Cardiac histologic findings in patients with life-threatening ventricular arrhythmias of unknown origin

Electrocardiographic features of the presence of occult myocardial disease in patients with VPD-induced cardiomyopathy

Background

Frequent ventricular premature depolarizations (VPDs) can cause reversible cardiomyopathy (CMP). However, many patients maintain a normal left ventricular (LV) function with a high VPD burden. The electrocardiographic characteristics of VPD‐induced CMP have not been elucidated.

Methods

One hundred and eighty (91 men, age; 51 ± 15 years) patients with frequent idiopathic VPDs (>10% VPDs/day or >10 000 VPDs/day) were studied. All patients underwent successful ablation and were then divided into two groups according to the echocardiographic findings before and after the ablation procedure.

Results

Group A (n = 139) had a normal LV function with VPD frequencies, and Group B (n = 41) had reversible LV dysfunction after ablation. The VPD QRS duration (QRSd) was wider in patients with CMP (Group A vs Group B; 137.2 ± 12.0 milliseconds vs 159.7 ± 5.3 milliseconds, P < .001). VPDs with a terminal QRS delay marked by a notch followed by a discrete lower amplitude signal after the peak R wave in any precordial lead were identified. The incidence of terminal signals was higher in the CMP group (Group A vs Group B; 2.1% vs 53.6%, P < .001).

Conclusions

The wider VPD QRSd and terminal QRS delay in patients with VPD‐induced CMP suggest subclinical cell‐to‐cell conduction abnormalities as a potential factor predisposing VPD‐induced CMP.

Right ventricle apex pacing identifies the presence of ventricular premature depolarizations-induced cardiomyopathy

BACKGROUND

A high burden of ventricular premature depolarizations (VPDs) has been associated with potentially reversible left ventricular (LV) dysfunction, termed as VPD-induced cardiomyopathy (CMP). However, many patients maintain normal LV function despite a high VPD burden. The purpose of this study was to identify CMP by right ventricle apex (RVa) pacing method in patients with high VPD burden.

METHODS

A total of 62 patients (28 male; mean age = 50 ± 15 years) with idiopathic VPDs undergoing ablation were enrolled. RVa pacing was recorded in all patients during the procedure. The paced QRS duration (QRSd) during RV pacing was measured from the pacing spike to the latest QRS deflection on any surface electrocardiogram lead. Patients were divided into two groups: reversible VPD-induced CMP (Group R; n  = 15, 14 males, mean age = 54 ± 14 years) and normal LV function (Group N; n = 47, 23 males, mean age = 54 ± 15 years).

RESULTS

The LV ejection fraction (%) was significantly lower in Group R as compared with Group N (Group R, Group N = 36 ± 6, 58 ± 4; P < 0.001); however, LV end-diastolic dimension mm was not significantly different between the two study groups (Group R, Group N = 54 ± 5, 50 ± 6; P = 0.06). Similarly, sinus QRS width (P = 0.10), VPD-burden (P = 0.36), and body surface area (P = 0.75) were not significantly different between Group R and Group N. The QRSd was significantly longer in Group R compared with Group N (177 ± 8 vs 150 ± 14; P < 0.001). Using a QRSd cut-off value of 170.1 ms, VPD-induced CMP was identified with a sensitivity of 73% and a specificity of 97%.

CONCLUSION

RVa pacing with transmyocardial conduction time assessment was a useful method for identifying idiopathic VPD-induced CMP. Using a QRSd cut-off value of 170.1 ms, VPD-induced CMP was identified with a sensitivity of 73% and a specificity of 97%.

Comprehensive Histological and Immunochemical Forensic Studies in Deaths Occurring in Custody

In-custody deaths have several causes, and these include homicide, suicide, natural death from chronic diseases, and unexplained death possibly related to acute stress, asphyxia, excited delirium, and drug intoxication. In some instances, these deaths are attributed to undefined accidents and natural causes even though there is no obvious natural cause apparent after investigation. Understanding these deaths requires a comprehensive investigation, including documentation of circumstances surrounding the death, review of past medical history, drug and toxicology screens, and a forensic autopsy. These autopsies may not always clearly explain the death and reveal only nonspecific terminal events, such as pulmonary edema or cerebral edema. There are useful histologic and biochemical signatures which identify asphyxia, stress cardiomyopathy, and excited delirium. Identifying these causes of death requires semiquantitative morphologic and biochemical studies. We have reviewed recent Bureau of Justice Statistics on in-custody death, case series, and morphological and biochemical studies relevant to asphyxia, stress cardiomyopathy, and excited delirium and have summarized this information. We suggest that regional centers should manage the investigation of these deaths to provide more comprehensive studies and to enhance the expertise of forensic pathologists who would routinely manage potentially complex and difficult cases.

Endomyocardial biopsy findings in patients with ventricular arrhythmias of unknown origin

To evaluate possible occult myocardial disease in patients with ventricular arrhythmias of unknown origin, over 11 years right ventricular endomyocardial biopsies (EMB) were performed on 80 consecutive such patients (29 Females, 51 Males; median age 42 years). Seventy-one (89%) had ventricular tachycardia or fibrillation, 7 (9%) had complex ventricular arrhythmias, and 2 (3%) had premature ventricular beats. None showed clinical evidence of congestive heart failure or significant coronary artery or valvular disease. Endomyocardial biopsies revealed pathologic changes in 70 out of 80 patients (88%). Of the 70 affected, 39 (56%) had nonspecific changes consistent with cardiomyopathy (e.g., myofiber hypertrophy, interstitial and perivascular fibrosis, and vascular sclerosis); 6 (9%) had active myocarditis (Myo); 7 (10%) had borderline Myo; 7 (10%) had small vessel disease; 6 (9%) had changes consistent with arrhythmogenic cardiomyopathy; 2 (3%) had amyloidosis; 2 (3%) had microfibrillar cardiomyopathy, and one (1.0%) showed intravascular organizing thrombus. Thus, EMB reveals a variety of abnormalities in the majority of patients presenting with ventricular arrhythmias without clinical evidence of structural heart disease.

Myocardial tissue characterization by cardiac magnetic resonance imaging using T1 mapping predicts ventricular arrhythmia in ischemic and non-ischemic cardiomyopathy patients with implantable cardioverter-defibrillators

BACKGROUND

Diffuse myocardial fibrosis may provide a substrate for the initiation and maintenance of ventricular arrhythmia. T1 mapping overcomes the limitations of the conventional delayed contrast-enhanced cardiac magnetic resonance (CE-CMR) imaging technique by allowing quantification of diffuse fibrosis.

OBJECTIVE

The purpose of this study was to assess whether myocardial tissue characterization using T1 mapping would predict ventricular arrhythmia in ischemic and non-ischemic cardiomyopathies.

