bluuebunny/crossref_metadata_2025 huggingface dataset:
Dual radionuclide study of myocardial infarction. Relationships between myocardial uptake of potassium-43, technetium-99m stannous pyrophosphate, regional myocardial blood flow and creatine phosphokinase depletion.
Authors: Zaret B , DiCola V C , Donabedian R K , Puri S , Wolfson S , Freedman G S , Cohen L S
Published: June 2012

The dual radionuclide myocardial distributions of imaging agents potassium-43 (43K) and technetium-99m stannous pyrophosphate (99mTc-PYP) were studied in a 24-hour closed chest canine infarct preparation. In multiple myocardial biopsies in 20 dogs, tissue levels of both radionuclides were compared to either an index of tissue viability (myocardial creatine phosphokinase [CPK] depletion), or to estimates of regional myocardial blood flow as measured by the microsphere technique. Myocardial 43K uptake in the ischemic and infarcted zone correlated well with both CPK depletion (r = 0.73) and microsphere estimates of relative blood flow. The correlation with microspheres was excellent in the transmural sample (r = 0.93) as well as endocardial (r = 0.97) and epicardial (r = 0.86) portions. On the other hand, 99mTc-PYP myocardial uptake did not correlate with the extent of CPK depletion. Maximal uptake was frequently noted in border zones with only moderate CPK depletion, while lesser degrees of 99mTc-PYP uptake were noted in the central infarct zone where CPK activity was lowest. The relationship of 99mTc-PYP uptake to microsphere regional flow estimates demonstrated that 99mTc-PYP uptake was maximal at flows of 0.3 to 0.4 of normal. At lower flows, 99mTc-PYP uptake fell toward normal levels. A similar relationship was noted between the distributions of 99mTc-PYP and 43K. In relatively high flow border segments (larger than or equal to 0.80 of normal), abnormal 99mTc-PYP uptake of five to six times normal persisted. The transmural distribution of 99mTc-PYP demonstrated that in low flow regions 99mTc-PYP uptake was primarily epicardial, while in the higher flow ischemic periphery of the infarct endocardial uptake predominated. Thus, while there is a direct correlation between cationic 43K myocardial uptake and regional myocardial viability and blood flow, no such direct relationship exists for 99mTc-PYP. This is in part based on the necessity for delivery of the radioactive tracer to the infarct zone.
Left ventricular end-diastolic pressure volume relationships with experimental acute global ischemia.
Authors: Palacios I , Johnson R A , Newell J B , Powell W J
Published: June 2012

The mechanism of elevation of left ventricular end-diastolic pressure during acute global ischemia was evaluated by examiniation of the relative contributions of a decrease in contractility and an alteration of the pressure-volume relationship. The external circumference (mercury-in-silastic gauge) pressure relationship, as an index of the pressure-volume relationship, was studied in beta adrenergic and ganglionic blocked, open chest dogs on right heart bypass at constant heart rate ane aortic pressure. Ischemia of one and two hours' duration was produced by reducing total coronary blood flow in cannulated left and right coronary arteries until left ventricular end-diastolic pressure rose significantly. At a constant stroke work, left ventricular end-diastolic pressure rose from 5.0 +/- 0.5 to 15.0 +/- 0.5 cm H2O in the experiments of one hour of ischemia, and from 7.0 +/- 1.0 to 17.0 +/- 1.0 cm H2O in experiments of two hours of ischemia. Ischemia was followed by one hour of restoration of coronary blood flow. Ischemia produced a marked depression of ventricular function: stroke work, considered at a left ventricular end-diastolic pressure of 15 cm H2O, decreased from 21.0 +/- 3.0 to 3.5 +/- 0.5 gm-m, and from 15.0 +/- 2.0 to 2.5 +/- 0.5 gm-m, in the experiments of one and two hours, respectively. Neither ischemia nor reflow changed the pressure-volume relationship. Thus, the elevation of left ventricular end-diastolic pressure during ischemia in an otherwise normal canine myocardium is due to a decrease in systolic performance of the heart rather than to an alteration of the pressure-volume relationship.
Asymptotic slope of log pressure vs log volume as an approximate index of the diastolic elastic properties of the myocardium in man.
Authors: Laird J D
Published: June 2012

The goal of this study was to develop, on a rational basis, an index of the intrinsic diastolic elastic properties of the left ventricle. A relatively simple analytic model employing a thin-walled spherical geometry coupled with an approximate formulation of a two-dimensional constitutive relation, was used to examine the primary determinants of the pressure-volume relationship of the intact heart. The results permit comparison with other indices of compliance or wall stiffness. The slope of the dP/dV vs P curve was found to be sensitive to the non-linear elastic constant K, but is also sensitive to variations in cardiac muscle volume. VdP/dV was found to be sensitive to pressure. m = d(log P)/d(log V) = (V/P)(dP/dV) is proposed as an index sensitive to K and relatively insensitive to both pressure and initial cardiac geometry. The index is compared with published studies. Using the data of Fester and Samet, mean values of the asymptotic log-log P-V slope, m, evaluated at end-diastole for normal, idiopathic hypertrophy, mild, moderate and severe coronary artery disease were 3.95 +/- 0.60 (SEM), 5.05 +/- 1.60, 5.24 +/- 0.96, 8.35 +/- 2.06, and 15.13 +/- 3.0, respectively. At values of LVEDP less than 7 mm Hg the concept of simple distension is questioned. The advantages and limitations of this approximate index are discussed. This index seems to afford a practical measure of the elastic properties of the wall over a rather wide range of pressure, volume, wall mass and wall thickness.
Myocardial lesions of progressive systemic sclerosis. A cause of cardiac dysfunction.
Authors: Bulkley B H , Ridolfi R L , Salyer W R , Hutchins G M
Published: June 2012

