bluuebunny/crossref_metadata_2025 huggingface dataset:
Assessment of preoperative left ventricular function in patients with mitral regurgitation: value of the end-systolic wall stress-end-systolic volume ratio.
Authors: Carabello B A , Nolan S P , McGuire L B
Published: June 2011

Twenty-one patients with symptomatic, chronic, severe mitral regurgitation (MR) but without other valvular heart disease or coronary disease were evaluated to determine which hemodynamic and angiographic factors might be prognostic of surgical outcome. Sixteen patients were in New York Heart Association functional classes I or II postoperatively and formed group A. One patient remained in class III postoperatively and four patients died perioperatively; they constitute group B. End-diastolic volume index (EDVI) was less for group A than for group B, 119 +/- 25 ml/m2 vs 170 +/- 28 ml/m2 (p less than 0.001). End-systolic volume index (ESVI) was also lower in group A, 39 +/- 19 ml/m2 vs 72 +/- 32 ml/m2 for group B (p less than 0.01). The ratio of end-systolic wall stress to end-systolic volume index (ESWS/ESVI) was examined in normal persons and in groups A and B. This ratio was significantly lower in both groups than in normal persons, indicating relatively greater end-systolic volume at a given wall stress, suggesting left ventricular dysfunction. The ESWS/ESVI ratio in group B, 2.2 +/- 0.2, was significantly less than in group A, 3.3 +/- 0.4 (p less than 0.001). The variables of age, pulmonary capillary wedge pressure, EDVI, ESVI, ejection fraction and the ESWS/ESVI ratio were subjected to stepwise discriminant multivariate analysis to determine if any were independent predictors of outcome. The only independent predictor determined by this method was the ESWS/ESVI ratio (p less than 0.001). We conclude that the ESWS/ESVI ratio may be helpful in evaluating left ventricular function and operative risk in patients with chronic, symptomatic MR.
Verapamil versus placebo in relieving stable angina pectoris.
Authors: Pine M B , Citron P D , Bailly D J , Butman S , Plasencia G O , Landa D W , Wong R K
Published: June 2011

Verapamil and placebo were compared in patients with stable, effort-induced angina. Single-blind dose titration (240, 360 and 480 mg/day) preceded a double-blind crossover. Among the 18 patients who completed graded exercise stress tests with reproducible pretreatment effort-limiting angina, exercise duration increased from 348 +/- 127 seconds (SD) before treatment to 494 +/- 182 seconds after verapamil (p less than 0.001), but did not change after placebo. Compared with placebo, verapamil reduced the weekly number of anginal episodes from 4.54 +/- 5.03 to 2.44 +/- 3.30 (p less than 0.05) and reduced nitroglycerin consumption from 3.46 +/- 5.30 to 1.55 +/- 2.89 tablets per week (p less than 0.05). Of 26 patients who completed the single-blind dose titration, 16 were improved (greater than 1 minute) at a dosage of 240 or 360 mg/day. No patient improved (greater than 1 minute) on 480 mg/day who had not already improved on a lower dose, but side effects requiring reduction in dosage occurred in seven patients receiving 480 mg of verapamil per day. Verapamil is an effective antianginal drug that appears most efficacious at a dose of 360 mg/day, but side effects are common at a dose of 480 mg/day.
Postinfarction angina caused by coronary arterial spasm.
Authors: Koiwaya Y , Torii S , Takeshita A , Nakagaki O , Nakamura M
Published: June 2011

Recurrent ST-segment elevations in leads where new Q waves developed were repeatedly recorded in six patients during a recovery phase of acute myocardial infarction. Such ST-segment elevations were transient, occurred with or without chest pain, and returned to control levels. No enzymatic changes signifying recurrent myocardial necrosis were found after each episode. Selective coronary cineangiography in one patient demonstrated a mild segmental stenosis in the coronary artery perfusing the infarcted area; this artery became completely occluded after administration of i.v. ergonovine. Administration of calcium antagonists effectively reduced the frequency of postinfarction angina and ST-segment elevations. The clinical features suggest that the postinfarction angina in these patients is produced by coronary arterial spasm and that coronary arterial spasm may cause severe life-threatening dysrhythmias.
Factors that affect the reproducibility of measurements of left ventricular function from first-pass radionuclide ventriculograms.
Authors: Dymond D S , Elliott A , Stone D , Hendrix G , Spurrell R
Published: June 2011

To examine which factors affect the reproducibility of ejection fraction (EF), pulmonary transit time (PTT) and segmental wall motion assessed from first-pass radionuclide angiograms (FPRA), 32 patients who had FPRA were randomized for site of injection of isotope (right or left arm) and projection (right or left anterior oblique [RAO or LAO]). The quality of injected bolus was measured from the full width at half maximum (FWHM) of the bolus time-activity curve in the superior vena cava. All patients had two sequential studies on each of two consecutive days, and each study was analyzed independently by two observers. For EF, inter- and intraobserver correlations ranged from 0.94-0.98. EF was higher in the RAO than the LAO projection (mean 47.4% vs 40.3%, p less than 0.001), but neither injection site nor bolus FWHM affected the results. For PTT, interobserver correlations ranged from 0.75-0.93 and intraobserver correlations from 0.61-0.85. Variability in PTT was large, and inter- and intraobserver variabilities were directly related to bolus FWHM (mean 0.60 +/- 0.21 second for interobserver differences in PTT of less than 2.0 seconds, mean 1.55 +/- 0.86 seconds for interobserver differences in PTT of greater than 2 seconds [p less than 0.005]). Differences in FWHM between sequential studies were 0.28 +/- 0.29 second when intraobserver differences in PTT were less than 2 seconds and 1.04 +/- 0.67 seconds when differences in PTT were greater than 2.0 seconds (p less than 0.005). Variations in PTT were not related to differences in projection or injection site. Wall motion was highly reproducible for both projections. In the RAO projection, one of 116 anterior segments (0.9%), one of 116 apical segments (0.9%), and four of 116 inferior segments (3%) were judged normal from one observer's images and abnormal from another. In the LAO view, discrepancies occurred in one of 126 septal segments (0.8%), two of 126 apical segments (1.6%) and four of 126 posterolateral segments (3%). This study shows that EF and wall motion are highly reproducible in any projection, but the choice of projection significantly affects the values for EF from FPRA. PTT measurements are less reliable, highly bolus dependent, and their use in clinical practice depends on quality control of the bolus of injected radionuclide.
Immediate diagnosis of acute myocardial infarction by two-dimensional echocardiography.
Authors: Horowitz R S , Morganroth J , Parrotto C , Chen C C , Soffer J , Pauletto F J
Published: June 2011

