bluuebunny/crossref_metadata_2025 huggingface dataset:
Postoperative exercise response in the evaluation of the physiologic status after coronary bypass surgery.
Authors: Rahimtoola S H
Published: June 2011

Many studies have demonstrated that coronary artery bypass surgery combined with medical therapy produces a greater degree of improvement in the symptomatic state and in the functional class of the patients with severe coronary artery disease than does medical therapy alone. This can be objectively documented by an improvement in the exercise capacity and by an increase in heart rate and blood pressure attained at the higher level of exercise. The improvement is the result of relief of exercise-induced (and resting) myocardial ischemia documented by increases in heart rate and blood pressure, greater lactate extraction across the myocardium, improvement in left ventricular dysfunction, abolition of exertional hypotension, and by reversal of exercise-induced and of resting thallium-201 defects. Results of coronary bypass surgery performed during 1974-1979 are better than those during 1969-1973.
The effects of age, body wight and family relationships on plasma lipoproteins and lipids in men, women and children of randomly selected families.
Authors: Connor S L , Connor W E , Sexton G , Calvin L , Bacon S
Published: June 2011

Two hundred thirty-three families were randomly selected from a designated population base. Data from 619 persons ages 6--65 years had distributions of lipid and anthropometric values typical for the U.S. population. The typical rise in plasma cholesterol and triglyceride with age was also demonstrated. The plasma cholesterol and low-density lipoprotein (LDL) correlated more strongly with age than body weight, whereas the plasma triglyceride was more related to body weight than to age. High-density lipoprotein (HDL) was inversely correlated with weight and plasma triglyceride. Family membership accounted for approximately 20% of the variability in cholesterol, LDL, HDL and weight. Related family members (father-child, mother-child and siblings) had strong correlations for plasma cholesterol, LDL and HDL. These measurements did not correlate in the spouse pairs. The plasma triglyceride did not correlate for the family as a whole nor for the individual family members. This study indicates the importance of both chronic environmental factors and genetic family relationships on plasma lipids and lipoproteins.
Frequency of provoked coronary arterial spasm in 1089 consecutive patients undergoing coronary arteriography.
Authors: Bertrand M E , LaBlanche J M , Tilmant P Y , Thieuleux F A , Delforge M R , Carre A G , Asseman P , Berzin B , Libersa C , Laurent J M
Published: June 2011

We established the incidence of coronary artery spasm provoked by 0.4 mg of methergine in 1089 consecutive patients undergoing coronary angiography. The test was performed after routine coronary arteriography. Subjects included patients with angina, both typical and atypical, patients who had recently had myocardial infarction and patients with either valvular disease or congestive cardiomyopathy. Patients with spontaneous spasm, left main narrowing or severe three-vessel disease were excluded. One hundred thirty-four patients experienced focal spasm. Focal spasm was uncommon in patients with atypical precordial pain (1.2%), angina of effort (4.3%), valvular disease (1.95%) or cardiomyopathy (0%). It occurred most often in patients with angina at rest and less often in patients with angina both at rest and induced by exercise. Spasm was provoked in 20% of patients with recent transmural infarction, but in only 6.2% of patients studied later after infarction. Spasm was superimposed on fixed atherosclerotic lesions in 60% of the patients. No serious complications were encountered. Although the patients who underwent provocation tests in this study are not representative of all patients with coronary artery disease, spasm occurred in 20% of patients who experienced a coronary event and in 15% of patients who complained of chest pain.
Drug-induced conditioning in congestive heart failure.
Authors: Leier C V , Huss P , Lewis R P , Unverferth D V
Published: June 2011

Continuous 72-hour infusions of dobutamine reportedly effect sustained clinical improvement in patients with congestive heart failure. This study was designed to determine if shorter, more frequent infusions, delivered in an outpatient setting, elicit a similar response. Twenty-six patients with moderately severe congestive heart failure were randomized, 11 into a control group and 15 into a dobutamine treatment group. Baseline data were collected for 4 weeks in each group. Thereafter, the dobutamine treatment group received 4-hour infusions of dobutamine weekly for 24 weeks. Systolic time intervals, echocardiography, cardiac index and treadmill exercise tolerance were used to follow the progress of the control and dobutamine treatment groups. The ratio of preejection period to left ventricular ejection time and the cardiac index did not change significantly in either group. The velocity of circumferential fiber shortening and the percent change in the minor axis of the left ventricle during systole improved modestly (p less than 0.05) above baseline in the dobutamine group after 14 weeks of treatment and above the corresponding control values (p less than 0.05) after 22 weeks. Exercise tolerance (duration) improved 25--51% (all p less than 0.05) above baseline in the dobutamine group compared with 10--17% (all p greater than 0.05 vs baseline) in the control group. Heart rate at maximal exercise did not change significantly from baseline for either group and did not differ significantly between the two groups. Functional classification improved in 12 of 15 dobutamine treatment patients and in only two of 11 control patients (p less than 0.05). In our patients with congestive heart failure, weekly 4-hour dobutamine infusions did not elicit a major change in resting left ventricular function; however, exercise performance and clinical status improved considerably.
Expansion of acute myocardial infarction: an experimental study.
Authors: Hochman J S , Bulkley B H
Published: June 2011

