bluuebunny/crossref_metadata_2025 huggingface dataset:
Left ventricular wall motion response to intravenous propranolol.
Authors: Shubrooks S J , Zir L M , Dinsmore R E , Harthorne J W
Published: June 2012

The effects of intravenous propranolol on left ventricular wall motion and hemodynamics were studied in 16 patients, 12 with significant coronary artery disease and four with chest pain but no coronary disease. Eight patients received 0.10 mg/kg and eight received 0.15 mg/kg of propranolol intravenously. All underwent atrial pacing at a constant rate. Left ventricular angiograms were performed before and 20 minutes after propranolol. At both doses, propranolol caused no significant change in left ventricular systolic or diastolic pressures, either before or immediately following ventriculography. Cardiac index fell significantly (3.4 plus or minus 0.2 [SEM] to 2.6 plus or minus 0.1 L/min/m-2) with the higher dose only. Of the ten patients with coronary artery disease and adequate ventriculograms, one patient had a normal left ventricle, two had regional hypokinesis, only three had areas of hypokinesis and akinesis, two had dyskinetic and akinetic areas, and two had areas of hypokinesis, akinesis and dyskinesis. No changes in regional contractility occurred with propranolol except for a minimal increase in hypokinesis in one patient at each dosage and equivocal development of a new area of slight hypokinesis in one patient and minimal apex of dyskinesis in another at the higher dosage. Of the four patients without coronary artery disease, two were affected by propranolol, one with initial regional akinesis and dyskinesis had slight worsening with propranolol and one with regional hypokinesis developed a definite new area of hypokinesis. Therefore, propranolol, even in large intravenous doses, resulted in no significant change in left ventricular wall motion in patients with coronary artery disease.
Prolonged left ventricular ejection time in the post-premature beat. A sensitive sign of idiopathic hypertrophic subaortic stenosis.
Authors: White C W , Zimmerman T J
Published: June 2012

Failure of the pulse pressure to increase in the post-premature beat is considered characteristic of idiopathic hypertrophic subaortic stenosis (IHSS). The sensitivity and specificity of this response were compared to the change in left ventricular ejection time (LVET) in 12 patients with IHSS, in ten control patients with valvular aortic stenosis (AS) and in five normal subjects. The post-PVC pulse pressure increased in all normals and in nine of the ten patients with AS. In IHSS this response was inconsistent. A positive Brockenbrough sign was seen in only 33%. On the other hand, LVET increased greater than 20 msec in eleven of twelve patients with IHSS, whereas all normal subjects and all patients with AS showed either decreases in LVET or increases smaller than 20 msec. Prolongation of the LVET during the post-PVC beat greater than 20 msec appears, therefore, to be a more sensitive sign of IHSS than the corresponding change in pulse pressure.
Studies of the absorption and removal of propranolol in hypertensive patients during therapy.
Authors: Chidsey C A , Morselli P , Bianchetti G , Morganti A , Leonetti G , Zanchetti A
Published: June 2012

The variability of plasma propranolol concentrations has been determined in a large group of patients being treated with the drug. Although the average patient achieved a therapeutic plasma level with 160 mg/day, there was marked interpatient variation. This was found to be primarily the result of differences in effective absorption of the drug, which averaged 46% of the oral dose but ranged from 20 to 80%. Propranolol disappeared from plasma with a half-life of 4.7 hours and its removal appeared to follow dose independent kinetics with no evidence of saturation of hepatic metabolism. The derived pharmacokinetic values of volume of distribution and clearance rate have been used to provide guidelines for initiating propranolol therapy intravenously, and the schedule of 8 mg as a loading dose and 0.02 mg/min as a sustaining dose has been suggested.
Echocardiographic evaluation of posterior left ventricular wall motion in muscular dystrophy.
Authors: Kovick R B , Fogelman A M , Abbasi A D , Peter J B , Pearce M L
Published: June 2012

Maximal systolic endocardial velocity (SEVM) and maximal diastolic endocardial velocity (DEVM) were determined echocardiographically in patients with muscular dystrophy (MD). The SEVM of the muscular dystrophy patients was 5.5 +/- 0.9 cm/sec and the DEVM was 13 +/- 3 cm/sec. The SEVM in MD was significantly less than that seen in age-matched normals (P less than 0.05), persons with myotonia congenita (P less than 0.02), deconditioned patients (P less than 0.001), or older normal persons (P less than 0.05). The Sevm of the MD patients was not significantly different from persons with spinal muscular atrophy. The DEVM of the muscular dystrophy patients was significantly less (P less than 0.001-0.05) than any other group. No correlation could be found between age, heart rate, type or severity of dystrophy and SEVM or DEVM values. The echocardiogram was more selective in correctly identigying muscular dystrophy patients than the electrocardiogram. The abnormality in DEVM was present despite lack of symptoms, normal cardiovascular examination, normal chest X-ray and normal electrocardiograms in 18 of 22 patients. We believe that the DEVM correlates with myocardial relaxation.
Echocardiographic diagnosis of pseudoaneurysm of the left ventricle.
Authors: Roelandt J , Brand M , Vletter W B , Nauta J , Hugenholtz P G
Published: June 2012

