Effects of mercury on the contractile activity of the right ventricular myocardium

The increase in right ventricular systolic pressure observed in vivo after the administration of mercury opposes to the idea that the metal depresses the cardiac pump performance. We then investigated the effects of HgCl₂ (0.1 to 2.5 μM) on the contractile activity of the right ventricular myocardium, measuring isometric and tetanic contractions of right ventricular isolated strips, right ventricular isovolumic systolic and diastolic pressures, and the coronary perfusion pressure (0.03 to 3 μM) in constant-flow Langendorff-perfused rat hearts. The results presented here suggest that the acute effects of mercury on the right ventricular myocardium are distinct. When isolated strips of right ventricular wall are used, the contractile depression produced by mercury is manifested. However, when mercury is administered to isolated perfused hearts or in vivo this depressant effect is not revealed. The possible reasons for this behavior are the increased coronary perfusion pressure, which promotes a positive inotropic effect, manifested during the infusion of increasing concentrations of mercury, or the putative stretch of the ventricular fibers, which might cause the increment of diastolic pressure. An interesting finding is that the mechanical activity of the preparations, in which mercury is administered via coronary circulation, is not depressed and, even more, it can increase systolic pressure. However, the nature of this protective effect of coronary circulation cannot be explained by the results presented here. Received: 6 November 2000/Accepted: 27 April 2001     

Effect of pulseless ventricular tachycardia on sympathetic activity

The role of sympathetic activation in the genesis of life threatening ventricular arrhythmia is abundantly documented. The protective effect of sympathetic activation at the time of destabilizing ventricular tachycardia is less well known. Recently, muscle sympathetic nerve activity was recorded at our cardiac electrophysiology laboratory in a 62-year-old man who suffered from severe left ventricular failure. In order to elucidate the complex relationship between arrhythmias and autonomic nervous activity, his muscle sympathetic nerve activity recording depicting response to pulseless ventricular tachycardia is hereby presented.     

Absence of antiarrhythmic effects of helium in patients with spontaneous premature ventricular beats at rest

Six patients with spontaneously occurring arrhythmias were studied to assess the antiarrhythmic properties of helium. The patients were divided into two subgroups breathing air, helium-oxygen (heliox), and nitrogen-oxygen (nitrox) in an alternating sequence during successive 20-min periods under continuous ECG surveillance at rest. There were no significant reductions in spontaneously occurring premature ventricular beats while breathing heliox, compared to breathing air of nitrox. Alternating the breathing gases in this manner caused no change in plasma concentration of electrolytes or in activity of serum glutamic-oxaloacetic transaminase or lactic acid dehydrogenase. We conclude that helium does not affect spontaneously occurring chronic premature ventricular beats in conscious resting man when it is breathed for a period of up to 20 min.     

Interplay among cardiac chambers. Left and right ventricular performance during changes in contractility, afterload and during simultaneous atrio-ventricular contraction

1. Only a slight increase in stroke volume is observed during a selective left-sided inotropic stimulation of the in situ pig heart. Decreased left ventricular preload during left-sided inotropic stimulation reduces activation of the Frank-Starling mechanism and hence explains the rather small increase in stroke volume. We suggest that left-sided inotropic stimulation redistributes blood from the pulmonary circulation toward the systemic circulation causing a fall in pulmonary artery pressure and increased right ventricular output because of this afterload-reduction. 2. A rise in stroke volume during selective right-sided inotropic stimulation is not attenuated by a concomitant reduction in right ventricular preload. On the contrary, right ventricular preload rises in response to inotropic stimulation of the right atrium. Right-sided inotropic stimulation redistributes blood toward the pulmonary vascular bed and the left side of the heart. Left ventricular function is improved by this redistribution. 3. Both left ventricular end-systolic and end-diastolic volumes are better maintained by thoracic aortic occlusion during left-sided inotropic stimulation than at control inotropy. The concomitantly better preserved dimensions in the right ventricle can be explained by reduced pressure in the pulmonary circulation and a decrease in right-ward septal bulging. The rise in stroke volume by aortic occlusion during intravenous isoproterenol infusion is mainly due to a greater redistribution volume than at control inotropy. 4. Prolongation of the diastolic interval may reduce the end-diastolic pulmonary artery pressure to such an extent that right atrial contraction could eject blood into the pulmonary artery during late ventricular diastole.(ABSTRACT TRUNCATED AT 250 WORDS)     

