bluuebunny/crossref_metadata_2025 huggingface dataset:
Left ventricular outflow tract obstruction due to systolic anterior motion of the anterior mitral leaflet in patients with concentric left ventricular hypertrophy.
Authors: Maron B J , Gottdiener J S , Roberts W C , Henry W L , Savage D D , Epstein S E
Published: June 2012

Patients with hypertrophic cardiomyopathy (i.e., asymmetric septal hypertrophy) may show obstruction to left ventricular outflow under basal conditions or with provocative maneuvers. The presence of dynamic left ventricular outflow tract obstruction in patients with concentric ventricular wall thickening (but without abnormalities of the aortic valve) has been less well appreciated. Clinical and morphologic features of five patients with nondilated left ventricles and with left ventricular outflow obstruction are presented. In each patient peak systolic pressure gradients between left ventricle and systematic artery were measured at cardiac catheterization and ranged from 60-140 mm Hg under basal conditions or with provocation. Each patient had echocardiographically documented systolic anterior motion of the anterior mitral leaflet, which was apparently responsible for the outflow obstruction, and concentric left ventricular wall thickening (septal-free wall thickness ratio of less than 1.3). Two of the five patients had evidence of genetically transmitted hypertrophic cardiomyopathy, as evidenced by disorganized muscle cells in the ventricular septum or asymmetric septal hypertrophy in first degree relatives. Hence, left ventricular outflow tract obstruction associated with systolic anterior motion of the anterior mitral leaflet may occur in some patients with concentric left ventricular hypertrophy who do not have typical hypertrophic cardiomyopathy.
Repolarization abnormalities in survivors of out-of-hospital ventricular fibrillation.
Authors: Haynes R E , Hallstrom A P , Cobb L A
Published: June 2012

Survivors of out-of-hospital ventricular fibrillation (VF) are at high risk for recurrent VF, probably reflecting continued myocardial electrical instability. In this study 12-lead ECGs of 125 VF survivors with coronary heart disease were examined and compared to those of 98 ambulatory post-MI patients. The study was part of an effort to define clinical identifiers of patients likely to develop sudden cardiac death. Ventricular fibrillation survivors were commonly had premature ventricular complexes (PVCs):30% versus 13% (P less than 0.01). In addition, ECGs of VF survivors showed a significantly greater prevalence of ST-segment depression (46% versus 10%), T wave flattening (52% versus 26%), and QTc prolongation (35% versus 18%). It is proposed that these repolarization abnormalities represent asynchronous repolarization, which together with frequent PVCs, may set the stage for re-entrant ventricular dysrhythmias and ultimately VF. It is also possible that repolarization abnormalities together with premature ventricular contractions might serve as markers of patients with coronary heart disease who are at increased risk for sudden cardiac death.
The hemodynamic effects of intravenous tocainide in patients with heart disease.
Authors: Winkle R A , Anderson J L , Peters F , Meffin P J , Fowles R E , Harrison D C
Published: June 2012

In order to evaluate its hemodynamic actions, tocainide, a new orally effective antiarrhythmic drug, was given intravenously over a 15 minute period to 12 patients with compensated left ventricular dysfunction. Doses were 0.5 (4 patients) or 0.75 (8 patients) mg/kg/min. Hemodynamics and drug plasma concentrations were measured at the end and 15 minutes after the end of the infusion. Tocainide infusion produced small but statistically significant increases in the pulmonary and systemic vascular resistance, aortic and pulmonary arterial pressure, and left and right ventricular end-diastolic pressure. There was no significant change in left ventricular dp/dt, heart rate, or cardiac index. In patients with compensated left ventricular dysfunction, tocainide produces a small rise in vascular resistance and arterial pressure. Overall cardiac function is maintained with a small increase in left ventricular end-diastolic pressure.
Value and limitations of programmed electrical stimulation of the heart in the study and treatment of tachycardias.
Authors: Wellens H J
Published: June 2012

A review is given on the use of programmed electrical stimulation of the heart in patients suffering from tachycardia. The application of this technique makes it possible to evaluate mechanisms of tachycardia directly in the human heart. By repeating the same stimulation program following drug administration the effect of drugs on arrhythmia mechanisms can be studied. There are several factors, however, that influence the amount of information on mechanism and pathway of tachycardia and selection of appropriate therapy that can be obtained during the study. These factors as well as how information obtained programmed electrical stimulation of the heart has resulted in a better use of the 12-lead electrocardiogram as a diagnostic tool are discussed.
Vectorcardiographic quantification of infarct size in baboons.
Authors: Wickline S A , McNamara J J
Published: June 2012

A vectorcardiographic method has been developed for determining the absolute size of myocardial infarcts in baboons resulting from coronary artery ligation. Spatial area (mvolt . msec) and voltage (mvolt) difference-vectors were obtained for 8 animals by measuring the voltage loss and temporal deviation from pre- to post-ligation McFee scalar leads. The difference vectors were then correlated with the absolute infarct volumes, which were derived by histological assessment 10 days after ligation. Absolute lesion sizes ranged from approximately 2 cc to 14 cc, involving 10-30% of ventricular muscle mass. The correlation coefficient, r, for the area deviation index was 0.98 (SEE = +/- 0.24 cc); and for the voltage deviation index, r was 0.92 (SEE = +/- 0.51 cc). These results demonstrate that the severity of infarction can be accurately determined if prepathological vectorcardiograms are available.
Regional myocardial wall thickening response to nitroglycerin. A predictor of myocardial response to aortocoronary bypass surgery.
Authors: Chesebro J H , Ritman E L , Frye R L , Smith H C , Rutherford B D , Fulton R E , Pluth J R , Barnhorst D A
Published: June 2012

