Hyperinsulinemia during oral glucose tolerance test is associated with increased neointimal tissue proliferation after coronary stent implantation in nondiabetic patients: a serial intravascular ultrasound study

OBJECTIVES

The purpose of this study was to determine whether hyperinsulinemia during the oral glucose tolerance test is associated with increased neointimal tissue proliferation after coronary stent implantation in nondiabetic patients.

BACKGROUND

Although hyperinsulinemia induces increased vascular smooth muscle cell proliferation in experimental models, it has not been determined whether hyperinsulinemia is associated with increased neointimal tissue proliferation after coronary stent implantation.

METHODS

Serial (postintervention and six-month follow-up) intravascular ultrasound (IVUS) was used to study 67 lesions treated with Palmaz-Schatz stents in 55 nondiabetic patients. Cross-sectional images within stents were taken at every 1 mm, using an automatic pullback, and a neointimal index was calculated as the ratio between the averaged neointimal area and averaged stent area. All patients underwent a 75-g oral glucose tolerance test. Plasma glucose (PG) and immunoreactive insulin (IRI) levels were measured at baseline and 1 and 2 h after the glucose load. The sum of PGs (sigmaPG) and the sum of IRIs (sigmaIRI) were calculated. Body mass index (BMI), lipid levels, and glycosylated hemoglobin levels were measured.

RESULTS

There were 27 patients with normal glucose tolerance, and 28 patients with impaired glucose tolerance (IGT). The neointimal index in patients with IGT was greater than that in patients with normal glucose tolerance (42.9 +/- 14% vs. 24.9 +/- 8.3%, respectively, p < 0.0001). Linear regression analysis showed that the neointimal index at follow-up correlated well with sigmaPG (p < 0.0001), fasting IRI (p < 0.0001), sigmaIRI (p < 0.0001), triglyceride level (p = 0.018), and BMI (p < 0.0001). Multiple regression analysis revealed that sigmaIRI (p = 0.0002) and sigmaPG (p = 0.0034) were the best predictors of the greater neointimal index at follow-up.

CONCLUSIONS

Serial IVUS assessment shows that hyperinsulinemia during an oral glucose tolerance test is associated with increased neointimal tissue proliferation after coronary stent implantation in nondiabetic patients.

Relation of phasic coronary flow velocity characteristics with TIMI perfusion grade and myocardial recovery after primary percutaneous transluminal coronary angioplasty and rescue stenting

BACKGROUND

A residual stenosis and/or microvascular damage have been proposed as mechanisms of TIMI 2 flow for acute myocardial infarction. Coronary flow dynamics were assessed in patients with TIMI 2 flow to predict whether additional intervention would improve TIMI grade.

METHODS AND RESULTS

In 35 patients who had a successfully recanalized anterior acute myocardial infarction using angioplasty or rescue stenting, coronary flow patterns were compared with corresponding TIMI grade and regional left ventricular wall motion (LVWM) 1 month after the intervention. After angioplasty, the time-averaged peak velocity (APV) was lower in patients with TIMI 2 flow (n=22) than in those with TIMI 3 flow (n=13; 7.9+/-3.9 versus 20.6+/-5.1 cm/s; P<0.001). Two different flow patterns were recorded in patients with TIMI 2 flow (versus TIMI 3, P<0.001); patients with type 1 TIMI 2 flow (n=15) had a reduced diastolic APV (8.3+/-4.8 versus 24.2+/-7.4 cm/s), prolonged diastolic deceleration time (1176+/-455 versus 728+/-205 ms), and a small diastolic/systolic APV ratio (1.3+/-0.6 versus 2.1+/-0.7); patients with type 2 TIMI 2 flow (n=7) had systolic flow reversal (systolic APV, -7.9+/-4.6 versus 11. 7+/-4.5 cm/s), a rapid diastolic deceleration time (221+/-84 versus 728+/-205 ms), and a negative diastolic/systolic APV ratio (-2.1+/-1. 4 versus 2.1+/-0.7). A significantly lower mean chord LVWM (-3.0+/-0. 2 versus -1.9+/-0.8; P<0.001) and a greater number of chords <-2SD (50+/-2 versus 28+/-18; P<0.001) were present in patients with type 2 versus type 1 TIMI 2 flow. Stenting increased TIMI 2 flow to TIMI 3 flow more in patients with type 1 than type 2 flow (67% versus 0%; P=0.003). Patients with TIMI 2 flow after stenting continued to demonstrate a type 2 pattern, and they had poor LVWM recovery.

