bluuebunny/crossref_metadata_2025 huggingface dataset:
Truncus arteriosus with unilateral absence of a pulmonary artery. Criteria for operability and surgical results.
Authors: Mair D D , Ritter D G , Danielson G K , Wallace R B , McGoon D C
Published: June 2012

In 15 of 126 (12%) patients with truncus arteriosus who were catheterized at the Mayo Clinic from 1967 through 1975, natural agenesis of one pulmonary artery was present. Ten truncus patients with either natural or acquired absence of one pulmonary artery have undergone definitive operation. The criteria for operability, based on a calculation of pulmonary resistance, are different in patients with single pulmonary artery than in patients with two pulmonary arteries. Study revealed that, if the calculated pulmonary resistance in the patient with single pulmonary artery is halved, this new value provides a more reliable assessment of the reactivity of the pulmonary arteriolar bed than does the total calculated pulmonary resistance value. Follow-up information suggests that the patient with single pulmonary artery may be at potentially high risk of continued progression of pulmonary vascular disease after surgical correction, possibly because of the postoperative obligatory increased flow through the single pulmonary arteriolar bed as a result of the entire cardiac output passing through it. Surgical correction of truncus arteriosus during infancy, before significant pulmonary vascular disease has developed, appears to be particularly desirable in this subgroup of patients with single pulmonary artery.
Re-entrant ventricular arrhythmias in the late myocardial infarction period. 1. Conduction characteristics in the infarction zone.
Authors: El-Sherif N , Scherlag B J , Lazzara R , Hope R R
Published: June 2012

Dogs 3-7 days following ligation of the anterior descending coronary artery representing a remarkably stable model for re-entrant ventricular arrhythmias (RVA) and allowed detailed electrophysiologic studies of the re-entrant mechanism. In these dogs, we could regularly illustrate the presence of continuous electrical activity originating from the infarction zone (IZ) and bridging the diastolic interval between the initiating and re-entrant beats as well as between consecutive re-entrant beats. Conduction in the IZ was highly complex, with multiple potentially re-entrant pathways, functionally dissociated areas, and areas of localized ventricular fibrillation. Conduction disorders in ischemic myocardium were consistently tachycardia-dependent with the spontaneous onset of RVA specifically associated with a Wenckebach-like conduction pattern in a potentially re-entrant pathway. Both manifest and concealed re-entry, as well as re-entrant beats with regular extrasystolic grouping, constant or variable coupling, uniform multiform and bidirectional QRS configurations, were related to characteristic conduction patterns in the IZ. In summary, the study provides the first direct in vivo evidence of ventricular re-entry and demonstrates propensity for RVA and sudden death in the late myocardial infarction period.
Re-entrant ventricular arrhythmias in the late myocardial infarction period. 2. Patterns of initiation and termination of re-entry.
Authors: El-Sherif N , Hope R R , Scherlag B J , Lazzara R
Published: June 2012

The electrophysiologic mechanisms for the initiation and termination of re-entrant ventricular arrhythmias (RVA) were critically analyzed in dogs 3-7 days following ligation of the anterior descending coronary artery, utilizing direct recordings of the re-entrant pathway (RP) from the epicardial surface of the infarction zone. Re-entry could occur during a regular cardiac rhythm if the heart rate is within the narrow critical range during which conduction in a potentially RP exhibits a Wenckebach-like (W) pattern with a beat-to-beat increment of conduction delay until the activation waveform is sufficiently delayed to re-excite normal myocardium. If a regular cardiac rhythm is associated with limited conduction delay in a potentially RP, premature beats within a critical range of coupling intervals could result in sufficient conduction delay to induce re-entry. Re-entrant ventricular arrhythmias may be unmasked on abrupt termination of a critical fast rate of cardiac pacing only if pacing was terminated during those beats of a W pattern associated with marked conduction delay in a RP. RVA could be ended by one or more properly timed premature beats that would pre-excite part of the RP. An electrophysiologic mechanism for R-on-T and its relationship to onset of ventricular fibrillation was shown, based on markedly delayed RP conduction of the beat prior to the one apparently coupled to the premature beat.
Natriuretic response to saline infusion in normotensive and hypertensive man. The role of renin suppression in exaggerated natriuresis.
Authors: Luft F C , Grim C E , Willis L R , Higgins J T , Weinberger M H
Published: June 2012

Previous studies have reported an exaggerated natriuresis in hypertensive man; however, a systematic appraisal of this response in various forms of hypertension has not been made. We measured fractional excretion of sodium (FENa) during a four hour intravenous infusion of 2 liters normal saline in 162 normal subjects and 120 hypertensives. Of these, 13 had primary aldosteronism (ALDO), 19 high renin (HRH), 30 low renin (LRH), and 57 normal renin (NRH) essential hypertension. FENa for normals (1.42%), NRH (1.57%), and HRH (1.46%) was similar. That for LRH (2.56%) and ALDO (4.18%) was elevated compared to the other three subgroups (P less than 0.001). Although the four hour FENa during saline infusion was associated with mean atrterial blood pressure (MABP) within the entire hypertensive population (r = 0.51), when the subgroups of the hypertensive patients were considered separately no association between FENa and MABP was identified. Moreover, the MABP of subjects with HRH was greater (P less than 0.05) than in those with NRH, although the FENa of the two subgroups was similar. Patients with ALDO and LRH have a greater natriuretic response to a salt load than do other subgroups of essential hypertension or normal subjects. The exaggerated natriuresis appears to be a feature of hypertension with renin suppression. The degree of exaggerated natriuresis in not solely a function of an elevated mean arterial blood pressure.
Graded global ischemia and reperfusion. Cardiac function and lactate metabolism.
Authors: Apstein C S , Deckelbaum L , Mueller M , Hagopian L , Hood W B
Published: June 2012