To define the role of portable two-dimensional echocardiography (2-D echo) in the immediate diagnosis of acute chest pain syndrome, 80 consecutive patients were studied. Adequate 2-D echo studies were obtained in 65 (81%). Thirty-three patients had clinical evidence of transmural or nontransmural acute myocardial infarction (AMI), 18 of whom had nondiagnostic initial ECGs. Thirty-two did not have a clinical AMI. Thirty-one of the 33 (94%) patients with clinical AMI had regional wall motion abnormalities on the initial 2-D echo; the other two had uncomplicated nontransmural AMIs, diagnosed only by ECG in one and by ECG and moderate elevation of CK-MB isoenzyme in the other. Twenty-seven of the 32 patients without clinical AMI had normal regional wall motion on the initial 2-D echo and none had a complication (severe arrhythmia, recurrent pain, heart failure or death) during the hospital course. Conversely, 10 of the 36 patients with initial 2-D echo regional wall motion abnormalities had a complication (p less than 0.05). Thus, in patients with acute chest pain syndrome, an initial 2-D echo that shows no regional wall motion abnormality suggests that such patients will not develop an AMI or clinical complication during the hospital course. An initial 2-D echo with regional wall motion abnormality identifies a high-risk group of patients who are likely to have AMI and important cardiac complications and may, therefore, benefit from admission to an intensive care unit.
Procainamide and retrograde atrioventricular nodal conduction in man.
Authors: Shenasa M , Gilbert C J , Schmidt D H , Akhtar M
Published: June 2011

Recent studies that show a depressant effect of procainamide (PA) on retrograde conduction in patients with atrioventricular (AV) nodal reentrant tachycardia (RT) have suggested possible incorporation of AV nodal bypass tracts. Electrophysiologic effects of i.v. PA, 10 mg/kg, on retrograde AV nodal conduction were examined in 13 patients without RT, demonstrable AV nodal refractory period curves, or accessory pathways. Ventriculoatrial (VA) conduction was recorded before and after PA using intracardiac electrograms, incremental ventricular pacing and extrastimulation. With incremental pacing during the control, VA block occurred at a mean cycle length (CL) of 364.6 +/- 87.9 msec. After PA, VA conduction was abolished in five of 13 patients due to onset of retrograde block in the AV node; in seven of 13, VA block occurred at a longer paced CL after PA (344.2 +/- 51.2 msec vs 477.1 +/- 93.2 msec). In one patient, PA did not affect VA conduction. PA invariably produced prolongation in the VA interval at comparable CL of pacing. With ventricular premature stimulation, the retrograde H2A2 intervals during the control period were short (less than 50 msec) in seven of 13, intermediate (60-100 msec) in three of 13 and long (greater than 100 msec) in three of 13 cases. PA either abolished H2A2 conduction (H2 but no A2) or prolonged the H2A2 intervals by 5-20 msec in most cases in this series. The data suggest that i.v. PA almost uniformly depresses retrograde AV nodal conduction in the intact human heart. This depressant response to PA is not indicative of presence of partial or complete AV nodal bypass tracts.
Overestimation of pediatric cardiac output by thermal indicator loss.
Authors: Maruschak G F , Potter A M , Schauble J F , Rogers M C
Published: June 2011

The accurate measurement of pediatric cardiac output by thermodilution requires that the quantity of cold indicator introduced into the central circulation be known. This study defines an important source of error in the correction factor for the amount of heat gained by small volumes of cold injectate during passage through pediatric catheter systems. This error may result in significant overestimation of cardiac output (as much as 59%) when blood at body temperature is withdrawn into the injection lumen of the pediatric catheter before the injection.
Studies of amiodarone during experimental myocardial infarction: beneficial effects on hemodynamics and infarct size.
Authors: DeBoer L W , Nosta J J , Kloner R A , Braunwald E
Published: June 2011

