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Biomedical subjects

J M Hodgson

Publications and source records attributed to J M Hodgson.

At least 73 records · Page 4Linked to original sources
PubMed1990

Percutaneous intracoronary ultrasound imaging: initial applications in patients.

This study was designed to evaluate the feasibility and potential clinical utility of intracoronary ultrasound imaging in patients using a 5.5 F synthetic aperture array, over-a-wire ultrasound catheter. Thirty patients underwent percutaneous intracoronary (n = 22) or peripheral (n = 8) ultrasound imaging at the time of cardiac catheterization. Ultrasound images were compared to simultaneous digital angiograms. Correlation between ultrasonic and angiographic estimation of coronary diameters was good (r = 0.80). Morphological analysis of ultrasound images obtained in patients revealed a pattern consistent with mild-to-minimal atherosclerosis, as defined by prior in vitro studies. In 15 patients, imaging was performed during intracoronary infusion of vasoactive medications (papaverine 15 mg, nitroglycerine 100 mugm, and acetylcholine 2 x 10 -5 or 2 x 10 -6M). These medications were also infused during continuous intracoronary Doppler catheter monitoring of velocity and pressure, thus allowing calculation of volume flow and coronary resistance indices. Serial determination of ultrasound-derived epicardial vessel cross-sectional area demonstrated no change (-1 +/- 1%) after papaverine, an 8 +/- 2% increase after nitroglycerine, and a 9 +/- 3% decrease after acetylcholine. Calculated resistance fell 53 +/- 4% after acetylcholine and 60 +/- 3% after papaverine. Preliminary in vitro studies using a combination angioplasty balloon/ultrasound catheter demonstrated the ability to visualize vessel dilation in real time. We conclude that intravascular ultrasound imaging will be useful for dimensional and morphological characterization of vascular disease, for beat-to-beat monitoring of vasomotion, and potentially as a real-time adjunct to therapeutic interventions.

Adult↗
PubMed1989

Clinical percutaneous imaging of coronary anatomy using an over-the-wire ultrasound catheter system.

This manuscript describes initial applications of a unique new intravascular ultrasound imaging catheter. This 5.5F catheter uses an over-the-wire design and incorporates a phased array transducer at its tip. There are no moving parts. A 360 degree image is produced perpendicular to the catheter axis using a 20 MHz center frequency. A dedicated minicomputer is used for initial image processing, as well as enhancement and analysis. Initial studies using phantoms demonstrated excellent accuracy for linear dimensions (r = 0.99, range 3.0 to 7.6 mm, image = 1.0 phantom + 0.1). Serial imaging of the same arterial segment in vitro showed good reproducibility (coefficients of variance 2.5-5.2%). Likewise, intra- and inter-observer variability in image analysis was minimal (r = 0.92-0.99). Initial in vivo studies were performed in dogs. The catheter was easily passed over a wire into mesenteric, cerebral and coronary vessels without evidence of significant vessel trauma. Subsequently, 20 patients had percutaneous coronary imaging performed during cardiac catheterization. Cardiac motion was rarely a problem and acceptable images were obtained in all but two patients. Areas of calcification, mild stenoses, branching vessels and graft atherosclerosis could be identified. We conclude that intracoronary ultrasound imaging will be useful for assessing vascular pathology, for studying both rapid change in vessel size as well as chronic progression or regression of atherosclerosis, and for assisting with new therapeutic interventions.

Angioplasty, Balloon↗
PubMed1989

Oral habits in common between tension headache and non-headache populations.

Previous research has suggested a relationship between migraine pain and oral habits. The present study was designed as a replication of a prior study that found self-reported higher frequencies of certain oral habits in migraine as opposed to tension headache and non-headache groups. Three groups of subjects (common migraine, tension headache and non-headache) were given a single questionnaire in which five oral habits (i.e. teeth clenching, jaw jutting, cupping the chin in the hand, and resting the right and left side of the face on the hand) were rated on a 0 (not at all) to 10 (almost always) scale. Significant main effects were obtained for groups and oral habits in a 3 (groups) X5 (oral habits) ANOVA. Post hoc Tukey tests revealed the common migraine group reported significantly more frequent oral habits than did the tension headache group. The non-headache control group did not differ significantly from either headache group. Discussion focuses on the need for continued research in this area.