Expansion (regional dilatation and thinning) of acutely infarcted myocardium in man has been shown to correlate with overall cardiac dilatation and rupture. We studied gross and histopathologic features and the time course of expansion in rats. Infarcts were produced in 84 rats by ligation of the left coronary artery and studied at 1, 2, 3, 4, 5 and 7 days. All hearts were prepared by potassium diastolic arrest, gel distention and fixation. Expansion was graded 0 to 4+ : 1+, mild thinning of infarcted wall; 2+, mild thinning and dilatation; 3+, moderate thinning and dilatation; and 4+, marked thinning and dilatation. There were 80 transmural infarcts, and 66% showed expansion; 36 of 80 (45%) were graded 1-2+ and 17 of 80 (21%) 3-4+. None of the four exclusively nontransmural infarcts showed expansion. Expansion was present in 61% of transmural infarcts at 1-2 days, in 65% at 3-4 days and in 80% at 5-7 days. The percentage of rats with severe (3-4+) expansion increased markedly over this period, from 0% at 1-2 days to 23% at 3-4 days to 65% at 5-7 days. Histopathologic infarct evolution was roughly twice as rapid as that of humans; 5-7 day-old infarcts showed well-developed granulation tissue. Thus, expansion can be produced in an animal model. A critical infarct size of 17% appeared necessary for significant (greater than 1+) expansion, and the degree of expansion correlated with infarct size. Although this phenomenon begins early after infarction, its extent progresses over days, making interventions to interrupt its development feasible.
Mechanism of abnormal interventricular septal motion during delayed left ventricular activation.
Authors: Little W C , Reeves R C , Arciniegas J , Katholi R E , Rogers E W
Published: June 2011

To evaluate the mechanism of the abnormal motion of the interventricular septum (IVS) seen echocardiographically in some patients with relatively delayed ventricular activation, we simultaneously recorded high-fidelity left and right ventricular pressures and electrograms and echocardiograms of the IVS in nine open-chest dogs. During sinus rhythm and during left IVS pacing, the IVS was activated from left to right, preejection left ventricular pressure exceeded right ventricular pressure, and IVS motion was normal. During right ventricular pacing from the outflow tract, apex, free wall or right IVS was activated from right to left, right ventricular pressure increased before left ventricular pressure and simultaneously there was an abrupt posterior IVS motion. Simultaneous pacing from the right IVS and left ventricular free wall activated the IVS from right to left and produced a normal transseptal preejection pressure gradient and normal IVS motion. Simultaneous pacing from the left IVS and right ventricular free wall activated the IVS from left to right, and produced abrupt preejection posterior IVS motion coincident with an altered transseptal pressure gradient. During right ventricular pacing, IVS motion after the abrupt preejection posterior movement was variable. Anterior motion was associated with a greater asynchrony of right and left ventricular contraction than was normal posterior motion. We conclude that abrupt preejection posterior IVS motion seen with delayed left ventricular activation from right ventricular pacing is due to passive IVS displacement from an altered transseptal pressure gradient, and subsequent IVS motion depends on the degree of asynchrony between right and left ventricular contraction.
Problems and advantages of an observational data base approach to evaluating the effect of therapy on outcome.
Authors: Rosati R A , Lee K L , Califf R M , Pryor D B , Harrell F E
Published: June 2011

In this report, we summarize the strengths and problems of an observational data base approach to evaluating therapy and studying patient outcomes in long-term chronic disease. Because this approach includes a greater spectrum of patients than randomized clinical trials, it offers a definite advantage with regard to the elucidation of prognostic factors and the application of results to specific patients. The major difficulty with the observational data base approach is that the important prognostic factors must be known for treatment comparisons to be valid. Both the observational data base and randomized trial approaches are susceptible to criticism because the multiple comparisons and multiple experiments usually involved make the results of any one study not definitive. Either approach is useful in generating or confirming a hypothesis about particular subgroups. Regardless of the method used, proof that a particular therapy increases survival in any group or subgroup of patients with coronary artery disease usually requires confirmation by multiple studies. Finally, observational data base approach, because it capitalizes on data generated and paid for in the patient care process, offers the most feasible approach for evaluating whether changes in prognosis are occurring over time and whether such changes are independent of the mix of the patient population.
Results of myocardial revascularization: a 12-year experience.
Authors: Cosgrove D M , Loop F D , Sheldon W C
Published: June 2011