The effect of global ischemia of different degrees of severity and reperfusion was studied in the isolated working rat heart. Four degrees of ischemia were induced by reducing the control total coronary flow of 8 ml/min to 0, 0.04, 0.4, or 0.8 ml/min for 30 minutes, after which the coronary flow was returned to the control level. After severe ischemia (0 and 0.04 ml/min ischemic coronary flow groups), recovery of contractility was to less than 30% of the control, pre-ischemic value of ventricular developed pressure and dP/dt, and irreversible cardiac contracture and an increased pacing threshold occurred. After moderate ischemia (0.4 and 0.8 ml/min ischemic coronary flow groups), contractile function recovered completely, ischemic contracture was rapidly reversible and the pacing threshold did not increase. The moderately ischemic groups were able to function at a stable, low level of contractility for the 30 minute ischemic period, whereas the severely ischemic groups had no contractile activity. The amount of calculated tissue lactate accumulation correlated with the occurrence of irreversible ischemic injury; the severely ischemic groups which failed to recover with reperfusion accumulated 3-5 times as much lactate as the moderately ischemic groups which recovered completely. The results suggest that relatively small differences in the severity of the ischemic condition can markedly affect the degree of tissue injury.
Angiographic determination of arterial patency after percutaneous catheterization in infants and small children.
Authors: Hurwitz R A , Franken E A , Girod D A , Smith J A , Smith W L
Published: June 2012

Patency of the femoral artery of infants and children who previously had percutaneous arterial catheterization at a weight of less than 25 kg was studied angiographically. During the study period, 118 patients had repeat arterial catheterization. 48 from the opposite leg. Femoral artery occlusion was found in four patients, while 44 of the 48 studied from the opposite leg had complete patency. At the later study, all four with blockage were asymptomatic and possessed good pedal pulses, while two had decreased femoral pulsations. When events surrounding initial catheterization were retrospectively analyzed, three of four had decreased pedal pulsations beyond six hours. It is concluded that 3-8% of patients weighing less than 25 kg have arterial occlusion after catheterization. This complication may be entirely asymptomatic, but these patients will require continued observation for possible late vascular problems.
The effects of left ventricular load and contractility on mitral regurgitant orifice size and flow in the dog.
Authors: Borgenhagen D M , Serur J R , Gorlin R , Adams D , Sonnenblick E H
Published: June 2012

Acute mitral regurgitation (MR) was produced in 12 dogs by closed chest partial valvulectomy and the relative contributions of MR pressure gradient (MRG), the time for regurgitant flow (VSI), and the MR orifice area (MRA) to mitral regurgitant volume (MRV) assessed. Aortic and left atrial pressures, biplane left ventricular (LV) angiography, forward flow and mitral regurgitant flow (MRF) were measured following MR induction and following augmentation of left ventricular end-diastolic volume (EDV), increased aortic resistance (angiotensin), and in the presence of increased ventricular contractility (calcium or epinephrine). Mitral regurgitation orifice area was determined by calculation and the diameters of the mitral anulus and subvalvular areas measured angiographically. Angiotensin and volume infusion induced a substantial increase in MRF which was largely dependent on an increase in MRA but not MRG, while augmentation of contractility decreased MRF accompanied by a decrease in MRA, relatively independent of MRG. Left ventricular size and shape are major determinants of MRA and resultant MRF in acute mitral regurgitation. These findings may help to explain the effects of such factors as ventricular loading and volume on the clinical course of mitral regurgitation in man.
Effect of clofibrate on intravascular coagulation in hyperlipoproteinemia.
Authors: Carvalho A C , Lees R S , Vaillancourt R A , Colman R W
Published: June 2012

Intravascular coagulation (IVC) was evaluated in 19 patients with type II and 11 with type IV hyperlipoproteinemia before and after clofibrate therapy by measurements of soluble fibrin complexes (SFC) in plasma; fibrinolysis was estimated by quantitation of fibrin (ogen) degradation products in serum. Untreated type II and type IV patients had increased SFC (P less than 0.01). The former also had activation of the intrinsic coagulation pathway as evidenced by decreased plasma prekallikrein (P less than 0.001), kallikrein inhibitors (P less than 0.001), and factor XII (P less than 0.02). Although clofibrate treatment of the type II patients did not change plasma lipids, it decreased intravascular coagulation, apparently via decreased factor XII activation and stimulation of fibrinolysis. In contrast, treated type IV patients had unchanged SFC and FDP levels, despite decreased plasma triglycerides (P less than 0.01). Clofibrate-induced changes in blood coagulation are independent of lipid-lowering. Clofibrate therapy decreases intravascular coagulation in type II patients and may help to prevent thromboembolic sequelae.
Cranial and caudal augulation for coronary angiography revisited.
Authors: Sos T A , Baltaxe H A
Published: June 2012

