Long-term outcome of operative treatment of focal atrial tachycardia

BACKGROUND

This study examined the long-term clinical outcome of patients with focal atrial tachycardia who were treated surgically. Focal atrial tachycardia is a relatively rare arrhythmia that is often difficult to control with conventional medical therapy. Therapeutic modalities are not well defined because of the scarcity of long-term data of treated patients, including pathologic findings.

STUDY DESIGN

Nine patients, six men and three women, ranging in age from 16 to 50 years (mean of 34 +/- 14 years), underwent operative treatment for focal atrial tachycardia. The average rate of tachycardia was 167 +/- 22 beats per minute. All patients were treated with antiarrhythmic drugs (mean 2.9 drugs per patient). Concomitant operative procedures were performed upon four patients, including division of the accessory atrioventricular pathway for the Wolff-Parkinson-White syndrome in two patients, plication of the right atrium for idiopathic right atrial dilatation in one patient, and a closure of the atrial septal defect in one patient. Focal ablation was performed in all instances.

RESULTS

There was no early or late death nor postoperative complications. Atrial tachycardia disappeared and there were no episodes of recurrent tachycardia postoperatively during the mean follow-up period of 67 +/- 38 months. Histopathologic findings from four patients revealed a sinus node-like structure, diffuse chronic epimyocarditis, focal myocarditis, and fascicular disarray lesions.

CONCLUSIONS

Excellent long-term result were obtained in patients with focal atrial tachycardia who were treated operatively. Early operative intervention is preferable before the occurrence of impaired ventricular function. From the histopathologic findings, operative therapy should be selected in patients with diffuse atrial lesions.

Corticosteroid therapy for ventricular tachycardia in children with silent lymphocytic myocarditis

OBJECTIVE

The objective of our study was to describe the efficacy of corticosteroids for ventricular tachycardia in four children with structurally normal hearts in whom endomyocardial biopsy revealed histologic changes of lymphocytic myocarditis.

PATIENTS

The four patients had unexplained ventricular tachycardia. Three dysrhythmias were sustained, and one was inducible by exercise. Patient ages ranged from 4 months to 12 years. Three of the four patients had no symptoms. In two of them, ventricular tachycardia was identified by mass screening for heart disease. Two patients received oral steroids and two received pulse steroid therapy.

RESULTS

In all four patients, significant underlying diseases were not found by noninvasive evaluation. Right ventricular endomyocardial biopsy revealed abnormal histologic findings of chronic lymphocytic myocarditis in all patients. Steroid therapy was effective in all four patients, two of whom received methylprednisolone pulse therapy.

CONCLUSIONS

We conclude that unexplained ventricular tachycardia may be the only manifestation of clinically silent myocarditis. Steroid therapy should therefore be considered if conventional antiarrhythmic medication is not effective and histologic findings confirm the presence of lymphocytic myocarditis.

Causal association between major histocompatibility complex and myocardial infarction in NZW x BXSB F1 mice

The NZW x BXSB F1 male mice that a model for systemic lupus erythematosus (SLE) develop myocardial infarction. To determine whether the gene(s) linked to the major histocompatibility complex (MHC) of NZW mice are involved in myocardial infarction, we developed an H-2-congenic NZW.H-2d strain and compared the incidence of myocardial infarction in NZW x BXSB F1 (H-2z/b) male mice to that in NZW. H-2d x BXSB F1 male mice (H-2d/b). H-2z/b heterozygous F1 male mice showed a higher incidence of myocardial infarction than H-2d/b F1 male mice. This observation suggests that the myocardial infarction seen in SLE may be related to MHC.

Spontaneous non-traumatic rupture of the thoracic aorta

Spontaneous non-traumatic rupture of the aorta is a very rare condition that requires immediate surgery. However, correct preoperative diagnosis is difficult or impossible to establish. We report a case of spontaneous aortic rupture which was successfully treated by emergency surgical exploration following a transesophageal echographic diagnosis of hemopericardium. This case, as well as other reports, suggests that hemopericardium along with symptoms which suggest aortic dissection or rupture (e.g., acute chest or back pain) should raise a strong suspicion of spontaneous aortic rupture even in the absence of intimal flap or aortic dilatation, and the emergency surgery may be life-saving.

