bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of afterload reduction on global left ventricular and regional myocardial functions in the isolated canine heart with stenosis of a coronary arterial branch.
Authors: Isoyama S , Maruyama Y , Ashikawa K , Sato S , Suzuki H , Watanabe J , Shimizu Y , Ino-Oka E , Takishima T
Published: June 2011

We examined the effects of graded reduction of afterload on the global left ventricular and regional myocardial functions as well as coronary hemodynamics in hearts with regional ischemia. We used isolated, paced canine hearts that were loaded with a hydraulic system that simulated the aortic input impedance of the dog's arterial tree. The loading conditions could be quantitatively and sequentially changed by the reduction of the systemic vascular resistance of the hydraulic system, while the preload was kept constant using a variable-height reservoir connected to the left atrium. The heart was perfused with arterial blood from a support dog. Mean coronary perfusion pressure was maintained equal to mean aortic pressure (AoP) by a servo-controlled pump. Then, the left circumflex branch was constricted to an approximate 50% flow reduction of the preischemic control condition. The myocardial lengths at ischemic and nonischemic regions were measured with two pairs of ultrasonic crystals. In the hearts without ischemia, cardiac output continued to increase, from 535 +/- 14 to 1181 +/- 74 ml/min (p less than 0.01), as mean AoP decreased fom 111 +/- 4 to 52 +/- 3 mm Hg (p less than 0.01), although mean coronary blood flow decreased by approximately 50%. During regional ischemia, at control pressures, performance of the ischemic region diminished from 0.94 +/- 0.15 to 0.77 +/- 0.15 mm (p less than 0.05). With a small decrease in afterload, from 98 +/- 6 to 86 +/- 3 mm Hg, performance improved slightly as in the normal region. With a larger reduction in afterload, from 86 +/- 3 to 55 +/- 6 mm Hg, performance of the ischemic region decreased from 0.77 +/- 0.15 to 0.61 +/- 0.15 mm (p less than 0.05) while cardiac output increased. Thus, there appears to be a bimodal change in performance: a baseline performance, perfusion pressure-mediated decrease and a second, afterload-modulated change.
Echoventriculography -- a simultaneous analysis of two-dimensional echocardiography and cineventriculography.
Authors: Erbel R , Schweizer P , Lambertz H , Henn G , Meyer J , Krebs W , Effert S
Published: June 2011

Two-dimensional echocardiography underestimates left ventricular volume compared with cineventriculography. To exclude the influence of difference in heart rate, blood pressure, respiration phases and any effect of the contrast material on left ventricular function, simultaneous studies of two-dimensional echocardiography and cineventriculography-echoventriculography were performed in 46 patients. Apical two-dimensional echocardiograms in the right anterior oblique (RAO) equivalent view were recorded before and during cineventriculography in the 30 degrees RAO projection. End-diastolic and end-systolic volumes (EDV and ESV) were calculated using a disc method with a semiautomatic computer system. The echo transducer position relative to the left ventricular apex and long axis was analyzed. For EDV determined by two-dimensional echocardiography and cineventriculography, the linear regression equation was y = 0.659x + 0.8, SEE = +/- 26.2 ml, r = 0.907. For ESV, the regression equation was y = 0.571x + 17.8, r = 0.938, SEE = +/- 18.6 ml, and for ejection fraction (EF) it was y = 0.606x + 13.0, r = 0.803, SEE = +/- 9.1%. Injection of contrast material resulted in only a small increase of stroke volume, caused by an increase of EDV as analyzed by echoventriculography. In all but two patients, the transducer position was found to be anterior and superior to the left ventricular anatomic apex, as evaluated by filming the echo transducer position during cineventriculography in 46 patients in the 30 degrees RAO projection and in 15 patients consecutively in the 60 degrees left anterior oblique and 30-40 degrees cranial projections. Thus, tangential cuts of the ventricle resulted in underestimation of diameters, long axis and ventricular volumes. These methodologic problems are exacerbated by slice-thickness artifacts. Furthermore, different outlining of left ventricular contour -- outer border of ventricular trabeculae for cine ventriculography and inner border for two-dimensional echocardiography -- seemed to result in underestimation of volume by echocardiography.
The potential impact of nuclear magnetic resonance imaging on cardiovascular diagnosis.
Authors: Kaufman L , Crooks L , Sheldon P , Hricak H , Herfkens R , Bank W
Published: June 2011

Nuclear magnetic resonance (NMR) is used to generate cross-sectional images of the human body that show excellent anatomic and functional definition. The NMR imaging process involves interactions between electromagnetic fields and the hydrogen nuclei being imaged. These interactions occur on time scales of milliseconds to seconds. Consequently, the motion of these nuclei, for instance, when carried by blood, produces distinct signatures that are used to assess flow in major vessels. Myocardial dyskinesis also produces visible effects. Because of these effects, NMR imaging may be a safe and effective tool in the diagnosis and assessment of cardiovascular disease.
The effect of variations of pulsed Doppler sampling site on calculation of cardiac output: an experimental study in open-chest dogs.
Authors: Fisher D C , Sahn D J , Friedman M J , Larson D , Valdes-Cruz L M , Horowitz S , Goldberg S J , Allen H D
Published: June 2011