Left ventricular systolic and diastolic function and dysfunction

The left ventricular systolic function--independently from the type of cardiac disease--determines the quality of life and the prognosis of the patients, so the examination of this parameter is indispensable. To measure it accurately is difficult, because the muscle fibers in the ventricular wall run partly circumferentially, partly longitudinally and tangentially and we have not any kind of method, which could have examined the function all of these differently contracting myocardial muscle fibers. To add these, the shape of the left ventricle is geometrically irregular, all ventricular segments move toward a "gravitational point" during the systole and backward during the diastole, and the heart also has a rotational motion in the chest during every cardiac cycle. Haemodynamic parameters (preload, afterload, heart rate and synchronous or asynchronous motion of the left ventricular walls) also can modify the left ventricular function. The ejection fraction is most frequently measured by echocardiography. M-mode, 2-dimensional, 3-dimensional echocardiography, Doppler methods, Doppler Myocardial Imaging (DMI), contrast echocardiography and color kinesis can be used to get more precise information about the left ventricular systolic function. The diastolic left ventricular function can be analysed using the mitral Doppler curve. The DMI, Strain Rate Imaging (SRI), contrast echocardiography and color kinesis improve the quality of imaging and so the accuracy of measurement. Using Doppler Myocardial Imaging and Strain Rate Imaging we can get information about the global and segmental left ventricular systolic and diastolic function. These parameters are well reproducible, and that is why they can be used in the assessment of the efficacy of pharmaceutical or other therapeutical procedures and following the changes in the clinical state of the patients.     

Amidaron-induced dermatopathy resulting from unnecessary Cordarone therapy of ventricular parasystole]

The case history of a patient is reported who was treated with a variety of antiarrhythmics over a period of years because of refractory ventricular "bigeminy". As the arrhythmia did not respond to any kind of therapy, amiodarone treatment was started, which the patient received in a maintenance dose of 600-400 mg/day for 4 years. More recently, a bluish-grey hyperpigmentation of the face and other areas of the skin exposed to sunlight developed. A cutaneous biopsy of the hand revealed pigment deposits and lamellated lysosomal inclusions characteristic for amiodarone dermatopathy. The interactive, computer-assisted analysis of the ventricular ectopic activity has clearly demonstrated its innocent, parasystolic nature. The differentiation between ventricular extrasystolic and parasystolic activity is essential, because the latter arrhythmia does not require specific antiarrhythmic pharmacotherapy.     

History and current trends in sudden cardiac arrest and resuscitation in adults

Cardiac arrest occurs when organized cardiac contractility ceases and circulation stops. During cardiac arrest, electrical activity may be abnormal or absent, and the rhythm documented can be ventricular fibrillation, pulseless ventricular tachycardia, pulseless electrical activity, or asystole. It has been estimated that 300 000 sudden cardiac arrests occur each year in the United States, with 75% (225,000) occurring out-of-hospital and 25% (75,000) occurring in-hospital. A similar number occur in Europe each year. The 3-phase model of cardiac arrest, which proposes that a cardiac arrest progresses through distinct phases as time elapses, helps inform research and clinical care by providing a framework for improving outcomes from cardiac arrest. Early in an arrest, during the electrical phase, defibrillation is paramount. The circulatory phase begins after 4 to 5 minutes, and interventions to optimize circulation become of primary importance. When an arrest is prolonged, lasting for ≥10 minutes, the patient passes into the metabolic phase, in which significant metabolic derangements have accrued and start to dominate arrest physiology. If return of spontaneous circulation occurs during this phase, significant injury to diverse organs may have occurred, producing a critical illness known as post-cardiac arrest syndrome. The post-cardiac arrest syndrome has been recognized as a unique entity requiring unique therapies for successful management. Recent advances in cardiac arrest care include cardiocerebral resuscitation and the use of therapeutic hypothermia to treat comatose survivors of cardiac arrest.     

