bluuebunny/crossref_metadata_2025 huggingface dataset:
Quantitative analysis of contraction band and coagulation necrosis after ischemia and reperfusion in the porcine heart.
Authors: Miyazaki S , Fujiwara H , Onodera T , Kihara Y , Matsuda M , Wu D J , Nakamura Y , Kumada T , Sasayama S , Kawai C
Published: June 2011

To assess the importance of contraction band necrosis (CBN) in reperfusion, CBN, coagulation necrosis (CN), and infarct size, expressed as CBN + CN, were quantitatively analyzed in 25 porcine hearts without collateral circulation. The left anterior descending coronary artery was ligated for 20, 30, 60, and 120 min and then reperfused for 8 hr (groups 1 to 4, respectively). Five hearts were not reperfused (group 5). The areas of CBN and CN were traced at a magnification of X 100 under an inverted microscope and quantified with use of an image analyzer. There was no change in hemodynamics with either occlusion or reperfusion. Regional myocardial blood flow, measured by the generated hydrogen gas clearance method, decreased to almost zero after occlusion but recovered during reperfusion. Percent of risk area infarcted in groups 1 to 4 was 0 +/- 0%, 11 +/- 7%, 80 +/- 9%, and 96 +/- 2%, respectively, and the percent of risk area infarcted in group 4 was the same as that in hearts subjected to permanent occlusion (95 +/- 3%). The percent area of CBN was 100 +/- 0% in group 2, 68 +/- 11% in group 3, 2 +/- 1% in group 4, and 2 +/- 2% in group 5. In group 3, the inner third of the ischemic left ventricular wall showed CN and the middle and outer third CBN. These findings show that in pig hearts without collateral circulation, the transmural infarct, two-thirds of which is occupied by CBN, is evident even when reperfusion is achieved after 1 hr occlusion. Therefore, protection against CBN might reduce infarct size after reperfusion.
Ventricular performance related to transmural filling pressure in clinical cardiac tamponade.
Authors: Boltwood C M
Published: June 2011

In clinical cardiac tamponade, open-catheter intrapericardial pressure (IPP) may be used to estimate left ventricular transmural filling pressure (TMFP). However, it has been suggested recently that right atrial pressure (RAP) is superior to IPP in assessing true extracardiac pressure during pericardial drainage. In 10 patients with subacute cardiac tamponade, pulmonary wedge pressure (PWP), RAP, and IPP were measured along with indexes of systolic function. To test the relative merits of IPP and RAP in assessing true pericardial pressure, three TMFP estimates were analyzed: TMFP1 = (PWP - IPP); TMFP2 = (PWP - 1/3 RAP - 2/3 IPP); and TMFP3 = (PWP - RAP). An accurate TMFP presumably should increase during pericardiocentesis and correlate with left ventricular stroke work. In addition, to test the role of preload variation in pulsus paradoxus, respiratory variation in TMFP was analyzed. In the initial tamponade state, RAP and IPP were essentially equal, so all three TMFP estimates gave equivalent results. For instance, TMFP1 averaged 4 +/- 2 mm Hg but fell to 0.2 +/- 1.3 mm Hg during inspiration (p less than .001 vs expiration) and showed beat-by-beat correlation with pulse arterial pressure. After intermediate pericardiocentesis (280 +/- 160 ml), the IPP of 6 +/- 3 mm Hg fell significantly below the RAP of 10 +/- 3 mm Hg (p less than .001), but with a 570 +/- 320 ml residual effusion suggesting continued IPP measurement accuracy. By complete pericardiocentesis (810 +/- 430 ml) there was a significant increase in TMFP1 to 8 +/- 4 mm Hg (p less than .05 vs tamponade) but not in the TMFP3 of 1 +/- 3 mm Hg. Encompassing tamponade and pericardiocentesis data, left ventricular stroke work index showed positive correlation with TMFP1 (r = .59) and TMFP2 (r = .52) but not with TMFP3. Thus cardiac tamponade often may be diagnosed with a TMFP averaging well above zero, and diastolic equalization of PWP, RAP, and IPP may be a predominantly inspiratory finding ("inspiratory tracking"). This supports the role of preload variation in the genesis of pulsus paradoxus. On the other hand, true pericardial pressure may fall substantially below RAP in the course of pericardial drainage. This may be reconciled with the concept that normal pericardial pressure nearly equals RAP by hypothesizing an increased pericardial capacity in subacute tamponade so that pericardiocentesis produces a state analogous to removal of normal pericardial constraint.
Subaortic fibrous ridge and ventricular septal defect: role of septal malalignment.
Authors: Zielinsky P , Rossi M , Haertel J C , Vitola D , Lucchese F A , Rodrigues R
Published: June 2011

The purpose of this study was to test the hypothesis that the presence of a subaortic ridge associated with a ventricular septal defect (VSD) is related to a malaligned ventricular septum caused by anterior or posterior deviation of the infundibular septum with or without obstructive lesions of the aortic arch. Thirty-two of 295 patients in whom a diagnosis of VSD was made by two-dimensional echocardiography and who were studied from June 1983 to April 1985 presented with a subaortic shelf. Every patient (p less than .00001) had a malalignment type of defect; the defect was produced by anterior deviation of the outlet septum (without compromise of the right ventricular outflow tract) in 28 and by posterior deviation of the infundibular septum in four. The prevalence of a subaortic shelf in the malalignment VSD group was 82% (32/39). Among the 28 patients with a subaortic ridge and anterior deviation of the outlet septum only three had aortic coarctation, but all four patients with subaortic stenosis and posterior infundibular malalignment had obstructive lesions of the aortic arch--coarctation in three and interruption of the aortic arch in one (p less than .001). We conclude that a malalignment type of VSD may be a consistent feature in patients with VSD and associated discrete subaortic stenosis. We also noted a high prevalence of subaortic ridge in the presence of a malalignment VSD and therefore speculate that there may be a common morphogenesis for malalignment VSD, subaortic shelf, and obstructive lesions of the aortic arch.
Noninvasive Doppler echocardiographic evaluation of shunt flow dynamics of the ductus arteriosus.
Authors: Hiraishi S , Horiguchi Y , Misawa H , Oguchi K , Kadoi N , Fujino N , Yashiro K
Published: June 2011