CONCLUSIONS

The differentiation between 2 types of TIMI 2 flow can predict the improvement of TIMI grade and LVWM recovery after additional stenting.

Compensatory enlargement of the coronary artery in acute myocardial infarction

Compensatory enlargement occurred in 71% of lesions in patients with acute myocardial infarction and was more common in these patients than in patients with stable effort angina pectoris. These results suggest that compensatory enlargement may be associated with plaque rupture and subsequent acute myocardial infarction.

Prediction of progression or regression of type A aortic intramural hematoma by computed tomography

BACKGROUND

It has been reported that early surgery should be required for patients with type A aortic intramural hematoma (IMH) because it tends to develop classic aortic dissection or rupture. However, the anatomic features of type A IMH that develops dissection or rupture are unknown. The purpose of this study was to investigate the predictors of progression or regression of type A IMH by computed tomography (CT).

METHODS AND RESULTS

Twenty-two consecutive patients with type A IMH were studied by serial CT images. Aortic diameter and aortic wall thickness of the ascending aorta were estimated in CT images at 3 levels on admission and at follow-up (mean 37 days). We defined patients who showed increased maximum aortic wall thickness in the follow-up CT (n=9) or died of rupture (n=1) as the progression group (n=10). The other 12 patients, who all showed decreased maximum wall thickness, were categorized as the regression group. In the progression group, the maximum aortic diameter in the initial CT was significantly greater than that in the regression group (55+/-6 vs 47+/-3 mm, P=0.001). A Cox regression analysis revealed that the maximum aortic diameter was the strongest predictor for progression of type A IMH. We considered the optimal cutoff value to be 50 mm for the maximum aortic diameter to predict progression (positive predictive value 83%, negative predictive value 100%).

CONCLUSIONS

Maximum aortic diameter estimated by the initial CT images is predictive for progression of type A IMH.

Can coronary blood flow velocity pattern after primary percutaneous transluminal coronary angioplasty [correction of angiography] predict recovery of regional left ventricular function in patients with acute myocardial infarction?

BACKGROUND

In the era of primary percutaneous transluminal coronary angioplasty (PTCA), it is important to judge whether myocardium within acute ischemic injury is viable. This study sought to investigate parameters derived from the coronary blood flow velocity spectrum immediately after primary PTCA in patients with acute myocardial infarction and to elucidate the clinical value of coronary blood flow measurement in predicting myocardial viability.

METHODS AND RESULTS

Using a Doppler guidewire, we measured coronary blood flow velocity after successful completion of primary PTCA in 23 consecutive patients with acute anterior myocardial infarction. Regional wall motion was analyzed to estimate anterior wall motion score index (A-WMSI) by echocardiography before PTCA and 1 month after the onset of symptoms. Average systolic peak velocity (ASV) and deceleration time of diastolic flow velocity (DDT) significantly correlated to 1-month A-WMSI (r=-0.54, P=0.007 and r=-0.62, P=0.002, respectively), and optimal cutoff values to predict viable myocardium (defined as 1-month A-WMSI </=2.0) were 6.5 cm/s for ASV and 600 ms for DDT (sensitivity=0.79, specificity=0.89 and sensitivity=0.86, specificity=0.89, respectively). ASV and DDT also correlated weakly to the change in A-WMSI (r=0.46, P=0.03 and r=0.49, P=0.02, respectively).

CONCLUSIONS

Low ASV and rapid DDT of coronary blood flow spectrum immediately after primary PTCA reflects a greater degree of microvascular damage in the risk area. Analysis of coronary blood flow spectrum immediately after primary PTCA by use of a Doppler guidewire is useful in predicting recovery of regional left ventricular function.

Noninvasive evaluation of pulmonary capillary wedge pressure in patients with acute myocardial infarction by deceleration time of pulmonary venous flow velocity in diastole

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.

