Prognostic implications of rest and exercise radionuclide ventriculography in patients with suspected or proven coronary heart disease

Rest and exercise radionuclide ventriculography were assessed for their value in predicting major cardiac events in patients with chest pain. Of 219 patients who were followed for up to 51 months, 42 had major cardiac events: 12 patients (5.5%) died, 5 (2.2%) sustained nonfatal myocardial infarction, and 25 (11.4%) had coronary arterial bypass grafting. Univariate and multivariate survival analysis revealed that exercise left ventricular ejection fraction was the best predictor for total major events and the resting ejection fraction to be the best predictor for death or nonfatal myocardial infarction. These two variables were strong predictors in the entire group of patients and in subgroups: patients with or without Q-wave infarction, patients with high probability of coronary artery disease and those with abnormal resting left ventricular function. Thus, radionuclide angiography provides important prognostic data that permits the physician to categorize patients with chest pain syndromes with respect to subsequent cardiac events. If validated, this model or a modification of it could identify patients at high risk of subsequent major cardiac events who are candidates for intensive follow up and therapy or further invasive evaluation, as well as patients at low risk of subsequent major cardiac events for whom standard follow up would be appropriate.     

Electrocardiographic and serum enzymic alterations associated with cardiac alterations induced in dogs by single transthoracic damped sinusoidal defibrillator shocks of various strengths.

The safety margin between the strength of shock needed to defibrillate the ventricle and shocks which produce cardiac damage has not previously been reported. This study quantitates the shock intensity required to produce ECG alterations, serum alpha-1LDH and MB CPK isoenzyme elevation and myocardial damage using single transchest damped sinusoidal defibrillator shocks. Shocks of 1 to 20 amperes per Kg. of body weight were applied. Fifty-six dog weighing 2.4 to 15 kilograms were shocked with defibrillator pulses via 10 centimeter diameter electrodes applied to the thorax. Electrocardiograms were taken to be analyzed for arrhythmias, S-T segment changes, and T wave changes. Serum enzyme levels were determined in 25 dogs. Macroscopic and histopathologic studies were conducted on the hearts. Transchest single damped sine wave shocks did not produce microscopically detectable cardiac damage until at least a threefold current overdose was applied. No macroscopic morphologic alterations were observed until at least a sixfold current overdose was applied and no deaths occurred until a twelvefold or greater current overdose was delivered. Incidence and severity of ECG changes, increase in serum enzyme activity, incidence and severity of cardiac damage, and incidence of mortality all correlated positively with shock strength. However, these four adverse effects did not correlate well with each other. Transient ECG changes were very frequent following shock application regardless of the morphologic damage produced, and hence the transient changes have little value as indicators or predictors of damage. Persistent ECG changes were predictive of morphologic changes but were not sensitive enough to detect damage in mildly injured hearts. Likewise, elevated serum cardiac isoenzyme activity was a reliable but insensitive indicator of damage.     

Postpartum cardiac failure—heart failure due to volume overload?

Ventricular function has been studied in 43 patients with the peripartum cardiac failure (PPCF) syndrome which occurs around Zaria. All patients had an echocardiogram on admission and 10 patients had right heart catheterization. Despite the gross edema, left ventricular function assessed by echocardiography and systolic time intervals was relatively good and the estimated cardiac output were high. At catheterization, although the pressures were high, the cardiac outputs were greater than normal in four out of six patients. No patient had a low cardiac output. These findings are not compatible with a severe heart muscle disorder, or cardiomyopathy. We suggest that the primary event in PPCF of Zaria is fluid retention which leads to a form of high output cardiac failure. The postpartum practices in this area (taking high sodium diets and lying on heated beds) almost certainly cause the fluid to accumulate initially, but the heart may be unable to meet the demands either because of preexisting heart muscle disease or, more likely, because of a rise of the peripheral resistance due to the volume expansion, overburdens such dilated hearts and leads to myocardial damage. Since there are similarities between this condition and PPCF in temperate climates, it is possible that there is a common mechanism which the traditional practices of this area have unveiled.     

Cardiac abnormalities in cachectic patients before and during nutritional repletion.

