Regional effects of propranolol on intraventricular conduction in coronary artery disease.

In canines, propranolol slows conduction in acutely ischemic, but not in normal tissues. To determine propranolol effects on conduction in patients with coronary artery disease, we studied 7 patients after left anterior descending coronary artery bypass graft surgery. Bipolar electrodes were placed in the atrium, left ventricle (in the left anterior descending distribution), and right ventricle. On postoperative day 7, 3 mg propranolol were given intravenously. At a constant artrially paced rate, conduction intervals were measured from the earliest onset of the QRS in 3 simultaneously recorded surface electrocardiogram (ECG) leads to the major deflection of the electrogram recorded from each ventricle. Ten minutes after injection, conduction in the left ventricle was slowed by 4 +/- 0.3 msec (10 +/- 0.9%) and in the right ventricle by 0.4 +/- 0.3 msec (1 +/- 0.9%). QRS duration changed -1 msec (-0.8%). Stimulus to Q, a measure of propranol effect on A-V conduction, changed 16 +/- 2%. The difference in propranolol effects on left and right ventricles was significant (p less than 0.001). We suggest that in patients with coronary artery disease (1) propranolol has local anesthetic effects in slowing conduction; (2) the effects of propranolol vary with the region of ventricular myocardium; and (3) propranolol slows conduction more in the left than right ventricle. This difference may be due to potentiation of drug effects in left ventricular tissue that is abnormal due to chronic coronary artery disease.     

Effects of Increasing Heart Rate Induced by Efferent Sympathetic Neuronal Stimulation, Isoproterenol or Cardiac Pacing on Myocardial Function and Oxygen Utilization

The effects of increasing heart rate by six different methods on cardiac /unction were investigated in 17 open-chest anesthetized dogs. Heart rate was increased approximately 30% by (1) right interganglionic nerve stimulation, (2) atrial pacing, (3) ventricular pacing, (4) atriovenfricular sequential pacing, (5) right stellate ganglion stimulntion, and (6) isoproterenoi administration. During heart rate increases induced by atrial pacing left ventricular intramyocardial pressure, coronary Wood flow, oxygen delivery per unit of myocardial oxygen consumption, and myocardial efficiency were unchanged. Ventricular pacing reduced left ventricular cavity and septal intramyocardial pressure, while circumflex coronary flow increased, resulting in reduced oxygen delivery relative to myocardial oxygen consumption. Similarly, atrioventricu-lar sequential pacing increased circumflex coronary artery flow and myocardial oxygen consumption, and decreased septal intramyocardial pressure and oxygen delivery per unit of myocardial oxygen consumption. Right stellate ganglion stimulation and isoproterenol increased left anterior descending and circumflex coronary artery blood flow, intramyocardial pressure, and myocardial oxygen consumption. Estimated myocardial efficiency (left ventricle) was decreased by ventricular pacing and isoproterenol, and was unchanged by atrial pacing and right interganglionic nerve stimulation. Increases in heart rate induced by right interganglionic nerve stimulation did not alter myocardial oxygen consumption, or the index of cardiac efficiency. It is concluded that augmentation of heart rate by either ventricular or atrioventricular pacing impairs myocardial function so that there is a decrease of left ventricular efficiency, and isoproterenol augments chronotropism and myocardial force relative to cardiac external work so there is a reduction in cardiac efficiency. In contrast, atrial pacing or right interganglionic nerve stimulation augments chronotropism such that myocardial oxygen consumption and efficiency are unchanged.     

