bluuebunny/crossref_metadata_2025 huggingface dataset:
Augmentation of regional coronary blood flow by intra-aortic balloon counterpulsation in patients with unstable angina.
Authors: Fuchs R M , Brin K P , Brinker J A , Guzman P A , Heuser R R , Yin F C
Published: June 2011

Intra-aortic balloon counterpulsation is capable of reducing afterload in patients with unstable angina. Whether it is also capable of augmenting coronary blood flow to poststenotic myocardium is controversial. We studied seven patients receiving maximal drug therapy and requiring balloon pumping for unstable angina as balloon volume and assist ratio were altered. All patients had greater than 90% stenosis of the proximal left anterior descending coronary artery. With maximal augmentation (40 cc balloon volume, 1:1 assist ratio) great cardiac vein flow, representing the efflux from the left anterior descending coronary artery bed, rose from a baseline of 52 +/- 20 to 67 +/- 25 ml/min (mean +/- SD, p = .004) and mean aortic diastolic pressure increased from 77 +/- 13 to 99 +/- 33 mm Hg (p = .004). Increased great cardiac vein flow correlated with increased mean aortic diastolic pressure across changes in balloon volumes (off, 20 cc, 30 cc, and 40 cc) and changes in assist ratio (off, 1:4, 1:2, and 1:1) (p = .02). However, the intermediate balloon volumes produced great cardiac vein flows at an intermediate level between full assist and no assist (p less than .05), whereas the intermediate assist ratios did not augment flow. Thus balloon pumping increased flow to a bed fed by collateral vessels or critical stenoses; this increased flow correlated with increased aortic diastolic pressure, indicating probable loss of autoregulatory ability.
Sustained improvement in left ventricular function and mortality by intracoronary streptokinase administration during evolving myocardial infarction.
Authors: Smalling R W , Fuentes F , Matthews M W , Freund G C , Hicks C H , Reduto L A , Walker W E , Sterling R P , Gould K L
Published: June 2011

One hundred eighty-eight patients with acute myocardial infarction were studied prospectively from August 1980 to September 1982. One hundred thirty-six of these patients were entered into a intracoronary streptokinase study after informed consent was obtained. The remaining 52 patients, who either met exclusion criteria for the study or refused to participate, served as a control group and were treated as those in the study group except that they did not undergo emergency cardiac catheterization. Left ventricular function was determined in both groups by gated radionuclide ejection fraction (EF) on admission to the hospital, at discharge, and 6 months after discharge. With successful reperfusion up to 18 hr after onset of chest pain, mean left ventricular function in the study group improved (EF 39 +/- 13% on admission and 46 +/- 12% at discharge; p less than .001). Mean EF in control patients and those not achieving reperfusion did not change from admission to discharge. Mean EF at 6 month follow-up was not significantly different than at discharge in the study group or the control group. Total cardiac mortality in the control group was 19% compared with 10% in the study group (p = .06, NS). When patients admitted in pulmonary edema or shock (Killip class III or IV) were excluded from both groups, total cardiac mortality in the study group was significantly lower (4%) compared with in the control group (12.5%, p less than .05. The administration of intracoronary streptokinase during evolving myocardial infarction up to 18 hr after onset of chest pain may result in decreased mortality and sustained improvement in left ventricular function.
Sustained regional dysfunction produced by prolonged coronary stenosis: gradual recovery after reperfusion.
Authors: Matsuzaki M , Gallagher K P , Kemper W S , White F , Ross J
Published: June 2011

Prolonged nontransmural ischemia was produced and the early and late effects of reperfusion were studied in 10 conscious dogs instrumented over the long term. Five hours of partial circumflex coronary artery stenosis was produced with a hydraulic occluder, followed by gradual release over 20 min, with measurements of left ventricular pressure, regional myocardial function (systolic wall thickening by sonomicrometry), coronary blood flow velocity (pulsed Doppler), and myocardial blood flow (microspheres). During coronary stenosis the occluder was adjusted frequently to maintain a reduction of systolic wall thickening to 50% to 75% of control (average 62.6% of control). Myocardial blood flow in the ischemic area at 4 hr of partial coronary stenosis was reduced in the inner layers of the myocardium (subendocardium, from 0.81 +/- 0.18 at control to 0.36 +/- 0.08 SD, p less than .01; midwall, from 0.77 +/- 0.20 to 0.46 +/- 0.07 ml/min/g, p less than .01), accompanied by significant ST segment elevation on the subendocardial electrogram (0.83 +/- 0.96 to 4.58 +/- 4.10 mV; p less than .05) and decreased left ventricular dP/dt (3503 +/- 462 to 2991 +/- 339 mm Hg/sec; p less than .01). Within a few minutes after complete release of partial coronary stenosis, ST segments returned to control and myocardial blood flow of the inner layers was increased (subendocardium, 1.37 +/- 0.39, p less than .01; midwall, 0.97 +/- 0.28, p less than .05), but systolic wall thickening and left ventricular dP/dt were significantly depressed and remained reduced at 24, 48, and 72 hr when myocardial blood flow was normal. By seven days, systolic wall thickening and left ventricular dP/dt had returned to control (94.1 +/- 7.0% of control, 3353 +/- 605 mm Hg/sec, respectively; NS). Histologic changes caused by ischemia constituted only 2.7% (average) of the tissue between the crystals in the ischemic wall, but ischemic damage in the posterior papillary muscle, which did not contain crystals, was 31.9%. Thus, regional myocardial dysfunction reduced by nontransmural ischemia for 5 hr persisted for at least 3 days, with only slight damage to the left ventricular free wall but considerable infarction of the posterior papillary muscle. Full recovery of regional and global contractile function of the free wall then occurred within a period of 1 week.
Evidence that ischemic cell death begins in the subendocardium independent of variations in collateral flow or wall tension.
Authors: Lowe J E , Cummings R G , Adams D H , Hull-Ryde E A
Published: June 2011