Several similar projections utilizing cranial and caudal angulation of the X-ray tube in various obliquities have been described recently for coronary angiography and left ventriculography. These views provide improved visualization of the proximal branches of the left coronary artery, the region of the crux of the right coronary artery, and the left ventricle in the left anterior oblique projection; structures which in the conventional projections are often superimposed on one another or are foreshortened. The confusing and conflicting terms--"oblique clockwise and anticlockwise table base turn," "half-axial," "angulated," "sit up," "caudo-cranial sagittal augulation," "cranio-caudal sagittal angulation," and "lordotic" projections--should be discarded in favor of the terms "cranial angulation projection" and "caudal angulation projection." The appropriate anterior, rather than the posterior obliquity should be used to refer to rotation of the patient, or the X-ray beam around his long axis.
Congenitally complete heart block. Developmental aspects.
Authors: Anderson R H , Wenick A C , Losekoot T G , Becker A E
Published: June 2012

Three cases of congenitally complete heart block are described of hearts in which other minor congenital malformations were not in themselves severe enough to disrupt the atrioventricular conduction system. The cases fitted well into the categorization of complete heart block suggested by Lev. Two exhibited lack of communication between the atrial and conducting tissues, the other had discontinuity of the penetrating atrioventricular bundle. In an attempt to explain why this discontinuity between different segments of the conducting tissues occurs, we re-examined several series of graded human embryos. This investigation suggested that the anulus fibrosus in the normal heart is derived from sulcus tissue of the atrioventricular junction, the endocardial atrioventricular cushions playing a minor role in the separation of atria from ventricles. The relationships between the sulcus tissues and the different components of the atrioventricular junctional area are discussed in terms of an explanation both for the existence of different types of congenitally complete heart block and for persistence of Mahaim (nodo-ventricular and nodo-fascicular) fibers.
The extraction of thallium-201 by the myocardium.
Authors: Weich H F , Strauss H W , Pitt B
Published: June 2012

The concentration of thallium-201 in the myocardium immediately following injection of tracer is the result of both blood flow delivering tracer to the heart and extraction by the myocardium. In these studies, the extraction of thallium-201 by the canine myocardium was determined as a function of heart rate, coronary blood flow, hypoxia, changes in pH, and following administration of propranolol, insulin, and strophanthin. Under basal conditions, extraction fraction measured 88 +/- 2.1%, following pacing to a rate of 195 beats/min extraction fraction remained unchanged at 88.5%. Similar results were found with changes in pH, propranolol, insulin, and strophanthin. Hypoxia caused a significant decrease in extraction fraction to 77.9%. When coronary blood flow was increased in excess of demands by drugs, extraction fraction fell logarithmically.
Continued incorporation of circulating radiolabeled fibrinogen into preformed coronary artery thrombi.
Authors: Salimi A , Oliver G C , Lee J , Sherman L A
Published: June 2012

This study measured the growth over time of experimental coronary artery (CA) thrombi by radiolabeled fibrinogen uptake. 125I-fibrinogen was injected into dogs and 24 hours later CA thrombi were induced by electrical current. Twenty-four hours after CA thrombus induction, 131I-albumin (group A) or 131I-fibrinogen (group B) was injected. At 48 hours after thrombi induction, the thrombi were removed, divided into segments, and their radioactivity measured. The 131I-fibrinogen in the group B thrombi was significantly greater than the 131I-albumin in group A thrombi (P less than 0.001). In further studies, the 131I-fibrinogen was given 48 and 72 hours post CA thrombus formation. Significant 131I was also found in these CA thrombi. 125I-fibrinogen and 131I-fibrinogen incorporation occurred in virtually all segments of the thrombi. The results suggest 1) CA thrombi growth continues for at least 72 hours after initial formation; 2) the presence of 131I in the thrombi was due to gradual fibrin deposition throughout the thrombus.
Digitalis in the pre-excitation syndrome. Analysis during atrial fibrillation.
Authors: Sellers T D , Bashore T M , Gallagher J J
Published: June 2012

The effect of digitalis in 21 patients with Wolff-Parkinson-White syndrome was anlayzed with respect to the ventricular response during atrial fibrillation and antegrade and retrograde refractory periods of accessory pathways. Digitalis shortened the cycle length of the most rapid ventricular response (shortest R-R) (i.e., increased the ventricle response) in 6/21 patients, increased the cycle length in 7/21 patients, had no effect on the cycle length in 5/21, and could not be determined in 3/21. Digitalis could be directly related to the onset of ventricle fibrillation resulting from atrial fibrillation in 9/21 patients. Each of these patients had shortest R-R intervals (220 msec or less) during atrial fibrillation in the control data. The results of this study indicate that no a priori prediction about the effect of digitalis on the antegrade conduction of accessory pathways can be made. By elective induction of atrial fibrillation it is possible to separate WPW patients into groups at high and low risk for developing ventricular fibrillation with the administration of digitalis.
Influence of mannitol on maintaining coronary flows and salvaging myocardium during ventriculotomy and during prolonged coronary artery ligation.
Authors: Fixler D E , Buja L M , Wheeler J M , Willerson J T
Published: June 2012