The pulsed Doppler technique was used to record the flow velocity patterns in the ductus arteriosus and the pulmonary artery in 26 patients with either isolated or complicated patent ductus arteriosus (PDA). In all patients, abnormal Doppler signals indicating left-to-right (L-R) or right-to-left shunt flow or both could be obtained at the site of the ductus arteriosus. These Doppler flow patterns determined within the ductus coincided with the direction of ductal flow seen on the contrast two-dimensional echocardiogram. No Doppler signals of shunt flow were demonstrated in any of 42 control subjects. The peak, mean, and diastolic velocities of the L-R shunt flow within the ductus were measured from the ductal flow velocity profiles. With the Doppler-derived measurements of the mean and diastolic velocities, patients with normal pulmonary arterial pressure and those with evidence of pulmonary hypertension could be correctly identified. In addition, the mean velocity of the diastolic antegrade flow portion obtained from the proximal left pulmonary artery, which was related to ductal L-R shunting, was measured in 16 patients with isolated PDA. This Doppler flow determinant showed a good linear correlation with the L-R shunt ratio determined by Fick's method (r = .88, p less than .01). Our technique permits the noninvasive evaluation of shunt flow dynamics in patients with PDA.
Does the quantitative assessment of coronary artery dimensions predict the physiologic significance of a coronary stenosis?
Authors: Zijlstra F , van Ommeren J , Reiber J H , Serruys P W
Published: June 2011

To study the relationship between the quantitatively assessed coronary artery dimensions and the regional coronary flow reserve as measured by digital subtraction cineangiography, we investigated 17 coronary arteries with a single discrete proximal stenosis and 12 normal coronary arteries before and after intracoronary administration of papaverine. Coronary flow reserve was found to be curvilinearly related to minimal luminal cross-sectional area (r = .92, SEE = 0.73) and to percentage area stenosis (r = .92, SEE = 0.74). Normal coronary arteries had a coronary flow reserve of 5.0 (+/- 0.8 [SD]), which differed significantly from the coronary flow reserve of the coronary arteries with obstructive disease, in which values ranging from 0.5 to 3.9 were found. Coronary arteries with a percentage area stenosis between 50% and 70% and a minimal luminal cross-sectional area between 2 and 4.5 mm2 differed significantly (p = .001), with respect to the coronary flow reserve, from coronary arteries with a percentage area stenosis in excess of 70% and a minimal luminal cross-sectional area less than 2 mm2. With the use of hemodynamic equations that describe the pressure loss over a stenosis, a theoretical pressure-flow relationship can be inferred that characterizes the severity of the stenosis. Based on this theoretical pressure-flow relationship, coronary arteries that have a limited coronary flow reserve and critical stenosis (distal coronary perfusion pressure below 40 mm Hg at coronary flow of 3 ml/sec) can be identified with high sensitivity (83%) and specificity (82%). Thus, in coronary artery disease the consequent reduction in coronary flow reserve can be predicted with reasonable accuracy by quantitative assessment of coronary artery dimensions.
A randomized, blinded, placebo-controlled trial of recombinant human tissue-type plasminogen activator in patients with unstable angina pectoris.
Authors: Gold H K , Johns J A , Leinbach R C , Yasuda T , Grossbard E , Zusman R , Collen D
Published: June 2011

Twenty-four patients with unstable angina pectoris, defined as chest pain at rest with transient ST segment deviation of at least 1 mm, were randomly assigned to blinded treatment with either placebo or intravenous recombinant human tissue-type plasminogen activator (rt-PA). Before randomization, all patients were treated with oral beta-blockers, calcium antagonists, nitrates, and continuous intravenous heparin for a monitoring period of 12 to 28 hr. After this monitoring period the 24 patients were randomly assigned to receive either placebo or 1.75 mg/kg intravenous rt-PA given over 12 hr at a rate of 0.75 mg/kg over 1 hr, 0.5 mg/kg over 4 hr, and 0.5 mg/kg over 7 hr. One patient, assigned to receive placebo, developed acute myocardial infarction after randomization but before receiving the study drug. Ischemic events were recorded during a hospital follow-up period of at least 4 days unless a further intervention was indicated or the coronary angiogram was normal. The follow-up period was 7 +/- 5 days (mean +/- SD) after the placebo infusion and 8 +/- 4 days after the infusion of rt-PA. Unstable angina pectoris persisted after the completion of the infusion in six of 11 patients receiving placebo and only one of 12 patients receiving rt-PA (p less than .03). Coronary angiography, performed 38 +/- 19 hr after the infusion, demonstrated subocclusive thrombus in eight of 11 patients receiving placebo but in none of 11 patients treated with rt-PA (p less than .002). One patient on rt-PA refused coronary angiography.(ABSTRACT TRUNCATED AT 250 WORDS)
Recombinant tissue plasminogen activator in patients with pulmonary embolism: correlation of fibrinolytic specificity and efficacy.
Authors: Vaughan D E , Goldhaber S Z , Kim J , Loscalzo J
Published: June 2011