The echocardiographic features of postinfarction pseudoaneurysm of the left ventricle are described for the first time. Because ultrasound allows the detection of soft-tissue structures in a manner not possible with other diagnostic techniques, the left ventricular wall can be visualized separating the left ventricular cavity from the saccular aneurysm which is delineated by pericardium and/or extracardiac tissue. In addition to these anatomic findings, relevant qualitative hemodynamic data can also be obtained. Echocardiography seems to be a safe and specific method for the diagnosis of left ventricular pseudoaneurysm. It is suggested that echocardiography should be used in the incipeint phase of pseudoaneurysm formation to detect subacute cardiac rupture.
Congenital heart disease in low birth weight infants.
Authors: Levin D L , Stanger P , Kitterman J A , Heymann M A
Published: June 2012

In this study of low birth weight infants (less than 2500 g), we compared the birth weight distribution of patients with patent ductus arteriosus associated with prematurity with that of patients having congenital heart disease other than patent ductus arteriosus. Among 1436 low birth weight infants 37 infants had congenital heart disease other than patent ductus arteriosus and 198 had isolated ductus arteriosus. Infants with congenital heart disease had a mean birth weight of 2018 grams (standard deviation = 370 g) which was significantly greater than that of infants with patent ductus arteriosus. Four of the 37 infants with congenital heart disease other than ductus arteriosus were among 1150 low birth weight infants born in this institution, an incidence of 3.5/1000 live low birth weight infants. Seventy-eight of the 198 infants with patent ductus arteriosus were among 1150 low birth weight infants born in this institution, an incidence of 70/1000 live low birth weight infants. Twenty-one of the 37 infants with congenital heart disease were of appropriate weight for gestational age and 16 were small for gestational age.
Refractory periods of the accessory pathway in the Wolff-Parkinson-White syndrome.
Authors: Tonkin A M , Miller H C , Svenson R H , Wallace A G , Gallagher J J
Published: June 2012

Antegrade (AERPAP) and retrograde (RERPAP) effective refractory periods of the accessory pathway were measured at multiple cycle lengths in 47 patients with the Wolff-Parkinson-White syndrome. In 20 patients the effect of changing cycle length on AERPAP could be determined. In 12 patients Aerpap decreased by 10-45 msec, in six it increased by 10-35 msec, and in two it was unchanged. In 13 of 15 patients in whom the effect of decreasing cycle length on RERPAP could be assessed, RERPAP decreased by 10-60 msec. In eight patients, the shortest AERPAP correlated well (r equals 0.83) with the shortest R-R interval of consecutive pre-excited beats in atrial fibrillation. However, predominantly normal conduction was observed in six of 28 patients with atrial fibrillation, probably because of concealment in the bypass. Therefore, induction of atrial fibrillation during electrophysiological evaluation may privide additional information. The RERPAP at the cycle length of the arrhythmia was shorter than the cycle length of reciprocating tachycardia in all but one of 21 patients. At the same or comparable cycle lengths, AERPAP was usually greater than RERPAP.
Concordance for coronary risk factors among spouses.
Authors: Sackett D L , Anderson G D , Milner R , Feinleib M , Kannel W B
Published: June 2012

Values for several coronary risk factors, including systolic and diastolic blood pressure, serum cholesterol, triglycerides, blood glucose, uric acid, hemoglobin, weight, vitral capacity and cigarette smoking have been found to be similar among spouses in the Framingham Study. However, longitudinal analyses show that this spouse concordance does not increase over a twelve-year observation period, suggesting that it has arisen through the marriage of similar people rather than through the sharing of a common marital environment. Apparent conflicts between cross-sectional and longitudinal findings have been resolved by showing that spouses who were concordant at the begining of the study are more likely to survive to later exams, while discordant spouse pairs tend to be dissolved through the death of one of their members.
Morphologic correlates of technetium-99m stannous pyrophosphate imaging of acute myocardial infarcts in dogs.
Authors: Buja L M , Parkey R W , Dees J H , Stokely E M , Harris R A , Bonte F J , Willerson J T
Published: June 2012

To obtain insight into the mechanism(s) responsible for the direct visualization of acute myocardial infarcts by myocardial scintigraphy with technetium-99m stannous pyrophosphate (99mTc-PYP), scintigraphic and morphologic studies were performed in 22 dogs subjected to occlusion of the proximal left anterior descending coronary artery (LAD). Grossly visible myocardial infarcts occurred in ten of 11 dogs with LAD occlusion for one day, five with LAD occlusion for two days, two with LAD occlusion for seven days and two with LAD occlusion for 13 days. Rare, microscopic foci of necrosis were observed in one dog with LAD occlusion for one day, and no lesions were present in two dogs subjected to temporary LAD occlusion for eight minutes and reflow for 24 hours. In the latter three dogs, 99mTc-PYP myocardial scintigrams were negative. In the 19 dogs with gross infarcts, 99mTc-PYP myocardial scintigrams were strongly positive at one and two days after LAD occlusion, much less positive at seven days and faintly positive at 13 days after occlusion. Positive myocardial scintigrams in most showed "doughnut" patterns, with marked peripheral concentration of radioactivity around central zones of much lower activity. On histologic examination, the one and two-day-old infarcts exhibited subendocardially located central zones and surrounding peripheral zones, both of which showed distinctive histopathological and histochemical features, including the selective occurrence in the peripheral zones of calcified muscle cells with ultrastructurally demonstrable apatite-like crystals in mitochondria. Selective occurrence of high tissue levels of 99mTc-PYP radioactivity also was demonstrated in the peripheral zones of four infarcts. Hearts with older infarcts (seven and 13 days) showed progressive replacement of necrotic myocardium by granulation tissue and progressive reduction in calcium deposits in the areas of damage. The data obtained in this study establish a temporal and topographical relationship between calcium accumulation in acute myocardial infarcts and 99mTc-PYP uptake responsible for scintigraphic detection of the lesions with this radionuclide in dogs subjected to proximal LAD occlusion.
Noninvasive detection of regional myocardial ischemia using rubidium-81 and the scintillation camera: comparison with stress electrocardiography in patients with arteriographically documented coronary stenosis.
Authors: Berman D S , Salel A F , DeNardo G L , Mason D T
Published: June 2012