The effect of PCU and HA on heart dimensions and function was examined with non-invasive methods in 10 patients with severe undernutrition of diverse etiology. Control subjects were 10 normal men and women matched to their cachectic counterparts by height and sex.The study was conducted in two phases. In phase A, baseline studies of heart dimensions and function were completed. Phase B consisted of cardiovascular and metabolic monitoring during 4 to 6 weeks of enteral or parenteral HA.Phase A was characterized by a reduced radiographic total heart volume, echo EdV, LV mass, and CO. These reductions, however, were only one half to one eighth as great as the losses in BW. The patients therefore entered HA with an elevated LV mass index and cardiac index. Ejection phase indices of LV function (EF and Vcf) were normal or enhanced.Phase B studies in five subjects showed that decreased cardiac size and output were correctible by HA, but at differing rates. Ventricular volume and CO corrected more rapidly than LV mass under the conditions of rapid repletion where the daily sodium intake was 2 to 4 grams, and values for cardiac index reached 250 per cent of normal. Resting metabolic rate also increased during phase B. The combination of an elevated output, excessive sodium retention, and increased metabolic rate while LV mass was still reduced appeared to be responsible for cardiac decompensation in two of five repleted patients.To prevent cardiac decompensation during the HA of undernourished subjects, we propose the use of low salt regimens, a slower rate of HA and serial monitoring of cardiac dimensions and function by clinical examination and echo.     

The risk of diagnostic cardiovascular catheterization.

This report details a prospective study of the risk of diagnostic cardiac catheterization performed in a private, community hospital. Over the first 131 months of operation of our laboratory, 745 adult patients underwent diagnostic cardiac catheterization consisting of 2,676 various catheterization procedures. Six patients experienced seven major complications; two of these complications left a permanent deficit. There were no deaths during catheterization and none later which were attributable to it. The risk to the patient of having a major complication associated with a cardiac catheterization in our series was 0.8 per cent. The risk to the patient of having a major complication when a catheterization procedure was performed was 0.3 per cent. The risk of having a complication resulting in a permanent sequela was 0.07 per cent. We conclude that diagnostic cardiac catheterization can be accomplished with little risk to the patient, either of death or of other major complication.     

Direct and reflex cardiac bradydysrhythmias from small vagal nerve stimulations

Alterations in cardiac pacemaker location, its rate of discharge, and A-V conduction patterns were induced in anesthetized adult dogs by electrical stimulation of the thoracic vagi and their small cardiac branches before and after cervical vagotomy. Electrical activity from small, contiguous bipolar silver electrodes was amplified and recorded by an optical oscillograph. The electrodes were located over the SA node, the three internodal pathways, the left atrium, and ventricular epicardium. A Hoffman-type plaque electrode was placed over the A-V node to record a His bundle electrogram simultaneously with a Lead II electrocardiogram. Electrical stimulation of the intact left recurrent laryngeal nerve and its cardiac branches before and after vagotomy induced both direct and reflex effects on SA nodal cycle length. Efferent dromotropic effects on the A-V node varied from first- to third-degree heart block during stimulation of individual left recurrent cardiac branches. Stimulation of the right recurrent cardiac nerve induced atrial bradycardia with heart block above the His bundle. Stimulation of individual right vagal branches near the heart induced bradycardia, cardiac asystole, shifts in atrial pacemaker location, or activation of His pacemakers. Establishment of the His rhythm probably indicates selective inhibition of supraventricular pacemakers but not of the His bundle. Asystole and His rhythms induced during stimulation of the more caudal branches of the right cardiac vagal nerves were generally reflexly mediated and were abolished by cervical vagotomy.     

Effect of experimental hyperthyroidism on protein turnover in skeletal and cardiac muscle

Since experimental hyperthyroidism reduces skeletal muscle mass while simultaneously increasing cardiac muscle mass, the effect of hyperthyroidism on muscle protein degradation was compared in skeletal and cardiac muscle. Pulse-labeling studies using (³H) leucine and (¹⁴C) carboxyl labeled aspartate and glutamate were carried out. Hyperthyroidism caused a 25%–29% increase in protein breakdown in both sarcoplasmic and myofibrillar fractions of skeletal muscle. Increased muscle protein degradation may be a major factor in the development of skeletal muscle wasting and weakness in hyperthyroidism. In contrast, protein breakdown appeared to be reduced 22% in the sarcoplasmic fraction of hyperthyroid heart muscle and was unchanged in the myofibrillar fraction. Possible reasons for the contrasting effects of hyperthyroidism on skeletal and cardiac muscle include increased sensitivity of the hyperthyroid heart to catecholamines, increased cardiac work caused by the hemodynamic effects of hyperthyroidism, and a different direct effect of thyroid hormone at the nuclear level in cardiac as opposed to skeletal muscle.     

