bluuebunny/crossref_metadata_2025 huggingface dataset:
Retrograde Pre-excitation
Authors: NARULA ONKAR S.
Published: June 2012

The purpose of this report was to compare antegrade (atrioventricular [A-V]) and retrograde (ventriculoatrial [V-A]) conduction times in 124 consecutive patients who exhibited bidirectional conduction during diagnostic studies where His bundle recordings were obtained. None of these patients had any evidence of antegrade pre-excitation. The mean age was 64 ± 13 (range 32-89 years). The QRS complex was abnormal (≧ 0.11 sec) in 46 patients. The control mean P-R, A-H, and H-V times were 170 ± 37, 80 ± 21, 49 ± 8 msec, respectively. The A-V and V-A times were measured from local bipolar right ventricular (RV) and right atrial (RA) electrograms obtained via pacing catheters placed in the high RA and RV apex. Both RA and RV were paced at identical cycle lengths and the rate was progressively increased until block developed or to a cycle length of 400-330 msec. The V-A time was longer than A-V in 45 (group A), equal in 11 (group B), and shorter in 68 patients. Of the latter 68 patients (group C) in 49 V-A time was 172 ± 36 as compared to 197 ± 38 msec for A-V time, and while the interval lengthened at higher pacing rates, it remained shorter than A-V time throughout (197 ± 40 versus 261 ± 51 msec). In the remaining 19 patients (group D) the V-A was not only shorter than A-V (176 ± 27 versus 207 ± 49 msec) but remained unchanged up to the highest paced rates, whereas A-V time progressively lengthened 269 ± 81 msec). In group D a constant V-A time in all probability is indicative of retrograde impulse transmission through tissue other than the A-V node, i.e., bypass pathways functioning only in a retrograde direction. Progressively increasing A-V and V-A times in groups A to C suggest bidirectional conduction through a single common pathway. Our data demonstrate that: 1) V-A is less often longer (35%) and more often shorter (56%) than A-V; 2) In some patients retrograde pre-excitation and V-A may occur through bypass pathways, functional in the retrograde direction only. These findings may be of clinical significance.
The Pathophysiology of Malignant Ventricular Arrhythmias During Acute Myocardial Ischemia
Authors: WILLIAMS DAVID O. , SCHERLAG BENJAMIN J. , HOPE RONALD R. , EL-SHERIF NABIL , LAZZARA RALPH
Published: June 2012

In 20 anesthetized open-chest dogs, epicardial electrograms were recorded from ischemic and nonischemic zones of the left ventricle during acute occlusion of the left anterior descending artery. The average time to onset of ventricular tachycardia during atrial pacing (150-200 beats/min) was 4 min, 18 sec. In 18 dogs, ventricular ectopic beats were induced in normal and ischemic zones after every tenth atrial stimulus. Those induced in the ischemic zone consistently caused ventricular tachycardia earlier (mean: 3 min, 22 sec) than those in the normal zone (mean: 4 min, 11 sec) (
P
< 0.01). This arrhythmia, whether spontaneous or induced, always followed the complex which demonstrated the greatest delay of the ischemic zone potential and increased ventricular activation time. Ventricular tachycardia was repeatedly produced by ectopic beats with late diastolic coupling. Analysis of the episodes of tachycardia leading to fibrillation revealed a progressive increase in the ventricular activation time of the successive beats, whereas in those self-terminating episodes ventricular activation time progressively decreased. These data suggest that the major determinant of malignant ventricular arrhythmias in acute ischemia may be the related abnormalities of ventricular activation rather than the coupling of the premature ectopic beats.
Survival after Resuscitation from Out-of-Hospital Ventricular Fibrillation
Authors: BAUM ROBERT S. , ALVAREZ HERNAN , COBB LEONARD A.
Published: June 2012

During the first three years in operating a comprehensive system for the management of out-of-hospital medical emergencies, 146 patients were resuscitated from ventricular fibrillation, hospitalized, and discharged home. The diagnosis of acute transmural myocardial infarction associated with the episode of ventricular fibrillation was confirmed in only 17% of the patients. The presence of myocardial necrosis, based on either evidence of new transmural infarction or LDH-isoenzyme criteria was established in 49.5% of the patients. During the follow-up period, averaging 418 days, 43 of the 146 patients died. Thirty-four of the 43 deaths occurred suddenly outside the hospital. Patients whose aborted sudden cardiac death was associated with acute transmural infarction had a mortality rate of 14% after two years of follow-up. In contrast, patients without evidence of acute myocardial necrosis had a high mortality rate — 47% at two years.