Apoptosis in acute and chronic myocarditis

Programmed cell death or apoptosis plays a major role in the modification of morphologic and functional maturity in various normal organ systems. However, it is also related to certain diseases. We conducted a pathological study of the apoptosis of cardiomyocytes in six cases with myocarditis (three of acute myocarditis and three of chronic or persistent myocarditis) using histochemical methods. In normal hearts obtained from autopsy cases, apoptosis was seen in endocardial cells. There was no apoptosis in myocardial cells, except for a few in myocytes with two nuclei. In myocarditis, although the myocytes of all cases with acute myocarditis did not show apoptosis, one of the three cases with chronic or persistent myocarditis showed many apoptotic myocytes. Apoptosis may be one of the mechanisms causing myocyte damage in myocarditis.

Antithrombin and thrombolytic effects of a new antithrombin agent: angioscopic and angiographic comparison with heparin or batroxobin

The antithrombotic effect of three different types of antithrombotic agents (antithrombin:argatroban, heparin, defibrinogenating agent:batroxobin) were evaluated in canine coronary and iliac arteries. An occlusive thrombus was produced by balloon injury. One of the three agents was infused intravenously at 1 hour after thrombus formation (heparin 250 U/kg, argatroban 0.5 mg/kg, batroxobin 0.5 U/kg) and the effect of thrombus size reduction was evaluated. On the contralateral side of the iliac artery, the preventive effect of these agents on thrombus formation was evaluated after balloon injury. In the iliac artery, angioscopic percent area obstruction by the thrombus before and 60 minutes after treatment reduced from 69% to 32% in the argatroban group, and from 64% to 51% in the batroxobin group (P < 0.0001 and P < 0.05, respectively). No significant change was observed in the heparin group. Angiography demonstrated the same trend. The percent area stenosis with thrombus at 60 minutes following balloon injury was 0.75% in the argatroban group, 18.9% in the heparin group (P < 0.05 vs argatroban), and 12.9% in the batroxobin group. Thrombus size at the treated site was smaller than that at the control site in all three groups (P < 0.05 vs control). In the coronary artery, angioscopic percent area obstruction by the thrombus before and 60 minutes after treatment reduced from 84% to 53% in the argatroban group, and from 86% to 68% in the batroxobin group (P < 0.0001 and P < 0.05, respectively). No significant change was observed in the heparin group. Angiography also demonstrated the same trend. The activated partial thromboplastin time (APTT) was prolonged to 189% of the control value with argatroban and to 1253% of the value with heparin (P < 0.0001). Fibrinogen was markedly reduced with batroxobin. These results showed that both the antithrombin agent and the defibrinogenating agent have a preventive effect on thrombus formation and the effect on thrombus size reduction, without marked prolongation of the APTT.

A case of arrhythmogenic right ventricular dysplasia with atrial flutter

A 57-year-old male who had arrhythmogenic right ventricular dysplasia (ARVD) with recurrent atrial flutter (AF) is reported. The patient had more frequent episodes of AF than of ventricular arrhythmias. Magnetic resonance imaging, echocardiography and right ventriculography revealed dilatation of the right ventricle and endomyocardial biopsy specimens from the right ventricle showed findings which were compatible with ARVD. The left ventricular specimen, however, also revealed a loss of myocytes and interstitial fibroelastic changes. The present case demonstrates an overlap of post-inflammatory or primary endomyocardial fibroelastic changes with ARVD.

Preventive effect of betamipron on nephrotoxicity and uptake of carbapenems in rabbit renal cortex

The preventive effect of betamipron (N-benzoyl-3-propionic acid: BP) on the renal uptake and nephrotoxicity of carbapenems (panipenem and imipenem) was studied in rabbits. Panipenem, a new carbapenem antibiotic, induced nephrotoxicity at a dose of 200 mg/kg, i.v., but this was less severe than that caused by a single dose of imipenem or cephaloridine. Along with the significant reduction of nephrotoxicity, the uptake of these carbapenems in the renal cortex was remarkably inhibited by simultaneous treatment with BP (200 mg/kg, i.v.). These results suggest that BP reduces the nephrotoxicity of carbapenems through inhibiting the active transport of carbapenems in the renal cortex. Because of the low toxicity of BP (LD50 in the rat, more than 3,000 mg/kg, i.v.), it was concluded that BP might be a good candidate for reducing the nephrotoxicity induced by panipenem or imipenem.