The nature, prevalence, functional significance, and indeed existence of myocardial disease in progressive systemic sclerosis (PSS) has been debated. In this study the clinical and pathological features of 52 autopsied patients were analyzed in an attempt to resolve these questions. A distinctive focal myocardial lesion ranging from contraction band necrosis to replacement fibrosis throughout both ventricular walls was present in 23 patients who had widely patent extramural coronary arteries. There were no morphologic abnormalities of the intramyocardial coronary arteries to account for these lesions. Comparing those patients having severe (13), mild (10), or no (24) PSS myocardial lesions, and patent extramural coronary arteries, there were no major differences in age, sex, frequency and severity of pulmonary, renal or hypertensive disease which could account for the myocardial necrosis and fibrosis. The three groups did differ, however, with regard to clinical cardiac abnormalities: ventricular arrhythmias and conduction disturbances were six and two times as frequent, respectively, in those with severe myocardial PSS compared to the other two groups. A pattern of primary myocardial disease with intractable congestive heart failure resulted from severe myocardial PSS in four patients, angina pectoris with normal coronary arteries was associated with the severe myocardial lesion in three patients, and sudden death in five. The occurrence of contraction band necrosis suggests that the myocardial damage in PSS might be due to intermittent vascular spasm of the type recognized in the digits and possibly kidneys and lungs, i.e., an intramyocardial Raynaud's phenomenon. The findings in our patients clearly show that myocardial progressive systemic sclerosis is a distinct entity with relatively frequent occurrence which may lead to arrhythmias, congestive heart failure, angina pectoris with normal coronary arteries and sudden death.
Effects of p-chlorophenoxyisobutyrate on myocardial free fatty acid extraction, ventricular blood flow, and epicardial ST-segment elevation during coronary occlusion in dogs.
Authors: Mjos O D , Miller N E , Riemersma R A , Oliver M F
Published: June 2012

The effect of p-chlorophenoxyisobutyrate (CPIB) on ST-segment elevation in epicardial electrocardiographic recordings was studied during coronary artery occlusion in dogs. Occlusion alone raised the sum of ST-segment elevations (sigmaST) to 26 +/- 6 mV (mean +/- SEM). Intravenous (i.v.) administration of CPIB 30 min before re-occlusion reduced sigmaST to 14 +/- 3 mV (P less than 0.03). A continuous i.v. infusion of isoproterenol increased sigmaST to 74 +/- 11 mV. Pretreatment with CPIB reduced sigmaST during isoproterenol infusion to 40 +/- 7 mV (P less than 0.005). CPIB had no effect on mean aortic blood pressure, heart rate, or regional myocardial blood flow, as measured by radioactive microspheres. Arterial free fatty acid (FFA) concentrations were reduced by CPIB from 466 +/- 41 to 221 +/- 44 muEq/L (P less than 0.001) in the basal state, and from 1966 +/- 183 to 1429 +/- 209 muEq/L (P less than 0.001) during isoproterenol infusion. The reduction in arterial FFA concentration was associated with a proportionate decrease in the myocardial extraction of FFA. Similar changes were observed when CPIB was administered during an occlusion which had been established 10 min earlier. These observations support other evidence that the severity of acute myocardial ischemic injury in dogs is positively correlated with the myocardial extraction of FFA, and that the severity of the ischemic injury can be reduced by effective antilipolytic therapy.
N-dimethylisopropyl propranolol. Effects on myocardial oxygen demands.
Authors: Olson E G , Goodyer A V , Langou R A , Cohen L S , Wolfson S
Published: June 2012

N-Dimethylisopropyl propranolol (DMP) is a quaternary derivative which lacks significant beta-adrenergic blocking and local anesthetic effects. It has been reported, nonetheless, to be effective in treating experimental arrhythmias and in limiting the extent of ST-segment elevations following experimental coronary occlusion. The present study examined the effects of DMP on the hemodynamics and myocardial oxygen demands of anesthetized dogs. After a single dose of 3 mg/kg, heart rate fell from 146 +/- 8 to 124 +/- 6 beats/min (P less than 0.0025), and aortic systolic pressure fell from 151 +/- 11 to 141 +/- 9 mm Hg (0.05 less than P less than 0.10), resulting in a 16.8% reduction in the tension-time index. Stroke volume was reduced by 10% despite a 54% increase in left ventricular end-diastolic pressure, suggesting a negative inotropic effect. This was supported by a decrease in maximum extrapolated contractile element velocity from 9.10 +/- 1.05 to 6.61 +/- 65 units/sec (P less than 0.0025). Myocardial oxygen consumption was reduced from 12.0 +/- 1.4 to 9.9 +/- 1.5 ml/min/100 g tissue (P less than 0.05). Myocardial oxygen extraction was unchanged, indicating that the decrease in oxygen consumption resulted from a reduction in myocardial oxygen demand. When heart rate and systolic pressure were artificially restored to control levels, after the administration of DMP, myocardial oxygen consumption remained significantly below the control level. DMP, therefore, appeared to reduce myocardial oxygen demands primarily by its negative inotropic effect. This drug may have application in the treatment of ischemic heart disease.
Late dysrhythmias and disturbances of conduction following Mustard operation for complete transposition of the great arteries.
Authors: Clarkson P M , Barratt-Boyles B G , Neutze J M
Published: June 2012

