bluuebunny/crossref_metadata_2025 huggingface dataset:
An ultrastructural basis for electrocardiographic alterations associated with Duchenne's progressive muscular dystrophy.
Authors: Sanyal S K , Johnson W W , Thapar M K , Pitner S E
Published: June 2012

Electrocardiographic abnormalities were identified in 63 (84%) of 75 patients with Duchenne's progressive muscular dystrophy. A tall R wave over V1 with an abnormal R/S ratio was seen in 64% of the patients, a deep and narrow Q wave greater than 4 mm over leads I, V5, and V6 in 44%, sinus tachycardia in 32% and right axis deviation in 16%. Other ECG abnormalities included an abnormal PV1 index in 14% of patients and a short P-R interval in 6%. Ultrastructural characteristics of the heart were determined for two patients with characteristic electrocardiographic abnormalities. Common to both hearts was a total loss of thick as well as thin myofilaments, which gave a "moth-eaten" appearance to the myofiber. This feature, combined with preservation of the transverse tubular system, formed the most characteristic ultrastructural finding and was seen most consistently in the posterobasal area of the left ventricle. Alterations of Z-band material; accumulation of mitochondria, occasionally containing electron-dense bodies and showing loss or discontinuity of cristae; dilatation of sarcoplasmic reticulum with striking ectasia of cisternae; depletion of glycogen particles; a paucity of lipoid or lipochrome granules; and the absence of virus-like particles were other consistent ultrastructural features. Comparison of skeletal and cardiac muscle disclosed identical subcellular changes. These observations support the contention that the distinctive ECG pattern associated with Duchenne's dystrophy results from multifocal degenerative changes involving myocardium, predominantly the posterobasal region of the left ventricle and the posterior papillary muscle.
Echocardiographic diagnosis of left ventricular hypertrophy.
Authors: McFarland T M , Alam M , Goldstein S , Pickard S D , Stein P D
Published: June 2012

Echocardiograms were obtained on 27 adults with electrocardiographic criteria of left ventricular hypertrophy (LVH) to determine how echocardiograms might best identify LVH. Both the left ventricular (LV) posterior wall thickness and interventricular septal thickness were found by echocardiography to be increased (greater than or equal to 12 mm) in only 13 of 27 patients (48%) with LVH. The LV was dilated (greater than or equal to 58 mm) in the absence of posterior wall thickening in 9 of 27 patients (33%). The LV mass, estimated from standardly measured dimensions, was increased (greater than 200 g) in 21 of 27 patients (78%) and when measurements were made by the Penn method, mas was increased in all patients. These observations indicate that the echocardiographic estimation of LV mass is a more sensitive indicator of LVH than LV posterior wall and septal thickness. Since LVH is defined as an increased mass of LV muscle, these observations are consistent with this fundamental definition of left ventricular hypertrophy.
Echocardiographic estimation of pulmonary artery pressure in transposition of the great arteries.
Authors: Gutgesell H P
Published: June 2012

To determine their usefulness in estimating pulmonary artery pressure, left ventricular systolic time intervals (STI) were determined by echocardiography in 65 patients with dextro-transposition of the great arteries (TGA). The STI were measured from recordings of pulmonary valve motion at 100 mm/sec paper speed. The pre-ejection period (PEP) and the ratio of PEP to left ventricular ejection time (PEP/LVET) were directly related to pulmonary artery pressure. The strongest correlations were that between PEP/LVET and pulmonary artery diastolic pressure (r = 0.70) and that between PEP/LVET and the ratio of mean pulmonary pressure to mean systemic pressure (r = 0.71). A value of PEP/LVET of less than 0.26 was consistently associated with pulmonary artery diastolic pressures of less than 20 mm Hg and, in 28 of 31 patients, pulmonary artery pressure less than one-third of mean systemic arterial pressure. Pulmonary hypertension was present in 18 of 22 patients with PEP/LVET of 0.30 or greater; elevated PEP/LVET was also present in four patients with abnormalities of cardiac rhythm or conduction, two of whom also had angiographic evidence of myocardial dysfunction.
Echocardiographic features of the interventricular septum in chronic constrictive pericarditis.
Authors: Candell-Riera J , García del Castillo H , Permanyer-Miralda G , Soler-Soler J
Published: June 2012

Echocardiographic characteristics of the interventricular septum (IVS) have been studied in eight patients with chronic constrictive pericarditis (CP). Values of septal thickening (ST) were clearly below normal in all cases. Interventricular septal systolic motion (IVSSM) was normal in four cases, hypokinetic in three and paradoxical in one. In seven out of the eight patients, an early interventricular septal diastolic motion (IVSDM) consisting of a sudden anterior displacement followed by a brisk posterior rebound was recorded. The beginning of this anomalous movement was coincident with the pericardial knock in the phonocardiogram and its peak was coincident with the simultaneously recorded deep "y" trough in the jugular pulse tracing. The tendency toward normality of IVSDM observed after pericardiectomy in six out of seven patients suggests that this peculiar interventricular septal systolic motion may be a frequent and probably specific echocardiographic finding in constrictive pericarditis.
Effect of digoxin and diuretics on high altitude left ventricular dysfunction.
Authors: Balasubramanian V , Behl A , Das G S , Wadhwa A K , Mathew O P , Hoon R S
Published: June 2012