We investigated whether prolonged infusion of hypertonic mannitol results in a sustained increase in coronary flow and reduces myocardial necrosis after ventriculotomy or two hours of circumflex coronary artery occlusion. Cardiac outputs, intracardiac pressures, and heart rates did not differ between mannitol and control animals. Those receiving mannitol after ventriculotomy had coronary flows to myocardium near the incision which did not differ from controls. During coronary occlusion, mannitol did increase flow to ischemic and peri-ischemic regions by one hour, but this increase was not sustained at two hours. On histologic examination, myocardial necrosis involving the right ventricular free wall in the ventriculotomy animals and the posterior papillary muscle and subadjacent free wall in the coronary occlusion animals, did not differ between the mannitol treated and control groups. The data obtained in the present study, combined with those from earlier evaluations of the influence of mannitol during ventriculotomy and myocardial ischemia, suggest that mannitol's ability to increase coronary flow to injured areas of myocardium is relatively short-lived.
The cardiovascular effects of the continuous infusion of dobutamine in patients with severe cardiac failure.
Authors: Leier C V , Webel J , Bush C A
Published: June 2012

Twenty-five patients with left ventricular failure and low cardiac output received a 72 hour infusion of dobutamine (10-15 microgram/kg/min) in order to determine the cardiovascular properties of this new inotropic agent. Left ventricular contractile performance improved significantly during the infusion as measured by systolic time intervals and echocardiographic parameters. Mean PEP/LVET decreased from 0.76 +/- 0.03 to 0.58 +/- 0.03 (P less than 0.05). The percent change in internal dimension of the left ventricle from diastole to systole increased from 9.5 +/- 1 to 16.8 +/- 1 (P less than 0.05) and Vcf increased from 0.47 +/- 0.05 to 0.80 +/- 0.06 circ/sec (P less than 0.05). Mean cardiac output (nine patients) rose from 1.97 +/- 0.15 to 3.33 +/- 0.50 L/min/m2 while mean pulmonary capillary wedge pressure fell from 28 +/- 3 to 18 +/- 2 mm Hg during the infusion period (both P less than 0.05). These changes in cardiac function occurred without significant changes in heart rate, ventricular irritability, or blood pressure. Urine flow and urine sodium concentration increased during the infusion period. The improvement of cardiac function without the simultaneous development or exacerbation of undesirable effects (tachycardia, premature ventricular contractions, increased pulmonary or systemic resistance, tachyphylaxis, etc.) makes dobutamine a highly desirable inotropic agent.
The status of cardiovascular health knowledge among sixth, seventh, and eighth grade children.
Authors: White C W , Albanese M A , Anderson E E , Caplan R M
Published: June 2012

The goals of this study were to develop and standardize a test of cardiovascular health knowledge to determine its status among primary school children, to ascertain the rate at which cardiovascular health knowledge increases as compared to other subject areas, and to demonstrate the feasibility of the use of standardized achievement tests for assessing the results of health education curricula. The Iowa Cardiovascular Health Knowledge Test (ICVHT) was developed and administered in conjunction with a standardized educational testing program, the Iowa Test of Basic Skills (ITBS), to a stratified sample of 2,675 Iowa Students from grades six, seven, and eight. The average student in the sixth, seventh and eighth grades answered 37.9 +/- 0.4, 41.2 +/- 0.3, and 43.7 +/- 0.4 (SEM) percent of the items correctly. ICVHT scores increased minimally (less than 1 item/grade) as grade levels increased, but at a 75% slower rate than scores in other subjects tested. The results document a deficiency in cardiovascular health knowledge and provide a model for use in educational assessment programs in other health disciplines.
The enlargement of small pulmonary arteries by preliminary palliative operations.
Authors: Kirklin J W , Bargeron L M , Pacifico A D
Published: June 2012

Four patients with tetralogy of Fallot, three of whom had congenital pulmonary atresia, were treated by initial palliative operations to enlarge left and right pulmonary arteries which were considered too small for complete repair. Two to four years later the right and left pulmonary arteries had enlarged sufficiently to allow complete repair.
Entrainment and interruption of atrial flutter with atrial pacing: studies in man following open heart surgery.
Authors: Waldo A L , MacLean W A , Karp R B , Kouchoukos N T , James T N
Published: June 2012

To examine the question of why the pacing rate and duration of atrial pacing are crucial factors in the successful interruption of atrial flutter, studies were performed on 30 patients in the period following open heart surgery. In each patient the diagnosis of atrial flutter was made using a pair of wire electrodes placed on the right atrial epicardium at the time of operation and brought out through the anterior chest wall. The same electrodes were used for atrial pacing. Pacing faster than the spontaneous rate of the atrial flutter which failed to interrupt the atrial flutter was associated with transient entrainment of the atrial flutter up to the atrial pacing rate. Atrial flutter was interrupted successfully when the atria were paced at a rate which was too fast for the atrial flutter to follow. This was heralded by the conversion of previously negative flutter waves to positive atrial complexes in ECG lead II. When pacing the atria at a constant rate, 2-22 seconds with a mean of 10 seconds were required to interrupt the atrial flutter.
Prognostic efficacy of early clinical categorization of myocardial infarction patients.
Authors: Pozen M W , Stechmiller J K , Voigt G C
Published: June 2012