Between 1964 and 1971, 49 patients were discharged from hospital following atrial baffle repair for transposition of the great arteries. Electrocardiograms of 47 of these patients were available for review seven months to eight and a half years (average 31 months) after operation. Of the 46 patients in sinus rhythm prior to operation, 40 (87%) were in sinus rhythm with normal atrioventricular conduction when last seen. Four patients (8.7%) had benign supraventricular dysrhythmias: three were junctional, one was atrial. None was noted to experience rapid dysrhythmias. Two patients showed evidence of abnormal atrioventricular conduction. There were five late deaths but in only one of these patients was a dysrhythmia a possible factor. The effects of variations in caval cannulation, extent of excision of the atrial septum and placement of the baffle suture line on the rhythm present at last review were examined. To preserve sinus rhythm it appears necessary to avoid surgical trauma in the vicinity of both the sinus node and the A-V node. Preservation of the internodal tracts appears less important. It is uncertain whether the 'sinus' rhythm seen after operation originates in the sinoatrial node but the rhythm is functionally similar.
Common or single ventricle. An angiocardiographic and hemodynamic study of 42 patients.
Authors: Macartney F J , Partridge J B , Scott O , Deverall P B
Published: June 2012

To correlate anatomy with hemodynamics, the angiocardiographic findings were reviewed in 42 patients with common ventricle (CV). Nine had normally related great arteries (NRGA), 12 d-malposition, 21 l-malposition and 5 a common atrioventricular valve. Selective outlet chamber (OLC) angiocardiograms were available in 14 out of 29 patients with OLCs. OLC position varied from anterior and to the right of the CV to posterior and to the left of it; two categories (anterior and lateral OLC) were delineated by a line 45 degrees to theleft of anterior in the horizontal plane. The OLC was anterior in all patients with NRGA, lateral in most l-malpositions, and almost equally divided between anterior and lateral in d-malposition (P less than 0.05). Complete hemodynamic data were obtained in 29 patients. Complete mixing of venous return occurred in four patients with atresia of one valve. In the remainder complete mixing occurred in 36%, unfavorable streaming in 12% and favorable streaming in 52%. Semilunar valve position and pulmonary stenosis did not affect the nature of mixing. Systemic arterial (SA) minus pulmonary arterial O2 saturation was positive and significantly higher in patients with malposition with lateral OLCs than anterior OLCs (P less than 0.001). However 79% of SA O2 saturation variation could be predicted from pulmonary and systemic blood flow alone.
Right ventricular function in children with tetralogy of Fallot before and after aortic-to-pulmonary shunt.
Authors: Jarmakani J M , Nakazawa M , Isabel-Jones J , Marks R A
Published: June 2012

Right and left ventricular volume variables were obtained in 43 tetralogy patients undergoing diagnostic cardiac catheterization. The patient population consisted of 25 preoperative patients (group 1) and 18 patients who had undergone aortic-to-pulmonary shunt procedure (group 2). Volumes were calculated from biplane cineangiocardiograms using Simpson's rule method for the right ventricle (RV) and the area-length methods for the left ventricle (LV). In group 1, RV end-diastolic volume (RVEDV) was not different from normal in the total group and averaged 93 +/- 4% (SEM) of normal. In patients with hemoglobin (Hgb) greater than or equal to 16 g%, however, this variable was significantly (P = 0.044) less than normal. Right ventricular ejection fraction was normal and RV systolic index was significantly (P less than 0.001) reduced, averaging 3.35 +/- 0.18 (SEM) L/min/m2. Left ventricular volume variables in this group were not significantly different from RV volume variables. In group 2, RVEDV in patients with Hgb greater than or equal to 16 g% was significantly (P = 0.037) less than normal, but was normal in patients with Hgb less than 16 g%. Right ventricular ejection fraction averaged 0.52 +/- 0.03 in this group and was significantly (P less than 0.001) less than normal. Right ventricular systolic index (RVSI) averaged 3.51 +/- 0.24 L/min/m2 and was significantly (P = 0.009) less than normal. RVSI in patients with Hgb less than 16 g% averaged 3.90 +/- 0.31 and was not different from normal. In contrast, this variable in patients with Hgb greater than or equal to 16 g% averaged 3.21 +/- 0.34 and was significantly (P = 0.005) less than normal. Left ventricular end-diastolic volume (LVEDV) and LV systolic output in group 2 were significantly higher than RVEDV and RV systolic output. Right ventricular and LV ejection fractions in group 2 were not different. The relatively decreased ejection fraction fraction in tetralogy patients, as compared with patients with valvular pulmonic stenosis and similar volumes and pressures, suggests that the decreased ejection fraction was not due to decreased preload or increased afterload and might be due to impaired ventricular function secondary to chronic hypoxia. Early corrective surgery in these patients might reverse this process. However, patients with severe tetralogy who have small ventricular volume and reduced output might benefit from shunt procedure rather than complete correction.
Paradoxical embolism. A diagnostic challenge and its detection during life.
Authors: Cheng T O
Published: June 2012