Systolic time intervals, stroke volume, cardiac output and (dZ/dt)/RZ index were serially estimated in 51 normal healthy volunteers at sea level, for ten days after air induction to 3658 m altitude and on return to sea level. The subjects were divided into three groups and were administered a diuretic, beta methyldigoxin and placebo in a double blind protocol. The group on placebo showed an increase in heart rate, reduction in stroke index and cardiac index during high altitude exposure with normalization on return to sea level. A deterioration in left ventricular function as manifested by prolongation of pre-ejection period, increase in PEP/LVET ratio, reduction in (dZ/dt)/RZ index and left ventricular ejection time was also noted at high altitude. The subjects on digoxin maintained normal stroke/cardiac index and did not show any significant changes in the parameters of myocardial function. The diuretic group showed more deterioration in the parameters than the placebo group. No significant side effects were noted. Left ventricular dysfunction and reduction of stroke index at high altitudes may be causually related; digoxin administration may prevent them from occurring.
Pulmonary hemodynamics and right ventricular function in hypertension.
Authors: Olivari M T , Fiorentini C , Polese A , Guazzi M D
Published: June 2012

Pulmonary and systemic hemodynamics in 16 hypertensive subjects (group I) with left ventricular (LV) hypertrophy (ECG and echo criteria) and in 17 hypertensive subjects with ECG signs of LV strain (group II), were compared with those in 14 normal individuals. An augmented pulmonary arteriolar resistance (PAR) in group I and to a larger extent in group II accounted for the pulmonary pressure elevation in both groups. Increase in PAR was unrelated to pulmonary blood flow and volume, pleural pressure, arterial PO2, PCO2 and pH, and could not be explained entirely by the left ventricular end-diastolic pressure changes. In group I, left (L.MSEJR) and right (R;MSEJR) mean systolic ejection rate, stroke index (SI) and mean velocity of circumferential fiber shortening (VCF) were enhanced in spite of the heightened pressure load on both sides of the heart. In group II, a large reduction of SI, L.MS.EJR, R.MSEJR and VCF, as well as the relationship between ventricular filling pressures and SI, documented a compromised performance of both ventricles, Findings indicate that: systemic hypertension is associated with elevation of pulmonary arterial pressure and of PAR which is not necessarily a consequence of impairment in LV function; LV hypertrophy is associated with enhanced performance of either ventricle; in coincidence with development of ECG signs of LV strain, the performance of both sides of the heart deteriorates. A functional interdependence of the two ventricles is suggested.
Alteration of the left ventricular diastolic pressure-segment length relation produced by the pericardium. Effects of cardiac distension and afterload reduction in conscious dogs.
Authors: Shirato K , Shabetai R , Bhargava V , Franklin D , Ross J
Published: June 2012

Left ventricular pressure and segment length were measured in seven conscious chronically instrumented dogs with the pericardium intact and 3-9 days after pericardiectomy. Diastolic pressure-length plots were obtained under control conditions and after acute volume loading followed by sodium nitroprusside infusion. In all dogs with intact pericardium, volume loading displaced the entire diastolic pressure-length curve upwards and sodium nitroprusside shifted it toward control. After pericardiectomy the pressure-segment length data during control, volume loading and sodium nitroprusside fell on a single curve (intercepts and slopes not statistically different); After dextran infusion, intrapericardial pressure rose from control 1.5 +/- 0.7 mm Hg to 8.2 +/- 0.5 mm Hg, and it fell to 4.8 +/- 0.1 mm Hg after nitroprusside. Therefore, in acute cardiac dilatation the pericardium contributed significantly to the increased left ventricular diastolic pressure and to the fall during sodium nitroprusside infusion and appeared responsible for shifts in the diastolic pressure-segment length relation.
Long-term clinical course and symptomatic status of patients after operation for hypertrophic subaortic stenosis.
Authors: Maron B J , Merrill W H , Freier P A , Kent K M , Epstein S E , Morrow A G
Published: June 2012

Long-term results of operation for IHSS were reviewed in 124 patients operated upon between 1960 and 1975. Most patients improved symptomatically and manifested marked reduction in LV outflow gradient at rest postoperatively. However, ten (8%) patients died of causes related to operation, 14 (12%) had persistent or recurrent severe functional limitation, and 11 (9%) died up to 13 years postoperatively due to hypertrophic cardiomyopathy. Overall annual mortality rate was 3.5% and was 1.8% for late deaths alone. Of 11 late postoperative deaths, six were sudden and five were due to chronic heart failure. Atrial fibrillation was significantly more common in patients who died late postoperatively than in survivors. Nine of the 11 late deaths had associated medical problems that may have contributed to their outcome. In conclusion, long-lasting clinical improvement occurred in most patients who survived operation for IHSS. However, 12% of patients deteriorated clinically over the 5.2 year average follow-up, and there is continued, small annual mortality.
Use of time interval histographic output from echo-Doppler to detect left-to-right atrial shunts.
Authors: Goldberg S J , Areias J C , Spitaels S E , de Villeneuve V H
Published: June 2012