Irreversible ischemic injury occurs after coronary artery occlusion in vivo, first in the subendocardium and progressing toward the subepicardium over time, presumably due to transmural variations in collateral flow or wall tension. In this study, 10 left ventricular globally ischemic slabs were created that were free of wall tension and collateral flow. The onset and completion of ischemic contracture were identified by means of a new tissue compressibility gauge designed for these studies. Transmural samples were obtained at 15 min intervals for determination of high-energy nucleotide levels and for ultrastructural analysis. The results show that there is a statistically significant gradient of ATP depletion, with the subendocardium consistently showing accelerated energy utilization compared with the subepicardium (p less than .05). Ultrastructural evidence of irreversible injury first appeared in the subendocardium at the onset of ischemic contracture and occurred when ATP levels declined to less than 1 mumol/g wet weight. In summary, these data show that during total ischemia in vitro, cell death begins in the subendocardium at the onset of ischemic contracture and progresses toward the subepicardium over time. These changes occurred independent of variations in collateral flow or wall tension. The results suggest that the increased risk of the subendocardium to ischemic injury previously noted in vivo may occur not only because of variations in collateral flow and wall tension, but may also be secondary to an increased metabolic rate of the subendocardium resulting in faster ATP use during the period of ischemia.
Effects of aging on changing arterial compliance and left ventricular load in a northern Chinese urban community.
Authors: Avolio A P , Chen S G , Wang R P , Zhang C L , Li M F , O'Rourke M F
Published: June 2011

Pulse wave velocity (PWV) was measured by means of transcutaneous Doppler techniques in the aorta, right arm, and right leg of 480 normal subjects of both sexes in urban Beijing, China (age range 3 to 89 years, mean age 41 +/- 20.8 SD); supine blood pressure was recorded in the brachial artery of each subject with standard sphygmomanometric procedures. Serum cholesterol was determined in a subgroup of 79 subjects (age 17 to 85 years, mean 47 +/- 26 SD). PWV (y in cm/sec) was found to vary with age (x, years) at each of the three locations according to the following regression equations: aorta, y = 9.2x + 615, r = .673 (p less than .001); right arm, y = 4.8x + 998, r = .453 (p less than .001); right leg, y = 5.6x + 791, r = .630 (p less than .001). Systolic, diastolic, mean, and pulse pressures were found to increase with age. PWV also increased with mean supine blood pressure but was not related to serum cholesterol (average 4.49 +/- 0.11 [SEM], mmol/l). Compared with that of Western populations, serum cholesterol tended to be lower at all age groups, systolic pressure higher at ages over 35 years, and PWV higher at all ages. Because change in PWV is directly related to change in arterial compliance, these results indicate that aging and not concomitant atherosclerosis (known to be rare in Asian populations) is the dominant factor associated with reduced arterial compliance and increased left ventricular load in these subjects.
Left main coronary artery stenosis: angiographic determination.
Authors: Cameron A , Kemp H G , Fisher L D , Gosselin A , Judkins M P , Kennedy J W , Lesperance J , Mudd J G , Ryan T J , Silverman J F , Tristani F , Vlietstra R E , Wexler L F
Published: June 2011

Reliability of angiographic assessment of the left main coronary artery segment was evaluated by review of 106 coronary cineangiograms from the Coronary Artery Surgery Study. The films were interpreted by three groups of angiographers: those at a clinical site, those at a quality control site, and those on a study census panel. Among the readings of these three groups, there was 41% to 59% agreement on the severity of the lesion, with 80% agreement on whether the lesion was greater or less than 50%. The severity of lesion, its location, or presence of ectasia or calcium did not affect the discrepancy rate, whereas segments that were unusually short, diffusely diseased, or obscured by overlapping vessels were especially difficult to interpret.
Two-dimensional echocardiographic detection of pulmonary venous channel stenosis after Senning's operation.
Authors: Satomi G , Nakamura K , Takao A , Imai Y
Published: June 2011

Stenosis of the common pulmonary venous (PV) channel after Senning's operation for complete transposition of the great arteries is a serious problem, and a method for noninvasive diagnosis is highly desirable. Therefore, our purpose was to devise a method to diagnose PV channel stenosis noninvasively. The newly created common PV channels were measured and the short-axis views of the left ventricle were observed by means of two-dimensional echocardiography in 16 patients who had undergone Senning's procedure. In seven patients we used the original procedure and in nine patients we used a modified procedure with a pedicled pericardial patch. The shape of the left ventricle became round abruptly when the width of the PV channel decreased below a critical value (a range of 6 to 9 mm). Three patients with a relatively round-shaped left ventricle and a narrow PV channel (below 9 mm) were all confirmed to have PV channel stenosis at reoperation. All of the patients with a wide PV channel (above 10 mm) and a flat-shaped left ventricle were in good condition both clinically and as determined from the catheterization data. After the operation, patients who had tricuspid regurgitation, pulmonary vascular obstruction, or residual left ventricular outflow tract stenosis had a relatively round-shaped left ventricle even though the PV channel was wide enough (above 10 mm). Measurement of the PV channel confirmed the effects of these conditions. Correct diagnosis of PV channel stenosis can therefore be made by observing the shape of the left ventricle and by measuring the PV channel.
Differential effects of diltiazem and nitroprusside on left ventricular function in experimental chronic volume overload.
Authors: Porter C B , Walsh R A , Badke F R , O'Rourke R A
Published: June 2011

