bluuebunny/crossref_metadata_2025 huggingface dataset:
Noninvasive evaluation of exercise training in college-age men.
Authors: Adams T D , Yanowitz F G , Fisher A G , Ridges J D , Lovell K , Pryor T A
Published: June 2011

The purpose of this study was to assess noninvasively the effects of intense aerobic training on cardiac structure and function in a group of healthy, college-age men (25 experimental and 11 control, mean age 22 years). Echocardiographic, electrocardiographic (ECG), and fitness measurements were obtained before and after a 3-month endurance training program and compared with similar measurements obtained in nonexercising subjects. The supervised training program consisted of 50-minute jogging sessions 5 days a week at 85% of maximal heart rate. Compared with the control group, echocardiography after training showed an increase in left ventricular (LV) end-diastolic dimension (p less than 0.05). LV posterobasal wall thickness, septal wall thickness and ejection fraction did not change significantly. ECG measurements revealed a decrease in resting heart rate (p less than 0.05) and an increase in R-wave voltage in leads V5 and V6 (p less than 0.01). The measured maximal oxygen consumption increased by 16% (p less than 0.001). These data indicate that intense aerobic training in college-age men results in a significant increase in resting LV end-diastolic dimension and volume. The increase in maximal stroke volume associated with exercise training may be partially explained by these changes in cardiac dimensions.
Acute vasodilator therapy increases renal clearance of digoxin in patients with congestive heart failure.
Authors: Cogan J J , Humphreys M H , Carlson C J , Benowitz N L , Rapaport E
Published: June 2011

We studied the effect of vasodilator therapy on renal digoxin clearance in patients with chronic congestive heart failure. Intravenous administration of nitroprusside or hydralazine to eight patients with severe heart failure produced the expected increase in cardiac output and a decrease in central circulatory pressure. Renal clearance of sodium para-aminohippurate and estimated renal blood flow increased without a change in glomerular filtration rate. Total renal clearance of digoxin increased by 50% during vasodilator therapy. Thus, acute administration of vasodilator increases renal digoxin clearance without changing glomerular filtration rate, suggesting an increase in tubular secretion of digoxin. Long-term vasodilator therapy may alter the maintenance dosage of digoxin required for optimal treatment of patients in congestive heart failure.
Characteristics of the resuscitated out-of-hospital cardiac arrest victim with coronary heart disease.
Authors: Goldstein S , Landis J R , Leighton R , Ritter G , Vasu C M , Lantis A , Serokman R
Published: June 2011

The clinical entry characteristics and medical history of 142 resuscitated out-of-hospital cardiac arrest victims with coronary heart disease were studied in order to identify factors that affect their long-term survival. The cardiac arrest event was classified as being secondary to an acute myocardial infarction (AMI) in 44% (62 of 142), an ischemic event (IE) in 34% (49 of 142) and a primary arrhythmic event (PAE) in 22% (31 of 142). The majority of patients in all groups had a history of angina pectoris. Twenty-seven percent of the AMI, 55% of the IE, and 71% of the PAE patients had a history of infarction. Ten percent of the AMI, 31% of the IE, and 55% of the PAE had used digitalis before their cardiac arrest. Cardiac arrest was the first cardiac event in 35% of the AMI, 16% of the IE and 6% of the PAE patients. One year after arrest, 89% of the AMI, 80% of the IE and 71% of the PAE were alive (p less than 0.01). Covariate analysis for more than 40 variables indicates that a high-risk group included 22% (31 of 142) of the cardiac arrest victims had 1- and 2-year survival rates of 71% and 55%, respectively, and was characterized as having used digitalis before arrest, experiencing blood urea nitrogen elevation and pulmonary congestion during the hospitalization for the event, and classification of the cardiac arrest event as a PAE. A low-risk group comprised 78% (111 of 142) of the survivors and had 1- and 2-year survival rates of 85% and 69%, respectively. These data indicate that cardiac arrest due to coronary heart disease is secondary to several mechanisms related to subsequent survival.
Left fascicular blocks during right-heart catheterization using the Swan-Ganz catheter.
Authors: Castellanos A , Ramirez A V , Mayorga-Cortes A , Pefkaros K , Rozanski J J , Sprung C , Myerburg R J
Published: June 2011

During insertion of Swan-Ganz catheters, mechanical right bundle branch block occurred in association with left posterior fascicular block in two patients and with left anterior fascicular block in two. None of the four patients had acute myocardial infarction or acute (spontaneous or iatrogenic) pulmonary disease. In two cases, electrophysiologic studies demonstrated the coexistence of intra- and infra-Hisian conduction delays and blocks. Although the right bundle branch block may have resulted from injury to the central or peripheral right branch, the left fascicular blocks could not be explained by direct trauma to these left-sided structures. Our findings support the recent clinical and experimental reports that show that left fascicular block (as well as right bundle branch block) may be due to lesions involving the His bundle; presumably because of longitudinal dissociation of this structure affecting the transverse interconnections. In one patient, 2:1 intra-Hisian block may have coexisted with bradycardia-dependent (phase 4) right bundle branch block. More studies are required to determine the implications of catheter-induced conduction disturbances in other clinical settings, such as acute myocardial infarction.
The 24-hour ambulatory blood pressure profile with verapamil.
Authors: Gould B A , Mann S , Kieso H , Subramanian V B , Raftery E B
Published: June 2011