Bicarb Corrects Growth Defect in Renal Tubular Acidosis

Abstract

Cardiac arrest occurs when organized cardiac contractility ceases and circulation stops. During cardiac arrest, electrical activity may be abnormal or absent, and the rhythm documented can be ventricular fibrillation, pulseless ventricular tachycardia, pulseless electrical activity, or asystole. It has been estimated that 300 000 sudden cardiac arrests occur each year in the United States, with 75% (225 000) occurring out-of-hospital and 25% (75 000) occurring in-hospital. A similar number occur in Europe each year. The 3-phase model of cardiac arrest, which proposes that a cardiac arrest progresses through distinct phases as time elapses, helps inform research and clinical care by providing a framework for improving outcomes from cardiac arrest. Early in an arrest, during the electrical phase, defibrillation is paramount. The circulatory phase begins after 4 to 5 minutes, and interventions to optimize circulation become of primary importance. When an arrest is prolonged, lasting for ≥ 10 minutes, the patient passes into the metabolic phase, in which significant metabolic derangements have accrued and start to dominate arrest physiology. If return of spontaneous circulation occurs during this phase, significant injury to diverse organs may have occurred, producing a critical illness known as post-cardiac arrest syndrome. The post-cardiac arrest syndrome has been recognized as a unique entity requiring unique therapies for successful management. Recent advances in cardiac arrest care include cardiocerebral resuscitation and the use of therapeutic hypothermia to treat comatose survivors of cardiac arrest.     

七氟醚与氯胺酮应用于室间隔缺损患儿麻醉诱导的对比研究

目的:观察七氟醚与氯胺酮应用于室间隔缺损患儿麻醉诱导时的差异,以求找到更适合室间隔缺损患儿的诱导方法。方法:40例行室间隔修补术的3~6岁患儿,ASAⅠ~Ⅱ级,无神经系统及精神疾患,随机分为A、B两组,每组20例。A组诱导采用肌注氯胺酮6~8mg·kg-1,阿托品0.01~0.015mg·kg-1,待患儿意识消失后开放静脉,给予咪唑安定1mg,芬太尼10μg·kg-1,万可松0.8~1.0mg·kg-1,地塞米松2mg,气管插管。B组诱导采用面罩吸入七氟醚,待睫毛反射消失后开放静脉,给予芬太尼10μg·kg-1,万可松0.8~1.0mg·kg-1,地塞米松2mg,气管插管。记录各组患儿诱导时间,诱导时的顺从性评分、血流动力学变化及副反应,诱导后分泌物情况。结果:B组患儿的诱导顺从性评分、诱导时间及诱导后患儿分泌物重量B组均明显小于A组,P<0.01。A组患儿诱导后血压、心率显著升高(P<0.01)。B组患儿诱导后血压无明显变化(P>0.05);心率显著减慢(P<0.05)。B组患儿诱导后血压、心率均显著低于A组(P<0.01)。A组有2例患儿诱导时缺氧发作,B组患儿未见任何副反应发生。结论:对于室间隔缺损患儿,吸入七氟醚麻醉诱导明显优于肌注氯胺酮。     

Fatal Left Ventricular Aneurysm in a 13 Years Old Male Child: A Case Report

BackgroundA pouch protruding from the free wall of the left ventricle may be either a congenital ventricular diverticulum or congenital ventricular aneurysm. Congenital ventricular aneurism is a ventricular protuberance which is a kinetic or dyskinetic and on histology is predominantly fibrous tissue with no organized myocardium. Common clinical presentations of congenital ventricular aneurism are arrhythmia, rupture and heart failure.Case DetailA 13 year old patient presented with shortness of breath, fever, orthopnea of two pillows and paroxysmal nocturnal dyspnea of one week duration. Echocardiography revealed cystic mass seen at the apex of the heart communicating with left ventricle, with communicating defect and flow on color Doppler study. CT scan showed ventricular aneurism at the apex. The patient was managed for heart failure and passed away after few hours'' of establishing diagnosis.ConclusionCongenital ventricular aneurysm is a rare condition which needs careful diagnosis for subsequent management.     

