bluuebunny/crossref_metadata_2025 huggingface dataset:
Alterations in preload and ejection phase indices of left ventricular performance,.
Authors: Rankin L S , Moos S , Grossman W
Published: June 2012

Ejection phase indices such as mean velocity of circumferential fiber shortening (V-cf), ejection fraction (EF), and mean normalized systolic ejection rate (MSER) are thought to reflect the level of left ventricular (LV) inotropic state. Although known to be influenced by changes in afterload, their response to altered preload is less certain. This question was examined in ten normal subjects studied in the supine position and after 10 min of 75 degree head-up tilt. Echo VL diameter (D) and carotid pulse recordings were used to calculate LV ejection time, V-cf, MSER, LV end-diastolic and stroke volumes (EDV and SV, by D3 formula), and ejection fraction. Systemic blood pressure (BP)was measured by cuff, and heart rate (HR) counted from the ECG. Calculated LVEDV decreased with tilt (115 plus or minus 8 to 82 plus or minus 7 ml, P smaller than 0.001), as did SV (81 plus or minus 6 to 54 plus or minus 6 ml, P smaller than 0.001), and ejection time (0.31 plus or minus 0.01 to 0.27 plus or minus 0.00 sec, P smaller than 0.001), but there was no significant change in systolic or diastolic BP or HR. V-cf, EF, and MSER were not singificantly altered by tilt (1.09 plus or minsu 0.04 to 1.12 plus or minus 0.05 circ/sec; 0.70 plus or minus 0.02 to 0.65 plus or minus 0.02; and 2.29 plus or minus 0.07 to 2.43 plus or minus 0.08 end-diastolic volumes/sec, respectively). V-cf, MSER, and EF appearrelatively unaffected by acute alterations in preload. That compensatory sympathetic responses blunted potential changes cannot be excluded, although HR was not found to have increased.
Electroide cather recording during malignant ventricular arrythmia following experimental acute myocardial ischemia. Evidence for re-entry due to conduction delay and block in ischemic myocardium.
Authors: El Sherif N , Scherlag B J , Lazzara R
Published: June 2012

In 20 anesthetized opened-chest dogs, plunge wire and electrode catheter recordings of the this bundle electrogram which also showed septal activation, were monitored before and after ligation of the anterior septal artery. The average time to onset of ventricular tachycardia after ligation was 5-1/2 min. The evolution of the arrhythmia was temporally related to progressive fragmentation and delay of the septal potential, resulting in a marked increase in total ventricular activation time (up to 335 msec). In six experiments the fragmented, delayed septal depolarization was inscribed well beyond the T wave of the surface QRS prior to the onset of arrhythmias. Various conduction disorders involving the ischemic septal myocardium were observed which closely correlated to the patterns of conduction disorder in the ischemic proximal His-Purkinje system. First degree block, 2 degree block of the Mobitz II and Wenckebach types, higher degree block and paroxysmal complete block occurred. The onset of the arrhythmia was characteristically associated with a Wenckebach pattern of conduction delay of a part of the septal deflection. Conduction disorders of the ischemic myocardium were tachycardia-dependent. Bradycardia resulted in recovery of form, duration, and timing of the septal potential with the coincident disappearance of ventricular arrhythmias. The study shows that the basic prerequisites for re-entry do exist during the early period following occlusion of a major coronary artery and can explain the malignant phase of ventricular arrhythmias. Similar disorders in man may be detected by intracardiac electrode catheter recordings.
Transient ST-segment in unstable angina. Clinical and hemodynamic significance.
Authors: Plotnick G D , Conti C R
Published: June 2012

The significance of the direction of the ST-segment shifts on the 12-lead electrocardiogram was evaluated in 82 consecutive patients with unstable angina. Eighteen patients with ST-segment elevation (group I) were compared with 64 patients with ST-segment depression (group II). There was no difference between group I and group II with regard to age, sex, or history of previous myocardial infarction. There also was no difference in the angiographic extent, location or severity of the coronary artery disease, collaterals, or resting hemodynamics. A larger proportion of patients in group I presented with recent onset angina. Life-threatening arrhythmias were more frequent in group I but were uncommon in both groups. A normal resting electrocardiogram was associated with normal ventricular function in both group I and group II but was associated with single vessel disease only in group I. An abnormal resting electrocardiogram was associated with multiple coronary vessel disease and abnormal ventricular function in both groups. Single vessel disease was encountered twice as frequently in group I but this difference was not statistically significant. Left main coronary artery disease was found only in group II.
Postoperative left anterior hemiblock and right bundle branch block following repair of tetralogy of Fallot. Clinical and etiologic considerations.
Authors: Steeg C N , Krongrad E , Davachi F , Bowman F O , Malm J R , Gersony W M
Published: June 2012