The blood pressure response in hypertensive subjects to chronic treatment with verapamil, a calcium antagonist (or, more precisely, a slow-channel inhibitor), was studied using the Oxford system for continuous monitoring of intraarterial blood pressure. Sixteen patients underwent continuous monitoring over a 48-hour period before and after at least 6 weeks of therapy (dose range 120-160 mg three times daily). Each monitoring period included physiologic tests designed to show the effects of different types of exercise. Verapamil produces a consistent reduction of blood pressure over 24 hours, but particularly during the day. Heart rate was similarly reduced. There was no evidence of postural hypotension, and the absolute responses to dynamic and isometric exercise were reduced. The degree of reduction of the blood pressure was consistent, suggesting that slow-channel inhibitors may be appropriate for antihypertensive therapy.
Coronary artery disease mortality in relatives of hypertriglyceridemic school children: the Muscatine study.
Authors: Schrott H G , Clarke W R , Abrahams P , Wiebe D A , Lauer R M
Published: June 2011

From 2655 healthy school children participating in the 1973 and 1975 Muscatine Coronary Risk Factor School surveys, two groups of index cases were selected for a detailed family study of coronary mortality: a group with fasting triglyceride levels greater than the ninetieth percentile on both surveys (n = 75) and a group with triglyceride levels less than the tenth percentile on both surveys (n = 47). Coronary mortality in adult (age 30 years or older) first- and second-degree relatives was not different between the two groups. When the families of the high-triglyceride group was further subdivided based on the cholesterol percentile of the index child, greater coronary mortality was observed in the relatives of index cases with high cholesterol (higher than the seventy-fifth percentile). This study suggests that family members of children with elevated triglyceride and low cholesterol levels do not have excess coronary mortality.
Electrophysiologic characteristics of human ventricular and Purkinje fibers.
Authors: Dangman K H , Danilo P , Hordof A J , Mary-Rabine L , Reder R F , Rosen M R
Published: June 2011

We studied the electrophysiologic characteristics of ventricular muscle and Purkinje fibers from the hearts of five patients undergoing cardiac transplantation. All five patients had congestive failure and coronary artery disease before surgery and were receiving digitalis therapy. Ventricular muscle had a maximal diastolic potential (MDP) of -78 +/- 1 mV (mean +/- SEM), an action potential (AP) amplitude of 104 +/- 2 mV, a phase 0 upstroke velocity (Vmax) of 297 +/- 19 V/sec and an AP duration at 50% repolarization (APD50) of 190 +/- 4 msec. Purkinje fibers had an MDP of -80 +/- 2 mV, an AP amplitude of 107 +/- 2 mV, a Vmax of 388 +/- 25 V/sec and an APD50 of 195 +/- 9 msec. Fibers from infarcted sections of the heart had significantly longer APD than those from noninfarcted, which resulted in marked dispersion of APD in infarcted and adjacent zones. Both epinephrine and ouabain induced delayed after depolarizations in Purkinje fiber. This suggest that delayed after depolarizations and resultant triggered activity can occur in the human ventricle.
Physician practice in the management of patients with uncomplicated myocardial infarction: changes in the past decade.
Authors: Wenger N K , Hellerstein H K , Blackburn H , Castranova S J
Published: June 2011

To determine changes in the patterns of care between 1970 and 1980 for patients with uncomplicated acute myocardial infarction, questionnaires were sent to almost 6000 physicians in 1979 and responses were compared with those of a similar survey taken in 1970. Almost all physicians in 1979 reported the availability and use of an intensive care/coronary care unit facility with continuous electrocardiographic monitoring. Progressive-care facilities are also becoming more widely available. The median length of hospitalization has decreased markedly. Early ambulation and an earlier return to work are more common. There is a high level of informal patient and patient-family counseling about myocardial infarction and its management, both during and after hospitalization, and wider use of educational materials. Most physicians continue to recommend progressive physical activity after hospitalization. The routine prescription of anticoagulant therapy during hospitalization has declined, while prescription of prophylactic antiarrhythmic agents has increased. Nitrate drugs and tranquilizers are routinely prescribed by a large percentage of physicians for their patients with uncomplicated myocardial infarction. Use of standard exercise tests has increased among all physician specialties. The treadmill test is most often used, and testing is typically done 6 weeks after infarction. A significant increase in the availability of and familiarity with exercise testing is characteristic of all medical specialties. Symptoms of new chest pain and palpitations are now considered important enough to warrant the recommendation to report immediately to an emergency room. Other current findings include the routine use of coronary angiography by a large percentage of physicians to evaluate the need for surgical intervention, and the routine posthospitalization prescription by only a small percentage of physicians of aspirin and of nitrate drugs for patients with uncomplicated myocardial infarction.
The effects of cigarette smoke and nicotine on platelet thrombus formation in stenosed dog coronary arteries: inhibition with phentolamine.
Authors: Folts J D , Bonebrake F C
Published: June 2011

