bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparative responses to dobutamine and nitroprusside in patients with chronic low output cardiac failure.
Authors: Berkowitz C , McKeever L , Croke R P , Jacobs W R , Loeb H S , Gunnar R M
Published: June 2012

The acute hemodynamic effects of dobutamine and nitroprusside were compared in 19 patients with low output cardiac failure. At dosage levels yielding similar increases in cardiac index (12 patients), nitroprusside resulted in significantly lower arterial systolic and wedge pressures and did not increase heart rate suggesting advantages over dobutamine when reduction in myocardial oxygen requirement or pulmonary congestion is a major goal. Systemic arterial mean and diastolic pressures were minimally changed with dobutamine, but fell significantly with nitroprusside suggesting advantages of dobutamine over nitroprusside in patients where hypotension could limit coronary blood flow or perfusion of other vital organs. Reduction in pulmonary arteriolar resistance occurred only with nitroprusside. Arterial hypoxemia developed in three patients during nitroprusside infusion suggesting the possibility of increased right-to-left intrapulmonary shunting resulting from a direct vasodilating effect of nitroprusside on pulmonary arteriole smooth muscle. Although both inotropic and vasodilator drugs can result in hemodynamic improvement when administered to patients with chronic low output cardiac failure, significant differences of potential clinical importance exist between these two modes of therapy.
The influence of constitutional variables on orthogonal electrocardiograms of normal women.
Authors: Nemati M , McCaughan D , Doyle J T , Pipberger H V
Published: June 2012

Correlations between 276 orthogonal electrocardiographic measurements and constitutional variables were made in 450 normal women, aged 18 to 90 years. Advancing age led to decreases in amplitudes, left QRS axis shift, rightward and superior displacement of the ST segment, and anterior shift of the T wave. QZ was absent in 1% of normal women over age 40. In the oldest subjects, Ry amplitude was 71% and RZ amplitude was 80% of the respective values in the youngest group. Whereas QRS amplitude decreases with age leveled off at the sixth decade of life, they continued to old age for ST-T measurements. Men revealed steeper age trends than women. Blacks had larger QRS amplitudes and smaller Q/R ratios than whites. Stratification of electrocardiographic criteria according to age, sex, and race appears essential for routine interpretations and for epidemiological studies where new events, such as myocardial infarcts, need to be differentiated from normal age trends.
Atrial pacing from the coronary vein. Ten-year experience in 50 patients with implanted pervenous pacemakers.
Authors: Moss A J , Rivers R J
Published: June 2012

During the past ten years, pervenous atrial pacemakers have been implanted in 50 patients (mean age 68 years, 60% males) using an electrode positioned in the coronary vein. The indications for atrial pacing were symptomatic sinus bradycardia (72%), atrial brady-tachy syndrome (20%), and recurrent tachyarrhythmias (8%). Atrial pacemakers have been implanted for a total of 1531 pacing months, average 31 months per patient, median 26 months and range 3-97 months. Effective atrial pacing has been achieved with Medtronic model 5818 and 6904 electrodes. Unipolar or bipolar atrial pacing has been equally effective, and commercially available Medtronic 5950, Cordis 162 and CPI 602 pulse generators have been utilized without difficulty. A total of 11 electrode related malpacing events occurred in the ten-year period with a malpacing event rate of 10% in the first pacing month, 1.1% per paced month during the next six months, and 0.25% per paced month thereafter. Life table analysis reveals that effective atrial pacing was achieved in 76% of the patients during a follow-up of more than five years. This experience substantiates the long-term safety and effectiveness of atrial pacing from the coronary vein using standard pacemaker electrodes and generators.
Diffuse coronary artery disease in diabetic patients: fact or fiction?
Authors: Dortimer A C , Shenoy P N , Shiroff R A , Leaman D M , Babb J D , Liedtke A J , Zelis R
Published: June 2012

To compare angiographically-determined coronary artery disease in diabetic patients with controls, 1,653 patients coming to cardiac catheterization were reviewed retrospectively to find 37 diabetic and 79 control patients matched for sex, age (+/- 3 years), and risk factors (hypertension, hyperlipidemia, and smoking). The severity of coronary artery disease was assessed using an angiographic grading system. The following results were obtained: 16 of 37 diabetic patients (43%) had three-vessel disease compared to 20 of 79 controls (25%). Seventy-six of 111 (68%) diabetic vessels were diseased compared to 110 of 237 control vessels (46%) (P less than 0.005). The total coronary score reflecting total extent of disease for diabetic patients was 371 (mean 10.0 +/- (SEM) compared to 594 for controls (mean 7.5 +/- 0.7, (P less than 0.01). Diabetic patients had a statistically similar number of diffusely diseased vessels as controls (28% vs 22%). There were only three of 76 diabetic vessels (4%) considered inoperable compared to seven of 110 (6%) control vessels. We conclude that diabetic patients with chest pain have more coronary artery disease than nondiabetics, but no more diffuse or inoperable disease.
Nifedipine therapy for Prinzmetal's angina.
Authors: Muller J E , Gunther S J
Published: June 2012

A case is described in which nifedipine, a new coronary vasodilator, was effective in relieving attacks of Prinzmetal's angina unresponsive to conventional therapy. The extreme frequency of the anginal attacks provided evidence that lower doses of nifedipine lost their effectiveness approximately 4 hours after administration. A month after initiation of nifedipine, nitrates were withdrawn since they had been ineffective in controlling the attacks. A myocardial infarction occurred immediately, presumably due to coronary spasm.
Active valvulitis associated with chronic rheumatic valvular disease and active myocarditis.
Authors: Edwards W D , Peterson K , Edwards J E
Published: June 2012