Previous reports have indicated an incidence of right bundle branch block (RBBB) and left anterior hemiblock (LAH) pattern varying from 8-22% following corrective surgery in patients with tetralogy of Fallot. Among 207 patients with tetralogy of Fallot operated on at our institution, 8.7% developed an ECG pattern of RBBB and LAH. These patients were followed for 1-13 years (mean 6.2 years) for a total of 111 patient years. All patients are alive and none have had documented late atrioventricular dissociation, syncope, or other symptoms. Transient heart block was present in one patient in the immediate postoperative period but has not recurred. This group of patients differs significantly from other series in which such an ECG pattern was associated with a marked increase in morbidity and mortality. These data and the experimental evidence suggest that two distinct groups of patients exist: 1) a group in which this ECG pattern is secondary to lesions within the bundle of His and 2) a group in which the pattern is caused by lesions in the peripheral conduction system. It is postulated that these two groups which demonstrate the same ECG pattern may carry significantly different prognoses. Analysis of H-V intervals postoperatively may help identify patients at risk.
The effect of cold air inhalation on again pectoris and myocardial oxygen supply.
Authors: Hattenhaur M , Neill W A
Published: June 2012

Inhalation of cold air (-20 degrees C) for four minutes provoked angina pectoris in four of 17 coronary disease patients at rest and in four of seven of the patients while they were paced at a heart rate level which was subanginal at room temperature. The cold air did not increase myocardial O2 consumption significantly, and the accompanying changes in systemic hemodynamic factors known to influence myocardial O2 consumption were minor. Coronary blood flow determined by the xenon clearance method did not change significantly. In 18 patients, cold air inhalation for 1 1/2 minutes caused no detectable constriction of coronary arteries visualized arteriographically. We conclude that angina pectoris induced by breathing cold air cannot be explained satisfactorily by a concurrent increase in myocardial work and O2 consumption. Although neither large coronary artery constriction nor generalized coronary arteriole constriction seem to be involved, some other specific effect of cold air inhalation on coronary vasomotion, perhaps affecting collaterals or coronary blood flow distribution, is suspected.
Pathology of stable and unstable angina pectoris.
Authors: Guthrie R B , Vlodaver Z , Nicoloff D M , Edwards J E
Published: June 2012

The clinical and pathological data from 46 patients who died during or shortly after coronary bypass surgery and one patient who died shortly after angiography were studied. Each patient was placed into one of three clinical categories of angina pectoris. Twelve were classified as having unstable angina pectoris, 20 as stable severe angina, and 15 as stable moderate angina. No significant difference was found between the three catagories whem age, sex, presence of hypertension, lipid abnormalities, diabetes, smoking, family history of myocardial infarction, or history of previous mycardial infarction were examined. Most patients in all classes of angina had extensive atherosclerotic coronary disease: 12 patients had triple vessel plus left main disease; 25, triple vessel disease; nine double vessel disease; and only one, single vessel disease. There was no difference in severity or distribution of coronary disease when the three catagories of angina were compared. Thirty-six of the 47 patients had evidence of scarring of one or more aspects of the left ventricular wall. There was likewise no significant difference between extent and distribution of myocardial scarring between the three clinical categories. Four of the 12 patients with unstable angina pectoris had pathologic evidence of preoperative myocardial infarction, whereas this was not found in any of the 35 patients with stable angina.
Ventricular function before and after direct revascularization surgery. A proposal for an index of vascularization to correlate angiographic and ventriculographic findings.
Authors: Levine J A , Bechtel D J , Cohn P F , Herman M V , Gorlin R , Cohn L H , Collins J J
Published: June 2012

In order to determine the effect of direct bypass surgery on the total coronary arterial supply to the heart, a numerical construct was devised to incorporate the development of new obstructive lesions and the presence of patent or nonpatent grafts. This construct, termed a vascularization index (VI), was used to evaluate left ventricular function and anginal symptoms after coronary artery bypass surgery in 56 patients. Patients with an increase in local or total arterial blood supply (positive delts VI) often had similar directional changes in segmental wall motion and ventricular ejection fraction. Patients with a decrease in local or total arterial blood supply (negative delta VI), due to either nonpatent grafts or progression of atherosclerotic disease, also usually had similar directional changes in segmental wall motion and ventricular ejection fraction. (Although nearly all patients reported a decrease in anginal symptoms after surgery, delta VI could not identify degree of improvement.) Use of an integrated approach in describing pre and postoperative myocardial blood supply appears to be the most reliable method of explaining changes in left ventricular function.
Observations on blood viscosity changes after acute myocardial infarction.
Authors: Jan K M , Chien S , Bigger J T
Published: June 2012

Serial blood rheologic measurements were made in 25 patients with acute myocardial infarction; measurements included blood and plasma viscosities, hematological data and plasma protein concentrations. The blood viscosity was elevated on admission and for more than 21 days after acute myocardial infarction. However, the cause of the elevated viscosity was changed as a function of time after acute myocardial infarction. During the first three days after admission, the high blood viscosity was mainly attributable to high hematocrit values. Thereafter, the hematocrit fell, but blood viscosity remained high. High blood viscosity after the first three days of acute myocardial infarction can be correlated with increases in plasma viscosity and red cell aggregation, which in turn are explained by elevations of alpha 2 globulin and fibrinogen concentrations. Patients with higher blood viscosity on admission had a significantly higher incidence of complications, i.e., shock, thromboembolism and left ventricular failure.
Great vessel, cardiac chamber, and wall growth patterns in normal children.
Authors: Epstein M L , Goldberg S J , Allen H D , Konecke L , Wood J
Published: June 2012

