bluuebunny/crossref_metadata_2025 huggingface dataset:
Cardiovascular responses to dynamic and static effort soon after myocardial infarction. Application to occupational work assessment.
Authors: DeBusk R F , Valdez R , Houston N , Haskell W
Published: June 2012

Static and dynamic work involving the arms and the legs was performed by 40 men seven weeks after myocardial infarction. Leg ergometry produced a significantly higher peak work load, systolic blood pressure (BPs), heart rate (HR), and HR X BPs X 10(-2) product (DP) than did arm ergometry: 842 +/- 178 vs 546 +/- 135 kg-m/min, 176 +/- 24 vs 154 +/- 19 mm Hg and 256 +/- 54 vs 219 +/- 48 (SD). Peak heart rates were 145 and 142. Endpoints were primarily muscular and generalized fatigue and dyspnea. Ischemic abnormalities and ventricular ectopy were more frequent with leg ergometry. Sustained forearm lifting elicited higher HR, PBs and DP responses than sustained handgrip contraction: 95 +/- 16 vs 91 +/- 16 beats/min, 162 +/- 18 vs 152 +/- 17 mm Hg and 154 +/- 33 vs 139 +/- 33 (SD). Ischemic ST segment depression and significant ventricuar arrhythmias were infrequent with static effort. Dynamic leg testing is superior to dynamic or static arm testing in assessing the capacity of patients to perform physical work tasks after myocardial infarction.
Relation between left coronary artery stenosis and regional left ventricular function.
Authors: St John Sutton M G , Frye R L , Smith H C , Chesebro J H , Ritman E L
Published: June 2012

The effect of stenosis of the left main and proximal anterior descending coronary arteries on anterior left ventricular wall dynamics was investigated in 70 patients with ischemic heart disease by the use of roentgen videometric analysis of left ventricular angiograms. In all patients with ischemic heart disease, mean values for peak rate of systolic wall thickening and diastolic wall thinning were significantly smaller than normal (P less than 0.01). In patients without infarction, there was no correlation between peak rate of systolic anterior wall thickening and stenosis of the coronary artery supplying it, but there was a significant reduction in peak rate of diastolic wall thinning (P less than 0.01) in patients with stenosis greater than 90%; this difference was not apparent at any lower degree of stenosis. This population could not be recognized by any other parameter of global or regional ventricular function; thus, diastole is more sensitive to regional left ventricular dysfunction than systole.
Computed tomography for localization and sizing of experimental acute myocardial infarcts.
Authors: Gray W R , Buja L M , Hagler H K , Parkey R W , Willerson J T
Published: June 2012

Computed tomography (CT) has been used to quantitate acute myocardial infarct size in isolated, arrested canine hearts. Acute myocardial infarcts were produced in 20 hearts by either left anterior descending (13 dogs) or circumflex coronary artery ligation (seven dogs). Each animal was given iodinated contrast media intravenously immediately before sacrifice 24--72 hours postinfarction. All infarcts greater than 1 g and one of three infarcts 0.5 g or less were detected by CT imaging. Infarct volume determined by CT correlated with gross infarct weight (r=0.83). CT imaging, however, consistently underestimated infarct volume; underestimation was largest in a group of patchy, predominantly subendocardial infarcts. As adequate equipment and techniques for in vivo studies are developed, CT imaging of the heart may become important in clinical evaluation of myocardial infarction.
Complete common atrioventricular canal in infancy--surgical repair and postoperative hemodynamics.
Authors: Culpepper W , Kolff J , Lin C Y , Vitullo D , Lamberti J , Arcilla R A , Replogle R
Published: June 2012

Fourteen infants with complete common atrioventricular canal (CCAVC) underwent open heart surgery under deep hypothermia and circulatory arrest. There were three operative deaths and two late deaths. Postoperative studies performed in seven of the nine survivors revealed nearly normal hemodynamics. There were no residual shunts, and excellent mitral valve function was observed in six patients. In one patient, residual mitral regurgitation was noted. The pulmonary artery pressures and pulmonary vascular resistances were normal except in one who had severe pulmonary vascular obstructive disease before surgery. The mean left ventricular end-diastolic volume changed from 175 +/- 24% (SEM) before surgery to 106 +/- 7% after surgery (P less than 0.01). The corresponding right ventricular end-diastolic volume changed from 166 +/- 16% to 102 +/- 19% (P less than 0.025). Left ventricular ejection fraction was mildly decreased before and after surgery (0.63 +/- 0.02). Surgical repair of CCAVC is possible during the first year of life, with likely normalization of cardiac size and function. Unsatisfactory results related to pulmonary vascular obstruction may be anticipated if repair is delayed much beyond the first year.
Valve replacement in patients with active infective endocarditis.
Authors: Wilson W R , Danielson G K , Giuliani E R , Washington J A , Jaumin P M , Geraci J E
Published: June 2012