It is concluded that: 1) out-of-hospital ventricular fibrillation is common and treatable; 2) the phenomenon of sudden cardiac death should not be equated with acute myocardial infarction; 3) patients resuscitated from ventricular fibrillation without associated acute myocardial infarction are prone to sudden death — most likely from ventricular fibrillation.
Differences in Antibody Response to Streptococcal Antigens in Children with Rheumatic and Non-rheumatic Mitral Valve Disease
Authors: SHULMAN STANFORD T. , AYOUB ELIA M. , VICTORICA BENJAMIN E. , GESSNER IRA H. , TAMER DOLORES F. , HERNANDEZ FRANCISCO A.
Published: June 2012

The usefulness of streptococcal antibody tests — anti-streptolysin O (ASO), anti-desoxyribonuclease B (anti-DNAse B), and anti-group A carbohydrate (A-antibody) — in differentiating rheumatic from non-rheumatic mitral disease was explored. Sera from 154 children with mitral disease were studied. Fifteen of 17 patients with chronic mitral insufficiency (MI) following acute rheumatic fever manifested persistence of elevated A-antibody levels following the decline of ASO and anti-DNAse B titers to normal 18-36 months after their acute illness. This antibody pattern was not observed among sera from 35 patients with congenital mitral valve deformities. Serologic study of 71 children with mitral disease of obscure etiology identified three groups: subgroup A includes those 12 who demonstrated the antibody pattern associated with rheumatic MI, while subgroup B is comprised of 39 children with normal A-antibody levels. Twenty patients (subgroup C) manifested evidence of recent streptococcal infection. These data suggest that the use of the A-antibody test in conjunction with other streptococcal antibody tests is of potential value in differentiating rheumatic from non-rheumatic mitral disease.
De Subitaneis Mortibus
Authors: JAMES THOMAS N. , PUECH PAUL
Published: June 2012

A twenty-two-year-old woman with type A Wolff-Parkinson-White syndrome had a long history of paroxysmal tachycardia and died of a stroke. Until the last two years of life the tachycardias responded to medical treatment, but thereafter they could only be terminated with electrical shock. During one such shock her sinus rhythm disappeared and for over a year she had only atrioventricular (A-V) junctional rhythm although paroxysms of tachycardia persisted.

Special studies of the heart after death included serial sections of the entire A-V ring. Nonspecific degenerative disease of both atria included the internodal pathways. Both the sinus node artery and the A-V node artery were narrowed by mural thickening. The sinus node was generally intact but virtually all atrionodal connections were degenerated. The A-V node was similarly detached from its atrial connections but was in direct continuity with the His bundle. The right bundle branch was interrupted at its origin. Within the central fibrous body there were numerous lacunae and one long cleft extending from atrial to ventricular septum parallel to the A-V node. Although the cleft contained cells, there was no direct A-V connection. At the right lateral A-V junction a long thin cylinder of Purkinje cells lay parallel to the tricuspid valve ring and connected to the atrium but not the ventricle. Beneath the left atrial appendage there was a fault in the mitral annulus through which there was a direct A-V connection. Most of this connection was composed of P cells and thus resembled the patient's own sinus node. The atrial connection was to Bachmann's bundle, which was extensively degenerated. The ventricular connection was to ordinary working myocardium midway between epicardium and endocardium. Some functional implications of these anatomical findings are discussed.
Analysis of re-entry mechanisms in the three patients with concealed Wolff-Parkinson-White syndrome.
Authors: Neuss H , Schlepper M , Thormann J
Published: June 2012

Three patients with recurring attacks of supraventricular tachycardia and no electrocardiographic evidence of the Wolff-Parkinson-White syndrome (WPW syndrome) were studied using intracardiac recordings and atrial stimulation. The findings are interpreted as evidence of a concealed WPW syndrome. In all patients there was antegrade block of the anomalous atrioventricular (A-V) pathway while retrograde conduction was unimpaired and allowed the initiation of the observed reciprocating tachycardias. The diagnosis was based on the assumption that the ventricular myocardium was an essential link in the re-entry circuit. The three most important findings to support this assumption are: 1) retrograde conduction time, measured by the Q-A' interval (Q in ECG to atrial echo), and the rate of tachycardia were dependent on the mode of intraventricular conduction: 2) the first Q-A' interval of the tachycardia was independent of the A-H interval (initiation of atrial impulse to first activation of the His bundle) of the initiating premature atrial depolarization (PAD); 3) there was retrograde conduction following a ventricular premature beat during tachycardia at a time when the A-V node and/or the bundle of His would be refractory.
Genesis of high frequency notching of QRS complexes in an in vivo cardiac model.
Authors: Vanderark C R , Reynolds E W
Published: June 2012

High frequency notching of the QRS complex is associated with transmural infarction, cardiomyopathies, and ventricular hypertrophy from any cause. The mechanism producing notching is unknown; but the presence of a discrete anatomic lesion is not an essential feature. The hypothesis that notching was produced by activation across, rather than along, myocardial fibers was investigated by stimulation at 12 points around a clock electrode attached to the epicardium while mapping isoschronous lines in the area activated. All fibers at the subendocardial layer beneath the clock electrode were ligated by a pursestring suture. Propagation direction, as measured by isoschronous maps, produced more notched QRS compleses when the path was across, rather than paralled with, the myocardial fibers. Using grouped data and a 5 times 6 table, notches versus the angle formed between fiber direction and orientation of the direction of travel were shown to be related (P less than 0.001). The hypothesis that cross-fiber activation enhances notching was confirmed. retrograde activation did not increase notching nor did ligation of subendocardial fibers.
Echocardiography of the tricuspid valve in congenital left ventricular-riht atrial communication.
Authors: Nanda N C , Gramiak R , Manning J A
Published: June 2012