To assess the prognostic validity of "low risk" classification at 24-36 hours as the basis for early transfer to an intermediate coronary care unit, Killip and Hutter/Sidel criteria for risk classicication were applied to 410 patients with acute myocardial infarction (MI) and prospectively compared with respect to mortality and morbidity. Six percent of "low risk" patients by the Killip classification subsequently died and were therefore misclassified. No patients in the group classified as "low risk" by the Hutter/Sidel criteria died; however, more than two and a half times as many potentially "low risk" patients were excluded from this group. With respect to morbidity, 35 of 87 patients (40%) classified as "low risk" by Hutter/Sidel criteria developed 43 major complications during their hospitalization. Nine of these patients developed 11 of the 43 complications (26%) on day six or later, and for five of these patients, this was their first major complication during hospitalization. This significant incidence of morbidity in "low risk" patients, despite their low mortality rates as a group, must be taken into account in developing intermediate coronary care units.
Urinary kallikrein in normal renin essential hypertension.
Authors: Lawton W J , Fitz A E
Published: June 2012

The relationship between urinary kallikrein, urinary aldosterone, and plasma renin activity (PRA) was studied in hypertensive patients and normal subjects. Kallikrein was measured by a radiochemical esterolytic assay. Nine white males with normal renin, mild essential hypertension (25 +/- 5 [SD] yr; blood pressure [BP] 143 +/- 7 / 95 +/- 5 mm Hg) and six white normal males (23 +/- 3 yr; BP 115 +/- 15 / 70 +/- 6 mm Hg) were placed on a one-week diet consisting of 400 mEq Na+, 80 mEq K+ diet and a one week diet of a 10 mEq Na+, 80 mEq K+ diet. During salt restriction, PRA, urinary aldosterone, and urinary kallikrein progressively rose. (Urinary kallikrein on day 7: normals 18.3 +/- 13.7 esterase units [EU] per 24 hr; hypertensives 22.7 +/- 12.5 EU/24 hrs). There were no significant differences between the normals and hypertensives in PRA, aldosterone, or kallikrein excretion. After sodium balance was achieved, during salt loading, the PRA, aldosterone and kallikrein values were similar in both normals and hypertensives. (Urinary kallikrein on day 7: normals 5.0 +/- 5.2; hypertensives 7.9 +/- 4.4 EU/24 hrs.) Abnormalities in urinary kallikrein in hypertensives were not found when young white males with normal renin essential hypertension were compared to age-matched white male normal subjects. PRA appears related to urinary kallikrein excretion in this type of patient.
Discrete membranous subaortic stenosis. Report of 31 patients, review of the literature, and delineation of management.
Authors: Katz N M , Buckley M J , Liberthson R R
Published: June 2012

The presentation, management, and follow-up of 31 patients with discrete membranous subaortic stenosis (DMSS) is presented. DMSS comprised 16% of 185 patients with congenital left ventricular (LV) obstruction. Only one patient was older than 40 years. The rarity of DMSS in older patients in both our population and in the literature is noted, and possible explanations are discussed. One-quarter of these patients had dyspnea, chest pain, or syncope combined with electrocardiographic left ventricular hypertrophy (LVH) and strain, and these all had peak LV outflow gradients (PSG) greater than 85 mm Hg. One-quarter had neither symptoms nor electrocardiographic abnormalities and all had PSG less than 90 mm Hg. Bacterial endocarditis was found in 13%, and in 13% an immediate family member also had congenital LV obstruction. Following surgical resection (25 patients), 18 were asymptomatic, two had residual fibromuscular obstruction, and four developed new fibromuscular obstruction after from one to six years (leading in one to late sudden death). Thus, even after resection, these patients require continued re-evaluation for residual or new LV obstruction.
Familial congenital complete heart block and maternal systemic lupus erythematosis.
Authors: Winkler R B , Nora A H , Nora J J
Published: June 2012

A family is reported in which two siblings had congenital complete heart block with resultant congestive heart failure, the father and paternal grandfather show adult-onset conduction defects, and the mother has systemic lupus erythematosis. The interaction of heredity and environment is discussed in this context. A review of the literature on familial complete heart block suggests that so-called pure congenital-onset familial heart block, originally felt to be genetic, may in fact have an important enivronmental component, specifically related to ongoing maternal factors such as systemic lupus erythematosis.
Estimation of stroke volume changes by ultrasonic doppler.
Authors: Colocousis J S , Huntsman L L , Curreri P W
Published: June 2012

The purpose of this study was to conduct a controlled evaluation of the continuous-wave Doppler technique for the estimation of stroke volume changes. Six anesthetized dogs were studied. Aortic blood velocity was recorded from the suprasternal notch by a special continuous-wave Doppler unit. Cardiac output was varied by fluid infusion and exsanguination, and over 300 simultaneous records of aortic blood velocity and thermodilution cardiac output were taken. Average stroke volume and average systolic velocity integral (SVI), the area under the Doppler velocity curve were calculated. The relationship of SVI to stroke volume was evaluated for each animal using linear regression. Average results were: correlation coefficient 0.95 +/- 0.04 SD; y-intercept 0.38 +/- 0.14 cm(SD); standare error of fit 0.29 +/- 0.03 cm (SD). These data show that the systolic integral of aortic blood velocity was essentially directly proportional to stroke volume, even over a six-fold range. Thus, this technique will provide an accurate non-invasive estimate of changes in stroke volume.
Predictive implications of ventricular premature contractions associated with treadmill stress testing.
Authors: Udall J A , Ellestad M H
Published: June 2012