Two cases of paradoxical embolism, one with recurrent cerebral embolism and one with brachial and coronary embolism and both associated with pulmonary embolism, were diagnosed during life. Although there was neither pulmonary hypertension nor intracardiac shunt present at the time of cardiac catheterization in both cases, the presence of a patent foramen ovale with an interatrial right-to-left shunt was demonstrated by a simple ascorbate dilution technique following a Valsalva maneuver. Each patient was treated by surgical interruption of the inferior vena cava and did well. Paradoxical embolism should be included in the differential diagnosis of arterial embolism for which there is no obvious source, especially when there is also evidence of venous thrombosis or pulmonary embolism.
Membranous subaortic stenosis complicated by aneurysm of the membranous septum and mitral valve prolapse.
Authors: Caudill C C , Krueger S K , Wilson C S , Rourke T , Policky D B , Weaver W F
Published: June 2012

The clinical, echocardiographic, and catheterization findings in a patient with discrete subaortic stenosis, aneurysm of the membranous interventricular septum, and mitral valve prolapse are presented. Echocardiography showed a subaortic membrane, abnormal aortic valve motion, accentuated systolic anterior motion of the membranous interventricular septum, and prolapsing mitral leaflets. Cardiac catheterization confirmed the diagnoses. The possible functional interrelationship of these lesions is discussed.
Salt, volume and the prevention of hypertension.
Authors: Freis E D
Published: June 2012

The evidence supporting the thesis that hypertension can be prevented by eliminating salt from the diet is based on four principal sources: (1) epidemiological studies in unacculturated peoples showing that the prevalence of hypertension is inversely correlated with the degree of salt intake; (2) hemodynamic studies suggesting that the development of chronic experimental hypertension is a homeostatic response to a maintained increase in extracellular fluid volume (ECF); (3) evidence that the ECF of "salt eaters" is expanded in comparison to that of "no-salt eaters"; and (4) investigations in hypertensive patients receiving either diets greatly restricted in salt or continuous diuretic therapy which correlate the fall in blood pressure with a reduction in ECF. Although this mechanism of essential hypertension is still obscure the evidence is very good if not conclusive that reduction of salt in the diet to below 2 g/day would result in the prevention of essential hypertension and its disappearance as a major public health problem.
Muscarinic effects of vagosympathetic trunk stimulation on the repetitive extrasystole (RE) threshold.
Authors: Rabinowitz S H , Verrier R L , Lown B
Published: June 2012

The precise mechanism of the vagus in opposing adrenergic influences on cardiac vulnerability has not been defined. In the present investigation, cholinergic stimulation was produced by administering the selective muscarinic agent methacholine (MCh) and ventricular vulnerability was assessed by measuring the repetitive extrasystole (RE) threshold. MCh produced a sustained 98 +/- 12% (P less than 0.0001) increase in the RE threshold; the increase was abolished by concurrent infusion of atropine (0.2 mg/kg). When MCh was administered during beta-adrenergic blockade with propranolol, however, no further increase in RE threshold occurred beyond that resulting from propranolol alone. Infusion of norepinephrine (NE), in a dose insufficient to provoke systemic hypertension, significantly lowered the vulnerable period threshold. This decrease was completely abolished by concurrent vagosympathetic stimulation (VS). It is concluded that VS affects ventricular vulnerability through its muscarinic action and that the protection against VF is in part due to modulation of neural and humoral beta-adrenergic inputs.
The contribution of tricuspid valve closure to the first heart sound. An intracardiac micromanometer study.
Authors: O'Toole J D , Reddy S P , Curtiss E I , Griff F W , Shaver J A
Published: June 2012

The sound-pressure correlates of the second high frequency component of a split first heart sound (S1) were investigated in 27 patients. An external phonocardiogram was recorded with high fidelity sound and pressure from the left and right atria in 21 patients, from the pulmonary artery in 14 of these, and from the central aorta in 11. In the remaining six patients, high fidelity recordings from the central aorta and right-sided chambers were obtained with an external phonocardiogram. The external component of S1 that coincided with a left atrial C wave and "internal sound" was defined as M1. In those cases where the left atrial pressure was not recorded, this component could be identified by a low frequency transient in the central aortic pressure trace. The other external high frequency component of S1 that was synchronous with a separate right atrial C wave and "internal sound" was defined as T1; with two exceptions, M1 preceded T1. The two exceptions which caused reversal of this order, so that T1 preceded M1, were due to chronic left bundle branch block and mitral stenosis. In both cases, T1 was shown to be distinctly separated from the upstroke of pressure rise in the central aorta. This finding was also demonstrated in three cases of right bundle branch block and one case with aortic valvular disease. The usual asynchrony of ventricular contraction was altered by induction of ventricular premature systoles; the separation of externally identifiable M1 and T1 components and their internal markers was predictably altered by this maneuver. The occurrence of T1 was variable in relation to the upstroke of the pulmonary artery pressure, which suggests that it is not related to pulmonic ejection. It is concluded that micromanometrically recorded right and left atrial C waves can serve as markers for externally recordable M1 and T1 components of the first heart sound. In addition, T1 is frequently an externally recordable and audible event.
Left ventricular function and adrenergic hyperactivity before and after saphenous vein bypass.
Authors: Boudoulas H , Lewis R P , Vasko J S , Karayannacos P E , Beaver B M
Published: June 2012