Adult↗
PubMed1989

Effects of regional alpha- and beta-blockade on resting and hyperemic coronary blood flow in conscious, unstressed humans.

Our purpose was to determine if there are basal adrenergic influences on the coronary circulation in humans. We studied 56 patients with denervated hearts after cardiac transplantation and 19 normally innervated patients with angiographically normal coronary arteries. Coronary blood flow velocity was measured during cardiac catheterization with a subselective 3F intracoronary Doppler catheter. Heart rate was controlled by atrial pacing. Epicardial coronary artery diameter was measured by automated analysis of digital coronary angiograms. Coronary flow reserve was assessed by intracoronary papaverine hydrochloride (12 mg) injections. Regional sympathetic blockade was produced by intracoronary injections of phentolamine (3 mg, alpha) and propranolol (2 mg, beta) or metoprolol (3 mg, beta 1). After alpha-blockade, mean arterial pressure fell significantly (p less than 0.05) in both the denervated transplant (-5.8 +/- 1.5%) (mean +/- SEM) and normally innervated patients (-12.6 +/- 3.2%). Reductions in coronary flow velocity also were observed in these groups (-8.2 +/- 2.3% and -9.2 +/- 5.8%, respectively). Calculated coronary vascular resistance was unchanged. Similar changes were seen when patients were pretreated with beta-blockade before alpha-blockade. Nonspecific beta-blockade did not affect mean arterial pressure but decreased coronary velocity (innervated, -11.6 +/- 3.9%; denervated, -9.3 +/- 2.4%) and increased coronary vascular resistance (innervated, 15.4 +/- 6.7%; denervated, 10.2 +/- 3.7%). Coronary vascular resistance did not rise in either group after selective beta 1-blockade with metoprolol. Coronary flow reserve did not change in either patient group after either alpha- or beta-blockade. Changes in epicardial coronary artery diameter were small and generally not significant. These data suggest that alpha-receptor-mediated vascular tone is negligible in both denervated transplant patients and normally innervated patients. Additionally, the increase in vascular resistance after nonselective beta-blockade is the result of direct beta 2 vascular effects. Our data further suggest that there is little adrenergically mediated epicardial artery tone (either humoral or neural) at rest and that maximal vasodilator responses are not limited by adrenergically mediated vasomotor tone.

Adrenergic alpha-Antagonists↗
PubMed1989

Direct vasoconstriction and endothelium-dependent vasodilation. Mechanisms of acetylcholine effects on coronary flow and arterial diameter in patients with nonstenotic coronary arteries.

An endothelium-dependent vasodilator response to acetylcholine has been described recently in patients with coronary artery disease. Those studies determined responses only of large epicardial arteries. Our study was designed to determine the integrated effects of acetylcholine on epicardial diameter, coronary flow, and vascular resistance. Patients (n = 64) with nonstenotic epicardial coronaries underwent coronary angiography with simultaneous recording of coronary flow velocity using a 3F subselective Doppler catheter. Measurements of epicardial arterial cross-sectional area (ECA), velocity, estimated flow (velocity times area), and vascular resistance were made before and after bolus administration of acetylcholine (100 micrograms i.c.). Similar measurements were made after papaverine (12-15 mg i.c.), a nonendothelium-dependent vasodilator. Acetylcholine resulted in a reduction of ECA of 19 +/- 3%, whereas papaverine increased ECA by 9 +/- 2%. Estimated flow increased 69 +/- 12% after acetylcholine and 147 +/- 12% after papaverine. Resistance fell after both agents (acetylcholine, -17 +/- 13%; papaverine, -61 +/- 2%). Transvascular resistance fell after acetylcholine in all but five patients. These patients had dramatic epicardial artery constriction (40 +/- 8% decrease in ECA). The effect of acetylcholine on both ECA and resistance was blocked by atropine (1 mg i.c.). Nitroglycerin (300 micrograms i.c.) resulted in epicardial dilatation (7.5 +/- 2.8%) in the same patients in whom acetylcholine caused constriction (-11.2 +/- 3.1%).(ABSTRACT TRUNCATED AT 250 WORDS)