We measured aortic flow by two-dimensional Doppler echocardiography in an open-chest dog model to examine how variations in Doppler sample volume length and position influence aortic hemodynamic flow calculations. Fourteen dogs underwent right-heart bypass, in which venous return from the venae cavae drained by gravity to a reservoir. A variable-speed roller pump returned the blood to the pulmonary artery, fixing left-sided cardiac input and output. Echo Doppler measurements were performed using a 3.5 MHz transducer placed directly on the aortic arch to determine internal aortic cross-sectional area. The transducer was then directed to image the aortic arch for Doppler velocity measurements and the various sampling sites were investigated. Doppler cardiac output could then be determined for each of the various sample volumes over a range of known roller pump settings. Doppler velocity was analyzed using fast Fourier transform spectral analysis. Mean velocity over the cardiac cycle was obtained by planimetry of the area under the Doppler velocity curve with a minicomputer. Doppler-derived determinations of cardiac output achieved a correlation of r = 0.98-0.99 to values obtained by the roller pump over a range of cardiac outputs from 0.75-5 l/min. The standard error of the estimate was 0.21/min. In this laminar flow model, there was no difference between the predictive accuracy of any of the sampling sites over the range of roller pump flows. Our study shows that Doppler velocity measurements can be used to quantify aortic flow over a clinically useful range and that variations of sample length and position did not produce significant differences in calculated flows.
Two-dimensional echocardiographic assessment of the idiopathic hypereosinophilic syndrome. Anatomic basis of mitral regurgitation and peripheral embolization.
Authors: Gottdiener J S , Maron B J , Schooley R T , Harley J B , Roberts W C , Fauci A S
Published: June 2011

Important cardiac manifestations in the idiopathic hypereosinophilic syndrome include mitral regurgitation and peripheral embolization. To determine the anatomic basis of these abnormalities, real-time, wide-angle, two-dimensional echocardiography (2-D echo) was performed in 21 patients with the hypereosinophilic syndrome. Nine patients (43%) had clinical evidence of mitral regurgitation, and each had localized thickening of the posterobasal left ventricular wall behind the posterior mitral leaflet and absent (seven patients) or diminished (two patients) motion of the posterior leaflet. Anatomic observations at operation or necropsy in four patients with mitral regurgitation demonstrated that the echocardiographic abnormalities resulted from posterior mitral leaflet thickening and adherence of the leaflet to the underlying mural endocardium of the posterobasal wall. On 2-D echo, each of the six patients with peripheral emboli had either apical left ventricular echo-dense targets consistent with thrombus or thickening of the posterobasal wall of the left ventricle, and these findings were validated at autopsy or operation in three patients. Hence, in patients with the hypereosinophilic syndrome, 2-D echo is useful in identifying the probable etiology of two important cardiac manifestations. Thickening of the posterobasal wall is usually associated with impairment of posterior mitral leaflet function, resulting in mitral regurgitation. Because the hypereosinophilic syndrome is associated with peripheral embolization, thrombus formation and subsequent endocardial scarring, the noninvasive identification of intracavitary ventricular thrombi may be important.
Percutaneous transluminal coronary angioplasty: report of complications from the National Heart, Lung, and Blood Institute PTCA Registry.
Authors: Dorros G , Cowley M J , Simpson J , Bentivoglio L G , Block P C , Bourassa M , Detre K , Gosselin A J , Grüntzig A R , Kelsey S F , Kent K M , Mock M B , Mullin S M , Myler R K , Passamani E R , Stertzer S H , Williams D O
Published: June 2011

The complications reported in the first 1500 patients enrolled in the National Heart, Lung, and Blood Institute Percutaneous Transluminal Coronary Angioplasty (PTCA) Registry are analyzed. Data were contributed from 73 centers between September 1977 and April 1981. PTCA was successful in 63% of attempts. Five hundred forty-three in-hospital complications occurred in 314 patients (21%). The most frequent complications were prolonged angina in 121, myocardial infarction (MI) in 72, and coronary occlusion in 70. One hundred thirty-eight patients (9.2%) had major complications (MI, emergency surgery or in-hospital death). One hundred two patients (6.8%) required emergency surgery, usually for coronary dissection or coronary occlusion. Sixteen patients (1.1%) died in-hospital; the mortality rate was 0.85% in patients with one-vessel disease and 1.9% in those with multivessel disease. The mortality rate was significantly higher in patients who had had bypass surgery (p less than 0.001). Nonfatal complications were significantly influenced by the presence of unstable angina (p less than 0.001) and initial lesion severity greater than 90% diameter stenosis (p less than 0.001). This report delineates and assesses the complications encountered with PTCA during its initial 3 1/2-year clinical experience. These results support the relative safety of PTCA as a method of nonsurgical myocardial revascularization in carefully selected patients.
Assessment of left ventricular pressure-volume relations using gated radionuclide angiography, echocardiography, and micromanometer pressure recordings. A new method for serial measurements of systolic and diastolic function in man.
Authors: Magorien D J , Shaffer P , Bush C A , Magorien R D , Kolibash A J , Leier C V , Bashore T M
Published: June 2011