The effect of amiodarone was investigated in a canine model of myocardial infarction. The left anterior descending coronary artery was occluded in 24 anesthetized dogs. After 15 minutes of coronary artery occlusion, the ischemic myocardium at risk of necrosis was determined by labeling the heart with technetium-99m-labeled human albumin microspheres injected into the systemic circulation through the left atrium, and the dogs were than randomized to either a saline-treated control group (n = 13) or an amiodarone-treated group (n = 11) that received i.v. amiodarone, 10 mg/kg, administered in a single bolus 30 minutes after coronary artery occlusion. Myocardial infarct size was determined directly after 6 hours of coronary occlusion by incubation of sections of myocardium in triphenyltetrazolium chloride, a dehydrogenase stain, and expressed as a percentage of left ventricle below occlusion. Autoradiography of the stained myocardial sections was performed to determine the ischemic myocardium at risk of necrosis, which was similar in the control and amiodarone-treated groups (31.8 +/- 2.8% vs 32.5 +/- 3.3% of the left ventricle, respectively). In the amiodarone-treated group, only 67.1 +/- 8.4% of the myocardium at risk became necrotic; in the control group, 97.5 +/- 7.7% of the myocardium at risk became necrotic (p less than 0.01), representing 21.8 +/- 3.5% vs 31.1 +/- 2.8% of the left ventricle below occlusion, respectively (p less than 0.025). Amiodarone decreased heart rate, contractility and afterload. Its beneficial action on infarct size is related presumably to reduced myocardial oxygen demand.
The role of right ventricular systolic dysfunction and elevated intrapericardial pressure in the genesis of low output in experimental right ventricular infarction.
Authors: Goldstein J A , Vlahakes G J , Verrier E D , Schiller N B , Tyberg J V , Ports T A , Parmley W W , Chatterjee K
Published: June 2011

To elucidate the pathophysiology of severe right ventricular infarction (RVI), isolated RVI was produced in 15 dogs with the pericardium intact or open. After RVI in dogs with the pericardium intact, RV systolic pressure decreased by 27%, aortic pressure by 29% and cardiac output by 34%. RV transmural pressure, RV end-diastolic size and intrapericardial pressure increased, left ventricular transmural pressure and end-diastolic size decreased and the diastolic pressures equalized. Pericardiotomy after RVI resulted in increased ventricular transmural pressures and diastolic size, improved cardiac output and resolution of equalized diastolic pressures. RVI in dogs with the pericardium open resulted in similar changes, but of lesser magnitude and without equalization of diastolic pressures. These results indicate that reduced left ventricular preload due to impaired RV systolic function contributes to low cardiac output in RVI. Elevated intra-pericardial pressure further reduced left ventricular preload and produces equal diastolic pressures.
Gamma camera quantitation of thallium-210 redistribution at rest in a dog model.
Authors: Steingart R M , Bontemps R , Scheuer J , Yipintsoi T
Published: June 2011

Defects seen at rest on thallium-201 (201TI) scintigraphy can disappear over time. We obtained sequential 5-minute scans over 127 +/- 9.4 minutes in seven open-chest dogs with fixed, stable regional flow reductions (normal zone flow 0.76 +/- 0.09 ml g-1/min, ischemic zone flow 0.49 +/- 0.04 ml g-1 min [mean +/- SEM], p less than 0.05) as determined by microsphere injection. Sequential 5-minute scans were obtained after i.v. injection of 1.5 mCi of 201TI. Data were stored in a 64 x 64 pixel computer matrix. Qualitatively, defects that showed redistribution were seen in all dogs. Quantitatively, greater count loss from peak activity distinguished the normal zone, but overlap was great. Alternate quantitative methods using background subtraction altered the characteristics of the time-activity curves, but did not enhance the separation of ischemic from normal zones. Patterns of 201TI redistribution from gamma camera imaging are profoundly influenced by the method of quantitation. No single method of quantitative analysis separated ischemic from normal zones in all dogs. The clinical significance of patterns at rest requires redefinition.
The phase image: its relationship to patterns of contraction and conduction.
Authors: Botvinick E , Dunn R , Frais M , O'Connell W , Shosa D , Herfkens R , Scheinman M
Published: June 2011

To determine the relationship of phase changes and abnormalities of ventricular contraction and conduction, we performed phase image analysis of blood pool scintigrams in 29 patients. Eleven patients had no evidence of blood pool contraction or ECG conduction abnormalities, four had contraction abnormalities, seven had abnormal conduction and seven had abnormalities of both variables. The phase delay generally related to the degree of contraction abnormality. The mean phase delay in hypokinetic segments differed from that in normokinetic segments in the same patient (p less than 0.025), the phase delay of akinetic and dyskinetic segments differed from that in normokinetic segments (p less than 0.001) and the phase delay in dyskinetic segments differed from that in akinetic segments (p less than 0.005), but there was a significant overlap in the phase delay in normal and hypokinetic segments. Also, in patients with conduction abnormalities, the minimal associated regional phase delay presented a phase dispersion and a pattern of contraction consistent with the pattern of conduction and different from normal. A single study performed both at rest and with stress demonstrated the effect of heart rate on phase assessment and confirmed the independent effects of contraction and conduction on phase delay. Acquisition and analytic methods should add significantly to the resolution of the phase method.
The role of hydralazine therapy for pulmonary arterial hypertension of unknown cause.
Authors: Lupi-Herrera E , Sandoval J , Seoane M , Bialostozky D
Published: June 2011