The peak rate of systolic wall thickening (p +/- dTw/dt) in regions of the left ventricle (LV) was determined preoperatively by biplane roentgen videometry in 18 patients before and after sublingual administration of nitroglycerin (NTG) and 3-23 months (median 12) after aortocoronary bypass surgery. The regional LV response to NTG was a reliable predictor for postoperative improvement in regional wall dynamics after successful aortocoronary bypass grafting. The ejection fraction response to NTG or surgery will not predict the regional myocardial response to NTG or surgery, nor will the regional response predict the global response. Subendocardial myocardial infarction is another cause of unimproved regional myocardial function after NTG and aortocoronary bypass surgery.
On the interpretation of the exercise test.
Authors: Selzer A , Cohn K
Published: June 2012

The widespread popularization of stress testing and the extensive application of its results in a variety of clinical settings make it imperative that a better method than the presently used simplistic "positive" or "negative" interpretation be devised. As a step toward a comprehensive diagnostic and prognostic index based on stress tests, a simple grading system of electrocardiographic changes, together with recognition of clinical modifiers, is suggested.
Cardiac tamponade: hemodynamic observations in man.
Authors: Reddy P S , Curtiss E I , O'Toole J D , Shaver J A
Published: June 2012

Hemodynamic studies were performed before and after pericardiocentesis in 19 patients with pericardial effusion. Right atrial pressure decreases significantly, from 16 +/- 4 mm Hg (mean +/- SD) to 7 +/- 5 mm Hg in 14 patients with cardiac tamponade. This change was accompanied by significant increases in cardiac output (3.87 +/- 1.77 to 7 +/- 2.2 l/min) and inspiratory systemic arterial pulse pressure (45 +/- 29 to 81 +/- 23 mm Hg). The remaining five patients did not demonstrate cardiac tamponade, as evidenced by lack of significant change in these hemodynamic parameters. In all patients with tamponade, right ventricular end-diastolic pressure (RVEDP) was elevated and equal to pericardial pressure; equilibration was uniformly absent in patients without tamponade. During gradual fluid withdrawal in the tamponade group, significant hemodynamic improvement was largely confined to the period when right ventricular filling pressure remained equilibrated with pericardial pressure. In 10 patients with tamponade and pulsus paradoxus, pulmonary arterial wedge pressure (PAW) was equal to pericardial pressure except during early inspiration and expiration when it was transiently less and greater, respectively; however, inspiratory right atrial pressure never fell below pericardial pressure. In these 10 patients, PAW decreased significantly following pericardiocentesis (P less than 0.001). In the remaining four patients with tamponade but without pulsus paradoxus, all of whom had chronic renal failure, PAW was consistently higher than pericardial pressure or RVEDP and did not decrease after pericardiocentesis. These data tend to confirm the hypothesis that in patients with tamponade, the venous pressure required to maintain any given cardiac volume is determined by pericardial rather than ventricular compliance. When pericardial compliance determines diastolic pressure in both ventricles, relative filling of the ventricles will be competitive and determined by their respective venous pressures (pulmonary vs systemic), which vary with respiration and alternately favor right and left ventricular filling. This results in pulsus paradoxus. However, if pulmonary arterial wedge pressure is markedly elevated before the onset of tamponade, as in patients with chronic renal failure, then pericardial compliance may only determine right ventricular filling pressure. In such cases, pulsus paradoxus may be absent.
Two-dimensional echocardiographic assessment of Ebstein's anomaly.
Authors: Ports T A , Silverman N H , Schiller N B
Published: June 2012

Nine patients with Ebstein's anomaly of the tricuspid valve were studied by two-dimensional echocardiography, using the standard long and short axis views as well as the apex four chamber view. With this latter view, the displacement of the tricuspid valve into the right ventricle was clearly seen in all nine cases of Ebstein's anomaly and was not noted in a control population. The severity of the tricuspid displacement was assessed by comparing the position of the mitral and tricuspid valves relative to the cardiac apex. The apex four chamber view allowed visualization of the atrioventricular (AV) ring simultaneously with the displaced tricuspid valve, and therefore the size of the "atrialized" right ventricle, true right ventricle and right atrium could be determined. These dimensions compared favorably with angiography.
Models of congenital heart disease in fetal lambs.
Authors: Fishman N H , Hof R B , Rudolph A M , Heymann M A
Published: June 2012