Two patients, ages 14 and 18, with congenital left ventricular-right atrial communication through a defect in the tricuspid valve were studied by echocardiography. Proof was obtained by angiocardiography and surgery in one and ultrasonic contrast injection and angiocardiography in the other. Both presented clinically as uncomplicated ventricular septal defects. Echocardiography consistently demonstrated a high frequency, low amplitude flutter of the tricuspid valve in systole and none in diastole. Following surgical correction of the defect in one patient, there was complete disappearance of the systolic flutter. Systolic flutter has not been observed with tricuspid incompetence nor with other forms of ventricular septal defects. Fistulous communication from the aorta to the right atrium just above the tricuspid valve did not demonstrate systolic flutter in one patient studies. Tricuspid valve systolic flutter appears to be caused by the passage of the left ventricular jet blood into the right atrium through a defect in the tricuspid valve. Echocardiographic study of the tricuspid valve is of value in the recognition of the congenital left ventricular-right atrial communication.
Echographic determination of left ventricular volumes in pediatric patients.
Authors: Meyer R A , Stockert J , Kaplan S
Published: June 2012

The purpose of this study was to validate the accuracy of determining left ventricular (LV) volumes by echocardiography in infants and children. Thirty-one patients between the ages of two months and 15 years underwent left ventriculography (biplane antero-posterior and lateral cine). Ventricular volumes using an ellipsoidal model were calculated for end diastole from the cineangiograms. There was a strong correlation (r = 0.856) between the echographic minor dimension (Be) and the minor lateral cine dimension (Bc) at end diastole. A similar correlation (r = 0.889) existed between the LV volume in end diastole measured by cineangiography and Be. The correlation coefficient between the echo minor dimension and the lateral minor cine dimension in end systole was 0.753. A relation between ejection fraction (EF) and the echo minor dimension measurements in end diastole and end systole was formulated, which permitted estimation of the EF from the echo measurements. As a result of this study, it was concluded that the LV minor dimension can be measured reliably by echocardiography in children and from these measurements LV volumes, ejection fraction, and hence, stroke volume can be estimated.
Platelet survival time following aortic valve replacement.
Authors: Steele P , Weily H , Davies H , Ppppas G , Genton E
Published: June 2012

Thromboembolism continues to complicate the course of patients following aortic valve replacement. In patients with prosthetic and homograft mitral valves, platelet survival time has been shown to correlate with occurrence of thromboembolism. This study extends these observations to patients with aortic valve disease. Platelet survival time was measured (by the chromium-51 method) in 73 patients with aortic valve disease. Eighteen patients were studied preoperatively and had platelet survival times of 3.4 plus or minus 0.14 days (mean plus or minus standard error of the mean), almost the same as normal (3.7 plus or minus 0.4 days). Platelet survival time was shortened (P less than 0.001) following aortic valve replacement with Starr-Edwards prosthesis - Model 1000: 2.5 plus or minus 0.13 days (N = 6); Model 1200-1260: 3.0 plus or minus 0.10 (n = 14); model 2300-2320: 3.0 plus or minus 0.15 days (N = 9) - and with stented aortic homografts: 3.0 plus or minus 0.10 days (N = 16). Platelet survival time was normal following aortic valve replacement in patients with directly sewn aortic homografts 3.7 dats plus or minus 0.24 days (N = 10). Eleven patients with Starr-Edwards prostheses had a history of thromboembolism and all also showed shortened platelet survival time (2.7 plus or minus 0.12 days, P less than 0.001), a measurement which was significantly different (P less than 0.01) from the 18 patients with Starr-Edwards prostheses and no thromboembolism (3.0 plus or minus 0.09 days). Platelet suppressant therapy prolonged platelet survival in eight patients with Starr-Edwards devices, thromboembolism, and shortened platelet survival time. These results suggest that insertion of Starr-Edwards valves and stented aortic homografts alter platelet survival time but that direct homografts do not. A correlation between occurrence of thromboembolism after aortic valve replacement and shortened platelet survival time has been shown.
De subitaneis mortibus. X. Familial congential heart block.
Authors: James T N , McKone R C , Hudspeth A S
Published: June 2012

Complete heart block was found shortly after birth in a brother and sister (not twins). Both were treated by electronic pacing because of symptoms attributable to inadequate cardiac output and electrical instability of heart. The boy has done well with his artificial pacemaker and is now six years old. His sister died of complications due in part to the large size of her pacemaker and small size of her body. At necropsy special studies of her heart included the centers for normal impulse formation and concuction. The primary abnormalities were at the junction of atrial septum with atrioventricular (A-V) node, and at the origin of the two bundle branches from the His bundle. The A-V node was isolated by collagen at all its margins except its junction with the His bundle. The proximal His bundle was essentially normal, but from that point on through the initial protions of both the left and right bundle branches there was extensive caseous degeneration which interrupted any possible conduction. These findings are discussed in relation to fetal and postnatal development of the human A-V node, and the His bundle and its branches; and in the context of a recently observed mathematical relationship between sinus rate and two forms of experimentally produced A-V junctional escape rhythms.
Diastolic murmurs in the presence of Starr-Edwards mitral prosthesis.
Authors: Schaffer R A , McAnulty J H , Starr A , Rahimtoola S H
Published: June 2012