This study was designed to validate the use of combined invasive and noninvasive methods in assessing serial pressure-volume relations in man. Ten patients undergoing cardiac catheterization were studied with simultaneous intracardiac micromanometer pressure recordings, gated radionuclide angiography and echocardiography. Systolic and diastolic function were measured at rest, during right atrial pacing rates of 100 and 120 beats/min and after nitroglycerin administration. Right atrial pacing studies (rate of 100 beats/min) were performed in duplicate to determine the reproducibility of the method. At the conclusion of each study, the model was validated with contrast angiography. Good reproducibility was evident when measuring the maximum and average filling and ejection rates, time to peak filling rate, ejection fraction, the modulus of chamber stiffness, the time course of left ventricular relaxation, global average stress and ventricular work indexes using the model described above. These data were not significantly different (p greater than 0.05) from comparable data obtained from contrast angiography. Right atrial pacing and nitroglycerin administration resulted in predictable alterations in the pressure-volume loop and in the systolic and diastolic measurements. The maximum and average filling rates, ejection rates and time to peak filling rate appeared to be heart rate-dependent variables. By combining available invasive and noninvasive methods, accurate pressure-volume relationships can be determined. Because the method we tested provides accurate volumetric and timing measurements for cardiac events and does not alter hemodynamics, it may be useful for obtaining serial assessments of the pressure-volume relationship in man.
Supravalvular aortic stenosis and coronary ostial stenosis in familial hypercholesterolemia: two-dimensional echocardiographic assessment.
Authors: Beppu S , Minura Y , Sakakibara H , Nagata S , Park Y D , Nambu S , Yamamoto A
Published: June 2011

The lesions of the aortic root, which are supravalvular aortic stenosis and coronary ostial stenosis, in familial hypercholesterolemia were studied using two-dimensional echocardiography. The subjects were 25 heterozygotes, six homozygotes and 30 control subjects. The internal diameters of the aortic ring, the sinus of Valsalva and the supravalvular aortic ring were measured. Measurement variation due to body size was avoided by normalizing the latter two values by the diameter of the aortic ring. Four heterozygotes and all homozygotes were judged to have stenosis of the supravalvular aortic ring; none of heterozygotes and four homozygotes had stenosis of the sinus of Valsalva. In three of the four patients with stenosis of both the supravalvular aortic ring and the sinus of Valsalva, a pressure gradient was demonstrated. The degree of supravalvular aortic stenosis correlated with the serum cholesterol level but not with patient age. All homozygotes, even very young ones, had a severe aortic root lesion. In the short-axis view of the aortic root, a lump (raised mass) on the aortic wall indicating atheromatous plaquing was demonstrated in five heterozygotes and all homozygotes. Coronary ostial stenosis was shown in three of the four patients whose plaquing echoes were adjacent to the coronary orifice. We conclude that two-dimensional echocardiography is useful in diagnosing lesions of the aortic root in patients with hypercholesterolemia.
Obesity as an independent risk factor for cardiovascular disease: a 26-year follow-up of participants in the Framingham Heart Study.
Authors: Hubert H B , Feinleib M , McNamara P M , Castelli W P
Published: June 2011

The relationship between the degree of obesity and the incidence of cardiovascular disease (CVD) was reexamined in the 5209 men and women of the original Framingham cohort. Recent observations of disease occurrence over 26 years indicate that obesity, measured by Metropolitan Relative Weight, was a significant independent predictor of CVD, particularly among women. Multiple logistic regression analyses showed that Metropolitan Relative Weight, or percentage of desirable weight, on initial examination predicted 26-year incidence of coronary disease (both angina and coronary disease other than angina), coronary death and congestive heart failure in men independent of age, cholesterol, systolic blood pressure, cigarettes, left ventricular hypertrophy and glucose intolerance. Relative weight in women was also positively and independently associated with coronary disease, stroke, congestive failure, and coronary and CVD death. These data further show that weight gain after the young adult years conveyed an increased risk of CVD in both sexes that could not be attributed either to the initial weight or the levels of the risk factors that may have resulted from weight gain. Intervention in obesity, in addition to the well established risk factors, appears to be an advisable goal in the primary prevention of CVD.
Persistent sinus nodal electrograms during abnormally prolonged postpacing atrial pauses in sick sinus syndrome in humans: sinoatrial block vs overdrive suppression.
Authors: Asseman P , Berzin B , Desry D , Vilarem D , Durand P , Delmotte C , Sarkis E H , Lekieffre J , Thery C
Published: June 2011

A transvenous electrode catheter technique was used for direct recording of bipolar sinus node electrograms during postpacing atrial pauses. Multiple repetitive local sinus node electrograms during atrial quiescence validate sinus node electrograms. Such atrial pauses with sinus node electrograms are due to sinoatrial block; atrial pauses without sinus node electrograms are due to overdrive suppression or improper recording. Eight consecutive patients were prospectively selected on the basis of a corrected sinus node recovery time greater than 1500 msec during diagnostic electrophysiologic evaluation. Six patients had atrial pauses with sinus node electrograms; three patterns of sinus node electrograms during atrial pauses were observed. We conclude that (1) sinus node electrogram recording is of value in understanding the mechanism underlying postpacing atrial pauses; (2) atrial pauses are usually (6/8) caused by sinoatrial block; (3) three patterns of sinus node electrograms are observed, thus making indirect interpretation unreliable.
Electrocardiographic changes after streptokinase-induced recanalization in patients with acute left anterior descending artery obstruction.
Authors: Blanke H , Scherff F , Karsch K R , Levine R A , Smith H , Rentrop P
Published: June 2011