Eleven of 138 patients with infective endocarditis (IE) who underwent cardiac valve replacement for IE during a 12 1/2-year period had active IE. Eight of the 11 (all with aortic IE) had positive blood cultures within 48 hours preoperatively; six of the eight had positive Gram stains and cultures of the excised cardiac tissue. All 11 patients had Class IV cardiac functional disability (New York Heart Association classification) at the time of surgery. Staphylococci (three patients with Staphylococcus aureus and one with S. epidermidis) were the most frequent isolates. Three patients died; two of these three deaths occurred in patients who had a sudden onset preoperatively of severe aortic regurgitation and heart failure. In one patient (S. epidermidis infection) prosthetic valve endocarditis developed. Cardiac valve replacement may be performed successfully in patients with active IE even when blood cultures are positive in the immediate perioperative period. The hemodynamic status of patients with IE should be the determining factor in the timing of cardiac valve replacement, rather than the activity of the infection or the length of preoperative antimicrobial therapy. A radical surgical procedure may be necessary in patients with myocardial or aortic abscesses in whom conventional aortic valve replacement is not possible.
Type A behavior pattern and coronary atherosclerosis.
Authors: Blumenthal J A , Williams R B , Kong Y , Schanberg S M , Thompson L W
Published: June 2012

Previous research has demonstrated an increased rate of clinical coronary heart disease (CHD) events among people who exhibit a "coronary prone" (Type A) behavior pattern. This study was undertaken to determine whether the association between behavior pattern Type A and CHD might be extended beyond clinical CHD events to include also the coronary atherosclerotic process. In addition to usual clinical evaluation, 156 consecutive patients referred for diagnostic coronary angiography were independently assessed on the basis of a structured interview and assigned a rating of Type A, Type B, or Type X (indeterminate). Traditional physiologic factors--age, sex, cholesterol and cigarette smoking--were found to correlate with atherosclerotic disease. Type A patients were found in increasing proportions among groups of patients with coronary occlusions of moderate to severe degree compared with patients with only mild occlusions. This increasing proportion of Type A patients with increasing disease severity remained significant, even when age, sex, blood pressure, serum cholesterol level and cigarette smoking history were all simultaneously covaried. These findings suggest that, independently of traditional risk factors, behavior pattern Type A may contribute to the risk of clinical CHD events via effects on the atherosclerotic process.
The clinical significance of bundle branch block complicating acute myocardial infarction. 1. Clinical characteristics, hospital mortality, and one-year follow-up.
Authors: Hindman M C , Wagner G S , JaRo M , Atkins J M , Scheinman M M , DeSanctis R W , Hutter A H , Yeatman L , Rubenfire M , Pujura C , Rubin M , Morris J J
Published: June 2012

To provide an understanding of the clinical characteristics of patients with acute myocardial infarction (MI) and bundle branch block, experience from five centers was accumulated. Patients in whom bundle branch block first appeared after the onset of cardiogenic shock were excluded. In 432 patients, the most common types of block were left (38%) and right with left anterior fascicular block (34%). In 42% of the patients, bundle branch block was new. Progression to high degree (second or third degree) atrioventricular (AV) block via a Type II pattern occurred in 22% of the patients. Hospital and first year follow-up mortality rates were 28% and 28%, respectively. Only 46% of the patients developed pulmonary edema or shock (Killip Class III or IV), and hospital mortality was related to the amount of heart failure (8%, 7%, 27%, 83% for Killip Classes I-IV, respectively). Patients with progression to second degree or third degree AV block via a Type II pattern had increased hospital mortality compared with patients without this complication (47% vs 23%, P less than 0.001). In the absence of pulmonary edema or shock, patients with Type II second degree or third degree AV block still had a higher mortality rate than patients without advanced AV block (31% vs 2%, P less than 0.005), with nearly all the deaths due to abrupt development of AV block. Thus, in many patients MI with bundle branch block is associated with severe heart failure. However, this was not true for a majority of the patients, in whom therapy aimed at preventing morbidity and mortality due to the bradyarrhythmia of advanced AV block might be beneficial.
A new method for measurement of sinoatrial conduction time.
Authors: Narula O S , Shantha N , Vasquez M , Towne W D , Linhart J W
Published: June 2012

This study describes a new method (NM) for estimation of sinoatrial conduction time (SACT), which utilizes constant atrial pacing (AP) instead of the premature atrial beats (PABs) used in the method reported in 1973 by Strauss et al. The SACTs were obtained by both methods in 20 patients. The SACT by the Strauss method (SM) was calculated as A2A3 minus A1A1. The NM consists of high right AP for a train of eight consecutive beats at rates less than or equal to 10 beats/min faster than the sinus rhythm. The interval between the last paced atrial electrogram (Ap) and the first escape atrial electrogram (A) of sinus origin (Ap-A) was measured along with several post pacing sinus cycles. The SACT by the NM was calculated as follows: SACT = Ap-A minus A1A1. The effect of AP at higher rates was also analyzed. In two patients, the SACT with the SM could not be defined, as all the A2A3 intervals were fully compensatory; with the NM the SACT was 217 and 320 msec. In the remaining 18 patients the SACT was obtainable by both methods. With SM, the SACT ranged 105--452 msec (mean 219 +/- 102 SD) and with the NM it was 85--492 msec (mean 201 +/- 112 SD), and the difference was statistically significant (P = 0.0162). The coefficient of correlation between the two methods was r = 0.97. During AP at faster rates, a rate related increment in Ap-A intervals and also post pacing sinus cycles was noted. This study describes a new and simple method for measurement of SACT in man.
Double irregular ventricular parasystole: rate-dependent entrance block and "supernormal" exit conduction.
Authors: Tenczer J , Littmann L
Published: June 2012