Diastolic murmurs associated with the Starr-Edwards mitral prosthesis have not been described previously. In this report, five patients with mitral prostheses are described in whom apical mid-diastolic and presystolic murmurs resulted from two different causes. Three patients had clots obstructing the prosthetic orifice. The other two had normally functioning protheses and moderately severe aortic insufficiency. The occurrence of mid-diastolic and presystolic murmurs in the presence of a normally functioning prosthetic mitral valve demonstrates that 1) the mid-diastolic Austin Flint murmur can occur in the absence of incomplete mitral valve opening, premature mitral valve closure, vibrating mitral leaflets, or relative mitral stenosis and 2) the presystolic Austin Flint murmur can occur in the absence of incomplete valve opening or presystolic mitral regurgitation. However, the presystolic murmur was associated with early closure movement of the presthetic poppet.
The omnicardiogram Study of a proposed method for detecting coronary heart disease in an asymptomatic population.
Authors: Nay P , Kannel W B , Castelli W P , McNamara P M
Published: June 2012

A proprietary, commercial technique has been proposed by its inventor as a noninvasive method of detecting subtle electrocardiogram abnormalities, not apparent by conventional means. To study the ability of the omnicardiogram to detect latent coronary heart disease in an asymptomatic population, 200 normal electrocardiograms from the Framingham Study cohort were analyzed by this technique. One-half of these consisted of the last normal electrocardiogram prior to development of clinical coronary heart disease. The omnicardiogram showed a higher degree of sensitivity than did the electrocardiogram to coronary heart disease, indicating an increased risk of myocardial infarction in this group. The low specificity of this technique as indicated by the large percentage of false positives shows that the omnicardiogram is not diagnostic of coronary heart disease in asymptomatic persons with normal electrocardiograms.
Echocardiographic features of subpulmonic obstruction in dextro-transposition of the great vessels.
Authors: Nanda N C , Gramiak R , Manning J A , Lipchik E O
Published: June 2012

Eleven patients with dextro-transposition of the great vessels (TGV) and subpulmonic (left ventriclar outflow) obstruction documented by cardiac catheterization and angiography were studied by echocardiography. Echocardiographic features were which characterized the outflow obstruction included a) prolonged diastolic apposition of the mitral valve with the ventricular septum (10 patients), b) smaller width of the pulmonary artery as compared to the aortic root (10 cases), and c) narrowing of the subpulmonic area demonstrated by beam anglation studies through the planes of the mitral valve and the pulmonary artery (five cases). In addition, four patients showed abnormal systolic anterior movements (SAMs) of the anterior mitral leaflet resembling those observed in idiopathic hypertrophic subaortic stenosis. The SAM'S WERE LARGE IN THREE PATIENTS AND MAY HAVE ACCENTUATED THE OUTFLOW OBSTRUCTION. Additional evidence for this was provided by the movement of the pulmonary valve towards closure with the onset of the mitral SAM'S. These features were uncommon or absent in a comparison group of 17 patients with TGV and no outflow obstruction. Echocardiography appears to be useful in the diagnosis of subpulmonic muscular obstruction in TGV. Demonstration of definite mitral SAM'S IN SOME PATIENTS SUGGEST THE PRESSENCE OF ASSOCIATED FUNCTIONAL OBSTRUCTION OF THE TYPE SEEN IN IDIOPATHIC HYPERTROPHIC SUBAORTIC STENOSIS.
Diastolic vibration of the interventricular septum in aortic insufficiency.
Authors: Cope G D , Kisslo J A , Johnson M L , Myers S
Published: June 2012

The echocardiograms of 46 patients with aortic insufficiency which manifested typical high frequency vibrations of the anterior mitral valve leaflet were reviewed. All patients had overt clinical evidence of aortic insufficiency which was confirmed by angiography in 17 cases. In 17 cases (eight of whom underwent catheterization and angiography), high frequency diastolic vibrations of the interventricular septum of similar frequency to those on the anterior mitral leaflet were observed. This finding was not seen in 100 control echocardiograms from patients without clinical evidence of aortic insufficiency, and represents a previously undescribed echocardiographic manifestation of this lesion.
Echocardiographic features of total anomalous pulmonary venous connection.
Authors: Paquet M , Gutgesell H
Published: June 2012

Seven patients, four months to ten years of age, with total anomalous pulmonary venous connection (TAPVC) were studied by echocardiography. The diagnosis was confirmed by cardiac catheterization, angiography, and surgery in each. The connection was to the left vertical vein in four patients, to the coronary sinus in one, to the inferior vena cava in one, and directly to the right atrium in one. All patients exhibited the echocardiographic criteria of right ventricular diastolic volume overload (RVDVO). In addition, an echo-free space was identified dorsal to the posterior wall of the left atrium. Indocyanine green dye studies done in one of the patients provided evidence that this echo-free space represents the common pulmonary venous chamber. The combination of echocardiographic evidence of RVDVO and demonstration of an echo-free space dorsal to the left atrium is strongly suggestive of TAPVC and should allow an early diagnosis in infants with this anomaly.
Precursors of sudden coronary death. Factors related to the incidence of sudden death.
Authors: Kannel W B , Doyle J T , McNamara P M , Quickenton P , Gordon T
Published: June 2012