This study was undertaken to examine in vivo the effects of cigarette smoke on cyclic reductions in coronary flow due to platelet thrombus formation in the stenosed coronary arteries of anesthetized dogs. The circumflex coronary artery of 21 mongrel dogs was stenosed 60 - 80%, with blood flow measured with an electromagnetic flow probe. After the administration of cigarette smoke, plasma epinephrine was elevated nine times the control level (p less than 0.001) and peak mean blood pressure was elevated one and one-half times control (p less than 0.01). The hematocrit increased several percent (p less than 0.01) with cigarette smoke, although blood gases and pH remained unchanged. In all 21 dogs, spontaneous reductions in coronary blood flow were greatly exacerbated in the stenosed circumflex artery as evidenced by the number of flow reductions, the increased size of the reductions and the rate of flow reduction. Nicotine administered intravenously in doses comparable to those achieved through absorption of cigarette smoke by the lungs provoked similar responses of alpha-adrenergic stimulation and potentiation of the platelet thrombus formation. An alpha-adrenergic antagonist, phentolamine, was given (3 mg/kg) intravenously to inhibit the exacerbated platelet thrombus formation due to cigarette smoke or infused nicotine. In 18 of 21 dogs, an acute occlusive platelet thrombus was prevented 15 minutes after phentolamine and after phentolamine and after a cigarette smoke or nicotine challenge. This study confirms a link between cigarette smoking, platelet formation, and the potential for humans to develop an acute occlusive platelet thrombus in a diseased and stenotic coronary artery.
Echocardiographic detection of left main coronary artery obstruction.
Authors: Rink L D , Feigenbaum H , Godley R W , Weyman A E , Dillon J C , Phillips J F , Marshall J E
Published: June 2011

Advances in two-dimensional echocardiography have improved the prospects of using this technique to detect left main coronary artery (LMCA) obstruction. Using an echocardiograph that had digital gray scale, a 3-MHz transducer and strobe freeze-frame capability and reviewing recordings on an off-line videotape-videodisc analyzer, we retrospectively examined the LMCA in 72 patients who underwent coronary cineangiography. Angiography showed 50% or greater LMCA obstruction in seven patients. All seven had high-intensity echoes in the walls of the LMCA. The high-intensity echoes were irregularly located in the artery and partially occluded it. The LMCA could frequently be recorded proximal and distal to the obstruction. A blinded observer reviewed 28 randomly selected patients from this group and correctly identified the four patients with LMCA obstruction. There was one true and two questionable false-positive diagnoses. In a prospective study of 31 patients, two independent observers correctly identified the three patients with LMCA obstruction. There were no false negatives, and one observer had one false positive. All of the false positives were in patients with proximal left anterior descending coronary artery obstructions. Echocardiography may be a practical means of identifying patients with the LMCA obstruction.
Pneumonitis and pulmonary fibrosis associated with amiodarone treatment: a possible complication of a new antiarrhythmic drug.
Authors: Sobol S M , Rakita L
Published: June 2011

Six patients are presented who developed pulmonary infiltrates of undetermined origin while being treated for severe ventricular arrhythmias with amiodarone hydrochloride. Biopsy material was available in four patients and revealed interstitial or alveolar fibrosis and pneumonitis. Four patients recovered and two died of severe cardiopulmonary decompensation; all of the patients who recovered received corticosteroid therapy. Pulmonary fibrosis is a previously unreported complication of amiodarone therapy.
The differential diagnosis of acute pericarditis from the normal variant: new electrocardiographic criteria.
Authors: Ginzton L E , Laks M M
Published: June 2011

We examined the quantitative electrocardiographic differentiation of acute pericarditis from normal variant ST-T changes. The ECGs of 19 patients with acute pericarditis were compared with those of 20 subjects with typical normal variant changes. Patients were excluded if their ECGs demonstrated conditions that markedly altered repolarization. The positive predictive values (PPV) and negative predictive values (NPV) of previously reported criteria were not high (PPV = 0.54-0.83, NPV = 0.56-0.58). In contrast, in the present study, a T-wave amplitude in lead V6 of less than or equal to 0.3 mV diagnosed acute pericarditis (p less than 0.005, PPV = 0.85, NPV = 0.85), but there was overlap of patients between the groups. The ratio of the amplitude of the onset of the ST segment to the amplitude of the T wave in that lead (ST/T ratio in V6) proved to be the most reliable discriminator. An ST/T ratio greater than or equal to 0.25 diagnosed all patients with acute pericarditis (p less than or equal to 0.005, PPV = 1.0, NPV = 1.0). The ST/T ratio greater than 0.25 in V4, V5 (both p less than 0.005, PPV = 0.87, NPV = 1.0) and I (p less than or equal to 0.005, PPV = 0.80, NPV = 0.81) were also significant discriminators. Thus, if V6 is unavailable, an ST/T ratio greater than or equal to 0.24 in V5, V4 or I is highly suggestive of acute pericarditis. An ST/T ratio greater than or equal to 0.25 in V6 discriminated the ECGs of all patients with acute pericarditis from normal variants in this study.
Repair of aortico-left ventricular tunnel in the neonate: surgical, anatomic and echocardiographic considerations.
Authors: Turley K , Silverman N H , Teitel D , Mavroudis C , Snider R , Rudolph A
Published: June 2011

Repair of aortico--left ventricular tunnel was accomplished for the first time in the neonatal period. The diagnosis was made with two-dimensional echocardiography. Repair was accomplished using an open-patch aortoplasty technique, which prevented valvular insufficiency, a significant problem in older patients in whom the repair has been attempted.
Improvement of glucose tolerance and lowering of glycohemoglobin and serum lipid concentrations after discontinuation of antihypertensive drug therapy.
Authors: Ames R P , Hill P
Published: June 2011