Noninvasive assessment of hemodynamic subsets in patients with acute myocardial infarction using digital color Doppler velocity profile integration and pulmonary venous flow analysis

Four major hemodynamic subsets from cardiac index (CI) and mean pulmonary artery (PA) wedge pressure with a PA catheter usually reflect clinical status and prognosis of patients with acute myocardial infarction (AMI). Recently, a new color Doppler technique has been developed for automated cardiac output measurements (ACOM). Color Doppler echocardiography also provides noninvasive estimation of PA wedge pressure from pulmonary venous (PV) flow analysis. This study evaluates the value of ACOM and PV flow analysis by color Doppler echocardiography for the assessment of hemodynamic subsets in patients with AMI. We performed ACOM and PV flow analysis by color Doppler echocardiography in 55 patients with AMI who underwent hemodynamic assessment with a PA catheter. From both noninvasive and invasive methods, we classified hemodynamic subsets as follows: subset I: normal hemodynamics (CI >2.2 L/min/m2, PA wedge pressure < or =18 mm Hg); subset II: pulmonary congestion (CI >2.2 L/min/m2, PA wedge pressure >18 mm Hg); subset III: peripheral hypoperfusion (CI < or =2.2 L/min/m2, PA wedge pressure < or =18 mm Hg); and subset IV: pulmonary congestion and peripheral hypoperfusion (CI < or =2.2 L/min/m2, PA wedge pressure >18 mm Hg). Doppler assessment of hemodynamic subsets was possible in 50 of 55 patients (91%). CI from ACOM correlated well with that from the thermodilution method (r = 0.94) with close agreement. There was a good correlation between the systolic fraction (systolic velocity-time integral expressed as a fraction of the sum of systolic and diastolic velocity-time integrals) of PV flow and PA wedge pressure measured from cardiac catheterization (r = -0.83). When we determined the value of 45% in the systolic fraction as the cut-off point in predicting >18 mm Hg in PA wedge pressure, there was 90% (45 of 50 patients) agreement between noninvasive and invasive hemodynamic subsets. Thus, ACOM and PV flow analysis by color Doppler echocardiography is useful in the noninvasive assessment of hemodynamic subsets in patients with AMI.

[Effects of imaging parameters on automated cardiac flow measurement using color Doppler echocardiography]

The color Doppler echocardiographic technique has been developed for automated cardiac flow measurement (ACM). This study evaluated the effect of imaging parameters on stroke volume measurement. Cardiac output derived from the ACM method was compared with that obtained from pulsed wave Doppler in 36 patients (26 men and 10 women, mean age 54 +/- 8 years) in whom clear two-dimensional and color Doppler images of the left ventricular outflow tract were obtained. The effects of frame rate, color gain and moving target indicator (MTI) filter on cardiac output were evaluated in 13 patients (8 men and 5 women, mean age 49 +/- 6 years). Using ACM at a frame rate of 30 Hz, optimal color gain setting and high-frequency MTI filter (cutoff frequency: 915 Hz), there was an excellent correlation in cardiac output between the ACM and pulsed wave Doppler methods (stroke volume: r = 0.91, SEE = 0.32 l/min). Using ACM at a frame rate of 30, 22 and 15 Hz, the differences in stroke volume were 4.4%, 5.2% and 8.6%, respectively. When color gain was reduced, left ventricular stroke volume reduction was 12.1% (-2 dB), 18.9% (-4 dB). In contrast, there was no significant change in stroke volume measurement when color gain was increased. There was a significant decrease in stroke volume using the low-frequency MTI filter [cutoff frequency: 467 Hz (-35.6%)] and medium-frequency MTI filter [cutoff frequency: 703 Hz (-13.4%)]. Color Doppler imaging parameters are extremely important for automated assessment of cardiac output.

[Evaluation of mitral valve lesions in patients with infective endocarditis by three-dimensional echocardiography]

Recognition of the involved lesions is extremely important in mitral valve repair for infective endocarditis. Transesophageal echocardiography (TEE) is more sensitive for the detection of lesions than transthoracic echocardiography, but localization of the lesions is sometimes difficult by TEE. Three-dimensional (3D) TEE provides images of the mitral valve similar to the view from the left atrium. This study evaluated the value of 3D echocardiography for the diagnosis of involved lesions in 12 patients who underwent surgery for mitral regurgitation due to infective endocarditis. The location of the lesion in the mitral valve was classified as the medial, central and lateral portions of the anterior leaflet, and the medial, middle and lateral scallops of the posterior leaflet, respectively. In all patients, the involved sites were confirmed at operation. The sensitivities of 3D TEE for detecting the lesions at the medial, central and lateral portions of the anterior leaflet, and the medial, middle and lateral scallops of the posterior leaflet were 100%, 78% and 67%, and 100%, 100% and 100%, respectively. The specificities were 90%, 100% and 78%, and 100%, 100% and 100%, respectively. The lesions diagnosed by 3D TEE coincided with lesions confirmed at operation in 23 (92%) of 25 lesions. 3D TEE is useful for the assessment of the involved lesion of the mitral valve in patients with infective endocarditis.

