attention has been paid to the relationship between insulin resistance and coronary artery disease. The present study investigated the relationship between insulin resistance and the endothelial vasomotor function of the coronary artery of nondiabetic patients with chest pain and a positive exercise tolerance test. Twenty-five nondiabetic patients with chest pain were included. Patients with a steady state plasma glucose (SSPG) level of greater than or equal to 135 mg/dl were placed in the insulin resistant (IR) group, and those with a SSPG level less than 135 mg/dl were placed in the noninsulin resistant (NIR) group. The effect of acetylcholine, papaverine, and isosorbide dinitrate on the vasomotor response of the coronary endothelium was studied. The percent change in diameter of the coronary artery after injection of acetylcholine (20 microg ml(-1) min(-1)) was 84+/-17% in the IR group, and 109+/-18% in the NIR group. The difference in the degree of the vasodilative response is statistically significant (p<0.01). The percent change in coronary flow velocity after injection of acetylcholine (20 microg ml(-1) min(-1)) in the IR group was 120+/-67%, whereas that in the NIR group was 256+/-58%; the increase in coronary artery flow velocity of the IR group was significantly smaller than that of the NIR group (p<0.01). Nondiabetic patients with insulin resistance have endothelial vasomotor dysfunction, which raises an important question as to whether nondiabetic patients with insulin resistance should be treated to prevent the development of coronary heart disease.

Chronic Decrease of Average Peak Flow Velocity in Coronary Arteries of Transplant Recipients

Chronic Decrease of Average Peak Flow Velocity in Coronary Arteries of Transplant Recipients

Transthoracic Doppler Echocardiography of Normally Originating Coronary Arteries in Children

Transthoracic Doppler color flow and spectral velocity patterns of normal coronary arteries in children have not been well studied. We designed this study to evaluate coronary artery flow velocity characteristics in normal and hypertrophied hearts. Sixty-eight children with optimal two-dimensional echocardiographic images of the left coronary artery (LCA) and right coronary artery (RCA) were prospectively studied. The heart was normal in 45 children, and 23 had left and/or right ventricular hypertrophy assessed by echocardiography (mean age 5.8 versus 5.2 years, p = NS). Color flow signals were detected in the LCA in 63(92%) of the 68 children studied, and pulsed Doppler spectral waveforms were recorded in 47 (69%). The latter were recorded in 26 (58%) of 45 normal children and in 21 (91%) of 23 children with left ventricular hypertrophy. Diastolic RCA flow signals were detected mostly in those with right ventricular hypertrophy (10 of 10). Higher levels of LCA maximum diastolic velocity (42 ± 23 versus 24 ± 6 cm/sec, p = 0.0004), increased diastolic flow (16 ± 15 versus 6 ± 4 ml/min, p = 0.01), and delayed time to peak diastolic velocity expressed as a percentage of diastolic spectral duration (38% ± 14% versus 20% ± 8%, p = 0.0001) were observed in children with left ventricular hypertrophy than in those in normal children. A strong correlation was present between Doppler-derived LCA flow and left ventricular mass/m 2 ( r = 0.7, p = 0.001). In normal hearts, LCA spectral velocity pattern did not change with increasing age, but the time velocity integral became progressively larger, resulting in a strong correlation with weight ( p < 0.001, r = 0.78). This study demonstrates (1) LCA flow signals can be detected and quantitated in the majority of children with and those without left ventricular hypertrophy. (2) Left ventricular hypertrophy is associated with increased LCA flow, higher diastolic velocity, and delayed peak diastolic velocity. (3) RCA flow signals are mostly detected when there is right ventricular hypertrophy. Studies on larger groups of patients are needed to further confirm our observations and to enhance understanding of coronary artery flow reserve. (J Am Soc Echocardiogr 1998;11:409-20.)

Oxygen-derived free radicals contribute to neural stunning in the canine heart.

Oxygen-derived free radicals (ODFR) contribute to delayed recovery of myocardial function after brief ischemia. We examined the effect of ODFR scavengers on ischemia-induced dysfunction of cardiac sympathetic nerves. Mongrel dogs were anesthetized and instrumented for recording heart rate, arterial pressure, systolic wall thickening, and left anterior descending coronary artery (LAD) and left circumflex coronary artery (LCX) flow velocities. Bilateral stellate stimulation was performed, measuring changes in an index of coronary vascular resistance (% delta CVR) before and after 15 min of LAD occlusion. Superoxide dismutase (SOD) and catalase (CAT) were infused intravenously for 30 min beginning 10 min before occlusion. With vehicle (n = 13), % delta CVR was significantly attenuated in LAD after ischemia and 30-min reperfusion [39 +/- 3 to 13 +/- 2%, P < 0.05; for LCX, 42 +/- 4 to 45 +/- 7%, P = not significant (NS)]; however, no attenuation was seen in dogs in which SOD and CAT were infused (n = 10; for LAD, 39 +/- 5 to 41 +/- 5%; for LCX, 46 +/- 7 to 47 +/- 6%; P = NS). Baseline and stimulated changes in hemodynamics were similar between groups. The % delta CVR in the LCX (control) bed was not affected by SOD and CAT. Recovery of myocardial function (percent of baseline) was greater in SOD and CAT after reperfusion (26 +/- 16% vs. -30 +/- 11% at 90 min of reperfusion, P < 0.05). We conclude that ODFR contribute not only to myocardial stunning but also to neural stunning of sympathetic cardiac innervation after brief ischemia.

Assessment of stenosis severity using a novel method to estimate spatial and temporal variations of blood flow velocity in biplane coronarography

The authors present a novel method to estimate absolute blood flow velocity in coronary arteries from biplane angiograms. Spatial and temporal velocity variations are derived giving simultaneously a direct geometric and an indirect functional index of stenosis severity, stenosis ratio and coronary flow reserve. No prior assumption concerning stenosis geometry is made. Deformable models are used to track a coronary artery segment dynamically in three dimensions. A densitometric map is obtained by summing densities across sections at every position along the previously calculated path and at every time of the cardiac cycle. An advection relationship between density and velocity is observed. The spatiotemporal velocity map is a solution of a nonlinear least-squares scheme. A simulation protocol based on simple geometric conformations and blood flow properties is used to assess numerical stability and immunity towards noise. Predicted results for temporal velocity variations are compared with the intracoronary Doppler recordings to test the model assumptions for basal state and hyperaemia examinations of the same patient. The stenosis ratio was accurate to within 3% for a simulated additive Gaussian noise with a standard deviation of 0.14. The limits of agreement between angiographic and Doppler velocities were -11.4 and for a peak value of (basal state) and -16.8 and for a peak value of (hyperaemia), corresponding to 18 and 3.5% errors on the average peak values and a 16% error on the coronary flow reserve. To summarize, the advection model derivation and its solution are presented. Simulated and experimental results corroborate the validity of the numerical schemes and support clinical applicability.

Multiple coronary artery-left ventricular fistulae: haemodynamic quantification by intracoronary Doppler ultrasound.

Multiple coronary artery-left ventricular fistulae involving all three major coronary arteries are extremely rare. Clinical findings are heterogeneous but include a history of typical or atypical angina pectoris in most...