METHODS

This was a prospective longitudinal study of consecutive patients receiving implantable cardioverter-defibrillators in a tertiary cardiac center. Participants underwent CMR myocardial tissue characterization using T1 mapping and conventional CE-CMR scar assessment before device implantation. The primary end point was an appropriate implantable cardioverter-defibrillator therapy or documented sustained ventricular arrhythmia.

RESULTS

One hundred thirty patients (71 ischemic and 59 non-ischemic) were included with a mean follow-up period of 430 ± 185 days (median 425 days; interquartile range 293 days). At follow-up, 23 patients (18%) experienced the primary end point. In multivariable-adjusted analyses, the following factors showed a significant association with the primary end point: secondary prevention (hazard ratio [HR] 1.70; 95% confidence interval [95% CI] 1.01-1.91), noncontrast T1(_native) for every 10-ms increment in value (HR 1.10; CI 1.04-1.16; 90-ms difference between the end point-positive and end point-negative groups), and Grayzone(_2sd-3sd) for every 1% left ventricular increment in value (HR 1.36; CI 1.15-1.61; 4% difference between the end point-positive and end point-negative groups). Other CE-CMR indices including Scar(_2sd), Scar(_FWHM), and Grayzone(_2sd-FWHM) were also significantly, even though less strongly, associated with the primary end point as compared with Grayzone(_2sd-3sd).

CONCLUSION

Quantitative myocardial tissue assessment using T1 mapping is an independent predictor of ventricular arrhythmia in both ischemic and non-ischemic cardiomyopathies.

The proarrhythmic effect of cardiac resynchronization therapy: an issue that should be borne in mind

The demonstrated benefits of cardiac resynchronization therapy (CRT) in reducing mortality and hospitalizations for heart failure, improving NYHA functional class and inducing reverse remodeling have led to its increasing use in clinical practice. However, its potential contribution to complex ventricular arrhythmias is controversial.We present the case of a female patient with valvular heart failure and severe systolic dysfunction, in NYHA class III and under optimal medical therapy, without previous documented ventricular arrhythmias. After implantation of a CRT defibrillator, she suffered an arrhythmic storm with multiple episodes of monomorphic ventricular tachycardia (VT), requiring 12 shocks. Subsequently, a pattern of ventricular bigeminy was observed, as well as reproducible VT runs induced by biventricular pacing. Since no other vein of the coronary sinus system was accessible, it was decided to implant an epicardial lead to stimulate the left ventricle, positioned in the left ventricular mid-lateral wall. No arrhythmias were detected in the following six months. This case highlights the possible proarrhythmic effect of biventricular pacing with a left ventricular lead positioned in the coronary sinus venous system.

Prevalence and clinical relevance of the morphological substrate of ventricular arrhythmias in patients without known cardiac conditions detected by cardiovascular MR

OBJECTIVE

Cardiac MR (CMR) identifies the substrate of ventricular arrhythmia (VA) in cardiomyopathies and coronary heart disease. However, little is known about the value of CMR in patients with VA without previously known cardiac disorders.

METHODS

76 patients with VA (Lown ≥2) without known cardiac disease after regular diagnostic work-up were studied with CMR, and findings were correlated with electrocardiogram (ECG) and electrophysiological stimulation (EPS). Structural abnormalities matching the VA origin as defined by ECG and/or EPS, or a CMR-detected cardiac condition known to cause arrhythmia were defined as VA substrate. CMR findings were defined as clinically relevant, if resulting in a new diagnosis, change of treatment or additional diagnostic procedure.

RESULTS

44/76 patients demonstrated pathological CMR findings. In 24/76 patients, the pathology was detected by CMR and not by echocardiography. CMR-based diagnoses of cardiac disease were established in 20/76 patients, and all were morphological substrates for VA. In seven patients, the location of the CMR finding (scar) directly matched the VA origin. CMR findings resulted in a change of treatment in 21 patients and/or additional diagnostics in 8 patients.

CONCLUSION

Undetected cardiac conditions are frequent causes of VA. This is the first study demonstrating the value of CMR for detection of morphological substrate and/or underlying cardiac disorders in VA patients without known cardiac disease.

ADVANCES IN KNOWLEDGE

The high incidence of clinically relevant CMR findings which were not detected during initial diagnostic work-up strongly supports the use of CMR to screen VA patients for underlying heart disease.

Advances in ablation of ventricular tachycardia in nonischemic cardiomyopathy

Management of patients with nonischemic cardiomyopathy (NICM) and ventricular tachycardia (VT) remains challenging. The role of catheter ablation for VT continues to evolve for these patients. Prior reports have described the location of the arrhythmogenic substrate for patients with NICM to be frequently located along the basal left ventricle, with an epicardial predilection. Furthermore, predictors for identifying whether mapping the endocardium or epicardial surface of the heart have been identified for improved success of VT ablation in this patient population. This chapter will review the latest advances in catheter ablation of ventricular tachycardia in patients with NICM.

Endomyocardial biopsy--when and how?

Endomyocardial biopsy is a commonly performed useful procedure utilized for the evaluation of cardiac tissue. Biopsy may be used to monitor transplant rejection, but it has many other applications including the evaluation of myocarditis, cardiomyopathy, chest pain, arrhythmia, and secondary involvement by systemic diseases. Drug toxicity may be evaluated and neoplasms may be biopsied. Recent developments include advances in myocardial and viral molecular biology and advances in image or electrophysiology guided biopsy. The utility of endomyocardial biopsy is reviewed with consideration of these advances.

Characterization of the arrhythmogenic substrate in ischemic and nonischemic cardiomyopathy implications for catheter ablation of hemodynamically unstable ventricular tachycardia

OBJECTIVES

The purpose of this study was to compare the characteristics and prevalence of late potentials (LP) in patients with nonischemic cardiomyopathy (NICM) and ischemic cardiomyopathy (ICM) etiologies and evaluate their value as targets for catheter ablation.

BACKGROUND

LP are frequently found in post-myocardial infarction scars and are useful ablation targets. The relative prevalence and characteristics of LP in patients with NICM is not well understood.

METHODS

Thirty-three patients with structural heart disease (NICM, n = 16; ICM, n = 17) referred for catheter ablation of ventricular tachycardia were studied. Electroanatomic mapping was performed endocardially (n = 33) and epicardially (n = 19). The LP were defined as low voltage electrograms (<1.5 mV) with onset after the QRS interval. Very late potentials (vLP) were defined as electrograms with onset >100 ms after the QRS.

RESULTS

We sampled an average of 564 +/- 449 points and 726 +/- 483 points in the left ventricle endocardium and epicardium, respectively. Mean total low voltage area in patients with ICM was 101 +/- 55 cm(2) and 56 +/- 33 cm(2), endocardial and epicardial, respectively, compared with NICM of 55 +/- 41 cm(2) and 53 +/- 28 cm(2), respectively. Within the total low voltage area, vLP were observed more frequently in ICM than in NICM in endocardium (4.1% vs. 1.3%; p = 0.0003) and epicardium (4.3% vs. 2.1%, p = 0.035). An LP-targeted ablation strategy was effective in ICM patients (82% nonrecurrence at 12 +/- 10 months of follow-up), whereas NICM patients had less favorable outcomes (50% at 15 +/- 13 months of follow-up).