Hydralazine was administered acutely to 12 patients who had pulmonary arterial hypertension of unknown cause. All of the patients were studied at rest and nine during exercise. On the basis of hydralazine response at rest, the patients were divided in two groups. In six patients (group A), pulmonary arteriolar resistance (Rp) decreased from 8.4 +/- 1.4 to 4.8 +/- 1.4 U/m2 (p less than 0.001), cardiac index (CI) increased from 3.47 +/- 0.3 to 5.86 +/- 0.5 1/min/m2 (p less than 0.005) and systemic resistance (Rs) decreased from 25 +/- 4 to 14 +/- 2 U/m2 (p less than 0.01). The Rp/Rs ratio did not change significantly after hydralazine (0.32 +/- 0.03 vs 0.33 +/- 0.07, NS). In the other six patients (group B), Rs decreased from 25 +/- 2 to 17.0 +/- 1 U/m2 (p less than 0.01), but the other variables did not change significantly. Our results suggest that the pulmonary vasodilatory effect of hydralazine caused a marked reduction in right ventricular afterload in group A. In group B, a marked systemic vasodilatory effect occurred and right ventricular afterload was not reduced. On the basis of the previous hemodynamic response, only group A patients were treated with oral hydralazine (50 mg every 6 hours). Hemodynamic measurements were repeated 48 hours after hydralazine, both at rest and during exercise, as well as 8 months later in five of the six patients in whom the beneficial hemodynamic effects persisted. These data suggest that hydralazine can reduce Rp in selected patients (pulmonary arterial pressure less than 60 mm Hg, Rp less than 15 U/m2 and Rp/Rs ratio less than 0.7) with pulmonary hypertension of unknown cause.
Intravenous hyaluronidase therapy for myocardial infarction in man: double-blind trial to assess infarct size limitation.
Authors: Cairns J A , Holder D A , Tanser P , Missirlis E
Published: June 2011

Patients with their first myocardial infarction not initially complicated by severe atrioventricular block or power failure were given a skin test and then randomized to receive either hyaluronidase or placebo in double-blind fashion. Hyaluronidase, 500 IU/kg i.v., was given every 6 hours for 42 hours. Of the 48 eligible patients, 26 received hyaluronidase and 22 received placebo. The mean CK serum entry was 3140 +/- 2111 mIU/ml (mean +/- SD) in hyaluronidase patients and 3574 +/- 1476 mIU/ml in placebo patients (p less than 0.21). The mean infarct size was 54.6 +/- 35.8 CK gram-equivalents in the hyaluronidase patients and 64.0 +/- 31.1 CK gram-equivalents in the placebo patients (p less than 0.20). Among the 21 patients treated within 6 hours of the onset of infarction, the difference in infarct size was greater (p less than 0.15). There was no significant difference in the incidence of power failure, ventricular arrhythmias, recurrence of ischemic pain, infarct extension or mortality. No benefit of hyaluronidase was demonstrated in this study, which was designed to detect a 50% reduction of infarct size. However, to detect a 20% reduction in infarct size would require a much larger study population.
Detection of mitral ring abscess by two-dimensional echocardiography.
Authors: Nakamura K , Suzuki S , Satomi G , Hayashi H , Hirosawa K
Published: June 2011

M-mode and two-dimensional echocardiographic features of mitral ring abscess are described. A round, dense echo mass between the posterior mitral leaflet and left ventricular posterior wall was demonstrated in long- and short-axis views of the left ventricle. The diagnosis of mitral ring abscess was confirmed at surgery. The superiority of two-dimensional echocardiography over M-mode echocardiography for evaluating patients with mitral ring abscess is also discussed.
Surgery for cardiac complications caused by endocardial mural fibrin deposits in a hypereosinophilic syndrome.
Authors: Fournial G , Schlanger R , Berthoumieu F , Pris J , Marco J , Eschapasse H
Published: June 2011

A 31-year-old man presented with rapid onset of intractable congestive heart failure during the course of chemotherapy for eosinophilic leukemia. Patients with a hypereosinophilic syndrome usually die from complications of eosinophilic infiltration and fibrosis in target organs. The resulting cardiac lesions are a cause of death among these patients. Surgical intervention enabled our patient to survive the immediate medical crisis and has prolonged his life.
Computerized axial tomography of the chest for visualization of "absent" pulmonary arteries.
Authors: Sondheimer H M , Oliphant M , Schneider B , Kavey R E , Blackman M S , Parker F B
Published: June 2011

To expand the search for central pulmonary arteries in six patients with absence of cardiac-pulmonary continuity, computerized axial tomography (CAT) of the chest was performed. The CAT scans were compared with previous arteriograms and pulmonary vein wedge angiograms. Three patients with type IV truncus arteriosus were studied, and none had a central, right or left pulmonary artery on CAT scan. However, two patients with tetralogy of Fallot with pulmonary atresia and a patent ductus arteriosus to the right lung demonstrated the presence of a left pulmonary artery. In addition, one child with truncus arteriosus with "absent" left pulmonary artery demonstrated a left pulmonary artery on the CAT scan. The CAT scan may therefore enhance our ability to search for disconnected pulmonary arteries in children with complex cyanotic congenital heart disease.
Myocardial infarct extension: incidence and relationship to survival.
Authors: Baker J T , Bramlet D A , Lester R M , Harrison D G , Roe C R , Cobb F R
Published: June 2011

Myocardial infarct extension, defined as reelevation or reappearance of creatine phosphokinase-MB (CK-MB) 48 hours after the onset of symptoms, was evaluated prospectively in 56 consecutive patients with acute myocardial infarction. Myocardial infarct extension occurred in eight patients (14%). The sensitivity, specificity and predictive accuracy in the diagnosis of myocardial infarct extension were 63%, 85% and 42%, respectively, for recurrent chest pain requiring morphine; 50%, 65% and 19% for recurrent ST-segment elevation on routine 12-lead ECGs; and 88%, 63% and 28% for reelevation of total CK. Three of the eight episodes of extension were clinically silent. Four of eight patients (50%) with extension died, compared with one of 46 patients (2%) without extension (p = 0.0009). CK-MB persisted for 72 hours or longer in 16 patients and identified seven of eight patients who subsequently had infarct extension. We conclude that myocardial infarct extension is an infrequent complication of acute myocardial infarction and is associated with a very high mortality rate. Persistence of CK-MB for 72 hours or more identifies a subgroup of patients at high risk for subsequent infarct extension and death.
Fire fighting and coronary heart disease.
Authors: Dibbs E , Thomas HE JrU  , Weiss S T , Sparrow D
Published: June 2011