Surgical treatment of ventricular tachycardia after surgical repair of tetralogy of Fallot. Relation between intraoperative mapping and histological findings

BACKGROUND

The mechanism of ventricular tachycardia (VT) after correction of tetralogy of Fallot (TF) is poorly understood. The purpose of this study was to examine the histopathology of the arrhythmogenic area detected by intraoperative mapping.

METHODS AND RESULTS

The patients were three men who underwent radical surgery for TF at age 3, 3, or 5 years, respectively. VT developed at 8, 9, or 11 years, respectively, after surgery, and shock developed during VT in every case. The ECG revealed monomorphic VT in two cases and polymorphic VT in one case. Induction of VT resulted in a wide left-axis deviation-pattern QRS with cycle lengths varying between 260 and 330 milliseconds. The VT origin was identified at the right ventricular outflow tract (RVOT). A radical operation was performed with the patient under cardiopulmonary bypass. On epicardial mapping, delayed activation of the RVOT was recorded during sinus rhythm, and clockwise circus movement of the macroreentry current during VT on the right ventricular free wall was documented in each case. The VTs were treated successfully by surgical resection and cryoablation of the myocardium. In every patient, histology of the myocardial specimens showed degeneration, adiposis, fibrosis, inflammatory cell infiltration, and scattered myocyte islets. These lesions corresponded anatomically to the area of myocardium in which delayed activation was evident during epicardial mapping.

CONCLUSIONS

The results of this study indicate that patients with VT after radical correction of the TF have abnormal histopathological findings at the site of the prior right ventriculotomy scar. These lesions were noted within the region of delayed activation found during epicardial mapping and were found to be a part of the reentrant circuit.

Histopathological study of cardiac rupture following myocardial infarction with and without thrombolytic therapy

The characteristics of cardiac rupture associated with thrombolytic therapy for acute myocardial infarction (MI) were studied in the hearts of 10 autopsy patients, 7 men and 3 women aged 41-80 years (mean 59.9 +/- 13.2 years), who died of rupture of the free wall of the left ventricle following acute MI. The site of rupture was examined histologically and the percentage areas of living myocytes, the processes of organization, necrosis and degeneration, and hemorrhage were compared in four patients who received thrombolytic therapy (group R) and six patients without thrombolytic therapy (group N). There were four pathological findings at the site of rupture: necrosis, neutrophil infiltration, hemorrhage, and evidence of the process of absorption. Group R consisted of two patients with hemorrhage, one with absorption, and one with unsuccessful reperfusion and neutrophilic infiltration. Group N included three patients with necrosis, two with neutrophilic infiltration, and one with hemorrhage. The percentage area involved by necrosis and degeneration was significantly lower in group R than in group N. Therefore, local stress produced by more surviving myocardium around the smaller necrosis area and the weakness of myocardium due to hemorrhage and absorption may provoke cardiac rupture in acute MI patients receiving thrombolytic agent.

Mesothelioma in the atrioventricular node. Case report

A patient with complete atrioventricular block and an implanted permanent pacemaker died of colon cancer at the age of 64 years. At autopsy, a cardiac tumor in the region of the atrioventricular node (mesothelioma of the atrioventricular node) was found. The origin of this type of tumor is controversial. Histochemical findings suggested that the tumor in this case was of endodermal origin.

An autopsy case of hypertrophic cardiomyopathy with pathological findings suggesting chronic myocarditis

Myocardial fibrosis in patients with hypertrophic cardiomyopathy (HCM) may play an important role in the function and/or dimensions of the left ventricle. We present an autopsied case of HCM followed for 10 years. A 68-year-woman with HCM underwent trans-aortic myectomy of the interventricular septum in 1979. A significant amount of round cell infiltration, myocardial fibrosis and disarray were observed in the resected specimen. She experienced repeated admissions due to diabetes mellitus and congestive heart failure, and died of renal failure in 1989. An autopsy revealed extensive myocardial fibrosis and significant cell infiltration in the ventricular myocardium. The infiltrating cells were almost all lymphocytes, and the ratio of CD4 to CD8 was 3.8. This ratio was different from that of typical viral myocarditis. This case suggests that there may be an undefined inflammatory process causing fibrosis in HCM, in addition to the ischemia due to intramural small coronary artery stenosis.