CONCLUSIONS

The contribution of scar to the electrophysiological abnormalities targeted for ablation of unstable ventricular tachycardia differs between ICM and NICM. An approach incorporating LP ablation and pace-mapping had limited success in patients with NICM compared with ICM, and alternative ablation strategies should be considered.

Myocarditis

Viruses are the most common cause of myocarditis in economically advanced countries.

Enteroviruses and adenoviruses are the most common etiologic agents.

Viral myocarditis is a triphasic process. Phase 1 is the period of active viral replication in the myocardium during which the symptoms of myocardial damage range from none to cardiogenic shock. If the disease process continues, it enters phase 2, which is characterized by autoimmunity triggered by viral and myocardial proteins. Heart failure often appears for the first time in phase 2. Phase 3, dilated cardiomyopathy, is the end result in some patients. Diagnostic procedures and treatment should be tailored to the phase of disease.

Viral myocarditis is a significant cause of dilated cardiomyopathy, as proved by the frequent presence of viral genomic material in the myocardium, and by improvement in ventricular function by immunomodulatory therapy.

Myocarditis of any etiology usually presents with heart failure, but the second most common presentation is ventricular arrhythmia. As a result, myocarditis is one of the most common causes of sudden death in young people and others without preexisting structural heart disease.

Myocarditis can be definitively diagnosed by endomyocardial biopsy. However, it is clear that existing criteria for the histologic diagnosis need to be refined, and that a variety of molecular markers in the myocardium and the circulation can be used to establish the diagnosis.

Treatment of myocarditis has been generally disappointing. Accurate staging of the disease will undoubtedly improve treatment in the future. It is clear that immunosuppression and immunomodulation are effective in some patients, especially during phase 2, but may not be as useful in phases 1 and 3. Since myocarditis is often selflimited, bridging and recovery therapy with circulatory assistance may be effective. Prevention by immunization or receptor blocking strategies is under development.

Giant cell myocarditis is an unusually fulminant form of the disease that progresses rapidly to heart failure or sudden death. Rapid onset of disease in young people, especially those with other autoimmune manifestations, accompanied by heart failure or ventricular arrhythmias, suggests giant cell myocarditis.

Peripartum cardiomyopathy in economically developed countries is usually the result of myocarditis.

Chronic kidney disease in patients with chronic heart failure--impact on intracardiac conduction, diastolic function and prognosis

BACKGROUND

In patients with chronic heart failure (CHF), chronic kidney disease (CKD) is associated with increased morbidity and mortality, but contributing mechanisms are not well defined. This study tested the impact of CKD on intracardiac conduction, diastolic function and prognosis in patients with underlying CHF.

METHODS

We prospectively enrolled 269 patients with stable CHF, of whom 135 had CKD (estimated glomerular filtration rate (eGFR)<60 ml/min/1.73 m(2)). Echo measurements comprised left ventricular dimensions/volumes, ejection fraction, mitral E/A-ratio, deceleration time and tissue Doppler mitral annular velocities (S', E', A'). PQ and QRS intervals were derived from the 12-lead ECG. A cardiac event (cardiac death or urgent cardiac transplantation) was defined as combined study end point.

RESULTS

Patients with CKD had longer PQ and QRS intervals, and were in a poorer NYHA functional class as compared to patients without CKD. In patients with CKD, the mitral annular E' velocity was lower, the mitral E/E'-ratio was higher and a restrictive mitral filling pattern was more frequent. By linear regression analysis, PQ and QRS intervals and the mitral E/E'-ratio were inversely related to the eGFR. During a follow-up of 507+/-375 days, 39 patients suffered a cardiac event. In CKD patients, outcome was markedly poorer as compared to those without CKD (event-free survival rate 51% vs. 87% in those without KD, p=0.001)

CONCLUSIONS

In patients with CHF, CKD is associated with impaired intracardiac conduction and progressive diastolic dysfunction. Both mechanisms may contribute to increased morbidity and mortality of such patients.

Clinical and epidemiological aspects of cardiomyopathies: a critical review of current knowledge

Five years after the second report of the WHO/ISFC Task Force on the definition and classification of cardiomyopathies (CM), a critical review of the matter appears well-timed. The need for a correct definition of myocardial diseases is emphasized by considering them the result of a 'direct' injury due to different known and unknown causes and not a consequence of ischemic disease or of pressure and/or volume overload. This is in order to eliminate terms like ischemic CM, valvular CM, and hypertensive CM, which are a source of confusion. The concept of myocardial injury is also reviewed. This should not only include the structural/organic macroscopic injury, but also the subcellular, ultrastructural, and molecular damage (mostly of genetic origin) of the contracting element proteins, of citosol, sarcolemma and cell membrane ion channels. As the myocardium is a complex structure, made of common fibers and of specific conduction tissue, injury may be clinically identified either by ventricular function impairment or by bioelectric function defects, i.e. tachyarrhythmias and/or bradyarrhythmias, which sometimes are the unique manifestation of the disease (arrhythmogenic CM, in the strict sense). On the basis of the morpho-functional alterations, CMs may be classified as dilated CM (which could be better identified as hypokinetic CM, referring to the functional aspect, because the morphologic aspect is not always present), hypertrophic CM, restrictive CM, and arrhythmogenic CM (including not only arrhythmogenic right ventricular CM, but also other forms, like the so-called arrhythmias of the 'apparently' healthy heart, due to 'occult' myocardial injury). Moreover, these forms may present in association, like mixed CM (dilated-arrhythmogenic, dilated-hypertrophic, etc.). From an etiologic point of view, it is advisable to maintain the distinction between specific CM, due to a known cause, and primary or idiopathic CM, including, together with sporadic forms of an unknown origin, familial forms of a genetic origin, depending on alterations of contractile or regulating functional proteins, when myocardial injury is the sole manifestation (idiopathic) of clinical picture. The most modern etiopathogenetic, pathophysiological, and clinical features of each form of CM are briefly described in order to suggest a complete definition of the disease and to state a clinical-epidemiological setting that encompasses the current knowledge.

The combination ace-inhibitors plus canreonate in patients with anterior myocardial infarction: safety and tolerability study

BACKGROUND

There is recent evidence that aldosterone (ALDO) exerts pro-fibrotic effects, acting via the mineral-corticoid receptors in cardiovascular tissues and partial aldosterone escape during ACE-inhibition treatment occurs.