Intracardiac flow patterns were chronically altered by partially obstructing left ventricular (LV) inflow or outflow in midgestational fetal lambs. Physiological measurements of the fetal circulation were made serially through indwelling catheters and the use of radioactive microspheres. With LV inflow obstruction, mean LV output (LVO) decreased to 30% of control (P less than 0.01). Within seven days, the LV/right ventricular (RV) weight ratio decreased to 70% of control (P less than 0.01), and the mean LV/RV chamber volume decreased to less than one-half of control (P less than 0.001), simulating an early form of the hypoplastic left heart syndrome. With LV outflow obstruction, mean LVO decreased to 64% of control (P less than 0.05). Mean LV/RV wall thickness doubled (P less than 0.0001) and mean LF/RV chamber volume decreased to less than one-half of control (P less than 0.0001). Within four to ten days after increasing LV afterload, a large increase in LV mass occurred, which was demonstrated by morphometric analysis to be due to hyperplasia of ventricular myocytes. LV chamber volume decreased somewhat, simulating moderately severe congenital aortic stenosis. Over the long term (30--36 days), the mean LV/RV weight ratio decreased and the LV chamber was nearly obliterated, simulating very severe congenital aortic stenosis. The results suggest that by varying preload and afterload in both ventricles of the fetus, various forms of congenital heart disease may be simulated.
Effects of indomethacin on the vascular abnormalities of Bartter's syndrome.
Authors: Richards C J , Mark A L , Van Orden D E , Kaloyanides G J
Published: June 2012

We examined the hypothesis that the vascular abnormalities of Bartter's syndrome are due to excess production of prostaglandin. Balance studies and vascular reactivity studies were performed before and after indomethacin (200 mg/day) in a patient with well-documented Bartter's syndrome. During indomethacin, potassium balance became positive, serum potassium rose from 2.1--3 mEq/1 in the absence of potassium supplementation, plasma renin activity decreased from 55--3.2 ng/day and peripheral plasma PGA-like activity fell from 1460 +/- 220 to 456 +/- 71 pg/ml. Before indomethacin, forearm vasoconstrictor responses to brachial arterial infusions of angiotensin II, norepinephrine and to neurogenic reflex stimulation elicited by lower body suction were greatly depressed compared to those of normal subjects. During indomethacin these responses were restored to normal. The dose of intravenous angiotensin II required to increase diastolic blood pressure 20 mm Hg decreased from 160--30 ng/kg/min. These data support the hypothesis that the vascular insensitivity to exogenous angiotensin II, norepinephrine and to neurogenic reflex stimulation observed in this patient with Bartter's syndrome is due to excess prostaglandin. Moreover, stimulation of the renin-angiotensin-aldosterone system in this syndrome appears to be a compensatory adaptation to excess prostaglandin production.
Radiation exposure to the operator performing cardiac angiography with U-arm systems.
Authors: Balter S , Sones F M , Brancato R
Published: June 2012

We measured the radiation exposure received by a group of operators performing 700 coronary angiograms. All studies were performed using the brachial artery approach and the Philips Cardio Diagnost. Nineteen sites were monitored on each operator, using lithium fluoride thermoluminescent dosimeters. Four hundred examinations were performed with a table-mounted protective shield in place. Three hundred were performed without the shield. The average exposures (in mR per study) with and without the shield were 1.9/6 for the eyes and 1.4/8.3 for the thyroid. The resulting operator exposure with the shield in place is low enough so that an operator performing 25 procedures per week on a continuous basis will not exceed the recommendations of the National Commission on Radiological Protection and Units. We therefore strongly recommend the use of properly designed and appropriately positioned shield with all U-arm systems.
Disparate electrophysiological alterations accompanying dysrhythmia due to coronary occlusion and reperfusion in the cat.
Authors: Penkoske P A , Sobel B E , Corr P B
Published: June 2012

The electrophysiologic changes associated with dysrhythmias induced by coronary occlusion and by subsequent reperfusion were characterized with six complimentary approaches in chloralose-anesthetized cats (n = 57) with proximal occlusion of the left anterior descending (LAD) coronary artery. Occlusion led to reproducible ventricular dysrhythmia which abated in 35 minutes. The electrophysiologic effects of reperfusion initiated at this time could be studied. Simultaneous bipolar electrograms (epi-, myo- and endocardial) from ischemic and normal zones were analyzed by computer. Before the onset of the dysrhythmia induced by occlusion, conduction was markedly slowed, with dV/dt decreasing to 34% +/- 6% of control and conduction time (endo- to epicardial activation) prolonged to 328 +/- 77% of control. However, these values returned toward normal with reperfusion, even though it also consistently induced dysrhythmia. The idioventricular escape rate (determined by intense vagal stimulation) was 62 +/- 6 beats/min during the dysrhythmia induced by occlusion (equal to control), but increased during the reperfusion dysrhythmia to 188 +/- 12 beats/min. The occlusion dysrhythmia was exacerbated, but the reperfusion dysrhythmia was suppressed by rapid atrial pacing. The refractory period progressively shortened after occlusion and remained decreased during early reperfusion. Thus, increased conduction time through myocardial and epicardial regions, asynchronous depolarization and shortening of the refractory period accompanied dysrhythmia induced by occlusion. In contrast, the dysrhythmia induced by reperfusion was characterized by normal conduction time, through myocardial regions with continued significant epicardial delay, overdrive suppression, synchronous depolarization and a high idioventricular rate.
Recurrent sustained ventricular tachycardia 3. Role of the electrophysiologic study in selection of antiarrhythmic regimens.
Authors: Horowitz L N , Josephson M E , Farshidi A , Spielman S R , Michelson E L , Greenspan A M
Published: June 2012