All 740 patients who underwent isolated myocardial revascularization procedures from 1967 to 1970 at our institution were compared with the first 1000 patients who underwent similar elective operations each from 1971 to 1979. Data from these 9 years were processed through a computerized cardiovascular information registry. In the 1971-1979 period, the patients were older (median age 57 years, compared with 50 years in the 1967-1970 period), more had multivessel disease (90% vs 44%) and more had ventricular asynergy (54% vs 41%). The number of grafts per patient increased from 1.5 to 2.7, and yet morbidity declined in every category except neurologic deficit. The operative mortality rate was 1.1% from 1967 to 1979 and 1.0% from 1971 to 1979. Graft patency was determined in 475 patients from 1967 to 1970, in 533 patients from 1971, in 519 from 1972, in 540 from 1973 and in 408 from 1974. Patency rates after a mean catheterization interval of 21 months were 77%, 77%, 84%, 87% and 87%, respectively. Five- and 10-year follow-ups were completed for the 1967-1970 series and a 5-year follow-up was completed for 1971, 1972, 1973 and 1974 cohorts. The 5- and 10-year actuarial survival rates for the 1967-1970 series were 89.4% and 77.3%, respectively. The 5-year survival rates for the 1971-1974 series were 91.9%, 93.4%, 92.1% and 91.7%. Abnormal ventricular function and incomplete revascularization adversely influenced the mortality rate (p less than 0.05) in all years. The percentage of asymptomatic patients at 5 years was 66%, 65%, 69%, 67% and 74% for the five patient cohorts. Lower risk and a higher 5-year survival rate are attributable to greater technical experience, changing technology and improved management rather than to selection of lower-risk cases. These 5- and 10-year survival rates compare favorably with the reported results of medical therapy.
Survival after coronary artery bypass surgery in specific patient groups.
Authors: Lawrie G M , Morris G C
Published: June 2011

The results of coronary bypass 5-10 years after operation at the Baylor College of Medicine are reported. The late results demonstrate that good relief of symptoms of angina pectoris persisted in 89% of patients at 10 years of follow-up. An overall annual attrition rate of 3% has been fairly constant through 10 years of follow-up. Graft patency has declined at a rate of about 1% per year after the first year, with patency rates in the 5-10-year interval approaching 80%. Pathologic changes in the vein grafts of intimal proliferation or atherosclerosis appear to pose a limited threat to long-term patency. Although derived from an early experience in which perioperative mortality was relatively high and revascularization incomplete, these favorable long-term results are encouraging.
Survival of coronary artery disease patients with stable pain and normal left ventricular function treated medically or surgically at Duke University.
Authors: Whalen R E , Harrell F E , Lee K L , Rosati R A
Published: June 2011

We evaluated the survival rates of medically and surgically treated patients with one-, two- or three-vessel coronary disease (CAD), stable pain, and normal left ventricular function observed at the Duke University Medical Center over an 11-year period. There was no statistical difference in survival when medical and surgical treatment were compared in patients with one-, two- or three-vessel disease (greater than or equal to 75% vessel occlusion). However, the survival curve of patients with three-vessel disease treated surgically consistently exceeded that of those treated medically over a 7-year follow-up period. This difference was not statistically significant, but suggests the need for further study in this group. When patients with 50% or greater lesions in three vessels, stable angina and normal left ventricular function were evaluated, surgical survival was greater than medical survival, although the difference is not statistically significant. The survival in the Duke medical group is substantially higher than that reported for medical patients in the European Cooperative Trial, which suggests that the significant differences surgical in survival in the European Cooperative Trial were largely due to a lower medical survival than that in the Duke medical group.
The effects of airway pressure on cardiac function in intact dogs and man.
Authors: Rankin J S , Olsen C O , Arentzen C E , Tyson G S , Maier G , Smith P K , Hammon J W , Davis J W , McHale P A , Anderson R W , Sabiston D C
Published: June 2011

Ventilation with positive end-expiratory pressure (PEEP) is associated with reduced cardiac output, but the mechanisms involved are controversial. Possible explanations include increased intrathoracic pressure, reflex changes in myocardial inotropism, pulmonary vascular obstruction and abnormal ventricular interaction. Three types of conscious canine preparations were developed to examine simultaneously each of these factors during ventilation with PEEP. In addition, similar measurements were obtained in patients after cardiac surgical procedures and compared with the results of animal experiments. The primary cause of reduced cardiac output during PEEP appeared to be a diminished end-diastolic volume of the left ventricle, and this appeared to be the result of elevated intrathoracic pressure and increased impedance to blood flow through the lungs. Abnormal interventricular septal shifting and reflex autonomic alterations did not appear to be significant in the normal cardiovascular system. These data provide insight into the cardiac effects of PEEP and emphasize the importance of simultaneous quantification of biventricular performance when assessing cardiopulmonary function.
Left ventricular volume and function during relief of cardiac tamponade in man.
Authors: Grose R , Greenberg M , Steingart R , Cohen M V
Published: June 2011

To determine the causes of cardiac failure during cardiac tamponade in man, we studied left ventricular volume and function in eight patients during pericardiocentesis using gated equilibrium radionuclide ventriculography. In the seven patients with clinical and hemodynamic evidence of cardiac tamponade, end-diastolic and end-systolic volumes increased progressively as the initial 500 ml of fluid were removed; the most marked increase occurred during the removal of the first 200 ml of pericardial fluid. After removal of 500 ml of pericardial fluid, end-diastolic volume increased from 52 +/- 8 ml to 111 +/- 13 ml (p less than 0.05) and end-systolic volume from 17 +/- 5 ml to 34 +/- 7 ml (p less than 0.05). Additional aspiration of fluid resulted in no further changes in left ventricular volume. The ejection fraction averaged 70% before removal of fluid and was unchanged by pericardiocentesis. In the one patient who did not have hemodynamic evidence of tamponade, there were only minor changes in left ventricular volumes and ejection fraction. These data suggest that pump function of the left ventricle is well preserved in cardiac tamponade, and that the diminution in stroke volume and consequent cardiovascular collapse seen in tamponade are due to marked underfilling of the ventricle.
Changes in ventriculoatrial intervals with bundle branch block aberration during reciprocating tachycardia in patients with accessory atrioventricular pathways.
Authors: Kerr C R , Gallagher J J , German L D
Published: June 2011