METHODS

A double blind randomised study was performed to evaluate the feasibility, and tolerability of the administration of the 25 mg/day of canreonate plus captopril versus captopril alone in patients with anterior AMI unsuitable for thrombolysis and/or not receiving thrombolytic treatment, and unreperfused after thrombolysis. Fifty five patients hospitalised for anterior AMI,with a serum creatinine concentration <2.0 mg/dl and a serum K concentration <5.0 mmol per liter were randomised in 2 groups: Group A included 27 patients who received captopril and 25 mg i.v. of canreonate (1 mg/h for the 1st 72 h and then orally 25 mg/day. Group B (28 patients) received captopril and placebo. Ten days after admission they underwent echocardiography to determine end systolic volume (ESV), ejection fraction (EF), End diastolic diameter EDD, E/A ratio, E deceleration time (dec. time) and isovolumetric relaxation time (IVRT), E and A peak velocities.

RESULTS

All patients did not show patency of the infarct related artery (7-10 days after AMI) and the 2 groups were similar in regard to age, sex, diabetes, smoking habits, hypertension, CK enzymatic peak, adjuvant therapy, EF, ESV, and incidence of CABG/PTCA. One patient only showed increase of serum K>5.5 mmol/dl and creatinine >2.0 mg per liter after 10 days of treatment (group A). The mitral E/A ratio was higher in group A than group B (0.85+/-0.18 and 0.75+/-0.14) respectively, P=0.024. Creatinine, blood urea and serum K did not show significant differences between groups. No side effects were observed during the study period. The incidence of vessel diseases was similar in both groups.

CONCLUSIONS

Our data suggest that the combination of captopril plus canreonate in feasible in early treatment of AMI patients.

Spironolactone in the treatment of congestive heart failure

OBJECTIVE

To evaluate evidence supporting the use of spironolactone in managing congestive heart failure.

DATA SOURCES

Literature accessed through MEDLINE (January 1966-December 1999) and cross-referencing of selected articles. Search terms included spironolactone and heart failure.

DATA SYNTHESIS

Heart failure is a leading cause of morbidity and mortality. Through aldosterone antagonism, spironolactone may be an effective pharmacotherapeutic addition to patients not responding to standard drug therapy for heart failure.

RESULTS

Clinical trials have demonstrated that, in patients with heart failure, spironolactone improves laboratory indices, quality of life, and morbidity. Recently, spironolactone has been demonstrated to improve the survival of patients with New York Heart Association (NYHA) III or IV heart failure.

CONCLUSIONS

Spironolactone use should be considered in patients with NYHA Class III or IV heart failure.

Sudden cardiac death with apparently normal heart

BACKGROUND

Mechanisms of sudden cardiac death (SCD) in subjects with apparently normal hearts are poorly understood. In survivors, clinical investigations may not establish normal cardiac structure with certainty. Large autopsy series may provide a unique opportunity to confirm structural normalcy of the heart before reviewing a patient's clinical history.

METHODS AND RESULTS

We identified and reexamined structurally normal hearts from a 13-year series of archived hearts of patients who had sudden cardiac death. Subsequently, for each patient with a structurally normal heart, a detailed review of the circumstances of death as well as clinical history was performed. Of 270 archived SCD hearts identified, 190 were male and 80 female (mean age 42 years); 256 (95%) had evidence of structural abnormalities and 14 (5%) were structurally normal. In the group with structurally normal hearts (mean age 35 years), SCD was the first manifestation of disease in 7 (50%) of the 14 cases. In 6 cases, substances were identified in serum at postmortem examination without evidence of drug overdose; 2 of these chemicals have known associations with SCD. On analysis of ECGs, preexcitation was found in 2 cases. Comorbid conditions identified were seizure disorder and obesity (2 cases each). In 6 cases, there were no identifiable conditions associated with SCD.

CONCLUSIONS

In 50% of cases of SCD with structurally normal hearts, sudden death was the first manifestation of disease. An approach combining archived heart examinations with detailed review of the clinical history was effective in elucidating potential SCD mechanisms in 57% of cases.

Ventricular arrhythmias in normal hearts

Idiopathic ventricular tachycardia (VT) is characterized by two predominant forms. The most common form originates from the right ventricular outflow tract and presents as repetitive monomorphic VT or exercise-induced VT. The tachycardia is adenosine sensitive and is thought to be because of cAMP-mediated triggered activity. The other major form of idiopathic VT is owing to verapamil-sensitive intrafascicular re-entrant tachycardia, which most often originates in the region of the left posterior fascicle. Both forms of idiopathic VT can be readily treated with radiofrequency catheter ablation.

Endomyocardial biopsy findings in patients with atrioventricular block in the absence of apparent heart disease

The purpose of this study was to examine the histopathological findings of right ventricular endomyocardial biopsies from ten patients less than 60 years of age (47 +/- 9.8 (mean +/- SD) years) with documented atrioventricular block but without apparent heart disease. They underwent electrophysiological testing, echocardiography, coronary angiography, and right ventricular endomyocardial biopsy. Biopsy specimens were assessed for morphologic changes in myocyte diameter, fibrosis, disarray, and degeneration. Electrophysiological testing demonstrated atrioventricular nodal block in 2, intra-His bundle block in 2, and infra-His bundle block in 6 patients. Histology revealed evidence of myocardial fibrosis with either myocyte hypertrophy or disarray in 7 of the 10 patients. The results of electrophysiological testing did not correlate with the histopathological findings or severity. In one patient, heart failure appeared during the follow-up period. We conclude that patients with atrioventricular block of unknown etiology have histological abnormalities of the ventricular endomyocardium in addition to the conduction system disturbances. We consider such cases as constituting one of the disease groups of cardiomyopathy, and suggest that it is necessary to follow up the clinical course in these patients.

Histopathologic aspects of endomyocardial biopsy in pediatric patients with idiopathic ventricular tachycardia

PURPOSE

The present study aimed to investigate the clinicopathologic findings and histopathologic characteristics of endomyocardial biopsy in pediatric patients with idiopathic ventricular tachycardia.

METHODS

Histopathological findings of endomyocardial biopsy from 17 patients aged 7-15 years with idiopathic ventricular tachycardia (VT) but no organic heart disease were examined. Patients considered to have cardiomyopathy of the dilated, hypertrophic or specific form or arrhythmogenic right ventricular cardiomyopathy were excluded from this study.

RESULTS

Advanced histopathologic findings, including myocyte hypertrophy, degeneration, interstitial fibrosis and disarrangement of muscle bundles, were disclosed in three cases (17.6%). One of these cases exhibited sustained VT with left bundle branch block configuration and showed increased frequency of VT during exercise testing. The remaining two cases had non-sustained VT with multifocal origin and had syncope episodes. Another 14 cases showed mild or no significant findings in the biopsy.

CONCLUSIONS

These results indicate that advanced histopathology in endomyocardial biopsy is occasionally disclosed in cases of idiopathic VT, especially those of exercise-related VT or multifocal VT, and that these patients may be considered as having heart muscle disease.