Blood samples from 24 patients who received recombinant human tissue-type plasminogen activator (rt-PA) for angiographically documented acute pulmonary embolism were examined to identify and quantify fibrinolysis. Before and after the intravenous administration of 50 mg rt-PA over a 2 hr period, levels of total fibrinogen, fibrin(ogen) degradation products (FDP), and cross-linked fibrin degradation products (XDP) were measured in each patient. Elevated levels of XDP were found in all patients before treatment (mean 2.0 micrograms/ml, normal less than 0.2 microgram/ml), and these increased 12-fold with treatment. Fibrinogen levels fell 30% and FDP levels increased 24-fold for the entire group of patients. Over this 2 hr period, 10 of 24 patients (responders) demonstrated 25% or greater improvement in the extent of pulmonary artery thrombus as quantified by Urokinase Pulmonary Embolism Trial score, and these patients were found to have a significantly lower XDP/FDP ratio after rt-PA (p less than .04) than those patients who failed to respond. These data suggest that the intravenous administration of pharmacologic doses of rt-PA in patients with pulmonary embolism produces both fibrinolysis and fibrinogenolysis, successful thrombolysis in these patients is associated with a preponderance of fibrinogenolysis over fibrinolysis, the XDP/FDP ratio is a useful indicator of fibrinolytic specificity, and in patients with acute pulmonary embolism the endogenous fibrinolytic pathways are activated, albeit ineffectively, as indicated by the increased circulating XDP levels seen in all 24 patients before the administration of rt-PA.
Preservation of distal coronary perfusion during prolonged balloon inflation with an autoperfusion angioplasty catheter.
Authors: Turi Z G , Campbell C A , Gottimukkala M V , Kloner R A
Published: June 2011

A newly designed balloon coronary angioplasty catheter that allows passive antegrade blood flow during balloon inflation (autoperfusion catheter) was compared with a standard balloon coronary angioplasty catheter. In a randomized sequence, inflations were performed for 3 min in the left circumflex coronary artery of 12 dogs with the standard catheter followed by the autoperfusion catheter or vice versa. During inflation with the standard catheter, the ST segment of standard limb lead II increased from -0.02 +/- 0.03 mV to 0.39 +/- 0.08 mV (p less than .001), whereas during inflation with the autoperfusion catheter the ST segment did not change (-0.03 +/- 0.03 vs -0.01 +/- 0.04 mV; p = NS). Regional myocardial blood flow measured by the radioactive microsphere technique in the posterior subepicardium and subendocardium was 0.12 +/- 0.03 and 0.08 +/- 0.03 ml/min/g, respectively, with the standard catheter as compared with 0.57 +/- 0.08 and 0.61 +/- 0.14 ml/min/g with the autoperfusion catheter (both p less than .01 compared with the standard catheter). Thus, unlike the standard catheter, the autoperfusion catheter allows for inflations up to 3 min in duration without producing deleterious changes in the ST segment or severe reductions in regional myocardial blood flow.
Load-dependent relaxation with late systolic volume steps: servo-pump studies in the intact canine heart.
Authors: Ariel Y , Gaasch W H , Bogen D K , McMahon T A
Published: June 2011

In isolated heart muscle preparations an abrupt increase in load during the latter portion of contraction (at a time when there is little if any potential to develop additional force) causes a premature and more rapid relaxation; this load-dependent relaxation characterizes relaxation in myocardium with normal sarcoplasmic reticulum. The purpose of our study was to assess whether or not the phenomenon of load-dependent relaxation is present in the intact heart and to describe the left ventricular response to abrupt load increments (volume steps) throughout the cardiac cycle. Using a microcomputer-controlled servo-pump attached to the apex of an intact canine heart, we studied the effects of 6 ml steps on left ventricular pressure transients during relaxation. Each volume step was carried out in a single beat with 20 stabilization beats separating the intervention beats; thus, at a heart rate of 120 beats/min, a sequence of 10 intervention beats could be carried out in less than 2 min. By performing the experiments on a single-beat basis (control vs intervention beat), we were able to minimize reflex and other physiologic feedback mechanisms that might alter the results. Studies were performed in five anesthetized dogs. In ejecting beats, an early step (immediately after aortic valve opening) caused an increase (3%) in the duration of systole (the time from the onset of pressure rise to the instant at which left ventricular pressure had declined to one-half its maximal value); in contrast, a late step (just before aortic value closure) caused a decrease (7%) in the duration of systole.(ABSTRACT TRUNCATED AT 250 WORDS)
Balloon dilatation of porcine bioprosthetic valves in the pulmonary position.
Authors: Waldman J D , Schoen F J , Kirkpatrick S E , Mathewson J W , George L , Lamberti J J
Published: June 2011