Regional Myocardial Perfusion Rates in Patients with Coronary Artery Disease

Regional myocardial perfusion rates were estimated from the myocardial washout of (133)Xenon in 24 patients with heart disease whose coronary arteriograms were abnormal and 17 similar subjects whose coronary arteriograms were judged to be normal. Disappearance rates of (133)Xe from multiple areas of the heart were monitored externally with a multiple-crystal scintillation camera after the isotope had been injected into a coronary artery and local myocardial perfusion rates were calculated by the Kety formula.The mean myocardial perfusion rates in the left ventricle exceeded those in the right ventricle or atrial regions in subjects without demonstrable coronary artery disease. In this group there was a significant lack of homogeneity of local perfusion rates in left ventricular myocardium; the mean coefficient of variation of left ventricular local perfusion rates was 15.8%.In the patients with radiographically demonstrable coronary artery disease, a variety of myocardial perfusion patterns were observed. Local capillary blood flow rates were depressed throughout the myocardium of patients with diffuse coronary disease but were subnormal only in discrete myocardial regions of others with localized occlusive disease. Local myocardial perfusion rates were similar to those found in the group with normal coronary arteriograms in patients with slight degrees of coronary disease and in those areas of myocardium distal to marked coronary constrictions or occlusions which were well supplied by collateral vessels.In subjects with right coronary disease, the mean right ventricular perfusion rates were significantly subnormal; in seven subjects of this group perfusion of the inferior left ventricle by a dominant right coronary artery was absent or depressed. The average mean left ventricular perfusion rate of 12 subjects with significant disease of two or more branches of the left coronary artery was significantly lower than that of the group with normal left coronary arteriograms. In the patients with abnormal left coronary arteriograms, the average coefficient of variation of local left ventricular perfusion rates was significantly increased (24.8%).The studies provide evidence that coronary artery disease is associated with increased heterogeneity of local myocardial perfusion rates. They indicate that radiographically significant vascular pathology of the right or left coronary artery may be associated with significant reductions of myocardial capillary perfusion in the region supplied by the diseased vessel.     

Effects of exerimental right ventricular hypertrophy on myocardial blood flow in conscious dogs.

The effects of right ventricular hypertrophy on the overall and regional distribution of myocardial blood flow in the absence of an elevated coronary arterial driving pressure were evaluated in 18 concscious dogs subjected to a chronic pressure overload of the right ventricle induced by pulmonary artery constriction. The sustained pressure overload for duration of 4--6 wk or 4--5 mo resulted in significant increases in right ventricular mass (45 and 110%, respectively) and right ventricular fiber diameter (22 and 60%, respectively). Moreover, the presence of moderate and severe hypertrophy was associated with marked increases in transmural blood flow per gram to the right ventricle proportional to the observed increases in mass, i.e., of 36 and 109%, respectively, from a normal value of 0.67 +/- 0.04 ml/min per g, whereas left ventricular blood flow remained unaltered from a normal value of 1.00 +/- 0.06 ml/min per g. Despite the large increase in blood flow per gram to moderately and severely hypertrophied right ventricle, no significant changes in the ratio of capillary:muscle fiber number were observe. These data suggest that the development of right ventricular hypertroph is characterized by a sustained compensatory response of the coronary circulation to the augmented work load and mass, and that is not associated with a proliferative response of the vasculature supplying the enlarged ventricle.     

电子束CT技术诊断冠状动脉瘘的临床应用价值

目的 探讨冠状动脉瘘的电子束CT（EBCT）征象。方法 对经EBCT工手术证实的10例冠状动脉瘘行回顾性分析。本组男7例，女3例，年龄2岁至55岁，中位年龄为48岁。EBCT检查均采用单层增强扫描。结果 EBCT提示6例右侧冠状动脉扩张迂曲，其中5例与扩大的心室腔沟通，另1例近段与主肺动脉沟通；4例冠状动脉瘘源于左侧冠状动脉，其中1例左侧对角支粗大，局部囊状扩张钙化，与左室腔沟通，2例左侧圆锥支与主肺动脉连接，最后1例左侧冠状动脉主干及回旋支扩张钙化，后者经左房前间隙经后壁与右房沟通。结论 EBCT提示冠状动脉及其分支扩张迂曲，与心腔或其他血管异常沟通，应首先考虑冠状动脉瘘。     

Performance of the right ventricle under stress: relation to right coronary flow

Right ventricular performance was studied relative to right coronary artery flow in the chloralose-anesthetized, open chest dog. The right coronary artery was cannulated for measurement and control of flow and pressure. Under control conditions, right coronary artery occlusion caused no change in cardiac output, or right and left ventricular pressures, although right ventricular contractile force fell markedly. With right coronary artery flow intact, incremental pulmonary artery obstruction caused a corresponding decline in cardiac output and elevation of right ventricular end-diastolic pressure with eventual total right ventricular failure and systemic shock. With right coronary artery occlusion, identical degrees of pulmonary artery obstruction resulted in more pronounced changes in cardiac output and right ventricular end-diastolic pressure with right ventricular failure occurring at a much lower level of right ventricular stress.     