An analysis of electrocardiograms from a patient with spontaneous double irregular ventricular parasystole is presented. Irregularity in one of the two parasystoles was produced by intermittence based on rate-dependent (phase 3) entrance block, and in the other parasystole it was attributed to "supernormal" exist conduction. Critical analysis of electrocardiograms revealed that first degree block, rate-dependent block, and "supernormal" conduction in the exit pathway may account for the alterations in the arrangement and manifestation of the parasystolic beats. An electrocardiographic approach to these properties of the parasystolic structure and demonstration of double ventricular parasystole with irregularity in both parasystoles has not previously been found in the literature.
Isolated drainage of the superior vena cava into the left atrium in a 52-year-old man: a rare congenital malformation in the adult presenting with cyanosis, polycythemia, and an unsuccessful lung scan.
Authors: Ezekowitz M D , Alderson P O , Bulkley B H , Dwyer P N , Watkins L , Lappe D L , Greene H L , Becker L C
Published: June 2012

This report describes a 52-year-old black male with the isolated finding of an anomalous superior vena cava draining into the left atrium. The patient presented with dizziness, mild cyanosis, polycythemia and normal cardiac and pulmonary findings. The first major diagnostic clue in this confusing clinical presentation was an unsuccessful lung perfusion scan in which intravenous tracer consistently bypassed the lungs. This appears to be the first adult presenting with this rare anomaly. This condition should be suspected if cyanosis, clubbing, and a "normal" cardiac examination coexist and if the more common pulmonary and hematological causes of this triad have been excluded.
Role of the renin-angiotensin system in the systemic vasoconstriction of chronic congestive heart failure.
Authors: Curtiss C , Cohn J N , Vrobel T , Franciosa J A
Published: June 2012

In 15 patients with severe chronic left ventricular failure, plasma renin activity (PRA) ranged widely, from 0.2--39 ng/ml/hr. The level of PRA was unrelated to cardiac output (CO) or pulmonary artery wedge pressure (PWP), but was slightly negatively correlated with mean arterial pressure (MAP) (r = -0.45) and systemic vascular resistance (SVR) (r = -0.40). After infusion of the angiotensin converting enzyme inhibitor teprotide (SQ 20,881) PWP fell from 26.3 +/- 1.3 (SEM) to 20.3 +/- 1.4 mm Hg (P less than 0.001), CO rose from 3.94 +/- 0.23 to 4.75 +/- 0.31 l/min (P less than 0.001), MAP fell from 87.5 +/- 3.8 to 77.9 +/- 4.1 mm Hg (P less than 0.001) and SVR from 1619 +/- 148 to 1252 +/- 137 dyne-sec-cm-5 (P less than 0.001). The fall in MAP and in SVR was significantly correlated with control PRA (r = 0.68 and r = 0.58, respectively). When subjects were divided on the basis of control PRA the hemodynamic response to teprotide was greatest in the high renin group. PRA rose after teprotide (8.7 +/- 3.4 to 37.9 +/- 7.7 ng/ml/hr, P less than 0.05) but plasma norepinephrine fell (619.1 +/- 103.6 to 449.7 +/- 75.7, P less than 0.05). The renin-angiotensin system thus appears to have an important role in the elevated SVR in some patients with heart failure. Chronic inhibition of converting enzyme should be explored as a possible therapeutic approach.
Comparison of single-dose and double-dose thallium-201 myocardial perfusion scintigraphy for the detection of coronary artery disease and prior myocardial infarction.
Authors: Blood D K , McCarthy D M , Sciacca R R , Cannon P J
Published: June 2012

Thallium-201 myocardial perfusion scintigraphy was performed after exercise, 4 hours after exercise (redistribution) and after a separate rest injection in 87 patients undergoing coronary arteriography. Significant coronary lesions were present in 62 of the patients. Interpretation of the rest and redistribution scintiscans was the same in 69 patients, 45 of whom had coronary artery disease (CAD). In 16 of the 17 patients with CAD and differing interpretations, defects were present on redistribution scintiscans but not on rest scintiscans; 11 of these patients had evidence of prior transmural myocardial infarction and the other five had an occluded coronary artery supplying the region of the defect. Redistribution scintiscans were more sensitive than rest scintiscans for the detection of prior myocardial infarction (93% vs 54%; P less than 0.01). The increased sensitivity was confined to the detection of prior inferior myocardial infarctions. In 36 of 38 patients with persistent perfusion defects on 4-hour redistribution scintiscans, either a prior infarction or an occluded coronary vessel was present. Exercise scintiscans were compared with rest scintiscans or with redistribution scintiscans for the detection of CAD. The sensitivity was not significantly different with either technique (90% and 89%, respectively), but both scintigraphic techniques were more sensitive than exercise electrocardiography (66%, P less than 0.01). These data demonstrate that redistribution thallium-201 scintiscans may be substituted for conventional rest scintiscans, resulting in reduced cost and radiation exposure to the patient.
Effect of sublingual nitroglycerin on regional flow in patients with and without coronary disease.
Authors: Mehta J , Pepine C J
Published: June 2012