From ten patients aged 15 to 40 years with chronic rheumatic valvular disease and histologically proved Aschoff bodies of active rheumatic myocarditis, the valves were evaluated for incidence, distribution and degree of severity of active inflammation. Prior to death, there had been clinical evidence of active rheumatic fever. In each case, active rheumatic valvulitis was present in at least one valve. Of the individual valves studied, 83% were involved by active inflammation of the leaflets or the anulus or both. The aortic valves was involved in 100% of cases, the mitral valve in 86%, the tricuspid valve in 78% and the pulmonary valve in 70%. The mitral and aortic valves were most frequently involved, but the mitral and tricuspid valves were most severely involved when affected. In every case, active rheumatic lesions of the left atrial appendage were present, but these tended to be less widely distributed than the myocardial Aschoff bodies. The high incidence of active valvulitis supports the concept that chronic fibrosing rheumatic valvular disease results from recurrent active inflammation. Such inflammation may occur without clinical suspicion of active rheumatic fever.
Migratory traumatic cardiovascular foreign bodies.
Authors: Moncada R , Matuga T , Unger E , Freeark R , Pizarro A
Published: June 2012

Six cases of cardiovascular foreign bodies secondary to trauma are presented. The various modes of entry and travel within the vascular are reviewed. Routine radiographic examination and angiography are shown to be the most useful techniques in defining the location and subsequent course of the foreign body in the vascular system.
Cryoablation of drug-resistant ventricular tachycardia in a patient with a variant of scleroderma.
Authors: Gallagher J J , Anderson R W , Kasell J , Rice J R , Pritchett E L , Gault H J , Harrison L , Wallace A G
Published: June 2012

A 37-year-old man with a benign variant of scleroderma (CRST syndrome: calcinosis circumscripta, Raynaud's phenomenon, sclerodactyly, and telangiectasia) presented with recurrent ventricular tachycardia. Preoperative electrophysiologic study suggested that the mechanism of tachycardia was an ectopic pacemaker focus in the right ventricle. Right ventricular dilatation, tricuspid insufficiency, normal pulmonary pressures, and normal coronary arteries were also demonstrated. At surgery, epicardial mapping localized the site of origin of ventricular tachycardia to the anterior right ventricle near the crista supraventricular. Intramural recordings of the site of tachycardia demonstrated autonomous activity unreflected on the peripheral ECG during brief periods of sinus rhythm. Local epicardial cooling of this area with a cryoprobe promptly terminated ventricular tachycardia with resumption of tachycardia on warming. The focus was ablated by freezing the area at -60 degrees C. The patient remained free of dysrhythmia on no anti-arrhythmic agents for eight months at which time he had a single recurrence of ventricular tachycardia from a different site in the right ventricle. This technique offers a method for ablating sites of dysrhythmia arising in diffusely diseased myocardium.
Spontaneous near closure of coronary artery fistula.
Authors: Shubrooks S J , Naggar C Z
Published: June 2012

An asymptomatic 14-year-old male was found at cardiac catheterization to have a coronary artery fistula involving a vessel originating from the left main coronary artery and terminating in the right heart. Chest X-ray and electrocardiogram were within normal limits and shunt flow was too small to be detected by oximetry although a large vessel was seen angiographically. One year later, the previously loud continuous murmur had disappeared and repeat catheterization demonstrated near closure of the fistula. This is the first report documenting the spontaneous closure of a coronary artery fistula.
Evaluation of methods for the quantification of experimental myocardial infarction.
Authors: Roberts A J , Cipriano P R , Alonso D R , Jacbostein J G , Combes J R , Gay W A
Published: June 2012

Several invasive and noninvasive techniques used in determining the size of experimental myocardial infarction were evaluated after acute ligation of the left anterior descending (LAD) coronary artery in ten dogs. Systemic blood pressure, left ventricular end-diastolic pressure (LVEDP), and heart rate did not change significantly for up to 24 hours after coronary occlusion. Left ventricular wall motion abnormalities were detected by left ventriculography in the distribution of the LAD but these changes did not correlate well with the infarct weight determined at autopsy. On the other hand, the number of epicardial sites with ST-segment elevation of greater than or equal to 2 mm (mean 15.1 sites +/- 0.6 SEM) and the infarct area as measured by 99mTc-glucoheptonate (TcGH) myocardial imaging (15.7 sq cm +/- 0.6) did correlate strongly with the infarct weight (16.8 g +/- 0.7) determined by the nitroblue tetrazolium (NBT) technique (r = 0.91). TcGH myocardial scintigraphy and epicardial ST-segment mapping allowed early and accurate quantification of experimental myocardial infarcts ranging from less than 1 g to 28 g.
Effects of pharmacologically-induced hypertension on myocardial ischemia and coronary hemodynamics in patients with fixed coronary obstruction.
Authors: Loeb H S , Saudye A , Croke R P , Talano J V , Klodnycky M L , Gunnar R M
Published: June 2012