Forty patients with severe angina pectoris were studied before and two weeks after saphenous vein bypass surgery (SVG) in order to assess the effect of this operation on left ventricular performance as judged by systolic time intervals (STI). The patients were divided into two groups: group I included 29 patients in whom no postoperative infarction occurred and group II was composed of 11 patients with postoperative infarction. For group I the PEP/LVET was 0.39 +/- 0.01 preop and slightly but significantly increased at 0.42 +/- 0.004 (P less than 0.025) two weeks postop. The mean preop PEP/LVET was 0.33 +/- 0.01 for group II and dramatically increased to 0.54 +/- 0.02 (P less than 0.001) after surgery. Another striking abnormally was a marked shortening of electromechanical systole (QS2I), which was uniformly present in the postoperative studies. Follow-up studies in 16 patients and urinary catecholamine determination in five patients suggested excessive adrenergic activity was responsible for the abbreviated QS2I. This phenomenon must be considered when interpreting the results of SVG on left ventricular function.
Influence of dobutamine on regional myocardial blood flow and ventricular performance during acute and chronic myocardial ischemia in dogs.
Authors: Willerson J T , Hutton I , Watson J T , Platt M R , Templeton G H
Published: June 2012

The data from this study document that dobutamine is a powerful inotropic agent in anesthetized dogs with acute myocardial ischemia and in awake, unsedated ones with chronic myocardial infarction. Dobutamine significantly increases heart rate at relatively small doses in anesthetized dogs with acute myocardial ischemia but considerably larger amounts of dobutamine are required to significantly increase heart rate in awake, unsedated dogs with myocardial infarction. Dobutamine also significantly increases regional myocardial blood flow to all areas of the heart at 20mug/kg/min in both anesthetized dogs with acute myocardial ischemia and awake, unsedated ones with myocardial infarction. However, in anesthetized dogs 20mug/kg/min of dobutamine significantly increases epicardial ST-segment elevation during acute myocardial ischemia. Propranolol prevents the inotropic and chronotropic effects of dobutamine in both anesthetized and awake, unsedated dogs. This study suggests that during experimental acute myocardial ischemia dobutamine given at doses that significantly increase heart rate and contractility may increase the extent of myocardial damage. The data also suggest that this agent should be of value in the setting of severe myocardial depression without associated severe coronary artery disease to increase cardiac contractility at doses that do not markedly alter heart rate. The hemodynamic and coronary blood flow effects of dobutamine in patients with and without severe coronary artery disease should be evaluated.
Effect of intra-aortic balloon counterpulsation on the motion and perfusion of acutely ischemic myocardium. An experimental echocardiographic study.
Authors: Kerber R E , Marcus M L , Ehrhardt J , Abboud F M
Published: June 2012

The effect of intra-aortic balloon counterpulsation (IABC) on the motion and perfusion of ischemic left ventricular posterior myocardium was studied in 30 open-chest dogs, using ultrasound to register motion and 7-10 mu radioactive microspheres to determine perfusion. Circumflex coronary artery ligation produced acute aneurysmal bulging during isovolumetric contraction and diminished ischemic wall velocity during systolic ejection. Myocardial perfusion was determined in five dogs; perfusion of the area supplied by the ligated coronary artery fell from a control value of 72.9 +/- 13.8 (SE) to 30.0 +/- 2.3 cc/100 g/min (P less than 0.05) at 5 minutes after coronary occlusion. IABC was then administered for one hour, with a fall in aortic systolic pressure (112 +/- 6 to 105 +/- 7 mm Hg, P less than 0.05) and rise in peak aortic diastolic pressure (94 +/- 6 to 102 +/- 7 mm Hg, P less than 0.05). Despite this the ischemic area showed no change in perfusion (measured at the same time): 30.0 +/- 2.3 to 28.0 +/- 2.4 cc/100 g/min. Little change in wall motion occurred: aneurysmal bulging decreased modestly (4.5 +/- 0.3 to 3.6 +/- 0.3 mm, P less than 0.05), but ischemic wall velocity did not increase. After cessation of counterpulsation and one hour of coronary reperfusion aneurysmal bulging disappeared and wall velocity improved. The addition of norepinephrine (eight dogs) or nitroprusside (seven dogs) to intraaortic balloon counterpulsation did not cause a significant further improvement in the response of the dyskinesis during the period of ischemia. We conclude that IABC has little effect on ischemic dyskinesis, probably due to its failure to improve perfusion of the acutely ischemic myocardium.
Parachute accessory anterior mitral valve leaflet causing left ventricular outflow tract obstruction. Report of a case with emphasis on the echocardiographic findings.
Authors: Cooperberg P , Hazell S , Ashmore P G
Published: June 2012

A case of left ventricular outflow tract obstruction caused by a parachute accessory anterior mitral valve leaflet is presented. The abnormality was detected in an asymptomatic patient by systolic murmur and thrill and was demonstrated by echocardiography, as well as by cardiac catheterization and surgery. These findings are presented. Several previously reported cases of a similar nature are reviewed. An identical case was not found in the English literature.
Anomalies of the aortic arch and ventricular septal defects.
Authors: Moulaert A J , Bruins C C , Oppenheimer-Dekker A
Published: June 2012