We evaluated the effects of sublingual nitroglycerin on indices of regional coronary flow and coronary resistance (CR) in 12 selected patients with coronary artery disease (CAD) and eight with normal coronary arteries (NCA), using continuous thermodilution. Resting total left ventricular flow, reflected by coronary sinus flow (CSF), and anterior regional flow, reflected by great cardiac vein flow (GCVF), in NCA and CAD patient groups, were similar. However, in a subgroup of six patients, with CAD limited to the anterior descending artery, GCVF was lower and anterior regional CR (CRANT) higher than the NCA subjects. Nitroglycerin reduced the systolic pressure-heart rate product similarly in both patient groups. CSF and GCVF in NCA subjects declined 15% and 17%, respectively, as total CR (CRT) and CRANT increased. In the CAD subgroup, consisting of patients with CAD limited to the anterior descending, GCVF increased 48% as CRANT declined 50%, and CSF was unchanged. In the other CAD subgroup of patients with CAD in the right and/or circumflex arteries, GCVF declined 32% and CRANT increased 46% as CSF was minimally increased. These data imply that sublingual nitroglycerin reduces both CSF and GCVF in NCA patients as oxygen demands decrease. In certain CAD patients, however, nitroglycerin alters regional coronary venous blood flow, suggesting a redistribution of flow from normally perfused to hypoperfused regions.
Assessment of cardiac performance with quantitative radionuclide angiocardiography. Effects of oral propranolol on global and regional left ventricular function in coronary artery disease.
Authors: Marshall R C , Berger H J , Reduto L A , Cohen L S , Gottschalk A , Zaret B L
Published: June 2012

The effect of incremental dosages of oral propranolol (mean peak dose of 165 +/- 13 mg/day) of left ventricular ejection fraction, ejection rate and regional wall motion was studied sequentially in 22 stable, resting patients with coronary artery disease using a geometry-independent first-pass radionuclide angiocardiographic technique. All patients improved clinically, in association with a fall in heart rate and therapeutic serum propranolol levels. No significant changes were noted in ejection fraction, ejection rate or regional wall motion. No patient developed a new regional wall motion disturbance. Thus, oral propranolol administered at clinically effective antianginal dosages in patients with stable coronary artery disease does not appear to have significant deleterious effects on resting left ventricular performance.
ST segment changes post-infarction: predictive value for multivessel coronary disease and left ventricular aneurysm.
Authors: Weiner D A , McCabe C , Klein M D , Ryan T J
Published: June 2012

To ascertain whether exercise testing might predict multivessel coronary disease and left ventricular aneurysm after a myocardial infarction, 154 patients with a single documented myocardial infarction who had both exercise testing and coronary angiography were grouped according to whether they had greater than or equal to 1 mm ST depression, greater than or equal to 1 mm ST elevation, or neither during exercise testing: 83 patients developed ST depression alone (group 1); 22 patients had ST elevation with concomitant ST depression in other leads (group 2); 19 patients had ST elevation alone (group 3); and 30 patients had no ST changes (group 4). Multivessel disease, defined as greater than or equal to 70% luminal narrowing in two or more coronary vessels, was present in 76% (63 of 83) of group 1, 91% (20 of 22) of group 2, 21% (four of 19) of group 3, and 13% (four of 30) of group 4. A left ventricular aneurysm was present in 31% (26 of 83) of group 1, 68% (15 of 22) of group 2, 79% (15 of 19) of group 3, and 40% (12 to 30) of group 1. We conclude that ST changes during exercise testing in patients after a myocardial infarction can reliably predict the extent of coronary disease and the presence of a left ventricular aneurysm; ST depression with or without ST elevation predicts multivessel disease; ST elevation alone or a negative exercise test suggests single vessel involvement; and ST elevation with or without ST depression predicts left ventricular aneurysm.
Stability of blood pressure rank and urinary kallikrein concentration in childhood: an eight-year follow-up.
Authors: Zinner S H , Margolius H S , Rosner B , Kass E H
Published: June 2012

Previous studies in a population of 721 children aged 2--14 years demonstrated the familial aggregation of blood pressure in children, and a significant regression coefficient (b = 0.25) of follow-up on initial blood pressures over a four-year period. Urinary kallikrein concentration (UKal) also aggregated in families, was lower in black than in white children and was inversely related to blood pressure. Further studies in the same cohort have been conducted. These variables were again measured in 484 children in 129 families seven to eight years after the initial blood pressure and three to four years after the original UKal measurements were made. Familial aggregation again was found for blood pressure and urinary kallikrein. Blood pressure tracking was demonstrated by the finding that blood pressure scores at the third survey were related significantly to those at both previous surveys. Kallikrein concentrations in casual urines at Survey 3 were related to those obtained at Survey 2 (r = 0.499), and were again significantly lower in black than in white children (log = 3.84 +/- 0.8 vs 4.37 +/- 0.7; P less than 0.001). These were significant inverse relations between UKal/creatinine concentration and blood pressure in both white and black children. Thus, familial aggregation of blood pressure, blood pressure rank and concentration of kallikrein in casual urine specimes are relatively stable in children over an eight-year period of observation. This study demonstrates in a free living population of normal children, a stable relation between blood pressure and an enzyme which is involved in the production of potent vasodilator peptides and is related to hypertension in adults.
Temporary, catheter-induced block in accessory pathways.
Authors: Novick T L , Pritchett E L , Campbell R W , Rogers G C , Wallace A G , Gallagher J J
Published: June 2012

Catheter-induced conduction delay or block in the accessory atrioventricular pathway of four patients with the preexcitation syndrome was observed. Block in the accessory pathway occurred during routine catheter placement and lasted from 90 seconds--14 hours. All of the pathways were in locations readily accessible to catheter trauma, located in the right anterior septal/paraseptal area in three patients, and in the posterior septum near the orifice of the coronary sinus in the fourth. The location of the acessory pathway was confirmed at surgery by endocardial mapping in three of the four patients. The fourth patient did not undergo survey. These findings suggest the need for caution in performing and interpreting electrode catheter studies which are undertaken to document the presence of accessory pathways.
Electrophysiological demonstration of concealed conduction in the human atrium.
Authors: Sung R J , Myerburg R J , Castellanos A
Published: June 2012