To compare the hemodynamic effects of a calcium-channel blocker with those of a conventional vasodilator in the awake preinstrumented dog, diltiazem and nitroprusside were administered in equihypotensive infusions before (decrease in mean aortic pressure by 10%; p less than .001, n = 6) and after (decrease in mean aortic pressure by 12%; p less than .001) chronic volume overload (CVO) produced by an infrarenal aortocaval fistula. Diltiazem had no effect on preload either before or after CVO. The maximal rate of change in left ventricular pressure (dP/dtmax) was unaffected by diltiazem before the aortocaval fistula (decrease in dP/dtmax by 6%; p = NS) but was significantly reduced by calcium-channel blockade after CVO (decrease in dP/dtmax by 22%; p less than .001). By contrast, at matched aortic pressures nitroprusside significantly reduced left ventricular end-diastolic dimension (LVEDD) and pressure (LVEDP) in the same animals before (decrease in LVEDD by 10%, p less than .05; decrease in LVEDP by 7 +/- 2 mm Hg, p less than .001) and after CVO (decrease in LVEDD by 7%, p less than .05; decrease in LVEDP by 5 +/- 2 mm Hg, p less than .001) without altering dP/dtmax. We conclude that the calcium entry blocker diltiazem, unlike conventional vasodilators, may depress left ventricular function in CVO by direct negative inotropic properties in amounts that are without myocardial depressant effects in the presence of normal left ventricular performance.
Plasma and lipoprotein cholesterol and triglyceride concentrations in the Pima Indians: distributions differing from those of Caucasians.
Authors: Howard B V , Davis M P , Pettitt D J , Knowler W C , Bennett P H
Published: June 2011

Plasma and lipoprotein cholesterol and triglyceride concentrations were measured in Pima Indians, a genetically homogeneous population with a high prevalence of obesity and diabetes and a low frequency of coronary heart disease. The data for nondiabetic Pima Indians were compared with those of U.S. Caucasians measured during the Lipid Research Clinics Prevalence Study. Plasma total and low-density lipoprotein (LDL) cholesterol levels in Pima men older than 30 years of age and in women over 25 were lower than those of U.S. Caucasians, and in men the total and LDL cholesterol levels did not increase with age. In Pima male subjects of all ages high-density lipoprotein (HDL) cholesterol levels were lower than that in Caucasian male subjects, and in Pima female subjects HDL cholesterol levels averaged 11 mg/dl lower than those in female Caucasian subjects. On the other hand, plasma triglyceride levels in Pima male subjects up to 35 years of age and in female subjects up to 55 years old were higher than those of Caucasians. Comparison of plasma cholesterol and triglyceride levels in Pima male and female subjects showed the same relationships as those in Caucasians (i.e., higher in male subjects until the older age groups), but Pima male and female subjects had similar HDL cholesterol levels. There was a strong negative correlation between obesity and HDL cholesterol levels in Pimas. Obesity appeared to account for the lower HDL cholesterol levels in Pima male subjects compared with that in Caucasian male subjects, but obesity could not explain the lack of differences between the sexes in HDL levels in the Pimas. Triglyceride levels correlated positively with obesity in the Pimas, but the relationship was not as strong as that reported for Caucasians. The results indicate that there are differences in lipoprotein distributions between Pimas and U.S. Caucasians; the relationship between lipoprotein levels and the incidence of coronary disease in the Pimas must be determined.
Results of coronary artery surgery in patients with poor left ventricular function (CASS).
Authors: Alderman E L , Fisher L D , Litwin P , Kaiser G C , Myers W O , Maynard C , Levine F , Schloss M
Published: June 2011

We identified 420 medically treated and 231 surgically treated patients (coronary graft plus myocardial surgery in 30%) who had severe left ventricular dysfunction manifest by an ejection fraction below 0.36 and markedly abnormal wall motion. Compared with medically treated patients, those treated surgically had more severe angina (56.7% vs 29.0% class III or IV; p less than .001), less heart failure as predominant symptom (11.1% vs 18.8%; p less than .003), more severe coronary disease (66.7% vs 50.2% three-vessel disease; p less than .001), a greater concentration of left main coronary artery lesions greater than 70% (12.6% vs 3.8%: p less than .001), and a greater estimated extent of jeopardized myocardium (p less than .001). Multivariate regression analysis of survival, which adjusts for the above covariates, showed that surgical treatment prolonged survival (p less than .05), although it ranked below severity of heart failure symptoms, age, ejection fraction, and left main stenosis greater than 70% in determining prognosis. Surgical benefit was most apparent for patients with ejection fractions below 0.26 who had a 43% 5 year survival with medical treatment vs 63% with surgery. Surgically treated patients experienced substantial symptomatic benefit compared with medically treated patients if their presenting symptoms were predominantly angina; however, there was no relief of symptoms caused primarily by heart failure. We conclude that patients with predominantly ischemic pain symptoms, despite poor left ventricular function, benefit from surgery; however, operative mortality in this high-risk subset must equal or better the 6.9% obtained in this study.
Range- and azimuth-dependent variability of image texture in two-dimensional echocardiograms.
Authors: Skorton D J , Collins S M , Woskoff S D , Bean J A , Melton H E
Published: June 2011