Twenty patients with fixed coronary artery obstruction were studied during rapid atrial pacing and methoxamine infusion. During pacing to heart rates of 142 +/- 4 (mean +/- SEM) beats per minute coronary sinus flow increased from 108 +/- 8 to 187 +/- 15 cc/min and myocardial oxygen consumption increased by + 80 +/- 11%. During methoxamine infusion that raised arterial systolic pressure to 196 +/- 5 mm Hg, similar increases in coronary sinus flow (to 179 +/- 13 cc/min) and myocardial oxygen consumption (+ 77 +/- 12%) occurred. Chest pain and ischemic ST segment changes developed in 17 and 14 patients respectively during atrial pacing, an incidence significantly greater (P less than 0.05) than during infusion of methoxamine (6 and 3 patients). Myocardial lactate extraction which averaged 26 +/- 4% during control was decreased to 10 +/- 8% during pacing and to 24 +/- 7% during methoxamine; the difference between decreases was not significant. The data show that at similar increases in myocardial oxygen consumption stress of increased heart rate results in more myocardial ischemia than stress of increased afterload.
Improved efficiency of treadmill exercise testing using a multiple lead ECG system and basic hemodynamic exercise response.
Authors: Chaitman B R , Bourassa M G , Wagniart P , Corbara F , Ferguson R J
Published: June 2012

One hundred consecutive men with a normal ECG at rest had a maximal treadmill test using 14 leads during and post-exercise. Coronary arteriography performed the following day revealed coronary stenoses greater than or equal to 70% in 66 patients. Test results obtained from a V5 lead were compared to different lead combinations and were correlated with arteriographic findings. A positive exercise test occurred in 37 men using an isolated V5 lead compared to 50 men (P less than 0.05) using 11 leads, 52 men (P less than 0.05) using a combined CM5, CC5, Cl (inferior) lead system and 58 (P less than 0.001) men using all 14 leads. The predictive value of a positive test varied between 89-95% and was not changed significantly by the addition of multiple leads. The 14 lead ECG was positive in 43/45 (96%) patients with multivessel disease. Parameters which helped to predict multivessel disease using 14 leads were 1) the time that ischemia first appeared 2) the pressure-rate product at the time ischemia first appeared, and 3) the maximum workload that could be attained. In general, the magnitude of ST-segment depression and the time required for a positive ECG to return to normal postexercise were not useful predictors of multivessel disease. We conclude that the use of multiple leads improves the sensitivity and efficiency of the maximal treadmill exercise test. The usefulness of exercise test results can be further improved if multiple leads are combined with physiologic data collected during exercise.
Maximal heart rate and treadmill performance of healthy women in relation to age.
Authors: Sheffield L T , Maloof J A , Sawyer J A , Roitman D
Published: June 2012

Maximal treadmill exercise heart rate, work capacity and electrocardiographic response were studied in 95 asymptomatic, predominantly sedentary women between the ages of 19 and 69 years. Average maximal heart rate (MHR) was found inversely related to age, such that MHR = 216 -0.88 (years of age) +/- 10 beats/min (X +/- 1 SD). Treadmill exercise endurance was 7.64 min +/- 1.99. The reduction of treadmill endurance with advancing age was not statistically significant. Asymptomatic ST-segment depression occurred in 6% of subjects. In 5% the ST segment sloped upward, and in 1% it was flat. Mean age of women with ST depression was 52 years, compared with 39 years mean age of all subjects. Premature beats during exercise were found in 20 of 95 subjects, and were not related to age. Graded exercise testing of women employing target heart rates should use heart rate tablets developed especially for women. These tables do not require correction for athletically trained for sedentary life-style.
Coronary sinus pacing clinical follow-up.
Authors: Greenberg P , Castellanet M , Messenger J , Ellestad M H
Published: June 2012

Coronary sinus pacing is a safe and effective means of pacing from the atrium. In 66 patients with an average follow-up of 14 months, there was a 14% failure rate. There were transient problems in 14% which were subsequently corrected. There was a 6% death rate which was not pacemaker related. Successful atrial pacing with thresholds up to 6.0 mA is feasible. Atrial pacing was successful in 18 of 19 patients with varying degrees of atrioventricular block. Our experience with a new electrode has been very satisfactory.
Detection of myocardial scar tissue by M-mode echocardiography.
Authors: Rasmussen S , Corya B C , Feigenbaum H , Knoebel S B
Published: June 2012

Wall thicknesses were measured and echo densities were evaluated from the left ventricular echograms of 182 patients. The echogram was considered to reflect scar tissue when 1) either the interventricular septum, the posterior left ventricular wall or the anterior left ventricular wall was less than 7 mm thick in mid-diastole and was more echo-producing than its opposing wall or another area of the same wall in a sector scan, or 2) an area of myocardium was 30% less thick than an adjacent area within a sector scan. Myocardial scarring was diagnosed by echocardiography in 52 of the 182 patients. The echocardiographic presence or absence of scarring was confirmed in 95% (173 of 182) of cases, 34 cases by microscopic examination and 139 by surgical appearance. This study shows that M-mode echocardiography is both a sensitive and specfic method for detecting myocardial scar tissue.
Aortic stenosis in children. Experience with echocardiographic prediction of severity.
Authors: Blackwood R A , Bloom K R , Williams C M
Published: June 2012