In the course of electrophysiological evaluation of six patients with sick sinus syndrome, two patients with chronic conduction system disease and four patients with paroxysmal supraventricular tachycardia or atrial flutter-fibrillation, the phenomenon of concealed conduction within the atrium (At) was repeatedly observed. One pair of intracardiac electrodes was used to deliver electrical stimulus (St) to the high right At and two additional pairs of electrodes were utilized to record high right and low septal right atrial electrograms. The interelectrode distances were 10 mm apart. In all 12 patients, high right atrial capture could be accomplished at a pacing rate of greater than or equal to 200 beats/min. Concealed intra-atrial conduction was evident when the intra-atrial conduction time of the propagated St during 2:1 St-At block was more than 40 msec longer than that during 1:1 St-At conduction at half the St frequency. This indicated that the nonpropagated St during 2:1 St-At block partially penetrated the At and in turn, delayed conduction of the subsequently propagated St. Futher observations revealed that a gradual increase in the St frequency resulted in a progressive prolongation of the intra-atrial conduction time and a shifting of 2:1 to 3:1 St-At block (alternating Wenckebach periodicity in the At) in five patients. These findings clearly demonstrate the occurrence of concealed conduction in the human At.
Fixed coupling: different mechanisms revealed by exercise-induced changes in cycle length.
Authors: Michelson E L , Morganroth J , Spear J F , Kastor J A , Josephson M E
Published: June 2012

Fixed coupled ventricular premature depolarizations (VPDs) are usually considered reentrant; recent experimental models have demonstrated that parasystolic rhythms may also appear in fixed coupled patterns. To analyze the mechanisms of fixed coupled VPDs, 60 exercise tests were chosen to evaluate the response of VPD coupling intervals to changes in cycle length of the dominant supraventricular rhythm. Selection criteria included the presence of frequent, unifocal VPDs that were fixed coupled (variation less than or equal to 80 msec) at any one cycle length, with the persistence of VPDs at several different cycle lengths. Three patterns of response of coupling intervals to changes in cycle length were noted: 1) 32 patients with a direct linear relation (r greater than or equal to 0.9) of coupling intervals to cycle length; 2) 16 patients with coupling intervals fixed, independent of cycle length; and 3) 12 patients with no consistent relation over a wide range of cycle lengths. Two patients in group 2 and four in group 3 fulfilled criteria for parasystole with interectopic intervals that remained constant at different cycle lengths. These results suggest that VPDs in group 1 are reentrant, while some patients with group 2 or 3 responses have evidence for parasystolic rhythms. We conclude that 1) fixed coupling of VPDs is not diagnostic of reentry, and 2) changes in cycle length induced with exercise may be useful in the analysis of mechanisms of VPDs.
Abolition and modification of reentry within the His-Purkinje system by procainamide in man.
Authors: Reddy C P , Lynch M
Published: June 2012

The effects of intravenous procainamide infusion of 10--14 mg/kg body weight (i.e., 750 mg) of procainamide (PA) on reentry within the His-Purkinje system (HPS) were studied in 13 patients using His bundle electrograms and ventricular extrastimulus method. PA abolished reentry in eight patients (group 1) and decreased the width of reentry zone in the remaining five (group 2). At comparable S1S2 intervals, the S2H2 intervals after PA were longer than control in all patients. In group 1 patients, after PA, reentry did not occur even at S2H2 intervals that were significantly longer than control critical S2H2 intervals. In two of eight patients in group 1, PA abolished reentry by converting unidirectional block into bidirectional block in the antegrade limb (right bundle) of the reentry circuit. In the remaining six patients reentry was abolished because of consistent retrograde block of S2 impulse at some point between the site of stimulation and the His bundle recording site. In group 2, reentry was initiated after PA at approximately the same S1S2 intervals as in control, but required significantly longer S2H2 intervals; in these patients the zone of reentry was shortened due to increase in effective refractory period of the ventricular muscle. PA significantly increased the functional refractory period of HPS and the effective refractory period of ventricular muscle. The results of this study differ from the previously reported effects of lower concentrations of PA which facilitated reentry within the same circuit. We conclude that the effects of PA on reentry are dose-related and can both facilitate and suppress reentry, depending on critical changes in conduction and refractoriness of the HPS.
Differentiation of posterior myocardial infarction from right ventricular hypertrophy and normal anterior loop by echocardiography.
Authors: Kramer N E , Chawla K K , Patel R , Khan M , Mayer T , Towne W D
Published: June 2012

