The Effect of Aortic Valve Replacement on Coronary Flow Reserve in Patients with a Normal Coronary Angiogram

Background: In patients with aortic stenosis and a normal coronary angiogram, a coronary flow reserve (CFR) is impaired. The aim of the present study was to examine the effect of aortic valve replacement (AVR) on the CFR after a long-term follow-up. Patients and Methods: 30 patients with aortic stenosis and a normal coronary angiogram were enrolled in the study. CFR measurements were made on 21 patients 123 - 137 days before and 497 - 167 days after AVR. CFR measurements were carried out according to a standard protocol, with a vasodilator stimulus dipyridamole (0.56 mg/kg for 4 min) and peak diastolic velocity measurements at 6 min. Results: Initially, the average peak gradient of aortic stenosis was 89.5 - 22.4 mm Hg. After AVR, it decreased to 26.2 - 9 mm Hg. Left ventricular mass was significantly lower after AVR: 354.9 - 107.9 g versus 223.8 - 73.6 g (p < 0.001). The average baseline diastolic velocity measured by pulsed Doppler in the left anterior descending coronary artery amounted to 62.2 - 25.5 cm/s before and 40.1 - 13.6 cm/s after AVR. The difference was statistically significant (p < 0.01). The average diastolic velocity at maximum stress equaled 117 - 42.8 cm/s pre- and 91.5 - 34 cm/s postoperatively (p < 0.005). The calculated CFR before AVR amounted to 1.96 - 0.5 and increased to 2.37 - 0.8 postoperatively. The difference was statistically significant (p < 0.05). Conclusion: Prosthetic AVR is of considerable benefit concerning the CFR in patients with a normal coronary angiogram after a long-term follow-up. Hintergrund: Bei Patienten mit Aortenklappenstenose und anatomisch normalem Koronarsystem ist die Koronarflussreserve (CFR) vermindert. Ziel dieser Studie war, die Auswirkungen von Aortenklappenersatzoperationen (AVR) auf die CFR im Langzeitverlauf zu untersuchen. Patienten und Methodik: 30 Patienten mit Aortenklappenstenose wurden in die Studie einbezogen. Die CFR wurde bei 21 Patienten 123 - 137 Tage vor und 497 - 167 Tage nach AVR mit einer standardisierten echokardiographischen Methode transösophageal bestimmt. Die Doppler-Messungen erfolgten im Normalzustand und nach maximaler Vasodilatation durch 4-min-Infusion von 0,56 mg/kg Dipyridamol. Ergebnisse: Der durchschnittliche Druckgradient über den Aortenklappen lag bei 89,5 - 22,4 mm Hg vor und 26,2 - 9 mm Hg nach AVR. Das linksventrikuläre Gewicht war nach der Operation signifikant vermindert (354,9 - 107,9 vs. 223,8 - 73,6 g; p < 0.001). Die durchschnittliche diastolische Geschwindigkeit in den Ramus-interventricularis-anterior-Arterien lag präoperativ bei 62,2 - 25,5 cm/s und postoperativ bei 40,1 - 13,6 cm/s (p < 0.01). Die durchschnittliche diastolische Geschwindigkeit bei maximaler Vasodilatation betrug 117 - 42,8 cm/s vor und 91,5 - 34 cm/s nach AVR (p < 0.05). Der kalkulierte CFR-Wert lag präoperativ bei 1,96 - 0,5 und erhöhte sich nach der Operation auf 2,37 - 0,8 (p < 0,05). Schlussfolgerung: Die Implantation von Aortenklappenprothesen hat eine positive Wirkung auf die CFR von Patienten mit anatomisch normalen Koronararterien.     

Coronary flow reserve improves after aortic valve replacement for aortic stenosis: an adenosine transthoracic echocardiography study

OBJECTIVES: The goal of this study was to assess coronary flow reserve (CFR) before and after aortic valve replacement (AVR). BACKGROUND: Coronary flow reserve is impaired under conditions of left ventricular (LV) hypertrophy. It is not known whether CFR improves with regression of LV hypertrophy in humans. METHODS: We investigated 35 patients with pure aortic stenosis, LV hypertrophy and normal coronary arteriograms. Patients underwent adenosine transthoracic echocardiography on two occasions--immediately before AVR and six months postoperatively. Left ventricular mass, distal left anterior descending coronary artery (LAD) diameter, flow and CFR were assessed on each occasion. RESULTS: Distal LAD diameter was successfully imaged in 30 patients (86%), and blood flow was successfully imaged in 27 (77%). Paired data were subsequently available in 24 patients, of whom 14 were men, mean age 68.1+/-12.5 years, body mass index 24.5+/-2.0 kg/m2, aortic valve gradient 93+/-32 mm Hg. Pre- to post-AVR a significant decrease was seen in LV mass (271+/-38 vs. 236+/-32g, p<0.01) and LV mass index (154+/-21 vs. 134+/-21 g/m2, p< 0.01). Distal LAD diameter fell from 2.27+/-0.37 to 2.23+/-0.35 mm, p = 0.08). Pre- to post-AVR there was no significant change in resting parameters of peak diastolic velocity (0.43+/-0.16 vs. 0.41+/-0.11 m/s), distal LAD flow 23.3+/-10.1 vs. 20.9+/-5.2 ml/min or distal LAD flow scaled for LV mass (8.7+/-3.8 vs. 9.0+/-2.5 ml/min/100 g LV mass), but there was significant increase in hyperemic peak diastolic velocity (0.71+/-0.26 vs. 1.08+/-0.24 m/s; p<0.01), distal LAD flow (37.8+/-11.3 vs. 53.5+/-16.1 ml/min; p<0.01) and distal LAD flow scaled for LV mass (14.3+/-5.0 vs. 23.3+/-8.5 ml/min/100 g LV mass; p<0.01). Coronary flow reserve, therefore, increased from 1.76+/-0.5 to 2.61+/-0.7. CONCLUSIONS: Coronary flow reserve increases after AVR for aortic stenosis. This increase occurs in tandem with regression of LV hypertrophy.     