Balloon dilatation (BD) of bioprosthetic valves was investigated in vivo and in vitro. Four children with stenotic bioprosthetic porcine valves in the pulmonary position underwent BD of the valve 10 to 24 months after its insertion. Average valve gradient was reduced from 47.5 to 27 mm Hg. Obstruction at the conduit-branch pulmonary artery connection became apparent after dilatation of the valve. These distal stenoses were also dilated. BD technique was tested in vitro with the use of nonstenotic valves in fresh conduits. No damage to the valve or to the conduit was found when oversized balloons were used in a standard fashion or intentionally inflated until rupture. It is concluded that conduit replacement may be deferred by balloon dilatation of obstructed biological valves and/or a stenotic conduit-pulmonary artery anastomosis.
Thrombolysis in Myocardial Infarction (TIMI) Trial, Phase I: A comparison between intravenous tissue plasminogen activator and intravenous streptokinase. Clinical findings through hospital discharge.
Authors: Chesebro J H , Knatterud G , Roberts R , Borer J , Cohen L S , Dalen J , Dodge H T , Francis C K , Hillis D , Ludbrook P
Published: June 2011

Intravenous administration of 80 mg of recombinant tissue plasminogen activator (rt-PA, 40, 20, and 20 mg in successive hours) and streptokinase (SK, 1.5 million units over 1 hr) was compared in a double-blind, randomized trial in 290 patients with evolving acute myocardial infarction. These patients entered the trial within 7 hr of the onset of symptoms and underwent baseline coronary arteriography before thrombolytic therapy was instituted. Ninety minutes after the start of thrombolytic therapy, occluded infarct-related arteries had opened in 62% of 113 patients in the rt-PA and 31% of 119 patients in the SK group (p less than .001). Twice as many occluded infarct-related arteries opened after rt-PA compared with SK at the time of each of seven angiograms obtained during the first 90 min after commencing thrombolytic therapy. Regardless of the time from onset of symptoms to treatment, more arteries were opened after rt-PA than SK. The reduction in circulating fibrinogen and plasminogen and the increase in circulating fibrin split products at 3 and 24 hr were significantly less in patients treated with rt-PA than in those treated with SK (p less than .001). The occurrence of bleeding events, administration of blood transfusions, and reocclusion of the infarct-related artery was comparable in the two groups. Thus, in patients with acute myocardial infarction, rt-PA elicited reperfusion in twice as many occluded infarct-related arteries as compared with SK at each of seven serial observations during the first 90 min after onset of treatment.
Changes in blood rheology in patients with stable angina pectoris as a result of coronary artery disease.
Authors: Rainer C , Kawanishi D T , Chandraratna P A , Bauersachs R M , Reid C L , Rahimtoola S H , Meiselman H J
Published: June 2011

We investigated several rheologic variables in 17 patients (11 men, six women, mean age = 52.1 +/- 9.8 years) with chronic stable angina. None took any medication except for sublingual nitroglycerin for 2 weeks before the study, and all had angiographically proven coronary artery disease with no history of myocardial infarction. Rheologic measurements included hematocrit, whole blood and plasma viscosity (750 and 1500 sec-1), degree of red cell aggregation via the zeta sedimentation ratio, and the extent and rate of red cell aggregation after stasis (Myrenne aggregometer). Compared with normal control donors, salient observations in the patients as a group included: a small (6%) but significant increase in hematocrit, a significant elevation in plasma viscosity (9%), significant increases in whole blood viscosity at both shear rates (14% and 16%), significant increases in the degree (12%), the extent (41%), and the rate (28% faster time constant) of red cell aggregation, an elevated alpha 2 level (15% increase) and a significantly increased fibrinogen concentration (25% increase), both of which correlated with the enhanced red cell aggregation. Rheologic abnormalities were evident when patients with disease in either one vessel or two to three vessels were compared with controls, but differences between these subgroups of patients were not significant. We conclude that patients with angina have rheologic abnormalities that are compatible with disturbed blood flow and an enhanced tendency for coronary arterial thrombosis.
Efficacy of platelet depletion in counteracting the detrimental effect of acute hypercholesterolemia on infarct size and the no-reflow phenomenon in rabbits undergoing coronary artery occlusion-reperfusion.
Authors: Golino P , Maroko P R , Carew T E
Published: June 2011

It has recently been demonstrated that acute hypercholesterolemia per se, independently of its atherogenic effect, increases the extent of myocardial injury in rabbits undergoing coronary artery occlusion-reperfusion. Estimation of myocardial blood flow after reperfusion indicated that this deleterious effect was due to a vascular obstruction that limited the efficacy of reperfusion. The goal of this study was to evaluate the role played by platelets in contributing to the occurrence of this deleterious effect. Accordingly, New Zealand White rabbits were fed a standard laboratory chow diet (plasma cholesterol 67 +/- 12 mg/dl) or a 2% cholesterol-enriched diet for 3 days (plasma cholesterol 329 +/- 70 mg/dl). In a first series of experiments autologous platelets were labeled with 111In-oxine. After labeling, platelets were reinjected in the same animal and 30 min later coronary artery occlusion (CAO) was induced. CAO was maintained for 30 min followed by 5.5 hr of reperfusion. The animals were then killed, their hearts were excised, and each left ventricle was divided into ischemic and normally perfused samples. Myocardial samples were then counted in a gamma counter. Platelet accumulation ratio, i.e., 111In activity in the ischemic myocardium per gram of tissue divided by 111In activity in the normal myocardium per gram of tissue, was calculated. The ratio was 2.4 +/- 0.2 (mean +/- SEM) in controls (n = 7) and 10.3 +/- 1.0 in the cholesterol-fed group (n = 6, p less than .001), indicating that a marked accumulation of platelets occurs in the ischemic myocardium of hypercholesterolemic rabbits. To evaluate the importance of this phenomenon, another series of experiments was performed.(ABSTRACT TRUNCATED AT 250 WORDS)
Preferential increase in subendocardial perfusion produced by endothelium-dependent vasodilators.
Authors: Pelc L R , Gross G J , Warltier D C
Published: June 2011