Twenty patients with recurrent sustained ventricular tachycardia (VT) underwent serial electrophysiological studies (EPS) 1) to determine the predictive value of the EPS in the selection of antiarrhythmic therapy, and 2) to establish the therapeutic efficacy of available antiarrhythmic agents. In each patient VT could be reproducibly initiated by programmed stimulation. After control EPS, the effects of several drugs (lidocaine, procainamide, quinidine, disopyramide and diphenylhydantoin) on the ability to initiate VT were assessed. An oral regimen was chosen on the basis of acute EPS and its effectiveness was evaluated by repeat EPS in 24--72 hours. Blood levels achieved acutely were used as guidelines to chronic therapy. In 14 patients the initiation of VT was prevented by the acute administration of one or more agents. In 13 of these patients, a chronic oral regimen based on these results prevented recurrence of VT with a three- to 27-month follow-up. In the remaining patient, oral therapy could not achieve blood levels of procainamide shown to be effective intravenously, and VT recurred. In six patients no single drug or drug combination was effective during acute EPS, and VT recurred in all while on therapy with the agent shown to make initiation of VT most difficult. Procainamide prevented VT in nine patients; quinidine in three patients; lidocaine in three patients; diphenylhydantoin in two patients; and disopyramide in one patient. The mean duration of EPS studies was 4.5 days. This study suggests that serial EPS provides rapid identification of successful antiarrhythmic therapy and can predict in which patients conventional therapy would be ineffective, thereby identifying patients requiring more aggressive modes of therapy.
Effects of maximal exercise stress on left ventricular function in patients with coronary artery disease using first pass radionuclide angiocardiography: a rapid, noninvasive technique for determining ejection fraction and segmental wall motion.
Authors: Jengo J A , Oren V , Conant R , Brizendine M , Nelson T , Uszler J M , Mena I
Published: June 2012

Angiographically determined changes in segmental wall motion (SWM) and ejection fraction (EF) are sensitive indices of left ventricular (LV) function. To compare the effects of exercise on LV function, first pass radionuclide angiocardiography was used before and during maximal upright bicycle stress in patients with nonsignificantly stenosed coronary arteries, and in those with greater than 75% stenosis. Gamma camera acquisitions were made in the 30 degree RAO projection using a 20 mCi I.V. bolus of 99mTc-pertechnetate. In the control group (seven normals, one nonsignificant (CAD) the EF significantly increased between rest and exercise (0.65 +/- 0.03 to 0.81 +/- 0.03 (mean +/- SEM), p less than 0.005). In this group SWM measured over the two anterior and two inferoposterior segments uniformly increased. In the 11 patients with a history of angina and significant coronary artery obstruction, the EF did not change in three and significantly decreased in the remaining eight (0.57 +/- 0.04 to 0.45 +/- 0.03, p less than 0.005). In all 11 patients SWM either decreased or did not increase in the areas supplied by the significantly stenosed coronary arteries. Upright maximal stress angiocardiography appears to be well-suited for diagnosing ischemic heart disease and localizing the area of ischemic dysfunction.
Reduction of myocardial infarct size: comparison between left atrial and left ventricular bypass.
Authors: Pennock J L , Pae W E , Pierce W S , Waldhausen J A
Published: June 2012

A controlled study was undertaken to quantitate and compare the effect of left ventricular bypass (LVB) and left atrial bypass (LAB on left ventricular infarct volume (LVIV). After baseline studies, the left anterior descending coronary artery in each of 30 mongrel dogs was ligated 1-1.5 cm from its origin. After baseline ischemic studies, control dogs (group 1--10 dogs), LAB dogs (group 2--10 dogs), and LVB dogs (group 3--10 dogs) were monitored for four hours. Final infarct size was determined by the nitroblue tetrazolium staining technique. Heart rate, mean arterial pressure, and total systemic flow (TSF) showed no significant difference between control and left heart bypass groups. In group 1, the LVIV was 27.7 +/- 6.5 g/100 g left ventricle (LV). In group 2, left heart bypass (LHB) flow was 90 +/- 4% of TSF. The pressure time index (PTI) was 2845 +/- 52 mm Hg-sec/min. The PTI demonstrated no significant difference from cntrols. In group 2, LVIV was 22.5 +/- 6.0 g/100 g LV. LVIV was reduced 18.8% from controls (p less than 0.08). In group 2, LHB was complete. Left ventricular decompression (group 3) resulted in a PTI of 328 +/- 76 mm Hg-sec/min. The PTI was significantly different (p less than 0.001) from groups 1 and 2. The LVIV was 12.6 +/- 5.1 g/100 g LV. LVIV was reduced 54.5% from controls (p less than 0.001) and 44.0% from group 2 (p less than 0.001). These results suggest that LVB may be useful, not only in supporting the circulation in the patient with myocardial infarct and cardiogenic shock, but also in limiting infarct size.
Reaction of the myocardium to cryosurgery: electrophysiology and arrhythmogenic potential.
Authors: Klein G J , Harrison L , Ideker R F , Smith W M , Kasell J , Wallace A G , Gallagher J J
Published: June 2012

The acute and chronic electrophysiological effects of a cryolesion produced in the left ventricle were studied in six dogs. All dogs had frequent ventricular premature beats (VPB) and five of six dogs had ventricular tachycardia during the first 4 days after the cryolesion; only one of the six dogs continued to have VPBs after 1 week, and this dog had identical VPBs before the creation of the cryolesion. Neither control dog had VPBs. Two additional dogs underwent epicardial and transmural mapping studies immediately after production of a cryolesion. VPBs in these animals were shown to originate at the border of the cryolesion. Epicardial activation sequence during normal sinus rhythm was not altered by the chronic cryolesion. The border zone of the chronic cryolesion was sharply demarcated with normal potentials recorded outside of the lesion and "extrinsic" potentials recorded within.
An ultrasound Doppler technique for the noninvasive determination of the pressure gradient in the Björk-Shiley mitral valve.
Authors: Holen J , Simonsen S , Frøysaker T
Published: June 2012