Use of phentolamine in acute myocardial infarction

Right-sided cardiac pressures were obtained with a Swan-Ganz catheter in 10 patients within the first 24 hours after a myocardial infarction. Brachial artery pressures were obtained with a Cournand needle. Cardiac pressures and arteriovenous oxygen differences were obtained before and immediately after the 30-minute infusion of phentolamine, administered at 0.4 mg. per minute. Seven patients were normotensive, 2 were hypotensive, and 1 was hypertensive. With phentolamine, all of the patients demonstrated a significant decrease in the right and left ventricular filling pressures, a rise in the cardiac index, and a small decrease in the arterial pressure. Phentolamine can greatly improve cardiac function, in acute myocardial infarction, regardless of the level of the initial blood pressure.     

Asymptomatic electrocardiographic alterations in sarcoidosis

Among 80 patients with tissue-confirmed sarcoidosis attending the sarcoidosis clinic of the Mount Sinai Hospital, electrocardiographic abnormalities of varying degree were noted in 41 patients, despite the fact that these patients were entirely without cardiac complaints and exhibited no evidence of previous or current cardiac disease on thorough examination. All these patients were under 40 years of age.The ECG alterations included repolarization abnormalities and alterations in rhythm and conduction. Because of the potential hazards of some of these abnormalities, prospective studies are being undertaken to determine which of them may represent precursors of dangerous intrinsic cardiac sarcoidosis.     

双心室再同步治疗后无应答发生率及原因分析

目的 观察本中心双心室再同步治疗(CRT)术后无应答的发生率,并分析可能导致无应答的原因.方法 2001年3月至2009年5月119例患者行CRT治疗(男96例,年龄34～82岁),NYHA心功能Ⅲ～Ⅳ级,左心室射血分数≤35%,随访6个月以上.结果 119例患者中,7例在CRT置人后6个月内因不同原因死亡,112例完成6个月以上的随访,无应答发生率为28.57%.多因素logistic回归分析提示心力衰竭病程、肺动脉高压、血清肌酐值增高、完全性右束支传导阻滞及心室电极导线置人位置均是CRT无应答的独立危险因素.在CRT术后6个月时,CRT应答组心力衰竭的常规治疗药物明显减少,主要是洋地黄和利尿剂与无应答组比较差异有统计学意义(P＜0.01＝.结论 CRT术后无应答的发生率为28.57%.完全性右束支传导阻滞虽然也有QRS时限明显增宽,但CRT术后无应答的发生率明显增高.左心室电极导线的位置是决定CRT术后无应答发生的重要环节,心大静脉不宜做左心室电极导线置入的部位.     

Repeat hemodynamic determinations in borderline hypertension

Repeat hemodynamic determinations were performed in 37 young men with borderline hypertension. The duration of the follow up study was 47 ± three months. At each determination, those with borderline hypertension were compared to a group of matched normal subjects. Blood pressure increased from the first to the second determination, but the increase was significant only for systolic (P < 0.001) and mean (P < 0.01) arterial pressures. Cardiac index and heart rate, which were initially increased, decreased significantly (P < 0.02; P < 3.01, respectively) and decreased to normal values; total peripheral resistance increased (P < 0.01); blood and plasma volumes decreased (P < 0.01). At the first determination, the cardiac index-heart rate correlation was significant (P < 0.01) and the cardiac index-blood volume correlation was not. At the second determination, on the contrary, the cardiac index-total blood volume correlation was significant (P < 0.001) whereas the cardiac index-heart rate correlation was not. The study provides evidence that patients with borderline hypertension, over a short-term period, show (1) a greater increase in systolic than in diastolic pressure, (2) a return of cardiac output toward normal values through a decrease both in heart rate and blood volume, and (3) an increased importance of volume factors in the cardiac output control.     

Progression to left ventricular dilatation in patients with hypertrophic obstructive cardiomyopathy

Congestive heart failure with dilated left ventricle developed in two patients with symptomatic hypertrophic obstructive cardiomyopathy. Both patients previously underwent cardiac surgery for relief of their outflow obstruction. Alterations in structure and function of the left ventricle during their episode of cardiac failure and thereafter were documented by echocardiography. The findings suggest that progression to left ventricular dilatation is a potential complication in patients with hypertrophic obstructive cardiomyopathy.     

Maximal cardiac output during exercise in patients with coronary artery disease

Cardiac output, determined by the direct Fick method, was measured each minute during multistage treadmill testing in which patients exercised to the point of exhaustion. Twenty-nine tests and 183 measurements of cardiac output during exercise were performed in 16 patients with coronary artery disease. Maximal cardiac output paralleled the maximal oxygen intake and was reflected by a plateau during the final minutes of exercise. Significant decreases in stroke volume and increases in mean pulmonary arterial pressure suggest that acute left ventricular dysfunction is the mechanism limiting the maximal cardiac output in these patients. Maximal cardiac output is a sensitive and fundamental indicator of the degree of impairment resulting from coronary disease, and has potential value in defining the role of various methods of treating this disease.     