The transmural distribution of myocardial blood flow across the left ventricles of anesthetized dogs was measured with radioactive microspheres during intracoronary infusion of the endothelium-dependent vasodilators acetylcholine (10 micrograms/min), adenosine triphosphate (ATP; 20 micrograms/min), and arachidonic acid (600 micrograms/min) and the endothelium-independent vasodilator nifedipine (5 micrograms/min). These compounds were administered before and after a 30 min intracoronary infusion of the phospholipase A2 inhibitor quinacrine (300 micrograms/min). Acetylcholine, ATP, and arachidonic acid produced significant (p less than .05) increases in transmural blood flow and in the ratio of subendocardial to subepicardial blood flow (endo/epi) when compared with control. Infusion of quinacrine did not affect this ratio and did not block the increase in transmural blood flow produced by each agent; however, it did block the redistribution of flow to the subendocardium. In contrast, there was no change in endo/epi during intracoronary infusion of nifedipine before and after quinacrine. These results suggest that endothelium-dependent vasodilators produce a preferential increase in subendocardial perfusion via a product of unsaturated fatty acid metabolism.
Left ventricular end-systolic volume as the major determinant of survival after recovery from myocardial infarction.
Authors: White H D , Norris R M , Brown M A , Brandt P W , Whitlock R M , Wild C J
Published: June 2011

Impairment of left ventricular function is the major predictor of mortality after acute myocardial infarction, but it is not known whether this is best described by ejection fraction or by end-systolic or end-diastolic volume. We measured volumes, ejection fractions, and severity of coronary arterial occlusions and stenoses in 605 male patients under 60 years of age at 1 to 2 months after a first (n = 443) or recurrent (n = 162) myocardial infarction and followed these patients for a mean of 78 months for survivors (range 15 to 165 months). There were 101 cardiac deaths, 71 (70%) of which were sudden (instantaneous or found dead). Multivariate analysis with log rank testing and the Cox proportional hazards model showed that end-systolic volume (chi 2 = 82.9) had greater predictive value for survival than end-diastolic volume (chi 2 = 59.0) or ejection fraction (chi 2 = 46.6), whereas stepwise analysis showed that once the relationship between survival and end-systolic volume had been fitted, there was no additional significant predictive information in either end-diastolic volume or ejection fraction. Severity of coronary occlusions and stenoses showed additional prediction of only borderline significance (p = .04 in one analysis), but continued cigarette smoking did remain an independent risk factor after stepwise analysis. For a subset of patients (n = 200) who had taken part in a randomized trial of coronary artery surgery after recovery from infarction, surgical "intention to treat" showed no predictive value.(ABSTRACT TRUNCATED AT 250 WORDS)
Early postoperative changes in left ventricular chamber size, architecture, and function in aortic stenosis and aortic regurgitation and their relation to intraoperative changes in afterload: a prospective two-dimensional echocardiographic study.
Authors: Sutton M , Plappert T , Spiegel A , Raichlen J , Douglas P , Reichek N , Edmunds L
Published: June 2011

We prospectively studied 16 patients with isolated aortic stenosis and eight with isolated aortic regurgitation undergoing aortic valve replacement, using two-dimensional echocardiography preoperatively, intraoperatively, and 41 +/- 7 days postoperatively to calculate the intraoperative change in afterload, quantify the postoperative changes in left ventricular chamber size, architecture, load and function, determine whether the postoperative left ventricular remodeling correlated with the intraoperative change in afterload in aortic stenosis and aortic regurgitation, and assess whether preoperative afterload excess precluded postoperative improvement in left ventricular function. Preoperative left ventricular mass, end-systolic meridional and circumferential wall stresses, ejection fraction, and stress-shortening relations in patients with aortic stenosis and aortic regurgitation were similar. However, our patients with aortic regurgitation had severe systolic dysfunction, with ejection fraction less than 55% in all but one patient, compared with only 10 of 16 patients with aortic stenosis. Left ventricular end-diastolic volume, mass/volume ratio, and chamber shape were significantly different in patients with aortic stenosis and aortic regurgitation (174 +/- 64 vs 294 +/- 140 ml, p less than .01; 1.81 +/- 0.63 vs 1.14 +/- 0.18, p less than .01; and 0.59 +/- 0.09 vs 0.69 +/- 0.09, p less than .05, respectively). Intraoperative end-systolic meridional and circumferential stresses fell significantly in patients with aortic stenosis but remained unchanged in those with aortic regurgitation. The changes in left ventricular volume and ejection fraction during early postoperative remodeling (6 weeks) correlated with the intraoperative change in afterload in patients with aortic stenosis. In contrast, there was no intraoperative change in afterload in patients with aortic regurgitation and no significant changes in left ventricular volume, architecture, or function at 6 weeks or at 6 months. The differences in left ventricular remodeling and changes in function between patients with aortic stenosis and aortic regurgitation in the early postoperative period most probably relates to the major difference in intraoperative reduction in afterload, although a contributory role may have been played by the preoperative left ventricular dysfunction in those with aortic regurgitation that was underestimated by measurement of ejection fraction.
In-hospital mortality rates from acute myocardial infarction by race in U.S. hospitals: findings from the National Hospital Discharge Survey.
Authors: Roig E , Castaner A , Simmons B , Patel R , Ford E , Cooper R
Published: June 2011