This investigation presents additional evidence for the hemodynamic influence of intracardiac anomalies on the development of the aortic arch, based on measurements of different parts of the great vessels. Criteria are given to define the normal aortic arch and the different anomalies of the aortic arch, such as interruption, atresia, tubular hypoplasia, hypoplasia, abnormal long segment and juxtaductal coarctation. Two types of of malignment venentricular septal defects are described to illustrate how prenatal intracardiac flow disturbances can account for various aortic arch patterns. An explanation is proposed as to how reduced blood flow through the embryonic preductal aorta may contribute to the pathogenesis of all dimensional anomalies of the aortic arch.
Left axis deviation: a spectrum of intraventricular conduction block.
Authors: Das G
Published: June 2012

The effects of left axis shift (greater than -30 degrees) on intraventricular conduction time (IVCT) were studied in 63 subjects in whom electrocardiograms before and after appearance of the left axis shift were available. Subjects with electrocardiographic evidence of left or right ventricular hypertrophy, left or right bundle branch block, myocardial infarction, pre-excitation and those receiving antiarrthymic drugs were excluded. The IVCT increased by an average of 25 msec when the QRS axis shifted to -30 degrees or beyond. When the individual AQRS was related to the IVCT a linear correlation (r = -0.8) was observed. It appears that a continuum relation between the AQRS and the IVCT exists throughout the counterclockwise range of +90 degrees to -90 degees. In all leftward shifts in AQRS from from +90 degrees there is a prolongation in IVCT. Our observations indicate that all leftward shifts in AQRS, including the extreme left axis shift (left anterior hemiblock), represent a spectrum of intraventricular conduction block.
The vectorcardiogram in right bundle branch block: correlation with cardiac failure and pulmonary disease.
Authors: Fedor J M , Walston A , Wagner G S , Starr J
Published: June 2012

Frank vectorcardiograms (VCG) and clinical records of 243 patients with right bundle branch block (RBBB) were compared. The patients were classified into three categories on the basis of VCG criteria. The first category included 100 patients with a normal frontal axis, and the second category included 44 patients with concomitant left anterior hemiblock. The third category consisted of 99 patients with RBBB and myocardial infarction. The VCGs were classified into three types accoriding to the QRS configuration in the transverse plane. In type I the initial forces were anterior and counterclockwise and the afferent limb crossed the midline posterior to E point; in type II the initial forces were anterior and counterclockwise and the afferent limb crossed the midline posterior to E point; in type II the initial forces were anterior and counterclockwise and the afferent limb crossed the midline anterior to or through E point; and in type III the entire transverse loop was clockwise and anterior to E point. The patients were further classified according to the presence or absence of cardic failure or severe pulmonary disease. In patients with RBBB and a normal axis, cardiac failure or severe pulmonary disease was found in five of 49 patients wtih type I, 17 of 31 with type II, and 18 of 20 with type III pattern. In patients with RBBB and left anterior hemiblock, significant disease was found in one of 17 with type I, five of 16 with type II, and eight of 11 with type III pattern. These data show that, in patients with RBBB, the position of the afferent limb in the transverse plane can be used to predict cardiac failure or severe pulmonary disease.
The influence of left ventricular stroke volume on aortic root motion: an echocardiographic study.
Authors: Pratt R C , Parisi A F , Harrington J J , Sasahara A A
Published: June 2012

Aortic root motion was studied in 24 normal volunteers at rest and during the Valsalva maneuver, isometric exercise, and amyl nitrite inhalation. In addition root motion was correlated with the stroke volumes determined at cardiac catheterization in 24 patients. The root has distinct systolic movement, the amplitude and duration of which were easily measured both at rest and during the interventions. At rest,the mean (+/-1 SE) systolic amplitude of the anterior aortic wall was 11.2 +/- 0.5 mm and that of the posterior wall 9.5 +/- 0.3 mm. During the strain phase of the Valsalva maneuver anterior wall amplitude fell to 8.2 +/- 0.4 mm and the posterior wall to 7.3 +/- 0.5 mm (P less than 0.001). With release, anterior wall amplitude rebounded to 12.5 +/- 0.8 mm and the posterior wall to 10.8 +/- o.5 mm, values greater than control (P less than 0.01). With isometric exercise there was no change in amplitude compared to rest; however, amyl nitrite caused an increase in the anterior wall to 13.5 +/-0.8 mm and posterior wall to 11.9 +/-0.6 mm (P less than 0.01). In the patient group the amplitude of posterior wall motion correlated weakly with cardiac index (r = 0.63) and stronger with stroke index (r = 0.78). This study quantifies the echocardiographic pattern of normal aortic root motion. The findings indicate that the aortic root motion is an index of stroke volume; they further suggest that root motion is acutely sensitive to variations in stroke volume since its amplitude changed in accord with the documented effects of the employed maneuvers on stroke volume.
Myocardial ischemia due to infrarenal aortic cross-clamping during aortic surgery in patients with severe coronary artery disease.
Authors: Attia R R , Murphy J D , Snider M , Lappas D G , Darling R C , Lowenstein E
Published: June 2012