Restricted coronary flow reserve in patients with mitral regurgitation improves after mitral reconstructive surgery

OBJECTIVES

The purpose of this study was to assess coronary flow characteristics in patients with chronic mitral regurgitation (MR).

BACKGROUND

Coronary flow reserve (CFR) has been reported to be restricted in cases with left ventricular (LV) volume overload caused by aortic regurgitation and increased LV preload.

METHODS

The study populations consisted of 31 patients with nonrheumatic chronic MR. Eleven with chest pain and normal coronary arteries served as control subjects. Phasic coronary flow velocities were obtained in the proximal segment of the angiographically normal left anterior descending coronary artery at rest and during hyperemia (0.14 mg/kg/min adenosine infusion intravenously) using a 0.014-in. (0.036 cm), 15-MHz Doppler guide wire. Coronary flow reserve was obtained from the ratio of hyperemic/baseline time-averaged peak velocity (APV). Thirteen cases who underwent mitral valve reconstructive surgery were also studied 1 month after surgery.

RESULTS

Compared with control subjects, CFR was significantly reduced in cases with MR (2.1+/-0.5 vs. 33+/-0.6, respectively, p < 0.01) because baseline APV was significantly greater (28+/-8 vs. 19+/-6 cm/s, respectively, p < 0.01), although maximal hyperemic APV was not significantly different (56+/-14 vs. 61+/-16 cm/s, respectively, p = NS). Significant correlations were obtained between CFR and LV end-diastolic pressure (LVEDP) (r = 0.70, p < 0.01), LV mass index (r = 0.42, p < 0.01), LV end-diastolic volume (r = 038, p = 0.04) and MR volume (r = 0.39, p = 0.03), and stepwise regression analysis showed LVEDP was the most important determinant of CFR in MR (r2 = 0.49, p < 0.0001). This restricted CFR improved significantly after mitral valve reconstructive surgery (2.1+/-0.5 vs. 3.1+/-0.6, respectively, p < 0.01) because of reduction of baseline APV (28+/-8 vs. 21+/-8 cm/s, respectively, p < 0.01).

CONCLUSIONS

Coronary flow reserve is limited in cases with MR because of elevation of baseline resting flow velocity. This reduction of CFR correlates well with increase in LV preload, mass and volume overload, especially with increase in LV preload, and this restricted CFR improves after mitral valve surgery.

Noninvasive assessment of coronary flow velocity and coronary flow velocity reserve in the left anterior descending coronary artery by Doppler echocardiography: comparison with invasive technique

OBJECTIVES

The purpose of this study was to evaluate whether transthoracic Doppler echocardiography (TTDE) can reliably measure coronary flow velocity (CFV) and coronary flow velocity reserve (CFVR) in the left anterior descending coronary artery (LAD) in the clinical setting.

BACKGROUND

Coronary flow velocity measurement has provided useful clinical and physiologic information. Advancement in TTDE provides noninvasive measurement of CFV and CFVR in the distal LAD.

METHODS

In 23 patients, CFV in the distal LAD was measured by TTDE (5 or 3.5 MHz) under the guidance of color Doppler flow mapping at the time of Doppler guide wire (DGW) examination. Coronary flow velocity in the distal LAD were measured at baseline and hyperemic conditions (intravenous administration of adenosine 0.14 mg/kg/min) by both TTDE and DGW techniques. Coronary flow velocity reserve was defined as the ratio of peak hyperemic to basal averaged peak velocity in the distal LAD.

RESULTS

Clear envelopes of basal and hyperemic CFV in the distal LAD were obtained in 18 (78%) of 23 study patients by TTDE. There were excellent correlations between TTDE and DGW methods for the measurements of CFV (averaged peak velocity: r=0.97, y=0.94x + 0.40; averaged diastolic peak velocity: r=0.97, y=0.94x + 0.69; systolic peak velocities: r=0.97, y=0.91x + 0.87; diastolic peak velocity: r=0.98, y=0.95x + 1.10). Coronary flow velocity reserve from TTDE correlated highly with those from DGW examinations (r=0.94, y=0.95x + 0.21).