The sensitivity of rest and stress myocardial perfusion studies using scintillation camera imaging of intravenously administered rubidium-81 (81Rb) in the detection of myocardial ischemia was compared to that of stress electrocardiography by relating results in 40 patients to the degree of stenosis delineated by coronary arteriography. Of 33 patients with greater than 75% stenosis of at least one of the three major coronary vessels (significant stenosis), rest and stress 81Rb imaging detected ventricular ischemia in 29 (88%) whereas simultaneous stress electrocardiography was positive (1 mm or greater horizontal ST-segment depression) in only 19 (58%) of the same patients. Five of the 29 patients who developed stress-induced scintigraphic evidence of ischemia did not develop angina or a positive electrocardiogram with stress. In 31 of the 33 patients with significant coronary stenosis, either the stress scintigram or the stress electrocardiogram was positive. In seven patients with less than 50% narrowing of a major coronary vessel on coronary arteriography, the stress scinitigrams were negative, whereas the stress electrocardiograms were positive in the two of these patients with the syndrome of angina with normal coronary arteriograms. It is concluded that high resolution images of the myocardium can be obtained with 81Rb using the scintillation camera with special shielding, and that rest and stress 81Rb scintigraphy appears to provide greater sensitivity and specificity when compared to stress electrocardiography in the nininvasive identification of significant coronary stenosis.
The echocardiographic assessment of pulmonary artery pressure and pulmonary vascular resistance.
Authors: Hirschfeld S , Meyer R , Schwartz D C , Kofhagen J , Kaplan S
Published: June 2012

Serial assessment of the status of the pulmonary vascular bed requires bed requires cardiac catheterization. We have demonstrated the right ventricular systolic time intervals (RVSTI) may be measured from the pulmonary valve echo. The right ventricular ejection time (RVET) and right pre-ejection period (RPEP) were measured in 45 normal patients. The RVET and RPEP decreased with increasing heart rate but increased with age. The RPEP/RVET, however, was uninfluenced by either age or heart rate. The RPEP/RVET was, therefore, determined from the pulmonary valve echo in 64 patients with congenital heart disease who underwent cardiac catheterization. Increased pulmonary artery diastolic pressure (PADP), pulmonary vascular resistance (PADP), pulmonary vascular resistance (PVR) and mean pulmonary artery pressure (MPAP) resulted inan increased RPEP/RVET. The use of the RPEP/RVET permitted the serial echographic evaluation of the pulmonary vascular bed in selected patients; marked elevation of the ratio indicated the presence of pulmonary hypertension.
Cardiac manifestations of the mucopolysaccharidoses.
Authors: Schieken R M , Kerber R E , Ionasescu V V , Zellweger H
Published: June 2012

The cardiovascular manifestations of the mucopolysaccharidoses (MPS) have not been well characterized. We studied nine children with various forms of MPS, using noninvasive cardiac diagnostic techniques. The echocardiograms of two brothers with Type I H/S MPS showed slow mitral valve early diastolic closure velocities (MVEDC) (18, 29 mm/sec) consistent with mitral stenosis. Each had a soft opening snap, low frequency presystolic murmurs and X-ray evidence of calcific mitral stenosis. Three patients with Type II A MPS had echocardiographic evidence of impaired left ventricular function, suggesting the presence of myocardial damage. One of these had an abnormal electrocardiogram; non had murmurs. No cardiac abnormalities were discovered in two patients with Type III A and IV MPS. One patient with Type VI A MPS had presystolic, holostolic and early diastolic murmurs. A soft opening snap was recorded. The echocardiogram showed a slow MVEDC (18 mm/sec) and a slightly enlarged left atrial dimension (2.2 cm/m2). In summary, noninvasive studies are useful in evaluating patients with MPS. Type I H/S and Type VI A patients may show evidence of valvular deformity, the former associated with mitral valvular calcification and the latter with both aortic and mitral valve involvement. Type II A patients have muscle function abnormalities and Type III A and IV are shown by noninvasive methods to be free of cardiovascular abnormalities.
An improved basis for enzymatic estimation of infarct size.
Authors: Roberts R , Henry P D , Sobel B E
Published: June 2012