Tachycardias in children originating in the right ventricular outflow tract: lack of clinical features predicting the presence and severity of the histopathological substrate

The aim was to determine whether the clinical features of tachycardias originating from the right ventricular outflow tract in children with an apparently normal heart could predict the presence and the severity of the histopathological substrate. Thirteen children (median age 6 years; range 6 months-12 years) with tachycardia originating from the right ventricular outflow tract of apparently normal hearts, were assessed by echocardiography, heart catheterization with angiography, endomyocardial biopsy (13 patients) and magnetic resonance imaging (MRI) (nine patients). Tachycardia was symptomatic in six and sustained in nine. Endomyocardial biopsy and MRI revealed acute myocarditis in five patients (38%), fatty infiltration of the right ventricle in two (15%), and minor histologic abnormalities in three (23%). Myocarditis was diagnosed in three of nine patients with sustained ventricular tachycardia, as opposed to two of four with non-sustained tachycardia (p = NS); in three of six symptomatic versus two of seven asymptomatic patients (p = NS); and in two of eight patients in whom ventricular tachycardia was induced during exercise testing as opposed to one of three in which it was not inducible (p = NS). A histopathological substrate was found in six of nine patients with sustained ventricular tachycardia, and in all four with non-sustained tachycardia (p = NS); in five of six patients with symptoms versus five of seven asymptomatic patients (p = NS); and in five of eight with inducible ventricular tachycardia during exercise testing versus all three in whom it was not inducible (p = NS). The mean rate of tachycardia was 184+/-39 beats min(-1) in patients with myocarditis, as opposed to 171+/-48 in patients without myocarditis (p = NS); and 163+/-33 in patients with a histopathological substrate compared with 210+/-65 in patients without a histopathological substrate (p = NS). It is concluded that a histopathological substrate is present in the greater majority of children affected by the so-called right ventricular outflow tract tachycardia, but that the clinical features of the tachycardia do not predict the presence and the severity of this histopathological substrate.

Hemodynamic monitoring prior to and at the time of death in status epilepticus

Status epilepticus (SE) is a common neurological and medical emergency. Despite the significant mortality associated with SE, no human data have been available regarding cardiovascular changes prior to death in patients with this condition. This study was conducted to measure hemodynamic trends in the 24 h prior to death in a series of 24 prospectively evaluated SE patients. Two distinct cardiovascular patterns of mean arterial pressure (MAP) and heart rate (HR) were observed. Ten patients had a gradual decline in MAP and/or HR, and this group was designated as having gradual cardiac decompensation (GCD). The remaining 14 patients showed no significant changes in either MAP or HR up to the time of death. This group of patients was designated as having acute cardiac decompensation (ACD). The changes in MAP and HR over the last 24 h prior to death between the GCD and ACD groups were statistically significant. Ninety percent of the GCD patients had a history of multiple risk factors for arteriosclerotic cardiovascular disease (ASCVD), while only 30% of the ACD group had a history of multiple risk factors for ASCVD. The results provide the first human data of cardiovascular events immediately preceding death in SE patients. We propose that further investigation of the cardiovascular pathophysiology of SE may provide new therapeutic interventions which could decrease the significant mortality associated with SE.

Diagnosis of cardiac abnormalities in patients with nonischemic tachyarrhythmias: additional value of MR imaging

PURPOSE

To assess the contribution of cardiac magnetic resonance (MR) imaging in the evaluation of patients with nonischemic tachyarrhythmias and equivocal diagnosis following echocardiography and cardiac angiography.

METHODS AND RESULTS

Twenty-five patients with nonischemic tachyarrhythmias and equivocal diagnosis were studied using MR imaging. Before the MR examination all patients underwent two-dimensional echocardiography and cardiac catheterization. The type of additional information, obtained with MR imaging, ranged from confirming a suspected diagnosis in 5 patients (20%) to the identification of new important anatomic or functional information, allowing a correct diagnosis in 18 patients (72%). In two patients (8%) the MR diagnosis was incomplete.

CONCLUSION

MR imaging may be an important additional diagnostic tool in the evaluation of cardiac abnormalities in patients with nonischemic tachyarrhythmias.

Idiopathic ventricular fibrillation: clinical, electrophysiologic characteristics and long-term outcomes

The long-term prognosis, including risks of arrhythmic recurrence of idiopathic ventricular fibrillation (VF), is uncertain; moreover, the role of electrophysiologic study in the diagnosis and guiding of antiarrhythmic drugs therapy for idiopathic VF remains controversial. The purpose of this study was to study the clinical features, electrophysiologic characteristics and long-term clinical outcomes of six consecutive patients (five males) who had at least one episode of aborted cardiac arrest (5 patients) or syncope (1 patients) with documentation of ventricular fibrillation (VF) in the absence of apparent heart disease. Idiopathic VF was diagnosed by exclusion. All patients underwent the electrophysiologic study including intravenous antiarrhythmic drug testing. Recurrences of VF after therapy and the long-term outcomes were assessed. The mean age at the first episode was 43+/-19 years (range from 16 to 63 years). All patients had sustained VF induced by double (3 patients) or triple (3 patients) ventricular extrastimuli at a paced cycle length of 400 or 500 ms from the right ventricular apex. Intravenous procainamide and/or mexiletine could suppress the reinduction of sustained VF in 4 (67%) of 6 patients. Recurrence of VF (documented VF attack, sudden cardiac arrest or syncope) was observed in 3 (100%) of 3 patients who received procainamide or mexiletine alone. Four patients (including 3 patients who experienced recurrence) received amiodarone alone or in combination with mexiletine, and these drugs could effectively prevent recurrence of VF. One patient with exercise-induced VF remained asymptomatic without any treatment during a follow-up period of 95 months. Another patient received an implantable cardioverter-defibrillator without concomitant antiarrhythmic drug therapy and had no discharge of electrical shock during 28 months of follow-up. During a mean follow-up period of 64+/-40 months (range from 28 to 128 months), all the patients were alive except patient No. 2 who died of acute hepatic failure. In conclusion, electrophysiologic study is a reliable diagnostic method, but it was of limited value in guiding antiarrhythmic drug therapy for preventing recurrence of idiopathic VF. Class I drug alone was associated with a high recurrence rate (100%) despite predictions that it would be effective by the electrophysiologic study. Amiodarone alone or in combination with mexiletine effectively prevented the recurrence of VF during the long-term follow-up along with a favourable outcome.

Significance of morphological abnormalities detected by MRI in patients undergoing successful ablation of right ventricular outflow tract tachycardia

BACKGROUND

MRI can demonstrate subtle morphological changes of the right ventricle in patients with idiopathic right ventricular outflow tract tachycardia (RVOT). The present study examines the incidence and significance of right ventricular (RV) abnormalities detected by MRI with respect to the site of successful radiofrequency catheter ablation of the clinical tachycardia.