Regional two-dimensional (2D) echocardiographic amplitude patterns, or image texture, may be of diagnostic importance. Echocardiographic image texture is due in part to acoustic speckle, a complex pattern of interference of reflections from many small scatterers in tissue. The regional speckle pattern appears to be altered in several disorders associated with abnormalities in myocardial structure but also may be altered by a variety of characteristics of the scanning instrument. We hypothesized that quantitative measures of regional 2D echocardiographic image texture would vary as a function of position in range and azimuth within the field of view, even when imaging a uniform ensemble of scatterers. We tested this hypothesis by imaging a tissue-equivalent phantom with two phased-array scanners and two different methods of digitization. We analyzed the texture in several regions of interest separated in range and azimuth and found significant differences in quantitative texture measures as a function of position of the region of interest in the sector field of view (p values .006 to .0001 by multivariate analysis of variance). We found significant regional variability in texture with both scanners and both methods of digitization. We conclude that regional quantitative image texture in 2D echocardiograms varies as a function of range and azimuth, even when imaging a uniform ensemble of scatterers. This variability is related to several physical and instrument-related phenomena and precludes interpreting all regional texture alterations as indicating tissue structural abnormalities.
Selective coronary arteriography in infants and children.
Authors: Takahashi M , Schieber R A , Wishner S H , Ritchie G W , Francis P S
Published: June 2011

The recent increase in incidence of Kawasaki disease with attendant coronary artery aneurysms spurred our interest in developing a technique for selective coronary arteriographic examination of infants and children. Right and left coronary artery catheters were shaped according to the aortic root diameters and ascending aorta lengths predicted from the patient's heights. Thirty-eight studies were done in 34 patients who were 7 months to 18 years of age (median 3.2 years) and no permanent sequelae resulted. Advantages of the use of selective coronary arteriography include the ability to visualize stenoses, important branches, and intercoronary anastomoses. The technique is also useful in evaluation of anomalous coronary arteries, myocardial ischemia, and coronary artery distribution before right ventricular outflow tract reconstruction.
Prospective randomized trial of intravenous and intracoronary streptokinase in acute myocardial infarction.
Authors: Rogers W J , Mantle J A , Hood W P , Baxley W A , Whitlow P L , Reeves R C , Soto B
Published: June 2011

To evaluate the relative thrombolytic efficacy and complications of intracoronary vs high-dose, short-term intravenous streptokinase infusion in patients with acute myocardial infarction, we performed baseline coronary arteriography and then randomly allocated 51 patients with acute myocardial infarction to receive either intracoronary (n = 25) or intravenous (n = 26) streptokinase. Patients getting the drug by the intracoronary route received 240,000 IU of streptokinase into the infarct-related artery over 1 hr, whereas those getting the drug by the intravenous route received either 500,000 IU of streptokinase over 15 min (n = 10) or 1 million IU of streptokinase over 45 min (n = 16). Angiographically observed thrombolysis occurred in 76% (19/25) of the patients receiving intracoronary streptokinase, in 10% (1/10) of the patients receiving 500,000 IU of streptokinase intravenously, and in 44% (7/16) of the patients receiving 1 million IU of streptokinase intravenously. Among patients in whom thrombolysis was observed, mean elapsed time from onset of streptokinase infusion until lysis was 31 +/- 18 min in patients receiving intracoronary streptokinase and 38 +/- 20 min in those receiving intravenous streptokinase (p = NS). Among patients in whom intravenous streptokinase "failed," intracoronary streptokinase in combination with intracoronary guidewire manipulation recanalized only 7% (1/15). Fibrinogen levels within 6 hr after streptokinase were significantly lower in the patients receiving intravenous streptokinase (39 +/- 17 mg/dl) than the levels in those receiving intracoronary streptokinase (88 +/- 70 mg/dl) (p less than .05) but were similar 24 hr after streptokinase in the two groups. Bleeding requiring transfusion occurred in one patient in each group. Thus, in this prospective randomized trial of intracoronary vs intravenous streptokinase, hemorrhagic complications were few, although both regimens produced a systemic lytic state. Although the thrombolytic efficacy of intracoronary streptokinase was superior to that of high-dose, short-term intravenous streptokinase, the higher-dose intravenous regimen (1 million IU over 45 min) achieved thrombolysis in a significant minority (44%) of patients and might be useful therapy for patients not having access to emergency catheterization.
Effects of verapamil on left ventricular systolic and diastolic function in patients with hypertrophic cardiomyopathy: pressure-volume analysis with a nonimaging scintillation probe.
Authors: Bonow R O , Ostrow H G , Rosing D R , Cannon R O , Lipson L C , Maron B J , Kent K M , Bacharach S L , Green M V
Published: June 2011