Some studies suggest that fire fighters are at a higher risk of developing coronary heart disease than are males in the general population. We followed 1646 men for 10 years to determine the incidence of coronary heart disease. Subjects were participants of the Normative Aging Study, a longitudinal study of aging. Comparison of fire fighters (n = 171) and non-fire fighters (n = 1475) showed no significant difference in the incidence rates of coronary heart disease. Comparison of the groups regarding baseline risk factors revealed no material difference. These data suggest that fire fighters do not have an excess risk of coronary heart disease.
Release of atherosclerotic debris after transluminal angioplasty.
Authors: Block P C , Elmer D , Fallon J T
Published: June 2011

To determine if there is release of endothelial cells or plaque contents after percutaneous transluminal angioplasty, effluent from atherosclerotic segments of the aorta and iliac arteries of rabbits were collected before and after angioplasty. No endothelial cells or cholesterol plates were identified in the preangioplasty effluents. Only a few single endothelial cells and cholesterol crystals were found in effluents after angioplasty. We conclude that embolization of endothelial fragments and cholesterol plates occurs during angioplasty, but only to a minor degree, and is probably not clinically important.
Improved visualization of aortopulmonary collateral arteries by abdominal aortic compression during angiography.
Authors: Moll J N , Santos M A , Drumond C , Romao N , Murad M , Reis N B
Published: June 2011

Increased filling of aortopulmonary collateral arteries occurs when the descending aorta is obstructed distal to their origin. We used this fact to develop a simple, safe technique for improving angiographic visualization of these arteries. The abdominal aorta is manually compressed against the spine during injection of contrast medium. A slight reflex bradycardia resulted, which probably also enhanced filling of the collateral arteries. In eight infants and children with either pulmonary atresia and a ventricular septal defect or truncus arteriosus communis, excellent visualization was consistently achieved without complication.
Myocardial protection through cold cardioplegia with potassium or diltiazem. Experimental evidence that diltiazem provides better protection even when coronary flow is impaired by a critical stenosis.
Authors: Vouhé P R , Hélias J , Robert P , Grondin C M
Published: June 2011

Intermittent aortic root infusion of a cold solution containing either potassium chloride (KCl) or diltiazem was performed in 32 dogs during a 2-hour aortic clamping. Half of the dogs in each group had a critical stenosis created on the circumflex artery before cardiopulmonary bypass. Global left ventricular (LV) function was determined 1 hour after bypass by means of LV pressure, peak dP/dt, LV end-diastolic pressure, cardiac and stroke work indexes. Regional function was assessed through microcrystals in the areas of the circumflex and left anterior descending coronary arteries. LV pressure decreased in all dogs, but more so with the KCl solution (p = 0.02). The stenosis had no specific effect on LV pressure, but affected peak positive dP/dt (p = 0.007) and LV end-diastolic pressure (p less than 0.0001). Cardiac and stroke work indexes decreased more in the KCl group than in the diltiazem group (p less than 0.002) with or without stenosis. Both positive and negative dP/dt were affected by the type of solution (a greater decrease with KCl), but the narrowing affected only the positive dP/dt. Regional LV function remained unchanged in the absence of a narrowing and was depressed equally in dogs with a narrowing whether they received KCl or diltiazem. Overall LV function appeared to be better preserved with diltiazem, with or without impairment of circumflex flow.
Left ventricular diastolic capacity in man.
Authors: Flessas A P , Ryan T J
Published: June 2011

Plasma volume expansion with 500 ml of low-molecular-weight dextran was used in 27 patients (nine normal subjects, 13 patients with ischemic heart disease, four with aortic stenosis and one with cardiomyopathy) to increase left ventricular end-diastolic pressure (LVEDP) from a control value of 12.4 +/- 7.0 mm Hg (mean +/- SD) to 23.3 +/- 7.0 mm Hg and end-diastolic volume (EDV) from 84.0 +/- 23.8 ml/m2 to 97.6 +/- 22.9 ml/m2. EDV-LVEDP curves constructed for 12 patients from multiple angiograms at progressively increasing LVEDPs during plasma volume expansion showed an initial part where EDV increased in parallel with LVEDP and a final steep or perpendicular part where EDV increased minimally or not at all as LVEDP exceeded 20 mm Hg. Exponential equations were used to fit diastolic volume-pressure data obtained with catheter-tip manometers in seven patients: the exponential constant, k, was 0.012-0.044 ml-1 and was inversely related to EDV (Spearman's rank correlation coefficient = -1). For comparable EDV, there were no differences in k values between normal subjects and patients with a variety of heart diseases.
Concealed reentry: a mechanism of atrioventricular nodal alternating Wenckebach periodicity.
Authors: Littmann L , Svenson R H
Published: June 2011