Aortic endocarditis complicated with a large ventricular septal defect and septic pulmonary embolism

BACKGROUND: Infectious complications of the aortic valve can lead to severe cardiac failure and widespread contiguous lesions by the involvement of subaortic structures such as aorto-left ventricular discontinuity, destruction of the aortic ring, aortic abscesses, true or false aneurysms and shunts. AIM: Report a new case of a large ventricular septal defect due to infection. CASE REPORT: Abnormal communications occurring during acute aortic valve endocarditis are rare but they are very serious complications. We report a case of a 58 year-old-man, referred to our hospital with the diagnosis of aortic endocarditis with complicating root abscesses, acquired ventricular septal defect (VSD) and pulmonary septic embolism. Surgery was indicated and the whole procedure was performed through the aortic root. The patient underwent a radical resection of the abscesses, reconstruction of the aortic ring, closure of the ventricular septal defect and prosthetic replacement of the aortic valve. The immediate postoperative course was marked by persistent sepsis. Transoesophageal echocardiography showed vegetation's in the right side of the patch without signs of dehiscence. The outcome was fatal due to hemodynamic collapse. CONCLUSION: The authors would like to select and analyze some weaknesses of their procedure like using only the transaortic access that often limits exposure of possible right-side lesions, not removing the pulmonary obstruction and using an important amount of foreign material to reconstruct subvalvular lesions.     

Natural history of chronic left ventricular aneurysm; a population based cohort study

In order to evaluate the morbidity and mortality of chronic left ventricular aneurysm a population based cohort study was carried out. All cardiac catheterizations performed in Iceland during the years 1983-1985 were examined (n = 1261). Sixty seven patients with left ventricular aneurysm defined as: (1) normal diastolic contour with segmental dyskinesis (n = 6), (2) abnormal diastolic contour with (a) akinetic (n = 36) or (b) dyskinetic (n = 25) segments in systole, were included. Sixty seven patients with normal diastolic contour and akinetic segments in systole served as controls. The groups had similar mean age, sex ratio, number of diseased vessels and left ventricular end diastolic pressure. Mean ejection fraction was significantly lower in the aneurysm group (46 vs 56%, p = 0.00005). Collaterals were detected significantly more often in controls (88 vs 72%, p = 0.03). At follow up in 1989, 19 in the aneurysm group had died as compared to 12 in the control group. Life table analysis revealed significant differences between survival curves. The relative risk ratio was 2.18 with 95% confidence interval of 1.00-4.74 (p less than 0.05). However, when the amount of myocardial damage was taken into account the differences in survival were no longer statistically significant (relative risk ratio 1.77 with 95% confidence interval of 0.79-3.99). We conclude that the reduced survival probability of patients with chronic left ventricular aneurysm in comparison to controls with akinetic scars is accounted for by the more extensive myocardial damage and not by the presence of aneurysm per se.     

右室多部位起搏的QRS宽度与心功能的对比研究

目的 比较右室心尖部（RVA）、右室流出道（RVOT）和右室双部位（RV—Bi）起搏的ORS宽度和对心功能的影响。方法 8例患者分别于术中行RVA、RVOT及RV—Bi起搏，在同一起搏频率下测定每搏量（SV）、射血分数（EF）、心输出量（CO）、QRS宽度（QRSa）和电轴（QRSa）。结果 与RVA起搏相比，RVOT和RV—Bi起搏的EF、SV和CO均增加，以RV—Bi增加明显（P〈0．01）；RV—Bi和RVOT起搏较RVA起搏的QRSd分别缩短43ms和17ms，而RV—Bi则比RVOT缩短26ms，差异均有统计学意义（P〈0．05或P〈0．01）。结论 比较三种起搏方式，RV—Bi起搏的QRSd最窄，心功能最优，RVOT起搏次之，RVA起搏最差。     