The differentiation of posterobasal myocardial infarction (PMI) from either right ventricular hypertrophy (RVH) or normal subjects displaying an anterior loop (AL) by electrocardiography (ECG) or vectorcardiography (VCG) is difficult. M-mode echocardiography (echo) via the anterior and subxiphoid methods has been helpful in defining cardiac chamber size and wall motion abnormalities. We tested whether this relatively more direct method would better separate these entities compared with the other two techniques. ECG and VCG using established criteria failed to distinguish the three conditions effectively. By echo, distinguishing characteristics were observed in each of the groups. Thus, right ventricular diastolic dimension and wall thickness were significantly increased only in the RVH group, echo dimensions and wall motion were normal in the AL group and the posterior left ventricular systolic thickening response and ejection phase indices were significantly reduced only by the subxiphoid method in the PMI group. To test the specificity of the latter finding, posterior wall motion in three infarction groups (posterior, combined posteroinferior and inferior) were examined and suggested that the target of the subxiphoid beam focuses on a more superior posterobasal left ventricular segment than the anteriorly placed transducer. Echocardiography can differentiate PMI from either RVH or AL more directly than ECG or VCG, and may be of practical clinical importance.
Myocardial infarction size from serial CPK: variability of CPK serum entry ratio with size and model of infarction.
Authors: Cairns J A , Missirlis E , Fallen E L
Published: June 2012

To study the variability of the fraction of CPK released from the infarcted heart which enters the serum (serum entry ratio, or SER) with size and model of infarction, nine dogs underwent homogeneous infarctions (LAD ligation) of varying sizes, and 10 dogs underwent scattered infarctions (left coronary embolization). In homogeneous infarcts there was an inverse linear relationship of SER to infarct size (IS) (SER = -0.8514% LV + 0.345, r = 0.98). No such relationship was found for scattered infarcts. CPK Kd (exponential disappearance constant for CPK) was not significantly different in homogeneous (-0.00178 min-1) vs scattered infarcts (-0.00195 min-1). Although similar IS was produced in each (homogeneous 19.9% LV, scattered 18.4% LV) cumulative CPK serum entry (CPKr) was much lower in homogeneous (4175 mlU/ml) vs scattered infarcts (7,296 mlU/ml). SER was also much lower in homogeneous (17.7%) vs scattered infarcts (29.0%) (P less than 0.025). Cumulative CPK plateau occurred significantly later in homogeneous (15.8 hours) vs scattered infarcts (11.7 hours) (P less than 0.01). Further corrections to the serial CPK equations for IS determination are indicated. The method may not be applicable in some infarct situations, e.g., scattered infarction.
Relationship between plasma concentration and dose of digoxin in patients with and without renal impairment.
Authors: Okada R D , Hager W D , Graves P E , Mayersohn M , Perrier D G , Marcus F I
Published: June 2012

The purpose of this study was to determine if there is a linear relationship between oral doses of digoxin and various measurements of steady-state digoxin plasma concentration and urinary excretion in patients with wide range of renal function. Ten patients (mean age 58 years) with creatinine clearances greater than 50 ml/min/1.73 m2 BSA (mean creatinine clearance 80 ml/min/1.73 m2 BSA) and nine patients mean age 61 years) with creatinine clearances less than 50 ml/min/1.73 m2 BSA (mean creatinine clearance 20 ml/min/1.73 m2 BSA) were given digoxin tablets orally at two or three different dose levels (dose range 0.0313--0.5 mg/day). After a dosing period equal to at least five half-lives, three to four consecutive daily digoxin plasma concentrations were determined. Plasma concentrations and urinary digoxin excretion were measured during one 24-hour dosing interval at each dose level. Digoxin plasma and urine concentrations were determined in triplicate using radioimmunoassay. Individual patient plots provided evidence of linearity for: digoxin 24-hour steady-state plasma concentration vs dose; digoxin 24-hour cumulative urinary excretion versus dose; and area under the digoxin plasma concentration-time curve during a 24-hour dosing interval vs dose. Absolute values for these various parameters indicated substantial interpatient variation probably due to patient differences in both digoxin absorption and digoxin total body clearance. These results indicate that there is a linear relationship between digoxin plasma concentration and dose in patients with normal and decreased renal function. This linearity is support for dose-independent pharmacokinetics of digoxin in man. We conclude from these data that a change in digoxin dose should result in a proportional change in digoxin plasma concentration over the dose range examined.
Cardiac metabolsim: its contributions to alcoholic heart disease and myocardial failure.
Authors: Bing R J
Published: June 2012

Changes in cardiac metabolism in myocardial failure and after alcohol ingestion are discussed. The main effect of alcohol ingestion is loss of cardiac contractility. Since heart muscle does not contain alcohol dehydrogenase, its toxicity is probably the result of a direct toxic effect of ethanol and acetaldehyde on the myocardial cell, possibly involving various membrane systems. Alcohol inhibits mitochondrial respiration and the activity of enzymes in the tricarboxylic acid cycle, and its interferes with both mitochondrial calcium uptake and binding. Ethanol profoundly affects myocardial lipid metabolism. Acetaldehyde diminishes myocardial protein synthesis and inhibits Ca++-activated myofibrillar ATPase. In myocardial failure, a series of possibilities may be responsible for the loss of contractility. Excitation-contraction coupling could be disturbed at the level of the sarcolemma, at the sarcoplasmic reticulum, at the mitochondria, and between calcium and the regulatory proteins. Deficiencies in Ca++ delivery systems of excitation-contraction coupling on the myosin ATPase activity could be responsible for the dimunition in cardiac contractility. Mitochondrial function may also be involved, since mitochondria from failing human hearts are defective with respect to respiratory control and calcium accumulation. Under certain conditions, the relationship of mitochondria to calcium sequestration is very important in influencing contractility. The involvement of contractile and regulatory proteins in myocardial failure cannot be excluded.
Spontaneous course of ST-segment elevation in acute anterior myocardial infarction.
Authors: Essen R , Merx W , Effert S
Published: June 2012