Acetylcholine↗
PubMed1989

Ventricular sensory endings mediate reflex bradycardia during coronary arteriography in humans.

It has been suggested that the response to the intracoronary injection of radiographic contrast is reflex in origin and results from stimulation of ventricular sensory endings. Cardiac transplantation results in denervation of the ventricles, and thus, may interrupt the afferent limb of this reflex. In contrast, the recipient sinus node and atrial remnant remain innervated, leaving the efferent cardiac limb of this reflex intact. We hypothesized that if contrast-induced reflex bradycardia and hypotension occurred from stimulation of ventricular chemosensitive endings, then this response would be abolished after cardiac transplantation. To test this hypothesis, we determined the changes in recipient (innervated) and donor (denervated) sinus-node rates (SNR) and mean arterial pressure during selective right (RCA) and left coronary artery (LCA) injection during arteriography in cardiac transplant patients and in patients with intact cardiac innervation. An increase in the recipient SNR was observed in cardiac transplant patients during left and right coronary injections (LCA, 6.6 +/- 1.7 beats/min; RCA, 2.4 +/- 1.4 beats/min) compared with a decrease in the control subjects (LCA, -15.3 +/- 2.3 beats/min; RCA, -6.9 +/- 1.9 beats/min; p less than 0.05 vs. control). This occurred despite significant and comparable decreases in mean arterial pressure in cardiac transplant patients (LCA, -12.7 +/- 2.3 mm Hg; RCA, -11.4 +/- 2.2 mm Hg) and control subjects (LCA, -18.7 +/- 1.7 mm Hg; RCA, -10.7 +/- 1.6 mm Hg). The donor SNR slowed for LCA injection (-5.4 +/- 2.1 beats/min, p less than 0.05) and RCA injection (-3.0 +/- 1.7 beats/min), which, for the LCA, was less than the slowing of control subjects (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Afferent Pathways↗
PubMed1988

Subcellular Location of NADPH-Dependent Hydroxypyruvate Reductase Activity in Leaf Protoplasts of Pisum sativum L. and Its Role in Photorespiratory Metabolism.

Protoplasts purified from pea (Pisum sativum L.) leaves were lysed and fractionated to assess the subcellular distribution of NADPH-dependent hydroxypyruvate reductase (NADPH-HPR) activity. Rate-zonal centrifugation and sucrose-gradient experiments demonstrated that most (about 70%) of the NADPH-HPR activity was located in the supernatant or cytosol fraction. Detectable, but relatively minor activities were associated with the chloroplast fraction (up to 10% on a chlorophyll basis when compared to the lysate) and with peroxisomes. The minor NADPH-HPR activity in the peroxisomes could be fully accounted for by the secondary NADPH-dependent activity of NADH-dependent HPR. The subcellular distribution of NADPH-HPR followed closely that previously determined for NADPH-dependent glyoxylate reductase (NADPH-GR), an enzyme localized predominantly in the cytosol of pea leaf protoplasts (CV Givan et al. 1988 J Plant Physiol 132: 593-599). Low activities of both NADPH-HPR and NADPH-GR were also found in purified chloroplasts prepared by mechanical homogenization of Pisum and Spinacia leaves. In pea and spinach chloroplasts, rates of both NADPH-HPR and NADPH-GR were lower than the activity of the NADH-dependent GR. The results are discussed in relation to a possible role for NADPH-HPR in the oxidative carbon pathway of photorespiration. Both NADPH-HPR and the GRs could function as auxiliary reactions to photorespiration, utilizing hydroxypyruvate and/or glyoxylate ;leaked' or otherwise exported from peroxisomes. NADPH-HPR function might be especially significant under conditions of limiting NADH supply to peroxisomes, with extraperoxisomal reduced pyridine nucleotide acting as the reductant.