ECG changes were assessed in 15 patients in whom intracoronary streptokinase recanalized a totally occluded left anterior descending artery during acute myocardial infarction. These results were compared retrospectively with those in 22 comparable conventionally treated patients who underwent catheterization during the acute stage of infarction. Before angiography no significant differences were found in the sum of ST elevation (sigma ST increase V1-V6), the sum of R waves (sigma RV1-V6), or the number of Q waves (nQV1-V6) in leads V1 through V6. sigma ST increase V1-V6 was significantly lower in the streptokinase group than in control patients at all times after angiography. sigma RV1-V6 declined and nQV1-V6 increased in both groups during the first 12 hr, but there was no further change in the control group, whereas in the streptokinase group a significant increase in sigma RV1-V6 and decrease in nQV1-V6 followed. There was a significant correlation between long-term electrocardiographic (sigma RV1-V6; nQV1-V6) and angiographic findings (ejection fraction, akinetic segment length). Thus, the Q wave regression and increase in sigma RV1-V6 after streptokinase suggest, in accordance with angiographic findings, that jeopardized myocardium was salvaged by reperfusion.
Quantitative assessment of myocardial ischemia and necrosis by continuous vectorcardiography and measurement of creatine kinase release in patients.
Authors: Sederholm M , Grøttum P , Erhardt L , Kjekshus J
Published: June 2011

The accuracy of the use of the maximal QRS vector difference to estimate myocardial infarct size irrespective of infarct location was compared with that of measurement of cumulative creatine kinase (CK) release. Sixty patients with acute myocardial infarction and a history of symptoms of less than 4 hr duration were followed for 24 to 72 hr with orthogonal vectorcardiography and CK release analysis. Spatial QRS vector differences were calculated between the first QRS complex recorded and subsequent QRS complexes at timed intervals. The QRS vector difference increased rapidly and reached a plateau at an average 12.1 hr after onset of symptoms, as compared with 34.0 hr for the cumulated CK release. In 42% of the patients a stepwise progression of infarct evolution was observed. Irrespective of infarct location the maximal spatial ST vector magnitude was related to the ultimate QRS vector difference (r = .80) and to the cumulative amount of CK released (r = .64). Furthermore, maximal QRS vector difference correlated well with the maximal cumulative CK release (r = .64) Ten patients had possible infarct expansion, as indicated by recurrent QRS changes without concomitant CK release. Fifteen patients had infarct extension that was indicated by secondary CK release and that in seven patients was associated with further QRS changes. Infarct extension caused an approximate 25% increase in infarct size. Spatial ST vector magnitude, QRS vector difference, and cumulative CK release are complementary measures in the quantification of evolving myocardial injury after acute coronary occlusion and in the determination of sequels to therapeutic interventions.
Right ventricular tachycardia: clinical and electrophysiologic characteristics.
Authors: Buxton A E , Waxman H L , Marchlinski F E , Simson M B , Cassidy D , Josephson M E
Published: June 2011

This report describes the clinical and electrophysiologic characteristics of 30 patients without myocardial disease who had ventricular tachycardia with the morphologic characteristics of left bundle branch block and inferior axis. The tachycardias were nonsustained in 24 patients, sustained (greater than 30 sec) in six patients, and provocable by exercise in 14 of 23 patients undergoing a standard Bruce protocol. Ventricular tachycardia was induced during electrophysiologic study in 22 of 30 patients. Programmed stimulation induced tachycardia in 10 of 30 patients, most frequently by rapid atrial or ventricular pacing. Isoproterenol infusion facilitated tachycardia induction in 13 of 23 patients. Endocardial activation mapping, performed in 10 patients, confirmed that earliest ventricular activation during tachycardia occurred at the right ventricular outflow tract on the interventricular septum. These tachycardias were unique in their responsiveness to a wide variety of antiarrhythmic drugs, including type I drugs and propranolol. During a mean follow-up of 30 months, no patient has died or experienced cardiac arrest. Two patients appear to be in spontaneous remission, and no patient has developed additional signs of cardiac disease.
Fifteen year survival study of patients with obstructive coronary artery disease.
Authors: Proudfit W J , Bruschke A V , MacMillan J P , Williams G W , Sones F M
Published: June 2011

Survival rates were determined for a group of 598 patients in whom severe coronary disease was demonstrated by arteriography; initially they were treated medically and were followed-up for 15 years. Deaths due to noncoronary causes were uncommon (5% of total) in the first 5 year period but were frequent (36%) in the third period. Survival rates were 48%, 28%, 18%, and 9% for patients with single-, double-, triple-, and left main artery disease, respectively. Abnormalities documented by ventriculography were related to survival. In 386 patients who would have been candidates for bypass surgery, survival rates were 58%, 35%, 26%, and 11% for those with single-, double-, triple-, and left main artery disease, respectively. Cardiac survival curves for single-, double-, and triple-artery disease in candidates for surgery and curves constructed on the basis of 3% mortality per artery per year corresponded fairly closely. When an abnormal electrocardiogram (ECG) is considered as a single variable in multivariate analysis, 5 year survival rates of candidates for surgery were influenced by the following in order of importance: abnormal ECG, symptoms at least 5 years in duration, triple-artery disease, double-artery disease, and arteriosclerosis obliterans. A simple prognostic stratification was devised that used only ECGs and duration of symptoms for each subset based on the number of arteries affected.
Bayesian probability analysis: a prospective demonstration of its clinical utility in diagnosing coronary disease.
Authors: Detrano R , Yiannikas J , Salcedo E E , Rincon G , Go R T , Williams G , Leatherman J
Published: June 2011