Alternating WEnckebach periodicity is generally believed to reflect bilevel block due to horizontal electrophysiologic dissociation in the conducting tissues. We describe a case of atrial pacing-induced atrioventricular nodal alternating Wenckebach periodicity with concealed reentry in a longitudinally dissociated AV conduction system. Three observations support this unique mechanism: Concealed reentry occurred during the course of alternating Wenckebach periodicity; it could be invoked to explain the peculiar conduction patterns in this patient; and alternative mechanisms did not explain the alternating Wenckebach periods. Our findings also indicate that long conduction times during 2:1 block can be due to concealed reentry rather than concealed antegrade conduction, and participation in the echo process of a retrograde pathway with electrophysiologic characteristics of an atrioventricular nodal bypass tract does not exclude manifest and concealed reentry at a subatrial level.
Transaortic occlusion of collateral arteries to the lung by detachable valved balloons in a patient with tetralogy of Fallot.
Authors: Grinnell V S , Mehringer C M , Hieshima G B , Stanley P , Lurie P R
Published: June 2011

A 5-year-old boy with tetralogy of Fallot, near-atresia of the right ventricular outflow tract and large collateral arteries to the lungs underwent an infundibulectomy without closure of the ventricular septal defect. Further surgery required preliminary reduction of the collateral circulation. The collateral arteries were successfully occluded by metrizimide-filled balloons. There was no change in arterial oxygen saturation, nor were there any complications. This new technique has significant advantages over existing alternatives.
Effects of inotropic and chronotropic stimuli on acute myocardial ischemic injury. I. Studies with dobutamine in the anesthetized dog.
Authors: Rude R E , Izquierdo C , Buja L M , Willerson J T
Published: June 2011

The effect of i.v. dobutamine on acute myocardial ischemic injury was assessed in 22 anesthetized dogs subjected to serial 10-minute occlusions of the left anterior descending coronary artery. The severity of ischemic injury was determined by mass spectrometric measurement of the increase in intramural carbon dioxide tension (delta PmCO2) in the ischemic zone. In the time protocol 1 dogs, dobutamine, 20 micrograms/kg/min, infused between the control and final occlusion, significantly increased both heart rate (HR) and left ventricular (LV) dP/dt; delta PmCO2 was significantly higher during the dobutamine infusion that during control occlusion (76 +/- 21 vs 56 +/- 13 mm Hg, p less than 0.01). The nine protocol 2 dogs were atrially paced at a HR of 20--30 beats/min above baseline values during the control occlusion and received dobutamine (12.6 +/- 7.8 micrograms/kg/min) at doses necessary to attain an equal HR (mean 149--154 beats/min) during the last occlusion. Although LV dP/dt was higher after dobutamine, delta PmCO2 was similar during the two occlusions. Protocol 3 dogs (n = 4) received lower doses of dobutamine (5.6 +/- 3.2 micrograms/kg/min) to produce an increase in LV dP/dt, but not in HR compared with baseline values; delta PmCO2 was similar during control and dobutamine occlusions. There were no major change in arterial or left atrial pressures. Rate-pressure product, an indirect measurement of myocardial oxygen consumption, was increased only by the higher doses of dobutamine in protocol 1. Thus, inotropic stimulation with dobutamine during coronary occlusion does not cause important augmentation of acute myocardial ischemic injury in the nonfailing heart unless HR is increased simultaneously.
The effects of oral hydralazine on right ventricular end-diastolic pressure in patients with right ventricular failure.
Authors: Rubin L J , Handel F , Peter R H
Published: June 2011

Hydralazine reduces pulmonary vascular resistance in patients with primary and secondary pulmonary hypertension, but the effects on right ventricular function of a change in resistance without a reduction in pulmonary arterial pressure are not known. We evaluated the hemodynamic effects of hydralazine, 50 mg, administered orally every 6 hours for 48 hours in 14 patients with right ventricular failure and pulmonary hypertension resulting from various causes. Hydralazine reduced mean right ventricular end-diastolic pressure from 17.4 +/- 5.6 to 11.6 +/- 5.3 mm Hg (p less than 0.001) and increased cardiac output and stroke volume by more than 40%. In nine patients who had no change in mean pulmonary arterial pressure after hydralazine, total pulmonary resistance decreased from 15.9 +/- 6.0 to 10.6 +/- 4.3 (p less than 0.001) and cardiac index increased from 2.07 +/- 0.51 to 2.97 +/- 0.91 (p less than 0.005). There was a close correlation between the reductions in total pulmonary resistance and right ventricular end-diastolic pressure (r = 0.73)). These data suggest that hydralazine can increase cardiac output and reduce right ventricular end-diastolic pressure even when pulmonary arterial pressure remains unchanged.
Comparison of cardiovascular response to combined static-dynamic effort, postprandial dynamic effort and dynamic effort alone in patients with chronic ischemic heart disease.
Authors: Hung J , McKillip J , Savin W , Magder S , Kraus R , Houston N , Goris M , Haskell W , DeBusk R
Published: June 2011