Isolated right ventricular infarction: a rare complication of coronary artery dissection

Infarction of the right ventricle generally occurs in association with posterior left ventricular infarction, and isolated right ventricular infarction is unusual. We have reported a case of acute infarction of the right ventricle unassociated with infarction of the left ventricle in a patient with type I aortic dissection that extended into the right coronary artery, resulting in near-complete occlusion of its lumen. We believe that poor collateral circulation of the myocardium played a major role in the pathogenesis of isolated right ventricular infarction after sudden occlusion of the right coronary artery.     

冠心病左室结构与功能相关关系的临床分析

目的　探讨冠心病不同阶段的检查结果与心脏结构、功能关系。方法　通过对 2 2 6例患者临床资料的分析 ,对比心绞痛和心肌梗死对左室结构和功能的影响。结果　主动脉内径、左房内径、左室舒张期内径、舒张末期容积、收缩末期容积、每搏输出量、心输出量、平均室壁厚度和左室心肌质量等参数冠心病各组较正常组有增加的趋势而射血分数、左室短轴缩短率降低 ,收缩功能参数与心室结构变化有关 ;舒张早期血流的峰值流速随心肌损害加重而减低 ,舒张功能参数与冠状动脉严重程度密切相关。冠心病冠状动脉造影阴性损害也同样大。结论　冠心病人出现心室重构 ,收缩、舒张功能逐渐恶化。因此 ,控制心室重构意义重大。     

Echocardiographic diagnosis of the aorto-left ventricular tunnel

AIM/METHOD: The aorto-left ventricular tunnel (ALVT) is a rare congenital cardiac malformation with clinical findings of severe aortic insufficiency. We report the echocardiographic differentiation of different anatomical variants of ALVT in two infants. RESULTS: Echocardiography in both patients demonstrated severe enlargement of the ascending aorta and the left ventricle. In the first patient the ALVT originated from the ascending aorta above the right coronary sinus and entered the left ventricle just below the aortic valve. In the second patient the ALVT originated above the left coronary sinus and took a lateral course to the left ventricle. Colour-Doppler-sonography in both patients confirmed a systolic-diastolic flow across the tunnel. Many patients have associated cardiac defects. Exact determination of the morphology of the aortic valve and coronary arteries is mandatory for surgical repair. Postoperative follow-up studies focus on the function of the aortic valve and the left ventricle. CONCLUSION: Differentiation of different anatomical variants of ALVT is possible trough echocardiography. Cardiac catheterization is required only in cases with inadequate information about coronary artery anatomy.     

Right ventricular infarction: specific requirements of management.

The principal cause of right ventricular infarction is atherosclerotic proximal occlusion of the right coronary artery. Proximal occlusion of this artery leads to electrocardiographically identifiable right-heart ischemia and an increased risk of death in the presence of acute inferior infarction. Clinical recognition begins with the ventricular electrocardiographic manifestations: inferior left ventricular ischemia (ST segment elevation in leads II, III and aVF), with or without accompanying abnormal Q waves and right ventricular ischemia (ST segment elevation in right chest leads V3R through V6R and ST segment depression in anterior leads V2 through V4). Associated findings may include atrial infarction (PR segment displacement, elevation or depression in leads II, III and aVF), symptomatic sinus bradycardia, atrioventricular node block and atrial fibrillation. Hemodynamic effects of right ventricular dysfunction may include failure of the right ventricle to pump sufficient blood through the pulmonary circuit to the left ventricle, with consequent systemic hypotension. Management is directed toward recognition of right ventricular infarction, reperfusion, volume loading, rate and rhythm control, and inotropic support.     