Diuretic-based antihypertensive drug therapy causes a disturbance in glucose tolerance and in serum lipid and lipoprotein concentrations. To determine the reversibility of the glucose intolerance and to identify mechanisms of the metabolic alterations, we examined a short glucose tolerance test and insulin, glycohemoglobin and lipid concentrations during the supervised withdrawal of long-term drug therapy in 35 patients with primary hypertension. An average of 7 weeks after stopping drugs, glucose tolerance and glycohemoglobin improved, total cholesterol decreased 18 mg/dl, triglyceride decreased 27 mg/dl, and the ratio of total to high-density lipoprotein cholesterol decreased (p less than 0.01 for all variables vs treatment values). The changes in lipid concentrations from the treated to untreated state correlated with the changes in glycohemoglobin and indexes of glucose metabolism. The findings suggest that insulin resistance develops during drug therapy and disturbs both glucose and lipid metabolism. Attention to these alterations may provide directions for further control of atherosclerotic complications during the treatment of hypertension.
Subcostal two-dimensional echocardiographic imaging of peripheral right coronary artery in Kawasaki disease.
Authors: Yoshida H , Maeda T , Funabashi T , Nakaya S , Takabatake S , Taniguchi N
Published: June 2011

A new two-dimensional echocardiographic technique was developed to detect peripheral right coronary aneurysms in Kawasaki disease. Because the main stem of the right coronary artery runs along the tricuspid valve ring and the posterior interventricular groove, these regions were examined for coronary aneurysms using the subcostal approach. Of 52 patients with Kawasaki disease, 14 right coronary aneurysms were visualized in eight patients. Most of the coronary aneurysms were elicited as circular or oval echo-free spaces on the right side of the right ventricle or at the area around the tricuspid valve ring. These echocardiographic features coincided well in size, shape and anatomic position with angiographic appearances. The subcostal approach could not image the normal coronary artery. In three patients whose echocardiograms showed no abnormal echo-free space, the angiographic studies proved that the right coronary arteries were intact. These results suggest that this echocardiographic technique is useful for detecting peripheral right coronary aneurysms in patients with Kawasaki disease.
Effects of methylprednisolone on the ischemic damage in patients with acute myocardial infarction.
Authors: Madias J E , Hood W B
Published: June 2011

In this double-blind randomized study, 19 patients with acute transmural myocardial infarction were treated with methylprednisolone administered 4.4 +/- 0.7 hours (+/- SEM) after the onset of chest pain, and were compared with 21 patients who received placebo 4.5 +/- 0.4 hours after the start of clinical symptoms. The two groups were comparable in reference to sex, prevalence of risk factors, clinical status on admission, location of myocardial infarction and magnitude of ischemic injury as assessed by standard ECGs and precordial ST-segment and QRS maps. The treated patients, however, were older than the patients who received placebo. Methylprednisolone in an i.v. dose of 2.0 g was administered on admission and a similar dose was infused 3 hours later. Placebo administration followed an identical schedule. Mortality, cardiac rupture, incidence of ventricular arrhythmias, blocks, extension of myocardial infarction, pericarditis, postinfarction chest pain, persistent ST-segment elevation at discharge, and change in Killip class during hospitalization were the same in both groups. Peak enzyme values, and changes in ECG variables pertaining to resolution of ST-segment elevation or development of QRS evolutionary alterations were similar in both groups. Follow-up for 6 months did not reveal any differences in the clinical course of the two groups. Methylprednisolone infused in a total dose of 4.0 g within 12 hours after the onset of chest pain in patients with acute transmural myocardial infarction does not result in any demonstrable beneficial or harmful effects.
Effects of chronic hypertension and left ventricular hypertrophy on the incidence of sudden cardiac death after coronary artery occlusion in conscious dogs.
Authors: Koyanagi S , Eastham C , Marcus M L
Published: June 2011

When acute myocardial infarction occurs in patients with hypertension and left ventricular hypertrophy (LVH), the incidence of sudden cardiac death increases markedly. Possible explanations include increased size of the occluded vascular bed secondary to more extensive atherosclerotic coronary vascular disease in the presence of hypertension, decreased coronary reserve secondary to LVH, and intrinsic electrophysiologic abnormalities in hypertrophied cardiac muscle. To explore these possibilities, we produced acute circumflex coronary occlusion during the resting, conscious state in 32 control dogs and in 28 dogs with hypertensive LVH. Before coronary occlusion, mean arterial pressure was 96 +/- 0.1 mm Hg in control dogs and 125 +/- 5 mm Hg in dogs with hypertensive LVH (p less than 0.01). The control left ventricular/body weight ratio was 4.5 +/- 0.1 g/kg, compared with 6.1 +/- 0.1 g/kg in hypertensive LVH (p less than 0.01). Cumulative mortality at 6, 24 and 48 hours was 9%, 13% and 16% in control dogs and 32%, 43% and 54%, respectively, in dogs with hypertensive LVH (all p less than 0.01 vs control). The perfusion fields of the occluded vessel defined by postmortem coronary angiography were similar in the two groups (31 +/- 2% of left ventricular mass for control vs 29 +/- 2% for hypertensive LVH). Thus, the increased incidence of sudden cardiac death after coronary artery occlusion in hypertensive LVH dogs cannot be explained by increased size of the occluded vascular bed and is probably related to the decreased coronary reserve or intrinsic electrophysiologic abnormalities that characterize pressure-induced hypertrophied cardiac muscle.
Regional myocardial hemodynamic and metabolic effects of ionic and nonionic contrast media in normal and ischemic states.
Authors: Gerber K H , Higgins C B , Yuh Y S , Koziol J A
Published: June 2011