Fifty-six children with aortic stenosis were investigated both by echocardiography and cardiac catheterization. The ratio of end-systolic wall thickness (Ws) to internal diameter (LVES) across the minor axis of the LV as determined by echocardiography and multiplied by a factor of 245 predicts left ventricular pressure (r = 0.83). Subtracting the arm systolic blood pressure from the predicted intraventricular systolic pressure (PISP) gives a predicted systolic pressure gradient (r = 0.91). The technique is found to be useful for both initial and sequential noninvasive assessment of aortic stenosis with normal LV function irrespective of the level of obstruction. It is shown to apply equally well to wide range of LV pressures, is independent of volume load, and is useful in predicting small gradients. Some common problems encountered with the measurements are examined in detail.
The reliability and practicality of single crystal echocardiography in the evaluation of single ventricle. Angiographic and pathological correlates.
Authors: Bini R M , Bloom K R , Culham J A , Freedom R M , Williams C M , Rowe R D
Published: June 2012

A prospective clinical and echocardiographic diagnosis of single ventricle was made in 42 patients. Each was evaluated for the number of atrioventricular (A/V) valves, presence of an outflow chamber (OC), A/V valve-semilunar continuity, and orientation of the great arteries. Angiographic correlations were subsequently obtained in 40 and autopsies in 12. The overall diagnosis of single ventricle was substantiated in 39. Two other patients diagnosed as single ventricle by angiography were thought to have large ventricular septal defects on echocardiography. Tricuspid valve was interpreted as septum in one. The angiographic diagnosis of single ventricle was incorrect in another, correctly diagnosed by echocardiography and confirmed at pathology. The differential diagnosis also included A-V canal, L-transposition of the great arteries, double outlet right ventricle, and tricuspid atresia. This last condition has to be differentiated on clinical evidence. The echocardiograms were of particular value in determining the number of A/V valves. Two great arteries were demonstrated in 74% of patients and their relationship was correctly determined in 79% of these. Both imaging techniques agreed closely as to A/V valve-semilunar continuity and presence of an OC, but both showed some inaccuracies compared to pathological specimens. The echocardiogram helps both in planning catheterization and in evaluating the overall diagnosis.
Echocardiographic measurements in normal subjects. Growth-related changes that occur between infancy and early adulthood.
Authors: Henry W L , Ware J , Gardin J M , Hepner S I , McKay J , Weiner M
Published: June 2012

Echocardiographic measurements of the left ventricular dimensions and wall thicknesses at end diastole and end systole, aortic root and left atrial dimensions, mitral valve E-F slope, left ventricular ejection fraction, percent fractional shortening of the left ventricular internal dimension, estimated left ventricular mass and percentage systolic thickening of the ventricular septum and left ventricular free wall were obtained in 105 normal subjects ranging from one day to 23 years of age. Each parameter was found to follow a linear regression upon one of three functions of the body surface area. The internal dimensions of left ventricle, the left atrium, and the aortic root, and the mitral valve E-F slope varied in a linear relation to the cube root of the body surface area. Thickness of the ventricular septum and left ventricular free wall varied in a linear relation to the square root of the body surface area. Estimated left ventricular mass varied linearly with the direct measurement of body surface area. Ejection fraction, percent fractional shortening of the left ventricle and percent systolic thickening of the ventricular septum and left ventricular free wall were independent of body surface area despite a marked increase in the size of the left ventricle during normal growth and development.
Echocardiographic and hemodynamic correlation in transposition of the great arteries.
Authors: Park S C , Neches W H , Zuberbuhler J R , Mathews R A , Lenox C C , Fricker F J
Published: June 2012

Echocardiography was performed in 36 patients with transposition of the great arteries (TGA). Twenty patients were studied before a Mustard operation, 14 patients after operation and two patients both before and after operation. Right ventricular end-diastolic dimension (RVED) was larger than normal in each patient and tended to increase postoperatively. In contrast, the left ventricular end-diastolic dimension (LVED) was significantly reduced postoperatively in all patients. A linear relationship was demonstrated between the ratio of LVED/RVED and the ratio of peak systolic pressures in the left and right ventricles in studies both before and after Mustard operation. Systolic anterior motion of the mitral valve was observed in 18% of peroperative patients and increased to 44% postoperatively. The incidence of fluttering of the mitral valve increased from 50% to 94% after the operation. Abnormal septal motion was found in 39% of cases. Abnormal movement of the mitral valve and of the interventricular septum seems to be related to a reversed pressure relationship in the ventricles. Shifting of the ventricular septum toward the left ventricle and consequent distortion of the left ventricular cavity and mitral valve apparatus may be responsible for the abnormal echocardiographic findings. Serial echocardiographic studies may be useful as a noninvasive tool in the assessment of left ventricular pressure or the status of the pulmonary vascular bed in TGA.
The clinical estimation of acute myocardial infarct size with 99mTechnetium pyrophosphate scintigraphy.
Authors: Sharpe D N , Botvinick E H , Shames D M , Norman A , Chatterjee K , Parmley W W
Published: June 2012

We evaluated scintigraphic techniques in estimating infarct size. In 26 patients with acute transmural myocardial infarction, 99mTechnetium pyrophosphate (TcPYP) infarct scintigraphy, gated cardiac blood pool scintigraphy and 201-Thallium (201-Tl) perfusion scintigraphy were performed. Invasive hemodynamic measurements were obtained and serial venous blood specimens taken for measurement of total and MB creatine phosphokinase (CPK). In farct size was estimated from the area of abnormal TcPYP uptake, the extent of reduced 201-Tl uptake, the percentage of abnormally contracting segments, and serial enzyme measurements. Left ventricular ejection fraction (LVEF) and stroke work index (LVSWI) were calculated. TcPYP infarct area was associated with the extent of reduced 201-Tl uptake (r = 0.66), the percentage of abnormally contracting segments (r = 0.64), and with both LVSWI (r = 0.73) and LVEF (r = 0.58). TcPYP infarct area did not correlate with cumulative total or MB-CPK release or the integrated total CPK-time curve, nor did the enzyme estimates of infarct size correlate with LVSWI or LVEF. Variable perfusion of infarcts of different sizes may explain the lack of correlation between TcPYP infarct area and enzyme estimates of infarct size. A combination of anatomic and functional indices derived from scintigraphic and hemodynamic measurements may provide the best assessment of infarct size.
Prediction of late survival in patients with mitral valve disease from clinical, hemodynamic, and quantitative angiographic variables.
Authors: Hammermeister K E , Fisher L , Kennedy W , Samuels S , Dodge H T
Published: June 2012