Global Unmet Needs in Cardiac Surgery

More than 6 billion people live outside industrialized countries and have insufficient access to cardiac surgery. Given the recently confirmed high prevailing mortality for rheumatic heart disease in many of these countries together with increasing numbers of patients needing interventions for lifestyle diseases due to an accelerating epidemiological transition, a significant need for cardiac surgery could be assumed. Yet, need estimates were largely based on extrapolated screening studies while true service levels remained unknown. A multi-author effort representing 16 high-, middle-, and low-income countries was undertaken to narrow the need assessment for cardiac surgery including rheumatic and lifestyle cardiac diseases as well as congenital heart disease on the basis of existing data deduction. Actual levels of cardiac surgery were determined in each of these countries on the basis of questionnaires, national databases, or annual reports of national societies. Need estimates range from 200 operations per million in low-income countries that are nonendemic for rheumatic heart disease to >1,000 operations per million in high-income countries representing the end of the epidemiological transition. Actually provided levels of cardiac surgery range from 0.5 per million in the assessed low- and lower-middle income countries (average 107 ± 113 per million; representing a population of 1.6 billion) to 500 in the upper-middle-income countries (average 270 ± 163 per million representing a population of 1.9 billion). By combining need estimates with the assessment of de facto provided levels of cardiac surgery, it emerged that a significant degree of underdelivery of often lifesaving open heart surgery does not only prevail in low-income countries but is also disturbingly high in middle-income countries.     

Constituents of the human ventricular myocardium: connective tissue hyperplasia accompanying muscular hypertrophy

Left-sided congestive heart failure may be secondary to decreased left ventricular myocardial compliance in some patients. To investigate the anatomic basis for altered wall stiffness, morphometric determinations of muscle cell nuclear density and percent of myocardium consisting of muscle cells were made for right and left ventricular free wall and septum in 127 hearts with normal coronary arteries. The hearts were normal (33 patients), had left ventricular hypertrophy (28 patients), right ventricular hypertrophy (25 patients), or chronic dilatation (41 patients). With cardiac enlargement, the average percent of myocardium consisting of muscle did not change from the approximately 75% value characteristic of normal hearts. In contrast, muscle cell nuclear density decreased proportionate to cardiac enlargement, demonstrating that muscle cell hypertrophy, not hyperplasia, is the basis for weight increase. Some hearts with marked longstanding dilatation also had perivascular and interstitital "striae" of connective tissue differing from replacement fibrosis. An increase in epicardial coronary artery caliber commensurate with increased heart weight suggests that ischemia is not the basis of connective tissue increase. The results show that cardiac muscle cell hypertrophy is accompanied by commensurate increase in interstitial connective tissues. This pattern of myocardial growth with cardiac enlargement may produce increased myocardial stiffness simply as a result of increased wall thickness, and may lead to left-sided congestive heart failure.     

Combined nitroprusside-dopamine therapy in severe chronic congestive heart failure. Dose-related hemodynamic advantages over single drug infusions

To assess the circulatory effects of afterload reduction and inotropism individually and in combination as rational therapy for refractory heart failure, nitroprusside and dopamine were administered to 13 patients with severe cardiac decompensation. Dopamine at average doses of 3 and 7 microgram/kg per min produced increases in cardiac output and reductions in peripheral resistance. At doses of 15 microgram/kg per min, dopamine increased heart rate, peripheral arterial pressure and side effects. Nitroprusside alone decreased left-sided filling pressures and increased cardiac output. When the agents were administered together, the increases in cardiac output were significantly greater than with either agent alone and there was physiologic improvement in overall circulatory function. The relations among changes in afterload (systemic impedence), preload (filling pressures) and cardiac index help to explain the salutary effects of combined therapy in patients with refractory heart failure.     

Echocardiographic dimensions in borderline and sustained hypertension.

Echocardiographic dimensions and hemodynamic indexes were determined in 42 patients with borderline hypertension and in 22 with sustained hypertension and the results were compared with findings in 33 normal subjects. In patients with borderline hypertension the thickness of the interventricular septum (IVS) was significantly increased (P less than 0.001), whereas the posterior wall PW) thickness remained within normal range. The IVS/PW ratio was significantly elevated (P less than 0.001) and was correlated negatively with the cardiac index (P less than 0.01) and positively with the preejection period (P less than 0.01). In patients with sustained hypertension a symmetric cardiac hypertrophy was observed, and there was a significant positive correlation between the IVS/PW ratio and diastolic pressure (P less than 0.05). The study suggested that (1) in sustained hypertension the symmetric cardiac hypertrophy was secondary to a progressive increase in pressure load, whereas (2) in borderline hypertension the asymmetric cardiac hypertrophy could not be directly related to the level of blood pressure and was probably associated with abnormalities of the sympathetic nervous system.     