One hundred fifty-four patients referred for coronary arteriography were prospectively studied with stress electrocardiography, stress thallium scintigraphy, cine fluoroscopy (for coronary calcifications), and coronary angiography. Pretest probabilities of coronary disease were determined based on age, sex, and type of chest pain. These and pooled literature values for the conditional probabilities of test results based on disease state were used in Bayes' theorem to calculate posttest probabilities of disease. The results of the three noninvasive tests were compared for statistical independence, a necessary condition for their simultaneous use in Bayes' theorem. The test results were found to demonstrate pairwise independence in patients with and those without disease. Some dependencies that were observed between the test results and the clinical variables of age and sex were not sufficient to invalidate application of the theorem. Sixty-eight of the study patients had at least one major coronary artery obstruction of greater than 50%. When these patients were divided into low-, intermediate-, and high-probability subgroups according to their pretest probabilities, noninvasive test results analyzed by Bayesian probability analysis appropriately advanced 17 of them by at least one probability subgroup while only seven were moved backward. Of the 76 patients without disease, 34 were appropriately moved into a lower probability subgroup while 10 were incorrectly moved up. We conclude that posttest probabilities calculated from Bayes' theorem more accurately classified patients with and without disease than did pretest probabilities, thus demonstrating the utility of the theorem in this application.
Work capacity and left ventricular function during rehabilitation after myocardial revascularization surgery.
Authors: Foster C , Pollock M L , Anholm J D , Squires R W , Ward A , Dymond D S , Rod J L , Saichek R P , Schmidt D H
Published: June 2011

A prospective randomized trial was conducted to evaluate the effects of exercise-based cardiac rehabilitation after myocardial revascularization surgery (MRS) on work capacity (measured in mets) and left ventricular function as determined from ejection fraction (LVEF). Twenty-eight patients undergoing MRS were randomly assigned to experimental (aerobic exercise, n = 19) or control (muscle relaxation and low-level exercise, n = 9) groups. Patients were studied before surgery (T1) and 2 (T2), 8 (T3), and 24 (T4) weeks after surgery with first-pass radionuclide angiography both while they were at rest and during maximal upright cycle ergometric exercise. Subsets of patients were also studied at T2, T3, and T4 at a standard workload of 75 W, and during maximal exercise 1 year after surgery (T5). Work capacity improved in both groups although significantly more so in the experimental group (3.9, 3.8, 6.0, and 7.3 mets and 3.7, 3.7, 4.9, and 5.7 mets at T1, T2, T3, and T4 in the experimental and control groups, respectively). The differences between groups were significant by T3. Peak exercise LVEF increased significantly in both groups from T1 to T2 then decreased at T3 and remained unchanged through T5. Peak exercise LVEF at T3 to T5 remained significantly above that observed at T1. LVEF responses were not related to the exercise program. During a standard workload, heart rate decreased, blood pressure increased, and LVEF did not change in either group. After conclusion of the formal protocol (T4), work capacity and LVEF did not change for either group throughout an additional 6 months (T5).(ABSTRACT TRUNCATED AT 250 WORDS)
Effect of propranolol in postinfarction patients with mechanical or electrical complications.
Authors: Furberg C D , Hawkins C M , Lichstein E
Published: June 2011

In "post hoc" subgroup analyses, a simple classification system for patients, based on the presence or absence of findings indicative of electrical and/or mechanical complications early during short-term hospitalization, was applied to the data from the Beta-Blocker Heart Attack Trial (BHAT). In the largest subgroup of BHAT patients who had no reported complications, the 25 month mortality was low and the observed benefit of propranolol therapy small. Patients with electrical complications only had intermediate mortality and a pronounced effect of treatment was observed. Those with mechanical complications had the highest mortality and experienced an intermediate relative benefit of beta-blocker treatment. They also reported the most adverse effects. Post hoc analyses should always be interpreted cautiously. It is important to determine whether these findings are present in other completed beta-blocker trials. On the basis of these analyses alone it is suggested that the present practice of prescribing beta-blockers in postinfarction patients should not be altered.
Hemorrhage and the products of fibrinogen digestion after intracoronary administration of streptokinase.
Authors: Timmis G C , Gangadharan V , Ramos R G , Hauser A M , Westveer D C , Stewart J , Goodfliesh R , Gordon S
Published: June 2011