The primary purpose of this study was to attempt to select, by examination of the time interval histogram (TIH) output of a range gated pulsed Doppler (RGPD), all children with left-to-right shunt at the atrial level from a pool of 57 children. Fifty-four of the children had various forms of acyanostic cardiac disease. A secondary purpose was to identify any associated lesions in those children with atrial defects. Examiners were unfamiliar with the children and their diagnoses. Results were interpreted independently by two examiners. Detection of diastolic TIH dispersion was used when studying the right atrial outflow tract to separate children with atrial left-to-right shunts from control children. All controls were judged negative by this technique, and 13 of 14 children with atrial shunts were detected by both examiners; the 14th was detected by one examiner. Of a total of 308 TIH decisions on the atrial shunt group, 298 were made identically by both examiners for a 97.7% agreement, demonstrating the objectivity of the method. This study demonstrated the usefulness of the TIH evaluation, indicating that continued investigation and equipment improvements are warranted.
The problem of valve prosthesis-patient mismatch.
Authors: Rahimtoola S H
Published: June 2012

Valve prostheses have played an important part in the past two decades in the management of patients with valvular heart disease. However, many of the devices used in valve replacement have introduced new clinical problems. This paper deals with some of the problems associated with valve replacement, including one not previously emphasized--valve prosthesis-patient mismatch, which may cause obstruction to ventricular outflow and/or inflow.
A case-control study of regular aspirin use and coronary deaths.
Authors: Hennekens C H , Karlson L K , Rosner B
Published: June 2012

Information was collected for a large number of coronary risk factors on a series of 568 married, white men, aged 30--70 years, who died from coronary heart disease. Information on the same risk factors was collected on an equal number of living controls matched on age, sex, marital status and neighborhood. For regular aspirin users (i.e. greater than or equal to 4 days per week) compared with non-users, the crude matched pair risk ratio estimate was 1.0 (95% confidence limits 0.9--1.1). Even after controlling for possible confounding effects of other variables using a paired multiple logistic regression analysis, there was no evidence of association. These data provide no evidence for a preventive role of regular aspirin intake in coronary deaths.
The Björk-Shiley aortic prosthesis: flow characteristics, thrombus formation and tissue overgrowth.
Authors: Yoganathan A P , Corcoran W H , Harrison E C , Carl J R
Published: June 2012

Thrombus formation and tissue overgrowth were observed in nine Björk-Shiley aortic prostheses recovered six months or longer after implantation. These pathologic findings may be attributed to the flow characteristics of the prosthesis. The open disc of the valve separates the flow into two unequal regions. Varying degrees of thrombus formation were observed in the minor outflow region, including the depression in the aortic face of the disc and the metal strut bridging this area. Tissue overgrowth was noted along the perimeter of the prosthesis adjacent to the minor outflow region. That overgrowth further reduced the available cross section for flow in this already constrained area. In vitro velocity measurements with a laser-Doppler anemometer identified a zone of stagnation about 20 mm wide near the aortic face of the disc. The average velocities in the major and minor outflow regions were around 100 and 25 cm/sec, respectively, and the corresponding peak-shear stresses were approximately 700 and 150 dynes/cm2. There is reason, then, to attribute the thrombus formation and tissue overgrowth to the stagnation zone and the low shear in the minor outflow region.
Myocardial infarct quantification in the dog by single photon emission computed tomography.
Authors: Keyes J W , Leonard P F , Brody S L , Svetkoff D J , Rogers W L , Lucchesi B R
Published: June 2012

Radionuclide techniques for sizing acute myocardial infarction have been hampered by the intrinsic limitations of the scintillation camera. Emission computed tomography can overcome these limitations. Single photon emission computed tomograms of the distribution of technetium-99m pyrophosphate in acute anterior and posterior infarcts were obtained in 16 dogs after death. Tomograms were also obtained in 10 dogs during life without gating. The size of the infarcts was determined by staining gross sections of the heart with nitro blue tetrazolium, dissecting out the infarcted tissue and weighing it. Infarct sizes were determined from the tomographic images and compared with the measured infarct sizes. Good images showing the location and three-dimensional extent of the infarcts were obtained in all dogs. The measured and calculated infarct sizes correlated well (r = 0.85). Comparison of the calculated sizes in the living (non-gated) and dead ("physiologically" gated) animals showed reasonable agreement (r = 0.87). Single photon emission computed tomography is a feasible and useful technique for localizing and sizing acute myocardial infarctions.
Beneficial effects of hydralazine in severe mitral regurgitation.
Authors: Greenberg B H , Massie B M , Brundage B H , Botvinick E H , Parmley W W , Chatterjee K
Published: June 2012

The severity of mitral regurgitation is, in part, determined by aortic impedance to left ventricular outflow. Sodium nitroprusside acutely decreases regurgitant flow, but the importance of its dual vasodilating effects, the lowering of peripheral vascular resistance and increasing of venous capacitance, is unclear. We studied the hemodynamic response to intravenous hydralazine, which selectively acts on the arteriolar resistance bed, in 10 patients with severe mitral regurgitation. Hydralazine produced a 50% increase in forward stroke volume (22 +/- 2 to 33 +/- 3 ml/m2, P less than 0.001) and a 33% reduction in regurgitant stroke volume (40 +/- 6 to 27 +/- 6 ml/m2, P less than 0.001), with a resultant fall in pulmonary capillary wedge v wave and mean pressures. Unlike nitroprusside, it did not alter left ventricular end-diastolic volume or pressure. Oral hydralazine maintained this hemodynamic improvement for at least 48 hours and, in three patients, provided more sustained clinical improvement. We conclude that hydralazine, by virtue of its selective lowering of aortic impedance, reduces the amount of mitral regurgitation and thus may be a useful mode of interim or chronic therapy in selected patients.
Limitations of routine long-term electrocardiographic monitoring to assess ventricular ectopic frequency.
Authors: Morganroth J , Michelson E L , Horowitz L N , Josephson M E , Pearlman A S , Dunkman W B
Published: June 2012