The purpose of this study was to establish normal echocardiographic measurements of valvular motion, cavity dimensions, great vessel diameters, and right, left and septal wall thicknesses of children ranging in size from infants to full growth. The study group was composed of 205 normal, healthy children for whom echocardiograms and subsequent measurements were performed in a standardized manner. The following measurements were performed: left ventricular end-diastolic and end-systolic dimension, right ventricular end-diastolic cavity dimension, right ventricular end-diastolic anterior wall thickness, left ventricular end-diastolic posterior wall thickness, ventricular septal end-diastolic thickness, maximal left atrail dimension, end-diastolic aortic and pulmonary artery diameter, end-diastolic cardiac and septal depth, maximal aortic leaflet separation, and maximal anterior mitral and anterior tricupsid amplitude. Data are grouped into the fifth, fiftieth, and ninety-fifty percentiles according to body surface area. These graphs allow measurements of a single patient to be compared to normal measurements of individuals with similar body surface area.
The basis for differences in ethanol-induced myocardial depression in normal subjects.
Authors: Timmis G C , Ramos R C , Gordon S , Gangadharan V
Published: June 2012

The acute effects of ethanol (ETOH) on cardiac function in 32 normal subjects has been studied utilizing systolic time intervals. Seven (group I) 13 (group II), and 12 subjects (group III), reported an average daily consumption of less than 1 oz, 1-2 oz, and more than 2 oz of ETOH, respectively. Progressively higher control values from group I to group III in PEP, PEPI, ICT and PET/LVET were observed (PEP-I vs PEPI-III: P smaller than 0.05; PEP/LVET-I vs PEP/LVET-II and PEP/LVET-III: P smaller than 0.05). There was progressively less change in these variables following acute ETOH (P smaller than 0.02-0.05 in group I; P equals NS in group III, group II intermediate). This indicates some degree of chronic myocardial impairment in group II and especially in group III, which tends to be proportionate to the degree of chronic ETOH exposure. These data are not necessarily disparate with previous reports of little or even a salutary hemodynamic effect of ETOH in normal subjects. Thus, the relative stability of LVET post ETOH, coupled with the observed increase in heart rate, is consistent with previous reports of ETOH-induced rate-dependent increments in cardiac output with unchanging stroke volumes, in spite of the presence of acute myocardial depression. The observations reported herein demonstrate the probable incremental influence of ETOH consumption in a chain of events which may culminate in alcoholic cardiomyopathy.
The effects of right atrial and ventricular pacing on the auscultatory findings in patients with mitral valve prolapse.
Authors: Towne W D , Rahimtoola S H , Sinno M Z , Loeb H S , Rosen K M , Gunnar R M
Published: June 2012

Fifteen patients with midsystolic clicks associated with mitral valve prolapse were studied in order to assess changed in ausculatatory findings produced by pacing-induced variations in cardiac rate, rhythm, and conduction. As the heart rate was increased in stepwise intervals to the maximum possible extent by right atrial pacing (RAP) in 14 patients, the interval between the Q wave and the click (Q-C) decreased in all cases (21 plus or minus msec/10 beats/min; P smaller than 0.001). In two patients, RAP at rates of and above 118 and 159 per minute, respectively, resulted in disappearance of the click. During right ventricular pacing (RVP) without evidence of atrioventricular (A-V) dissociation on the surface ECG in ten patients, the click was inaudible at all pacing rates in three instances. In all seven of the cases in which the click was audible at the lowest rate of RVP with VA conduction, Q-C was greater and C-S2 less than that in sinus rhythm. As the rate of RVP was increased, Q-C was noted to decrease (26 plus or minus 4 msec/10 beats/min) and C-S2 to increase (19 plus or minus 7 msec/10 beats/min) in all patients. In three patients in whom RVP induced atrioventricular dissociation, the click was seen only in beats closely preceded by a P wave. In ten of 11 patients the click occurred earlier in systole with a postextrasystolic or post tachycardia beat as compared to its appearance after a sinus beat when a shorter preceding diastolic filling period was present (P smaller than 0.001). In the eleventh patient a loud systolic murmur was present during a postextrasystolic cycles. It is concluded that pacing-induced rhythm disturbances can result in disappearance of a midsystolic click or can alter its timing and cause it to mimic sonic phenomena seen in other disease states. The possibility of similar changes taking place as a result of spontaneously occurring disturbances of rate, rhythm, and conduction should be recognized in order that the possible diagnosis of mitral valve prolapse not be overlooked.
Unusual examples of supraventricular re-entrant tachycardias.
Authors: Wellens H J
Published: June 2012

Programmed electrical stimulation of the heart uncovered unusual findings in four patients suffering from supraventricular tachycardias. They included 1) two supraventricular tachycardias of different location and frequency in the same patient, 2) increase in rate of a re-entrant atrioventricular (A-V) nodal tachycardia followed by the development of 2-to-1 A-V block, 3) a "gap" in A-V conduction and A-V nodal re-entrant tachycardia with 2-to-1 A-V block, and 4) the initiation of atrial re-entrant tachycardia by ventricular premature beats. The examples are given to help elucidate the understanding of mechanisms involved in re-entrant tachycardias and to localize the site of the re-entry circuit.
Digoxin induced intestinal vasoconstriction. The effects of proximal arterial stenosis and glucagon administration.
Authors: Levinsky R A , Lewis R M , Bynum T E , HANLEY H G
Published: June 2012