Impact of patient-prosthesis mismatch and aortic valve design on coronary flow reserve after aortic valve replacement.

OBJECTIVES: This prospective-randomized study investigated the effect of aortic valve design and patient-prosthesis mismatch (PPM) on coronary flow reserve (CFR) after mechanical or biological aortic valve replacement (AVR) in patients with aortic stenosis (AS). BACKGROUND: Coronary flow reserve may be an important parameter of long-term survival after AVR in patients with AS. Reduced CFR may contribute to more cardiovascular events and greater rates of mortality. METHODS: A total of 48 patients undergoing AVR underwent magnetic resonance imaging for the measurement of coronary flow preoperatively, 5 days postoperatively, and at 6-month follow-up with measurement of CFR. Patients scheduled for mechanical AVR were randomized to a tilting disc or bileaflet prosthesis (n = 12 in each group). For biological AVR, patients were scheduled to receive a stented (n = 12) or stentless (n = 12) valve. Patients also underwent echocardiography with measurement of transvalvular pressure gradients and left ventricular mass regression. RESULTS: Postoperatively, coronary flow increased significantly in all groups (p < 0.001). Only stentless valves demonstrated a normal CFR (3.4 +/- 0.3 vs. 2.3 +/- 0.1 for stented biological valves, 2.1 +/- 0.2 for tilting disc, and 2.2 +/- 0.3 for bileaflet mechanical valves). Patient-prosthesis mismatch with an indexed effective orifice area <0.85 cm2/m2 led to decreased rates of CFR in the tilting disc, stentless, and stented groups. Pressure gradients were 14 +/- 3 mm Hg for tilting disc, 12 +/- 4 mm Hg for bileaflet, 19 +/- 6 mm Hg for stented, and 10 +/- 4 mm Hg for stentless valves. CONCLUSIONS: Normalization of CFR after AVR in patients with AS was observed only for stentless valves. Coronary flow reserve might explain the excellent long-term results for stentless valves. (Impact of Patient-Prosthesis Mismatch on Coronary Flow Reserve; http://www.clinicaltrials.gov/ct/show/NCT00310947?order=1; NCT00310947).     

Alterations of phasic coronary artery flow velocity in humans during percutaneous coronary angioplasty.

BACKGROUND AND OBJECTIVES. Studies using Doppler catheters to assess blood flow velocity and vasodilator reserve in proximal coronary arteries have failed to demonstrate significant improvement immediately after coronary angioplasty. Measurement of blood flow velocity, flow reserve and phasic diastolic/systolic velocity ratio performed distal to a coronary stenosis may provide important information concerning the physiologic significance of coronary artery stenosis. This study was designed to measure these blood flow velocity variables both proximal and distal to a significant coronary artery stenosis in patients undergoing coronary angioplasty. METHODS. A low profile (0.018-in.) (0.046-cm) Doppler angioplasty guide wire capable of providing spectral flow velocity data was used to measure blood flow velocity, flow reserve and diastolic/systolic velocity ratio both proximal and distal to left anterior descending or left circumflex coronary artery stenosis. These measurements were made in 38 patients undergoing coronary angioplasty and in 12 patients without significant coronary artery disease. RESULTS. Significant improvement in mean time average peak velocity was noted in distal coronary arteries after angioplasty (before 19 +/- 12 cm/s; after 35 +/- 16 cm/s; p less than 0.01). Increases in proximal average peak velocity after angioplasty were less remarkable (before 34 +/- 18 cm/s; after 41 +/- 14 cm/s; p = 0.04). Mean flow reserve remained unchanged after angioplasty both proximal (1.5 +/- 0.5 vs. 1.6 +/- 1; p greater than 0.10) and distal (1.6 +/- 1 vs. 1.5 +/- 0.8; p greater than 0.10) to a coronary stenosis. Before angioplasty, mean diastolic/systolic velocity ratio measured distal to a significant stenosis was decreased compared with that in normal vessels (1.3 +/- 0.5 vs. 1.8 +/- 0.5; p less than 0.01). After angioplasty, distal abnormal phasic velocity patterns generally returned to normal, with a significant increase in mean diastolic/systolic velocity ratio (1.3 +/- 0.5 vs. 1.9 +/- 0.6; p less than 0.01). Phasic velocity patterns and mean diastolic/systolic velocity ratio measured proximal to a coronary stenosis were not statistically different from values in normal vessels (1.8 +/- 0.8 vs. 1.8 +/- 0.5; p greater than 0.10) and did not change significantly after angioplasty (1.8 +/- 0.8 vs. 2.13 +/- 0.9; p greater than 0.10). CONCLUSIONS. Flow velocity measurements may be performed distal to a coronary stenosis with the Doppler guide wire. Phasic velocity measurements made proximal to a coronary stenosis differed from those in the distal coronary artery. Both proximal and distal flow reserve measurements made immediately after angioplasty were of limited utility. Changes in distal flow velocity patterns and diastolic/systolic velocity ratio appeared to be more relevant than the hyperemic response in assessing the immediate physiologic outcome of coronary angioplasty.     