Variations in the frequency of ventricular premature depolarizations (VPDs) were evaluated with three consecutive 24-hour long-term electrocardiography monitor recordings from 15 clinically stable patients with various cardiac disorders. Mean hourly VPD frequencies ranged from 37--1,801 per hour. Data were subjected to 4 and 5 factor nested analyses of variance. The extent of spontaneous variation in arrhythmia frequency that occurred in individual patients from day to day was 23%, between 8-hour periods within days was 29%, and from hour to hour was 48%. In addition, the variability between repeated three-day monitoring periods over time was quantified in five patients and found to be 37%. This analysis determined that to distinguish a reduction in VPD frequency attributable to therapeutic intervention rather than biologic or spontaneous variation alone required a greater than 83% reduction in VPD frequency if only two-24-hour monitoring periods were compared, and greater than 65% reduction if two 72-hour periods were compared. The limitations of routine 24-hour electrocardiographic monitoring must be considered in diagnostic and therapeutic decision-making.
Aortic input impedance in heart failure.
Authors: Pepine C J , Nichols W W , Conti C R
Published: June 2012

The input impedance of the systemic circulation was calculated from recordings of pulsatile pressure and flow in the ascending aorta of 20 patients. Ten patients had clinical and hemodynamic evidence of heart failure. The other 10 subjects had no clinical evidence of heart failure and were used as a control group. In the heart failure patients, both input resistance and characteristic impedance (index of aortic distensibility) were significantly increased compared to pressure- and age-matched control subjects. Oscillations of impedance moduli, represented by the difference between maximum and minimum moduli, were also significantly increased in the heart failure patients compared with the control subjects. The increased characteristic input impedance in these heart failure patients suggests that the human aorta is stiffer in heart failure, and the larger oscillations in the impedance spectrum indicate an increase in pressure and flow wave reflections. From reflected wave theory in elastic tubes, reflected pressure waves add to the amplitude of incident pressure waves at the entrance of the system, whereas reflected flow waves subtract from the magnitude of the forward flow. Thus, changes in aortic distensibility could have an important influence on the pulsatile function of the failing left ventricle.
Alterations in calcium levels of coronary sinus blood during coronary arteriography in the dog.
Authors: Higgins C B , Schmidt W
Published: June 2012

Intracoronary administration of contrast materials causes myocardial depression which is related to serveral physiochemical properties of the contrast solution. The role of variations in ambient calcium ions (Ca++) in mediating this effect was evaluated in 19 anesthetized dogs. Sodium meglumine diatrizoate caused decreases in left ventricular peak systolic pressure (LVPSP),-12.6 +/- 3.2%, and dp/dt at a left ventricular pressure (LVP) of 40 mm Hg, -14.3 +/- 4.1%. The total calcium (Cat) decreased from 10.2 +/- 0.2 to 6.5 +/- 0.2 mg%, while Ca++ decreased from 4.6 +/- 0.1 mg% to 2.3 +/- 0.7 mg%. In the presence of systemic hypocalcemia the myocardial depressant actions of this contrast materials were accentuated. Intracoronary administration of contrast material with added Ca++, calcium sodium meglumine metrizoate, caused no myocardial depression. Total calcium decreased only slightly (10.2 +/- 0.2 to 9.1 +/- 0.2 mg%), while Ca++ increased (4.8 +/- 0.1 to 5.1 +/- 0.2 mg%. During systemic hypocalcemia, the calcium metrizoate compound induced increases in LVPSP and dp/dt/LBP40. Thus, contrast materials caused myocardial depression which, at least in part, was related to reduction of ambient calcium through a dilutional and binding action. The addition of Ca++ to monomeric contrast materials reversed the myocardial depressant action and produced a transient rise in ambient Ca++.
Echocardiography of left ventricular masses.
Authors: Ports T A , Cogan J , Schiller N B , Rapaport E
Published: June 2012

The M-mode and two-dimensinal real-time echocardiographic findings in 10 patients with left ventricular masses are discussed. Two patients had left ventricular tumors and eight had left ventricular thrombi. In all cases the diagnosis was confirmed by angiography or surgery. The intracavitary and intramural left ventricular tumors were detected both by M-mode and two-dimensional echocardiography . M-mode echocardiography, however, did not detect the left ventricular thrombus in all instances. Two-dimensional echocardiography was able to identify the four large and inhomogeneous left ventricular thrombi but did not clearly identify four cases of smaller mural thrombi. Echocardiography techniques useful in detection of left ventricular masses are discussed.
Clinical use of blade atrial septostomy.
Authors: Park S C , Neches W H , Zuberbuhler J R , Lenox C C , Mathews R A , Fricker F J , Zoltun R A
Published: June 2012