The accuracy in determining the pressure gradient in the Björk-Shiley mitral implant from noninvasive ultrasound Doppler data was explored in nine adult patients. Manometric and ultrasound data were collectd simultaneously, and identical diastolic periods were used to compare the manometric gradient (delta Pm) with the gradient obtained from ultrasound data (delta Pu). In the nine patients the mean diastolic value of delta Pm ranged from 2-12.5 mm Hg and the difference between the mean diastolic values of delta Pm and delta Pu was 0.3 +/- 1.0 mm Hg(SD). The results of the investigation indicated that the method is accurate and reliable in the nonivasive determination of the mean diastolic gradient in the Björk-Shiley mitral implant.
Recurrent sustained ventricular tachycardia. 4. Pleomorphism.
Authors: Josephson M E , Horowitz L N , Farshidi A , Spielman S R , Michelson E L , Greenspan A M
Published: June 2012

Two or more morphologically distinct ventricular tachycardias were observed during electrophysiologic study in 14 patients with chronic sustained ventricular tachycardia. Nine of these patients had clinical ventricular tachycardia with multiple morphologies. During the study 13 patients manifested both right bundle branch block (RBBB) and left bundle branch block (LBBB) morphologies. The remaining patient had RBBB with both right and left axis deviation. Changing morphologies were observed spontaneously in four patients and could be produced in all 14 by ventricular stimulation. In 12 patients both RBBB and LBBB originated in the left ventricle, and in 11 of these patients, from within a left ventricular aneurysm. Diastolic fragmented activity representing reentry was unchanged during both morphologies in four patients and during one morphology in five patients. Epicardial mapping confirmed the aneurysm as the site of origin of multiform ventricular tachycardias in two patients. Our data suggest that 1) ventricular tachycardia is frequently pleomorphic; 2) multiple morphologies usually represent variable exit sites and/or ventricular activation during the same tachycardia; and 3) there is a frequent association of pleomorphic ventricular tachycardia with left ventricle aneurysm.
Neurogenic skeletal myopathy in patients with primary cardiomyopathy.
Authors: Darsee J R , Nutter D O , Hopkins L C , Heymsfield S B
Published: June 2012

Eleven patients with hypertrophic obstructive cardiomyopathy and eight patients with idiopathic congestive cardiomyopathy underwent extensive neuromuscular studies to determine if a skeletal myopathy is associated with uncomplicated primary cardiomyopathy. The clinical examination revealed peripheral neuropathies in six patients, but no evidence of muscle weakness or atrophy. Nerve conduction studies demonstrated a neuropathy in five of these six and in one other patient: three were in the hypertrophic group and three in the congestive group. Seven patients had abnormal electromyography, but none had characteristic myopathic changes. Of these seven patients, muscle biopsies showed denervation in two patients in the congestive group and type II atrophy in two patients in the hypertrophic group. We found no evidence of primary skeletal muscle involvement; however, neuropathic features and biopsy changes of denervation were present in both groups.
Coronary artery spasm during exercise in patients with variant angina.
Authors: Waters D D , Chaitman B R , Dupras G , Théroux P , Mizgala H F
Published: June 2012

Seven patients with typical variant angina without coronary stenoses greater than 50% developed angina and ST-segment elevation during treadmill exercise testing. In all cases the ST-segment elevation occurred in the same leads during exercise testing as during spontaneous attacks at rest. Five of the patients had developed spontaneous coronary spasm during coronary arteriography, in each case in the artery corresponding to the site of ST-segment elevation. In five patients, thallium was injected during the exercise test during which angina and ST-segment elevation occurred. In each case, a large perfusion defect not present at rest was found in the zone corresponding to the site of ST-segment elevation. These findings suggest that coronary artery spasm may occur during exercise in patients with variant angina.
Prevalence of mitral valve prolapse in presumably healthy young men.
Authors: Darsee J R , Mikolich J R , Nicoloff N B , Lesser L E
Published: June 2012

We determined the prevalence of mitral valve prolapse (MVP) in presumably healthy young men by studying 107 male house officers and medical students with cardiac auscultation in the supine, sitting and standing positions. Echocardiograms were performed at rest in the supine position before and after amyl nitrite inhalation and were obtainable in 101 subjects. Eleven of the 101 subjects had abnormal findings on auscultation: four had an isolated click and seven had a click and late systolic murmur. Correlation of the independent auscultatory and echocardiographic data in the 101 subjects showed that all seven of the subjects with a click and a murmur had echocardiographic evidence of prolapse. None of the 90 subjects with normal auscultation or the four with an isolated click had an abnormal echocardiogram. All seven subjects with MVP had thoracic skeletal abnormalities, but only one was symptomatic. These data suggest that the prevalence of MVP in healthy young males is similar to the reported 6-10% prevalence in healthy young females.
Comparative assessment of stimuli that release neuronal and adrenomedullary catecholamines in man.
Authors: Robertson D , Johnson G A , Robertson R M , Nies A S , Shand D G , Oates J A
Published: June 2012