超声对胎儿单纯室间隔缺损在宫内和产后婴儿期闭合情况的研究

目的应用超声心动图观察胎儿期及产后婴儿期单纯室间隔缺损（IVSD）自然愈合的情况及影响因素。方法选取61例诊断有胎儿单纯性室缺但不愿终止妊娠的孕妇为研究对象,对胎儿进行二维和彩色多普勒超声心动图检查,记录胎儿室间隔缺损的位置、形态、大小、自然闭合的时间和闭合率,出生后存活的婴儿监测室间隔缺损（VSD）上述指标至1岁,计算宫内及产后1年的闭合率及总的闭合率、不同位置室缺的闭合率,并对不同大小室缺的闭合率进行组间比较。结果在61例中,22例（36.1%）宫内自然闭合,9例（14.8%）在产后1年内闭合,30例（49.2%）仍未闭合。室间隔缺损的大小以及缺损的位置与愈合率有关,室间隔缺小于3.0mm的闭合率明显高于室缺为3.1~5.0mm的闭合率（P=0.005）和5mm以上室缺的闭合率（P=0.002）,但室缺为3.1~5.0mm的闭合率与大于5mm的室缺的闭合率之间无显著性差异（P=0.39）。膜部和肌部缺损的闭合率明显高于干下型室缺的闭合率（P≤0.01）,肌部缺损的闭合率高于膜部缺损的闭合率,但两者之间无统计学差异（P=0.65）。结论单纯室间隔缺损有较高的宫内自然闭合率并且在产后婴儿期仍能自然闭合,这种自然愈合的过程与室间隔缺损的位置和大小显著相关。肌部和膜部缺损最容易愈合,干下型不易闭合;小缺损具较高的闭合率,较大的缺损不易闭合。     

射频消融治疗室性心律失常的疗效

目的观察室性心律失常射频消融治疗的效果。方法18例室性心律失常患者,其中9例为右心室流出道室早,4例为左心室间隔部室早,5例为左心室特发性室速。分别采用起搏标测或起搏与激动顺序标测结合的方法进行标测消融。结果消融失败2例,好转1例,成功15例,成功率为83.3%,总有效率为88.9%。结论射频消融治疗室性心律失常是一种安全有效的方法。     

Review of dilated cardiomyopathies. Dilated cardiomyopathies and altered prothrombotic state: a point of view of the literature

Heart failure is an enormously important clinical problem that, if not faced, may overwhelm health care resources. Primary and secondary cardiomyopathies cause the majority of cases of clinical heart failure, which is thus better approached from the utility point of view of myocardial failure. Furthermore, the risk of thromboembolic complications presenting in such disease may be higher than in ischemic cardiomyopathy. Intracardiac thrombi and mural endocardial plaques (from the organization of thrombi) are present at necropsy in more than 50% of patients with dilated cardiomyopathy (DCM). Several studies have shown that systemic and pulmonary emboli are more frequent in patients with ventricular thrombi or plaques. Dilated cardiomyopathy has been associated with left ventricular thrombosis which leads to substantial morbidity and mortality as a site for peripheral emboli. There are some studies on patients with dilated cardiomyopathy showing altered hemostasis and platelet behavior despite sinus rhythm. Platelet activation, thrombin activation and fibrinolytic activity are increased in patients with DCM compared to normal subjects. However, these markers reflecting coagulation activation in patients with left ventricle thrombus are comparable to those in patients without thrombus in the left ventricle. The pathophysiology and clinical issues concerning the susceptibility to develop left ventricular (LV) thrombosis and its complications like cerebrovascular disease in patients with DCM are summarized and the most recent articles present in the medical literature are reviewed.     