Follow-up data on future coronary events was collected on 6,500 patients who had undergone stress testing; 1,327 of these exhibited ventricular premature contractions (VPCs) associated with one or more phases of treadmill stress testing (TSTs). Eighty-three percent of all patients tested had known or suspected cardiovascular disease. The annual incidence of new coronary events (myocardial infarction, angina, cardiac death) during a five year follow-up was 1.7% among 1,067 patients without VPCs or ischemic ST changes, 6.4% in 758 patients with VPCs alone, 9.5% among 609 patients with ischemic ST changes alone and 11.4% in 569 patients with VPCs plus ischemic ST changes. The significance of VPCs associated with the TSTs rests largely upon the clinical status of the persons tested. VPCs observed among patients referred for TSTs for the evaluation of known or suspected cardiovascular disease, with or without ischemic ST abnormalities, represent a definite risk factor for future coronary events.
Natural history and classification of occlusive thromboaortopathy (Takayasu's disease).
Authors: Ishikawa K
Published: June 2012

Fifty-four Japanese patients with occlusive thromboaortopathy (OTAP), including four males, were classified according to evidence of complications attributed to OTAP at the time when the diagnosis was established: Group I, uncomplicated OTAP with or without the involvement of the pulmonary artery. Group II, mono-complicated OTAP: presence of a single complication together with uncomplicated OTAP. Group II was subdivided according to severity into group IIa - mild or moderate form, and group IIb - severe form. Group III, multi-complicated OTAP with two or more complications as well as uncomplicated OTAP. The five-year survival rate after established diagnosis was 83.1%. Seven patients died of OTAP within five years, but all had belonged to group IIb or III.
Alterations in ventricular mass and performance induced by exercise training in man evaluated by echocardiography.
Authors: DeMaria A N , Neumann A , Lee G , Fowler W , Mason D T
Published: June 2012

Few data are available regarding the effects of exercise training upon cardiac structure and performance in man. We evaluated the echograms of 24 normals before (PRE) and after (POST) 11 weeks of endurance exercise training. Conditioning consisted of a walk-jog-run protocol at 70% maximal heart rate for one hour four days per week. Training reduced heart rate and increased maximal duration and estimated oxygen consumption of treadmill exercise. Compared to PRE, the echogram in the POST training period revealed an increased left ventricular (LV) end-diastolic dimension (EdD), a decreased end-systolic dimension (EsD) and thus an increased stroke volume (EdD3-EsD3) and shortening fraction (EdD-EsD)/EdD). Cardiac output (CO) and peripheral vascular resistance (BP/CO X 80) were identical PRE and POST conditioning. Importantly, an increase in mean fiber shortening velocity was observed POST training as were increases in LV wall thickness, ECG voltage of S in V1 + R in V5, and LV mass. Thus endurance training was accompanied by increases in both LV dimension and mass as well as LV shortening fraction and contraction velocity as observed by echocardiogram.
Two-dimensional echocardiographic recognition of ruptured chordae tendineae.
Authors: Mintz G S , Kotler M N , Segal B L , Parry W R
Published: June 2012

Real-time, phased-array, two-dimensional echocardiographic studies identified ruptured chordae tendineae in five patients: four patients had a flail mitral valve and one had flail mitral and tricuspid valves. The characteristic abnormality was a rapid systolic motion of the involved leaflet beyond the line of valve closure into the atrium. The maximal abnormal systolic motion was greatest at the tip of the leaflet with a loss of the normal coaptation point. By contrast, the two-dimensional echocardiographic feature of mitral valve prolapse is an abnormal systolic motion that is maximal in the body of the leaflet with intact leaflet coaptation. Thus, two-dimensional echocardiography can identify flail mitral and tricuspid valves and is useful in distinguishing ruptured chorade from valvular prolapse.
Evaluation of left ventricular function (ejection fraction and segmental wall motion) by single pass radioisotope angiography.
Authors: Jengo J A , Mena I , Blaufuss A , Criley J M
Published: June 2012

Changes in ejection fraction (EF) and segmental wall motion (SWM) have been shown to be sensitive indicators of left ventricular (LV) function. This information is only obtainable by contrast angiography or gated blood pool scans. Gated studies assume a fixed geometry for the LV for EF determinations, are lengthy and limited primarily to the LAO projection. We correlated contrast and Tc-99m pertechnetate angiograms by singl pass radioisotope angiography (immediately preceding the contrast study) in 12 patients. EF was calculated from the LV time/activity curve and values ranged from .21 to .72. Angiographic correlation yielded r = 0.97. Regional LV wall motion was evaluated by dividing a summated cardiac cycle into 16 frames and dynamically and sequentially displaying these frames. Regional wall motion evaluation of four LV quadrants correlated well with angiography (r = 0.97). For quantitation these images were divided into four anterior and four inferior segments and the areas of respective segments were compared and expressed as a shortening fraction. SWM compared favorably with angiographic determinations (r ranged from 0.70 to 0.99). Thus, single pass radioisotopic determinations of EF and SWM in the RAO projection correlated well with the angiographic values and provide essential quantitative information of LV function otherwise unobtainable at the bedside.
Effect of nitroglycerin and arterial hypertension on myocardial blood flow following acute coronary artery occlusion in the dog.
Authors: Bache R J
Published: June 2012