Previous studies have been shown that intravenous cardiac glycosides produce mesenteric vasoconstriction (MVC). The possibility that this might critically compromise blood flow in patients with mesenteric vascular disease was suggested. To evaluate whether MVC occurs with intravenous cardiac glycosides in the presence of proximal mesenteric artery stenosis, blood flow in the superior mesenteric artery (SMA) of thirteen dogs was measured with a Doppler flowmeter. The SMA was constricted and pressures were measured in the aorta, SMA, and superior mesenteric vein. Superior mesenteric vascular resistance (SMVR) was calculated by dividing the pressure difference between the SMA and superior mesenteric vein by the total blood flow to the superior mesenteric vasculature and was reported as mm Hg/cc-min. Blood flow was measured simultaneously by a drop rate meter in the vein of a surgically isolated intestinal segment supplied by a single arterial arcade. Venous outflow pressure from this segment was also monitored, which allowed calculation of isolated gut segment resistance (IGSR) in mm Hg/cc-min per 100 g gut. Stenosis of the SMA produced pressure gradients of 10 to 75 mm Hg and decreased resting blood flow by as much as 82%. Digoxin produced an increase in both SMVR and IGSR throughout the 30 to 120 minute period of the study in thirteen dogs despite the presence of severe grades of SMA stenosis. There was no relationship between the degree of proximal SMA stenosis and the magnitude of resistance change due to digoxin. To determine if this MVC was reversible, glucagon was administered to eleven dogs 30 to 60 minutes after digoxin and completely overcame the constriction. Thus, digoxin produced MVC in the presence of proximal SMA stenosis. This MVC was pharmacologically reversible. These data suggest that intravenous digoxin might contribute to intestinal ischemia in patients with preexisting vascular disease.
Venous flow velocity, venous volume and arterial blood flow.
Authors: Coffman J D , Lempert J A
Published: June 2012

The relationship of arterial blood flow and venous volume to venous flow velocity was studied in normal subjects. The effects of current modes of treatment in venous thrombosis and of a vasodilator drug on venous flow velocity were also investigated. Total calf flow and venous volume were measured by venous occlusion plethysmography while venous flow axial velocity was determined by the transit time of 131-I albumin from calf to inguinal region. Local intravenous epinephrine administration induced venoconstriction and increased venous flow velocity. Intra-arterial isoproterenol and angiotensin increased and decreased arterial flow, respectively, with no change in venous flow velocity of volume, but local heat increased arterial flow and venous flow velocity with no change in venous volume. Local cold, despite venoconstriction, decreased venous flow velocity accompanied by a decreased arterial flow. Intravenous heparin did not affect venous flow velocity. Intravenous but not oral nylidrin increased venous flow velocity. Therefore venous flow velocity can be significantly increased by venocontriction, by large increases in arterial flow (local heat), and by a parenteral vasodilator drug. These experiements indicate that there is a basis for applying heat but not cold in the prevention and treatment of venous thrombosis.
Blood pressure, sodium intake, and sodium related hormones in the Yanomamo Indians, a "no-salt" culture.
Authors: Oliver W J , Cohen E L , Neel J V
Published: June 2012

The Yanomamo Indians are an unacculturated tribe inhabiting the tropical equatorial rain forest of northern Brazil and southern Venezuela who do not use salt in their diet. The group therefore presented an unusual opportunity to study the hormonal regulation of sodium metabolism in a culture with life-long extreme restriction of dietary sodium, with parallel observations on blood pressure. Blood pressures increased from the first to second decade but, in constrast to civilized populations, do not systematically increase during subsequent years of life. In twenty-four hour urine collections on adult male Indians, excretion of sodium averaged only 1 plus or minus 1.5 (SD) mEq. Simultaneous plasma renin activities were elevated and comparable to those of civilized subjects placed for brief periods on 10 mEq sodium diets. Similarly, excretion rates of aldosterone equaled those of acculturated subjects on low sodium diets. The findings suggest that the hormonal adjustments to life-long low sodium intakes are similar to those achieved in acute sodium restriction of civilized man. Parenthetically, these elevated levels of aldosterone and renin were probably the norm for man during much of human evolution and suggest that the values observed in civilized controls are depressed by an excessive salt intake in contemporary diets.
Digitalis and the sick sinus syndrome. Clinical and electrophysiologic documentation of severe toxic effect on sinus node function.
Authors: Margolis J R , Strauss H C , Miller H C , Gilbert M , Wallace A G
Published: June 2012

Digoxin, in a common clinical dose and at a low serum level, brought out severe manifestations of sinus node dysfunction in a patient who had previously undergone successful mitral valve replacement. This report presents the results of extensive clinical and electrophysiologic studies of this patient before and after a digoxin challenge. In the absence of cardiac glycoside, the only demonstrable abnormalities of sinus node function were mild resting sinus bradycardia and failure to respond to atropine administration. Responses to isoproterenol administration, programmed premature atrial stimulation, and overdrive pacing at several cycle lengths were normal. Following the administration of intravenous digoxin, 1.025 mg/24 hrs, the resting sinus cycle length increased and the response to overdrive pacing became markedly abnormal. The latter was followed by sinus pauses in excess of six seconds, even at relatively slow overdrive pacing rates. The electrophysiologic and clinical implications of these data are discussed. It is suggested that despite previous reports that digitalis preparations are relatively well tolerated by patients with sick sinus syndrome, caution should be used when administering these drugs to this group of patients.
Myocardial revascularization combined with intracoronary infusion of hyperosmolar solution in the early management of postinfarction ventricular septal defect. Report of a case.
Authors: Jones E L , Tyras D H , King S P , Logue R B , Hatcher C R
Published: June 2012