Late follow-up (average = 7.2 years) has been obtained in 249 patients with mitral valve disease who had quantitative angiographic assessment of left ventricular function at thetime of initial catheterization in the 1960s. Surgically treated patients with mitral valve disease had significantly improved survival as compared to medically treated patients with mitral disease. The subgroup with mixed mitral stenosis and regurgitation and the subgroup with moderate impairment of ejection fraction account for this improved survival in surgically treated patients, which occurred despite greater functional and hemodynamic impairment in the surgical cohorts. Using univariate life table survival analysis, ten variables were found to be predictive of survival in the medical cohort, and three in the surgical cohort. With multivariate Cox's regression analysis, end-diastolic volume and arteriovenous oxygen difference were significantly predictive of survival in the medical cohort; age was predictive of survival in the surgical cohort.
Hemodynamic correlates of saralasin-induced arterial pressure changes.
Authors: de Carvalho J G , Dunn F G , Kem D C , Chrysant S G , Froholich E D
Published: June 2012

Angiotensin antagonists have proved useful in elucidating the clinical role of the renin-angiotensin system; and their diagnostic and therapeutic efficacy in hypertension has been the subject of many reports but the hemodynamic effects remain unknown. Therefore, saralasin was infused intravenously (1.3 mg/min for 30 min) in 26 sodium-depleted patients with hypertension. Systemic hemodynamic alterations were determined before, during, and after infusion. On the basis of mean arterial pressure (MAP) changes, patients were classified as responders, nonresponders, or pressorresponders (MAP changes greater than or equal to 10 mm Hg). MAP fall in responders was achieved through reduced cardiac output and/or total peripheral resistance, with minimal or absent reflexive heart rate increase. In nonresponders, despite no change in MAP, output fell in parallel with stroke index and left ventricular ejection rate, In pressorresponders, saralasin increased vascular resistance. Thus, in addition to variable effects on vascular receptors, saralasin produced inhibitory cardiac effects either through altered venous return or inhibition of contractility.
Recurrent sustained ventricular tachycardia. 1. Mechanisms.
Authors: Josephson M E , Horowitz L N , Farshidi A , Kastor J A
Published: June 2012

The mechanism of recurrent sustained ventricular tachycardia (VT) was evaluated in 21 patients. Re-entry as the mechanism for VT was suggested by a) the reproducible initiation (19) and termination (15) of the arrhythmia by programmed stimulation. The rate, ventricle of origin, and stimulation site determined the method of termination. One VPD was usually required with VT rates less than 175/min and/or ventricle of origin ipsilateral to the stimulation site, while two VPDs were usually required for VT with faster rates originating in a contralateral ventricle. The proximal His-Purkinje system (HPS) was not required for initiation or maintenance of VT. Evidence localizing the site of re-entry to a small portion of the ventricles included: a) ventricular capture by ventricular premature depolarizations (VPDs) or pacing (VP) without terminating VT (5), b) sinus capture following VPDs and/or supraventricular fusions without terminating VT (12), and c) atrial pacing normalizing the QRS and H-V intervals without terminating VT (5).
Characteristics of atrioventricular conduction and the spectrum of arrhythmias in lown-ganong-levine syndrome.
Authors: Benditt D G , Pritchett L C , Smith W M , Wallace A G , Gallagher J J
Published: June 2012

Electrophysiological characteristics of atrioventricular (A-V) conduction and refractoriness were examined in 12 patients with Lown-Ganong-Levine (LGL) syndrome referred for assessment of the following arrhythmias: (group I) regular narrow QRS tachycardia 6/12 (50%), (group II) atrial fibrillation (AF) 2/12 (17%), group III) ventricular tachycardia (VT) 4/12 (33%). A-V node refractory periods were shorter, and enhanced A-V conduction more frequent (7/12, 58% vs 7/28, 25%) in LGL patients compared to similar studies in 28 normal controls. During laboratory study reciprocating tachycardia (RT) due to re-entry within the A-V node occurred in 4/12 (33%) LGL patients, and exhibited a shorter cycle length (294 +/- 60.4 msec) than did the same arrhythmia in 11/28 (39%) controls 372 +/- 51.8 msec, P less than 0.05). Similarly, RT utilizing a concealed accessory pathway had a shorter cycle length (228 +/- 3.5 msec) in 2/12 (17%) LGL patients than in 11/28 (39%) controls (314 +/- 24.3 msec, P less than 0.001). In AF, the shortest R-R intervals in 4/12 (33%) LGL patients (2 group I, 2 group II) were shorter than in 15/28 (54%) control patients (254 +/- 42.2 msec vs 325 +/- 64.2 msec, P less than 0.05). The mean R-R internvals did not differ significantly (LGL 372 +/- 89 msec vs control 428 +/- 82.6 msec). This study suggests that the characteristics of A-V conduction and refractoriness may permit development of more rapid heart rates during certain arrhythymias in LGL patients compared to normal controls. Furthermore, the occurrence of VT in patients with LGL sydrome indicates that symptomatic arrhythmias require specific diagnosis.
Normalization of bundle branch block patterns by distal His bundle pacing. Clinical and experimental evidence of longitudinal dissociation in the pathologic his bundle.
Authors: El-Sherif N , Amay-Y-Leon F , Schonfield C , Scherlag B J , Rosen K , Lazzara R , Wyndham C
Published: June 2012