A cardiac catheter enclosing an extensible blade was used to enlarge the interatrial opening in seven patients. Two patients with transposition of the great arteries who had balloon atrial septostomy as newborns subsequently presented with clinical evidence of a restrictive interatrial opening at 1 and 4 months of age. Cardiac catheterization confirmed restenosis of the interatrial opening and inadequate intracardiac mixing. After blade atrial septostomy the systemic arterial oxygen saturation increased by 20% and 30%, respectively. Five patients with mitral atresia complex, ages 2 months-9 1/2 years, had a restrictive interatrial communication and severe pulmonary venous hypertension (mean left atrial pressures ranged from 20-38 mm Hg). Following blade atrial septostomy, the pressure gradient between the atria was almost completely abolished and prompt clinical improvement was observed in each patient. All patients tolerated the procedure without complications. Blade atrial septostomy was a safe, effective procedure for enlarging the interatrial communication in this limited series of patients with an interatrial septum too thick to permit adequate rupture by conventional balloon atrial septostomy.
Tracking of blood lipids and blood pressures in school age children: the Muscatine study.
Authors: Clarke W R , Schrott H G , Leaverton P E , Connor W E , Lauer R M
Published: June 2012

In four cross sectional school screens, the Muscatine Study has sampled 8,909 school children; 820 have been studied repeatedly over a six-year period. Tracking of measurements described by the relationship between repeated observations and the relationship between peer rank orderings over the six-year period has been studied. For height and weight, correlations between observations six years apart were approximately 0.74 and about 60% of children initially in the upper quintile were there again six years later. Six-year correlations were 0.65 for skinfold and 0.61 for cholesterol. Four-year correlation for fasting triglyceride was 0.40. Six-year correlations were 0.30 for casual systolic blood pressure and 0.18 for diastolic blood pressure. Peer rank orderings for both blood pressures were highly variable. Height and weight track well, and thus routine measurement of these variables are useful in identifying children with growth perturbing disorders. Cholesterol and, to a lesser degree, triglycerides also track, and a significant proportion of children with initially high values demonstrated consistently high values throughout the study period. Blood pressures do not track as well; consistently high blood pressures are unusual, thus indicating the need for repeated blood pressure measurements to identify children with persistent elevated levels. The future significance of transient blood pressure elevations has yet to be established.
Beneficial actions of N-dimethyl propranolol on myocardial oxygen balance and transmural perfusion gradients distal to a severe coronary artery stenosis in the canine heart.
Authors: Gross G J , Warltier D C , Hardman H F
Published: June 2012

The purpose of the present study was to compare the effects of N-dimethyl propranolol (DMP), the quaternary derivative of propranolol, and propranolol on the transmural distribution (endo/epi) of coronary blood flow in normal and ischemic regions of the myocardium. The distribution of blood flow between subendocardium and subepicardium of a nonischemic region and one distal to a severe left circumflex coronary artery stenosis was determined by use of tracer microspheres (15 microgram) in intact dog hearts. DMP (1,5 and 10 mg/kg I.V.) produced a small dose-related increase in endo/epi of the nonischemic region (1.15 +/- 0.04--1.24 +/- 0.05), whereas a larger increase was observed in the ischemic region (0.61 +/- 0.08--1.09 +/- 0.10). DMP also produced a significant increase in ischemic subendocardial blood flow (0.59 +/- 0.12--0.76 +/- 0.11 ml/min/g). Similarly, propranolol (0.5 and 1.0 mg/kg I.V.) produced a small increase in endo/epi of the nonischemic region (1.18 +/- 0.08--1.30 +/- 0.07) and a larger increase in the ischemic region (0.72 +/- 0.17--1.18 +/- 0.09). However, propranolol did not increase ischemic subendocardial blood flow. It is concluded that DMP may be an alternative to propranolol in certain types of acute myocardial ischemia when beta-adrenergic blockade is undesirable.
Electrophysiologic effects of partial coronary flow reduction in the exposed canine heart. Effects of ischemia and ischemic-induced regional hypothermia on refractoriness and conduction delay.
Authors: Daniel W G , Svenson R H , Masters T N , Robicsek F
Published: June 2012

In the open-chested dog, coronary flow reduction results in a decrese of regional myocardial temperature (T). We assessed the contribution of T decrease to changes in refractoriness and conduction delay attributed to ischemia. The independent effect of regional hypothermia on effective refractory period (ERP) was a linear function of the temperature (ERP = -b T +a) with a -r = 0.97 0.02 in 11 dogs. The effect on conduction time of a ventricular premature beat was a linear function of the dog T at both endocardium (-r = 0.95 +/- 0.02) and epicardium (-r = 0.96 +/- 0.01). A 75% reduction in coronary flow resulted in a mean T decrease of 1.0 +/- 0.3 degrees C. The T decrease was sufficient to mask the effects of ischemia on shortening of the ERP. Furthermore, the conduction delay of ventricular premature beats during 75% coronary flow reduction could be accounted for by the decrease in T alone in five of seven dogs. We conclude that changes in refractoriness and conduction during acute coronary flow reduction in the open-chested dog are due to the composite effects of ischemia and the decrease in regional temperature. The open-chested model may have important limitations in understanding the electrophysiologic effects of acute coronary insufficiency. However, it may have important applications in defining the electrophysiologic environment at the time of coronary artery surgery.
Mechanisms of ventricular parasystole.
Authors: Kinoshita S
Published: June 2012