The effects of intracoronary injection of two nonionic contrast media (iohexol and metrizamide) on myocardial contraction and chemical composition of coronary sinus (CS) blood were compared with those caused by the standard ionic contrast material for coronary angiography, sodium meglumine diatrizoate (R76), in 14 anesthetized dogs. The effects of each agent on regional contractility were compared in the normal state and in the presence of a critical coronary artery stenosis. The three contrast media produced equivalent decreases in hematocrit and sodium (both NS), but R76 caused a greater increase in CS osmolality (p less than 0.02). R76 caused a significant decrease in CS potassium and ionized calcium (both p less than 0.001), but neither nonionic contrast medium caused a significant change in either potassium or calcium. In the normal state, R76 caused initial transient (less than 10 seconds) increases in both end-diastolic (p less than 0.006) and end-systolic segment length (p less than 0.02) and a decrease in rate of change of segment length (dL/dt) (p less than 0.002). The nonionic agents caused a mild increase in dL/dt (p less than 0.04) and a decrease in end-systolic segment length (p less than 0.03); both returned to control levels within 1 minute. In the presence of a stenosis, R76 caused a more severe and prolonged increase in end-diastolic and end-systolic segment lengths (p less than 0.03) and a decrease in dL/dt (p less than 0.002), which did not return to control within 2 minutes. The effects of the nonionic agents were similar in both normal and diseased states. We conclude that nonionic contrast media produce fewer alterations than ionic contrast media in coronary sinus blood chemistry and myocardial contractile state. The effect of ionic contrast media on regional contraction is accentuated in the presence of coronary artery stenosis.
Diastolic collapse of the right ventricle with cardiac tamponade: an echocardiographic study.
Authors: Armstrong W F , Schilt B F , Helper D J , Dillon J C , Feigenbaum H
Published: June 2011

The value of a newly described echocardiographic sign for the detection of cardiac tamponade was retrospectively evaluated in 91 patients. M-mode echocardiograms were reviewed in 86 patients, 36 of whom had concurrent two-dimensional echocardiographic examinations; in five patients, only two-dimensional echocardiography was performed. Cardiac tamponade was clinically present in 17 patients, 14 of whom had abnormal posterior motion of the right ventricular free wall in early diastole. Two of the 17 patients with tamponade had equivocally abnormal motion and one had normal wall motion. The patient with normal wall motion was later proved to have predominantly constrictive pericardial disease. In all cases, the abnormal wall motion reverted to normal after a definitive drainage procedure. Two-dimensional echocardiography confirmed that the abnormal right ventricular wall motion represented a true collapse of the right ventricular cavity in early diastole. Of the 69 patients without clinical cardiac tamponade, only seven had abnormal right ventricular wall motion. Detection of abnormal diastolic right ventricular free wall motion may be a sensitive indicator or a hemodynamically significant pericardial effusion. Conversely, the presence of normal motion of the right ventricular free wall appears to be a reliable indicator that the pericardial effusion is exerting little effect on overall cardiac function.
Identification of transient and persistent segmental wall motion abnormalities in patients with unstable angina by two-dimensional echocardiography.
Authors: Nixon J V , Brown C N , Smitherman T C
Published: June 2011

To determine the value of real-time, two-dimensional echocardiography (2-D echo) in unstable angina, regional wall motion on serial short-axis 2-D echo recordings was analyzed and summed segment scores of abnormal motion were compared and classified according to each patient's clinical status 12 weeks after hospital discharge. Nineteen male patients who fulfilled criteria for unstable angina and responded to medical therapy underwent 2-D echo study within 48 hours of admission and discharge. Of 11 patients with abnormal 2-D echo scores on admission, five patients had reduced scores and six patients had similar or increased scores at discharge. Six of eight patients who had scores of zero on admission had scores of zero at discharge. At follow-up, 11 patients had minimal or no angina pectoris (group 1), and eight patients had worsening angina or recurrent unstable angina (group 2). At discharge, 2-D echo studies showed that all group 1 patients had reduced or zero scores, while group 2 patients retained or increased their abnormal scores. This study shows that in patients with unstable angina, both transient and persistent abnormalities can be identified by 2-D echo. Abnormal segmental wall motion was transient or absent in patients with a good outcome, and worsened or remained abnormal in patients with a poor outcome.
Physiologic mechanisms in aortic insufficiency. I. The effect of changing heart rate on flow dynamics. II. Determinants of Austin Flint murmur.
Authors: Laniado S , Yellin E L , Yoran C , Strom J , Hori M , Gabbay S , Terdiman R , Frater R W
Published: June 2011