To investigate the effects of verapamil on left ventricular systolic and diastolic function in patients with hypertrophic cardiomyopathy, we studied 14 patients at catheterization with a nonimaging scintillation probe before and after serial intravenous infusions of low-, medium-, and high-dose verapamil (total dose 0.17 to 0.72 mg/kg). Percent change in radionuclide stroke counts after verapamil correlated well with percent change in thermodilution stroke volume (r = .87), and changes in diastolic and systolic counts were used to assess relative changes in left ventricular volumes after verapamil. Verapamil produced dose-related increases in end-diastolic counts (19 +/- 9% increase; p less than .001), end-systolic counts (91 +/- 54% increase; p less than .001), and stroke counts (7 +/- 10% increase; p less than .02). This was associated with a decrease in ejection fraction (83 +/- 8% control, 73 +/- 10% verapamil; p less than .001) and, in the 10 patients with left ventricular outflow tract gradients, a reduction in gradient (62 +/- 27 mm Hg control, 32 +/- 35 mm Hg verapamil; p less than .01). The end-systolic pressure-volume relation was shifted downward and rightward in all patients, suggesting a negative inotropic effect. In 10 patients, left ventricular pressure-volume loops were constructed with simultaneous micromanometer pressure recordings and the radionuclide time-activity curve. In five patients, verapamil shifted the diastolic pressure-volume curve downward and rightward, demonstrating improved pressure-volume relations despite the negative inotropic effect, and also increased the peak rate of rapid diastolic filling. In the other five patients, the diastolic pressure-volume relation was unaltered by verapamil, and increased end-diastolic volumes occurred at higher end-diastolic pressures; in these patients, the peak rate of left ventricular diastolic filling was not changed by verapamil. The negative inotropic effects of intravenous verapamil are potentially beneficial in patients with hypertrophic cardiomyopathy by decreasing left ventricular contractile function and increasing left ventricular volume. Verapamil also enhances left ventricular diastolic filling and improves diastolic pressure-volume relations in some patients despite its negative inotropic effect.
Long-term prognosis after recovery from myocardial infarction: a nine year follow-up of the Perth Coronary Register.
Authors: Martin C A , Thompson P L , Armstrong B K , Hobbs M S , de Klerk N
Published: June 2011

Patients registered by the 1971 Perth Coronary Register as having suffered a myocardial infarction were followed up for 9 years. The Register was a community-based study that used standard methods and criteria as part of a World Health Organization collaborative investigation. Of the 1078 patients studied, 77% survived the first 24 hr and 62% the first 28 days; 0.3% were lost to follow-up. For the 666 patients alive at 28 days, the crude 1, 5, and 9 year survival rates were 88%, 67%, and 52%, respectively. The relationship between 54 variables and the survival of patients alive 28 days after myocardial infarction was examined by life-table methods and the log rank test, and then by fitting a proportional hazards model to the data. The important prognostic factors were age, sex, past history of myocardial infarction, stroke, diabetes and hypertension, tachycardia at presentation, hypotension at presentation, and the occurrence of arrhythmias as short-term complications. The most appropriate mathematical description of the joint effects of the prognostic factors was a multiplicative model with no interaction.
Effects of diastolic transseptal pressure gradient on ventricular septal position and motion.
Authors: Kingma I , Tyberg J V , Smith E R
Published: June 2011

Despite the clinical prevalence of paradoxic interventricular septal (IVS) motion, its pathogenesis remains unclear. To assess the influence of the end-diastolic transseptal pressure gradient, we studied eight open-chest dogs during right ventricular (RV) volume loading (induced by opening a Dacron shunt between the pulmonary artery [PA] and right atrium), RV pressure loading (constriction of PA), and left bundle branch block (RV pacing). Ultrasonic crystals in the IVS and on the RV and left ventricular (LV) free walls (FW) allowed measurement of RV septal-to-free wall (S-FW) and LVS-FW diameters. Another set measured the anteroposterior (AP) diameter of the LV (LVAP). Two-dimensional and M mode echocardiograms confirmed IVS shape and motion pattern, respectively. RV volume load caused a reduction in mean transseptal end-diastolic pressure gradient from 2.1 to -2.6 mm Hg (p less than .001), with a concomitant increase in mean end-diastolic RVS-FW diameter of 2.5 mm (p less than .001) and a decrease in LVS-FW diameter of 2.8 mm (p less than .001). LVAP was unchanged. Echocardiograms confirmed a leftward IVS shift during diastole with paradoxic systolic motion. PA constriction and RV pacing caused similar directional changes in transseptal end-diastolic pressure gradients and diameters. Compared with control values, shunt opening and PA constriction also caused a small leftward shift of IVS at end-systole. Normalized data from all eight dogs revealed significant (p less than .001) correlations between reduction in LV-RV end-diastolic pressure gradients and increases in RVS-FW (r = .85) and decreases in LVS-FW (r = .80) diameters.(ABSTRACT TRUNCATED AT 250 WORDS)
Reduction of coronary reserve: a mechanism for angina pectoris in patients with arterial hypertension and normal coronary arteries.
Authors: Opherk D , Mall G , Zebe H , Schwarz F , Weihe E , Manthey J , Kübler W
Published: June 2011