During reciprocating tachycardia in patients with accessory atrioventricular pathways, the observation of changes in ventriculoatrial (VA) intervals with bundle branch block (BBB) aberration has been used to localize the site of the pathway and prove the participation of the pathway in the tachycardia. In this report we present the changes observed during BBB in 93 patients with single atrioventricular pathways in whom the site of their pathways was subsequently proved at the time of their surgical interruption. In patients with left or right free wall pathways, the minimum VA interval (VA min) increased by 61 +/- 19 msec with ipsilateral BBB, whereas no change occurred with contralateral BBB. The smallest increase in the VA interval was 35 msec. In 14 patients, shortening of the AH intervals resulted in changes in overall cycle length that were less than 35 msec. Patients with septal pathways all had changes in VA min of 25 msec or less with either right or left bundle branch block (RBBB or LBBB), which suggests that a clear differentiation between septal and free wall pathways can be made on the basis of changes in VA min. In patients with anteroseptal pathways, VA min intervals frequently prolonged with RBBB (16 +/- 9 msec) but not with LBBB. In patients with posteroseptal pathways, VA min frequently prolonged with LBBB (13 +/- 8 msec) but not with RBBB. Therefore, the observed changes in VA min with BBB may serve as an important indicator of the site of an accessory pathway and may provide guidance in the choice of surgical therapy.
Long-term results after atrial repair of transposition of the great arteries in early infancy.
Authors: Mahony L , Turley K , Ebert P , Heymann M A
Published: June 2011

Fifty-two patients younger than age 100 days who had an intact interventricular septum or a small ventricular septal defect underwent atrial repair of d-transposition of the great arteries (d-TGA). No patient died. To assess long-term results, we evaluated all 36 patients who had been followed for at least 1.5 years (mean 2.7 years) after surgery. The physical findings, chest roentgenograms, ECGs and echocardiograms were reviewed. Catheterization was done 6-60 months (mean 15 months) after surgery in 28 patients. Growth was normal in all but three patients. Neurologic development was abnormal in six patients (delayed speech in one patient, learning disability in three patients and preoperative cerebral infarction in two patients). The ECG showed sinus rhythm in 24 patients, minor abnormalities in nine and major dysrhythmias in three. Catheterization showed a normal cardiac index in all 28 patients. No intracardiac shunt was detected in 19 of 24 patients in whom complete oximetry data were available. One patient required reoperation for persistent atrial shunt and subsequent pacemaker placement. Two patients required baffle revision for symptoms related to superior vena caval obstruction. Right ventricular end-diastolic pressure was less than 15 mm Hg in all of 18 patients evaluated. We conclude that atrial repair of d-TGA in early infancy can be performed with a low mortality rate and a low incidence of late complications.
Pulmonary atresia and intact ventricular septum: surgical management based on a revised classification.
Authors: de Leval M , Bull C , Stark J , Anderson R H , Taylor J F , Macartney F J
Published: June 2011

Sixty patients with pulmonary atresia and intact ventricular septum (PA:IVS) presenting from 1970 to 1980 are reviewed. Three groups of patient are discussed: those with tripartite right ventricles, those with no trabecular portion to the cavity, and those with neither trabecular nor infundibular portions. The decrease in early mortality for neonates with PA:IVS since 1977 (one death in 15 patients) supports our current management policy of preoperative prostaglandin E1 infusion with transpulmonary valvotomy (for patients with an infundibular cavity) combined with a left modified Blalock-Taussig shunt using a Gore-Tex prosthesis. Tricuspid valve growth, estimated by serial angiograms in 12 patients, was greater if right ventricle-to-pulmonary artery continuity was established. Later definitive repair was attempted in nine patients, with two early deaths; five underwent right ventricular outflow tract reconstruction and four had modified Fontan procedures. Neonates with critical pulmonary stenosis are also discussed. Their neonatal mortality (nine deaths in 20 patients) was similar to that of comparable patients with PA:IVS, but their actuarial survival at 5 years (55%) was superior (36% at 5 years).
Foramen ovale/atrial septum area ratio: a marker of transatrial blood flow.
Authors: Atkins D L , Clark E B , Marvin W J
Published: June 2011

We examined 51 cardiac specimens to test the hypothesis that the size of the foramen ovale is directly proportional to the relative volume of transatrial blood flow during cardiac morphogenesis. Included in the study were 18 normal specimens, five with tricuspid atresia, four with pulmonary atresia and intact ventricular septum, nine with secundum atrial septal defect, eight with simple coarctation of the aorta and seven with aortic stenosis. The areas of the foramen ovale and atrial septum were measured and the ratio of foramen ovale to atrial septum was calculated. The area of the atrial septum did not differ significantly among the six groups. Normal specimens had a ratio of 0.19 +/- 0.07. Specimens with tricuspid atresia and pulmonary atresia had ratios of 0.43 +/- 0.01 and 0.38 +/- 0.10, respectively (p less than 0.05). The ratio in specimens with coarctation of the aorta was 0.15 +/- 0.07 (NS). Specimens with aortic stenosis had a ratio of 0.11 +/- 0.06 (p less than 0.05). Specimens with secundum atrial septal defects had a ratio of 0.37 +/- 0.08 (p less than 0.05). These data indicate that the foramen ovale is a marker of transatrial blood flow in utero. Secundum atrial septal defects may be a consequence of increased transatrial blood flow.
Partial atrioventricular canal defect in adults.
Authors: Hynes J K , Tajik A J , Seward J B , Fuster V , Ritter D G , Brandenburg R O , Puga F J , Danielson G K , McGoon D C
Published: June 2011