Mortality rates in the United States from coronary artery disease are higher among blacks than whites at younger ages, with a crossover to lower rates above the age of 70. The factors that determine this crossover of age-specific death rates have not been elucidated. Selection from the black population of younger individuals who are sicker by virtue of being more coronary prone might leave a relatively healthier group of older persons. Support for this hypothesis would consist in part of evidence that coronary artery disease has an earlier onset in the black population. We examined data from the National Hospital Discharge Survey for the years 1973-1984 to determine if age-related differences in case-fatality rates existed between whites and nonwhites. In-hospital case fatality rates were 10% to 70% higher for each of the 10 year age groups for nonwhites up to age 70, at which time a crossover occurred. The median age at death from myocardial infarction was approximately 5 years younger in nonwhites compared with whites. National estimates of hospitalization rates for myocardial infarction from these data likewise suggest that nonwhites receive less health care for coronary artery disease than whites relative to recorded fatal events. The age-specific trends in case-fatality support the hypothesis that a cohort selection effect in part determines the black/white differentials in coronary artery disease. Relative susceptibility of the black and white population is thus not appropriately estimated by age-adjusted rates, but should be examined on an age-specific basis within the framework of selection effects on a cohort.
Indium 111-monoclonal antimyosin antibody imaging in the diagnosis of acute myocarditis.
Authors: Yasuda T , Palacios I F , Dec G W , Fallon J T , Gold H K , Leinbach R C , Strauss H W , Khaw B A , Haber E
Published: June 2011

A definitive diagnosis of myocarditis requires right ventricular biopsy. Despite its specificity, however, right ventricular biopsy may lack sensitivity due to the focal nature of the disease. Because indium 111-monoclonal antimyosin antibody imaging can be used to detect myocardial necrosis, this procedure was performed on 28 patients clinically suspected of having myocarditis, 25 of whom had left ventricular ejection fractions of less than 45%, and the results were compared with those of right ventricular biopsy performed within 48 hr of the scan. Antimyosin scans were positive in nine patients who had evidence of myocarditis on right ventricular biopsy, and negative in 11 who had no evidence of myocarditis by biopsy. The remaining eight had positive antimyosin scans but showed no evidence of myocarditis on right ventricular biopsy. On the basis of a right ventricular biopsy standard, the sensitivity of this method was 100%, the specificity 58%. We conclude that antimyosin antibody imaging is a reliable screening method for the evaluation of patients suspected of having myocarditis, and that a positive antimyosin scan indicates the need for right ventricular biopsy to establish the histologic diagnosis.
Denervation supersensitivity of refractoriness in noninfarcted areas apical to transmural myocardial infarction.
Authors: Kammerling J J , Green F J , Watanabe A M , Inoue H , Barber M J , Henry D P , Zipes D P
Published: June 2011

Denervation supersensitivity was demonstrated in anesthetized dogs 5 to 10 days after transmural myocardial infarction produced by latex embolization of a diagonal branch of the left anterior descending coronary artery. Sympathetic efferent denervation in noninfarcted myocardium apical to the infarction was demonstrated by a 90% depletion of myocardial norepinephrine content in the apical (45 +/- 15 pg norepinephrine/g tissue) vs basal (437 +/- 76 pg/g tissue) regions and by the lack of effective refractory period (ERP) shortening during bilateral ansae subclaviae stimulation in 34% of sites apical to the infarction. Supersensitivity in the area apical to the infarction was manifested by an exaggerated shortening of the ERP during both norepinephrine and isoproterenol infusions, with an upward and leftward shift in the dose-response curves in the apical vs basal regions (p less than .001). The cellular mechanism for denervation supersensitivity did not involve detectable changes in the beta-adrenergic receptor adenylate cyclase system. There was no difference in the density of beta-adrenergic receptors ([125I]-cyanopindolol) in the apical (268.6 +/- 22.7 fmol/mg protein) vs the basal (253.5 +/- 24.8 fmol/mg protein) regions. Adenylate cyclase activity stimulated by guanosine triphosphate plus isoproterenol was slightly greater in the apical (58.7 +/- 17.4%) than in the basal (49.6 +/- 10.9%) region, but this difference did not reach statistical significance (p = .068). Muscarinic modulation of beta-receptor coupling (oxotremorine attenuation of guanosine triphosphate plus isoproterenol-stimulated adenylate cyclase activity) also was not significantly different at the apical (31.6 +/- 17.5% inhibition) and basal (21.4 +/- 20.9% inhibition) sites. These data show that a transmural myocardial infarction produces denervation supersensitivity in areas apical to the infarction, but in this preparation no differences in the total number or a redistribution of beta-adrenergic receptors or adenylate cyclase activity were detected.
Diurnal changes in coronary blood flow in conscious dogs.
Authors: Fujita M , Franklin D
Published: June 2011

The purpose of the present study was to evaluate potential diurnal changes in resting coronary blood flow under conditions of comparable myocardial oxygen requirements. We studied 21 conscious, resting dogs instrumented for the measurement of coronary flow, left ventricular pressure, and regional myocardial segment length. Recordings were taken in the early morning and late afternoon. In the afternoon, left circumflex coronary blood flow was 12.8% higher than in the morning, without detectable changes in the major hemodynamic determinants of myocardial oxygen consumption, i.e., heart rate, left ventricular pressure, peak positive dP/dt, end-diastolic regional myocardial dimension, and regional myocardial stroke work. These results are consistent with a circadian variation of coronary vascular tone accompanied by compensatory alteration in myocardial oxygen extraction and may have clinical relevance, since the coronary vascular tone may change dynamically in patients with critical coronary stenosis.
Regulation of low-density lipoprotein receptors: implications for pathogenesis and therapy of hypercholesterolemia and atherosclerosis.
Authors: Goldstein J L , Brown M S
Published: June 2011