A patients is described with postinfarction ventricular septal defect in whom the perforation was successfully closed within 24 hours of septal rupture. This presents the second such case reported in the literature. Adjunctive measures consisting of myocardial revascularization and intracoronary infusion of mannitol were thought to be important in the successful outcome of the operative procedure. The importance of complete preoperative cardiac catheterization with coronary arteriography is stressed. The theoretical role of endothelial and myocardial cellular edema as a cause of depressed myocardial function immediately following an ischemic insult is proposed as a practical consideration in the high mortality associated with this condition. Methods used to prevent or reverse such cell swelling are described. The details of the operation in which viable ventricle myocardium was used to fill the septal defect are presented.
Surgical bifascicular block.
Authors: Pahlajani D B , Serratto M , Mehta A , Miller R A , Hastreiter A , Rosen K M
Published: June 2012

Electrophysiological studies were performed in 18 patients who developed bifascicular block after repair of ventricular septal defect (VSD) or tetralogy of Fallot (TF). Two had transient complete heart block (CHB) in the immediate postoperative period. The P-A intervals were normal in all. A-H and H-V intervals were prolonged in three and four cases, respectively. Atrial pacing at progressively increasing heart rates was performed in 15 patients; two developed type II block distal to the His bundle (H). The effective and functional refractory periods (ERP and FRP) of the atrium (11 cases) were normal in all. The ERP of the A-V node (seven cases) was prolonged in found and the FRP was increased in three. The ERP of the ventricular specialized conduction system was measured in two cases and was prolonged in one. In all, seven cases had abnormalities indicating disease of the A-V node and/or His-Purkinje system. Recording of intervals, atrial pacing, and determination of refractory periods (RPs) was necessary to reveal all conduction abnormalities. One patient died of unrelated causes. The others are alive and in sinus rhythm with intact conduction 3 to 16.5 years following surgery (mean follow-up of 8.3 plus or minus 0.95 years). The clinical course in patients with normal and abnormal findings was equally benign. Prophylactic insertion of demand pacemakers does not appear indicated in these patients.
Operative treatment in hypertrophic subaortic stenosis. Techniques, and the results of pre and postoperative assessments in 83 patients.
Authors: Morrow A G , Reitz B A , Epstein S E , Henry W L , Conkle D M , Itscoitz S B , Redwood D R
Published: June 2012

The results of operative treatment in 83 patients with idiopathic hypertrophic subaortic stenosis (IHSS) are described. Most patients with the disease are asymptomatic, or derive satisfactory symptomatic improvement from nonoperative therapy: administration of propranolol, exerice limitation, control of arrhythmia, etc. Operation is required, however, in 10-15% of patients, those who remain severely symptomatic after nonoperative treatment or who become refractory to it. Operation relieves symptoms in IHSS by relieving obstruction to left ventricular outflow, and for a patient to be considered an operative candidate severe obstruction must be documented at left heart catheterization either under resting conditions or after provocative interventions. All 83 patients were severely incapacitated--58 in Class III and 24 in Class IV. Seventy had obstruction at rest (average gradient 96 mm Hg), and 13 had only provocable obstruction. At operation the hypertrophic interventricular septum was exposed via an aortotomy, and a vertical bar of muscle was resected between parallel myotomy incisions. There were six operative deaths (7%); no patient has died since 1970. Seven patients have died late after operation, five of them from causes unrelated to their heart disease or the operation. All surviving patients describe symptomatic improvement. Fifty-two patients with obstruction at rest preoperatively (average gradient 95 mm Hg) have been studied postoperatively: no resting gradient was evident in 47, while in the remaining five the gradient was less than 25 mm Hg. Recurrence of obstruction has never been observed at late catheterization (21 pts) or late echocardiographic examination (37 pts). Obstruction could not be provoked postoperatively in ten of the 11 patients who had large gradients only with the Valsalva maneuver or isoproterenol administration preoperatively. Obstructed and provocable obstructed patients had similar symptomatic improvement after operation. A variety of rhythm and conduction abnormalities were observed both pre and postoperatively, and these are described in detail. The results of operation in these 83 patients with IHSS demonstrate that gratifying symptomatic and hemodynamic improvement uniformly follows left ventriculomyotomy and myectomy. Relief of obstruction and amelioration of symptoms have proved to be long-lasting during postoperative observation periods extending to 14 years. Continued application of the operative procedure in properly selected patients appears to be indicated.
Analysis of components in a cardiogenic hypertensive chemoreflex.
Authors: James T N , Isobe J H , Urthaler F
Published: June 2012