Infarct size has been estimated from serial serum creatine phosphokinase (CPK) changes, but the contribution of noncardiac CPK may interfere. Results would also be influenced if CPK disappearance varied with hemodynamic changes. Since MB CPK is a marker more specific to myocardium. infarct size was estimated from serum MB changes in 16 patients. In addition, 21 chronically instrumented conscious dogs subjected to tachycardia, decreased cardiac output or hepatic or renal ischemia were studied to evaluate the dependence of CPK disappearance on hemodynamics. MB CPK in human tissue extracts and serum was quantified with a new, rapid, glass bead-batch adsorption technique, verified with CPK isoenzymes prepared from human myocardium. Among tissues surveyed, only myocardium contained appreciable MB CPK. Infarct size estimated from MB correlated with total serum CPK in patients with uncomplicated myocardial infarction (r=0.97, N=12). In patients with infarction given intramusclar injections, total CPK curves were distorted but MB CPK curves were not apparently affected. Hemodynamic alterations in conscious dogs did not markedly affect the disappearance rate (kd) of intravenously injected, radioactively labeled, canine myocardial CPK, although kd was shown to depend on reticuloendothelial system activity. These findings suggest that estimation of the extent of infarction based on serum MB CPK should be useful despite hemodynamic deterioration associated with infarction or interference of noncardiac CPK.
Electrophysiologic effects of coronary occlusion and reperfusion. Observations of dispersion of refractoriness and ventricular automaticity.
Authors: Levites R , Banka V S , Helfant R H
Published: June 2012

In order to determine the electrophysiological changes that occur during coronary occlusion and following reperfusion, 19 mongrel dogs were studied. Refractory periods were determined by the extrastimulus method in nonischemic and ischemic zones prior to and after variable periods of left anterior descending artery occlusion and reperfusion. After 15-30 minutes of occlusion, refractory periods in the nonischemic zones remained unchanged while in the ischemic zone they shortened by 17%, resulting in a dispersion of refractoriness. Within three minutes of reperfusion, arrhythmias appeared together with a marked directional change of refractory periods to a prolongation by 34% (P less than 0.001) in the ischemic zone and by 3% (P less than 0.02) in the nonischemic zone. Refractory periods returned to baseline values after 60 minutes of reperfusion. After 60-90 minutes of occlusion, refractory periods in the nonischemic zones were unchanged whereas in the ischemic zone they demonstrated a decrease by 28% (P less than 0.01), again resulting in a dispersion of refractoriness. Within five minutes of reperfusion, refractory periods in the ischemic zone prolonged by 44% (P less than 0.001). Similar but smaller directional changes were also seen in nonischemic zones. Concomitant with the observed prolongation in refractory periods frequent ventricular ectopic activity was again documented. In addition, refractory periods did not return to control values after periods of observation up to 120 minutes in this group. In seven dogs, complete heart block was induced to ascertain the rate of idioventricular pacemaker and the effect of ventricular overdrive on the escape interval. Control ventricular rates (53.3 +/- 5.7 beats/min) remained unchanged (52.3 +/- 5.6) following coronary occlusion, but decreased to 48.0 +/- 4.4 (P less than 0.05) during reperfusion. Mean control escape intervals (1.8 +/- 0.2 sec) did not change after occlusion (1.7 +/- 0.2 sec) but prolonged to 2.1 +/- 0.2 sec (P less than 0.05) following reperfusion. In conclusion: 1) sudden prolongation in refractory periods following reperfusion leads to an overshoot resulting in a dispersion of refractoriness temporally related to the onset of ventricular arrhythmias and 2) re-entry, and not enhanced automaticity, appears to be the mechanism for postperfusion arrhythmias.
Effect of digitalis in patients with paroxysmal atrioventricular nodal tachycardia.
Authors: Wellens H J , Düren D R , Liem D L , Lie K I
Published: June 2012

Atrioventricular (A-V) conduction, ventriculo-atrial conduction and mechanism of tachycardia were studied by programmed electrical stimulation before and after the administration of ouabain in 15 patients suffering from paroxysmal supraventricular re-entrant tachycardia. In 13 patients the tachycardia circuit was confined to the A-V node. In two patients the stimulation study showed that an accessory pathway was used in a ventriculo-atrial direction during tachycardia. Ouabain lengthened the effective and functional refractory period of the A-V node and A-V nodal transmission time in all patients in whom this could be studied. Only six patients showed lengthening in ventriculo-atrial conduction time or refractory period of the ventriculo-atrial conduction system. In seven patients no tachycardia could be initiated after ouabain. The width of the zone of atrial premature beats able to initiate tachycardia (the tachycardia zone) narrowed in five patients, showed no change in two patients, and increased in one patient. In these eight patients the tachycardia zone shifted to longer premature beat intervals. Ouabain resulted in slowing of cardiac rate during tachycardia. Both patients who used an accessory pathway during tachycardia showed no change in width of their tachycardia zone following ouabain administration. Seven patients were restudied two weeks after chronic oral administration of digoxin. The results were similar to those obtained following ouabain administration. This indicates that in patients suffering from paroxysmal A-V nodal tachycardia the effect of chronic oral digoxin administration can be predicted from the study of the effect of ouabain during programmed stimulation of the heart.
Comparison of ejection phase indices of left ventricular performance in infants and children.
Authors: Fisher E A , DuBrow I W , Hastreiter A R
Published: June 2012