Cardiac function in open-chest dogs after left to right ventricular shunting and right coronary artery occlusion

Summary. Patients with acquired ventricular septal defect (VSD) after myocardial infarction have a particularly bad prognosis if right ventricular function is severely impaired. The significance of an ischaemic right ventricular free wall on cardiac function during interventricular shunting was examined in open-chest dogs. An external interventricular shunt could be opened and closed at will, and by occlusion of the right coronary artery (RCA), a part of the right ventricular free wall was rendered ischaemic. Aortic flow decreased by 8±2% when the shunt was opened in the presence of a normal right ventricle, and by 16±2% (difference: P<0.05) in the presence of right ventricular ischaemia. Aortic flow fell by 19±3% when the RCA was occluded. Right ventricular dyskinesia was demonstrated after occlusion of RCA, by recording segment lengths in the right ventricular free wall. The dyskinesia was aggravated when the shunt was opened. The left ventricle exerted a ‘negative’ work on the ischaemic right ventricular free wall. Retention of blood in the right ventricle, with a subsequent decline in left ventricular filling and an almost unchanged interventricular shunting of blood, explain why aortic flow fell more when the shunt was opened in the presence of right ventricular ischaemia.     

Coronary artery anomalies on preoperative cardiac CT in children with tetralogy of Fallot or Fallot type of double outlet right ventricle: comparison with surgical findings

Coronary artery anomalies on preoperative cardiac CT have not been systematically compared with surgical findings in a large cohort of tetralogy of Fallot and Fallot type of double outlet right ventricle. This study was conducted to evaluate incidence and diagnostic accuracy of preoperative cardiac CT for identifying detailed coronary artery anatomy in these patients. Coronary artery anatomy on preoperative cardiac CT exams in 318 children with tetralogy of Fallot or Fallot type of double outlet right ventricle were reviewed and compared with surgical findings. Incidences of total and surgically critical coronary artery anomalies, concordance rate between cardiac CT and surgical findings, and diagnostic accuracy of cardiac CT were assessed. In addition, the types of surgical modifications for surgically critical coronary artery anomalies were reviewed. The incidences of total and surgically critical coronary artery anomalies were 8.5% (27/318) and 5.0% (16/318), respectively. The concordance rate between cardiac CT and surgical findings was 95.0% (302/318). The diagnostic accuracy of cardiac CT was 96.9% (308/318). In surgically significant coronary artery anomalies, tailored and careful right ventriculotomy was done in 13 cases, placement of a right ventricle–pulmonary artery conduit in two, and unroofing of the right coronary artery in one. Preoperative cardiac CT may be useful in identifying coronary artery anatomy in children with tetralogy of Fallot or Fallot type of double outlet right ventricle.     

超声心动图评价妊娠对母体心脏腔室大小和功能的影响

目的 探讨超声心动图评价妊娠对母体心脏结构和功能影响的l临床价值.方法 测定52例妇女妊娠期与产后6个月的心脏腔室大小指标:左室舒张末内径(LVIDd)、左室收缩末内径(LVIDs)、左房内径、右室横径、右房内径、主动脉内径、肺动脉内径;心脏功能指标:左室射血分数(INEF)、每搏输出量、心输出量、心指数、心房收缩期左室充盈峰速度与舒张早期左室充盈峰速度的比值(A/E)、肺动脉收缩压(PASP).选取40例健康未孕妇女为对照组,测量相同指标.结果 与对照组及产后组比较,妊娠组中50例LVIDd、INIDs、肺动脉内径、心输出量、心指数、LVEF、A/E比值均增高(P＜0.05),而右房内径、右室横径及主动脉内径差异无统计学意义(P＞0.05),另2例妇女产后INIDd、LVIDs仍增高但LVEF减低;对照组与产后组之间各指标差异无统计学意义(P＞0.05).结论 妇女妊娠期LVIDd、INIDs及肺动脉内径增加,心脏收缩功能增强,A/E比值增加,PASP增高,大部分心脏结构和功能的变化为生理性可逆过程.     