A cardiogenic hypertensive chemoreflex was studied in 38 anesthetized and three unanesthetized dogs. Serotonin (100 mug/ml) injected into either the left atrium or small brancehes of the proximal left coronary artery produced a maximal response, with 96 +/- 18 mm Hg increment in mean aortic pressure within 6 +/- 2 seconds, lasting about 1 min; a later phase of the same hypertension lasted 9 +/- 5 minutes more and could partially be produced with serotonin injected into the thoracic aorta. Injections into the distal left coronary artery produced only the Bezold-Jarisch reflex. Concomitant with the immediate hypertension there were vagal and sympathetic efferent effects in both the sinus node and the atrioventricular (A-V) junction. Either of these effects could be selectively eliminated and the other augmented by direct local perfusion with an appropriate cholinergic (atropine 10 mug/ml) or adrenergic beta-receptor (propranolol 10 mug/ml) blocking agent. Bilateral vagotomy markedly attenuated but did not eliminate the acute hypertension, but it abolished both chronotropic and dromotropic effects. Phentolamine (2 mg/min i.v.) markedly diminished the hypertensive response. Guanethidine or reserpine pretreatment markedly diminished the hypertensive response; reserpine eliminated the electrophsiologic effects but guanethidine did not. Infiltration of serotonin around the main left coronary partially reproduced the reflex, but similar infiltration of xylocaine hydrochloride blocked the reflex. Serial section histologic studies of the region around the main left coronary atery in seven dog hearts and nine human hearts demonstrated the presence of a small structure resembling a chemoreceptor; its blood supply originated from the left coronary artery. Some possible clinical implications are discussed.
Electrophysiologic and pathologic correlations in two cases of chronic second degree atrioventricular block with left bundle branch block.
Authors: Bharati S , Lev M , Dhingra R C , Chuquimia R , Towne W D , Rosen K M
Published: June 2012

This study concerns two cases of chronic 2 degrees atrioventricular (A-V) block with left bundle branch block (LBBB). Pathological studies included serial section of the conduction systems. Case 1 had type I 2 degrees block with LBBB. Electrophysiological studies revealed type I 2 degrees block proximal to the His bundle recording site and a prolonged H-V interval (60 msec). Pathologically there was a moderate to marked fibrosis of the approaches to the A-V node and of the A-V node, marked fibrosis of the left bundle branch, and moderate involvement of the right bundle branch. The changes proximal to the His bundle were more marked than the changes distal to this bundle. Case 2 had type II and 2:1 2 degrees A-V block with LBBB. Electrophysiologically the site of block was distal to the His bundle recording site, and there was a prolonged A-V node and severe involvement of both bundle branches. The changes distal to the His bundle were more severe than the changes proximal to the His bundle. This study reveals that the electrophysiologic data more closely approximated the pathologic findings than did surface electrocardiographic data alone. It also emphasizes that there may be multiple sites of disease in chronic 2 degrees block with bundle branch block.
Mitral valve prolapse and coronary artery disease. Clinical, hemodynamic, and angiographic correlations.
Authors: Aranda J M , Befeler B , Lazzara R , Embi A , Machado H
Published: June 2012

Among 95 patients with angina pectoris and angiographically documented coronary artery disease (CAD), prolapse of the scallops of the posterior leaflet of the mitral valve (PLMV) was noted in 30 patients. Left ventriculograms in the right anterior oblique (RAO) projection revealed isolated prolapse of the posteromedial commissural scallop (PMCS) in 12 patients and the anterolateral commissural scallop (ALCS) in two patients. Seven patients had prolapse of both PMCS and ALCS, three had prolapse of the PMCS and middle scallop (MS), and six had prolapse of all three scallops of the PLMV. Left ventricular dilatation with increase trabeculations was observed in 19 patients. Contractility determined in a quantitative fashion by segmental motion analysis was markedly impaired in 29 patients. None of the patients had angiographic evidence of mitral insufficiency. Left ventricular dysfunction was documented in 28 patients by either elevated left ventricular end-diastolic pressure (LVEDP), low cardiac index (CI) or decreased ejection fraction (EF). In two patients in whom left ventricular contractility improved after aortocoronary by pass, previously prolapsed scallops could not be identified in the postoperative ventriculogram. Prolapsed PLMV is a frequent angiographic finding in patients with angiographically observed CAD. Impaired contractility of the ventricular myocardium and papillary muscles, left ventricular dilatation, and hypertrophy appear to play a significant role in the pathogenesis of this abnormality through distortion of the directional axis of the papillary muscles, asynergic contraction of the related free wall of the left ventricle, and changes in the normal spatial alignment necessary for mitral valve closure. The syndrome of papillary muscle dysfunction in patients with coronary artery disease represents a wider clinical spectrom than previously described.
Reduction of infarct size by oxygen inhalation following acute coronary occlusion.
Authors: Maroko P R , Radvany P , Braunwald E , Hale S L
Published: June 2012