The pathogenesis of angina pectoris in patients with left ventricular hypertrophy secondary to arterial hypertension and with normal coronary arteries remains uncertain. We measured coronary blood flow (argon method) in 12 control subjects and in 16 patients with arterial hypertension at rest and after intravenous administration of dipyridamole (0.5 mg/kg). In the patients with arterial hypertension, coronary blood flow response to dipyridamole was markedly reduced (p less than .001 as compared with control values). During coronary vasodilation there was a linear correlation between coronary resistance and left ventricular end-diastolic pressure (r = .67, p less than .001). Left ventricular catheter biopsy specimens did not reveal alterations in myocardial microvasculature. These findings suggest that reduction of coronary reserve may be an important contributor to the pathogenesis of angina pectoris in these patients.
Sustained improvement of cardiac function in patients with congestive heart failure after short-term infusion of dobutamine.
Authors: Liang C S , Sherman L G , Doherty J U , Wellington K , Lee V W , Hood W B
Published: June 2011

Fifteen patients with congestive cardiomyopathy (six idiopathic and nine alcoholic) manifested by heart failure (New York Heart Association class III or IV) were randomly assigned to a protocol in which dobutamine (n = 8) or 5% dextrose in water (n = 7) was infused continuously for 72 hr. The dose of dobutamine was titrated to increase cardiac output to twice the baseline values. The patients were evaluated before infusion, shortly after infusion, and 1, 2, and 4 weeks thereafter. Functional class improved in six of eight dobutamine-treated patients but in only two of seven control patients during the 4 week observation period. Maximal exercise time and left ventricular ejection fraction increased significantly above baseline only in the dobutamine group. However, neither dobutamine nor placebo infusion produced significant changes shortly after infusion in heart rate, cardiac index, or total peripheral vascular resistance at rest or during exercise at similar workloads. The group receiving dobutamine did show a reduction in systemic systolic and pulmonary arterial mean and diastolic pressure at rest (123 +/- 5 to 108 +/- 6, 32 +/- 5, to 24 +/- 3, and 26 +/- 4 to 20 +/- 2 mm Hg, respectively). In addition, total body oxygen consumption during similar workloads was lower after dobutamine infusion than before.(ABSTRACT TRUNCATED AT 250 WORDS)
A comparison of the electrophysiologic effects of intravenous and oral amiodarone in the same patient.
Authors: Wellens H J , Brugada P , Abdollah H , Dassen W R
Published: June 2011

In 12 patients (nine with Wolff-Parkinson-White syndrome and three with ventricular tachycardia) the electrophysiologic effects of intravenous (5 mg/kg body weight in 1 min) and oral (total dose 9800 to 11,200 mg) amiodarone were studied with programmed stimulation of the heart. Intravenous and oral amiodarone had a similar (p less than .05) effect of lengthening on the effective refractory period of the atrioventricular node. Only intravenous amiodarone prolonged (p less than .05) the AH interval. Oral amiodarone was more effective than intravenous amiodarone in lengthening the anterograde effective refractory period of the accessory atrioventricular pathway. Only oral amiodarone prolonged the effective refractory period of atrium and ventricle and the HV interval, all significantly (p less than .05). Intravenous amiodarone slowed (p less than .05) the rate of circus-movement tachycardia in patients with Wolff-Parkinson-White syndrome, and further slowing was observed after oral amiodarone. Termination of tachycardia by intravenous amiodarone predicted prevention of reinitiation of tachycardia during oral amiodarone. These data indicate that intravenous and oral amiodarone do not have the same electrophysiologic effects. It is not clear whether cumulative effects, active metabolites, or both are responsible for these differences.
Imaging and characterization of acute myocardial infarction in vivo by gated nuclear magnetic resonance.
Authors: Wesbey G , Higgins C B , Lanzer P , Botvinick E , Lipton M J
Published: June 2011

Imaging by nuclear magnetic resonance (NMR) techniques has been shown to provide high-contrast resolution between soft tissues and characterization of normal and pathologic tissues by differences in magnetic relaxation times. The current study was designed to determine whether electrocardiogram (ECG)-gated NMR imaging of the canine heart in vivo could distinguish normal from infarcted myocardium without the use of intravenous paramagnetic contrast agents. Seven dogs were studied by ECG-gated NMR imaging in vivo (spin-echo technique) with a 0.35 Tesla superconducting magnet at 2 to 7 days after ligation of the left anterior descending coronary artery. In six of the seven dogs, signal intensity was increased in the anterior wall compared with the remainder of the left ventricle; this region of high signal intensity corresponded to the area of myocardial infarction demonstrated at postmortem examination. The signal intensity of the infarcted region was 66 +/- 27% greater than that of normal myocardium (p less than .01). The T2 (spin-spin) relaxation time was 69 +/- 3% longer in the infarcted myocardium as compared with normal myocardium (p less than .01). The NMR images from the seventh dog had uniform signal intensity throughout the myocardium of the left ventricle. An infarct was not evident on postmortem examination in this dog. Thus gated NMR imaging in vivo by the spin-echo technique displays acute myocardial infarctions as regions of high signal intensity without the use of contrast media. The infarct is characterized by a prolonged T2 relaxation time.
Coagulant activities of platelets in coronary artery disease.
Authors: Rao A K , Mintz P D , Lavine S J , Bove A A , McDonough M T , Spann J F , Walsh P N
Published: June 2011