Precursors of sudden death were sought in men--1838 civil servants in Albany, New York, and 2282 residents of Framingham, Massachusetts--under continuous surveillance for 16 years. In men 45-74 years old there were 234 deaths attributed to coronary heart disease (CHD) of which 109 occurred within one hour of onset of symptoms. More than half of all deaths due to CHD occurred outside the hospital and about 80 per cent of these were sudden. Most were unheralded by prior symptoms of CHD. Persons at high risk of death from CHD, including sudden death, can be identified long before the terminal unexpected catastrophe. The same precursive stigmata exist in persons subject ot coronary attacks whether or not immediately fatal. The risk of sudden death in these two populations was positively correlated with high blood pressure, the electrocardiographic pattern of left ventricular enlargement, obesity, and heavy cigarette usage. Sudden death is a common and possibly incidental expression of lethal coronary heart disease. The potential candidate for sudden death cannot be confidently distinguished from the individual who succumbs more slowly of myocardial infarction. The inescapable conclusion is that the prevention of sudden death requires the prevention of coronary attacks.
The effect of hypoglycemia on myocardial ischemic injury during acute experimental coronary artery occlusion.
Authors: Libby P , Maroko P R , Braunwald E
Published: June 2012

To determine the effect of hypoglycemia on myocardial ischemic injury following coronary artery occlusion epicardial electrograms were recorded 15 minutes after two 20-minute coronary artery occlusions in seven anesthetized dogs. The first occlusion was a control (blood glucose 85 plus or minus 5(sd) mg per cent). Before the second occlusion hypoglycemia was induced (blood glucose 40 plus or minus 5 mg per cent) by the intravenous administration of insulin (2 units/kg). The average ST-segment elevation in leads during control was 3.5 plus or minus 1.0 mV which rose to 6.1 plus or minus 1.4 mV during the second occlusion (P smaller than 0.05). The number of sites showing ST-segment elevation exceeding 2 mV increased from 7.6 plus or minus 1.6 during control to 10.6 plus or minus 1.4 (P smaller than 0.05) during the occlusion with hypoglycemia. In other dogs, a coronary artery was occluded for 24 hours. Epicardial ST-segment elevations were compared to creatine phosphokinase (CPK) activity and histological appearance from the same sites. CPK activity in sites with normal ST segments (0-2 mV) was 33.1 plus or minus 6.0 IU/mg protein. Six additional dogs received insulin following the 15 minute epicardial map and blood sugar was maintained at a level of 46 plus or minus 6 mg per cent for the 24 hours. These dogs showed more myocardial necrosis than predicted by the ST-segment elevation prior to insulin administration. Forty-six percent of sites, which in control dogs would have been expected to have normal CPK and histological appearance, showed depressed CPK activity and histological evidence of early myocardial necrosis. Thus, hypoglycemia increases myocardial damage, as reflected by enzymatic and histological analyses.
Persistence of MB isoenzyme of creatine phosphokinase in the serum after minor iatrogenic cardiac trauma. Absence of postmortem evidence of myocardial infarction.
Authors: Tonkin A M , Lester R M , Guthrow C E , Roe C R , Hackel D B , Wagner G S
Published: June 2012

The specificity of serum CPK-MB for acute myocardial infarction was examined by retrospective analysis of 401 consecutive patients admitted to Coronary Care Unit over a three and one-half year period with suspected infarction in whom the isoenzyme was subsequently detected. Four patients (1 per cent) who died during the hospital admission had no autopsy evidence of acute myocardial infarction. All four had experienced mild iatrogenic cardiac trauma, following which serum CPK-MG persisted for at least 24 hours. In one patient, a permanent pacemaker had been inserted by the transmediastinal approach. Two patients had been subjected to closed chest cardiac massage and intracardiac puncture, and one to external cardiac massage alone. The findings suggest that persistent identification of serum CPK-MB, although specific for myocardial necrosis, cannot be regarded as diagnostic of myocardial infarction. The implications of this are important to treatment of patients after cardiopulmonary resuscitation and operative trauma to the heart.
Effects of nitroglycerin and nitroglycerin-methoxamine during acute myocardial ischemia in dogs with pre-existing multivessel coronary occlusive disease.
Authors: Myers R W , Scherer J L , Goldstein R A , Goldstein R E , Kent K M , Epstein S E
Published: June 2012

Nitroglycerin (TNG) reduces ischemic injury during acute coronary occlusion in dogs with otherwise normal coronary arteries, but its effect in the presence of pre-existing multivessel coronary disease is unknown. We therefore examined the influence of TNG on acute ischemia in dogs with chronic multivessel coronary occlusions. The left anterior descending (LAD) coronary artery was acutely occluded by a balloon cuff in conscious dogs two weeks after placement of ameroid constrictors to produce gradual occlusion of the obtuse marginal and posterior descending coronary arteries. Adequacy of balloon and ameroid coronary occlusion and degree of collateralization were assessed by coronary angiography. Nitroglycerin decreased arterial pressure and increased heart rate. Myocardial ischemia, determined after LAD occlusion by summing ST-segment elevation (sigmaST) from eight intramyocardial electrodes, lessened with TNG in those six dogs whose heart rate increased less than 50 per cent, but increased in those four whose heart rate increased greater than 50 per cent. When TNG-induced change in either heart rate or arterial pressure was prevented by adding methoxamine, sigma ST was diminished even more (avg decrease 25 per cent; P smaller than 0.05). We conclude that, in the presence of pre-existing multivessel coronary occlusions, 1) TNG reduces ischemic injury during experimental acute coronary occlusion provided arterial pressure and heart rate responses are not excessive and 2) uniform improvement occurs when pressure and rate responses are abolished by an alpha-adrenergic agonist. Although results in animal studies must be extrapolated to the clinical situation with caution, these findings suggest that a similar pharmacologic approach might be applicable to the treatment of acute myocardial infarction in man, even in the presence of multivessel disease.
Modification of ventricular fibrillation latency following coronary artery occlusion in the conscious pig.
Authors: Skinner J E , Lie J T , Entman M L
Published: June 2012