This study was carried out in order to determine the effects of the inspiration of O2-enriched air on the size of myocardial infarction. In 15 anesthetized dogs, epicardial electrograms were recorded from 10 to 14 sites on the anterior surface of the left ventricle before and after intermittent occlusion of the left anterior descending coronary artery or one of its major branches. In each dog, one occlusion was carried out while the fraction of inspired oxygen (FIO2) was 0.20 and the other while the FIO2 was 0.40. With an FIO2 of 0.20 the average ST-segment elevation (ST) was 4.0 +/- 0.6 mV (SEM) and the number of sites exhibiting ST-segment elevations exceeding 2 mV (NST) 15 minutes following occlusion was 6.2 +/- 0.7 sites; comparable values following occlusion with an FIO2 of 0.40 were 1.8 +/- 0.4 mV (P less than 0.01) and 2.7 +/- 0.7 sites (P less than 0;01), reflecting reduction in acute myocardial ischemic injury; An FIO2 of 1.0 did not decrease myocardial injury further. In 24 other dogs, occlusion was maintained for 24 hours. In nine dogs in which FIO2 was increased from 0.20 to 0.40 30 minutes after occlusion, myocardial creatine phosphokinase activity (CPK) was less depressed in sites having comparable levels of ST-segment elevation at 15 minutes than in dogs that respired an FIO2 of 0.20 during the entire 24 hours. All (54) sites with ST-segment elevations greater than 3 mV in the 0.20 FIO2 group showed early signs of myocardial infarction, while only 49% of such specimens showed infarction in the 0.40 FIO2 group. Thus it is concluded that 0.40 FIO2 following an experimental coronary artery occusion decreases acute ischemic injury and reduces the eventual development of necrosis, as evaluated by enzymatic and histological techniques.
Prognosis in medically-treated coronary artery disease: influence of ejection fraction compared to other parameters.
Authors: Nelson G R , Cohn P F , Gorlin R
Published: June 2012

The prognostic value of the left ventricular ejection fraction(EF) was compared to that of other commonly used indices--severity of coronary artery disease, left ventricular end-diastolic pressure, cardiac index, and abnormal ECG--in 144 patients with coronary artery disease followed for an average of 14 months on medical management. During this period, 14 patients (10%) died. Analysis of the mortality demonstrated that the EF was the most powerful predictor of short-term survival. Thus, patients with three-vessel coronary artery disease and anormal EF (greater than 0.50) had a significantly lower mortality (12%) than did patients with three-vessel CAD and a reduced EF (33%, P less than 0.001). Similar comparisons were observed within the subgroups with abnormal hemodynamics or an abnormal ECG. Therefore, the EF appears to be an important prognostic guide in the medical therapy of coronary artery disease, and is of significantly more discriminant value than other measurements when combined abnormalities exist.
P waves during ectopic atrial rhythms in man: a study utilizing atrial pacing with fixed electrodes.
Authors: MacLean W A , Karp R B , Kouchoukos N T , James T N , Waldo A L
Published: June 2012

Threshold bipolar pacing was performed from one of 12 selected atrial sites with temporary implanted electrodes in 69 patients following open-heart surgery in order to study P wave polarity and morphology and the P-R interval during paced ectopic atrial rhythms. A negative P wave was recorded in lead I only with pacing the left atrium and only when pacing near the left pulmonary veins. A positive bifid P wave in V1 was recorded only with left atrial pacing and only when pacing was near the inferior pulmonary veins and coronary sinus. P wave polarity and morphology were otherwise of no use in localization of the origin of the impulse in these studies. The pacing stimulus to P wave interval was found to vary between 10 and 54 msec, making the duration of the P-R interval an unreliable indicator of the site of origin of the paced impulse. Although the relation of these paced rhythms to spontaneously occurring ectopic rhythms is unclear, the previously published criteria for localizing ectopic atrial rhythms are again demonstrated to be unreliable. P wave polarity and morphology and the P-R interval are of limited value in ascertaining the origin of ectopic atrial rhythms in man.
Electrophysiological delineation of the specialized A-V conduction system in patients with corrected transposition of the great vessels and ventricular septal defect.
Authors: Waldo A L , Pacifico A D , Bargeron L M , James T N , Kirklin J W
Published: June 2012

The specialized atrioventricular (A-V) conduction system was electrophysiologically delineated during open-heart surgery in four patients with congenitally corrected transposition of the great vessels and associated ventricular septal defect and one patient with single ventricle. Two consistent observations were made: 1) In no case was the specialized A-V conduction system found in the right atrium, whether or not there was a coronary sinus ostium present. 2) Specialized A-V conduction system electrograms were never delineated posterior to the ventricular septal defect, in contradistinction to this usual location in hearts having ventricular septal defects associated with other congenital lesions. In three of five patients, the initial course of the A-V conduction system of the ventricles was delineated between the anterior aspect of the ventricular septal defect and the pulmonary artery. In one patient the proximal portion of the A-V conduction system was delineated on the anterior aspect of the pulmonary conus. The course and extent of the A-V conduction system delineated in the morphological left ventricle suggests it is a left bundle branch. The surgical implications of the ectopic location of the A-V conduction system anterior to the ventricular septal defect, and the variability of the more proximal portion of the A-V conduction system are discussed.
Effects of clofibrate and sulfinpyrazone on platelet survival time in coronary artery disease.
Authors: Steele P , Battock D , Genton E
Published: June 2012