Platelets have been implicated in the pathogenesis of coronary artery disease, and a number of studies have examined platelet function and coagulation parameters in such patients. We have examined platelet coagulant activities, volumes, and aggregate ratios in 23 patients with chest pain, seven of whom had normal coronary angiograms (group I) and 16 of whom had angiographically proven coronary artery disease (group II). There were no significant differences in the mean values for platelet volume or platelet aggregate ratios between the two groups. The platelet coagulant activities concerned with initiation and the early stages of intrinsic coagulation were significantly increased in patients in group II as compared with those in group I. No significant differences were noted between the two groups with respect to prothrombin time, partial thromboplastin time, and plasma levels of fibrinogen and coagulation factors V and VIII. However, the mean activity in plasma of antithrombin III (but not the level of antithrombin III antigen) was significantly lower in patients of group II compared with group I. Overall, our observations provide evidence for an enhanced contribution of platelets to the intrinsic coagulation system in patients with coronary artery disease. The platelet coagulant hyperactivity noted in these patients may reflect a role of platelets in the pathogenesis of coronary artery disease or may be secondary to the underlying arterial disease.
Coronary blood flow during cardiopulmonary resuscitation in swine.
Authors: Bellamy R F , DeGuzman L R , Pedersen D C
Published: June 2011

Recent papers have raised doubt as to the magnitude of coronary blood flow during closed-chest cardiopulmonary resuscitation. We will describe experiments that concern the methods of coronary flow measurement during cardiopulmonary resuscitation. Nine anesthetized swine were instrumented to allow simultaneous measurements of coronary blood flow by both electromagnetic cuff flow probes and by the radiomicrosphere technique. Cardiac arrest was caused by electrical fibrillation and closed-chest massage was performed by a Thumper (Dixie Medical Inc., Houston). The chest was compressed transversely at a rate of 66 strokes/min. Compression occupied one-half of the massage cycle. Three different Thumper piston strokes were studied: 1.5, 2, and 2.5 inches. Mean aortic pressure and total systemic blood flow measured by the radiomicrosphere technique increased as Thumper piston stroke was lengthened (mean +/- SD): 1.5 inch stroke, 23 +/- 4 mm Hg, 525 +/- 195 ml/min; 2 inch stroke, 33 +/- 5 mm Hg, 692 +/- 202 ml/min; 2.5 inch stroke, 40 +/- 6 mm Hg, 817 +/- 321 ml/min. Both methods of coronary flow measurement (electromagnetic [EMF] and radiomicrosphere [RMS]) gave similar results in technically successful preparations (data expressed as percent prearrest flow mean +/- 1 SD): 1.5 inch stroke, EMF 12 +/- 5%, RMS 16 +/- 5%; 2 inch stroke, EMF 30 +/- 6%, RMS 26 +/- 11%; 2.5 inch stroke, EMF 50 +/- 12%, RMS 40 +/- 20%. The phasic coronary flow signal during closed-chest compression indicated that all perfusion occurred during the relaxation phase of the massage cycle. We concluded that coronary blood flow is demonstrable during closed-chest massage, but that the magnitude is unlikely to be more than a fraction of normal.
Alterations in regional myocardial metabolism, perfusion, and wall motion in Duchenne muscular dystrophy studied by radionuclide imaging.
Authors: Perloff J K , Henze E , Schelbert H R
Published: June 2011

Studies at necropsy have shown that the cardiomyopathy of Duchenne muscular dystrophy selects the posterobasal and contiguous lateral left ventricular (LV) walls as initial and primary sites of myocardial dystrophy in the absence of small-vessel coronary artery disease in these areas. The present investigation was designed chiefly to determine whether a myocardial metabolic abnormality could be identified in these same areas during a patient's life. Positron emission computed tomography was used to study regional LV metabolism with 18F 2-fluorodeoxyglucose, and metabolism and/or perfusion was studied with 13NH3. In addition, all subjects had the following performed: thallium-201 scans, technetium-99m multiple-gated equilibrium blood pool imaging, electrocardiograms, vectorcardiograms, and M mode and two-dimensional echocardiograms. 18F 2-fluorodeoxyglucose activity was selectively increased in the posterobasal and posterolateral walls of the left ventricle in 11 of 12 patients with technically adequate images, indicating accelerated regional exogenous glucose utilization. 13NH3 activity was selectively decreased in the same areas in 13 of 15 patients, indicating either a regional metabolic alteration in uptake and trapping, a reduction in regional blood flow, or both. These data identify a myocardial metabolic abnormality concentrated in specific segments of the LV free wall in living patients with Duchenne dystrophy.
A pulsed Doppler echocardiographic method for calculating pulmonary and systemic blood flow in atrial level shunts: validation studies in animals and initial human experience.
Authors: Valdes-Cruz L M , Horowitz S , Mesel E , Sahn D J , Fisher D C , Larson D
Published: June 2011