Hemorrhage was prospectively identified in 26 of 116 consecutive patients (23%) who were receiving intracoronary streptokinase for occlusive coronary thrombi producing infarction. Bleeding was not influenced by the dose of streptokinase or the method of cardiac catheterization. Before treatment, prothrombin time and partial thromboplastin time were normal in both bleeders and nonbleeders. Fibrinogen levels measured by bioassay after streptokinase (mean +/- SEM) were 62 +/- 29 mg/dl in patients with major bleeding, 111 +/- 26 mg/dl in patients with minor bleeding, and 109 +/- 13 mg/dl in nonbleeders (p = NS). The regression slope b calculated from poststreptokinase fibrinogen time-concentration data in 71 patients was 4.7 mg/dl/hr. However, mean fibrinogen concentrations calculated at sequential 5 hr intervals revealed no net regeneration for the first 20 hr after thrombolysis. The apparent fibrinogen regeneration rate was less than normal (31 mg/kg/day) for more than 10 hr but subsequently increased to 94 +/- 10 mg/kg/day by the second day. The initial apparent latency of fibrinogen regeneration paralleled the sharp rise in fibrinogen degradation products, which began to decline after 20 hr of treatment but remained elevated well into the second day. Because of their anticoagulant effects, these products may interfere with the fibrinogen assay, causing spuriously low results. Thus, whether the early delay in fibrinogen regeneration is real or simply a reflection of the effects of fibrinogen degradation products on the bioassay, it signals the time for caution in initiating systemic heparin therapy.
The spontaneous occurrence of paroxysmal supraventricular tachycardia.
Authors: Pritchett E L , Smith M S , McCarthy E A , Lee K L
Published: June 2011

The seemingly unpredictable occurrence of paroxysmal supraventricular tachycardia has impeded understanding of its clinical course. We documented recurring tachycardia by telephone transmission of the electrocardiogram in 14 patients and measured the "tachycardia-free periods" between the start of therapy and the first recurrence of tachycardia and between successive recurrences. We showed that attacks of tachycardia were clinically independent by calculating the autocorrelation function for 12 to 14 consecutive tachycardia-free periods. We also found that the periods between attacks closely fit an exponential probability distribution, indicating that the occurrence of tachycardia in time was a type of random event called a Poisson process. Furthermore, occurrence of tachycardia was uniformly distributed throughout a dosing interval; there was no predilection for tachycardia to occur late in a dosing interval when plasma drug levels were presumed to be lowest. Measuring the tachycardia-free period is a simple and useful method for objectively studying paroxysmal supraventricular tachycardia and may be applied to the study of other paroxysmal arrhythmias.
Two-dimensional echocardiographic assessment of the aorta in infants and children with congenital heart disease.
Authors: Huhta J C , Gutgesell H P , Latson L A , Huffines F D
Published: June 2011

To determine the accuracy of two-dimensional echocardiography in the identification of congenital anomalies of the aorta, we compared two-dimensional echocardiographic with angiographic results in 261 consecutive infants and children with congenital heart disease (age 1 day to 20 years, mean 3.3 years). Two-dimensional echocardiography was performed and interpreted without knowledge of angiographic results. Complete visualization of the ascending and descending aorta and aortic arch branches was possible by two-dimensional echocardiographic examination in suprasternal, parasternal, and subcostal views of 255 patients (98%). Identification of the esophagus during swallowing aided the diagnosis of anatomic characteristics of aortic arch. One or more significant aortic arch anomalies were present on angiograms of 116 of 255 patients (46%) and were detected by two-dimensional echocardiography in 110 (sensitivity 95%, 99% specificity). Anomalies detected by two-dimensional echocardiography/angiography were ascending aorta hypoplasia in four/four, truncus arteriosus three/three, right aortic arch 31/31, anomalous subclavian artery 11/16, coarctation 27/29, and patent ductus arteriosus 53/57. We conclude that two-dimensional echocardiography can be used to determine the anatomy of the aorta in most infants and children. In selected patients, two-dimensional echocardiography may eliminate the need for angiographic examination before surgery for congenital heart disease.
Embolic potential of left ventricular thrombi detected by two-dimensional echocardiography.
Authors: Haugland J M , Asinger R W , Mikell F L , Elsperger J , Hodges M
Published: June 2011

We sought to determine whether an association existed between the echocardiographic appearance of left ventricular thrombi and systemic embolization. We reviewed the clinical and echocardiographic characteristics of 60 patients who underwent diagnostic two-dimensional echocardiography for left ventricular thrombi. Sixteen of these 60 patients (27%) had evidence of systemic embolization. Multiple echocardiographic characteristics of left ventricular thrombi were analyzed, including mobility, shape, heterogeneity, echo density, layering, central echo lucency, presence within an aneurysm, and association with low-density swirling echoes. Incidence of embolization was significantly higher in patients with thrombi that were mobile or protruded into the left ventricular cavity (p less than .002 and p less than .05, respectively). Bayesian analysis indicated that the pretest likelihood for embolization was 27% and increased in the presence of mobility, central echo lucency, and protrusion to 60%, 50%, and 40%, respectively. A stepwise regression indicated that mobility was the first and protrusion the second most helpful echocardiographic characteristic in identifying patients with embolic phenomena. Clinical features were of less help in identifying the risk for embolization of patients with left ventricular thrombi. Nine of 31 patients (29%) with recent myocardial infarction (less than 3 weeks) has emboli in contrast to five of 26 patients (19%) with remote myocardial infarction (greater than 3 weeks) (p = NS). The three patients without infarction had congestive cardiomyopathy and two had emboli.
Home versus group exercise training for increasing functional capacity after myocardial infarction.
Authors: Miller N H , Haskell W L , Berra K , DeBusk R F
Published: June 2011