This study was designed to evaluate the effects of nitroglycerin and phenylephrine-induced arterial hypertension on regional myocardial blood flow in awake dogs with acute occlusion of the left circumflex coronary artery. Myocardial blood flow to four transmural layers from epicardium to endocardium was estimated with 7-9 micron radionuclide labeled microspheres in 1) the non-ischemic myocardium, 2) the central ischemic zone, and 3) the border zone separating ischemic from normally perfused myocardium. Measurements were repeated 1) during infusion of nitroglycerin, 0.015 mg/kg/min, 2) during phenylephrine administered to increase arterial pressure 60 mm Hg above the control measurements, and 3) during combined nitroglycerin and phenylephrine administration. Both nitroglycerin and phenylephrine increased myocardial blood flow to the central ischemic area; nitroglycerin significantly decreased the resistance of the collateral vascular system, while the increased flow during phenylephrine administration was accounted for entirely by the increased arterial pressure with no change in collateral vascular resistance. The increased blood flow to the central ischemic zone during nitroglycerin administration was delivered preferentially to the subendocardium, while the increased blood flow during phenylephrine administration was directed exclusively to the subepicardium. Neither nitroglycerin nor phenylephrine significantly altered computed vascular resistance of the border zone, but because of the increased driving pressure, blood flow to the border zone was significantly increased during phenylephrine administration.
Changes in plasma catecholamines and dopamine beta-hydroxylase after corrective surgery for coarctation of the aorta.
Authors: Benedict C R , Grahame-Smith D G , Fisher A
Published: June 2012

In six patients within 12 hours of surgical correction of aortic coarctation there was a 750% increase in plasma noradrenaline concentrations accompanied by an increase in systolic and diastolic blood pressures. The magnitude of the postoperative increase in noradrenaline concentrations was related to the preoperative level of the pressure gradient across the coarctation. Six months after operation plasma noradrenaline concentrations were still significantly elevated. In nine patients who underwent other types of major surgery there was a small increase in plasma noradrenaline concentrations and a return to levels within the normal range within 24 hours. Various explanations for the rise in plasma noradrenaline concentrations are considered. In particular the possibility is raised that after surgical correction of aortic coarctation the increased levels indicate a marked increase in sympathetic nervous system activity; this may be mediated by baroreceptor mechanisms and may persist for up to six months after surgery.
Inexcitable right ventricle and bilateral bundle branch block in Uhl's disease.
Authors: Bharati S , Ciraulo D A , Bilitch M , Rosen K M , Lev M
Published: June 2012

A 29-year-old female with Uhl's anomaly developed complete atrioventricular (A-V) block. His bundle studies revealed block distal to the His bundle recording site with narrow QRS complexes. Right ventricular capture could not be obtained and despite successful left ventricular epicardial pacing, the patient died. Autopsy revealed absence of myocardium in most areas of the right ventricle and the right side of the ventricular septum with a normal tricuspid valve. Conduction system examination revelaed total destruction of both bundle branches. This is the first case where bilateral bundle branch block is shown to be present in Uhl's anomaly. Narrow QRS complexes probably reflected the absence of right ventricular forces.
Antiarrhythmic effects of aspirin during nonthrombotic coronary occlusion.
Authors: Moschos C B , Haider B , De La Cruz C , Lyons M M , Regan T J
Published: June 2012

To study the action of aspirin upon the myocardium per se, independent of thrombosis, coronary occlusion with a balloon catheter was induced in 53 anesthetized dogs divided into two groups. One group (N = 20) was treated daily with aspirin (600 mg/dog) for seven days and another (N = 33) was untreated. Left ventricular hemodynamics and precordial ECG mapping were used to assess the influence of myocardial ischemia over a four hour period. There were no significant differences in left ventricular function or extent of injury as judged by ECG mapping between the two groups. However, there was a significant decrease in the incidence of ventricular fibrillation in the treated dogs (5% vs 39%). Serial plasma samples for free fatty acid determination showed a significant rise in the untreated group. Aspirin blocked the FFA increment in the treated animals. Tissue samples from the ischemic area of left ventricle exhibited a significant reduction of the sodium and water increments, as well as a lesser potassium loss in the treated animals compared to the controls and may have been the basis for the lower incidence of arrhythmias. Since infusion of 51Cr labelled platelets showed no myocardial accumulation of platelets in either group, microthrombi did not appear to contribute to the observed differences.
Prognosis for patients with congenital heart disease and postoperative intraventricular conduction defects.
Authors: Krongrad E
Published: June 2012