Abrupt occlusion of the left anterior descending coronary artery was performed on 45 unanesthetized farm pigs in order to evaluate the relative effects on the latency to ventricular fibrillation (VFL) of 1) adaptation of the animals to the laboratory, and 2) beta-receptor blockade by propranolol. Compared to control values, VFL was greatly lengthened (i.e., VF delayed or prevented) by adaptation (P smaller than 0.01), was shortened by large (2 MG/KG) doses of racemic propranolol in unadapted animals (P smaller than 0.02), and was again increased while under the influence of the drug, by adaptation (P smaller than 0.051). Neither a lower (0.02 mg/kg) dose of racemic propranolol, 2 mg/kg of dextropropranolol, nor ventricular pacing to a higher heart rate had an effect on VFL. The results suggest that reduced psychological stress was very effective in retarding or preventing the onset of VF, that low doses of propranolol were ineffective, and that higher doses were deleterious in unadapted animals.
The evaluation of left ventricular function in man. A comparison of methods.
Authors: Kreulen T H , Bove A A , McDonough M T , Sands M J , Spann J F
Published: June 2012

Comparisons of the sensitivities of parameters for assessing left ventricular performance in man were made in 38 patients. The parameters compared were the ejection fraction, ventriculographic contraction patterns, the left ventricular end-diastolic pressure, and the contractile indices including the contractile element velocity at 10 mm Hg (Vce 10) and maximal contractile element velocity (Vmax). The contractile indices were obtained by catheter tip manometry, utilizing developed pressure (DP) to calculate the velocity of contractile element shortening (Vce) from the formula: dp/dt divided by 32 DP. Vce 10 was measured directly and Vmax was derived by linear manual extrapolation of the pressure-velocity plot to 0 mm Hg. Vmax values derived from linear manual extrapolation were compared with values obtained by computer least squares fitting of the Vce and developed pressure data points to single and double exponential equations. The Vce and developed pressure data points fit the single exponential equation better than the double exponential equation but the use of either equation resulted in slightly higher values for Vmax than obtained with linear manual extrapolation. The effect of heart rate on myocardial contractility was eliminated by making comparisons at both a basal and atrial paced rate of 100. Utilizing all methods, 24 patients were identified to have ventricular dysfunction. The contractile indices were significantly less sensitive than any other parameter (P smaller than 0.05) and identified seven patients while the left ventricular end-diastolic pressure, ejection fraction, and presence of asynergy identified 15, 15, and 12 patients, respectively. The use of a common atrial paced rate of 100 did not increase the sensitivity of the contractile indices. Since there was only partial overlapping between parameters in the identification of left ventricular dysfunction, the combination of different parameters was more sensitive than any single parameter alone. It is concluded that several methods are required to identify all patients with left ventricular dysfunction and that the contractile indices are the least sensitive indicator of left ventricular dysfunction.
Echocardiographic determination of left ventricular stress-velocity relations.
Authors: Quinones M A , Gaasch W H , Cole J S , Alexander J K
Published: June 2012

The time course of left ventricular (LV) circumferential stress and fiber shortening velocity (Vcf) were determined at 20 msec intervals in 30 patients from simultaneous recordings of LV pressure (micromanometer) and LV dimensions (echography). In 12 patients with normal LV function, endocardial and midwall maximal (max) Vcf, Vcf at peak stress, and endocardial mean Vcf were significantly greater than in eight patients with myocardial disease. Peak stress was less in the normal subjects (mean equal 241 gl/cm2, range 180 to 310 g/cm2) than in those with myocardial diseases (mean equals 371 g/cm2, range 280 to 513 g/cm2). Vcf was reduced in five out of seven patients with chronic LV volume overload, while peak stress ranged from normal in three to increased in four. Max Vcf, mean Vcf, and peak stress were normal in three patients with chronic LV pressure overload; Vcf at peak stress was normal in two. Good correlation was observed between angiographic determinations of mean Vcf and endocardial max Vcf, Vcf at peak stress and mean Vcf. Induced changes in preload in five patients (dextran infusion at constant heart rate) produced a 12.2 per cent increase in peak stress (P small than 0.05), and insignificant changes in max Vcf (3.7 per cent increase, P = NS), in Vcf at peak stress (5 per cent decrease, P smaller than 0.05), in mean Vcf (0.7 per cent increase, P = NS). Increasing afterload with angiotensin in seven patients (peak stress increased by 45 per cent, P smaller than 0.01) reduced max Vcf, Vcf at peak stress and mean Vcf by 33 per cent, 39 per cent respectively. Lowering afterload in one patient (amyl nitrite) produced an increase in Vcf. Improvement in Vcf was observed in all instances during positive inotropic stimulation (isoproterenol in three normals, digoxin in four with myocardial disease). Thre response of endocardial and midwall Vcf to loading and contractility were similar. In man Vcf is an index of myocardial contractility which is affected minimally by changes in preload but responds inversely to changes in afterload. Its sensitivity to acute afterload changes may, at times, limit its clinical applicability.
Serum digitoxin concentrations in infants and children.
Authors: Giardina A C , Ehlers K H , Morrison J B , Engle M A
Published: June 2012