To evaluate the efficacy of exercise training for increasing functional capacity in the 6 months after clinically uncomplicated myocardial infarction, 198 men 52 +/- 9 years of age participated in a training study. They were randomly assigned to one of four exercise protocols: 8 to 26 weeks of training at home (group 1, n = 66) or in a group program (group 2, n = 61) following treadmill testing performed 3 weeks after infarction, treadmill testing at 3 weeks without subsequent training (group 3, n = 34), and treadmill testing for the first time at 26 weeks (control, n = 37). At 26 weeks functional capacity was significantly higher in patients training at home or in a group program than that in patients without training or in control patients: 8.1 +/- 1.5, 8.5 +/- 1.3, 7.5 +/- 1.8, and 7.0 +/- 1.7 METs, respectively (p less than .05 and p less than .001). No significant differences in functional capacity were noted between patients training at home and those in a group program. No training-related complications occurred. Home and group training are equally effective in increasing functional capacity of low-risk patients after myocardial infarction.
Incidence of the coexistence of left ventricular false tendons and premature ventricular contractions in apparently healthy subjects.
Authors: Suwa M , Hirota Y , Nagao H , Kino M , Kawamura K
Published: June 2011

The incidence of the coexistence of left ventricular false tendons and premature ventricular contractions (PVCs) was evaluated prospectively. Over 14 months, left ventricular false tendons were found in 71 (6.4%) of 1117 consecutive patients examined echocardiographically. Two types of false tendons were observed: longitudinal, from the ventricular septum to the posteroapical wall (n = 62), and transverse, between the septum and the lateral wall (n = 9). Among 62 patients with PVCs and no underlying heart disease, false tendons were detected in 35 (56%); 28 had unifocal and seven had bifocal PVCs. Episodes of ventricular tachycardia were documented in one of the 28 patients with unifocal PVCs and in one of the seven patients with bifocal PVCs. These PVCs were poorly controlled by antiarrhythmic drugs but easily suppressed by exercise. Left ventricular false tendons were detected in 36 patients on routine echocardiographic examinations performed in the other 1055 subjects, and 10 of these patients were judged to have no underlying heart disease. PVCs were detected in two (20%) of these 10 patients. Although a definite conclusion that left ventricular false tendons are arrhythmogenic cannot be derived from these results, the unexpectedly high incidence of the coexistence suggests that left ventricular false tendons may be an etiologic factor in the development of PVCs, especially the rate-dependent and medically uncontrollable PVCs seen in apparently healthy individuals.
Dynamic mechanisms in human coronary stenosis.
Authors: Brown B G , Bolson E L , Dodge H T
Published: June 2011

At the clinical level, coronary stenoses frequently behave as though the obstruction to flow were variable and not as rigidly fixed as previously imagined. Pressure (energy) lost in flow through a stenosis is the primary determinant of its hemodynamic impact. Ischemic episodes occur when pressure distal to the stenosis falls below that needed to perfuse the subendocardium. Three important properties of the stenosis contribute to variation in its pressure loss. First, loss is proportional to the square of stenosis flow. Thus proper distribution of perfusion is doubly vulnerable to conditions such as exercise, anemia, or pharmacologic vasodilation, which ordinarily increase myocardial blood flow. Second, pressure loss is proportional to the inverse fourth power of minimum lumen diameter. As a result, seemingly small changes in diameter are amplified to large changes in stenosis resistance. Third, a compliant arc of normal arterial wall borders part of the lumen in the majority of coronary lesions. This extremely important morphologic feature of stenoses permits transient variation in stenosis lumen diameter in response to drugs or to variation in endogenous vasomotor activity or intraluminal pressure. Although our understanding is incomplete, many of the clinical features of coronary disease and its pharmacologic responses are explained in terms of these stenosis properties and their interaction.
Right ventricular and right atrial collapse in patients with cardiac tamponade--a combined echocardiographic and hemodynamic study.
Authors: Singh S , Wann L S , Schuchard G H , Klopfenstein H S , Leimgruber P P , Keelan M H , Brooks H L
Published: June 2011

To determine the hemodynamic derangement associated with right ventricular diastolic collapse and to assess the value of right ventricular and right atrial collapse in identifying cardiac tamponade, two-dimensional echocardiograms were recorded simultaneously with measurement of right atrial, pulmonary capillary wedge, intrapericardial, and systemic arterial pressures and cardiac output in 16 patients as they underwent pericardiocentesis. Twelve patients (group I) had evidence of right ventricular or right atrial collapse or both on their echocardiograms and hemodynamic evidence of cardiac tamponade before pericardiocentesis. All hemodynamic parameters improved after pericardiocentesis (p less than or equal to .05). Continuous monitoring during pericardiocentesis in three of these patients showed significant improvement in all parameters except heart rate (p less than or equal to .02) at the point of disappearance of right ventricular diastolic collapse, with further improvement in cardiac output as pericardiocentesis continued (p less than .01). Right atrial collapse persisted after right ventricular collapse disappeared but was no longer present when pericardiocentesis was completed. Three patients (group II) had no right ventricular or right atrial collapse, no hemodynamic evidence of cardiac tamponade, and no improvement in hemodynamic parameters after pericardiocentesis. A single patient (group III) was found to have elevated right heart pressures and right ventricular hypertrophy before pericardiocentesis. Although there was hemodynamic evidence of cardiac tamponade in this patient, there was no evidence of right ventricular or right atrial collapse. In this study, the sensitivity of right ventricular collapse as a marker for cardiac tamponade was 92%, its specificity 100%, its accuracy 94%, and its predictive value 100%.(ABSTRACT TRUNCATED AT 250 WORDS)
Evaluation of relationship between myocardial contractile state and left ventricular function in patients with aortic regurgitation.
Authors: Shen W F , Roubin G S , Choong C Y , Hutton B F , Harris P J , Fletcher P J , Kelly D T
Published: June 2011