Is the coronary flow velocity reserve improvement after aortic valve replacement for aortic stenosis transient? Results of a 3-year follow-up

The coronary flow velocity reserve (CFR) is decreased in patients with aortic valve stenosis (AS). The aim of the present prospective study was to examine the CFR in AS patients with normal epicardial coronary arteries during a 3-year follow-up of aortic valve replacement (AVR). A total of 30 AS patients (17 women and 13 men) were enrolled in this prospective follow-up study; they all had a normal coronary angiogram and underwent dipyridamole stress transesophageal echocardiography (STEE) for CFR measurement before AVR. Nine of them participated in this 3-year follow-up study, and all patients were examined 16 months and 3 years after AVR by STEE. The CFR of AS patients was decreased before AVR. Different extents of diastolic coronary flow velocity reduction (resting and posthyperaemic) were observed resulting in a significant CFR improvement, despite the low number of patients during the 16-month follow-up. A further posthyperemic flow velocity reduction was demonstrated after the 3-yearfollow-up, resulting in a significant CFR impairment. The CFR decreased in 5 cases, but remained practically unchanged in 3 after the first CFR measurement; only the CFR of 1 patient improved minimally. The main finding of the current study is that the CFR improvement 16 months after AVR, which paralleled the regression of the left ventricular hypertrophy, was found to be transient. Coronary flow velocity reserve impairment was demonstrated after the long-term (3-year) follow-up in most of the patients, which could not be explained by extravascular compressive forces. The topic of this paper was presented at the European Society of Cardiology Congress 2004, Munich, Germany     

Diminished coronary flow velocity reserve and aortic distensibility in elderly patients with chest pain and negative coronary angiograms

BACKGROUND AND AIMS: Aging is a dominant process that alters vascular stiffness, endothelial function and coronary flow regulation. The objective of our work was to assess simultaneously the elastic properties of the descending aorta and coronary flow velocity reserve (CFR) during the same transesophageal echocardiography (TEE) in elderly patients. METHODS: The following patients with normal epicardial coronary arteries were compared: 30 subjects under 55 years of age (group 1) and 17 patients over 55 years (group 2). A complete TEE examination was carried out in all patients, and the following aortic elastic properties were calculated from aortic diameter and blood pressure data: aortic elastic modulus [E(p)] and Young's circumferential static elastic modulus [E(s)]. Doppler evaluation of left anterior descending coronary flow velocity was performed in resting conditions and after administration of 0.56 mg/Kg dipyridamole over 4 min. Peak coronary flow velocities were measured at the 6th minute at maximum vasodilation. CFR was estimated as the ratio of hyperemic to basal peak diastolic coronary flow velocities. RESULTS: Peak hyperemic diastolic coronary flow velocities were significantly decreased (139.1+/-35.6 cm/s vs 105.7+/-39.7 cm/s, p<0.01) in patients >55 years. CFR was decreased (2.67+/-1.05 vs 2.13+/-0.56, p<0.05), whereas E(p) (in 103 mmHg, 0.59+/-0.49 vs 0.94+/-0.65, p<0.05) and E(s) (in 103 mmHg, 5.70+/-4.30 vs 8.47+/-5.14, p<0.05) were increased in patients >55 years. A correlation was found between CFR and E(p) (r=-0.20, p<0.05). CONCLUSIONS: CFR and aortic distensibility are altered in elderly patients. There is a relationship between these functional parameters.     