Protective effect of N-acyl amino acids (NAAs) on cephaloridine (CER) nephrotoxicity in rabbits

The protective effect of N-acyl amino acids (NAAs) against cephaloridine (CER)-induced nephrotoxicity was studied in rabbits. A large single intravenous dose of CER (more than 100 mg/kg) induced severe proximal tubular necrosis. Simultaneous treatment with several NAAs (at dosages of 100, 200 mg/kg, etc., i.v.), such as N-benzoyl-beta-alanine (NBBA), N-benzoyl-6-aminocaproic acid, and N alpha,epsilon-dibenzoyl-D,L-lysine, remarkably suppressed the histopathological damage in the kidney induced by CER. NAAs have generally low toxicity in laboratory animals (e.g., the LD50 of NBBA was more than 3,000 mg/kg, i.v. in rats), and NAAs were suggested to be good candidates for reducing the nephrotoxicity of CER and other beta-lactam antibiotics.

Three-dimensional distribution of myocardial fibrosis in the new J-2-N cardiomyopathic hamster: comparison with electrocardiographic findings

Using the new J-2-N strain of cardiomyopathic hamster obtained by cross-breeding Bio 14.6 and Golden hamsters, we investigated the three-dimensional distribution of ventricular myocardial fibrosis and compared it with electrocardiographic (ECG) changes. Twelve-lead ECG recordings were made by our own method. The hearts were cut into serial sections and subjected to light microscopic examination. The distribution, density, and volume of myocardial interstitial fibrosis and replacement fibrosis due to myocardial degeneration (F%) were visualized three-dimensionally using the TRI system (TRI; Three-Dimensional Reconstruction Image; Ratoc System Engineering, Tokyo, Japan). Thirty-two J-2-N hamsters were divided into two groups; one group comprised 17 animals with normal hearts and normal ECG findings similar to those of Golden hamsters, and the other group of 15 hamsters had dilated hearts and abnormal ECG findings. In the normal hearts, the F% values for the right ventricle, left ventricle, and ventricular septum were 6.4 +/- 0.94, 6.5 +/- 0.95, and 6.5 +/- 0.98 (mean +/- SD), respectively. The dilated hearts showed marked fibrosis, which was distributed mainly in the middle layer of the left ventricle and the ventricular septum. The corresponding F% values for the hamsters with cardiac enlargement were 19 +/- 2.6, 19 +/- 1.8, and 22 +/- 3.2 (mean +/- SD), respectively. Replacement of myocytes by fibrosis seemed to correspond to abnormal Q waves in the anterior chest leads and left axis deviation of the QRS complex.

Mapping of replication initiation site in Mycoplasma capricolum genome by two-dimensional gel-electrophoretic analysis

The homolog of the dnaA gene, which has been reported to be present in the vicinity of the initiation site of replication in the genome of Mycoplasma capricolum (M.Miyata, L.Wang, and T.Fukumura, J. Bacteriol. 175: 655-660, 1993) was mapped precisely. A 9540-bp region containing the dnaA gene was cloned and the entire region was sequenced with the exception of a previously reported region of 2517 bp (Fujita, M.Q., Yoshikawa, H. and Ogasawara, N. Gene 93: 73-78, 1992). The organization of the 9540-bp region was compared with that of corresponding regions in other bacteria. The arrangement and directions of rnpA, rpmH, dnaA, dnaN were conserved, but no other open reading frames were found that were homologous to those that are commonly found around dnaA genes in other bacteria. The directions of movement of the replication fork around the dnaA gene were analyzed by neutral/alkaline two-dimensional gel electrophoresis. The forks developed in a 1569-bp region that consisted of the dnaA structural gene and its downstream non-coding region, and then they proceeded bidirectionally.

A case of idiopathic ventricular fibrillation with incomplete right bundle branch block and persistent ST segment elevation

We report the case of a 42-year-old male who suffered from ventricular fibrillation (VF) without obvious QT prolongation. His electrocardiogram showed incomplete right bundle branch block (IRBBB) and persistent ST segment elevation in the right precordial leads during sinus rhythm. Cardiac catheterization revealed no overt heart disease except moderate endocardial and subendocardial fibrosis in the left ventricle. Mental stress seemed to trigger VF, and ST elevation became prominent just before VF. Propranolol and mexiletine have been effective in preventing VF for over 3 years.