Between March 1955 and March 1981, 52 adult patients (age 20 years or older) with partial atrioventricular canal (PAVC) were examined at the Mayo Clinic. Forty patients were in New York Heart Association (NYHA) functional class I or II. The ECG showed right bundle branch block with left-axis deviation in 48, first-degree atrioventricular block in 33 and atrial fibrillation in nine. Preoperative catheterization was done in 37 patients; the mean pulmonary resistance index was 2.8 U.m2, and the mean pulmonary-to-systemic flow ratio was 3.0. Forty-seven patients underwent operation; two required mitral valve replacement. There were three operative deaths (6.4% operative mortality) and two late deaths. All surviving patients were in NYHA class I or II. No patient required subsequent permanent pacemaker implantation. We conclude that repair of PAVC in adults may be performed at low risk and may improve patient longevity and functional status.
Relative lack of coronary blood flow during closed-chest resuscitation in dogs.
Authors: Ditchey R V , Winkler J V , Rhodes C A
Published: June 2011

Recent studies have shown that blood flow during closed-chest cardiopulmonary resuscitation (CPR) results primarily from generalized changes in intrathoracic pressure rather than direct compression of the heart. Since ascending aortic and right atrial pressures rise and fall synchronously and to comparable levels during CPR, we hypothesized that the absence of a pressure difference across the coronary vascular bed during CPR precludes coronary blood flow. To test this hypothesis, we compared high-fidelity ascending aortic and right atrial pressures and carotid and coronary blood flow (electromagnetic flowmeters) during closed-chest CPR in 12 fibrillating dogs. Chest compression force was increased from 40 to 140 pounds in 20-pound increments using a pneumatic chest compression device. Although ascending aortic and right atrial pressures were always similar, high-compression-force CPR produced small mean pressure differences across the coronary vascular bed (5.6 +/- 0.8 mm Hg [+/- SEM] at 140 pounds). These pressure differences were accompanied by low levels of coronary blood flow. However, coronary flow was less than 1% control (prearrest) values whenever chest compression force was less than 100 pounds, and carotid flow exceeded coronary flow under all conditions (carotid and coronary flows at 140 pounds = 26.2 +/- 6.4% and 4.3 +/- 2.0% of prearrest values, respectively, p less than 0.01). We conclude that generalized changes in intrathoracic vascular pressures during closed-chest CPR promote carotid but not coronary blood flow. High-compression-force CPR produces small pressure differences across the coronary vascular bed, allowing low levels of coronary flow. However, even high-compression-force CPR is over six times more effective in maintaining carotid flow than coronary flow.
Native collaterals in the development of collateral circulation after chronic coronary stenosis in mongrel dogs.
Authors: Schwarz F , Wagner H O , Sesto M , Hofmann M , Schaper W , Kübler W
Published: June 2011

The response of native collateral circulation to chronic stenosis of the left circumflex coronary artery (LCx) was studied in 17 mongrel dogs. Stenosis restricted reactive hyperemia of the LCx without affecting resting flow. Regional myocardial blood flow was measured by the tracer microsphere technique. Coronary collateral blood flow to the LCx was determined during maximal reactive hyperemia of the left anterior descending branch before and 5 weeks after implantation of a fixed LCx stenosis in the open-chest preparation. The protective effect of collaterals was tested by LCx ligation 5 weeks after implantation of stenosis. Presence of acute myocardial infarction was determined by nitroblue tetrazolium staining. Eleven dogs had a myocardial infarction (group A), but six dogs showed no evidence of infarction at autopsy (group B). In group A, collateral flow and minimal coronary resistance of the LCx bed changed little after LCx stenosis, from 12 to 15 ml/min/100 g and from 10.5 to 10.0 mm Hg/ml/min/100 g, respectively (both p less than 0.05). In contrast, collateral flow in group B increased from 22 to 102 ml/min/100 g (p less than 0.05), and minimal coronary resistance of the LCx bed decreased from 4.8 to 1.4 mm Hg/ml/min/100 g (p less than 0.01). Group A had lower native collateral flow (p less than 0.05) and higher native minimal coronary resistance of the LCx bed than group B (p less than 0.05). Postobstructive LCx pressure correlated well with blood flow data. The LCx risk region was of comparable size in groups A and B, 36.4% vs 39.0% of total left ventricle (p greater than 0.05). Two responses of collateral circulation to chronic stenosis were documented: lack of collateral growth in group A, but significant collateral growth in group B. The natural variation of collateral circulation was the major determinant of the different responses that were important with stenosis of a major coronary artery.
Microvascular spasm in the cardiomyopathic Syrian hamster: a preventable cause of focal myocardial necrosis.
Authors: Factor S M , Minase T , Cho S , Dominitz R , Sonnenblick E H
Published: June 2011