Eight cases of ventricular parasystole are reported. In all these cases, regardless of whether parasystole seems intermittent or "continuous," the presence of second degree entrance block of the Mobitz type I was suggested. Parasystole alternated with concealed extrasystolic bigeminy showing occasional reentrant extrasystoles. Such intermittent parasystole appears to originate in the reentrant path of extrasystoles. Reentrant extrasystolic bigeminy was seen in a comparatively rapid sinus rhythm, whereas parasystolic bigeminy was seen in a comparatively slow sinus rhythm. The difference between the interectopic intervals during parasystolic bigeminy and during (manifest or concealed) extrasystolic bigeminy was comparatively small so that occasionally the difference was not distinct; on such an occasion the case showed a seemingly "continuous" parasystole. These observations strongly suggest the possibility that most cases of parasystole, whether intermittent or "continuous," may be governed by incomplete entrance block of the second degree.
Correlation of angiographic and autopsy left ventricular dimensions in children.
Authors: Fisher E A , Eckner F A , DuBrow I W , Hastreiter A R
Published: June 2012

To evaluate controlled pressure coronary artery perfusion fixation of hearts as a means of obtaining meaningful cardiac measurements at autopsy, left ventricular (LV) autopsy measurements were correlated with in vivo end-diastolic (D) and end-systolic (S) angiographic (angio) values from biplane cineangiograms in the same patients. Mitral (MV) and aortic valve (AV) circumferences, LV equatorial circumference (Circ), spatial inflow and outflow lengths, wall thickness (W) and LV volume (Vol) were measured in 34 children with congenital heart disease. All dimensions showed significant correlation of angiographic and autopsy data from which linear regression equations were derived. The r values obtained were: MV 0.74; AV 0.85; D Circ 0.83; S Circ 0.82; D inflow 0.92; S inflow 0.90; D and S outflow 0.96; W 0.78; D Vol 0.92; S Vol 0.86. Mean angio and autopsy values were not significantly different for AV, S inflow, and S Vol. Autopsy values were lower than all D angio values and MV (P less than 0.001 for all), and higher than angio W and S outflow (P less than 0.001 for both). The data show that changes of LV morphology with this fixation method are predictable, making estimation of in vivo values from autopsy measurements possible using the derived linear regression equations.
The genesis of the diastolic murmur of complete heart block. Phono-echocardiographic observations.
Authors: Jelveh M , Berger M , Goldberg E
Published: June 2012

A 72-year-old man with calcific aortic stenosis and complete heart block was noted to have an intermittent diastolic murmur. Using combined echocardiography and phonocardiography, it was demonstrated that the murmur occurred while the mitral valve was closing. This suggested that antegrade flow across a closing mitral orifice is of etiologic importance in the production of the murmur. Atrial sounds were also recorded and probably have a similar etiology. It is postulated that reduced ventricular compliance resulting in a more rapid rate of mitral valve closure was of etiologic importance in the genesis of the murmur.
Platelet aggregation in aortic and coronary venous blood in patients with and without coronary disease. 3. Role of tachycardia stress and propranolol.
Authors: Mehta J , Mehta P , Pepine C J
Published: June 2012

We studied 16 patients with coronary artery disease (CAD) to evaluate platelet aggregation in blood samples withdrawn simultaneously from the aorta and coronary sinus. At rest, mean platelet aggregation in coronary venous blood was significantly lower than that in aortic blood. Platelet counts in coronary venous blood were also lower than in the aortic blood in each of the six CAD patients in whom counts were done. Platelet aggregation was lower in seven patients who were taking propranolol than in the remaining nine who were not taking propranolol. During tachycardia stress, platelet aggregation increased in all patients, but the magnitude of increase was greater in patients not taking propranolol. In four other patients without CAD, platelet aggregation and counts were also studied in the same fashion and were similar in both the aortic and coronary venous blood. These data suggest that in certain CAD patients, platelet consumption or destruction within atherosclerotic vasculature may occur. Propranolol may reduce platelet aggregation at rest and modify excessive aggregation during tachycardia stress in certain CAD patients.
Fibrolipoma of the mitral valve in a child. Clinical and echocardiographic features.
Authors: Barberger-Gateau P , Paquet M , Desaulniers D , Chenard J
Published: June 2012

Echocardiographic examination, performed in a 12-year-old boy who had signs of mitral regulation, showed the presence of an abnormal mass of echoes in the left atrium and mitral orifice. These were initially interpreted as representing an atrial myxoma. Surgical exploration showed that the tumor originated from the posterior leaflet of the mitral valve, and, microscopically, the lesion was diagnosed as a fibrolipoma. The clinical and echocardiographic features of this unique type of cardiac tumor are discussed.
Multicentric origin of the atrial depolarization wave: the pacemaker complex. Relation to dynamics of atrial conduction, P-wave changes and heart rate control.
Authors: Boineau J P , Schuessler R B , Mooney C R , Wylds A C , Miller C B , Hudson R D , Borremans J M , Brockus C W
Published: June 2012