Morphological study on vagal innervation in human atrioventricular valves using histochemical method

To demonstrate innervation in human atrioventricular valves, we examined the tricuspid and mitral valves of apparently normal autopsied hearts of four men (ages ranging from 50 to 74 years). Whole valve tissues were stained for acetylcholinesterase by a histochemical method. Acetylcholinesterase-positive nerve fibers with a diameter of 2 to 5 microns were distributed widely in the deep atrialis of the atrioventricular valves and partly in the fibrosa. The nerve fibers formed a network or plexus from the base to the anatomical edge of the valves. Meshes of the nerve fiber network were more dense towards the base and at the commissure than either towards the edge or at the body. Thicker nerve fibers, which were interspersed coarsely in the leaflets, were intercalated by special varicose apparatuses at a few sites in their long running course. On the contrary, thinner nerve fibers which were distributed abundantly, ended, as a rule, in small dotor brush-like formations. Approximately half of the chordae tendineae were innervated by the nerve fibers. The mode of vagal innervation suggests that the nerve system may assist valve movement by moderating myocyte contraction in the valve base and change valve structure by sensing a stress in the valves.

[Autopsy results of an elderly case of Parkinson's disease and aorto-esophageal fistula who died of a massive hematemesis during prolonged bed rest]

An 81-year-old female patient with an 8-year history of Parkinson's disease was hospitalized because of aspiration pneumonia. The clinical course of her pneumonia was prolonged because of dysphagia with a short period of remission, and she required a long period of bed rest. She received supportive nutrition via a nasogastric tube and many peroral medications that consisted of 3 anti-Parkinsonian drugs and 5 anti-bacterial or anti-tussive agents. Six months after admission, she vomited fresh blood through the nasogastric tube, then went into hypovolemic shock. Hemodynamic stability was temporarily achieved by blood transfusion. Gastroduodenal endoscopic examination could not reveal the exact bleeding site because of massive blood clots. Five days later, the patient died of a massive hematemesis. Autopsy revealed 2 chronic longitudinal ulcers, each 1.7 x 0.4 cm in size, in the upper portion of the esophagus. One of them had developed a fistula to the aorta. Neither esophageal carcinoma nor a foreign body was detected around the fistula. Atherosclerosis of the aorta was mild and the perforation channel was covered with the esophageal epithelium. The fistula was assumed to be a product of local esophageal injury due to drug retention.

Loss of vasoreactivity by laser thermal energy or argon laser irradiation

Vasoreactivity of laser-treated vessels was investigated in two different experimental conditions. The canine left circumflex coronary artery (LCx) was lased under perfusion with Krebs-bicarbonate buffer by means of a thermal laser (hot-tip probe, HT) at 7 W for 6 seconds and an argon laser beam through a 300 microns optical fiber at 3 W (tip power) for 1 second at 12 spots. A nontreated segment of the LCx served as a control. Two 3-mm long segments were obtained from the treated segment: one to measure the results of potassium (K) induced contraction, and another 3, 4 diaminopyridine (DAP; K channel inhibitor) induced contraction. In 11 instances, coronary angiography of the perfused artery showed less than 50% stenosis after laser treatment. The segments were then mounted isometrically with 1 g tension in Krebs-bicarbonate buffer. Contraction was induced either with 30 mM KCI or 10(-2) M DAP and expressed as developed tension (gram; g). KCI induced vasocontraction of 4.15 +/- 0.93 g in the control, 0.33 +/- 0.71 g in laser irradiated segments (P < 0.0001 vs control), and 0.02 +/- 0.06 g in thermally-treated segments (P < 0.0001 vs control). DAP induced vasocontraction of 5.21 +/- 1.32 g in the control, 0.39 +/- 0.83 g in laser irradiated segments (P < 0.0001 vs control), and 0.07 +/- 0.13 g in thermally treated segments (P < 0.001 vs control). In 4 instances, more than 50% stenosis remained and additional balloon dilatation reduced the stenosis to less than 50%. The lesions also showed reduced vasoreactivity. In vivo thermal angioplasty resulted in reduced vasoreactivity compared to control in 4 anesthetized dogs. Thus, laser and thermal angioplasty reduced vasoreactivity induced by either KCI or 3, 4 DAP. Neither acetylcholine at 10(-6) M nor papaverine at 10(-4) M was able to induce relaxation of treated segments. In conclusion, 1) the lased coronary artery loses its vasoreactivity to either a constrictive or relaxing agent, 2) although stenosis may be produced by laser energy, additional balloon dilatation can reduce residual stenosis, and 3) laser thermal or argon laser angioplasty may prevent severe coronary spasm.