Left ventricular remodeling early after aortic valve replacement: differential effects on diastolic function in aortic valve stenosis and aortic regurgitation

OBJECTIVES: The aim of this study was to evaluate the effect of aortic valve replacement (AVR) on left ventricular (LV) function and LV remodeling, comparing patients with aortic valve stenosis to patients with aortic regurgitation. BACKGROUND: Aortic valve disease is associated with eccentric or concentric LV hypertrophy and changes in LV function. The relationship between LV geometry and LV function and the effect of LV remodeling after AVR on diastolic filling, in patients with aortic valve stenosis compared with aortic regurgitation, are largely unknown.Nineteen patients with aortic valve disease (12 aortic valve stenosis, 7 aortic regurgitation) were studied using magnetic resonance imaging to assess LV geometry and LV function before and 9 +/- 3 months after AVR. Ten age-matched healthy males served as control subjects. RESULTS: Before AVR, the ratio between left ventricular mass index (LVMI) and left ventricular end-diastolic volume index (LVEDVI) was only increased in patients with aortic valve stenosis (1.37 +/- 0.16 g/ml) compared with control subjects (0.93 +/- 0.08 g/ml, p < 0.05). After AVR, LVMI/LVEDVI decreased significantly in aortic valve stenosis (to 1.15 +/- 0.14 g/ml, p < 0.0001), but increased significantly in aortic regurgitation (1.02 +/- 0.20 g/ml to 1.44 +/- 0.27 g/ml, p < 0.0001). Before AVR, diastolic filling was impaired in both aortic valve stenosis and aortic regurgitation. Early after AVR, diastolic filling improved in patients with aortic valve stenosis, whereas patients with aortic regurgitation showed a deterioration in diastolic filling. CONCLUSIONS: Early after AVR, patients with aortic valve stenosis show a decrease in both LVMI and LVMI/LVEDVI and an improvement in diastolic filling, whereas in patients with aortic regurgitation, LVMI decreases less rapidly than LVEDVI, causing concentric remodeling of the LV, most likely explaining the observed deterioration of diastolic filling in these patients.     

Simultaneous Improvement in Aortic Distensibility and Coronary Flow Velocity Reserve after Successful Coronary Interventions

Objective: Deteriorations in coronary flow velocity reserve (CFR) and aortic distensibility have been demonstrated in coronary artery disease. The objective of the present study was a simultaneous echocardiographic evaluation of the CFR and aortic distensibility indices before and after successful percutaneous coronary interventions (PCI) in patients with left anterior descending coronary artery (LAD) disease. Methods: The study population, comprising 12 patients (4 women and 8 men) with significant proximal LAD stenosis, were compared with matched controls. Transesophageal echocardiography (TEE) was carried out to evaluate the CFR and aortic distensibility indices (the aortic elastic modulus E(p) and Young's circumferential static elastic modulus E(s)) before and after PCI to the LAD. The subjects underwent TEE on average 8 ± 11 days before PCI and 25 ± 6 weeks after PCI. Results: An improvement in CFR was demonstrated in patients with LAD stenosis after successful PCI (1.71 ± 0.36 vs. 2.08 ± 0.28, P < 0.05), which paralleled the decreases in E(p) (936 ± 544 mmHg vs. 567 ± 184 mmHg, P < 0.05) and E(s) (10,207 ± 6,295 mmHg vs. 5,831 ± 2,010 mmHg, P < 0.05) during the follow‐up. Conclusion: The aortic distensibility improves in parallel with the increase in CFR in patients with LAD stenosis after successful PCI. (Echocardiography 2010;27:311‐316)     

Coronary flow reserve is impaired in patients with slow coronary flow

BACKGROUND: Slow coronary flow (SCF) in a normal coronary angiogram is a well-recognized clinical entity, but its etiopathogenesis remains unclear. However, previous studies have suggested that microvascular abnormalities and endothelial dysfunction responsible for SCF. Accordingly, we hypothesized that SCF phenomenon may be a form, at least early phase, of atherosclerosis that involve both small vessels and epicardial coronary arteries, and therefore we investigated coronary flow reserve (CFR) reflecting coronary microvascular function in patients with SCF. METHODS: Twenty subjects with SCF and 15 control subjects with normal coronary flow were studied. Coronary flow was quantified according to TIMI frame count (TFC). Coronary diastolic peak flow velocities were measured at baseline and after dipyridamole infusion. CFR was calculated as the ratio of hyperemic to baseline diastolic peak velocities. RESULTS: Demographic features, coronary risk factors, echocardiographic measurements except diastolic function parameters, and biochemical measurements were similar between the groups. CFR values were significantly lower in subjects with SCF than in the control group (1.99+/-0.38 versus 2.99+/-0.47, P<0.0001). In addition, TIMI frame count independently correlated with CFR. CONCLUSION: These findings suggest that CFR, which reflects coronary microvascular function, is impaired in patients with SCF, and corrected TFC well correlates with CFR.     

Assessment of flow velocity reserve by transthoracic Doppler echocardiography and venous adenosine infusion before and after left anterior descending coronary artery stenting.