The purpose of this study was to assess the accuracy of a quantitative two-dimensional range-gated Doppler echocardiographic method for estimating systemic and pulmonary flows in an open-chest canine preparation with a variable-sized atrial level shunt mimicking an atrial septal defect. In addition, we also report our initial experience with 10 children who had isolated atrial septal defects and who had pulmonary and systemic flow rations (QP:QS) determined by Doppler echocardiography simultaneously with green dye-shunt calculations in the cardiac catheterization laboratory. Ten mongrel dogs weighing 20 to 30 kg were anesthetized, intubated, and mechanically ventilated. Previously calibrated electromagnetic flow probes were placed around the ascending aorta and main pulmonary artery, and an atrial level shunt was created by inserting one-half inch diameter cannulae into the left and right atrial appendages and connecting both cannulae to 3/4 inch tubing that passed through a previously calibrated extracorporeal mechanical roller pump. This permitted quantitation as well as regulation of shunt size and direction. With each step-by-step variation in shunt magnitude, systemic and pulmonary flows were estimated by Doppler echocardiography and were matched to the simultaneous electromagnetic flowmeter recordings. Doppler-estimated systemic blood flow was obtained by imaging and recording Doppler flow velocities in the ascending aorta with the transducer positioned directly over the vessel. Doppler pulmonary flow was obtained by imaging the main pulmonary artery on the short-axis view and by determining flow velocity with the sample volume placed distal to the pulmonic valve.(ABSTRACT TRUNCATED AT 250 WORDS)
The effects of shock energy, propranolol, and verapamil on cardiac damage caused by transthoracic countershock.
Authors: Patton J N , Allen J D , Pantridge J F
Published: June 2011

Myocardial damage by transthoracic countershocks was assessed by observation for electrocardiographic loss of R waves and elevation of ST segments, creatine kinase depletion, and histologic evidence of necrosis in damaged areas, and by excision and examination, 3 days later, of all tissue macroscopically observed to be damaged. When 4000 J of stored energy was passed across the chest of dogs anesthetized with pentobarbital sodium (30 mg/kg), more damage was caused when the energy was divided among 10 shocks than when it was applied in 20 or 40 shocks (at intervals of 0.5 min). The prior intravenous administration of verapamil (1 mg/kg) reduced the weight of damaged shocks. Propranolol (0.4 mg/kg) had no effect. These results give further evidence for the role of calcium accumulation in cardiac necrosis after direct current countershocks. Multiple low-energy shocks cause less cardiac damage than do a few high-energy shocks of similar total energy.
Abnormalities in myocardial perfusion during tachycardia in dogs with left ventricular hypertrophy: metabolic evidence for myocardial ischemia.
Authors: Bache R J , Arentzen C E , Simon A B , Vrobel T R
Published: June 2011

This study tested the hypothesis that in the chronically hypertrophied left ventricle pacing stress may cause abnormalities of perfusion that result in myocardial ischemia. Left ventricular hypertrophy (LVH) was produced by banding the ascending aorta of 10 dogs at 6 weeks of age, and studies were carried out after the animals had reached adulthood and when mean left ventricular/body weight ratio was 74% greater than in eight control dogs. Myocardial blood flow was measured with microspheres during pacing at 100, 200, and 250 beats/min, while aortic and coronary sinus blood samples were obtained for determination of concentrations of lactate and the adenosine metabolites inosine and hypoxanthine. In the control dogs, increasing heart rates were associated with an increase in mean myocardial blood flow while subendocardial flow was maintained at a level equal to or greater than subepicardial flow. Myocardial lactate uptake ranged from +60% to -5%, and adenosine metabolites were not detected in coronary sinus blood (less than 0.5 microM/l). In four dogs that underwent aortic banding no production of lactate or adenosine metabolites was observed at any heart rate; in these animals subendocardial flow was maintained at a level equal to or greater than subepicardial flow at all pacing rates. The remaining six dogs with LVH demonstrated net lactate production significantly greater than control during pacing at 250 beats/min; five of these six animals also produced adenosine metabolites.(ABSTRACT TRUNCATED AT 250 WORDS)
Maintenance of aerobic metabolism during global ischemia with perfluorocarbon cardioplegia improves myocardial preservation.
Authors: Flaherty J T , Jaffin J H , Magovern G J , Kanter K R , Gardner T J , Miceli M V , Jacobus W E
Published: June 2011

We used phosphorus-31 nuclear magnetic resonance to test the ability of a perfluorocarbon blood substitute that has been shown in previous studies to improve oxygen delivery to hypothermic myocardium to maintain aerobic high-energy phosphate metabolism during total global ischemia. Twenty-three isolated perfused rabbit hearts were subjected to 180 min of hypothermic (23 degrees C) global ischemia followed by 45 min of normothermic reperfusion. Hearts received multiple doses of a cardioplegic solution that contained either oxygenated perfluorocarbon (Fluosol O2), nonoxygenated perfluorocarbon (Fluosol N2), or standard crystalloid hyperkalemic cardioplegic solution (STD-KCl) at 30 min intervals. Recovery of isovolumic left ventricular developed pressure (LVDP) was used to assess preservation of contractile function. Recovery of LVDP was 84 +/- 19% of preischemic control values with Fluosol O2, 68 +/- 16% with Fluosol N2, and 67 +/- 17% with STD-KCl (p = .058 vs Fluosol N2 and p = .056 vs STD-KCl). During 3 hr of ischemia intracellular pH (pHi) fell to 6.68 +/- 0.20 with STD-KCl and to 6.71 +/- 0.14 with Fluosol N2 but remained above 7.00 throughout the ischemic period with Fluosol O2 (p less than .0001 vs Fluosol N2 or STD-KCl). Myocardial ATP content was better preserved at 107 +/- 14% of control values with Fluosol O2 compared to 60 +/- 18% of control with Fluosol N2 and 75 +/- 21% of control with STD-KCl (p less than .001 vs Fluosol N2, p = .002 vs STD-KCl). Phosphocreatine (PCr) was also better preserved with Fluosol O2.(ABSTRACT TRUNCATED AT 250 WORDS)