Journal Article↗
PubMed1987

Assessment of coronary flow reserve using digital angiography before and after successful percutaneous transluminal coronary angioplasty.

Important alterations of coronary blood flow and coronary flow reserve occur during percutaneous transluminal coronary angioplasty (PTCA). This study evaluated these alterations using digital subtraction angiography. Coronary flow reserve was determined before and after successful PTCA in 20 patients with 1-vessel coronary artery disease (CAD). Ten other patients with angiographically normal coronary arteries, normal exercise electrocardiographic responses and normal cardiac structure also were evaluated. Coronary flow reserve was calculated as the ratio of papavarine-induced hyperemic flow to basal flow. Flow reserve for the stenotic artery in patients who underwent PTCA was 1.6 +/- 0.2 (mean +/- standard error of the mean) (range 0.9 to 3.9, n = 20). After successful PTCA, flow reserve for this artery increased to 3.1 +/- 0.2 (range 1.7 to 5.2, n = 20) (p less than 0.0001 vs before PTCA). Flow reserve for adjacent nonstenotic, nondilated arteries was 2.6 +/- 0.2 (range 1.4 to 4.5, n = 13). Coronary flow reserve in the stenotic arteries before PTCA was far below normal. In addition, both successfully dilated arteries and nondilated, nonstenotic arteries in these patients with CAD had flow reserve values smaller than those in the patients with normal arteries (4.8 +/- 0.6, range 2.3 to 12.6, n =22) (p less than 0.01). These findings suggest that digital angiographic determinations of coronary flow reserve can reveal important alterations of individual artery vasodilatory capacity. The data suggest that although an epicardial coronary in a patient with CAD may appear angiographically normal, flow reserve remains impaired due to abnormalities as yet undefined.

Adult↗
PubMed1987

Superiority of intracoronary papaverine to radiographic contrast for measuring coronary flow reserve in patients with ischemic heart disease.

Measurement of coronary flow reserve has been suggested as an adjunct to anatomic assessment of coronary stenoses in patients with ischemic heart disease. We compared papaverine hydrochloride and radiographic contrast to determine which agent was superior for the determination of coronary flow reserve. Coronary flow reserve was determined during cardiac catheterization by means of digital coronary angiography and parametric imaging. Two groups of patients were studied. Among patients in group 1, coronary flow reserve was determined by means of both papaverine and contrast. In group 1 patients with normal coronary arteries, papaverine-induced flow reserve was greater than contrast-induced reserve in all but one vascular region (n = 9, 4.98 +/- 1.15 vs 3.56 +/- 0.89; p = 0.29). Group 1 patients with coronary disease also demonstrated significantly greater flow reserve with papaverine (n = 25, 2.57 +/- 0.20 vs 1.83 +/- 0.11, p less than 0.01). Group 2 included patients with single-vessel coronary artery stenoses. These patients were studied by means of either papaverine or contrast to determine coronary flow reserve for both the stenotic "ischemic" region and an adjacent nonstenotic, "nonischemic" region. Those patients in group 2 who were studied by means of contrast had a modest difference between flow reserve values in the nonischemic and those in the ischemic regions (n = 15, 1.78 +/- 0.10 vs 1.26 +/- 0.09; p less than .0001) with considerable overlap. Patients studied by means of papaverine had a much greater separation in flow reserve between nonischemic and ischemic regions (n = 22, 2.78 +/- 0.19 vs 1.46 +/- 0.14; p less than 0.0001).(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Flow Velocity↗
PubMed1987

Value of exercise radionuclide ventriculography and thallium-201 scintigraphy in evaluating successful coronary angioplasty: comparison with coronary flow reserve, translesional gradient and percent diameter stenosis.