OBJECTIVES: We sought to evaluate whether coronary flow velocity reserve (CFR) (the ratio between hyperemic and baseline peak flow velocity), as measured by transthoracic Doppler echocardiography during adenosine infusion, allows detection of flow changes in the left anterior descending coronary artery (LAD) before and after stenting. BACKGROUND: The immediate post-stenting evaluation of CFR by intracoronary Doppler has shown mixed results, due to reactive hyperemia and microvascular stunning. Noninvasive coronary Doppler echocardiography may be a more reliable measure than intracoronary Doppler. METHODS: Transthoracic Doppler echocardiography during 90-s venous adenosine infusion (140 microg/kg body weight per min) was used to measure CFR of the LAD in 45 patients before and 3.7 +/- 2 days after successful stenting, as well as in 25 subjects with an angiographically normal LAD (control group). RESULTS: Adequate Doppler spectra were obtained in 96% of the patients. Pre-stent CFR was significantly lower in patients than in control subjects (diastolic CFR: 1.45 +/- 0.5 vs. 2.72 +/- 0.71, p < 0.01; systolic CFR: 1.61 +/- 1.02 vs. 2.41 +/- 0.68, p < 0.01) and increased toward the normal range after stenting (diastolic CFR: 2.58 +/- 0.7 vs. 2.72 +/- 0.75, p = NS; systolic CFR: 2.43 +/- 1.01 vs. 2.41 +/- 0.52, p = NS). Diastolic CFR was often damped, suggesting coronary steal in patients with > or =90% versus <90% LAD stenosis (0.86 +/- 0.23 vs. 1.69 +/- 0.43, p < 0.01). Coronary stenting normalized diastolic CFR in these two groups (2.45 +/- 0.77 and 2.64 +/- 0.69, respectively, p = NS), even though impaired diastolic CFR persisted in three of four patients with > or =90% stenosis. Stenosis of the LAD was better discriminated by diastolic (F = 49.30) than systolic (F = 12.20) CFR (both p < 0.01). CONCLUSIONS: Coronary flow reserve, as measured by transthoracic Doppler echocardiography, is impaired in LAD disease; it may identify patients with > or =90% stenosis; and it normalizes early after stenting, even in patients with > or =90% stenosis.     

Non-invasive assessment of coronary flow reserve in idiopathic dilated cardiomyopathy: hemodynamic correlations.

BACKGROUND: Impaired vasodilator myocardial blood flow response has been observed in dilated cardiomyopathy (DCMP). However, the mechanisms responsible for this blunted response are not clear. In the present study, we investigated whether the blunted vasodilator flow response is related to indices of left ventricular performance in patients with idiopathic dilated cardiomyopathy. METHODS AND RESULTS: Eighteen DCMP patients and 12 healthy subjects (C) underwent transoesophageal echocardiography within 48 h from cardiac catheterization. Coronary flow velocity reserve (CFR) was measured in the proximal LAD as the ratio of the peak diastolic coronary flow velocity (Vd-M) after intravenous administration of adenosine to peak baseline diastolic flow velocity (Vd-R). Left ventricular (LV) mass index was positively correlated with baseline coronary diastolic velocity (r=0.415; p=0.043) and inversely correlated with coronary flow reserve (r=-0.570; p=0.003). The baseline coronary diastolic velocity was higher in DCMP vs C (56+/-13 cm/s vs 35+/-12 cm/s; p=0.04). In DCMP pts Vd-R positively correlated with end-diastolic wall stress (r=0.654; p=0.01). Vd increased in both C (96+/-32 cm/s; p<0.05 vs baseline) and DCMP patients (108+/-20 cm/s; p<0.01 vs baseline). The CFR was lower in DCMP patients vs C (1.93+/-0.78 vs 2.99+/-1.01; p=0.009). In DCMP pts CFR was negatively correlated with right atrial pressure (r=-0.595; p=0.015), LVEDP (r=-0.576; p=0.015), pulmonary capillary wedge pressure (PCWP: r=-0.772; p<0.001) and positively with ejection fraction (EF: r=0.683; p=0.003). CONCLUSION: Pts with DCMP have lower CFR compared to controls. This blunted CFR is due to higher baseline coronary flow and reflects higher wall stress. The close relation between CFR and EF, PCWP and LVEDP suggests that not only a higher baseline Vd but also compressive forces due to left ventricular dysfunction might be responsible for the observed blunted adenosine-mediated coronary vasodilation.     

Role of variability in microvascular resistance on fractional flow reserve and coronary blood flow velocity reserve in intermediate coronary lesions

BACKGROUND: Fractional flow reserve (FFR) and coronary blood flow velocity reserve (CFR) represent physiological quantities used to evaluate coronary lesion severity and to make clinical decisions. A comparison between the outcomes of both diagnostic techniques has not been performed in a large cohort of patients with intermediate coronary lesions. METHODS AND RESULTS: FFR and CFR were assessed in 126 consecutive patients with 150 intermediate coronary lesions (between 40% and 70% diameter stenosis by visual assessment). Agreement between outcomes of FFR and CFR, categorized at cut-off values of 0.75 and 2.0, respectively, was observed in 109 coronary lesions (73%), whereas discordant outcomes were present in 41 lesions (27%). In 26 of these 41 lesions, FFR was <0.75 and CFR>or=2.0 (group A); in the remaining 15 lesions, FFR was >or=0.75 and CFR<2.0 (group B). Minimum microvascular resistance, defined as the ratio of mean distal pressure to average peak blood flow velocity during maximum hyperemia, showed a large variability (overall range, 0.65 to 4.64 mm Hg x cm(-1) x s(-1)) and was significantly higher in group B than in group A (2.42+/-0.77 versus 1.91+/-0.70 mm Hg x cm(-1) x s(-1); P:=0.034). CONCLUSIONS: Our findings demonstrate the prominent role of microvascular resistance in modulating the relationship between FFR and CFR and emphasize the importance of combined pressure and flow velocity measurements to evaluate coronary lesion severity and microvascular involvement.     