Low-density lipoprotein (LDL) is the most abundant and the most atherogenic class of cholesterol-carrying lipoproteins in human plasma. The level of plasma LDL is regulated by the LDL receptor, a cell surface glycoprotein that removes LDL from plasma by receptor-mediated endocytosis. Defects in the gene encoding the LDL receptor, which occur in patients with familial hypercholesterolemia, elevate the plasma LDL level and produce premature coronary atherosclerosis. The physiologically important LDL receptors are located primarily in the liver, where their number is regulated by the cholesterol content of the hepatocyte. When the cholesterol content of hepatocytes is raised by ingestion of diets high in saturated fat and cholesterol, LDL receptors fall and plasma LDL levels rise. Conversely, maneuvers that lower the cholesterol content of hepatocytes, such as ingestion of drugs that inhibit cholesterol synthesis (mevinolin or compactin) or prevent the reutilization of bile acids (cholestyramine or colestipol), stimulate LDL receptor production and lower plasma LDL levels. The normal process of receptor regulation can therefore be exploited in powerful and novel ways so as to reverse hypercholesterolemia and prevent atherosclerosis.
Causes of failure and pathologic findings in surgically removed Ionescu-Shiley standard bovine pericardial heart valve bioprostheses: emphasis on progressive structural deterioration.
Authors: Schoen F J , Fernandez J , Gonzalez-Lavin L , Cernaianu A
Published: June 2011

Twenty-three Ionescu-Shiley standard bovine pericardial bioprostheses (15 aortic, seven mitral, and one tricuspid) removed at surgery from 21 adults, 28 to 75 years old (mean 55 at reoperation), were examined after functioning for as long as 84 months (mean 26). Reoperation was necessitated by active or healed endocarditis (10 valves), paravalvular leak (three), structural deterioration (eight), and other causes (two). Valves with degenerative dysfunction functioned 32 to 84 months (mean 68). Six had intrinsic cuspal calcification, one with stenosis, and there was regurgitation through secondary cuspal defects in five. Six valves had cuspal defects clearly associated with commissural sutures ("alignment stitches") unique to this valve design. One valve had a large basal cuspal tear. Other prominent pathologic features included gross cuspal thickening and mild stretching and microscopic deep fluid insudation, separation of collagen bundles, and mononuclear inflammation. Thus, structural disruption due to calcific tissue degeneration and design-related cuspal tears or commissural perforations are the predominant modes of degenerative failure of Ionescu-Shiley standard bovine pericardial valves.
Conduction over an isthmus of atrial myocardium in vivo: a possible model of Wolff-Parkinson-White syndrome.
Authors: Inoue H , Zipes D P
Published: June 2011

Antiarrhythmic drugs appear preferentially to prolong refractoriness of accessory pathways compared with atrial or ventricular muscle in patients with the Wolff-Parkinson-White syndrome. This response may be due to intrinsic properties of accessory pathways or to depressed conduction associated with a narrow strip, or isthmus, of tissue. To test the latter possibility, in 16 anesthetized dogs we surgically isolated a portion of the right atrial myocardium in the form of an ellipse (10 to 25 X 8 to 15 mm). The ellipse was connected to the body of the right atrium by a narrow isthmus (cross-sectional area [CSA] 1 to 13.5 mm2) and was perfused by the sinus node artery or its branch. Diastolic threshold (mean +/- SE 0.16 +/- 0.05 vs 0.13 +/- 0.02 mA) and effective refractory period (ERP; 144 +/- 4 vs 139 +/- 5 msec) were the same proximal and distal to the isthmus. In eight dogs, determination of the ERP of the isthmus was limited by the ERP of the atrial tissue proximal and distal to the isthmus, and the CSA of the isthmus in these dogs was significantly larger than that in the remaining seven dogs in which the ERP of the isthmus could be determined (7.4 +/- 1.4 vs 3.2 +/- 0.6 mm2, p less than .05). The shortest pacing cycle length (PCL) with 1:1 conduction from the proximal to the distal segments did not differ from that in the opposite direction in 16 dogs (154 +/- 9 vs 153 +/- 7 msec). The CSA of the isthmus correlated inversely with the shortest PCL with 1:1 conduction in both directions via the isthmus (r = -.84, p less than .01). Vagal stimulation shortened the shortest PCL with 1:1 conduction from the distal to the proximal segment (153 +/- 14 vs 143 +/- 12 msec, p less than .02), but not in the opposite direction. Procainamide (10 to 20 mg/kg iv, serum concentration 8.6 +/- 0.8 micrograms/ml) prolonged the ERP of the proximal site from 145 +/- 5 to 170 +/- 5 msec (p less than .001), the ERP of the distal site from 143 +/- 6 to 168 +/- 6 msec (p less than .001) in 12 dogs, and the shortest PCL with 1:1 conduction (proximal to distal from 149 +/- 8 to 204 +/- 17 msec, p less than .001; distal to proximal from 149 +/- 7 to 197 +/- 12 msec, p less than .001) in 14 dogs.(ABSTRACT TRUNCATED AT 400 WORDS)
The efficacy of intermittent coronary sinus occlusion in the absence of coronary artery collaterals.
Authors: Toggart E J , Nellis S H , Liedtke A J
Published: June 2011