Assessment of percutaneous transluminal coronary angioplasty (PTCA) by early radionuclide exercise test was evaluated for 11 arteries undergoing a successful procedure. Exercise thallium-201 (Tl-201) and radionuclide ventriculography (RNV) were performed within 3 days before and after PTCA and compared to % diameter stenosis, % translesional gradient and regional coronary flow reserve (CFR) determined by digital coronary angiography. Primary success of the procedure was gauged by reduction in % stenosis from 80 +/- 12% to 31 +/- 12% (residual stenosis less than 50% in all cases) and reduction in % gradient less than 25% in all cases). Before PTCA, Tl-201 and/or RNV were abnormal in all cases. After PTCA, radionuclide exercise tests improved but remained abnormal in 4 instances. No relationship was found between residual % gradient or stenosis and pathological Tl-201 or RNV following PTCA, but abnormal tests were observed among 4 out of the 5 vessels with the lowest CFR (less than 1.69). In one case CFR remained depressed despite good angiographic, hemodynamic and scintigraphic results, this patient had unstable angina before the procedure. Among patients with stable symptoms, CFR of arterial distributions with positive Tl-201 or RNV after PTCA was significantly lower than that with negative tests (1.58 +/- 0.05 as compared to 1.90 +/- 0.25, P less than 0.02). Early radionuclide stress tests results thus reflect the physiologic improvement of coronary circulation. They may reflect the persistence of coronary flow abnormalities despite the relief of the epicardial stenosis.

Angioplasty, Balloon↗
PubMed1986

Intermittent, ambulatory dobutamine infusions in patients with severe congestive heart failure.

Thirteen ambulatory patients with severe congestive heart failure were treated with weekly, outpatient 48-hour infusions of dobutamine. All 13 patients had at least a 25% increase in cardiac output during initial dobutamine titration, with a corresponding improvement in systemic vascular resistance. Improvement in functional class was achieved in only seven patients. Additionally, only three patients survived the 26-week study period. Although no change in ventricular ectopy was noted during the initial dobutamine infusions, six patients experienced sudden death; three other patients died of progressive heart failure and one died from pulmonary embolism. These data suggest that chronic intermittent ambulatory dobutamine infusions are only partly successful in improving symptoms and probably do not prolong survival in patients with severe congestive heart failure. Administration of this form of therapy on a clinical basis should be undertaken cautiously until safety and efficacy are demonstrated in prospective, controlled trials.

Aged↗
PubMed1986

Coronary flow reserve provided by sequential internal mammary artery grafts.

Although internal mammary artery bypass grafts have a high patency rate, the adequacy of blood flow through such conduits, particularly if used sequentially, has been questioned. To evaluate this issue, coronary flow reserve was studied in 20 patients after coronary bypass surgery. Nine patients had sequential internal mammary grafts to the diagonal and left anterior descending coronary arteries; five had a single internal mammary graft to the left anterior descending artery and six had sequential saphenous vein grafts. Fifteen additional single vein grafts were also placed in these patients. Coronary flow reserve was measured after contrast-induced hyperemia by a digital subtraction angiographic technique an average of 25 days after surgery. There was no difference in coronary flow reserve between the proximal and distal anastomotic regions in either the sequential internal mammary graft group (2.14 +/- 0.50 versus 2.29 +/- 0.68, n = 8, p = NS) or the sequential vein group (1.77 +/- 0.49 versus 2.08 +/- 0.78, n = 6, p = NS). In addition, the flow reserve provided to either vascular bed of the sequential internal mammary graft was not different from that provided by a single internal mammary graft (1.64 +/- 0.39, n = 5), a single vein graft (1.95 +/- 0.95, n = 15) or nonstenotic native coronary arteries (2.04 +/- 0.87, n = 34). No cases of intracoronary steal were observed. Although some patients had unequal flow reserves between the proximal and distal anastomotic zones, these occurred in the setting of residual coronary stenoses distal to the site of graft insertion or prior myocardial infarction in the grafted distribution.(ABSTRACT TRUNCATED AT 250 WORDS)

Cardiac Catheterization↗
PubMed1986

Comparative study of coronary flow reserve, coronary anatomy and results of radionuclide exercise tests in patients with coronary artery disease.