We assessed the release of neuronal and adrenomedullary catecholamines in response to various stimuli of the sympathetic nervous system in normal subjects. Plasma catecholamines and their urinary metabolites, normetanephrine and metanephrine, were measured. Sodium restriction increased supine plasma norepinephrine by 37% and ambulatory plasma norepinephrine by 22%, with urinary normetanephrine excretion increased 29%. The sodium restriction did not elevate plasma epinephrine or urinary metanephrine. The most potent stimuli of norepinephrine were treadmill exercise, orthostasis, caffeine, the cold pressor test, sodium restriction and handgrip exercise, in descending order. Plasma epinephrine was increased by caffeine, treadmill exercise, the cold pressor test, handgrip exercise and the Valsalva maneuver, in that order. Syncope resulted in profound changes in plasma epinephrine but only modest changes in plasma norepinephrine. We conclude that in man, there is frequent dissociation between the effects of different stimuli on neuronal and adrenomedullary catecholamine release.
Prospective evaluation of intrahisian conduction delay.
Authors: McAnulty J H , Murphy E , Rahimtoola S H
Published: June 2012

We prospectively evaluated 46 patients who had intrahisian conduction delay. Twenty-three had a split His potential and 23 had a prolonged HV interval with a normal QRS complex. In those with a split His, the interval between the two His potentials averaged 32.7 msec (range 9--90 msec); in nine patients this split His was demonstrated only by atrial pacing. The 20 patients from this group with 1:1 atrioventricular conduction have been followed for an average of 18.1 months (range 2--48 months). All are alive. Three have had syncope, but Holter monitoring revealed no bradyarrhythmias. In the 23 patients with a narrow QRS and prolonged HV interval, the HV interval averaged 73.7 msec (range 57--180 msec). Twelve of these patients received pacemakers at the time of the His bundle study, six had symptomatic atrioventricular block and five had symptomatic sinus pauses. The 11 patients who did not receive pacemakers have been followed for an average of 15.1 months (range 2--44 months). In three with recurrent syncope and five with dizziness, monitoring has revealed no bradyarrhythmias. One patient died from a myocardial infarction without arrhythmias. Further prospective evaluation of patients with intrahisian conduction delay without documented bradyarrhythmias is needed, but with follow-up averaging 17 months and up to 4 years, patients with intrahisian conduction delay and without documented bradyarrhythmias appear not to require prophylactic permanent pacemakers to decrease morbidity or mortality.
Thrombo-embolism in Acute and in Healed Myocardial Infarction
Authors: JORDAN ROBERT A. , MILLER R. DREW , EDWARDS JESSE E. , PARKER ROBERT L.
Published: June 2012

This is a study of the location and incidence of intracardiac thrombi in acute and in healed myocardial infarction. In myocardial infarction intracardiac thrombi occur predominantly in the left ventricle. Anterior myocardial infarcts are more commonly associated with mural thrombi than posterior myocardial infarcts. Large myocardial infarcts and congestive failure are factors which predispose to the formation of left ventricular mural thrombi in myocardial infarction.
Patent Ductus Arteriosus in the Absence of a Continuous Murmur
Authors: DAMMANN J. FRANCIS , SELL C. GORDON R.
Published: June 2012

The diagnosis of patent ductus arteriosus is difficult when the classic continuous murmur is not present. In infancy, in the presence of cardiac decompensation and when the ductus approximates the aorta in size, the continuous murmur is frequently absent. A correct diagnosis may be important, however, for a large patent ductus arteriosus can cause serious difficulty. Early surgical treatment may be lifesaving. In this series a large patent ductus was associated with pulmonary hypertension, great cardiac enlargement and absence of the continuous murmur. The presence of pulmonary hypertension is further reason for early surgical treatment.
Studies of Electrocardiographic Changes during Exercise (Modified Double Two-Step Test)
Authors: YU PAUL N. G. , SOFFER ALFRED
Published: June 2012

A method of recording electrocardiograms
during
the performance of a double two-step exercise test is described. Data obtained from 32 normal subjects and 54 patients are analyzed, and changes in heart rate, S-T segment, T wave and Q-T interval and the occurrence of premature beats described. Criteria for an abnormal response indicating coronary insufficiency are defined. This method retains the merits of Master's original test and in addition has several distinct advantages.
Results of the Surgical Treatment for Mitral Stenosis
Authors: JANTON O. HENRY , GLOVER ROBERT P. , O'NEILL THOMAS J. E. , GREGORY JOHN E. , FROIO GREGORY F.
Published: June 2012

An analysis of the first 100 consecutive cases of mitral stenosis treated by commissurotomy is presented. Frank hemoptysis was noted in 25 individuals and systemic arterial emboli in 22 others; no recurrence of these complications was found one to three and one-half years after surgery. "Pure" mitral stenosis was present in 64, and an associated insufficiency in 27; in nine others there was an associated aortic insufficiency. A sinus rhythm changed to auricular fibrillation after surgery in 15; in nine the change was permanent. In one instance auricular fibrillation changed to sinus rhythm postoperatively. A rough correlation was found between the extremes of pulmonary artery systolic pressure and the clinical, roentgen and electrocardiographic findings Calcium was found in the mitral valves in 52 patients and did not, per se, predicate a poor functional result. No instance of rheumatic fever occurred postoperatively, even though 14 of 78 biopsied auricular appendages indicated rheumatic infection. Functional improvement occurred in 78 patients, and there were nine unimproved. There were 11 deaths due to surgery and two who died during this three-year follow-up from intercurrent infection.
A Comparative Evaluation of Tromexan and Dicumarol in the Treatment of Thromboembolic Conditions—Based on Experience with 514 Patients
Authors: SCARRONE LOUIS A. , BECK DOROTHY FAHS , WRIGHT IRVING S.
Published: June 2012