The spontaneous course of ST-segment elevation (sigmaST) in 24 patients with acute anterior myocardial infarction (AMI) was studied by precordial ST-segment mapping, which was recorded at 2-hour intervals during the first 48 hours after admission. Change of sigmaST between two registrations was expressed as mV/hr, and was compared with clinical and hemodynamic parameters, course of MB-CK curve, calculated infarct mass and arrhythmias. After an initial rapid increase, there was a decrease of sigmaST, which reaches a plateau-like curve approximately 12 hours after the onset of chest pain. A second new increase of sigmaST exceeding a value of 0.6 mV/hr correlates well with extension of necrosis, verified by re-elevation of MB-CK. During the first 2 days, extension of necrosis could be detected in 50% of our patients. As new ischemic episodes and extension of necrosis in AMI occur frequently and are promptly indicated by an increase of sigmaST, the physician should, while monitoring therapeutic interventions, concentrate on such a second increase rather than on a decrease of sigmaST (which may occur spontaneously), as has been suggested in most previous reports.
Cardiac effects of acute ethanol ingestion unmasked by autonomic blockade.
Authors: Child J S , Kovick R B , Levisman J A , Pearce M L
Published: June 2012

We assessed the effects of ethanol and autonomic blockade on left ventricular function in nine normal subjects, age 20--35 years, using M-mode echocardiography and systolic time intervals. On day 1, measurements were made of heart rate, mean velocity of circumferential fiber shortening, and left ventricular pre-ejection period and left ventricular ejection time ratio (PEP/LVET), during a control period and after autonomic blockade. Autonomic blockade was produced with intravenous propranolol (0.2 mg/kg body weight) and atropine (0.04 mg/kg body weight). On day two, measurements were again made during a control period, then with ethanol alone, followed by addition of autonomic blockade to ethanol. One hundred eighty milliliters of ethanol were ingested over 60 minutes, resulting in a mean blood ethanol level of 110 mg/dl (range 77--135 mg/dl) at 60 minutes post-ingestion. There were no significant differences between the control data on days 1 and 2. Blood pressure was unchanged throughout the study. study. On day 1, autonomic blockade alone resulted in the expected increase in heart rate (p less than 0.001), with a proportional increase in mean velocity of circumferential fibr shortening (p less than 0.01), and an increase in PEP/LVET (p less than 0.01). On day 2, ethanol alone resulted in no significant changes except for a slight increase in PEP/LVET (p less than 0.02). Ethanol plus autonomic blockade, (day 2), compared with autonomic blockade alone (day 1), revealed a decrease in mean velocity of circumferential fiber shortening (p less than 0.05), and an increase in PEP/LVET (p less than 0.01), with a decrease in intrinsic heart rate (p less than 0.001). We conclude that in normal subjects: 1) autonomic blockade does not directly affect contractility; 2) acute ethanol ingestion alone does not produce important changes in cardiac function; and, 3) ethanol in the autonomic blockaded heart causes a significant decrease in contractility. Thus, we infer that ethanol has a negative inotropic effect which is masked by catecholamines and/or autonomic nervous system discharge.
Prevalence and characteristics of disporportionate ventricular septal thickening in infants with congenital heart disease.
Authors: Maron B J , Edwards J E , Moller J H , Epstein S E
Published: June 2012

Necropsy studies were performed in 125 infants, 2 years old or less, with a variety of congenital heart malformations. Disproportionate ventricular septal thickening (septal-to-left ventricular free wall thickness ratio greater than or equal to 1.3) was present in 31 (25%) of the 125 patients. In the majority of patients, an abnormal septal-to-free wall ratio did not appear to be a manifestation of genetically transmitted hypertrophic cardiomyopathy, since: 1) marked disorganization of septal myocardium (involving greater than or equal to 5% of the tissue section) was present in only five of the 31 patients with disproportionate septal thickening; and 2) echocardiographic studies in first degree relatives of four other patients with disproportionate septal thickening and normal septal architecture did not show asymmetric septal hypertrophy. The relatively high prevalence of septal-to-free wall ratios of 1.3 or greater in this population of infants with congenital heart disease appeared to be due in part to minor differerences in ventricular wall thicknesses (in patients with relatively thin absolute wall thicknesses) which may produce particularly large deviations from unity in septal-to-free wall ratio. Hence, 1) nongenetically transmitted disproportionate septal thickening is relatively common in infants with congenital heart diseases studied at necropsy: and 2) a septal-to-free wall ratio of greater than or equal to 1.3 cannot be used as the sole criterion for identifying associated hypertrophic cardiomyopathy in infants with other congenital heart diseases, particularly if marked absolute septal thickening is absent.
Cross-sectional echocardiographic diagnosis of coronary artery aneurysms in patients with the mucocutaneous lymph node syndrome.
Authors: Yoshikawa J , Yanagihara K , Owaki T , Kato H , Takagi Y , Okumachi F , Fukaya T , Tomita Y , Baba K
Published: June 2012