The cardiovascular responses to combined static-dynamic effort, postprandial dynamic effort and dynamic effort alone were evaluated by upright bicycle ergometry during equilibrium-gated blood pool scintigraphy in 24 men, mean age 59 +/- 8 years, with chronic ischemic heart disease. Combined static-dynamic effort and the postprandial state elicited a peak cardiovascular response similar to that of dynamic effort alone; work load 643 +/- 156 and 638 +/- 161 vs 650 +/- 153 kg-m/min, respectively; heart rate 147 +/- 14 and 145 +/- 14 vs 143 +/- 17 beats/min; systolic pressure 195 +/- 26 and 200 +/- 25 vs 197 +/- 25 mm Hg; and rate-pressure product 286 +/- 48 and 292 +/- 55 vs 282 +/- 52. Heart rate, intraarterial systolic and diastolic pressures, rate-pressure product and ejection fraction were similar for the three test conditions at the onset of ischemia and at peak effort. The prevalence and extent of exercise-induced ischemic left ventricular dysfunction, ST-segment depression, angina pectoris and ventricular ectopic activity were also similar during the three test conditions. Direct and indirect measurements of systolic and diastolic blood pressure were highly correlated. The onset of ischemic ST-segment depression and angina pectoris correlated as strongly with heart rate alone as with the rate-pressure product during all three test conditions. The cardiovascular response to combined static-dynamic effort and to postprandial dynamic effort becomes more similar to that of dynamic effort alone as dynamic effort reaches a symptom limit. If significant ischemic and arrhythmic abnormalities are absent during symptom-limited dynamic exercise testing, they are unlikely to appear during combined static-dynamic or postprandial dynamic effort. This simplifies, the task of formulating guidelines for physical effort in patients with chronic ischemic heart disease, especially in providing "clearance" to perform avocational and vocational tasks involving combined static-dynamic and postprandial dynamic effort.
Hypothermic coronary venous phased retroperfusion: a closed-chest treatment of acute regional myocardial ischemia.
Authors: Meerbaum S , Haendchen R V , Corday E , Povzhitkov M , Fishbein M C , Y-Rit J , Lang T W , Uchiyama T , Aosaki N , Broffman J
Published: June 2011

Hypothermic synchronized retroperfusion (HSRP) was applied in closed-chest dogs after acute coronary occlusion to determine whether this intervention can significantly retard the otherwise rapidly developing irreversible ischemic injury. The left anterior descending coronary artery (LAD) was occluded for 3 hours in 22 dogs and for 6 hours in 16 dogs. Starting 30 minutes after occlusion, HSRP was applied during maintained coronary occlusion in 21 dogs. The remaining dogs served as untreated controls. Arterial blood was cooled to 20 degrees C and retroperfused in diastole into the regional coronary veins. Hemodynamics, contrast cineangiography and two-dimensional echocardiography were measured sequentially. Glycogen-depleted ischemic areas and necrotic zones were delineated in transverse slices of the left ventricle. Untreated controls dogs further deteriorated; in contrast, HSRP between 30 minutes and 3- and 6-hour LAD occlusion significantly reduced the rate-pressure product (21.3 +/- 4.0% or 26.8 +/- 8.2%) and left ventricular end-diastolic pressure (39.5 +/- 9.5% or 51.4 +/- 7.7%) and increased ejection fraction (28 +/- 17% and 33 +/- 2.0%). HSRP caused no arrhythmias and led to much less necrosis of ischemic myocardium in the treated 3- or 6-hour occlusion series (7.4 +/- 2.7% or 28.9 +/- 12.6%) than in respective untreated controls (47.1 +/- 8.9% and 72.3 +/- 5.9%). Moderately hypothermic closed-chest phased retroperfusion appears to protect reversibly injured ischemic myocardium and improve cardiac function. Such treatment may be particularly suitable in the earliest stages of evolving myocardial infarction, when maintenance of myocardial viability is essential for preservation of jeopardized myocardium while awaiting coronary bypass revascularization or nonsurgical thrombolytic reperfusion.
The electrocardiogram in epidemiologic investigations. A new classification system.
Authors: Pipberger H V , Simonson E , Lopez E A , Araoye M A , Pipberger H A
Published: June 2011

A new coding system for ECG abnormalities was developed, based on Frank's orthogonal ECG leads. In contrast to other systems, such as the Minnesota Code (MC), the new system was based on data collected prospectively in a cooperative study of 5031 records. The records were classified solely on the basis of non-ECG information. A record sample from normal women was also available. The large data base allowed stratification of ECG criteria according to sex and race. ECG criteria were determined at two levels of sensitivity and specificity. Specificity was 80-100% at the first level and 90-90% at the second. The new system has fewer criteria than other codes, which leads to reduction of coding errors and coding time. For common problems in differential diagnosis, optional criteria were included. A computer program for automated coding was also developed.
Diagnostic accuracy of exercise ECG lead systems in clinical subsets of women.
Authors: Guiteras P , Chaitman B R , Waters D D , Bourassa M G , Scholl J M , Ferguson R J , Wagniart P
Published: June 2011

The diagnostic accuracy of 14-lead exercise electrocardiography was evaluated in 112 women who had no history of myocardial infarction and underwent coronary angiography. The sensitivity of ST-segment displacement of 0.1 mV or more in any of 14 ECG leads was 0.79 for coronary artery stenosis of at least 70%; the specificity was 0.66. Results were similar using bipolar ECG leads CC5 and CM5 or 11 standard ECG leads. The ST-segment shifts that occurred only during exercise were associated with a 77% false-positive rate (10 of 13). Downsloping ST-segment depression did not provide more diagnostic information than horizontal ST-segment depression in the three clinical subsets of women. In women with typical angina pectoris, ST-segment depression of at least 0.15 mV for 0.08 second after the J point or a final treadmill time less than 360 seconds was predictive of proximal left or multivessel coronary artery disease. In the women with probable angina or nonspecific chest pain, this finding was not of diagnostic value. ST-segment elevation of 0.1 mV or more in leads V1-2 or a VL predicted proximal stenosis of at lest 80% in the left anterior descending coronary artery in all six women with typical angina pectoris. Maximal exercise testing in women with typical angina provides important diagnostic information when 11 standard ECG leads are recorded. In women with probable angina or nonspecific chest pain, diagnostic exercise testing is less useful and bipolar leads CC5 and CM5 are sufficient for most clinical purposes.
Slow late myocardial clearance of thallium: a characteristic phenomenon in coronary artery disease.
Authors: Sklar J , Kirch D , Johnson T , Hasegawa B , Peck S , Steele P
Published: June 2011