CONCLUSIONS

Noninvasive measurement of CFV and CFVR in the distal LAD using TTDE accurately reflects invasive measurement of CFV and CFVR by DGW method.

[Assessment of coronary flow reserve in patients with hypertrophic cardiomyopathy using transthoracic color Doppler echocardiography]

Abnormal coronary flow pattern and coronary vasodilator reserve have been identified in patients with hypertrophic cardiomyopathy (HCM) using invasive techniques. The characteristics of coronary flow velocity and coronary flow reserve were evaluated by noninvasive-recording of coronary flow velocity in the distal portion of the left anterior descending coronary artery in 7 patients with HCM and 7 normal subjects using transthoracic color Doppler echocardiography. Coronary flow velocity was measured at rest and during intravenous infusion of adenosine triphosphate (0.15 mg/kg/min). Diastolic peak velocity, diastolic mean velocity, the time from the beginning of diastole to peak velocity (TVP) and velocity half time from peak velocity was measured in each group. Coronary flow reserve was obtained as the ratio of hyperemic mean velocity to resting mean velocity. TVP was significantly prolonged in the patients with HCM compared with the normal subjects (159 +/- 38 vs 103 +/- 54 msec, p < 0.05). Velocity half time was significantly shorter in the patients with HCM compared with the normal subjects (304 +/- 138 vs 451 +/- 109 msec, p < 0.05). Although diastolic mean velocity during hyperemia was not different between the 2 groups (62 +/- 8 vs 70 +/- 19 cm/sec), diastolic mean velocity at rest was significantly higher in the patients with HCM than in the normal subjects (39 +/- 6 vs 26 +/- 7 cm/sec, p < 0.01). Therefore, coronary flow reserve was significantly lower in the patients with HCM than in the normal subjects (1.6 +/- 0.4 vs 2.7 +/- 0.4, p < 0.001). There was a good correlation between diastolic mean velocity and the ratio of interventricular septal to posterior left ventricular wall thickness (y = 0.024x + 0.46, r = 0.75). Transthoracic assessment of coronary flow velocity using color Doppler echocardiography reveals that coronary flow reserve is reduced in patients with HCM because of increased baseline resting diastolic mean velocity.

Flow dynamics of angiographically no-flow patent internal mammary artery grafts

OBJECTIVES

This study sought to assess the flow dynamics of internal mammary artery grafts (IMAGs) in no-flow situations by use of a Doppler guide wire.

BACKGROUND

Functionally no-flow and anatomically patent IMAGs have been reported by angiography in patients with a patent recipient coronary artery.

METHODS

The study included 12 patients with an IMAG to the left anterior descending coronary artery (LAD) in whom no-flow patency of the graft was suspected angiographically. Thirteen patients with a normally functioning IMAG whose LAD was occluded in the proximal portion and was supplied only from the graft served as control patients. Phasic flow velocities were recorded in the distal portion of the graft and the recipient LAD using a 0.014-in., 15-MHz Doppler guide wire at rest and during hyperemia (0.14-mg/kg body weight per min intravenous adenosine infusion).

RESULTS

There were no significant differences in systolic (15+/-3 vs. 19+/-6 cm/s, p = NS), diastolic (35+/-11 vs. 37+/-7 cm/s, p = NS) and time-averaged peak velocities at rest (20+/-5 vs. 21+/-5 cm/s, p = NS), during hyperemia (51+/-12 vs. 54+/-8 cm/s, p = NS) and in coronary flow velocity reserve (2.8+/-0.9 vs. 2.7+/-0.3, NS) in the native LAD in patients with a no-flow patent graft versus control patients. Within the graft, to and fro signals with systolic reversal and diastolic anterograde flow were seen in the no-flow patent grafts, although anterograde flow signals were recorded in systole and diastole in control patients. Systolic (-28+/-19 vs. 22+/-9 cm/s, p < 0.01), diastolic (18+/-17 vs. 44+/-14 cm/s, p < 0.01) and time-averaged (-2+/-6 vs. 26+/-9 cm/s, p < 0.01) peak velocities at rest were significantly smaller in the no-flow patent grafts than in control grafts. During hyperemia, anterograde flow became predominant, with a reduction in retrograde systolic flow signal and an increase in diastolic flow velocity and time-averaged peak velocity in the no-flow patent grafts, and no-flow situations disappeared temporarily.