Real-time cross-sectional echocardiographic studies revealed the presence of coronary artery aneurysms in five patients with mucocutaneous lymph node syndrome. These lesions appeared as circular echo-free spaces with clearly-defined borders in sites corresponding to angiographically proven aneurysms. In 15 normal subjects who were studied only by noninvasive methods, and in 17 who had normal coronary arteriograms (including eight with the mucocutaneous lymph node syndrome), we found no similar echo findings. The aneurysms were in both right and left coronary arteries in three patients, and were confined to the left side in two. The mucocutaneous lymph node syndrome is an increasingly common condition in Japan which may be fatal due to myocardial infarction occurring in a setting of coronary aneurysm with thrombosis. Therefore, the ability to demonstrate coronary aneurysms noninvasively is of prognostic and potentially therapeutic value in this inadequately understood syndrome.
Epicardial activation of the intact human heart without conduction defect.
Authors: Wyndham C R , Meeran M K , Smith T , Saxena A , Engelman R M , Levitsky S , Rosen K M
Published: June 2012

To describe the epicardial ventricular activation sequence in the intact human heart, we obtained epicardial maps from 11 patients with normal QRS undergoing open heart surgery. Epicardial breakthrough (EBT), defined as the emergence of a radially propagating epicardial wavefront, occurred in three to five sites in each patient, and was earliest in the anterior right ventricle, 7--25 msec (mean 17 msec) after the onset of the QRS in all patients. Subsequent EBT occurred in the inferior right ventricle (10 sites in 10 patients), in the anterolateral left ventricle (13 sites in 10 patients), and the inferior left ventricle (eight sites in seven patients). Latest epicardial activation (LEA), defined as the latest site of recordable epicardial activity, occurred in the basal segments in all patients, anteriorly in the right ventricle in five patients, and inferiorly in six patients, four on the right and two on the left. LEA occurred 63--96 msec (mean 77 msec) after the onset of the QRS, and was recorded within 20 msec of the end of the QRS in all patients. Sequence of epicardial activation reflected a fusion process among the wavefronts. This descriptive and quantitative data should provide a suitable basis for comparison of abnormal ventricular activation sequences in patients undergoing surgery for preexcitation or ventricular tachycardia.
Dilatation of the ductus arteriosus by prostaglandin E1 in aortic arch abnormalities.
Authors: Heymann M A , Berman W , Rudolph A M , Whitman V
Published: June 2012

Infants with aortic arch interruption of juxtaductal coarctation of the aorta may depend on patency of the ductus arteriosus to provide adequate lower body perfusion. In many such infants the ductus arteriosus constricts after birth, resulting in severe heart failure, poor systemic perfusion and acidemia. We infused prostaglandin E1 (PGE1) at a rate of 0.05--0.1 microgram/kg/min into seven infants with aortic arch interruption and eight infants with coarctation. In one infant in each group the ductus arteriosus was already closed and did not reopen. In one infant with coarctation an adequate trial was not accomplished, and in another adequate pressure measurements were not obtained. Of the remaining 11, the ductus arteriosus was effectively dilated by PGE1 in 10 infants. This was evidenced by an increase in descending aortic blood pressures and a reduction in the pressure difference between the main pulmonary artery and descending aorta in six infants with aortic arch interruption and between ascending and descending aorta in four infants with coarctation. Lower body perfusion improved and left ventricular failure was improved. The infant who did not respond was 5 months old. There were no complications.
Anatomy of aortic atresia. Cases presenting with a ventricular septal defect.
Authors: Thiene G , Gallucci V , Macartney F J , Del Torso S , Pellegrino P A , Anderson R H
Published: June 2012

The anatomy of 58 specimens of aortic outflow tract atresia was studied. All cases had situs solitus and levocardia, 37 had atrioventricular (AV) concordance, two had common inlet to a right ventricle and 19 had mitral atresia. The great arteries were normally interrelated in all cases. Fifty-one cases had an intact ventricular septum, while seven presented with a ventricular septal defect (VSD). Of the seven with VSD, in two it was associated with a common AV orifice draining exclusively into the right ventricle in the presence of a rudimentary left ventricular chamber. In one case a small VSD accompanied combined mitral and aortic atresia. In the other four cases the left ventricles and mitral valves were fairly normal in size; the VSD was subpulmonary in three cases, due to infundibuloventricular malalignment, and perimembranous in one. These last four cases are of particular interest since they could be amenable to surgical correction. Possible approaches to surgical treatment and morphologic features pertinent to them are described and discussed.
Catecholamines in coronary sinus and peripheral plasma during pacing-induced angina in man.
Authors: Schwartz L , Sole M J , Vaughan-Neil E F , Hussain N M
Published: June 2012

We measured aortic and coronary sinus dopamine (DA), epinephrine (E), and norepinephrine (NE) in eight patients with cardiac ischemia (I) and eight control subjects (C). Samples were taken at rest (73 +/- 3 beats/min in C and 68 +/- 3 beats/min in I) and during coronary sinus pacing to peak rates (144 +/- 4 beats/min in C and 136 +/- 6 beats/min in I). Arterial NE was higher in the ischemic patients at rest (254 +/- 25 pg/ml in C and 324 +/- 21 in I; p less than 0.05). There were no differences in arterial E and DA. Neither pacing nor angina affected peripheral catecholamine concentrations. Resting myocardial NE flux was similar for both groups. With pacing, coronary sinus flow and net myocardial NE release increased significantly in both groups. The maximum relative increase in net myocardial NE release was less in the ischemic patients than in the controls (575 +/- 145% in C and 255 +/- 40% in I; p less than 0.05). Thus, angina induced by pacing does not augment peripheral sympathetic activity. Furthermore, pacing-induced angina appears to be associated with a decrease in cardiac sympathetic tone compared with that found in paced controls.