We studied the dynamic changes in mitral flow patterns and in mitral valve motion before and after producing acute, reversible aortic insufficiency (AI) in nine open-chest dogs. Phasic mitral flow, the mitral valve echocardiogram, and intracardiac phonocardiogram and other hemodynamic variables were measured. During moderate AI (mean regurgitant fraction 52 +/- 5%) (+/- SD), the antegrade filling volume decreased from 31 +/- 7 to 24 +/- 6 ml (p less than 0.01), but the peak protodiastolic mitral flow rate increased from 139 +/- 37 to 157 +/- 42 ml/sec (p less than 0.01), reflecting the shift of a larger fraction of total mitral filling volume to early diastole. In six dogs, atrial pacing was used to examine the hemodynamic effects of tachycardia. Increasing the heart rate from 90 to 120 beats/min increased cardiac output from 2.64 +/- 0.56 to 3.3 +/- 0.831/min (p less than 0.05) and decreased left atrial pressure from 24 +/- 8 to 17 +/- 7 mm Hg (p less than 0.05). Increasing heart rate to 150 beats/min compromised mitral filling, reduced cardiac output and increased left atrial pressure. Moderate tachycardia improves cardiac performance in AI by reducing regurgitant volume, without significantly reducing transmitral filling volume. The mitral valve echocardiogram showed only a small decrease in cusp opening amplitude during AI. A low-pitched left ventricular inflow tract murmur was recorded in protodiastole and corresponded in time to the rapidly increasing mitral flow. We conclude that the major determinant of the turbulence responsible for the creation of the austin flint murmur is the antegrade mitral flow stream and its mixing with the retrograde aortic flow.
Neuronal and adrenomedullary catecholamine release in response to cardiopulmonary bypass in man.
Authors: Reves J G , Karp R B , Buttner E E , Tosone S , Smith L R , Samuelson P N , Kreusch G R , Oparil S
Published: June 2011

Cardiopulmonary bypass (CPB) alters systemic hemodynamics and affects several biochemical systems involved in cardiovascular regulation. We investigated the changes in levels of circulating epinephrine (E) and norepinephrine (NE) and related them to events during CPB. Twenty-eight patients undergoing various surgical procedures were studied. Plasma E and NE were determined by radioenzymatic assay at eight stages of the operation. A ninefold increase in arterial E (from 75 +/- 13 to 708 +/- 117.3 pg/ml) occurred from prebypass (stage 1) measurements to the end of aortic cross-clamping (stage 4). The values at stage 4 were significantly higher (p less than 0.05) than at all other stages. E decreased rapidly, to 360 +/- 84.3 pg/ml, after myocardial and pulmonary reperfusion (stage 5). Arterial NE increased twofold from stage 1 to stage 4 (from 426 +/- 66.9 to 825 +/- 84.2, p less than 0.05). The increase in NE from initial CPB values (stage 2) to 30 minutes of aortic cross-clamping (stage 3) was associated with an increase in mean blood pressure (r = 0.51, p = 0.02). The peak increases in catecholamines occurred when the heart and lungs were excluded from the circulation, which suggests that either or both contributed to the increase. Because the increase in E was markedly greater than that in NE, the predominant humoral response to CPB appears to be adrenomedullary release of E. This significant increase in catecholamines could jeopardize myocardial protective measures during CPB.
Does dietary health education reach only the privileged? The Stanford Three Community Study.
Authors: Fortmann S P , Williams P T , Hulley S B , Maccoby N , Farquhar J W
Published: June 2011

The relationship of selected social factors to diet, weight and plasma cholesterol was studied in one control and two treatment towns before and after a 3-year, bilingual, mass-media health education program. Spanish-speaking persons reported higher dietary cholesterol and saturated fat than English-speaking participants at baseline, and this remained true after adjusting for the confounding influence of socioeconomic status (SES). Obesity was also more prevalent in Spanish-language and low-SES groups, but plasma cholesterol was not related to these sociodemographic factors. Over the 3 years of the education program, all groups reported 20-40% decreases in dietary cholesterol and saturated fat. These decreases were as large in low-SES groups as in high-SES groups; Spanish-speaking participants reported significantly greater decreases in dietary saturated fat (p = 0.02). Weight change was not related to either SES or language group, but change in plasma cholesterol was marginally more favorable in Spanish-speaking subjects (p = 0.06).
Coronary collateral function during exercise.
Authors: Eng C , Patterson R E , Horowitz S F , Halgash D A , Pichard A D , Midwall J , Herman M V , Gorlin R
Published: June 2011

A totally occluded coronary vessel subtending a noninfarcted, entirely collateral-dependent myocardial region (NIECDMR) provides an opportunity to assess collateral perfusion during exercise stress. Collateral function was determined by analysis of exercise thallium-201 myocardial perfusion images from 31 patients who had at least one NIECDMR (total 41 NIECDMRs) documented during catheterization. Twenty-two of 41 NIECDMRs manifested exercise-induced perfusion defects and 19 were normally perfused. The exercise-negative NIECDMRs were further categorized: Group 1 NIECDMRs (n = 13) were associated with defects in other myocardial regions supplied by diseased vessels and were considered negative relative to other jeopardized regions; group 2 NIECDMRs (n = 6) were not associated with exercise-induced defects in other myocardial regions, which suggests that collateral perfusion was adequate during maximal exercise. Regions supplied by a diseased left anterior descending coronary artery manifested exercise defects regardless of collaterals, possibly because these regions were larger and required more perfusion. Angiographic indexes of collateral function did not clearly predict exercise results.
Significance of the angiographic morphology of localized coronary stenoses: histopathologic correlations.
Authors: Levin D C , Fallon J T
Published: June 2011