The cardiomyopathic Syrian hamster develops focal myocardial necrosis beginning at 1 month of age, which leads to eventual ventricular failure within 1 year. The pathogenesis of this myocytolytic necrosis is unknown. Based on the nature of the cell necrosis, cytochemical evidence of vascular alterations, and the sensitivity of the hamsters to catecholamines and other vasoactive substances, we believe that the cardiomyopathy may be mediated by abnormalities of the microcirculation. Nonetheless, until the present study, no significant changes have been observed in these vessels. To elucidate the pathogenesis of this disease, we perfused living cardiomyopathic hamsters with silicone rubber solutions, which revealed numerous areas of microvascular constriction, diffuse vessel narrowing and luminal irregularity. Fixed structural lesions in these vessels could not be demonstrated. Pretreatment of young hamsters with verapamil during the period when they normally develop myocardial necrosis prevented myocytolytic lesions and abolished microvascular hyperreactivity. We believe that focal, transient spasm of small blood vessels, probably secondary to vasoactive substances, may cause myocytolytic necrosis (a form of reperfusion injury) in this model. This may also be a multifactorial disease with myocellular as well as vascular abnormalities leading to myocardial degeneration. The similarity of this disease to human and experimental cardiomyopathy suggests that microvascular spasm may be a common denominator of many different cardiomyopathic syndromes.
An animal model of congestive (dilated) cardiomyopathy: dilatation and hypertrophy of the heart in the chronic stage in DBA/2 mice with myocarditis caused by encephalomyocarditis virus.
Authors: Matsumori A , Kawai C
Published: June 2011

To investigate whether lesions that develop in the chronic stage of viral myocarditis are similar to those seen in congestive (dilated) cardiomyopathy, we studied myocarditis in inbred strains of DBA/2 mice infected with encephalomyocarditis (EMC) virus. Myocardial necrosis with calcification appeared on day 4. Thereafter, myocardial necrosis became more extensive and mononuclear cell infiltration was evident and was most marked on day 14. On day 90, cellular infiltration had decreased and myocardial fibrosis was prominent. At this stage, the heart weight was significantly greater in the infected mice than in the controls (0.190 +/- 0.028 g vs 0.122 +/- 0.013 g, mean +/- SD) (p less than 0.001) and the cavity dimensions of the left ventricle were larger (1.67 +/- 0.29 mm vs 1.11 +/- 0.20 mm) (p less than 0.001). The diameters of myocardial fibers of the right ventricle, the interventricular septum and the left ventricle were significantly larger than those of the controls (right ventricle, 16.6 +/- 1.8 vs 13.4 +/- 1.5 micrometer; interventricular septum, 17.8 +/- 1.5 vs 13.8 +/- 1.5 micrometer; left ventricle, 19.4 +/- 1.7 vs 14.8 +/- 1.1 micrometer) (p less than 0.001). This study demonstrates that in viral myocarditis in the chronic stage, lesions develop that resemble those seen in congestive cardiomyopathy.
Treatment of paroxysmal supraventricular tachycardia in infancy with digitalis, adenosine-5'-triphosphate, and verapamil: a comparative study.
Authors: Greco R , Musto B , Arienzo V , Alborino A , Garofalo S , Marsico F
Published: June 2011

The treatment of paroxysmal supraventricular tachycardia (PSVT) in infancy with digitalis, adenosine triphosphate (ATP) and verapamil is reported. Treatment was successful in about 90% of the patients treated with ATP and verapamil and in 61--71% of the patients treated with digitalis (Lanatoside C). Verapamil terminated the tachycardia within 2 minutes of administration in most instances and ATP in less than 1 minute. Digitalis, however, took as long as 2 hours; it was therefore excluded as the drug of first choice in emergencies, and is better suited for treating patients with poor hemodynamics. Side effects with ATP are common but short-lived. With verapamil, side effects are rare, but may be serious if certain contraindications are not taken into account. Digitalis in the dose used in this trial rarely produced side effects. We conclude that ATP or verapamil is the drug of first choice for quick termination of PSVT in infancy.
Preoperative and postoperative renin levels in coarctation of the aorta.
Authors: Parker F B , Streeten D H , Farrell B , Blackman M S , Sondheimer H M , Anderson G H
Published: June 2011

We studied plasma renin activity (PRA) in eight children before and after surgical correction of aortic coarctation. These eight children underwent a combination of low-sodium diet and diuresis before surgery, and PRA was measured shortly thereafter. Thirty-two to 51 months after successful surgical correction, PRA was measured again. The mean PRA was 21.4 +/- 1.3 ng/ml/hour (+/- SD) preoperatively and 5.5 +/- 1.5 ng/ml/hour postoperatively. These findings provide further evidence of the significance of increased renin-angiotensin activity in patients with aortic coarctation.
Clinical characteristics associated with sudden death in patients with variant angina.
Authors: Miller D D , Waters D D , Szlachcic J , Théroux P
Published: June 2011