METHODS AND RESULTS

The study population comprised 20 patients (mean age, 40+/-12 years) undergoing elimination of recurrent RVOT by radiofrequency catheter ablation. MRI studies were performed before ablation to assess RV volumes and function, as well as structural abnormalities of the RV myocardium. Ten healthy age- and sex-matched subjects served as control subjects. The successful ablation sites, as documented by radiographs of the catheter position, were compared with MRI findings. Patients with RVOT showed no difference in respect to RV volumes and ejection fractions compared with control subjects. Whereas RV abnormalities were limited to prominent fatty deposits of the right atrioventricular groove extending into the inlet portion of the RV wall in 2 of 10 control subjects, MRI studies demonstrated morphological changes of the RV free wall in 13 (65%) of 20 patients with RVOT, including presence of fatty tissue (n=5), wall thinning (n=9), and dyskinetic wall segments (n=4). Eight of these patients had additional fat deposits, thinning, or a saccular aneurysm in the RV outflow tract, corresponding with the ablation site in 6 patients.

CONCLUSIONS

In RVOT, structural abnormalities of the right ventricle can be detected in a substantial number of patients despite normal RV volumes and global function. MRI abnormalities within the RV outflow tract are significantly associated with the origin of tachycardia.

Idiopathic ventricular fibrillation

Idiopathic ventricular fibrillation is defined as cardiac arrest in the absence of structural heart disease and other identifiable causes of ventricular fibrillation. It occurs in 1% to 9% of survivors of out-of-hospital cardiac arrest. The mean age of these patients is 35 to 40 years, and 70% to 75% are male. The pathogenesis is unknown; psychosocial factors may play a role. Baseline clinical characteristics have not been found to identify the 20% to 30% of patients who will have recurrent cardiac arrest. At present, implantation of an automatic defibrillator is the treatment of choice. Two registries have been established to enhance our knowledge of this unusual catastrophic entity.

Adenosine-sensitive ventricular tachycardia: right ventricular abnormalities delineated by magnetic resonance imaging

BACKGROUND

Adenosine-sensitive ventricular tachycardia (VT) is thought to be due to cAMP-mediated triggered activity. It typically originates from the RVOT and occurs in patients with apparently normal hearts. Using magnetic resonance imaging (MRI), we tested the hypothesis that adenosine-sensitive VT occurs in patients without structural heart disease.

METHODS AND RESULTS

Fourteen patients (9 women; age, 47+/-19 years) presented with sustained VT (n=3), repetitive monomorphic VT (n=7), or both (n=4). VT terminated with adenosine in each patient and was sensitive to vagal maneuvers in 9 of 11 and verapamil in 10 of 12. VT originated from the right ventricular outflow tract in 10 patients, the right ventricular apex in 1, and the left ventricular septum in 3. Conventional studies included normal signal-averaged ECGs in 9 of 9, normal right ventricular echocardiography in 10 of 10, and normal left ventriculography and coronary angiography in 6 of 7. In contrast, MRI scans were abnormal in 10 of 14 patients. These abnormalities included focal thinning (6), fatty infiltration (4), and wall motion abnormalities (4) of the right ventricle. The most common site of MRI abnormalities was the right ventricular free wall, but there was a poor correlation between the site of MRI abnormalities and the origin of VT. Among 18 control patients without clinical heart disease, thinning of the right ventricular wall was noted in only 1 patient (patients versus control subjects, P=.0001).

CONCLUSIONS

Patients with idiopathic adenosine-sensitive VT comprise a heterogeneous group as assessed by MRI, with 70% demonstrating mild structural abnormalities. However, it is unlikely that these findings are causally related to tachycardia, and the functional significance of these anatomic abnormalities is uncertain.

Idiopathic dilated cardiomyopathy: familial prevalence and HLA distribution

OBJECTIVES

To compare HLA distribution in familial and non-familial dilated cardiomyopathy, because a serum marker that could identify families at risk of developing dilated cardiomyopathy should be of use in screening for the disease.

PATIENTS

100 patients with dilated cardiomyopathy.

METHODS

200 first degree relatives from 56 of the proband families were screened for dilated cardiomyopathy by echocardiography. The HLA profile of the patients with dilated cardiomyopathy, as well as of the familial and non-familial subgroups, was compared with that of 9000 normal controls.

RESULTS

The familial prevalence of dilated cardiomyopathy in this patient group was "definite" in 14 of 56 (25%) and "possible" in 25 of 56 (45%). The HLA-DR4 frequency in the 100 patients with dilated cardiomyopathy was similar to that in the 9000 controls (39% v 32%). However, the DR4 subtype was significantly more common in the 25 probands with a familial tendency to dilated cardiomyopathy than in the 31 probands with non-familial dilated cardiomyopathy (68% v 32%; P < 0.05).

CONCLUSIONS

The present finding supports an HLA linked predisposition to familial dilated cardiomyopathy. The HLA type DR4 was significantly more common in familial than in non-familial cases. The DR4 halotype was associated with two thirds of the families at risk for dilated cardiomyopathy.

Survivors of out-of-hospital cardiac arrest with apparently normal heart. Need for definition and standardized clinical evaluation. Consensus Statement of the Joint Steering Committees of the Unexplained Cardiac Arrest Registry of Europe and of the Idiopathic Ventricular Fibrillation Registry of the United States

BACKGROUND

A wide variety of structural abnormalities are associated with the vast majority of cardiac arrests. However, there is no evidence of structural heart disease in approximately 5% of victims of sudden death, indicating that cardiac arrest in the absence of organic heart disease is more common than previously recognized. The risk of recurrence and the acute and long-term response to therapy are important but unanswered questions. Data from the small series reported so far are of limited value because of the lack of uniform criteria to define and diagnose idiopathic ventricular fibrillation (IVF).

METHODS AND RESULTS

This report originates from a Consensus Conference convened by the Steering Committees of the European (UCARE) and North American (IVF-US) Registries on IVF under the auspices of the Working Group on Arrhythmias of the European Society of Cardiology. Its objective is to provide a unified definition of IVF and to outline the investigations necessary to make this diagnosis. Minimal diagnostic tests for the exclusion of an underlying structural heart disease include non-invasive (blood biochemistry, physical examination and clinical history, ECG, exercise stress test, 24-hour Holter recording, and echocardiogram) and invasive (coronary angiography, right and left ventricular cineangiography, and electrophysiological study) examinations. Programmed electrical stimulation, ventricular biopsy, and ergonovine test during coronary angiography are recommended but not mandatory.

CONCLUSIONS

It is recognized that despite careful evaluation, conditions such as focal cardiomyopathy, myocarditis, or fibrosis and transient electrolyte abnormalities may remain silent. Therefore, patients should undergo careful follow-up, with noninvasive tests repeated every year. The existence of a unified terminology will allow meaningful comparison of data collected by different investigators and will thus contribute to a better understanding of IVF.