Intraventricular conduction defects are common following repair of various forms of congenital heart disease. Such defects may affect adversely the long-term prognosis of patients in whom cardiac hemodynamics were adequately restored. Review of previously published studies suggests that the site of the conduction defect may be the reason for the different prognoses reported for patients from different institutions. The so-called "trifascicular block" pattern which sometimes occurs following open heart surgery is probably due to a more extensive lesion to the branching and penetrating parts of the His bundle rather than additional injury to the posterior left bundle branch fibers. Transient complete heart block in the immediate postoperative period seems to be a predictor for late development of complete heart block or sudden death at least as powerful as right bundle branch block and left anterior hemiblock.
Comparison of the electrocardiographic changes induced by maximam exercise testing with treadmill and cycle ergometer.
Authors: Wicks J R , Sutton J R , Oldridge N B , Jones N L
Published: June 2012

Maximum exercise testing using treadmill walking and cycle ergometry was compared in 40 male patients who had suffered a myocardial infarction in the preceeding twelve months. Maximum oxygen uptake was on average 17% greater in the treadmill than the cycle test and maximum heart rate was also higher, but the rate pressure product (RPP) was a similar due to a higher blood pressure in the cycle ergometer test. Eleven subjects showe ST-segment depression greater than 1 min and eight subjects showed ST-segment elevation greater than 1 mm. There was a close relationship (r2 = 0.96) between the magnitude of ST-segment changes in the two tests. Four subjects showing ST depression of 1 mm in the treadmill test showed depression during the cycle ergometer test which was less than this conventionally "positive" value. In these subjects RPP was lower during cycling than in treadmill walking. With both tests maximum ST-segment changes were measured immediately on stopping exercise: resolution of ST depression was more rapid than ST elevation. The two exercise testing modes are closely comparable in their ability to reveal changes of myocardial ischemia.
Impairment of antipyrine clearance in humans by propranolol.
Authors: Greenblatt D J , Franke K , Huffman D H
Published: June 2012

The effect of propranolol on antipyrine clearance in humans was evaluated in six healthy volunteers who received single 1.4 to 1.5 g doses of intravenous antipyrine on two occasions. The first (control) antipyrine trial was without concurrent drug administration; the second trial was done during treatment with therapeutic doses of propranolol (40 mg every 4 to 6 hours). Antipyrine elimination half-life (t1/2), volume of distribution (Vd), and total clearance were determined after each trial. In all subjects isoproterenol sensitivity decreased markedly during propranolol treatment, indicating a high degree of beta blockade produced by the drug. Mean antipyrine t1/2 during the propranolol treatment period was significantly prolonged, and total clearance significantly reduced, over the control values. Twenty-four-hour urinary excretion of 4-hydroxyantipyrine, the major metabolite of antipyrine, likewise was reduced from 23.6% of the dose on the control trial to 14.8% of the dose during propranolol coadministration (0.1 less than P less than 0.2). Vd however, was nearly identical during both trials (0.62 L/kg). Thus propranolol prolongs the half-life and reduces the clearance or biotransformation rate of antipyrine, a drug whose clearance is independent of hepatic blood flow. Propranolol may influence the activity of hepatic microsomal enzymes responsible for drug hydroxylation.
Diastolic left ventricular pressure-volume and stress-strain relations in patients with valvular aortic stenosis and left ventricular hypertrophy.
Authors: Peterson K L , Tsuji J , Johnson A , DiDonna J , LeWinter M
Published: June 2012

Left ventricular (LV) chamber and myocardial stiffness were determined in 17 patients, four subjects with normal LV function and 13 subjects with valvular aortic stenosis and concentric myocardial hypertrophy, using simultaneous catheter micromanometry and LV cineangiography. Pressure (P), volume (V), and wall thickness (h) were measured. Variability in both chamber and myocardial stiffness parameters was found with five of the aortic stenosis patients (Group 1, left ventricular end-diastolic pressure = 15 +/- 2 (SEM) mm Hg) exhibiting normal values for end-diastolic dP/dV and dP/dV/V, for chamber stiffness constants (a,a') derived from P-V and normalized P-V relations, respectively, for end-diastolic myocardial elastic stiffness (ES or EE, where S = spherical model and E = ellipsoidal model) at the midwall of the minor axis circumference, and for the myocardial stiffness constants (KS or KE) of the circumferential stress-strain relation. Eight other patients with aortic stenosis (Group II, left ventricular end-diastolic pressure = 20 +/- 3 (SEM) mm Hg) exhibited significant increases in end-diastolic dP/dV,dP/dV/V,ES and EE and a tendency for increase in the chamber stiffness constants (a,a') and myocardial stiffness constants (KS, KE). These observations suggest that concentric increase in muscle mass (increase in wall thickness/minor axis radius ratio and wall volume/chamber volume ratio) is an important determinant of elevated mid- and late diastolic pressures in patients with valvular aortic stenosis, while concurrently mitigating increases in both systolic and diastolic wall stress. In some patients with aortic stenosis, however, diastolic filling pressures are elevated more severely, not only as a result of concentric hypertrophy, but also in response to augmented muscle stiffness. Reversibility of increased ventricular diastolic stiffness and elevated filling pressures was documented as concentric hypertrophy regressed post-aortic valve replacement in one patient, suggesting that fibrosis is not invariably the cause of enhanced myocardial stiffness in this secondary and compensatory form of hypertrophy.