CONCLUSIONS

Functionally no-flow situations of IMAGs manifesting to and fro signals with systolic flow reversal and diastolic antegrade low flow velocity are temporary conditions in certain hemodynamic circumstances, and these grafts function as conduits during hyperemic states.

[Automated cardiac output measurement by color Doppler echocardiography]

Recently, automated cardiac flow measurement (ACM) has been developed for measuring the volume flow rate of blood flow through the left ventricular outflow tract. Measurements of left ventricular cardiac output by the ACM method were compared with those by the thermal dilution method with a Swan-Ganz catheter in 27 patients (16 men and 11 women; aged 44 +/- 3 years) in whom clear two-dimensional and color Doppler images of the left ventricular outflow tract were obtained. The total time required for left ventricular stroke volume calculation by both ACM and pulsed Doppler methods was measured in 10 patients (six men and four women; aged 41 +/- 2 years). There was an excellent correlation in the measurements of cardiac output between the ACM and thermal dilution methods (y = 0.77x + 0.77, r = 0.84, SEE = 0.4 l/min). The total time required for left ventricular stroke volume calculation by the ACM method was significantly shorter than that by the pulsed Doppler method (92 +/- 10 vs 177 +/- 30 sec, p < 0.01). The ACM method is simple, quick, and accurate for the automated assessment of cardiac output.

[Measurement of plaque volume using three-dimensional intravascular ultrasound: in vitro study]

The usefulness of three-dimensional echocardiography using intravascular ultrasound (3D-IVUS) for the measurement of plaque volume was evaluated by comparing plaque volume derived from 3D-IVUS with that directly measured in 10 autopsied iliac or femoral plaque models (5-15 mm long). Using IVUS (3.5 F, 30 MHz), sequential cross-sectional images for three-dimensional datasets were acquired with a motorized catheter pullback device connected to the three-dimensional reconstruction system. Three-dimensional reconstruction was performed from the sum of the two-dimensional cross-sectional views. Plaque volumes were calculated using a summation of disks algorithm based on the reconstructed multiple short-axis cross-sections from the three-dimensional data. Three-dimensional IVUS demonstrated a good correlation with direct measurement of plaque volume (y = 0.71x + 0.001, r = 0.80, SEE = 0.003 ml), so is useful for the measurement of plaque volumes in the experimental models.

Retinopathy identifies marked restriction of coronary flow reserve in patients with diabetes mellitus

OBJECTIVES

This study sought to assess the differences in coronary flow reserve in patients with and without diabetic retinopathy.

BACKGROUND

Microvascular abnormalities throughout the body and impairment of coronary flow reserve have been described in patients with diabetes mellitus. However, the relation between diabetic retinopathy and coronary microvascular disease has not been investigated.

METHODS

The study included 29 patients with diabetes mellitus (18 with and 11 without diabetic retinopathy) and 15 control patients with chest pain and normal coronary arteries. Diabetic retinopathy was nonproliferative in all 18 patients with this disorder (8 had background, 10 preproliferative retinopathy). Five minutes after injection of 3 mg of isosorbide dinitrate, phasic flow velocities were recorded in the proximal segment of the angiographically normal left anterior descending coronary artery at rest and during hyperemia (0.14 mg/kg body weight per min of adenosine infused intravenously) using a 0.014-in. 15-MHz Doppler guide wire. Coronary blood flow was calculated, and coronary flow reserve was obtained from the hyperemic/baseline flow ratio.

RESULTS

Coronary blood flow was significantly lower during hyperemia ([mean +/- SD] 107 +/- 23 and 116 +/- 18 vs. 136 +/- 17 ml/min, respectively) and higher at baseline (58 +/- 16 and 45 +/- 12 vs. 37 +/- 10 ml/min, respectively) in diabetic patients with and without retinopathy than in control subjects (p < 0.05 for both diabetic groups). As a result, coronary flow reserve in both groups of diabetic patients was significantly lower than in control patients (1.9 +/- 0.4 and 2.8 +/- 0.3 vs. 3.3 +/- 0.4, respectively, p < 0.01 for both diabetic groups), and its reduction was greater in patients with than without retinopathy (p < 0.01). Furthermore, in patients with diabetic retinopathy, maximal hyperemic coronary flow (102 +/- 11 vs. 114 +/- 16 ml/min, p < 0.05) and flow reserve (1.6 +/- 0.2 vs. 2.3 +/- 0.2, p < 0.01) were significantly lower in those with preproliferative than background retinopathy.