Idiopathic right ventricular outflow tract tachycardia: a clinical approach

Right ventricular outflow tract (RVOT) tachycardia is the most common form of idiopathic ventricular tachycardia (VT). Phenotypically, RVOT tachycardia segregates into two predominant forms, one characterized by repetitive monomorphic nonsustained VT and the other by paroxysmal exercise induced sustained VT. There is an increasing body of evidence to support the concept that both forms of tachycardia reflect disparate clinical manifestations of an identical cellular mechanism (i.e., cAMP-mediated triggered activity), which is identified clinically by the tachycardia's sensitivity to adenosine. The clinical characteristics, natural history, and approaches to therapy of RVOT tachycardia are delineated herein.

Ventricular tachycardia initiated solely by reduced pacing rate during routine pacemaker follow-up

Ventricular arrhythmias during a pacemaker follow-up have been previously reported, usually in conjunction with temporary asynchronous stimulation of a demand pacemaker through magnet application or by increased myocardial excitability, for example, following a myocardial infarction. The subject of this report, an 82-year-old pacemaker patient, had been VVI-paced without problems for the past 11 years. As an aid in determining the sensing threshold, the pacemaker lower rate was reduced from 70 to 40 beats/min. A ventricular tachycardia of 240 beats/min was induced, most likely following short-long cycles; syncope resulted. To our knowledge, this is the first report of induction of a ventricular tachycardia during pacemaker follow-up solely by reduction of pacing rate and not by asynchronous pacing. This case demonstrates an additional potential risk associated with pacemaker rate manipulation during pacemaker follow-up.

Electrophysiological findings in idiopathic recurrent ventricular fibrillation: special reference to mode of induction, drug testing, and long-term outcomes

Electrophysiological studies can be useful in the presence of idiopathic ventricular fibrillation (VF) and may be used when selecting antiarrhythmic drugs. However, the yield, the mode, and the long-term reproducibility of the induction of VF have not yet been fully elucidated. Eight patients with idiopathic VF underwent electrophysiological study. The mean age (+/- SD) was 45 +/- 17 years. Six were males and two were females. Diagnosis was done by exclusion. VF was induced in 6 (75%) of 8 patients using double extra stimuli at coupling intervals of 233 +/- 39 and 191 +/- 20 ms for the first and second extra stimuli, respectively. Of note, VF was induced by stimulation exclusively at the origin of the premature ventricular beat, which was the first complex of VF in two patients. In another patient, VF was initiated by two premature stimuli and also by a pause produced by rapid pacing. The inducibility of VF was reproduced 9-18 months after the first induction in all of the four patients studied. When the ability of antiarrhythmic drugs to suppress VF inducibility was confirmed, no recurrence was observed during the follow-up period of 40-160 months, but a recurrence of VF was observed in one of two nonresponders. In one patient, amiodarone administration failed in preventing VF induction 9 months after initiation of therapy, and reassessment of long-term drug-efficacy might be indicated in some patients. In conclusion, idiopathic VF was highly inducible (75%) with double extra stimuli. In this study, it was induced from a specific site (2/8) or by a pause (1/8). Induction of VF seemed to be reproduced 9-18 months after the first study. The outcome was considered favorable when the inducibility of VF was suppressed by antiarrhythmic drugs.

Fractionated electrograms in dilated cardiomyopathy: origin and relation to abnormal conduction

OBJECTIVES

We sought to investigate the origin of the fractionated electrogram and its relations to abnormal conduction in cardiomyopathic myocardium.

BACKGROUND

Patients with dilated cardiomyopathy have a high incidence of ventricular tachycardias. Electrograms recorded in these patients are often fractionated.

METHODS

High resolution mapping (200-microM interelectrode distance) of the electrical activity was carried out in 11 superfused papillary muscles and 6 trabeculae from 7 patients who underwent heart transplantation because of dilated cardiomyopathy. Similar measurements were taken in four papillary muscles from dog hearts in which electrical barriers had been artificially made. Ten human preparations were studied histologically.

RESULTS

All preparations revealed sites with fractionated electrograms. In three human preparations, activation patterns showed a discernible line of activation block running parallel to the fiber direction. Fractionated electrograms were recorded at sites contiguous to the line of block. In five preparations, fractionated electrograms were recorded at sites where lines of block were not identified. In these preparations, electrical barriers consisted of short stretches of fibrous tissue. In the remaining nine preparations, fractionated electrograms were recorded, both from sites contiguous to distinct obstacles and sites without evidence of a barrier.

CONCLUSIONS

Our observations showed that fractionated electrograms recorded in myocardium damaged by cardiomyopathy were due to both distinct, long strands and short stretches of fibrous tissue. Delayed conduction was caused by curvation of activation around the distinct lines of block and by the wavy course of activation between the short barriers. The latter reflects extreme nonuniform anisotropy.

Favorable effects of immunosuppressive therapy in children with dilated cardiomyopathy and active myocarditis

Among 68 children with severe dilated cardiomyopathy, 43 (aged 10 months to 15 years) presented with active myocarditis, diagnosed by endomyocardial biopsy. They were divided into four treatment groups: I, controls: 9 patients submitted to conventional treatment (digitalis, diuretics, and vasodilators) for 8.1 +/- 0.7 (SD) months; II, prednisone: 12 patients received conventional therapy plus prednisone; III, azathioprine: 16 patients submitted to conventional therapy plus prednisone and azathioprine; IV, cyclosporine: 13 patients treated with conventional therapy plus prednisone and cyclosporine. Immunosuppressive therapy was maintained for a mean of 8.4 +/- 1.2 months. They were submitted to noninvasive (electrocardiogram, chest radiograph, Doppler echocardiogram, and radioisotopic scintigraphy) and invasive (hemodynamic) studies. In the control group only 2 of 9 patients showed clinical and hemodynamic improvement and 1 of 4, histologic regression of the myocarditis. Among patients submitted to conventional therapy plus prednisone, 3 of 12 presented clinical and hemodynamic improvement; 2 of 5 also showed histologic regression of inflammatory process. By contrast, patients treated with azathioprine or cyclosporine associated with prednisone had significantly better results: 13 of 16 and 10 of 13 patients, respectively, had clinical and hemodynamic improvement; all 6 patients in the azathioprine group and all 4 patients in the cyclosporine group had histologic regression of the myocarditis. Two patients in the prednisone group, one in the azathioprine group, and one in the cyclosporine group died during treatment, in cardiogenic shock. In our experience immunosuppressive therapy with azathioprine or cyclosporine associated with prednisone improves the prognosis of children with active myocarditis and severe ventricular dysfunction.

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.