An evaluation of the comparative actions of Tromexan and dicumarol is herein reported. Five hundred fourteen patients were studied; a total experience of 6,642 days of Tromexan therapy and 5,006 days of dicumarol therapy were reviewed and analyzed. Previous reports of the more rapid initial prolongation of the prothrombin times and more rapid return to normal following cessation of therapy with Tromexan were confirmed. During adequate therapy the protection against thromboembolism was approximately equal for the two drugs. In other respects and with minor variations Tromexan and dicumarol were found to be quite comparable. The general advantages of anticoagulant therapy in the prevention of deaths and thromboembolic complications in myocardial infarction were comfirmed.
The Effects of Vasomotor Drugs and of Anemia upon Interarterial Coronary Anastomoses
Authors: ZOLL PAUL M. , NORMAN LEONA R. , CASSIN SIDNEY
Published: June 2012

The development of functionally significant interarterial coronary anastomoses was measured in 349 young domestic pigs by injecting the coronary arteries with the lead-agar mass of Schlesinger. By this technic well-developed anastomoses were absent in 132 normal control animals. Among the agents tested, acute coronary artery narrowing, sodium nitrite and anemia were effective in stimulating anastomoses. Anastomoses first began to appear two days after narrowing; they became larger and more frequent after seven days.
Dynamic aspects of acute mitral regurgitation: effects of ventricular volume, pressure and contractility on the effective regurgitant orifice area.
Authors: Yoran C , Yellin E L , Becker R M , Gabbay S , Frater R W , Sonnenblick E H
Published: June 2012

The dynamics of acute mitral regurgitation were studied in six open-chest dogs in whom a portion of the anterior leaflet was excised. Phasic mitral and aortic flows were measured electromagnetically and left ventricular filling volume, regurgitant volume (RV) and forward stroke volume (SV) were calculated. The systolic pressure gradient (SPG) between the left ventricle (LV) and left atrium (LA) was obtained from high-fidelity pressure transducers. The effective mitral regurgitant orifice area (MRA) was calculated from the hydraulic equation of Gorlin. Volume infusion resulted in significant increases in both left atrial and left ventricular pressures; thus, the SPG was unchanged and the increase in RV was due primarily to the increase in MRA. Angiotensin infused to raise arterial pressure resulted in greater increments in left ventricular than left atrial pressure, so that SPG rose significantly. The increase in RV was due to increases in both MRA and SPG. Norepinephrine infusion increased systolic left ventricular pressure and SPG, while left ventricular end-diastolic pressure and left atrial pressure diminished. Despite a significant increase in SPG, RV did not increase, due to a substantial decrease in MRA. Thus, angiotensin and volume infusion induced a substantial increase in regurgitation due to the increase in MRA, while augmentation of contractility after norepinephrine infusion resulted in a decrease in regurgitation through reduction of MRA. These findings support the clinical view that maintaining a small LV with sustained myocardial contractility will reduce mitral regurgitation. Alternatively, left ventricular dilatation can enhance mitral regurgitation by increasing the effective regurgitant orifice independent of SPG.
Technetium-99m stannous pyrophosphate myocardial scintigraphy after cardiopulmonary resuscitation with cardioversion.
Authors: Davison R , Spies S M , Przybylek J , Hai H , Lesch M
Published: June 2012

Thirty consecutive patients underwent technetium-99m stannous pyrophosphate myocardial scintigraphy 48--72 hours after successful cardiopulmonary resuscitation and direct current cardioversion. Five patients with transmural myocardial infarctions by ECG and enzyme determinations were correctly identified by scintigraphy. Myocardial scans were positive in five of nine patients with nontransmural infarction. Of 16 patients without evidence of myocardial infarction, only two (13%) had false-positive myocardial scans. The overall accuracy of imaging in this series was 80%. We conclude that false-positive scans after cardiopulmonary resuscitation with electrical cardioversion are infrequent, and do not significantly detract from the value of myocardial scintigraphy in the diagnosis of myocardial infarction.
Accurate volume determination in the isolated ejecting canine left ventricle by two-dimensional echocardiography.
Authors: Eaton L W , Maughan W L , Shoukas A A , Weiss J L
Published: June 2012

Two-dimensional echocardiography can provide serial cross-sectional images of the left ventricular cavity. We examined whether such serial images from steady-state ejecting hearts would allow three-dimensional reconstruction and accurate volume estimation without major geometric assumptions. Cross-circulated, paced dog hearts were suspended in a blood-filled tank. Serial cross-sectional images were taken at 3-mm intervals along the vertical axis. Left ventricular cavity and muscle areas of each image were planimetered with a light-pen system and summated for volume: total volume = sigma (areas x 3 mm). Direct left ventricular volume was measured through the cardiac cycle with a volumetric chamber connected to a balloon in the ejecting left ventricle. In six hearts, 67 separate direct volume measurements (range 9.5--54.7 ml) from various points in the cardiac cycle were compared with the simultaneous echo volume measurements. By least squares linear regression, echo volume = 1.01 (direct volume) - 0.44 ml; r = 0.972, SEE = 2.93 ml. Provided accurate cross-sectional localization is available, these studies suggest that extremely accurate steady-state left ventricular volume can be determined noninvasively in the ejecting heart from multiple cross-sectional images.
Aortocoronary bypass surgery: a 7-year follow-up.
Authors: Cameron A , Kemp H G , Shimomura S , Santilli E , Green G E , Hutchinson J E , Mekhjian H A
Published: June 2012