Platelet survival time was measured (autologous labelling with 51chromium) in 68 men with coronary artery disease (CAD). Survival was shortened slightly (3.2 +/- 0.04 days; mean +/- SEM) as compared to normal (3.7 +/- 0.04 days; N = 18; P less than 0.001), and 60% had shortened survival (less than 3.3 days). Thirty-seven had hyperlipoproteinemia (36 with Type IV and one with Type III) and platelet survival was shortened (3.1 +/- 0.10 days) and significantly different from survival of men with normal lipoproteins (3.3 +/- 0,12 days; P less than 0.05). Twenty-two with shortened platelet survival and CAD received either clofibrate or sulfinpyrazone. Clofibrate prolonged platelet survival (2.6 +/- 0.09 to 3.4 +/- 0,14 days; P less than 0.001) and ten of 12 had prolongation of survival. Sulfinpyrazone increased survival (2.8 +/- 0.12 to 3.6 +/- 0.21; P less than 0.001) and nine of ten had prolognation of platelet survival. Clofibrate lowered serum cholesterol and tryglyceride but alteration in lipids did not correlate with alteration of survival. Sulfinpyrazone did not alter lipids. Data suggest that survival is shortened in CAD and that clofibrate and sulfinpyrazone alter survival. Platelet suppressant agents may prove beneficial in reducing the extent and complications of atherosclerotic arterial injury.
Comparative hemodynamic effects of chewable isosorbide dinitrate and nitroglycerin in patients with congestive heart failure.
Authors: Mikulic E , Franciosa J A , Cohn J N
Published: June 2012

Vasodilators are known to be effective in improving the hemodynamics of congestive heart failure by increasing cardiac output and reducing left ventricular filling pressure (LVFP). Long acting agents are needed to augment the practicality and availability of chronic vasodilator therapy. In the present study the vascular effects of chewable isosorbide dinitrate (CHIS), sublingual nitroglycerin (NTG) and placebo (P) were compared in eight patients with high LVFP due to heart failure. Patients with LVFP (pulmonary wedge pressure) over 14 mm Hg were given CHIS, 10 mg, NTG, 0.6 mg, and P, two chewable tablets, in random fashion. Heart rate (HR), blood pressure (BP) and LVFP were monitored for three hours after each drug. HR was not significantly affected by any drug, although it rose slightly after NTG and fell after CHIS. Significant reduction of BP occurred only after NTG, with peak effect at five minutes, but lasting only 15 minutes. NTG reduced LVFP 5.1 mm Hg (19.5%, P, less than 0.05), at peak effect, but LVFP was no longer significantly lower by 20 minutes after NTG. After CHIS, LVFP fell significantly within five minutes, reached a peak reduction of 8.6 mm Hg (32;7%, P less than 0.01) at 15 minutes, and remained significantly lower through three hours. Thus CHIS provides a nitrate action of rapid onset and sustained effect that may be useful for chronic vasodilator therapy of heart failure.
The postponed compensatory pause as a manifestation of positive feedback in atrioventricular conduction.
Authors: Goldberg L B , Levy M N , Edelstein J
Published: June 2012

A patient with hypertensive cardiovascular disease was found to have unusual varieties of premature atrial and ventricular contractions. If the premature atrial contraction resulted in a greatly prolonged P-R interval, such that the increment in P-R exceeded the decrement in the preceding R-P, the next sinus P wave, occurring after a normal P-P interval, was found to be blocked. Also, numerous interpolated ventricular extrasystoles were observed in which the postextrasystolic P-R intervals were markedly prolonged and in which the compensatory pauses were postponed for one or two beats. We also present data from one dog in which a premature atrial activation produced a chain reaction such that complete A-V block occurred three beats later. We propose that the chain reaction which evoked the delayed block in the dog and the postponed compensatory pauses in the patient reflects the operation of a positive feedback mechanism in A-V conduction. Positive feedback is initiated by an extremely long P-R, which results in a very short R-P before the next cycle. This then leads to a still longer P-R, which then elicits a still shorter R-P. Block ultimately supervenes when the atrial activation wave arrives at the A-V junction during its effective refractory period.
Response of patients and physicians to mass screening for coronary risk factors.
Authors: Aronow W S , Allen W H , De Cristofaro D
Published: June 2012

Qestionnaires were sent to 1,817 adults screened twice for coronary risk factors 10 to 11 months apart and to their physicians. Physician questionnaires returned on 1,764 persons indicated that 359 (20.4%) of the total group and 227 of 1,191 persons (19.1%) with one or more abnormal risk factors during the first screen did not return for follow-up care. Only persons with one or more risk factors were given advice or medication. When the 227 patients that did not return for follow-up are removed from the group with one or more risk factors, the 239 patients who received advice or treatment comprise 24.8% of those who could have been treated. Of the total 1,764 patients, 13.5% recieved treatment or advice. Qestionnaires returned by 1,396 persons who received follow-up care by their physicians confirmed that only those who had one or more risk factors received advice or treatment. Results of the patient questionnaires show that 223 persons received advice or treatment (23.2% of all with risk factors who returned for follow-up; 16.0% of the 1,396 persons). Furthermore, of 116 persons prescribed medication for risk factor control, 60 (51.7%) were not taking this medication. Of 20, persons given advice for reduction of risk factors, 162 (78.9%) were not following this advice. These data indicate physician indifference and patient apathy to reduction of coronary risk factors in asymptomatic individuals.