Clinical and experimental observations in which bundle branch block patterns (BBBP) in ECG leads were normalized by distal His bundle (H) pacing are reported. The clinical material includes four patients with acute right BBBP secondary to anterior wall myocardial infarction and three patients with chronic left BBBP. Six of the seven patients had a prolonged H-V interval (60-85 msec) including three who showed evidence of an intra-H conduction delay (IHCD) with split H (H and H'). Distal H pacing from a right-sided electrode catheter normalized the BBBP with a stimulus-to-QRS (PI-V) interval 20-35 msec shorter than the H-V interval and almost identical to the H'-V interval in the three patients with documented IHCD. In 18 dogs ligation of the anterior septal artery resulted in IHCF with split H associated with right or left BBBP. Distal H pacing from catheter and/or plunge wire electrodes normalized the BBBP in 12 experiments (67%) with a PI-V interval identical to the H'-V interval. H pacing was selective and direct stimulation of myocardium was excluded by monitoring the high ventricular septal electrogram. The clinical and experimental observations are discussed as evidence that functional longitudinal dissociation is probably only operative in the pathologic H due to selectively greater depression of conduction in the transverse interconnections.
Cross-sectional echocardiographic characterization of aortic obstruction. 1. Supravalvular aortic stenosis and aortic hypoplasia.
Authors: Weyman A E , Caldwell R L , Hurwitz R A , Girod D A , Dillon J C , Feigenbaum H , Green D
Published: June 2012

Cross-sectional echocardiographic and cineangiographic studies of the left ventricular outflow tract and ascending aorta were performed in five patients with supravalvular aortic stenosis (four hourglass and one hypoplastic). Visualization of the area of obstruction was possible in each patient using the cross-sectional system. In each case the echocardiographically determined diameter at the level of obstruction was within 3 mm of the similar angiographic value. Assessment of the extent of the lesion was possible in four of five cases. In three of these four cases the echocardiographic measurement was within 5 mm of the angiographic measurement while in the fourth the obstruction was felt to involve the total ascending aorta by both techniques. Determination of percent decrease in LVOT diameter from the aortic anulus to the level of obstruction was useful in defining obstruction and estimating severity. Cross-sectional echocardiography is a valuable noninvasive method for evaluating the ascending aorta in patients with supravalvular aortic stenosis.
Apex echocardiography. A two-dimensional technique for evaluating congenital heart disease.
Authors: Silverman N H , Schiller N B
Published: June 2012

We have evaluated apex echocardiography, using an 80 degrees phased array sector scanner, in 368 patients with congenital heart disease. With the patient lying with the left side dependent, the transducer is placed over the apex of the heart and cross sectional images are obtained in the plane perpendicular to the cardiac septa and through the orifices of the mitral and tricuspid valves. In this view, the chambers are side by side and both atria and ventricles are separated by their respective septa and atrioventricular valves. Defects in the region of the septa can be detected. Congenital defects involving the atrioventricular valves, such as endocardial cushion defects, tricuspid atresia, and Ebstein's anomaly, can be defined. The location of the baffle after Mustard's operation for aortopulmonary transposition and intra-atrial structures, such as the membrance in cor triatriatum, can be seen. The position of the apex of the heart can be located in dextro, levo, or mesocardia by definition of the apex image. The relative size of the ventricular septum can be identified with the apex image. We have found this technique to be valuable in patients with congenital heart disease who are undergoing cross sectional echocardiography.
Disproportionate ventricular septal thickening in the developing normal human heart.
Authors: Maron B J , Verter J
Published: June 2012

A disproportionately thickened ventricular septum containing numerous disorganized cardiac muscle cells is the most characteristic anatomic feature of hypertrophic cardiomyopathy. Since information concerning ventricular wall thicknesses and cellular arrangement in the developing heart may be pertinent to understanding the genesis of hypertrophic cardiomyopathy, morphologic observations were made in 151 normal human embryos, fetuses and term infants. Disproportionate ventricular septal thickening (septal-free wall ratio greater than or equal to 1.3) was present in 94% of embryos and young fetuses; in over one-third disproportionate thickening was particularly pronounced (septal-free ratio greater than or equal to 2.0). Disproportionate septal thickening was also present in 65% of older fetuses, but in only 12% of infants over two weeks of age. Septal-free wall ratio decreased in a curvilinear fashion with increasing age and apporixmated unity in the newborn. This phenomenon occurred because, while both ventricular septal and left ventricular free wall thicknesses increased directly with age, free wall thickness increased at a greater rate than septal thickness, particularly after birth. Marked cellular disorganization in the septum was not a feature of the hearts studied.
Effects of dimethyl propranolol (UM-272; SC-27761) on myocardial ischemic injury in the canine heart after temporary coronary artery occlusion.
Authors: KU D D , Lucchesi B R
Published: June 2012