We studied the relationship between myocardial contractile state and left ventricular functional response to exercise in 14 asymptomatic patients with isolated moderate-to-severe aortic regurgitation and six control subjects. The slope of the systolic blood pressure-left ventricular end-systolic volume (pressure-volume) relationship determined by radionuclide ventriculography during angiotensin infusion was used as an indirect measure of myocardial contractility and was compared with left ventricular ejection fraction at rest and during both isometric handgrip and dynamic bicycle exercise. The slope of the pressure-volume relationship was significantly lower in patients with aortic regurgitation than in the control subjects (1.75 +/- 0.57 vs 2.78 +/- 0.42, p less than 0.01). The slope correlated exponentially with resting ejection fraction and was linearly related to changes in left ventricular ejection fraction during both handgrip and bicycle exercise. In patients with aortic regurgitation, resting ejection fraction may overestimate myocardial function. The slope of the pressure-volume relationship measured during afterload stress and left ventricular ejection fraction response to exercise intervention more reliably reflect the degree of left ventricular dysfunction.
Morphologic changes in the pulmonary arteries after percutaneous balloon angioplasty for pulmonary arterial stenosis.
Authors: Edwards B S , Lucas R V , Lock J E , Edwards J E
Published: June 2011

The pathologic appearance of pulmonary arteries subjected to balloon dilation was studied in four subjects with stenosis of pulmonary arteries. Nine vessels were dilated. Successful dilation in seven vessels was accompanied by intimal disruption and tearing of the media. In one vessel, at the site of a previous surgical procedure, dilation could not be accomplished. Histologically, this vessel was encased by reactive fibrous tissue, which may have precluded successful dilation. In one case, simultaneous rupture of the dilating balloon and the left pulmonary artery occurred. Morphologic examination could not adequately explain the cause of vessel rupture. Among the six vessels successfully dilated and studied 4 to 14 months after the dilation, the postdilation luminal diamter had been maintained. Tears in the intima and media as seen histologically had been filled in by scar tissue. In one artery a dilated segment distal to a residual obstruction revealed marked intimal proliferation.
Association between the exercise ejection fraction response and systolic wall stress in patients with chronic aortic insufficiency.
Authors: Greenberg B , Massie B , Thomas D , Bristow J D , Cheitlin M , Broudy D , Szlachcic J , Krishnamurthy G
Published: June 2011

We studied the exercise ejection fraction response in 56 patients with chronic aortic insufficiency. All had left ventricular dilatation but preserved resting ejection fraction and minimal or no symptoms. The exercise ejection fraction increased by 0.05 units or greater in 18 (32%) patients (group I), remained within 0.05 units of the resting value in 18 (32%) patients (group II), and fell by 0.05 units or greater in 20 (36%) patients (group III). There were no significant differences among the groups in left ventricular end-diastolic dimension, end-systolic dimension, or fractional shortening by echocardiography or in resting left ventricular volumes and ejection fraction by radionuclide angiography. Left ventricular end-systolic wall stress was significantly higher in group III than in either group I or group II (89 +/- 20 vs 70 +/- 18 and 69 +/- 17 X 10(3) dyne/cm2; p less than .005). At peak exercise there were no differences among groups in systolic blood pressure. However, end-systolic volume increased from 65 +/- 28 to 77 +/- 36 ml/m2 in group III and fell from 50 +/- 21 to 28 +/- 18 ml/m2 in group I during exercise. Thus, at peak exercise end-systolic volume was nearly three times greater in group III than in group I. Although stress could not be determined directly during exercise, the directional changes in its determinants suggest that it also would have been higher in group III patients. A highly significant inverse correlation was present between the ejection fraction response and the change in end-systolic volume (r = -.87, p less than .0001).(ABSTRACT TRUNCATED AT 250 WORDS)
Flow velocity patterns in and distensibility of the carotid artery bulb in subjects of various ages.
Authors: Reneman R S , van Merode T , Hick P , Hoeks A P
Published: June 2011

Velocity patterns in and distensibility of the carotid artery bulb were studied in younger (20 to 30 years; n = 11) and older (50 to 60 years; n = 9) volunteers without detectable lesions of the cervical carotid arteries by means of a high-resolution, multigate, pulsed Doppler system coupled to a B mode imager. In the bulb the axial velocities were highest on the side of the flow divider, while regions of flow separation and recirculation were observed on the side opposite to this divider. Flow separation and recirculation were less pronounced and less common in the older subjects. Flow separation was not continuously present throughout the cardiac cycle. The distensibility of the carotid arteries was significantly diminished in older subjects, especially in the bulb. The velocity patterns in the carotid artery bulb of younger subjects corroborate the patterns observed in models. The diminished flow separation and recirculation in the older subjects might result from alterations in distensibility at the transition from common to internal carotid artery with increasing age.