CONCLUSIONS

Coronary flow reserve is significantly restricted in patients with diabetes mellitus, and its reduction is more marked in those with diabetic retinopathy, especially in advanced retinopathy. Thus, diabetic retinopathy should identify marked restriction of coronary flow reserve in patients with diabetes mellitus.

Identification of genetic mutations in Japanese patients with fructose-1,6-bisphosphatase deficiency

Fructose-1,6-bisphosphatase (FBPase) deficiency is an autosomal recessive inherited disorder and may cause sudden unexpected infant death. We reported the first case of molecular diagnosis of FBPase deficiency, using cultured monocytes as a source for FBPase mRNA. In the present study, we confirmed the presence of the same genetic mutation in this patient by amplifying genomic DNA. Molecular analysis was also performed to diagnose another 12 Japanese patients with FBPase deficiency. Four mutations responsible for FBPase deficiency were identified in 10 patients from 8 unrelated families among a total of 13 patients from 11 unrelated families; no mutation was found in the remaining 3 patients from 3 unrelated families. The identified mutations included the mutation reported earlier, with an insertion of one G residue at base 961 in exon 7 (960/961insG) (10 alleles, including 2 alleles in the Japanese family from our previous report [46% of the 22 mutant alleles]), and three novel mutations--a G-->A transition at base 490 in exon 4 (G164S) (3 alleles [14%]), a C-->A transversion at base 530 in exon 4 (A177D) (1 allele [4%]), and a G-->T transversion at base 88 in exon 1 (E30X) (2 alleles [9%]). FBPase proteins with G164S or A177D mutations were enzymatically inactive when purified from E. coli. Another new mutation, a T-->C transition at base 974 in exon 7 (V325A), was found in the same allele with the G164S mutation in one family (one allele) but was not responsible for FBPase deficiency. Our results indicate that the insertion of one G residue at base 961 was associated with a preferential disease-causing alternation in 13 Japanese patients. Our results also indicate accurate carrier detection in eight families (73%) of 11 Japanese patients with FBPase deficiency, in whom mutations in both alleles were identified.

Comparison of coronary flow reserve between focal and diffuse vasoconstriction induced by ergonovine in patients with vasospastic angina

Decreased coronary flow reserve has been reported in patients with ergonovine-induced coronary vasoconstriction by the thermodilution method. To assess the difference of coronary flow reserve between patients with focal and diffuse vasospasm, after the vasospasm is discontinued by injection 3 mg of isosorbide dinitrate, phasic flow velocities of the diseased coronary artery were recorded at rest and during hyperemia (140 microg/kg/min of adenosine infusion intravenously) using a 0.014-inch, 15-MHz Doppler guidewire in 26 patients with ergonovine-induced coronary vasospasm (0.2-mg ergonovine injection intravenously), including 12 patients with focal (>90% stenosis), 14 patients with diffuse vasospasm (>50%), and 11 controls with normal coronary arteries without vasospasm. Although time-averaged peak velocity in cases with diffuse and focal vasospasm was not significantly different compared with that in controls at baseline (22 +/- 7, 18 +/- 5 vs 20 +/- 7 cm/s, respectively, NS), it was significantly lower in patients with diffuse vasospasm than in cases with focal vasospasm and in controls during hyperemia (43 +/- 13 vs 64 +/- 18, 61 +/- 19 cm/s, respectively, p <0.01). As a result, coronary flow reserve obtained from the ratio of hyperemic/baseline time-averaged peak velocity was significantly lower in patients with diffuse vasospasm than that in controls (1.9 +/- 0.4 vs 3.1 +/- 0.4, p <0.01), although it was not significantly different between the subjects with focal vasospasm and controls (3.5 +/- 0.7 vs 3.1 +/- 0.4, NS). Thus, coronary flow reserve is maintained normally in patients with focal vasospasm and limited in those with diffuse vasospasm. Microvascular impairment could exist further in cases with diffuse vasospasm, although similar endothelial dysfunction of the epicardial coronary artery is observed in focal and diffuse vasospasm.