Serum digitoxin levels were measured in 18 infants (under two years) and in 23 children (aged 2-13 years) receiving maintenance therapy. Digitalization was carried out because of heart failure in 17 infants and 13 children and for control of dysrhythmia in one infant and 10 children. Mean maintenance dosage for infants was 0.0042 plus or minus 0.0008 (sd) mg/kg/day and for children was 0.0031 plus or minus 0.0012 mg/kg/day. The mean serum digitoxin level was not significantly different in infants (30 plus or minus 10 ng/ml, range 14-58) from that found for children (34 plus or minus 11 ng/ml, range 19-61). Both values were significantly different (P smaller than 0.001) from those determined in this laboratory for adults (mean 24 plus or minus 7 ng/ml, range 5-39). In four infants with electrocardiographic or other evidence of toxicity, the mean serum level was 71 plus or minus 2 ng/ml (range 68-72), and in four children with electrocardiographic or other evidence of toxicity, the mean serum level for digitoxin was 72 plus or minus 14 ng/ml (range 53-84). The data suggest that infants and children tolerate a higher serum digitoxin concentration without any evidence of toxicity and may require more digitoxin (mg/kg) for therapeutic effect than do adults. Serum digitoxin levels may serve as an important guide in determining the adequacy of digitalization and in the recognition and management of digitalis toxicity.
Congenital mitral valve disease in transposition of the great arteries.
Authors: Rosenquist G C , Stark J , Taylor J F
Published: June 2012

A spectrum of mitral valve disease was noted in 71 per cent of 163 specimens with transposition of the great arteries. At one end of the spectrum were hearts with normal mitral valve, except that the free margin of the anterior leaflet was shortened; at the other end were specimens with underdevelopment of the space between or behind the papillary muscles of the left ventricle. In additional specimens the anterior leaflet was indented and attached by chordae tendineae to the ventricular septum.
Reduced baroreceptor sensitivity in borderline hypertension.
Authors: Takeshita A , Tanaka S , Kuroiwa A , Nakamura M
Published: June 2012

The sensitivity of the baroreceptor reflex in nine patients with borderline hypertension (mean age 19.1 plus or minus 0.2 years) was compared to that in six normal subjects of comparable age (mean 18.8 plus or minus 0.3 years) and that in 14 patients with established hypertension (mean age 48.3 plus or minus 3.1 years). The sensitivity of the baroreceptor reflex was assessed by determining the slope of the regression line relating the rise of systolic pressure to the prolongation of the R-R Interval during the transient rise of arterial pressure induced by an intravenous injection of phenylephrine. The average baroreceptor slope in nine patients with borderline hypertension was 9.1 plus or minus 0.8 msec/mm Hg, which was significantly less than that in six normal subjects (16.0 plus or minus 2.0; P smaller than 0.01), but was greater than that in 14 patients with established hypertension (4.9 plus or minus 0.7; P smaller than 0.01). The significant negative correlation was found as the baroreceptor slope was related to the mean arterial pressure in patients with borderline hypertension and normal subjects, all of whom were 20 years old or less. Attenuation of the baroreceptor sensitivity may influence the maintenance of raised arterial pressure in borderline hypertension.
De subitaneis mortibus. XI. Young girl with palpitations.
Authors: James T N , Marilley R J , Marriott H J
Published: June 2012

A seventeen-year-old girl in apparent good health was found dead in bed one morning. Two clinical features of note were multiple premature beats present in her electrocardiograms for several years, and a tall thin habitus without stigmata of Marfan's syndrome. At necropsy examination the heart was grossly normal. At its margin abutting the central fibrous body the atrioventricular (A-V) node exhibited numerous fronds and outcroppings, some forming loop connections from one part of A-V node to another. Groups of A-V nodal cells detached from the A-V node were also found connected to the crest of the interventricular septum. There were large connections directly from the His bundle to the crest of the interventricular septum (Mahaim fibers). The A-V node artery was moderately narrowed but patent. The possible significance of these findings in the pathogenesis of re-entrant arrhythmias or ectopic automaticity is discussed.
Catheter positions in congenital cardiac malformations.
Authors: Taketa R M , Sahn D J , Simon A L , Pappelbaum S J , Friedman W F
Published: June 2012

Biplane cineangiocardiograms were examined from a population of patients with diverse forms of congenital heart disease and examples were selected to illustrate catheter positions which may help define and elucidate the anatomy of simple and complex cardiac lesions. Familiarity with the appearance of these typical and atypical catheter positions may be of considerable aid in the course of hemodynamic study and in the evaluation of cineangiocardiograms. The editors suggest that each figure be evaluated as an unknown before reading the caption.
Wolff-Parkinson-White syndrome. The problem, evaluation, and surgical correction.
Authors: Gallagher J J , Gilbert M , Svenson R H , Sealy W C , Kasell J , Wallace A G
Published: June 2012