Hemodynamic measurements were performed and ECG recorded before and shortly after infrarenal aortic cross-clamping during operation for abdominal aortic aneurysm in five patients without evidence of heart disease (group I) and in ten patients with severe coronary artery disease (group II). All patients sustained an increase in systemic arterial pressure. Group I demonstrated a decrease in pulmonary artery, pulmonary capillary wedge (PCW), and central venous pressures when the aorta was clamped, whereas group II demonstrated an increase. The difference in response of the groups is significant (P less than 0.05). All three patients who responded to cross-clamping with increases of 7 mm Hg or greater in PCW demonstrated myocardial ischemia during cross-clamping. None of the values measured prior to cross-clamping predicted with certainty the response to cross-clamping. Sodium nitroprusside reversed the elevation of left ventricular filling pressure in all three patients, and in two patients, relieved evidence of myocardial ischemia concurrently. In the third patient, ventricular irritability was abolished by lidocaine and did not recur. We conclude that infrarenal aortic cross-clamping may cause myocardial ischemia in patients with severe coronary artery disease. This ischemia may be predicted by a rise in PCW at the time of cross-clamping, and vasodilator therapy is indicated in such patients.
Diagnosis of acute myocardial infarction in a community hospital: significance of CPK-MB determination.
Authors: Roark S F , Wagner G S , Izlar H L , Roe C R
Published: June 2012

Twice-daily CPK-MB determinations were performed but not made availabe to the physicians of 179 consecutive patients with precordial pain admitted to a community hospital to evaluate the diagnostic importance of this isoenzyme. Physician decision was based upon history and once-daily ECG and total enzymes (CPK, SGOT, LDH). Following hospital discharge, each patient's clinical record was reviewed to determine the physician diagnostic decision. The patients were subdivided into three groups. The first group consisted of 46 patients with diagnostic QRS changes and elevated total enzymes. All 46 had physician diagnosis of acute myocardial infarction and CPK-MB was present in 44 (96%). The second group included 55 patients with nondiagnostic QRS but elevated total enzymes. Physician diagnosis was acute myocardial infarction in 28 (51%) but 16 (57%) of these had no CPK-MB. The third group contained 50 patients with nondiagnostic QRS and normal enzyme levels. Six (12%) had physician diagnosis of acute myocardial infarction but none had CPK-MB. Thus, absence of CPK-MB failed to confirm physician diagnosis of acute myocardial infarction when based upon history and total enzymes in the absence of QRS changes in 22 of 34 (65%) patients.
Effects of procainamide on the dispersion of recovery of excitability during coronary occlusion.
Authors: Levites R , Haft J I , Calderon J , Venkatachalapathy
Published: June 2012

In 14 mongrel dogs, refractory periods were determined in nonischemic and acutely ischemic zones of myocardium during control conditions, 15 minutes after coronary ligation, and 10 and 20 minutes after a procainamide infusion. Following coronary ligation, refractory periods in the nonischemic area remained unchanged (100.8% of control) while in the ischemia area they decreased to 88.6% of control (P less than 0.02) causing a dispersion of refractoriness of 12.2%. After the administration of procainamide, refractory periods lengthened in the nonischemic as well as in the ischemic areas but the changes were such that the temporal dispersion caused by the coronary ligation was reduced from 12.2% to 5.5% (P less than 0.01) after 10 minutes, and to 5.0% (P less than 0.02) after 20 minutes of drug infusion. It is concluded that procainamide exerts different overall effects on the nonischemic and acutely ischemic canine myocardium. It is postulated that this action may play a role in the suppression of re-entrant arrhythmias.
Noninvasive detection of intracardiac thrombosis: 131-I fibrinogen cardiac survey.
Authors: Frisbie J H , Tow D E , Sasahara A A , Barsamian E M , Parisi A F
Published: June 2012

Cardiac survey following administration of 131-1 autologous fibrinogen is a noninvasive technique for the detection of intracardiac thrombosis. Fibrinogen is isolated from plasma by a rapid salting-out method with ammonium sulfate and is iodinated with chloramine T. The purity of 131-fibrinogen, expressed as clottable radioactivity, is greater than 90%. Cardiac survey consisting of serial gamma camera imaging or rectilinear scanning after intravenous administration of 131-I fibrinogen was conducted in dogs with freshly induced thromobosis of the left atrial appendage. An accumulation of radioactivity was detectable in the area of the left atrium and confirmed in each of nine dogs sacrificed. Similarly, 20 patients with heart disease predisposing to intracardiac thrombosis were surveyed. Eight of nine patients with positive studies and 11 of 11 with negative studies were confirmed subsequently at surgery or autopsy. Cardiac survey with 131-I fibrinogen is a simple and noninvasive method of detecting intracardiac thrombosis.
Alterations of right ventricular systolic time intervals by chronic pressure and volume overloading.
Authors: Curtiss E I , Reddy P S , O'Toole J D , Shaver J A
Published: June 2012

Right ventricular (RV) systolic time intervals and hemodynamic parameters were determined by micromanometric techniques in 13 subjects with normal right ventricles (NRV). These data were compared to those of 16 patients with pulmonary hypertension (PH) or predominant pressure overloading and 13 individuals with uncomplicated secundum atrial septal defects (ASD) or predominant volume overloading. In PH, the QP2 interval tends to remain within the normal range due to reciprocal changes in isovolumic contraction (ICT) and ejection (RVET) times. Elevations of pulmonary artery diastolic pressure are associated with increases in the mean rate of isovolumic pressure rise (MRIPR) (r = 0.84), but the latter change does not fully compensate for the widened ventriculoarterial diastolic pressure difference and ICT becomes prolonged (P less than 0.001). Factors other than stroke index depression which may contribute to the decreased duration of RVET (P less than 0.001) include tricuspid regurgitation and elevation of pulmonary vascular impedance. In ASD, QP2 is significantly prolonged (P less than 0.025) due to a significant increase in RVET (P less than 0.005). In contrast to NRV, a linear correlation of RVET and stroke index was not present, which suggested an alteration of ejection dynamics in this group. Despite a high incidence of complete or incomplete right bundle branch block the interval from QRS onset to rapid RV pressure upstroke was not prolonged. This is most probably the result of peripheral bundle branch block of genesis of the QRS pattern by right ventricular hypertrophy.
The surgical management of discrete and diffuse supravalvar aortic stenosis.
Authors: Keane J F , Fellows K E , LaFarge C G , Nadas A S , Bernhard W F
Published: June 2012