Ejection phase indices of left ventricular myocardial performance, mean velocity of circumferential fiber shortening (mVcf), mean systolic ejection rate (mSER), and ejection fraction (EF) were determined in 248 pediatric patients, utilizing left ventricular projections of cineangiograms. Heart rate significantly affected mVcf and mSER values in the normal group (r=0.74, 0.79, respectively). A method for heart rate compensation was presented, utilizing a ratio of actual value to expected normal value (A/E) for that heart rate. All indices were significantly lower in the myocardial disease group (12 patients) than in the normal (NI) group (55 patients), but only mVcf (A/E) gave complete separation. There was complete or nearly complete overlap of right ventricular volume and pressure load and left ventricular (LV) pressure load groups (20, 38, and 28 patients each) with NI. For LV volume load (95 patients) mVcf, and mVcf (A/E) mean values were low (P less than 0.025, less than 0.001, resp.). Patients with patent ductus arteriosus had high mVcf and mSER values (P less than 0.05, less than 0.025). MVcf (A/E) was superior to the other indices in identifying patients with depressed myocardial performance.
Acidification of plasma by the red cell due to radiographic contrast materials.
Authors: Lichtman M A , Murphy M S , Whitbeck A A , Pogal M , Lipchik E O
Published: June 2012

The effect of water-soluble radiographic contrast material on pH when added to blood in clinical dosages in vitro or when used in vivo for diagnostic purposes was examined. Contrast material caused a reduction of blood pH. The mechanism of this occurence was found to be the balancing of the negative charge of intracellular organic anions by the extracellular anionic contrast material molecules. The normal negative potential of about 10 mV across the red cell membrane was reduced, nullified, or reversed depending on the concentration of contrast material added to blood. As the inside of the cell became more positive with respect to the outside, protons were, in effect, repelled into plasma, although the apparent exodus of protons occurs by the generation and outward diffusion of carbon dioxide. Since the acidemia is dependent on rehydration of carbon dioxide in plasma, a reaction measured in seconds, the site of injection and transit time of dye will contribute to the pH of the plasma during passage through a regional capillary bed. We speculate that an alteration in membrane potential and/or the acute acidemia may contribute to the adverse effects of contrast material, particularly on tissues dependent on membrane electrical rhythmicity such as the myocardium.
Aberrant course of the left anterior descending coronary artery assoicated with anomalous left circumflex origin from the pulmonary artery.
Authors: Chaitman B R , Bourassa M G , Lespérance J , Dominguez J L , Saltiel J
Published: June 2012

We have presented a two year nonoperative follow-up of an asymptomatic 14-year-old girl with an unusual anomaly of the coronary arteries. Systolic and diastolic murmurs heard preoperatively did not change following severance of a patent ductus arteriosus. Postoperative selective coronary arteriography revealed (1) anomalous orgin of the left anterior descending artery from the right aortic sinus of Valsalva crossing between the aorta and pulmonary artery, (2) aberrant circumflex artery orgin from the pulmonary artery and (3) collaterals from the left anterior descending and right coronary arteries to the circumflex artery. This combination of coronary anomalies has never been described previously.
Initial forces of ventricular depolarization in the Wolff-Parkinson-White Syndrome. Analysis based upon localization of the accessory pathway by epicardial mapping.
Authors: Tonkin A M , Wagner G S , Gallagher J J , Cope G D , Kasell J , Wallace A G
Published: June 2012

The epicardial activation sequence of 34 patients with the Wolff-Parkinson-White syndrome was determined. Epicardial pre-excitation occurred at a spectrum of sites over either the free wall of the left or right ventricle or in a paraseptal region, always adjacent to the atrioventricular rings. The site of pre-excitation was related to the spatial position of the 10 msec vector of the vectorcardiogram (VCG) in 15 patients and the 20 msec vector of the electrocardiogram (ECG) in 29 patients with a single accessory pathway. All patients whose 20 msec vector (ECG) was directed to the right had accessory pathways which caused epicardial breakthrough over the free wall of the left ventricle. When the 20 msec vector (ECG) was to the left and inferior, epicardial pre-excitation was over either the right ventricular free wall or in the region of the pulmonary outflow tract. Superior location of the initial forces, especially the 10 msec vector (VCG), strongly suggested the presence of a septal bypass tract. The polarity of the delta wave and maximum QRS forces in precordial lead V1 were discordant in a significant number of patients, pointing to probable shortcomings of a classification based upon the latter.
Prodromata of myocardial infarction and sudden death.
Authors: Alonzo A A , Simon A B , Feinleib M
Published: June 2012

A sample of 160 hospitalized, acute myocardial infarction patients and 138 individuals who died prior to hospitalization from acute coronary heart disease were studied to determine the incidence and duration of prodromal symptoms and action taken to cope with the symptoms. Seventy percent of the in-hospital subsample (IHS) and 64% of the out-hospital subsample (OHS) reported prodromata. The OHS reported a significantly longer median duration of symptoms than the IHS (29 versus 10.5 days). Sixty-seven percent of the IHS reported new or accelerated anginal symptoms as the most frequently occurring symptom, in contrast to 35% for the OHS. Twenty-seven percent of the IHS and 36% of the OHS consulted a physician about symptoms. Individuals in both subgroups, especially chronically diseased patients, considered their symptoms manageable. Likewise, when contacted, their physicians may have viewed these symptoms as manageable. Patients with a high risk of myocardial infarction and sudden death were significantly more likely to have consulted physicians during the prodromal phase than low-risk patients. A clearly delineated prodromal syndrome is needed so that both lay and medical communities can effectively respond to and intervene during the prodromal phase of acute myocardial infarction and sudden cardiac death.
Amelioration of the effects of ischemic cardiac arrest by the intracoronary administration of cardioplegic solutions.
Authors: Todd G J , Tyers G F
Published: June 2012