After hospital discharge, 114 patients with variant angina were followed for a mean period of 26 months. Six died suddenly and 13 others were resuscitated from sudden cardiac death. The extent of coronary disease and the prevalence of left ventricular dysfunction in these 19 "sudden death" patients were similar to those in the patients who did not experience sudden death ("survivors"). During spontaneous episodes of ST elevation recorded in hospital, 56 of the 114 patients had serious arrhythmias: ventricular fibrillation in two, ventricular tachycardia in 28, ventricular couplets or bigeminy in 17, second- or third-degree atrioventricular block in six and asystole in three. Patients with and those without these arrhythmias during attacks were similar with respect to extent of coronary disease, left ventricular function and most other clinical variables. The maximal ST elevation, however, was higher in the arrhythmia group (7.5 +/- 5.7 vs 3.3 +/- 2.3 mm, p less than 0.01). Serious arrhythmias were detected in 16 of the 19 sudden death patients, compared with 36 of the 86 survivors (p less than 0.01). Sudden death occurred during follow-up in 15 of the 36 patients (42%) with ventricular fibrillation, ventricular tachycardia, high-degree atrioventricular block or asystole during attacks, compared with only four of 69 (6%) without these arrhythmias (p less than 0.001). We conclude that variant angina patients with serious arrhythmias during spontaneous attacks differ from other variant angina patient only in the degree of ischemia during attacks, as reflected by maximal ST elevation, but are at a much higher risk for sudden death.
Two-dimensional echocardiography in experimental coronary stenosis. I. Sensitivity and specificity in detecting transient myocardial dyskinesis: comparison with sonomicrometers.
Authors: Pandian N G , Kerber R E
Published: June 2011

The purpose of this study was to assess the sensitivity and specificity of two-dimensional echocardiography in detecting ischemia-induced transient myocardial dyskinesis. We prepared an open-chest dog model of severe coronary stenosis (90% reduction of circumflex coronary artery diameter) and induced ischemia by acutely raising myocardial oxygen requirements with i.v. isoproterenol and acute aortic constriction. The changes observed with echocardiography were compared with those obtained by intramyocardial sonomicrometers placed side by side or in an endocardial-epicardial orientation. Ischemia was defined as systolic wall expansion or thinning on sonomicrometers and two-dimensional echocardiography. We found complete agreement between sonomicrometers and two-dimensional echocardiography in all control tracings and after ischemia was induced; whenever dyskinesis occurred it was seen by both techniques. Although there was qualitative agreement between echocardiographic and sonomicrometric techniques, there were quantitative differences in the assessment of wall thickening. Such differences may be related to malalignment of the sonomicrometers, echocardiographic resolution limitations or other technical factors. We conclude that two-dimensional echocardiography is a sensitive and specific technique for detecting transient myocardial ischemia, and therefore should be useful for demonstrating exercise-induced ischemia in patients with coronary artery disease.
Evaluation of noninvasive tests of cardiac damage in suspected cardiac contusion.
Authors: Potkin R T , Werner J A , Trobaugh G B , Chestnut C H , Carrico C J , Hallstrom A , Cobb L A
Published: June 2011

Nonpenetrating trauma to the chest can result in cardiac damage that may be overlooked because of associated injuries and the lack of obvious thoracic injury. The clinical diagnosis of important cardiac damage in this setting is difficult. We evaluated noninvasive tests for detecting myocardial damage in 100 patients with severe, nonpenetrating chest trauma. The noninvasive tests included serial ECG, serial total CPK and CPK-MB enzymes, continuous Holter monitor recording to detect dysrhythmia, and technetium-99m pyrophosphate scintigraphy. Peak CPK-MB elevations occurred in 72 patients. ECG abnormalities were noted in 70 patients, and 27 patients had Lown grade 3 or greater dysrhythmias. Fifteen patients died and all had autopsies. The noninvasive abnormalities were nonspecific and did not reflect myocardial contusion that led to clinically important cardiac complications.
Thrombolysis in acute myocardial infarction using intracoronary streptokinase: assessment by thallium-201 scintigraphy.
Authors: Schuler G , Schwarz F , Hofmann M , Mehmel H , Manthey J , Mäurer W , Rauch B , Herrmann H J , Kübler W
Published: June 2011

Twenty-one patients with acute myocardial infarction, admitted to the hospital within 4 hours after the onset of symptoms, were studied by seven-pinhole thallium-201 scintigraphy before and 1 hour and 24 hours after intracoronary fibrinolysis using streptokinase. The size of the thallium-201 perfusion defect was assessed from myocardial cross sections reconstructed from the original seven-pinhole data and expressed as a fraction of left ventricular circumference. Recanalization was achieved in 16 patients within 3.9 +/- 1.6 hours after onset of symptoms (group A). In these patients, the size of the perfusion defect had decreased from 36 +/- 17% to 19% +/- 15% (p less than 0.001) at 24 hours. No significant change was detected by redistribution at 1 hour after the intervention. In five patients, intracoronary fibrinolysis was unsuccessful, and the vessel remained occluded (group B). The thallium-201 perfusion defect affected 40 +/- 15% of the left ventricular circumference before the intervention; it remained virtually unchanged at 1 hour (37 +/- 16%) and at 24 hours (41 +/- 15%) after fibrinolysis. The perfusion defect was most reduced in patients with extensive collaterals supplying the ischemic area or with subtotal occlusion of the affected coronary artery. We conclude that successful intracoronary fibrinolysis may reduce the size of the thallium-201 perfusion defect in many patients with acute myocardial infarction. One important factor in the final result may be the presence of residual coronary flow supplied by extensive collaterals or by subtotal occlusion of the affected coronary artery when reperfusion is achieved around 4 hours after the onset of symptoms.
A postscript to Circulation of the blood: men and ideas.
Authors: Riley R L
Published: June 2011