Radionuclide analysis of right and left ventricular response to exercise in patients with atrial and ventricular septal defects

In patients with ventricular or atrial septal defect, the ventricle which is chronically volume overloaded might not appropriately respond to increased demand for an augmentation in output and thereby might limit total cardiac function. In this study we simultaneously measured right and left ventricular response to exercise in 10 normal individuals, 10 patients with ventricular septal defect (VSD), and 10 patients with atrial septal defect (ASD). The normal subjects increased both right and left ventricular ejection fraction, end-diastolic volume, and stroke volume to achieve a higher cardiac output during exercise. Patients with VSD failed to increase right ventricular ejection fraction, but increased right ventricular end-diastolic volume and stroke volume. Left ventricular end-diastolic volume did not increase in these patients but ejection fraction, stroke volume, and forward left ventricular output achieved during exercise were comparable to the response observed in healthy subjects. In the patients with ASD, no rest-to-exercise change occurred in either right ventricular ejection fraction, end-diastolic volume, or stroke volume. In addition, left ventricular end-diastolic volume failed to increase, and despite an increase in ejection fraction, left ventricular stroke volume remained unchanged from rest to exercise. Therefore, cardiac output was augmented only by the heart rate increase in these patients. Right ventricular function appeared to be the major determinant of total cardiac output during exercise in patients with cardiac septal defects and left-to-right shunt.     

Comparison of patients with ischemic, myopathic, and rheumatic heart diseases as cardiac transplant recipients

Fifty-four human-to-human cardiac transplants (10 orthotopic and 44 heterotopic) in 50 patients were performed between December, 1967, and December, 1981. The underlying cardiac pathology was ischemic (IHD) in 29, cardiomyopathic (CM) in 17, rheumatic (RHD) in four, and mixed or other pathology in four. Patients with RHD survived for a mean period over three times as long as those with either CM (p less than 0.02) or IHD (p less than 0.05). Although CM patients were on average over a decade younger than those in other groups, they had a lower survival rate. There was a higher incidence of death from chronic rejection in patients with IHD, in whom there was also a higher incidence of thromboembolic episodes. Major infections were over twice as frequent in IHD patients as in CM patients (p less than 0.01). Noncompliance with regard to adherence to instructions and therapy was a significant factor in morbidity and mortality, especially in CM patients. Our data suggest that survival and morbidity of recipients of heart transplants might be influenced to some extent by the nature of the underlying primary cardiac condition, RHD being considered a favorable survival factor when compared with IHD, and CM being particularly unfavorable.     

Undesirable cardiac arrhythmias associated with rate hysteresis pacemakers

The introduction of the ventricular inhibited pulse generator with the feature of rate hysteresis has been associated with a variety of rhythm disturbances, some causing serious concern. This pulse generator has two different pacing rates: (1) the automatic rate, which is the interval between two successive paced beats (usually 860 msec or 70/min), and (2) the hysteresis interval, which results in a 1,000 msec delay between a sensed cardiac contraction and the next pacemaker discharge. The hysteresis interval after a sensed signal may result in long pauses that may predispose to the development of serious cardiac arrhythmias. Two examples of this type of complication were recently observed. One patient had bigeminal rhythm with mechanically ineffective cardiac contractions and an effective cardiac rate of 35/min; he experienced dyspnea and weakness during these prolonged episodes. Another patient had repeated episodes of ventricular fibrillation. The cardiac arrhythmias were not controlled by antiarrhythmic agents, and both patients required replacement of the pulse generator.The proposed advantages of pulse generator hysteresis are (1) prolongation of battery life, and (2) maintenance of effective atrial transport; these advantages may be outweighed by undesirable cardiac arrhythmias that may be associated with this mode of pacemaker function. Rate hysteresis cardiac pacemakers should be reserved for patients having predominantly sinus rhythm without ventricular irritability. In patients with frequent ectopic ventricular activity, atrial fibrillation or high degree atrioventricular block, the rate hysteresis pacemaker offers no advantage over the conventional demand pacemaker. For patients with frequent ectopic ventricular activity not easily controlled by antiarrhythmic agents, consideration should be given to the use of a permanent demand pacemaker with external rate control, which may provide greater flexibility in arrhythmia management.