Measuring blood flow velocity in the coronary sinus with Doppler catheters]

Measurements of the coronary sinus blood flow velocity with Doppler catheters (Medtronic Floscan; Millar DC201) were performed to assess coronary flow reserve and significance of coronary artery stenosis. In seven patients with normal coronary angiogram coronary sinus blood flow velocity (Doppler catheters) and coronary sinus blood flow volume (thermodilution) were simultaneously recorded. Coronary flow reserve was calculated as the quotient of the peak flow velocity (peak flow volume) and resting flow velocity (resting flow volume) after infusion of 0.5 mg/kg dipyridamole intravenously. The correlation coefficient was r = 0.88. Coronary sinus blood flow velocity was measured in 31 patients at resting conditions and after injection of contrast media during coronary angiography. At resting conditions blood flow velocity was 3.6 +/- 1.5 cm/s (n = 31), 3.5 +/- 1.8 cm/s (n = 9; controls), and 3.6 +/- 1.1 cm/s (n = 9; significant stenosis of the left anterior descending; not significant). After injection of contrast media flow velocity amounted to 2.2-fold resting flow in controls and to 1.5-fold resting flow in patients with stenoses of the left anterior descending artery (p less than 0.01). Measurement of coronary sinus blood flow velocity with Doppler catheters is a valuable adjunct for determination of coronary flow reserve and for assessment of stenosis severity of the left anterior descending artery. Continuous on-line monitoring of phasic flow velocity provides important information of the myocardial perfusion, e.g., during angioplasty.     

Doppler echocardiographic evaluation of left ventricular diastolic filling in isolated valvular aortic stenosis

Doppler echocardiography was used to study left ventricular (LV) diastolic filling in 49 adults with isolated aortic stenosis (AS), selected from 155 consecutive patients with AS by excluding coexisting mitral disease (n = 41) and/or significant aortic regurgitation (n = 80). There were no differences between patients with AS and age-matched normal subjects for early diastolic filling (E) velocity (68 +/- 17 vs 67 +/- 13 cm/s), late diastolic filling (A) velocity (79 +/- 25 vs 67 +/- 21 cm/s), E/A ratio (1.00 +/- 0.78 vs 1.06 +/- 0.32) or early diastolic deceleration slope (264 +/- 151 vs 319 +/- 137 cm/s2, differences not significant for all). There was no correlation between any LV filling parameter and AS severity, but late diastolic filling velocity was higher in patients with AS who had LV hypertrophy (n = 33) vs those who did not (n = 16) (86 +/- 23 vs 65 +/- 26 cm/s, p less than 0.01). In the patients with AS and systolic dysfunction (LV ejection fraction less than 50%) (n = 6), early diastolic filling velocity was higher (88 +/- 20 vs 65 +/- 15 cm/s, p less than 0.01), late diastolic filling velocity lower (53 +/- 23 vs 83 +/- 23 cm/s, p less than 0.01), E/A ratio higher (2.20 +/- 1.80 vs 0.84 +/- 0.28, p less than 0.01), deceleration slope steeper (439 +/- 230 vs 240 +/- 121 cm/s2, p = 0.02) and LV end-diastolic pressure higher (23 +/- 9 vs 10 +/- 6 mm Hg, p less than 0.01) than in patients with AS and normal systolic function.(ABSTRACT TRUNCATED AT 250 WORDS)     

Decreased aortic distensibility and coronary flow velocity reserve in patients with significant aortic valve stenosis with normal epicardial coronary arteries

BACKGROUND AND AIM OF THE STUDY: A number of clinical and experimental studies have suggested that aortic valve stenosis (AS) is a manifestation of atherosclerotic process. Previous studies have revealed a decreased coronary flow velocity reserve (CFR) in AS patients in consequence of left ventricular hypertrophy. The hypothesis was tested that the elastic properties of the descending aorta of AS patients might indicate signs of stiffness of the aorta. METHODS: The CFR and indices of aortic distensibility as functional markers of the descending aorta were compared in three different patient populations: (i) control subjects without valvular and coronary artery disease; (ii) patients with AS with normal epicardial coronary arteries; and (iii) patients with significant left anterior descending coronary artery (LAD) stenosis. CFR measurements were carried out according to a standard protocol, using vasodilatory stimulation with dipyridamole (0.56 mg/kg for 4 min), and peak diastolic velocity measurements at 6 min. The elastic properties of the aorta were calculated from echocardiographic parameters and blood pressure data. RESULTS: The CFR in AS patients was decreased to a similar extent as in patients with LAD stenosis. The aortic distensibility indices were similarly significantly increased in patients with AS and normal epicardial coronary arteries and with LAD stenosis, as compared with controls. CONCLUSION: These results indicate that the descending aorta exhibits appreciable increased stiffness in AS patients with normal epicardial coronary arteries.     