Since 1964, when Fishman and Richards published Circulation of the Blood: Men and Ideas, Guyton's model of the circulation, in which mean circulatory pressure serves as the upstream pressure for venous return, has been extended, and the concept of vascular smooth muscle tone acting like the pressure surrounding a Starling resistor has been postulated. According to this scheme, the positive zero flow intercepts of rapidly determined arterial pressure-flow curves are the effective downstream pressures for arterial flow to different tissues. The arterioles, like Starling resistors, determine the downstream pressures and are followed by abrupt pressure drops, or "waterfalls." Capillary pressures are closely linked to those of the venules into which they flow. Capillary-venular pressures are the upstream pressures for venous return. In exercising muscles, reduced arteriolar tone lowers arteriolar pressure and increases arterial flow. This, in turn, raises capillary-venular pressure and increases venous flow. The arteriolar-capillary waterfall is decreased or eliminated. Total blood flow is increased by diversion of blood from tissues with slow venous drainage to muscles with fast venous drainage (low resistance X compliance). The heart pumps away the increased venous return by shifting to a new ventricular function curve.
Failure of thromboxane A2 blockade to prevent attacks of vasospastic angina.
Authors: Chierchia S , de Caterina R , Crea F , Patrono C , Maseri A
Published: June 2011

Thromboxane A2 (TxA2), released by aggregating platelets, has been proposed as a potential mediator of coronary vasospasm. We studied six patients with variant angina, a clinical syndrome due to coronary vasospasm, and one patient with frequent recurrent episodes of transient ST-segment depression at rest in whom the spasm was demonstrated angiographically. All patients underwent continuous ECG monitoring for 2 days before and 2 days after a single, low, i.v. dose of aspirin (2 mg/kg), which reduced TxB2 (the stable metabolite of TxA2) to less than 3% of the control values. There were 129 transient ischemic episodes during control and 146 after aspirin, when platelet TxB2 was reduced to negligible levels. The duration, severity and incidence of symptomatic episodes were not significantly affected by TxA2 blockade. We conclude that platelet TxA2 is probably not responsible for the initiation of coronary vasospasm.
The additive antianginal action of oral nifedipine in patients receiving propranolol: magnitude and duration of effect.
Authors: Bassan M , Weiler-Ravell D , Shalev O
Published: June 2011

Ten men with stable angina not completely relieved by full doses of propranolol (mean 218 mg/day) were administered an oral dose of 10 mg of nifedipine or placebo on alternate mornings in a double-blind fashion. Patients had been trained in a protocol that precipitated angina after 3-6 minutes of bicycle exercise. On test days, with propranolol continued, bicycle exercise to angina or fatigue was performed before nifedipine or placebo administration, and hourly thereafter for 8 hours. Mean exercise duration was greater 1 hour after nifedipine than after placebo by 123 seconds (372 +/- 21 vs 249 +/- 16 seconds, p less than 0.001). By the fifth hour, the increase in exercise time was reduced to 93 seconds (p less than 0.001), and a significant, though further diminished, difference of 57 seconds was still present at 8 hours (p less than 0.01). Nifedipine lowered resting systolic blood pressure by 20 mm Hg (p less than 0.001) without appreciably changing heart rate. We conclude that nifedipine is a very effective and reasonably long-acting antianginal supplement to propranolol.
Effect of infarct location on the in-hospital prognosis of patients with first transmural myocardial infarction.
Authors: Thanavaro S , Kleiger R E , Province M A , Hubert J W , Miller J P , Krone R J , Oliver G C
Published: June 2011

We studied the in-hospital prognosis of 1105 patients who had their first transmural myocardial infarction; 611 patients (55.3%) had anterior myocardial infarction (AMI) and 494 (44.7%) had inferior myocardial infarction (IMI). Patients with IMI had a significantly lower in-hospital mortality rate (9.1% vs 15.6%, p = 0.0014) and significantly lower prevalences of congestive heart failure (39.4% vs 47.6%, p = 0.0066), cardiogenic shock ( 8.7% vs 12.6%, p = 0.0384) and conduction defects (left anterior hemiblock, right bundle branch block and intraventricular conduction defect). The patients with AMI had significantly higher peak enzyme levels, and a greater percentage of them (40.1% vs 25.9%) had SGOT greater than 240 IU/l, whereas more patients with IMI (34.6% vs 27.8%) had SGOT less than 120 IU/l (p = 0.0001). When the parallel subgroups were compared according to the peak SGOT levels (less than 120, 120-240, and greater than 240 IU/l, the differences in the mortality and morbidity between the two infarct locations diminished. However, patients with AMI still had a less favorable outcome. Logistic regression analysis demonstrated that both the peak enzyme level and the infarct location had an independent influence on the in-hospital prognosis of patients with first transmural infarction.