[Transthoracic digital color Doppler assessment of the left anterior descending coronary artery and intramyocardial blood flow]

Noninvasive assessment of the distal left anterior descending coronary artery and intramyocardial blood flow were attempted in 50 consecutive patients (28 males and 22 females, mean age [+/-SD] 58 +/- 12 years) using a 7.5 MHz transducer (Doppler frequency: 5 MHz) and a SSA-380A ultrasound digital system with special optimal settings for the color Doppler examination. Modified apical acoustic windows were used to visualize the blood flow in the distal left anterior descending coronary artery and the intramyocardial artery. By selecting a sample volume (2 mm wide) on the color trace of these blood flows, Doppler spectral tracing of the distal left anterior descending coronary artery and intramyocardial blood flows could be recorded using pulsed-wave Doppler system. Blood flow in the distal left anterior descending coronary artery was detected in 43 (86%, Vmax = 22 +/- 8.7 cm/sec, Vmean = 16 +/- 5.1 cm/sec) of 50 patients, and intramyocardial blood flow in 40 (80%, Vmax = 26 +/- 11.0 cm/sec, Vmean = 19 +/- 8.5 cm/sec) of 50 patients. Distal left anterior descending coronary artery and the intramyocardial blood flows can be imaged by transthoracic digital color Doppler echocardiography in the clinical setting.

Chondrocyte migration to fibronectin, type I collagen, and type II collagen

It is well known that cellular interactions, such as cell adhesion, migration, invasion, between cells and the extracellular matrix are mediated by the integrin family of cell surface receptors. Chondrocytes are surrounded by an abundant extracellular matrix, but there is less information on the cellular receptors which interact with this matrix. In our studies, fibronectin, type I collagen, and type II collagen promoted haptotactic and chemotactic migration of chondrocytes, as determined using a modified Boyden chamber system. Treatment of chondrocytes with tyrosine kinase inhibitor, herbimycin or genistein, resulted in a dose dependent inhibition of migration toward these matrix proteins, whereas adhesion of chondrocytes was not influenced. This indicated the existence of functional relationships between protein tyrosine phosphorylation and chondrocyte migration following the adhesion of chondrocytes to matrix proteins. Further study showed that the peptide GRGDSP inhibited chondrocyte migration to fibronectin but not to collagens. On the other hand, chondrocytes migrated toward the tetra-RGD containing peptide, but not the peptide GRGDSP, in a dose dependent fashion. These observations suggest that cross-linking or clustering of integrins is essential to induce transmembrane signaling related to tyrosine phosphorylation for chondrocyte migration toward fibronectin.

Identification of a genetic mutation in a family with fructose-1,6- bisphosphatase deficiency

Fructose-1,6-bisphosphatase deficiency is an inheritable disorder of gluconeogenesis. Sequence analysis of the cDNA of the fructose-1,6-bisphosphatase mRNA isolated from monocytes from a girl with this disease and her consanguineous parents revealed that the patient and her parents were a homozygote and heterozygotes for an insertion of one G residue at G957GGGG961, respectively. This mutation resulted in translation of a truncated enzyme protein, and the mutant protein showed no fructose-1,6- bisphosphatase activity in an overexpression experiment in Escherichia coli. However, this mutation is located in a region of the amino acid sequence which is not well conserved among mammals. A mutagenized clone was prepared from the normal clone. The extents of substitutions and deletions of the amino acid sequence were predicted to be less in the mutagenized protein than in the mutant protein. This mutagenized clone also expressed no fructose-1,6-bisphosphatase activity, although both of two normal clones from control monocytes and a control liver sample expressed an apparently normal level of fructose-1,6-bisphosphatase activity. Thus, this mutation is concluded to be responsible for fructose-1,6-bisphosphatase deficiency in this patient.

A clinical and histologic comparison between free temporoparietal and scapular fascial flaps

It is universally accepted that the fascial flap is one of the best reconstructive strategies for contour and tendon-gliding function. In this study we compare the free temporoparietal fascial flap (n = 20) and the free scapular fascial flap (n = 6) mainly for these reconstructions and discuss their characteristics, including different clinical applications and histologic examination. Our histologic analysis reveals that the free temporoparietal fascial flap has a potential like a muscle flap; moreover, it is very thin. The free scapular fascial flap is very rich in adipose tissues to prevent adhesion between the flap and underlying tissues. Both flaps in our experience can bring satisfaction to the recipient site, but the donor site of the free temporoparietal fascial flap sometimes suffers from conspicuous widened scars in short-haired patients, and the scapular fascia has a tendency to be thicker in obese patients. Therefore, we recommend using the free temporoparietal fascial flap for women, who tend to have more fat and longer hair, and the free scapular fascial flap for men, who tend to be lean and shorten their side hair.