Interruption of coronary flow during cardiac surgical procedures provides a bloodless flaccid heart and allows precise and rapid correction of complex cardiac defects. However, myocardial damage occurs in direct proportion to the duration of the ischemia. As the induction of cardioplegia simulataneous with the initiation of cardiac ischemia helps to preserve cardiac energy reserves and thus myocardial integrity, the identification of a consistently reliable cardioplegic technique is desirable. Isolated perfused working rat hearts were made ischemic for one hour by aortic cross-clamping and were compared with hearts rendered cardioplegic at the onset of ischemia by the intracoronary administration of 5 ml of a hypothermic solution: 1) Krebs-Henseleit buffer, 2) Ringer's lactate, 3) tetrodotoxin, 4) potassium chloride, or 5) potassium citrate. Cardiac output, heart rate, aortic pressure and coronary flow were determined pre and post-ischemia. When compared to time-matched controls and hearts arrested with potassium or tetrodotoxin, the ischemia and ischemia-Ringer's lactate groups showed significant post cross-clamp depression of all measured parameters. Intracoronary Ringer's lactate, although often used as an adjunct to ischemic arrest, was not of significant value. In contrast, hearts arrested with tetrodotoxin, potassium chloride or potassium citrate showed no significant post-ischemic functional or histologic deficit. Perfusion with hypothermic Krebs-Henseleit buffer protected the myocardium better than did Ringer's lactate but less well than the tetrodotoxin or isotonic high potassium solutions. The induction of hypothermic metabolic arrest of the heart by briefly perfusing the coronary arteries via the aortic root with isotonic buffered solutions results in markedly improved myocardial tolerance to one hour of ischemia and avoids the problems of low cardiac output and ventricular irritability previously reported with hypertonic potassium citrate arrest.
Normal myocardial contractile state in the presence of quinidine.
Authors: Markiewicz W , Winkle R , Binetti G , Kernoff R , Harrison D C
Published: June 2012

Since quinidine is one of the few agents available to treat and prevent ventricular arrhythmias in ambulatory patients, its hemodynamic effects have been reevaluated. When given in therapeutic doses to anesthetized mongrel dogs, quinidine significantly reduced heart rate, aortic pressure and flow, but it did not significantly change the first derivative of the left ventricular pressure curve (left ventricular dp/dt) in nine dogs. A subsequent group of dogs was studied after vagotomy and practolol administration to block cardiac reflexes. This group showed significant reductions in heart rate, aortic pressure and left ventricular dp/dt, with the latter returning to predrug control values when preload, afterload and heart rate were maintained constant. These studies suggest that quinidine does not directly affect myocardial contractility when given in therapeutic doses. Furthermore, the reduction in heart rate in these animals provides support for a direct depressant effect of quinidine on the sinus node. The adverse effects of quinidine on cardiac function previously reported may be due to the use of toxic doses or are secondary to quinidine peripheral circulatory effects, rather than due to a direct reduction in cardiac contractile state.
Ventricular paired pacing to control rapid ventricular heart rate following open heart surgery. Observations on ectopic automaticity. Report of a case in a four-month-old patient.
Authors: Waldo A L , Krongrad E , Kupersmith J , Levine O R , Bowman F O , Hoffman B F
Published: June 2012

An unusual case is presented in which an atrioventricular (A-V) junctional tachycardia at a rate of 285 beats/min developed in the immediate postoperative period following surgical repair (a Mustard procedure) of transposition of the great vessels in a four-month-old infant. With that heart rate the systolic blood pressure bacame 35-40 mm Hg and urinary output ceased. Ventricular paired pacing was employed successfully to halve the mechanically effective ventricular rate. This resulted in a clinically effective blood pressure and return of normal urinary output. The clinical course of the A-V junctional tachycardia, plus its response to several interventions, suggested that the mechanism of the A-V junctional tachycardia was automatic rather than re-entrant. The study demonstrates that ventricular paired pacing for the control of cardiac arrhythmias is a useful clinical technique in selected cases.
Intraoperative recording of the His bundle electrogram in man. An assessment of its precision.
Authors: Dick M , Krongrad E , Antar R E , Ross S , Bowman F O , Malm J R , Hoffman B F
Published: June 2012

To estimate the effect of distance between the electrode and the signal source on the amplitude of the His bundle electrogram (HBE) recorded during open heart surgery, a specially designed probe, containing six pairs of closely spaced (1 mm) electrodes was placed on the endocardial surface of the right atrium such that each electrode pair was parallel to the course of the His bundle. The amplitude of the HBE recorded through electrodes closest to the His bundle ranged from 0.76 to 2.44 mV, at 1mm from 0.38 to 1.13 mV, at 2mm from 0.27 to 0.86 mV, and at 3 mm from 0.2 to 0.44 mV. Maximal amplitude of HBE decreased by 57% at 1mm, 73% at 2 mm, and 82% at 3mm. The percent decrease was initially rapid, then declined more slowly at distances greater than 1 mm, resembling in form data obtained previously in animal studies by different techniques. Since the maximum HBE was greater than 1.0 mV in nine of 11 patients, and equal to or greater than 1.0 mV in only two of 11 patients at 1 mm, and less than 1.0 mV in all patients 2.0 mm from the maximal HBE, the anatomic location of the His bundle can be estimated from HBE amplitude. Intracardiac electrograms, recorded through closely spaced bipolar electrodes during open heart surgery, afford clinically useful precision in locating the specialized conduction tissue of the heart.
Alterations in ventricular contraction pattern in the Wolff-Parkinson-White syndrome. Detection by echocardiography.
Authors: DeMaria A N , Vera Z , Neumann A , Mason D T
Published: June 2012