Coronary hemodynamics of stent implantation after suboptimal and optimal balloon angioplasty

OBJECTIVES: This study was performed to evaluate hemodynamic alterations of stent implantation after Doppler flow-guided balloon angioplasty (BA). BACKGROUND: There is controversy regarding the effect of stent implantation on coronary hemodynamics after suboptimal and optimal BA. METHODS: A total of 523 of 620 patients underwent Doppler-guided BA in the setting of a multicenter study and were analyzed before and after additional stent implantation. Balloon angioplasty was considered optimal when the diameter stenosis (DS) was < or = 35% and coronary flow reserve (CFR) was >2.5 and suboptimal if these two criteria were not met. Coronary flow reserve was also measured in an angiographically normal artery to determine relative CFR. Patients were followed for 12 months to document major adverse cardiac events (MACE). RESULTS: The main difference between patients with suboptimal BA (n = 195 [51%]) and optimal BA (n = 184 [49%]) was a more pronounced increase in baseline blood flow velocity (15 +/- 8 to 22 +/- 11 vs. 14 +/- 8 to 16 +/- 10 cm/s, p < 0.01). Coronary flow reserve improved after stent implantation in both patient groups, owing to a reduction in residual lumen obstruction, as determined by angiographic (%DS) and Doppler flow criteria (hyperemic blood flow velocity, relative CFR), and was associated with a decrease in MACE (16% vs. 7% in optimal BA group, p = 0.08; and 27% vs. 11% in suboptimal BA group, p = 0.007). CONCLUSIONS: Stent implantation enhances CFR after suboptimal and optimal Doppler-guided BA, owing to a reduction in residual lumen obstruction-determined by angiographical and Doppler flow criteria-as the underlying mechanism for an improved clinical outcome.     

Influence of alteration in preload on the pattern of left ventricular diastolic filling as assessed by Doppler echocardiography in humans

We examined the influence of alterations in preload on pulsed Doppler indexes of left ventricular diastolic function in 50 patients including 12 without cardiovascular disease, 29 with coronary artery disease, and nine with critical aortic stenosis. Micromanometer left ventricular pressure was recorded simultaneously with pulsed Doppler echocardiography of left ventricular inflow and M-mode echocardiography of left ventricular diameter. Chamber stiffness constants, kd and kv, were obtained from the diastolic pressure-diameter and pressure-volume relations, respectively. Relaxation was measured by the isovolumic relaxation time constants, TL and TD, derived from the exponential left ventricular pressure decay and maximum negative dP/dt. In 41 patients after nitroglycerin treatment, left ventricular end-diastolic pressure decreased from 18 +/- 5 to 13 +/- 4 mm Hg (p less than 0.001). The ratio of peak early to peak atrial filling velocities and time-velocity integral ratios decreased from 1.08 +/- 0.57 to 0.90 +/- 0.42 (p less than 0.001) and from 1.77 +/- 0.95 to 1.41 +/- 0.71 (p less than 0.001), respectively. The peak early filling velocity and time-velocity integral decreased from 56.1 +/- 15.7 to 49.9 +/- 14.5 cm/sec (p less than 0.001) and from 7.9 +/- 2.7 to 6.8 +/- 2.8 cm (p less than 0.001), respectively. Relaxation (TL, TD, and maximum negative dP/dt) and chamber stiffness (kd and kv) were not impaired after nitroglycerin administration. In 48 patients after ventriculography, left ventricular end-diastolic pressure increased from 18 +/- 6 to 22 +/- 8 mm Hg (p less than 0.001). The peak early and peak atrial filling velocities increased from 57.4 +/- 15.2 to 68.3 +/- 19.7 cm/sec (p less than 0.001) and from 61.0 +/- 22.7 to 69.4 +/- 23.2 cm/sec (p less than 0.01), respectively. As a result, the ratio of peak early to peak atrial filling velocity was unchanged. However, in the aortic stenosis group, the ratio of peak early to peak atrial filling velocity increased from 0.95 +/- 0.64 to 1.10 +/- 0.72 (p less than 0.02). Relaxation and chamber stiffness were unchanged. Thus, a reduction or increase in preload may induce a diastolic filling pattern that mimics or masks diastolic dysfunction, respectively. Preload conditions need to be accounted for when the status of diastolic function is extrapolated from the pulsed Doppler mitral inflow velocity profile.     