Follow-up of 748 consecutive patients who underwent aortocoronary artery bypass grafts was obtained for 5 to 94 months (average, 59 months). Operative mortality of 2.5% did not vary with number of vessels bypassed. There was a linear 3.5% annual recurrence rate of angina, and average annual late infarction rate of 1.4%. The cumulative survival rates did not differ for the number of grafts performed or for men and women, but did differ for left main coronary stenosis and impaired ejection fractions. The late cumulative survival rates for the entire group approached those of the general U.S. population.
Early malfunction of transvenous pacemaker electrodes. A three-center study.
Authors: Parsonnet V , Bilitch M , Furman S , Fisher J D , Escher D J , Myers G , Cassady E
Published: June 2012

A 3-year study by three medical centers has revealed a 1-year electrode malfunction rate of 7.4%; most malfunctions occurred within the first 30 days. The incidence of unavoidable early malfunction (3.2%) fell within the 5% standards suggested by the committee report of the Inter-Society Committee on Heart Diseases. Incidences of obscure cause (3.2%) may be difficult to identify prospectively and may be, to a certain extent, unavoidable. The majority of the malfunctions (4.2%) showed specific clues that indicated that they were preventable. Successful repositioning was achieved on the first attempt in 80.6% of the cases with malfunction, and only 0.7% required ultimate myocardial electrode implantation. The principal clues to potentially unsatisfactory positioning included the presence of a large right ventricle with or without tricuspid insufficiency, current thresholds greater than 0.5 mA and ST-segment deviations on the intracardiac electrogram of less than 2 mV. Electrode malfunction may be more common with bipolar than with unipolar electrodes; but significant differences in the incidence of malfunction among different unipolar electrodes were observed. These data indicate that further developments in transvenous electrode design are warranted.
Visualization of the distance between perfusion and anoxia along an ischemic border.
Authors: Simson M B , Harden W , Barlow C , Harken A H
Published: June 2012

The distance between perfusion and anoxia was measured on the border of an experimental ischemic area in the rabbit heart. Reduced nicotinamide adenine dinucleotide (NADH) fluorescence photography was used to detect myocardial anoxia. Fluorescein angiography marked areas of myocardial perfusion. The hearts were isolated, perfused with a hemoglobin-free solution and performed no external work. In all hearts there was a narrow band between areas of perfusion and anoxia that measured 329 +/- 42 mu (mean +/- SD). The transition from minimal to full NADH fluorescence was abrupt, less than 80 mu. We conclude that the normoxic/anoxic transition is sharp, and the gap between perfusion and anoxia is narrow along an ischemic border in the isolated heart performing no external work. These data suggest that in the vivo working heart the gap between perfusion and anoxia would be even narrower.
Angiographic study of univentricular heart of right ventricular type.
Authors: Soto B , Bertranou E G , Bream P R , Souza A , Bargeron L M
Published: June 2012

An angiographic analysis of 10 cases of univentricular heart of the right ventricular type is reported. This congenital malformation is characterized by a large chamber with right ventricular morphology that receives both atrioventricular valves, and a second, smaller chamber, a trabecular pouch, with left ventricular morphology. These chambers are separated by a posterior septum but are connected by an inlet septal defect. The angiographic studies were done using the angled angiographic techniques in three patients and the standard frontal and lateral angiographic views in seven cases. The atrial situs in seven patients was solitus, in one inversus, and in two it was ambiguus with left isomerism. In seven patients the usually large right ventricular chamber received two atrioventricular valves and in four patients, one atrioventricular valve was straddling. Three patients had atresia of one atrioventricular valve. The trabecular pouch was small in seven patients but relatively large in three. In six patients the trabecular pouch was located posterior and to the left of the right ventricular chamber and in four anterior and to the right. Double outlet right ventricle was present in all cases. The aorta arose anteriorly to the pulmonary artery in nine patients and posteriorly in one. An autopsy was performed in one case and its correlation with the angiographic findings was remarkable. The angiographic demonstration of the anatomicaly details of this entity and its associated anomalies was facilitated by angled angiography.
The natural history of conduction system disease in myotonic muscular dystrophy as determined by serial electrophysiologic studies.
Authors: Prystowsky E N , Pritchett E L , Roses A D , Gallagher J
Published: June 2012

To evaluate the progression of conduction system disease in myotonic muscular dystrophy, nine patients underwent serial electrophysiologic studies at a mean of 35 months apart. At the initial study, seven patients had first-degree atrioventricular block and three of these seven had disease in the His-Purkinje system (HV greater than 55 msec). At the second study, seven patients had prolonged HV intervals, and during the almost 3-year period, HV intervals increased by at least 5 msec in all seven patients. No electrophysiologic or electrocardiographic measures could be found that correlated with progression of conduction disease in these patients. Because of the failure of electrophysiologic measures to predict progression of conduction disease in these patients, electrophysiologic studies are recommended only for symptomatic patients. If significant disease is found in either impulse formation or conduction, permanent pacemaker therapy is warranted.