Postmortem coronary angiographic morphology was correlated with histologic sections of 73 localized subtotal coronary artery stenoses (50-99% reduction of luminal diameter) to determine whether complicated or uncomplicated atherosclerotic lesions could be detected angiographically. Lesions were divided into two types, according to angiographic morphology: Type I stenoses had smooth borders, an hourglass configurations, and no intraluminal lucencies; type II stenoses had irregular borders or intraluminal lucencies. Histologic sections were also divided into two types: "uncomplicated" stenoses had fatty or fibrous plaques with intact intimal surfaces and no superimposed thrombus; "complicated" stenoses manifested plaque rupture, plaque hemorrhage, superimposed partially occluding thrombus, or recanalized thrombus. Among 35 lesions with type I angiographic morphology, four (11.4%) were complicated lesions histologically. Among the 38 stenoses showing type II angiographic morphology, 30 (78.9%) were complicated lesions. Postmortem angiography thus had a sensitivity of 88% and specificity of 79% for detecting complicated stenoses on the basis of irregular borders or intraluminal lucencies. Pathologic studies have shown that acute occlusive thrombosis of a coronary artery is usually associated with complicated atherosclerotic stenoses. Thus, complicated lesions represent a greater risk factor for acute myocardial infarction or sudden death than do uncomplicated lesions. This study suggests that coronary stenoses characterized angiographically by irregular borders or intraluminal lucencies are probably the clinically more dangerous "complicated" type.
The cardiac effects of d- and l-disopyramide in normal subjects: a noninvasive study.
Authors: Pollick C , Giacomini K M , Blaschke T F , Nelson W L , Turner-Tamiyasu K , Briskin V , Popp R L
Published: June 2011

Commercially available disopyramide is a racemic mixture of equal parts of dextrorotatory (d-) and levorotatory (l-) optical isomers. We studied the cardiac effects of i.v. administration of each isomer and the racemic mixture (dl-) in six normal males by digitized echocardiography, systolic time intervals and ECG. Both isomers and the racemic mixture produced equally marked dose-dependent negative inotropic effects (28.1 +/- 11.8% mean maximal reduction in fractional shortening of left ventricular dimension) and diastolic effects (28.6 +/- 24.1% mean maximal reduction in peak left ventricular filling rate). However, only the d-isomer prolonged QTc duration (by 13.6 +/- 5.2% at maximum, p less than 0.001 vs l-isomer). We conclude that disopyramide, in the doses used, produces marked adverse effects on left ventricle systolic and diastolic function in normal subjects independent of optical rotation. The production of these effects by the l-isomer without affecting QTc duration suggests different subcellular mechanisms for the myocardial depressant effects and some of the electrophysiologic effects of disopyramide.
Effects of physical training on myocardial vascularity and perfusion.
Authors: Scheuer J
Published: June 2011

Physical training is thought to be a stimulus for coronary vascular growth and coronary collateral development. This report is a summary of knowledge in the area. Studies in experimental animals with normal hearts indicate that physical training promotes increased myocardial capillary density and also causes enlargement of the surface coronary vessels. The physiologic effect of these changes on coronary vascular reserve and protection of segments of the heart against myocardial ischemia has not been established. Physically trained dogs and pigs do not appear to be protected against the effects of coronary occlusion, in that the ischemic area appears to be as large in trained animals as in untrained animals for any given coronary lesion. One study in physically trained rats appears to show protection against myocardial infarction, but whether this is related to coronary vascular changes has not been established. Experiments in dogs subjected to chronic narrowing or gradual occlusion demonstrate that physical training in these models does promote collateral blood flow as measured by retrograde flow in open-chest experiments. Studies using the microsphere technique in closed-chest animals confirms increased collateral flow to ischemic areas in some animals, but the magnitude of the increases appears to be small and varies greatly from animal to animal. Studies in athletes suggest that myocardial blood flow is lower at any submaximal level of training in athletes than in sedentary persons. Studies in patients with coronary artery disease have generally failed to show an increase in coronary blood flow or in perfusion of ischemic areas after physical training programs, but the techniques used might not have been sensitive enough to detect changes. The evidence in the experimental animals is sufficiently promising to indicate that the search should be continued to define physical training programs that will most stimulate myocardial vascularity and coronary collaterals in humans.
The effect of intraaortic balloon counterpulsation on regional myocardial blood flow and oxygen consumption in the presence of coronary artery stenosis in patients with unstable angina.
Authors: Williams D O , Korr K S , Gewirtz H , Most A S
Published: June 2011