The effects of abnormal ventricular activation upon the contractile pattern of the ventricles in patients with the Wolff-Parkinson-White syndrome (WPW) remain uncertain. Therefore we compared the motion of the anterior right ventricular wall (RV), the interventricular septum (IVS), and left ventricular posterior wall (LVPW) on echogram in nine patients with WPW and one patient with a coronary sinus pacemaker (CSP) to 20 normal subjects. Normal subjects manifested posterior RV motion which began and reached maximal excursion at 175 and 366 msec (group mean), respectively, after the onset of the QRS complex; posterior movement of the IVS which started and peaked at 90 and 30 msec, respectively; and anterior contraction of the LVPW which began and peaked at 159 and 406 msec, respectively. Five of seven patients with Type A WPW demonstrated a localized area of premature contraction of the LVPW occuring during the initial 100 msec interval following the onset of the QRS complex which was accompanied by paradoxic anterior motion of the IVS. Thereby in Type A patients initial and maximal posterior motion of the IVS occurred later, 230 (P less than 0.001) and 400 (P less than 0.05) msec, and anterior motion of the LVPW occurred earlier, 75 (P less than 0.001) and 367 (P less than 0.05) msec as compared to normal. The amplitude and duration of early contraction could be related to the prominence of the delta wave during atrial pacing. Similar premature contraction was also observed in the patient with CSP during paced beats. One Type B WPW patient exhibited abnormal IVS motion while the additional patient manifested premature LVPW contraction similat to that seen in Type A patients. The contractile pattern of the right ventricular anterior wall was recorded in five of seven Type A Wolff-Parkinson-White patients and manifested prolongation of the interval from the onset of the QRS complex to the initial posterior movement (group mean 234 msec, P less than 0.05) as compared to normal. Thus echocardiography can be used to confirm the diagnosis and to improve understanding of the pathophysiology of the Wolff-Parkinson-White syndrome.
Echocardiographic determination of left atrial volumes in children with congenital heart disease.
Authors: Yabek S M , Isabel-Jones J , Bhatt D R , Nakazawa M , Marks R A , Jarmakani J M
Published: June 2012

The feasibility of determining left atrial volumes (LAV) from LA echo dimensions was assessed in 36 children (group I) with normal cineangiographically determined LAV and 16 children (group II) with LAV overload. Conventional LA echo dimensions, obtained within 24 hours of cardiac catheterization, were compared to the angiographic LA anterior-posterior minor axes (LAmA) and LAV. There was excellent correlation betweeh the LA echo dimensions and the LAmA. In all patients, the LA echo less than LAmA, the differences being more pronounced in group II. Good correlations were found between the LAV and the LA echo, and were expressed by the equations LAV = 7.5 LA echo1.8 (r = .85) and LAV = 8.1 LA echo2.1 (r = .86) for groups I and II, respectively. Changes in LA configuration with volume overload were shown to cause a disproportionate increase in LAmA compared to the other LA dimensions and the LA echo dimension, thus necessitating the separate regression equations. Echo LA to aortic ratios were 0.86 +/- 0.11 and 1.21 +/- 0.23 (mean +/- SD) for groups I and II, respectively. This method of estimating LAV can be useful in the management of left-to-right intracardiac shunts and mitral regurgitation in infants and children.
Acute effects of increase in pulmonary vascular distending pressures on pulmonary blood volume and pulmonary extravascular fluid volume in man.
Authors: Austin S M , Schreiner B F , Shah P M , Yu P N
Published: June 2012

The acute hemodynamic effects of supine leg exercise or atrial pacing were studied in 114 patients undergoing right and either transseptal (87 cases) or retrograde (27 cases) left heart catheterization. Seventy-one patients - 15 with coronary artery disease, 22 with aortic valve disease, and 34 with mitral valve disease - performed exercise on a bicylce ergometer. Forty-three patients, of whom 22 had coronary artery disease, nine aortic valve disease and 12 mitral valve disease, were studied during rapid atrial pacing. Cardiac index (CI), pulmonary artery mean (PAm), and left atrial mean (LAm) pressure, pulmonary blood volume (PBV) and pulmonary extravascular volume (PEV) were measured during the control state and during acute intervention. Both exercise and pacing resulted in significant elevations in PAm (range 37-65%) and LAm (range 36-43%) mean pressures in all patients. Cardiac index rose between 34 and 58% in the exercise groups, but did not change in those who were paced. During intervention both PBV and PEV increased significantly in all but the nine patients with aortic valve disease who were paced. Although volume increased occurred, they did not achieve the 5% significanc- level. For all patients the mean increment in PBV ranged between 37 and 123 ml/m2 over control, while PEV rose between 15 and 35 ml/m2. In each group the increases in PEV and PBV were proporationate, so that the ratio of PEV/PBV DID NOT CHANGE SIGNIFICANTLY BETWEEN THE CONTROL AND INTERVENTION STATES. Thus PEV and PBV increases occurred with elevations in pulmonary vascular pressures whether or not blood flow increased. Our data in patients with normal pulmonary vascular beds (i.e., coronary artery disease and aortic valve disease) strongly support the hypothesis that recruitment of vascular channels accounts for the acute changes in PEV and PBV and that the changes in PEV over a brief period of time do not necessarily reflect a "true" increase in extravascular lung water. Although pressures are higher in the lungs of patients with mitral valve disease, the data also suggest that recruitment is likely to be the mechanism for the observed proportionate increase in pulmonary extravascular volume and pulmonary blood volume.
De Subitaneis mortibus. XVI. Intractable tachycardia in infancy.
Authors: Brechenmacher C , Coumel P , James T N
Published: June 2012