Myocardial ischemic injury after temporary occlusion of the left anterior descending coronary artery (LAD) for 90 min followed by reperfusion was estimated from the epicardial ST-segment elevation 15 min after occlusion (ST15m), changes in QRS complex, myocardial creatine kinase (CPK) activity and nitro-blue-tetrazolium (NBT) staining at 24 hours. At all sites exhibiting ST15m greater than 2 mV, there was a small development of epicardial Q waves after 90 min of occlusion (sigma deltaQ = 6.94 +/- 0.52 mV) and was maintained for 24 hours. Good correlations were obtained between CPK activity at 24 hours and the development of Q waves at 24 hours as well as at 60 min after reperfusion (r = 0.49; N = 56). Pretreatment with UM-272 significantly reduced the development of Q-waves (sigma deltaQ1hr = 2.23 +/- 0.75 mV) which was correlated with less CPK depletion and smaller infarct size as determined on the bais of NBT staining for myocardial tissue dehydrogenases at 24 hours. It appears, therefore, that the assessment of pathoologic Q wave development provides an accurate and early estimate of the extent of the ultimate cardiac damage due to ischemia and that pretreatment with UM-272 exerts a protective effect on the ischemic myocardium.
Hemodynamic effects of nitroprusside and hydralazine in experimental cardiac tamponade.
Authors: Fowler N O , Gabel M , Holmes J C
Published: June 2012

Cardiac tamponade is associated with decreased cardiac output and increased systemic vascular resistance. Thus, vasodilator drugs might lower systemic resistance and increase cardiac output. Three groups of dogs were studied during tamponade. Group I received nitroprusside only; group II received blood transfusion and then nitroprusside; group III received hydralazine. In group I, nitroprusside lowered right artrial pressure and systemic resistance; cardiac output was unchanged. In group II, transfusion raised right atrial pressure but not cardiac output. Then nitroprusside raised cardiac output significantly. Hydralazine decreased right atrial pressure less than nitroprusside but decreased vascular resistance and raised cardiac output. Both nitroprusside and hydralazine decreased systemic vascular resistance during tamponade, but only hydralazine raised cardiac output probably because of its lesser effect upon the capacitance vessels. Nitroprusside maintained cardiac output during tamponade despite lowered right atrial pressure but increased cardiac output only after transfusion.
Reduced left ventricular myocardial blood flow per unit mass in aortic stenosis.
Authors: Johnson L L , Sciacca R R , Ellis K , Weiss M B , Cannon P J
Published: June 2012

Myocardial blood flow (MBF) per unit mass was measured in 10 patients (pts) with severe aortic stenosis (AS) and no significant aortic insufficiency, normal ejection fractions, and normal coronary arteriograms, using xenon-133 and a multiple crystal scintillation camera. MBF per unit mass was reduced in AS (53 +/- 13 mg/100g.min) in comparison to a group of seven normal control patients (69 +/- 12 ml/100g.min) (P less than 0.05). When normalized for heart rate. MBF remained depressed in aortic stenosis (0.65 +/- 0.11 ml/100 g.beat). MBF/beat was strongly related to peak left ventricular wall stress in both groups (r = 0.97). Individual values of MBF/beat were normalized for peak stress using an analysis of covarience; the adjusted mean values were 0.62 +/- 0.03 ml/100g.beat for the AS patients and 0.84 +/- 0.03 ml/100 g.beat for the control patients. There was no overlap between groups in adjusted MBF per beat. Values of MBF per beat and peak stress for a group of ten cardiomyopathy patients with depressed contractility were observed to fall close to the regression line for AS patients. The results suggest that variability in resting MBF in these AS patients is due primarily to differences in LV stress and that reduction in MBF per beat in this group may be due to reduced contractility.
Spectral energy of the first heart sound in acute myocardial ischemia. A correlation with electrocardiographic, hemodynamic, and wall motion abnormalities.
Authors: Clarke W B , Austin S M , Shah P M , Griffin P M , Dove J T , McCullough J , Schreiner B F
Published: June 2012

First heart sound (S1) energy spectra in isovolumic systole, hemodynamics, and angiographic left ventricular wall motion (LVWM) at rest and with atrial pacing were compared in 27 patients who underwent diagnostic cardiac catheterization and angiography because of chest pain. Eighteen patients were found to have coronary artery disease (CAD) and nine patients, normal coronary arteries. Eleven of the 18 CAD patients (61%) had a mean reduction in the spectral energy of S1 of 6.5 +/- 1.4 (SEM) dB below control (-52%), during interruption of ischemic stress of rapid atrial pacing, compared to only one of nine patients without CAD (P less than 0.05). Only five CAD patients (28%) had an abnormal rise (greater than or equal to 5 mm) in left ventricular end-diastolic pressure (LVEDP) either during or upon interruption of pacing, and six (33%) had ischemic ST-segment depression greater than or equal to mv in the ECG. Similarly two patients free of CAD (22%) had an abnormal increase in LVEDP, and none had ECG evidence of ischemia. Seventeen CAD patients (94%) had segmental LVWM abnormalities at rest or with interruption of pacing, while three patients with normal coronary arteries (33%) had abnormal angiographic LVWM (P less than 0.01). Thus, reduction is S1 spectral energy is a common accompaniment of myocardial ischemia. In the present study, it was more frequently observed than abnormalities in either the ECG or LVEDP, but was not was consistently seen as segmental left ventricular wall motion abnormalities.
The limitations of epicardial mapping as a guide to the surgical therapy of ventricular tachycardia.
Authors: Spielman S R , Michelson E L , Horowitz L N , Spear J F , Moore E N
Published: June 2012