Coronary flow velocity reserve and indices describing aortic distensibility in patients after coronary angiography

BACKGROUND: The purpose of this study was to assess the elastic properties of the descending aorta and the coronary flow velocity reserve (CFR) in patients after coronary angiography. METHODS AND PATIENTS: We recruited 112 subjects with stable angina pectoris without a previous myocardial infarction: 17 consecutive patients with anatomically normal coronary arteries, 24 patients with non-significant coronary artery disease (CAD), 31 patients with significant left anterior descending coronary artery (LAD) disease and 40 patients with multivessel disease (MVD). Transoesophageal echocardiography (TEE) is useful for evaluation of the elastic properties of the descending aorta. The physical behaviour of vessels in response to an intraluminal force is described by the elastic modulus (E(p)) and Young's circumferential static elastic modulus (E(s)). Coronary flow velocities can be measured in the LAD under baseline conditions and during dipyridamole stress. The CFR was calculated as the ratio of the average peak diastolic flow velocity during hyperaemia to that at rest. RESULTS: The indices of aortic distensibility, CFR and mean CFR, were different in patients with LAD disease and in those with normal coronary angiograms. There were no further changes in these parameters in cases with MVD. In patients with non-significant CAD, the CFR, mean CFR and stiffness moduli lie between those for negative cases and those for patients with LAD disease/MVD. CONCLUSIONS: When there was significant stenosis of the LAD, the CFR was significantly decreased, while indices of aortic distensibility were increased as compared with the negative controls. Interestingly, not only the CFR, but also E(p) and E(s) displayed no further changes in cases with MVD as compared with LAD disease.     

Pulmonary venous flow dynamics before and after balloon mitral valvuloplasty as determined by transesophageal Doppler echocardiography.

The pattern of left atrial filling was studied in 14 patients with severe mitral stenosis in sinus rhythm before and immediately after successful balloon mitral valvuloplasty by transesophageal pulsed Doppler echocardiography of the left superior pulmonary vein. Mean mitral valve orifice area increased from 0.8 +/- 0.1 to 2.2 +/- 0.3 cm2 (p less than 0.0001), and left atrial mean pressure decreased from 30 +/- 5 to 12 +/- 4 mm Hg (p less than 0.0001) after the procedure. After balloon mitral valvuloplasty, significant increases in peak systolic pulmonary velocity (35 +/- 16 to 44 +/- 10 cm/s; p less than 0.01), systolic flow velocity time integral (3.3 +/- 1.5 to 5.9 +/- 2.0 cm; p less than 0.001) and the ratio of systolic/diastolic pulmonary venous flow velocity time integrals (0.8 +/- 0.4 to 1.4 +/- 0.5; p less than 0.001) were observed. An acute increase in mitral valve orifice area caused no significant changes in peak diastolic forward flow velocity (40 +/- 7 to 41 +/- 9 cm/s; p = not significant [NS]), diastolic forward flow velocity time integral (4.3 +/- 1.7 to 4.6 +/- 1.8 cm; p = NS) and atrial flow reversal velocity (30 +/- 3 to 35 +/- 3 cm/s; p = NS) compared with at baseline. The results suggest that in patients with severe mitral stenosis and sinus rhythm, left atrial filling is biphasic with a diastolic preponderance, and successful mitral valvuloplasty is associated with an immediate increase in pulmonary venous systolic forward flow.     

Coronary flow characteristics in hypertrophic cardiomyopathy--a study with Doppler catheter]

We compared the pattern and reserve of coronary flow in 8 cases of hypertrophic non-obstructive cardiomyopathy (H) with those in 20 cases of chest pain not accompanied by organic heart disease (N). A catheter-tip Doppler velocimeter was positioned in the proximal portion of the left anterior descending (LAD), circumflex (LCX) and right coronary (RCA) arteries. Coronary flow velocity (Vs: systolic peak, Vd: diastolic peak, Vm: mean) was recorded and the area under the velocity curve was divided into systole (* s) and diastole (* d). The time interval between the dicrotic notch in aortic pressure and the peak of diastolic flow velocity was measured (Tpv). Vm was measured before and after intracoronary injection of 6 ml of contrast media, and peak to resting velocity ratio (PRVR) was calculated as an index of coronary flow reserve. Result: In LAD, N showed diastolic predominant coronary flow pattern without backward flow. In H, diastolic predominance was more prominent with systolic backward flow, resulting in decrease in * s/* d(H: 0.07 +/- 0.04, N: 0.25 +/- 0.02, p less than 0.01). In H, Vd (H: 20.1 +/- 2.8, N: 9.2 +/- 1.4 cm/sec, p less than 0.05) and Vm(H: 9.5 +/- 1.3, N: 4.9 +/- 0.7 cm/sec, p less than 0.05) were higher, while PRVR was lower (H: 1.7 +/- 0.1, N: 2.6 +/- 0.1, p less than 0.05). In both N and H, the flow pattern of LCX was diastolic predominant with two peaks (one in systole and the other in diastole).(ABSTRACT TRUNCATED AT 250 WORDS)