Chronically increased activity of the sympathetic nervous system: Our diet-related “evolutionary” inheritance

Objective  It is well established that an increased activity of the sympathetic nervous system (SNS) plays an important role in the pathogenesis of cardiovascular disease (CVD), like essential hypertension, atherosclerosis and age related arterial wall thickening, heart failure, and ventricular arrhythmias. It is also well established that SNS activity is influenced by food ingestion, and that diet composition plays an important role: Among dietary substrates, carbohydrate (starch and sugars) ingestion significantly increases SNS activity, while protein or fat ingestion has no significant sympathoexcitory effect. The aim of this paper is to investigate the possibility that significant dietary changes during human evolution, i. e. the introduction of starch and sugars into human nutrition, have brought about a deleterious effect: an abnormal, chronically increased activity of the sympathetic nervous system (SNS). Method  Literature search using MEDLINE to identify publications on the relationship of SNS activity and cardiovascular disease on the one hand and dietary substrates on the other hand. Conclusion  The introduction of starchy food and sugars has brought about a new metabolic problem: a diet-related chronically increased SNS activity, with adverse effect on human health.     

Life-threatening ventricular tachycardia during flecainide treatment for symptomatic atrial fibrillation in a patient with a structural cardiac disorder

A 37-year-old man with symptomatic acute atrial fibrillation and a low-voltage electrocardiogram was treated with flecainide intravenously. Instead of conversion to sinus rhythm, he developed a wide-complex tachycardia suggestive of ventricular tachycardia. The patient recovered following electric cardioversion. First-choice therapy for symptomatic atrial fibrillation of recent onset (duration < 48 hours) is chemical conversion with a class IC antiarrhythmic drug (e.g. flecainide, propafenone). However, in patients with structural heart disorders, these drugs may induce ventricular tachycardia. A low-voltage electrocardiogram is suggestive of left ventricular damage. For these patients, electric cardioversion is a better alternative.     

Percutaneous insertion of a left ventricular assist device for cardiogenic shock in a patient with a myocardial infarction

A 54-year-old man who was admitted due to cardiogenic shock as a result of a large anterior myocardial infarction 3 days previously was about to die, despite reperfusion therapy, application of an intra-aortic balloon pump, mechanical ventilation and maximal medical therapy. After insertion of a percutaneous left ventricular assist device, the patient was haemodynamically stable. After 11 days, the assist device was weaned and was removed. One day later, the patient died due to progressive heart failure. This case shows that a percutaneously inserted left ventricular assist device is effective in patients with severe, refractory cardiogenic shock, and is relatively simple to insert in the heart catheterisation room. However, it is still not clear what the recovery possibilities of the heart are following a large myocardial infraction, which factors may influence this recovery, and what the applicability of such a ventricular assist device might be in bridging the recovery period.     

Incidence of arrhythmia with central venous catheter insertion and exchange

The risk of complication during the insertion or exchange of central venous catheters has been well documented. The majority of complications involve mechanical problems associated with insertion. Although cardiac arrhythmia has been acknowledged as a possible complication, its incidence has never been quantified. We performed cardiac monitoring on patients during 51 central venous catheter insertions or exchanges to determine the incidence of cardiac arrhythmias during guidewire insertion. Forty-one percent of procedures resulted in atrial arrhythmias and 25% produced some degree of ventricular ectopy, 30% of these were ventricular couplets or greater. Ventricular ectopy was significantly more common in shorter patients (160 +/- 8 vs 168 +/- 11 cm, p less than 0.05) and when the catheter was inserted from the right subclavian position (43% ventricular ectopy vs 10% at the other sites). Other variables such as age, cardiac history, serum potassium, type of procedure, and catheter brand were not significant. It is our conclusion that over-insertion of the wire causes this cardiac stimulation. Despite the absence of morbidity or mortality in this study, this incidence of ventricular ectopy indicates that there is a distinct possibility of a malignant arrhythmia being precipitated by a guidewire. Some modification of the current protocol for these procedures seems indicated.