Angiographic long-term follow-up of primary apical ballooning of the left ventricle

Acute and reversible left ventricular apical wall motion abnormalities presenting with chest pain, electrocardiographic (EKG) changes and cardiac markers release, in the absence of coronary artery stenosis, have already been identified as a possible distinct clinical entity: the so-called Tako-Tsubo syndrome. A 65-year-old man with history of hypertension, hypercholesterolemia and smoking, was admitted at the emergency room of a secondary referral institution with a severe and prolonged (45 min) chest pain, irradiated to the left arm, associated with neurovegetative syndrome. The clinical presentation suggested an acute myocardial infarction (AMI). Interestingly no coronary artery stenoses or vasospasm reaction to administration of acetylcholine could be detected. A slow flow phenomenon was present. The left ventricle angiography confirmed a mild depression of left ventricle systolic function (EF 45%), with akinesia of antero-lateral wall and the typical apical ballooning-like profile. At 3-month follow-up, the patient continued to be asymptomatic and the echocardiogram showed a progressive normalization of left ventricle segmental motion and ejection fraction with a complete restoration only after 6 months. At 1 year the coronary angiography confirmed the absence of coronary stenosis, with complete regression of the ventricular apical ballooning at left ventricle catheterization. At two-year follow-up the patient is still asymptomatic. A slow resolution of the syndrome should be included in the diagnostic criteria for apical ballooning.     

常规超声心动图结合自动室壁分区运动分析和全方位M型超声心动图技术评价冠状动脉支架置入术后心脏整体功能

目的 应用常规超声心动图结合自动室壁分区运动分析（ASMA）及全方位M型超声心动图（FAM）技术对冠状动脉支架置入术后心脏整体功能改善情况进行评估。方法冠心病心肌缺血需行冠状动脉支架置入术患者21例。术前、术后24h及1周分别应用常规超声心动图结合ASMA及FAM采集心脏形态学和心功能指标。结果 冠状动脉支架置入术后，随着缺血部位心肌血供明显改善及左室重构逆转，心脏形态学、室壁运动状态及心功能等参数测值均明显改善（P〈0．01），1周后基本趋于稳定。结论 冠状动脉支架置入术后能够明显改善冠心病患者室壁运动及心脏整体功能状况；ASMA—FAM技术定量评价室壁运动状态的敏感性及特异性较高。     

正常胎儿超声心动图研究

[目的]利用超声心动图研究正常胎儿在妊娠期间的心功能变化[方法]应用Acuson　128XP/10超声诊断系统测定120例正常胎儿(按孕周分为六个组:16-20周;20+1-24周;24+1-28周;28+1-32周;32+1-36周;36+1-40周)的各项心功能参数:主动脉、肺动脉的峰值血流速度(PFV),每搏输出量(SV),心输出量(CO),心室射血力(F),左、右心室的短轴缩短率(FS)和射血分数(EF)。[结果]①主、肺动脉PFV、SV、CO、F随孕周增加而增加,与孕周呈直线相关(P<0,05);②左、右室FS和EF不随孕周增加而增加,在整个妊娠期保持相对恒定(P>0.05);③主动脉PFV大于肺动脉(P<0.05);左心室SV、CO小于右心室(P<0.05);左心室F、FS、EF与右心室相似(P>0.05)。[结论]①正常胎儿具有相对健全的泵功能,且右心功能占优势。②超声心动图是检测胎儿心功能的一种可行和可靠的无创性研究手段。     

Emergency guide wire pacing: new methods for rapid conversion of a cardiac catheter into a pacemaker

We developed a new electrode to convert rapidly a previously inserted pulmonary artery or left ventricular catheter into a pacemaker. One method of doing this is by withdrawal of the pulmonary artery catheter from the pulmonary artery to the right ventricle by pressure control, and a Teflon-coated guide wire, stripped of 5 mm of insulation at its tip, is advanced through the catheter to contact the endocardium. In the second method, the pacing electrode is advanced through the distal lumen of the catheter while it is positioned within the pulmonary artery and withdrawn into the right ventricle while pacing. Finally, a third Method involves advancement of the guide wire electrode into the left ventricle through a pigtail catheter. To pace, the guide wire electrode is connected to the cathode of a pacemaker referenced to a skin electrode. We paced 10 of 10 right heart cardiac catheterization, intra- and postoperative surgery patients by methods 1 and 2, and 4 of 4 left heart catheterization patients by method 3. Thresholds (mean ± SEM) for guide wire pacing were: right ventricle 1.52 ± 0.4 mA; left ventricle 1.33 ± 0.1 mA. Guide wire pacing is rapid, reliable, and requires little operator skill. Our indications for guide wire pacing are: 1) emergency right ventricular pacing in operative or intensive care unit patients with unexpected bradyarrhythmias who have an indwelling pulmonary artery catheter; and 2) emergency left ventricular pacing in left heart cardiac catheterization patients with contrast-induced bradyarrhythmias.     