Physiological studies of the type we have described, when performed in patients with the WPW syndrome, can yield diagnostic information regarding the mechanism of arrhythmia, demonstrate functional properties of therapeutic import, facilitate therapeutic decision-making about drug regimens and presumptively localize the site of pre-excitation as a basis for possible surgical intervention. Based on our experience, we feel that in selected patients, surgical correction of the WPW syndrome is entirely feasible, and can be accomplished in the majority of patients in whom free wall A-V connections are present. The continuing challenge of identification and correction of septal accessory pathways directs our present work with the WPW syndrome.
Extracardiac recordings of His-Purkinje activity during conduction disorders and junctional rhythms.
Authors: Berbari E J , Lazzara R , El-Sherif N , Scherlag B J
Published: June 2012

Previous investigations have demonstrated a surface recording technique using signal averaging to detect electrical activity during the "isoelectric" P-R segment. Various physiological and pharmacological interventions suggest that the source of these potentials isthe His-Purkinje system (HPS). In order to assess the sensitivity of averaged recordings to changes in HPS activation, i.e., conduction defects in the HPS recordings were made directly from the heart surface using a bipolar, anterior-posterior epicardial lead in 15 dogs which underwent thoractomy. The signal was amplified, filtered and averaged using a digital computer for purposes of signal enhancement. The epicardial averaged lead (EAL) contained activity coincident with HPS depolarization and similar to those recorded by leads on the body surface of intact dogs from previous studies. The standard ECG and His bundle electrogram from an electrode catheter served as references in localizing and assessing several conduction disorders experimentally produced by traumatic and ischemic injury. Among the disorders produced were: 1) atrioventricular (A-V) nodal block which resulted in loss of recorded activity in the EAL following the P wave. 2) First and second degree intra-His bundle block produced by anterior septal artery ligation showed split His potentials in the HBE (1 degree) and 2:1 conduction with block in the His bundle (2 degrees). In the blocked beats the EAL showed a reproducible portion of the activity coincident with proximal His bundle activity of the split His potentials in both cases. 3) In four cases of proximal right bundle branch block produced by anterior septal artery ligation the relatively proximal portions of HPS activity in the EAL showed marked diminution. 4) Two cases of distal His bundle or bilateral bundle branch delay were seen as prolonged H-V time and a normal QRS pattern. The early and late portions of the HPS activity in the EAL were not markedly changed while the middle portion was prolonged and fractionated. 5) Junctional rhythms produced by crushing the SA node resulted in no atrial activity occurring prior to HPS depolarization in the EAL. However, the QRS was preceded by HPS activity whose onset was coincident with the H recorded in the His bundle electrogram. The EAL showed consistent and reproducible morphology and timing of HPS activity at different heart rates during normal conduction and consistent alterations of the HPS activity during abnormal conduction.
Early onset of pulmonary vascular obstruction in patients with aortopulmonary transposition and intact ventricular septum.
Authors: Lakier J B , Stanger P , Heymann M A , HoffmaN J I , Rudolph A M
Published: June 2012

Of 29 patients with aortopulmonary transposition with intact ventricular septum who underwent cardiac catheterization as neonates, five subsequently developed increased pulmonary vascular resistance at an early age (7 months to 2 1 2 years). The resistance was high in two patients (11.0 and 12.9 units (U)/m-2), moderate in one (5.5 U/m-2) and mild in two (3.6 and 4.6 U/m-2). The two patients with the highest resistances died as a result of the pulmonary vascular obstruction and it was probably a contributing factor in the death of a third patient. The finding of pulmonary vascular obstruction at an early age in five of 29 patients with transposition of the great arteries with intact septa is noteworthy. It assumes even greater significance as the measurement methods tend to underestimate pulmonary vascular resistance. The possible errors in assessing pulmnary vascular resistance and factors possibly contributing to early development of pulmonary vascular obstruction are discussed.
Radioisotopic bolus technique as a test to detect circulatory deficit associated with cerebral death. 142 studies on 80 patients demonstrating the bedside use of an innocuous IV procedure as an adjunct in the diagnosis of cerebral death.
Authors: Korein J , Braunstein P , Kricheff I , Lieberman A , Chase N
Published: June 2012

A portable radioisotopic technique was developed to demonstrate cerebral circulatory deficit, as part of a collaborative study to define and diagnose cerebral death simply and rapidly, in comatose, apneic patients with electrocerebral silence. The method involves an intravenous injection of 2mCi of 99mTcO4, and recording time/activity curves over the cranial cavity and a femoral artery simultaneously, using twin probe radioisotope detector equipment. Eight comatose, apneic patients had 142 studies in conjunction with clinical electroencephalographic and other laboratory evaluations. The results indicate that the absence of a bolus tracing from the head, as contrasted to the usual bolus seen is indicative of significant circulatory deficit to the cerebrum. This test may be used as an adjunct in confirming the diagnosis of cerebral death. A normal bolus tracing should be simultaneously observed over a femoral artery and this is used as a control. The method is safe and simple and offers significant information about the irreversibility of cerebral blood flow. Although further studies are indicated, the method appears to be most promising as a fundamental bedside laboratory test in the diagnosis of cerebral death in conjunction with other clinical and laboratory criteria.