To determine whether a reduction in myocardial oxygen demand or an increase in coronary blood flow or both are responsible for the salutory effect of intraaortic balloon counterpulsation (IABP) in relieving medically refractory angina, we assessed these variables in six patients in whom IABP was required for relief of myocardial ischemia. IABP decreased the rate-pressure product and aortic end-diastolic pressure, and the peak systolic aortic pressure and regional myocardial oxygen consumption declined in all but one patient. Peak and mean aortic diastolic pressures increased. Changes in regional coronary blood flow paralleled changes in peak systolic aortic pressure (r = 0.92, p less than 0.007). Thus, relief of angina during IABP could not be ascribed to an increase in regional coronary blood flow. Reduction of myocardial oxygen consumption is the most likely mechanism by which IABP relieves myocardial ischemia in patients with unstable angina pectoris.
Two-dimensional echocardiography in experimental coronary stenosis. II. Relationship between systolic wall thinning and regional myocardial perfusion in severe coronary stenosis.
Authors: Pandian N G , Kieso R A , Kerber R E
Published: June 2011

To determine if there is a quantitative relationship between systolic contraction abnormalities (demonstrated by two-dimensional echocardiography) and reduced myocardial perfusion in a setting of moderate and severe coronary stenosis, we created 70% or 90% reduction in circumflex coronary artery diameter in open-chest dogs. Transient ischemia was induced by superimposing increased myocardial oxygen requirements (i.v. isoproterenol, aortic constriction) in the presence of the stenosis or by decreased coronary perfusion (lowering arterial pressure with i.v. nitroprusside, nitroglycerin, or hemorrhage). Acute systolic wall thinning show by two-dimensional echocardiography or by implanted myocardial sonomicrometers was taken as functional evidence of myocardial ischemia. Myocardial perfusion was determined by radiolabeled microspheres when wall thinning was apparent. Systolic wall thinning could not be induced by these interventions when the degree of coronary stenosis was only 70%. Systolic wall thinning occurred only when increased myocardial oxygen requirements or decreased aortic pressure were superimposed on 90% coronary stenosis. Under these conditions, myocardial perfusion was reduced to 28 +/- 27 ml/100 g/min (mean +/- SD), 15--25% of control. Aortic diastolic pressure was a major determinant of ischemia in that contraction abnormalities produced by a 90% stenosis and vasodilators or hemorrhage could be acutely reversed by superimposing acute aortic constriction, which elevated arterial pressure; myocardial perfusion increased correspondingly. Thus, the demonstration of transient systolic wall thinning by two-dimensional echocardiography during a stressful intervention indicated that severe coronary stenosis was present, and that the perfusion of the acutely dyskinetic myocardial area was 25% of control or less.
Serial thallium-201 myocardial imaging after dipyridamole infusion: diagnostic utility in detecting coronary stenoses and relationship to regional wall motion.
Authors: Leppo J , Boucher C A , Okada R D , Newell J B , Strauss H W , Pohost G M
Published: June 2011

After a 4-minute i.v. dipyridamole infusion, 0.14 mg/kg/min, serial thallium-201 scans were obtained in 60 patients undergoing cardiac catheterization. Forty patients had significant (greater than or equal to 50% stenosis) coronary artery disease (CAD), and 20 patients had normal coronary arteries or trivial lesions. The images were graded qualitatively for thallium activity by three observers. Sensitivity was 93% (37 of 40) and specificity was 80% (16 of 20). The sensitivity and specificity of the thallium-201 study were not affected by the extent of CAD, the presence of Q waves, or propranolol therapy. Twenty-seven of 37 patients who had initial defects (73%) had complete thallium redistribution of one or more defects. Patient-by-patient analysis using a regression model of all patients showed that the fate of a segmental thallium defect predicted abnormal wall motion by angiography better than ECG Q waves. The presence of propranolol therapy or collaterals did not significantly affect the thallium redistribution results. We conclude that qualitative interpretation by multiple observers of thallium images after dipyridamole infusion is a highly sensitive and specific test for CAD. After dipyridamole, as with exercise stress, the extent of thallium redistribution is related to the degree of myocardial wall motion abnormality.
Hemodynamic differences between supine and upright exercise in patients with congestive heart failure.
Authors: Kramer B , Massie B , Topic N
Published: June 2011

Although the differences in hemodynamic responses to supine and upright exercise have been studied in normal subjects and in patients with angina pectoris, no such comparison has been made in patients with congestive heart failure. Many investigators measure exercise hemodynamics in heart failure patients to assess the effect of vasodilator and inotropic drugs. Both modes of exercise have been used and have often yielded differing results. We compared the hemodynamic response to supine and upright exercise in 14 patients with stable, New York Heart Association class III chronic heart failure. During upright exercise, peak heart rate was higher (124 +/- 15 vs 115 +/- 18 beats/min, p less than 0.025) and peak mean arterial pressure was lower (102 +/- 15 vs 95 +/- 17 mm Hg, p less than 0.25), yielding similar double products. Although the peak left ventricular filling pressure was slightly lower during upright exercise (40 +/- 7 vs 35 +/- 10 mm Hg, p less than 0.05), the maximum cardiac and stroke indexes were not significantly different (3.6 +/- 0.8 vs 3.4 +/- 0.8 l/min/m2 and 30 +/- 8 vs 30 +/- 6 ml/m2, upright vs supine exercise). In contrast to these relatively similar hemodynamic responses, exercise capacity was significantly greater during upright exercise (peak work load 336 +/- 84 vs 293 +/- 73 kpm/min, p less than 0.1; maximum oxygen consumption 12.1 +/- 2.4 vs 9.8 +/- 1.9 ml/min/kg, p less than 0.001). We conclude that either exercise method may be used to assess the hemodynamic effects of drugs, but that exercise capacity should be measured in the upright position.