In studies to ascertain the basis of dynamic changes in the P wave, bipolar epicardial potentials were recorded from multiple atrial electrodes in dogs. One hundred to 120 activation times were displayed by a digital computer and used to construct atrial isotemporal activation sequence maps. Changes in heart rate or beat-to-beat cycle length were induced by vagal stimulation or infusion of autonomic mediating drugs. Changes in cycle length were associated with dynamic changes in the atrial activation sequence and surface P-wave. A conspicuous finding was that epicardial atrial depolarization began at three widely separated locations. These three points were consistently present in all animals and were generally located at the 12, 3, and 6 o'clock positions of the superior vena cava-right atrial junction. The dynamic changes in P waves and atrial activation sequence which accompanied the changes in cycle length were due to sudden shifts in the point of earliest activity between the three early sites. Asymmetric atrial depolarization with more rapid conduction along the crista terminalis, superior interatrial band, and pectinate muscles was present in all dogs. Although the anisotropic atrial geometry played an important role in the asymmetric conduction, the widely distributed onset of activity contributed significantly to the uneven spread. The multiple points of origin of the atrial wavefront might be explained by either a trifocal, distributed pacemaker or the epicardial exits of three specialized pathways conducting an impulse emanating from a single focus. These data explain the dynamic variation in P-wave morphology in normal hearts and also imply a relationship between the altered origin of atrial depolarization, atypical P waves, brady- or tachyarrhythmias, and heart rate control.
Recommendations regarding quantitation in M-mode echocardiography: results of a survey of echocardiographic measurements.
Authors: Sahn D J , DeMaria A , Kisslo J , Weyman A
Published: June 2012

Four hundred M-mode echocardiographic surveys were distributed to determine interobserver variability in M-mode echocardiographic measurements. This was done with a view toward examining the need and determining the criteria for standardization of measurement. Each survey consisted of five M-mode echocardiograms with a calibration marker, measured by the survey participants anonymously. The echoes were judged of adequate quality for measurement of structures. Seventy-six of the 400 (19%) were returned, allowing comparison of interobserver variability as well as examination of the measurement criteria which were used. Mean measurements and percent uncertainty were derived for each structure for each criterion of measurement. For example, for the aorta, 33% of examiners measured the aorta as an outer/inner or leading edge dimension, and 20% measured it as an outer/outer dimension. The percent uncertainty for the measurement (1.97 SD divided by the mean) showed a mean of 13.8% for the 25 packets of five echoes measured using the former criteria and 24.2% using the latter criteria. For ventricular chamber and cavity measurements, almost one-half of the examiners used the peak of the QRS and one-half of the examiners used the onset of the QRS for determining end-diastole. Estimates of the percent of measurement uncertainty for the septum, posterior wall and left ventricular cavity dimension in this study were 10--25%. They were much higher (40--70%) for the right ventricular cavity and right ventricular anterior wall. The survey shows significant interobserver and interlaboratory variation in measurement when examining the same echoes and indicates a need for ongoing education, quality control and standardization of measurement criteria. Recommendations for new criteria for measurement of M-mode echocardiograms are offered.
The echocardiographic profile of patients after Mustard's operation.
Authors: Silverman N H , Payot M , Stanger P , Rudolph A M
Published: June 2012

In order to establish an echocardiographic profile of patients with simple transposition after Mustard's operation, we examined the M-mode records of 10 patients who were found to be free of significant abnormalities at follow-up cardiac catheterization. When compared with established normals, right ventricular wall thicknesses and cavity dimensions were increased, while left ventricular wall thicknesses and cavity dimensions fell below the mean. The wall thicknesses, cavity dimensions and ratios of right ventricular preejection period/ejection time and left ventricular preejection period/ejection time were appropriate for the physiologic role of the ventricles rather than their morphologic identity. In each patient, a portion of the intra-atrial baffle was identified behind the pulmonary root. There was variation in baffle position and baffle mobility within the group, as well as in individual echograms. A variety of valve motion abnormalities were noted; these included diastolic flutter of the atrioventricular valves in all 10 patients and systolic anterior motion of the mitral valve in six patients. Paradoxical septal motion was found in nine patients. Although only minimal or no left ventricular outflow gradients were found at catheterization, nine patients had narrowing of the left ventricular outflow tract, 10 had systolic flutter of the pulmonary valve and eight had early partial closure of the pulmonary valve. The finding of a large number of echocardiographic abnormalities in a group of patients with good hemodynamic results suggests that these echocardiographic features are to be expected after Mustard's opration. Furthermore, the reversal of the physiologic role of the ventricles must be considered when interpreting the echocardiographic dimensions and systolic time intervals.
Detection of serum cardiac myosin light chains in acute experimental myocardial infarction: radioimmunoassay of cardiac myosin light chains.
Authors: Khaw B A , Gold H K , Fallon J T , Haber E
Published: June 2012