A comparative assessment of regional coronary flow reserve, quantitative percent diameter coronary stenosis and exercise-induced perfusion and wall motion abnormalities was performed in 39 patients with coronary artery disease. Coronary flow reserve was determined by a digital angiographic technique utilizing contrast medium as the hyperemic agent. Percent diameter stenosis was calculated by an automated quantification program applied to orthogonal cineangiograms. Thallium-201 scintigraphy and radionuclide ventriculography were used to assess regional perfusion and wall motion abnormalities, respectively, at rest and during exercise. In Group A, 19 patients without transmural infarction or collateral vessels, coronary flow reserve was inversely related to percent diameter stenosis (r = -0.61, p less than 0.0001), and scintigraphic abnormalities occurred only in vascular distributions with a coronary flow reserve of less than 2.00. There was a strong relation among abnormal regional exercise results, stenoses greater than 50% and reactive hyperemia of less than 2.00. Patients with multivessel disease, however, often had normal exercise scintigrams in regions associated with greater than 50% stenosis and low coronary flow reserve when other regions had a lower coronary flow reserve or higher grade stenosis, or both. In Group B, 20 patients with angiographically visible collateral vessels, 12 of whom had prior myocardial infarction, coronary flow reserve correlated less well with percent diameter stenosis than in Group A (r = -0.47, p less than 0.004). As in Group A patients, there was a significant relation between abnormal exercise test results and stenoses greater than 50%. However, reactive hyperemia values were generally lower than in Group A, and positive exercise stress results were strongly correlated only with highly impaired flow reserves of 1.3 or less. In Group B patients, the coronary flow reserve of vessels with less than 50% stenosis was significantly lower than that of similar vessels in Group A patients (2.40 +/- 0.79 versus 1.56 +/- 0.43; p less than 0.0002). It is concluded that: there is a general relation between quantitative percent diameter stenosis and reactive hyperemia that is not of sufficient precision to allow accurate prediction of coronary flow reserve in individual cases; exercise scintigraphic abnormalities are usually associated with low coronary flow reserve, and the relation between these two functional tests is stronger than the relation between exercise test results and quantitative percent diameter stenosis.(ABSTRACT TRUNCATED AT 400 WORDS)

Aged↗
PubMed1986

Prediction of long-term clinical outcome with final translesional pressure gradient during coronary angioplasty.

The final translesional pressure gradient measured during coronary angioplasty correlates with immediate angiographic and clinical results. Whether the pressure gradient is of value in predicting late clinical outcome has not been determined. We therefore obtained complete follow-up information on 159 patients with single-vessel disease who underwent successful coronary angioplasty. Mean follow-up time was 15 +/- 10 months. The occurrence of repeat angioplasty, coronary bypass surgery, recurrent anginal chest pain, or a positive postangioplasty stress test were considered clinical events indicative of late failure. Of the variables age, gender, initial and final translesional pressure gradient, extent of initial and final arterial narrowing, site of dilatation, type of balloon catheter used, number of inflations, and maximal inflation pressure, only the final translesional pressure gradient was predictive of late failure when analyzed by multivariate techniques. Thus, the final translesional pressure gradient is of value in predicting both immediate and late outcome after coronary angioplasty.

Aged↗
PubMed1985

Validation in dogs of a rapid digital angiographic technique to measure relative coronary blood flow during routine cardiac catheterization.