Increased rat cardiac angiotensin converting enzyme activity and mRNA expression in pressure overload left ventricular hypertrophy. Effects on coronary resistance, contractility, and relaxation.

We compared the activity and physiologic effects of cardiac angiotensin converting enzyme (ACE) using isovolumic hearts from male Wistar rats with left ventricular hypertrophy due to chronic experimental aortic stenosis and from control rats. In response to the infusion of 3.5 X 10(-8) M angiotensin I in the isolated buffer perfused beating hearts, the intracardiac fractional conversion to angiotensin II was higher in the hypertrophied hearts compared with the controls (17.3 +/- 4.1% vs 6.8 +/- 1.3%, P less than 0.01). ACE activity was also significantly increased in the free wall, septum, and apex of the hypertrophied left ventricle, whereas ACE activity from the nonhypertrophied right ventricle of the aortic stenosis rats was not different from that of the control rats. Northern blot analyses of poly(A)+ purified RNA demonstrated the expression of ACE mRNA, which was increased fourfold in left ventricular tissue obtained from the hearts with left ventricular hypertrophy compared with the controls. In both groups, the intracardiac conversion of angiotensin I to angiotensin II caused a comparable dose-dependent increase in coronary resistance. In the control hearts, angiotensin II activation had no significant effect on systolic or diastolic function; however, it was associated with a dose-dependent depression of left ventricular diastolic relaxation in the hypertrophied hearts. These novel observations suggest that cardiac ACE is induced in hearts with left ventricular hypertrophy, and that the resultant intracardiac activation of angiotensin II may have differential effects on myocardial relaxation in hypertrophied hearts relative to controls.     

Hyperplasia of myocyte nuclei in long-term cardiac hypertrophy in rats.

In contrast to observations made in the human heart, hyperplasia of myocyte nuclei has never been demonstrated in experimental cardiac hypertrophy. To test the hypothesis that the duration of the mechanical load more than the magnitude of ventricular hypertrophy may be the inciting stimulus for myocyte nuclei hyperplasia, constriction of the pulmonary artery was produced in rats and the hearts were examined 6 mo later. A 76% increase in right ventricular weight was measured. This hypertrophic response was accompanied by a 41% increase in the total number of myocyte nuclei in the ventricle. Furthermore, average myocyte cell volume per nucleus increased by 28%. No changes in weight, myocyte size, and nuclear number were observed in the left ventricle. In conclusion, myocyte nuclear hyperplasia and cellular hypertrophy both participate to the adaptive response of the right ventricular myocardium in long-standing pressure overload cardiac hypertrophy.     

成人冠状动脉瘘的CT血管成像特点

目的 探讨冠状动脉瘘(CAF)的CT血管成像特征。方法 分析45例接受DSCT (31例)及256 iCT(14例)成像CAF患者的图像质量、辐射剂量及影像学特征。结果 45例CAF患者的CTCA图像质量均满足诊断需要,平均有效剂量为(12.92±3.73)mSv。CAF起自左冠状动脉23例、右冠状动脉13例、起自两者7例,起自右冠状动脉及支气管动脉1例,起自右冠状动脉及头臂干1例。CAF单一瘘管33例,多发瘘管12例。瘘入右心系统共40例,其中瘘入肺动脉31例、冠状窦4例、右心房3例、右心室1例、上腔静脉1例;瘘入左心系统5例,其中瘘入左心房2例、左心室2例、肺静脉1例。瘘血管可有纡曲、血管丛样、扩张或动脉瘤形成等表现。结论 CTCA检查可无创、准确地显示CAF的部位、走行及并发畸形,可作为临床诊断CAF的首选检查方法。