To develop a more specific plasma test for myocardial infarction, antibodies specific for cardiac myosin light chains (CM-LC) were elicited that showed less than 3% cross-reactivity with skeletal muscle light chains. These antibodies were used to develop a radioimmunoassay for CM-LC that had a sensitivity of 20 ng (+/- 4 SD; P less than 0.001). Normal dog plasma showed no measurable concentrations of CM-LC (n = 6). Plasma samples from 10 dogs with experimental myocardial infarction produced by persistent left anterior descending coronary artery (LAD) occlusion were obtained at 0, 2, 4, 6, 24, 48 and 72 hours. CM-LC were first detectable in all 10 animals 6 hours after occlusion (97.98 +/- 14 ng/ml [mean +/- SEM]; P less than 0.001). Maximal CM-LC levels were usually obtained between 24 and 48 hours. Sham-operated open chest dogs (0--48 hours, n = 3) showed no measurable CM-LC in the plasma samples. Another group of 10 dogs were subjected to 5 hours of LAD occlusion, followed by reperfusion. In four dogs, CM-LC were detectable as early as 1 hour after reperfusion (81.88 +/- 37.75 ng/ml serum). Sera from all 10 dogs showed elevated levels of CM-LC (199.75 +/- 24.0 ng/ml) by 24 hours. Peak CM-LC concentrations were obtained in five dogs at 24 hours (247.0 +/- 35.28 ng/ml) and in another dog at 120 hours (245 ng/ml). Histochemical infarct size was determined to be 0.5--10% of the left ventricular mass at seven days by triphenyltetrazolium chloride staining. The specificity and sensitivity of this radioimmunoassay for detection of CM-LC, unique proteins to the heart, may be valuable in the diagnosis of myocardial infarction.
Relationship of regional myocardial perfusion to segmental wall motion: a physiologic basis for understanding the presence and reversibility of asynergy.
Authors: Massie B M , Botvinick E H , Brundage B H , Greenberg B , Shames D , Gelberg H
Published: June 2012

Experimental work has shown that even small reductions in myocardial perfusion impair contractile performance. We, therefore, studied the relationship between regional perfusion, assessed by thallium-201 scintigraphy and segmental wall motion, quantitated on biplane contrast ventriculograms, in patients with coronary artery disease. We evaluated 270 segments in 54 patients, including 27 without evidence of myocardial infarction. Most normally perfused regions (125 of 140) contracted normally, whereas those with scintigraphic defects at rest were usually asynergic (42 of 46). Surprisingly, 57% (48 of 84) of regions with exercise-induced perfusion defects were also asynergic, including 48% (25 of 52) of those in patients without myocardial infarction. In 22 patients who had intervention ventriculograms, improvement of perfusion abnormalities at rest correlated closely with reversibility of asynergy. Although there was an association between the location and severity of coronary artery stenosis and segmental wall motion, myocardial perfusion during exercise was a significantly better predictor of asynergy. These findings suggest that resting asynergy may occur even in patients without previous infarction, predominantly in regions with jeopardized perfusion. Asynergy in regions with exercise-induced perfusion abnormalities may, therefore, be an indicator of resting ischemia and may be reversible by coronary artery revascularization.
Emergency revascularization for unstable angina.
Authors: Golding L A , Loop F D , Sheldon W C , Taylor P C , Groves L K , Cosgrove D M
Published: June 2012

Emergency revascularization for unstable angina (defined according to criteria of the National Cooperative Study Group) was performed in 100 consecutive patients. The mean interval from onset of pain to operation was one day. Nineteen patients had single-vessel narrowing of greater than 70% of lumen diameter, 32 double-vessel obstruction and 49 triple-vessel disease. Fourteen of these patients had left main trunk obstruction. Four patients died within 30 days, three from complications of myocardial infarction. Seventeen of 96 (18%) early survivors sustained perioperative infarction. After a mean follow-up of 42 months, four late deaths and three late infarctions occurred. Postoperative angiography in 47 patients (mean interval 14 months) showed 86% graft patency. Of 92 survivors, 72 are symptom-free. Three of the four operative deaths occurred within 24 hours postoperatively; in each of these, postmortem examination confirmed a recent myocardial infarction which antedated the operation, despite the absence of new infarction in the peroperative electrocardiogram or elevation of cardiac enzymes. Results from this emergency series suggest that, although myocardium may be salvaged in some instances, in other cases infarction has already occurred and treatment might better be directed toward alleviation of acute ischemia to provide a stable period in which diagnostic studies are performed and acute myocardial infarction may be ruled out.
Ventriculographic features predictive of surgical outcome for left ventricular aneurysm.
Authors: Kapelanski D P , Al-Sadir J , Lamberti J J , Anagnostopoulos C E
Published: June 2012

Although clinical and hemodynamic stability predicted outcome very well when left ventricular aneurysm was electively resected in 25 patients (95% survival), more discriminate criteria were essential for 20 patients undergoing urgent operation for severe myocardial decompensation (50% survival). Three methods of ventriculographic analysis primarily sensitive to the function of the non-aneurysmal left ventricle were evaluated. These methods separated patients undergoing urgent operation into a population with high operative risk (less than 18% survival) and a population with low operative risk (greater than 82% survival). These criteria also separated 15 patients undergoing operation within three months of myocardial infarction into a group with excellent prognosis (greater than 85% survival) and a group with poor prognosis (less than 15% survival). The high operative risk in patients undergoing urgent operation or operation within three months of myocardial infarction, when non-aneurysmal ventricular function is poor, may be too high; it should be undertaken only under unusual circumstances.