We extended the quantitative seven-pinhole method to follow the dynamics of thallium redistribution after exercise. We observed a pattern of slow late thallium clearance that appears to be characteristic of myocardium supplied by obstructed coronary arteries. In 28 subjects, quantitative thallium scintigrams (seven-pinhole tomography, circumferential count profiles) and blood samples for thallium concentration were taken immediately, 2 hours and 4 hours after maximal treadmill exercise. Twenty subjects had coronary artery disease (CAD) and eight were normal. The rate of thallium clearance from the blood (TCB) was compared with the rate of thallium clearance from each segmental region of myocardium (TCM, derived by ratioing corresponding segments of the absolute circumferential count profiles) between the 2- and 4-hour images. In seven of the eight normal subjects, TCM exceeded TCB in all regions of all images (specificity 88%). Seventeen of the 20 CAD patients had at least one region where TCM was less than TCB (sensitivity 85%). Of the 13 patients with multivessel CAD, 11 had multiple regions with TCM less than TCB. Using this criterion, we detected 31 of 39 obstructed coronary arteries. Of the 37 regions that were abnormal by this analysis, 30 corresponded to obstructed coronary arteries. In contrast, while conventional circumferential count profile analysis also was abnormal in 17 of the 20 CAD patients, it diagnosed multivessel CAD in only five of the 13 patients that had it. These results show that slow late thallium clearance from myocardium is characteristic of regions of myocardium supplied by diseased coronary arteries and that observation of this phenomenon may improve diagnostic sensitivity for the presence of multivessel CAD.
Noninvasive identification of initial site of abnormal ventricular activation by least-square phase analysis of radionuclide cineangiograms.
Authors: Turner D A , Von Behren P L , Ruggie N T , Hauser R G , Denes P , Ali A , Messer J V , Fordham E W , Groch M W
Published: June 2011

Least-square phase analysis (LSPA) of radionuclide cineangiograms demonstrates the sequence of onset of inward ventricular movement noninvasively. To validate the method and explore its ability to identify abnormal initial sites of ventricular activation, LSPA was applied to 14 patients with pacemakers (one with electrodes in two locations) (group 1) and three patients with recurrent ventricular tachycardia (VT) (group 2) who had undergone electrophysiologic endocardial mapping. The segment in which the site of initial ventricular activation was located was correctly identified in 13 of 15 paced studies and in two of three group 2 patients during VT. Pacing increased the duration of spread of onset of inward ventricular movement, and the duration of spread of onset correlated well with the duration of the QRS (r = 0.80). The sequence of onset of inward ventricular movement during VT was similar to the sequence of depolarization in all three group 2 patients. These preliminary results suggest that the sequence of onset of ventricular contraction as depicted by LSPA is a valid representation of the actual contraction sequence and that LSPA or radionuclide cineangiography correctly identifies abnormal sites of initial ventricular activation.
Should a fixed external reference system be used to analyze left ventricular wall motion?
Authors: Clayton P D , Jeppson G M , Klausner S C
Published: June 2011

To investigate whether a fixed external reference system should be used to most accurately describe regional left ventricular wall motion, we used vectors to analyze a simple model of ventricular contraction. If measured in a fixed external reference system, motion of implanted radiopaque midwall markers may contain translational as well as contractile components. Therefore, comparisons of different reference systems that use marker motion measured in a fixed reference system as a standard will be biased unless proper corrections are included. We conclude that evidence to data does not indicate that the use of a fixed reference system is superior to other methods for analyzing regional ventricular wall motion.
Medical management of the patient with angina pectoris: an overview of the problem.
Authors: Reeves T J
Published: June 2011

The medical management of angina pectoris requires a comprehensive approach to the patient and his family, including attention not only to established physiologic and pharmacologic principles, but also to the emotional aspects of his illness. When comprehensive management is systematically and rigorously applied to the patient with angina pectoris, excellent relief of the symptoms of angina pectoris can be achieved in a high percentage of patients, although there are significant numbers of patients who are refractory to the most intensive management using presently available drugs. The same fundamental principles of care apply to patients with coronary heart disease who undergo aortocoronary bypass surgery and to those treated medically.
The Veterans Administration Cooperative Study of stable angina: current status.
Authors: Takaro T , Hultgren H N , Detre K M , Peduzzi P
Published: June 2011

The current status of the Veterans Administration Cooperative Study of the effect of surgery on survival in patients with stable angina is presented. The outcome in 686 adult males randomly allocated to medical or surgical treatment groups in 1972-1974 was studied in subgroups of patients classified by invasive (arteriographic) and noninvasive risk factors. In 91 patients with left main lesions reducing the luminal diameter 50% or more, surgery significantly improved survival in the two-thirds characterized as middle or high risk by four simple noninvasive predictors of prognosis (New York Heart Association functional classification III or IV, history of myocardial infarction, history of hypertension, and ST-segment depression on the resting baseline ECG as assessed on a centralized reading). Patients with three-vessel disease and no significant disease of the left main coronary artery also had better survival rates when treated surgically. However, this was statistically significant at 6 years only in the 10 hospitals in which the aggregate operative mortality was 3.3%. Patients without left main lesions were also categorized by four noninvasive predictors of risk. Categorizing such patients into roughly equal groups of high, middle, and low risk identified a high-risk group, in which surgery was associated with statistically improved survival, and low- and middle-risk groups in which it was not. The use of both invasive and noninvasive factors to assess risk in patients with chronic stable angina pectoris provided greater predictive power than either angiography or noninvasive factors alone.