Between 1956 and 1976, 18 patients underwent surgery for supravar aortic stenosis at the The Children's Hospital Medical Center, Boston. Discrete obstruction, present in 11, was treated by insertion of a prosthetic gusset placed across the area of narrowing and extending into the noncoronary sinus of Valsalva. There was one operative death. Residual gradients (measured in five patients) ranged from 4-55 mm Hg, one of which was supravalvar in location. Significant aortic regurgitation was not common preoperatively. The diffuse form of supravalvar obstruction, a more difficult surgical problem, was present in seven patients. There were three operative deaths. Complete relief of the pressure gradient was achieved only in one instance by insertion of a left ventricular-aortic bypass shunt diverting the majority of the cardiac output into the descending thoracic aorta. This patient is now asymptomatic 20 months following operation. On the basis of this experience, it is suggested that patients with the diffuse form of supravalvar obstruction, and perhaps even those with a hypoplastic annulus alone, would benefit from a left ventricular-aortic bypass shunt.
Transatrial resection of the obstructed right ventricular infundibulum.
Authors: Edmunds L H , Saxena N C , Friedman S , Rashkind W J , Dodd P F
Published: June 2012

Obstructions of the right ventricular infundibulum were resected through the orifice of the tricuspid valve in 21 patients, 15 of whom had tetralogy of Fallot. At operation the systolic pressure difference between the right ventricle and pulmonary artery after repair averaged 18 mm Hg (range 0-40 mm Hg). In patients with tetralogy, cardiac index four hours after operation averaged 2.8 L/M2/min. One patient with tetralogy and severe pulmonary hypertension died. Twelve patients with tetralogy were recatheterized 10 to 186 days after operation. The mean systolic pressure difference between right ventricle and pulmonary artery was 23 mm Hg. Residual obstructions were in the pulmonary valvular annulus. Cineangiograms did not show paradoxical motion of the right ventricular wall. Transatrial resection of right ventricular infundibular obstructions carries with it none of the consequences that often follow right ventriculotomy and this surgical approach satisfactorily relieves infundibular obstructions.
Failure of demand pacing with small surface area electrodes.
Authors: Hughes H C , Brownlee R R , Tyers G F
Published: June 2012

As pacemaker electrode myocardial contact area is reduced, the energy required to stimulate the heart decreases; but the effect of surface area on an electrode's ability to transmit R-wave potentials has not been well documented. Endocardial and intramyocardial R-wave potentials were measured in ten dogs with seven commercially available pacemaker electrodes of different surface area. With a load impedance of 1000 ohms, there was a direct correlation between surface area and the R-wave potentials measured. The amplitude of the R-wave that resulted from conduction from the heart to the sensor via the electrode system decreased with decreasing surface area. A similar direct correlation was seen between the R-wave potentials measured and the threshold current and energy requirements. With the present trend toward utilization of small surface area electrodes to reduce pacemaker cell drain, care must be taken to optimize pacemaker circuit impedance if sensing problems are to be avoided.
The mechanisms of supraventricular tachycardia in children.
Authors: Gillette P C
Published: June 2012

The mechanisms of supraventricular tachycardia were investigated in 35 children. Intracardiac electrograms including His bundle potentials were recorded. Atrial pacing and single premature atrial stimuli were performed in the right atrium. Tachycardia was observed and the mechanism elucidated in 33 patients. The atrial activation sequence during tachycardia, including high right atrium, low lateral right atrium, low septal right atrium, and left atrium, together with the ability to initiate or terminate the tachycardia with premature stimuli, were keys to defining the mechanisms. The observed mechanisms included atrioventricular (A-V) node reentry (8), sino atrial node re-entry (5), re-entry through manifest or concealed lateral anomalous pathway (8), re-entry through A-V node bypasses (3), and atrial (7) and junctional (2) ectopic focuses. The frequency of the various mechanisms of SVT is more varied in children than adults, with ectopic mechanisms being more common in children.
The significance of the left atrial appendage in rheumatic heart disease.
Authors: Kelley M J , Elliott L P , Shulman S T , Ayoub E M , Victorica B E , Gessner I H
Published: June 2012

The possible diagnostic value of an enlarged left atrial appendage (LAA) on the posterior-anterior or right anterior oblique chest film as a means of implicating a rheumatic etiology for mitral valve disease in children was investigated. Chest films were examined without prior knowledge of clinical or laboratory data, and the results were later correlated with this information in 113 children and adolescents. The clinical and laboratory data included application of the modified Jones criteria for the diagnosis of acute rheumatic fever, streptococcal antibody titers and clinical and cardiac catheterization findings. In children with mitral valve disease, our data suggest that as enlarged LAA, especially in the presence of pulmonary venous obstruction, is characteristic of rheumatic heart disease. This finding appears to be particularly useful, in conjunction with streptococcal antibody studies, in distinguishing rheumatic from nonrheumatic patients with mitral insufficiency.