The adequacy of intraoperative epicardial mapping as a guide to surgical procedures performed to terminate ventricular arrhythmias was investigated. Ligation of the anterior septal or left anterior descending coronary artery in 28 dogs produced ventricular arrhythmias that were studied 24-36 hours following occlusion. The sites of origin of 26 tachycardias were determined to be in the subendocardium by using extensive epicardial, endocardial and intramural mapping techniques and were verified by demonstrating unaltered activation sequences during pacing from these earliest sites. Epicardial breakthrough followed earliest directly recordable ventricular activity by as little as 7 msec. Without endocardial mapping many of these tachycardias would have been incorrectly identified as originating in the fascicles or epicardium. The sites of epicardial breakthrough were anatomically distant from the sites of origin by a markedly varying extent (5mm to 6cm). Two rhythms might be close in their sites of earliest epicardial appearance yet distant on the endocardium or vice versa. We conclude that epicardial mapping may not be sufficient to identify or predict the origins of many ventricular tachycardias and that the success of surgery to abolish these arrhythmias may be enhanced by preoperative and intraoperative endocardial mapping.
Determinants of antegrade echo zone in the Wolff-Parkinson-White syndrome.
Authors: Pritchett E L , Gallagher J J , Scheinman M , Smith W M
Published: June 2012

Forty-five patients with the Wolff-Parkinson-White syndrome and reciprocating tachycardia which utilized the atrioventricular (A-V) node for antegrade conduction and an accessory pathway for ventriculo-atrial (retrograde) conduction were studied. The extrastimulus technique in the right atrium and coronary sinus at multiple pacing cycle lengths was used. Three types of "echo zones" were defined by the relationship of the antegrade effective refractory period (ERP) of the accessory pathway, the longest coupling interval accompanied by an atrial echo, the ERP of the A-V node, and the functional refractory period of the atrium. Eighteen of 45 patients (40%) had more than one type of echo zone demonstrated by changing either pacing site or pacing cycle length or both. Pacing site and intraventricular conduction delay were found to have important effects on the longest coupling interval accompanied by an atrial echo in those echo zones in which the longest coupling interval accompanied by an atrial echo was less than the antegrade ERP of the accessory pathway. The echo zone is a useful concept to explain the physiology of the common reciprocating tachycardia in patients with the Wolff-Parkinson-White syndrome. However, the echo zone is profoundly affected by pacing site and pacing cycle length. When these variables are changed, many patients can be shown to have more than one type of echo zone. Studies of the echo zone have limited value as therapeutic guides.
The risk of advanced heart block in surgical patients with right bundle branch block and left axis deviation.
Authors: Pastore J O , Yurchak P M , Janis K M , Murphy J D , Zir L M
Published: June 2012

The risk of advanced atrioventricular block during anesthesia was studied prosepctively in 44 patients with right bundle branch block and left axis deviation who underwent a total of 52 operations over a 14 month period. All patients had continuous electrocardiographic monitoring throughout anesthesia induction, operation, and surgical recovery. Of the 52 operative procedures, 24 were done under general anesthesia, 11 under spinal, and 17 under local. The preoperative cardiac rhythms were atrial fibrillation in two patients, atrial tachycardia with block in one patient, atrial flutter in one patient, and sinus rhythm in the remaining patients. Temporary pacemakers were inserted preoperatively in six patients, usually because of PR interval prolongation on the preoperative electrocardiogram. There was only one episode of transient complete heart block in 51 of the 52 operative procedures. In two of the six patients with temporary pacemakers, significant pacer-related ventricular irritability occurred. This study indicates that temporary pacemaker insertion is rarely required in patients with chronic right bundle branch block and left axis deviation who require noncardiac surgery.
Clinical electrophysiologic effects of tocainide.
Authors: Anderson J L , Mason J W , Winkle R A , Meffin P J , Fowles R E , Peters L , Harrison D C
Published: June 2012

The electrophysiologic properties of tocainide were evaluated by electrophysiologic studies in 11 patients before, during and after a constant intravenous infusion of the drug for 15 minutes. Peak plasma tocainide concentrations averaged 11.0 +/- 1.7 microgram/ml (SEM), range 3.7 to 22.7. AH, HV, QRS, QTc and RR intervals were measured every 5 minutes during sinus and atrial-paced rhythms and showed small changes which were not statistically significant for HV and QRS. Mild shortening of RR was significant (P less than 0.05) at 15 minutes only. AH tended to increase slightly for spontaneous (but not paced) rhythm, becoming significant at 15 minutes only (P less than 0.05). QTc decreased slightly, a change which was significant (P less than 0.05) for paced but not spontaneous rhythm. A progressive rise in mean arterial pressure occurred during infusion and persisted through 30 minutes (P less than 0.001). Comparison of electrophysiologic studies at 0 and 30 minutes showed decreased in mean effective refractory periods of atrium, A-V node, and right ventricle by 17, 22, and 23 msec, respectively (P less than 0.05, 0.01, 0.01). Functional refractory period of the A-V node showed an average decrease which was not significant. Sinus node recovery time and Wenckebach cycle length were unchanged. The drug was well tolerated in all 11 patients. Hypotension in a twelfth patient may or may not have been drug related. These results obtained at therapeutic plasma concentrations suggest qualitative similarities between the conduction system effects of tocainide and those published for lidocaine.