Intractable tachycardia in a boy proved fatal at the age of one year. A cousin still living has the same problem. Special electrocardiographic studies in the boy demonstrated a consistent abnormality which included complete atrioventricular dissociation with a normal atrial rate but a ventricular rate usually about 240 beats/minute; a His bundle comples preceded each QRS and all QRS complexes were narrow and uniform in configuration without a delta wave. At postmortem examination there were changes due to congestive failure and the heart was enlarged but otherwise normal except for the His bundle. In its midportion the His bundle was split into several thin and irregular longitudinally oriented strands, within which there were many areas of focal degeneration. There was no myocarditis and no focal degeneration elsewhere in the heart. Although the etiology of this process is uncertain, some possibilities are discussed.
Precordial ST-segment mapping. 2. Effects of oxygen inhalation on ischemic injury in patients with acute myocardial infarction.
Authors: Madias J E , Madias N E , Hood W B
Published: June 2012

Precordial ST-segment mapping was serially applied in the Coronary Care Unit for the study of the effect of oxygen inhalation on the ischemic injury in 17 patients with acute anterior transmural myocardial infarction. A 49-lead ECG system was used. The sum of all ST elevations (sigmaST) recorded was taken as an index of magnitude of ischemic injury and the number of recording sites showing ST elevation (NST) was taken as an index of extent of ischemic damage. Stability of the precordial maps was observed over a period of one hour while the patients were on ambient air. Oxygen inhalation for a mean of 66 min resutled in a fourfold increase of PaO2 and a mean of 16% reduction of both sigmaST and NST. When the patients were returned to ambient air breathing, a mean of 13% increase of sigmaST and 19% of NST from the levels recorded during oxygen inhalation were observed. Levels of sigmaST and NST on ambient air following discontinuation of oxygen inhalation were not significantly different from the corresponding values from maps recorded before onset of oxygen breathing. Blood pressure and heart rate remained unchanged throughout the study. Clinical status of the patients was unchanged during the study period save for two patients who showed changes in intensity of their chest pain.
Second degree block during reciprocal atrioventricular nodal tachycardia.
Authors: Wellens H J , Wesdorp J C , Düren D R , Lie K I
Published: June 2012

Of 67 patients with reciprocal atrioventricular (A-V) nodal tachycardia consecutively studied by programmed electrical stimulation of the heart, nine patients showed second degree block toward the ventricle and one patient toward the atrium during tachycardia. In four patients the occurrence of block was critically related to the prematurity of the test stimulus initiating the tachycardia. In three patients block developed following increase in rate of tachycardia. In two patients block could be elicited by introducing premature ventricular stimuli during tachycardia. Our observations indicate that different mechanisms may be responsible for second degree block during reciprocal supraventricular tachycardia. The finding of second degree block during reciprocal supraventricular tachycardia excludes a tachycardia with A-V conduction over the A-V node - His pathway and V-A conduction over an accessory A-V pathway.
Dissociation and delayed conduction in the canine right bundle branch.
Authors: Walston A , Boineau J P , Alexander J A , Sealy W C
Published: June 2012

Bipolar electrograms were recorded from five to six sites on the septal right bundle branch (RBB) using a multielectrode patch in ten mongrel dogs. Antegrade activation was recorded along the right bundle during sinus rhythm and during right atrial pacing at varying heart rates. Retrograde activation was produced by pacing from right ventricular epicardium. Right bundle conduction velocities varied from 1.4 to 3.3 m/sec (mean 2.0 m/sec) for antegrade conduction and from 1.8 to 2.7 m/sec (mean 2.1 m/sec) for retrograde activation. Varying degrees of conduction delay were elicited by premature stimulation and mechanical pressure to the right bundle. The conduction delays occurred over small segments of the right bundle branch with regeneration of normal propagation velocity distal to the region of block. The conduction delays were associated with fragmentation of the RBB electograms with initiation of delayed activation waves which traveled variable distances antegrade and retrograde. These data show that stress-induced longitudinal dissociation may produce delayed activation waves within the right bundle branch which may simulate re-entrant arrhythmias.
The incidence of bacteremia in pediatric patients following tooth extraction.
Authors: Peterson L J , Peacock R
Published: June 2012

Procedures which produce bacteremias may lead to bacterial endocarditis in the susceptible patient. Recent work has suggested that bacteremia does not occur in children following extraction of teeth as it does in adults. One hundred and seven children were divided into four groups. Group I, which consisted of children who had nondiseased primary teeth extracted, had 35% positive blood cultures. Group II consisted of children who had diseased primary and permanent teeth removed. The incidence of positive blood cultures was 53%. Group III, which consisted of patients who had extractions of nondiseased permanent teeth, had a 61% incidence of positive blood cultures. Group IV served as a negative control. Bacteremias do occur in children following the extraction of normal and diseased primary and permanent teeth. Therefore, the susceptible pediatric patient who is to undergo a dental extraction procedure must be given prophylactic antibiotics.