The purpose of this study was to evaluate the efficacy of time-controlled intermittent coronary sinus occlusion (ICSO) in preserving regional and global mechanical function during acute ischemia in an animal preparation without significant arterial collateral vessels. Seventeen (eight control, nine ICSO) swine heart preparations undergoing extracorporeal coronary perfusion in situ were subjected to ligation of the left anterior descending coronary artery (LAD) distal to the first major diagonal branch. Data were obtained before and immediately after coronary artery ligation in both animal groups. ICSO, 15 sec of occlusion alternating with 5 sec of release, was then begun in the treatment group. Additional data were obtained in both control and treatment groups at 15 min intervals for 1 hr starting immediately after coronary artery ligation. Global left ventricular function was assessed by shifts in left ventricular end-diastolic pressure and left ventricular dP/dt with left ventricular systolic pressure maintained at about 100 mm Hg. Regional mechanical function was evaluated with transmurally placed ultrasonic crystals. Pressure was also measured directly in the coronary sinus and LAD distal to the ligature. Regional myocardial blood flow was measured in the ischemic bed using 9 micron diameter radiolabeled microspheres injected before, immediately after, and 60 min after coronary artery ligation in both treated and control animals. LAD mean pressure measured distal to the ligation (less than 16 mm Hg) and ischemic bed myocardial blood flow (less than 0.01 ml/g/min) confirmed the absence of significant arterial-arterial collaterals in this preparation. Mean coronary sinus pressure increased significantly (p less than .001) in treated animals during ICSO (e.g., 11.2 +/- 1.6 to 66.2 +/- 10.0 mm Hg at 15 min after coronary ligation). Mean LAD pressure distal to the coronary ligature also increased during ICSO (14.2 +/- 1.2 to 26.8 +/- 1.6 mm Hg), with a similar but delayed rate of pressure rise. No significant differences in left ventricular end-diastolic pressure or left ventricular dP/dt were noted between control or treated animals after coronary ligation. Ischemic bed systolic wall thickening, present before coronary ligation, was not present after occlusion and was not improved during intermittent coronary sinus occlusion in the treatment group. We conclude that in an animal preparation without significant collateral circulation, intermittent coronary sinus occlusion is incapable of restoring regional or global left ventricular mechanical function during conditions of acute ischemia.
Beat-to-beat changes in atrioventricular nodal excitability and its modulation by concealed conduction during functional 2:1 block in man.
Authors: Steinman R T , Lehmann M H
Published: June 2011

An atrial pacing model of functional 2:1 block was used in 10 patients to investigate for the first time the electrophysiologic properties of the human atrioventricular node during intermittent conduction. By varying the terminal portion of the 2:1 atrial train and using the extrastimulus technique, we characterized atrioventricular nodal (AVN) conduction and refractoriness after five different methods of AVN activation: a conducted beat (method I), a conducted beat with omission of the prior blocked beat (method II), a blocked beat (method III), a blocked beat "converted" to one that conducts by omission of the prior conducted beat (method IV), and finally, 1:1 conduction at twice the cycle length of the 2:1 train (control method V). Observed AVN conduction times obeyed the following relationship: method I greater than method II greater than method V, indicating a cumulative effect of concealed penetration by the blocked beats. During 2:1 block, the AVN effective refractory period (ERP) alternated with a mean beat-to-beat difference of at least 100 msec, due mostly to marked ERP abbreviation during AVN activation by method III (vs both 2:1 train cycle length and activation by method V). Concealed penetration by the blocked beat prolonged AVN ERP for the propagated beat (vs that with methods II and V), but to a lesser extent than conduction time was increased. Moreover, the AVN recovery curve with method I was displaced upward and to the right compared with that with methods II to V.(ABSTRACT TRUNCATED AT 250 WORDS)
Mechanism of mitral regurgitation in patients with myocardial infarction: a study using real-time two-dimensional Doppler flow imaging and echocardiography.
Authors: Izumi S , Miyatake K , Beppu S , Park Y D , Nagata S , Kinoshita N , Sakakibara H , Nimura Y
Published: June 2011

The aim of the present study was to elucidate the mechanisms of mitral regurgitation accompanying myocardial infarction. Severity and site of mitral regurgitation was evaluated by the real-time two-dimensional Doppler flow imaging technique in 81 patients with old myocardial infarction. The incidence of mitral regurgitation did not depend on the region of infarction. There was, however, a close relationship between the site of regurgitation and the region of infarction. In patients with mitral regurgitation spurting from the posteromedial area of the valve, the inferior wall was involved in infarction without exception and in some of these patients, the posteromedial papillary muscle was also found to be affected by myocardial infarction; in those with regurgitation spurting from the anterolateral area, the anterior wall showed asynergy. On the other hand in patients with mitral regurgitation spurting from the central area, the region of infarction varied. In these patients, however, the larger the diameter of the mitral anulus, the more severe the grade of regurgitation. The extent of asynergy was another factor related to the severity of mitral regurgitation. Both longitudinally and transversely, broad infarction leads to the enlargement of the mitral anulus. However, even if the mitral anulus is not so dilated, severe involvement of either commissural area results in severe mitral regurgitation from the same commissural side. Thus, there are two major causative factors of mitral regurgitation: (1) asynergy of the papillary muscle or the ventricle that results in mitral regurgitation located in the commissural area of the same side as asynergy, and (2) enlargement of mitral anulus, which results in regurgitation from the central area of the orifice.(ABSTRACT TRUNCATED AT 250 WORDS)