Assessment of the functional significance of anatomically defined coronary stenoses has been hampered by the lack of clinically applicable techniques of measuring coronary blood flow or flow ratios. A digital angiographic technique is reported that allows rapid analysis of relative regional coronary blood flow during routine cardiac catheterization. This technique was validated in dogs by comparing digital flow ratio estimates with electromagnetic-flow (EMF) ratio measurements. Fourteen open-chest dogs had EMF probes placed on the proximal left anterior descending artery before selective coronary angiography. Electrocardiographically gated images were acquired directly by a digital radiographic system during both baseline blood flow and either contrast or papaverine-induced hyperemia. Dual-parameter functional images were generated using color and intensity coding to represent contrast arrival time and contrast density, respectively. For analysis, myocardial areas of interest were created over the distal perfusion bed of the left anterior descending coronary artery. Mean contrast density/appearance time (CD/AT) values were computer calculated as the mean density divided by the mean arrival time for each. Coronary flow reserve was determined as the ratio of the CD/AT value for a hyperemic image divided by the CD/AT value for the corresponding baseline image. CD/AT ratios correlated well (r = 0.92) with actual EMF ratios (CD/AT Ratio = 0.90 EMF Ratio +0.12, n = 48 ratios). Reproducibility was +/- 13%. Interobserver (r = 0.99) and intraobserver (r = 0.98) variability was excellent. Thus, rapid, accurate and reproducible estimates of relative regional coronary blood flow are possible using digital radiography.

Animals↗
PubMed1985

Relation between graded, subcritical impairments of coronary flow reserve and regional myocardial dysfunction induced by atrial pacing in dogs.

The detection of either impairment of coronary flow reserve at rest or abnormalities of regional myocardial function during an ischemic stress are both means of defining the physiologic significance of coronary stenoses. The relation between these two indexes has not been defined previously, particularly in the setting of mild subtotal impairment of coronary flow reserve. Therefore, this relation was investigated in nine open chest anesthetized dogs. Graded, subcritical coronary stenoses were produced that impaired postocclusion hyperemic flow, but not coronary blood flow at rest. Subendocardial ultrasonic crystals were used to measure segment length shortening at rest and after maximal atrial pacing. There was a curvilinear relation between pacing-induced deterioration of segment length shortening and impairment in reactive hyperemia at rest with the most substantial decrease in regional function occurring when less than 20 to 40% of control reactive hyperemia remained. This corresponded to a reactive hyperemic ratio between 1.7 and 2.3. This nonlinear relation was paralleled by the relation between deterioration of regional function and the percent of control blood flow recorded at the time of regional postpacing dysfunction in the presence of coronary stenosis. It is concluded that coronary flow reserve may be substantially reduced before regional dysfunction induced by atrial pacing becomes pronounced. The extent of regional dysfunction during atrial pacing is, in large part, due to the alterations in coronary blood flow occurring during this form of stress in the presence of coronary stenosis.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1985

Abnormal coronary flow reserve and abnormal radionuclide exercise test results in patients with normal coronary angiograms.

Coronary flow reserve, exercise thallium-201 scintigraphy and exercise radionuclide ventriculography were compared in 18 patients with chest pain and angiographically normal coronary arteries. Regional exercise thallium-201 perfusion was abnormal in three patients, regional exercise wall motion was abnormal in three other patients and results of both tests were abnormal in one additional patient. Left ventricular ejection fraction responses were abnormal in five of these seven patients. The coronary flow reserve of arterial distributions with abnormal perfusion or regional dysfunction was significantly lower than that of distributions associated with normal radionuclide results (1.42 +/- 0.23 versus 2.58 +/- 0.83, p less than 0.001). All patients with abnormal scintigraphic results had low coronary flow reserve (less than 1.95) in at least one distribution. Perfusion abnormalities appeared to be more localized in the arterial distributions with the lowest flow reserve. Only two patients had low flow reserve (less than 1.95) with normal scintigraphic results; both were hypertensive. These data suggest that abnormal exercise scintigraphic findings in patients with angiographically normal coronary arteries and chest pain are indicative of true blood flow or perfusion abnormalities.

Adult↗