Results of biventricular endomyocardial biopsy in survivors of cardiac arrest with apparently normal hearts

Seventeen young patients (10 males and 7 females, aged 14 to 38 years, mean 26.4) without overt organic heart disease, who had been resuscitated from sudden cardiac arrest and referred to our institution during the period 1984 to 1993 for diagnostic evaluation and electrophysiologic study-guided antiarrhythmic therapy, were studied. Patients underwent noninvasive (electrocardiography, echocardiography [2-dimensional and Doppler], and magnetic resonance imaging) and invasive (left ventricular [LV], right ventricular [RV], and coronary angiography, ergonovine testing, electrophysiologic study, and biventricular endomyocardial biopsy) cardiac studies. Six to 8 biopsy fragments per patient were processed for histology and electron microscopy and read by a pathologist blinded to clinical data. Antiarrhythmic drug testing included amiodarone, propafenone, and metoprolol. A cardioverter-defibrillator was implanted in patients with persistently inducible sustained ventricular tachycardia or ventricular fibrillation. Sequential cardiac biopsy specimens were obtained in patients with active myocarditis undergoing immunosuppressive treatment. Periodic 3-month follow-ups included echocardiography and Holter monitoring. Two groups of patients were distinguished by invasive and noninvasive examinations: group I consisted of 9 patients with entirely normal parameters; group II consisted of 8 patients with structural, nonspecific cardiac abnormalities. In this latter group, mild to moderate dilatation and hypokinesia of the left ventricle were documented in 4 patients, concentric LV hypertrophy was seen in three patients, and RV dysfunction was noted in 1 patient. Histologic examination was abnormal in in all patients and revealed specific lesions in 65% of them; LV biopsy specimens allowed a diagnosis in 3 of 7 myocarditic patients with normal RV histology.(ABSTRACT TRUNCATED AT 250 WORDS)

Immunosuppressive treatment for myocarditis and borderline myocarditis in children with ventricular ectopic rhythm

OBJECTIVES

To ascertain the responsiveness to immunosuppressive treatment of myocarditis and borderline myocarditis in children with ventricular ectopic rhythm (that is, all ventricular arrhythmia except benign premature ventricular contractions). To determine the impact of the diagnostic information provided by an endomyocardial biopsy specimen in these patients.

BACKGROUND

The therapeutic value of performing an endomyocardial biopsy in children with ventricular ectopic rhythm is not established. In turn, the treatment of myocarditis with immunosuppressive drugs is also controversial.

METHODS

The case notes and endomyocardial biopsy findings of all children with ventricular ectopic rhythm and a biopsy diagnosis of myocarditis were reviewed.

RESULTS

Ten (14%) of 69 patients with ventricular ectopic rhythm and an anatomically normal heart had histological evidence of myocarditis or borderline myocarditis. Eight patients received corticosteroids and efficacy was judged by regular 24 hour Holter monitoring. Total resolution of arrhythmia was seen in four, improvement in two, and no change in two patients. At follow up (8-39 months, mean 22 months), arrhythmia recurrence was seen in the two patients who showed an improvement but not resolution during treatment. Both received azathioprine with further reduction in ectopy rates. Patients who responded to treatment were symptomatic (six of six patients) at presentation compared with those who did not respond to treatment (none of two patients) who were not symptomatic. Five patients had a repeat biopsy specimen taken which confirmed histological improvement.

CONCLUSIONS

Steroid treatment seems to benefit a subset of children with ventricular ectopic rhythm and a biopsy diagnosis of myocarditis or borderline myocarditis. Because it can identify a treatable cause for the ventricular arrhythmia, endomyocardial biopsy is a valuable investigation in these patients.

Right ventricular outflow tract ventricular tachycardia: detection of previously unrecognized anatomic abnormalities using cine magnetic resonance imaging

OBJECTIVES

This study attempted to determine whether cine magnetic resonance imaging (MRI), because of its unique ability to image the right ventricle, detects abnormalities in patients with right ventricular outflow tract ventricular tachycardia.

BACKGROUND

Right ventricular outflow tract ventricular tachycardia occurs in the absence of apparent structural heart disease.

METHODS

We compared cine MRI scans in 22 patients with right ventricular outflow tract ventricular tachycardia, 16 subjects without structural heart disease and 44 patients with other cardiovascular diseases. Echocardiography was performed in 21 patients with ventricular tachycardia.

RESULTS

All 22 patients with ventricular tachycardia had normal left ventricular function and no evidence of coronary artery disease. Cine MRI revealed right ventricular structural and wall motion abnormalities more often in patients with ventricular tachycardia (21 [95%] of 22) than in normal subjects (2 [12.5%] of 16, p < 0.0001) or patients without arrhythmia (17 [39%] of 44, p < 0.0001). The abnormalities in patients with ventricular tachycardia (fixed focal wall thinning, excavation, decreased systolic thickening) were located in the right ventricular outflow tract, whereas those in patients without arrhythmia were confined to the free wall. Cine MRI demonstrated abnormalities in patients with ventricular tachycardia more often than did echocardiography (21 [95%] of 22 vs. 2 [9%] of 21, respectively, p < 0.0001).

CONCLUSIONS

Right ventricular outflow tract ventricular tachycardia was associated with focal structural and wall motion abnormalities of the right ventricular outflow tract that were detected more often by cine MRI than by other imaging modalities and were not present in patients without arrhythmia or in normal subjects.

Persistence of ventricular arrhythmia after resolution of occult myocarditis in children and young adults

OBJECTIVES

We sought to examine whether resolution of occult myocarditis in children with associated ventricular arrhythmia correlated with the presence of arrhythmia at late follow-up.

BACKGROUND

Complex ventricular arrhythmias have been documented in children with myocarditis. Therapy is aimed at controlling the arrhythmia and any associated ventricular dysfunction. However, no reported studies have documented whether resolution of myocarditis in children is associated with resolution of the associated arrhythmias.

METHODS

We performed a retrospective analysis of 12 patients (mean age 12 years) with myocarditis. Ambulatory electrocardiographic (Holter) monitors were reviewed for ventricular arrhythmias at presentation and follow-up. Patients were assigned to Group I if they received corticosteroids in addition to any antiarrhythmic agents and to Group II if they did not receive steroids. Follow-up endomyocardial biopsy was performed in some patients, and results were analyzed in relation to the presence of arrhythmias at follow-up.

RESULTS

Eleven patients had ventricular tachycardia, and one had multiform couplets. Corticosteroids were given to seven patients (Group I). Follow-up biopsy was performed in seven patients (six received steroids), with resolution of inflammation in all; four of the seven still had ventricular arrhythmias but with improved control. Of the five patients without follow-up biopsy, three had persistent arrhythmia. Absence of inflammation at follow-up biopsy did not correlate with loss of ventricular arrhythmias, and there was no difference between Group I and II patients with respect to resolution of arrhythmia (Fisher exact test, p = 0.70, power 11%).

CONCLUSIONS

Complex ventricular arrhythmias persist after apparent resolution of occult myocarditis in children. Although these arrhythmias are easier to control after such resolution, the patients may require long-term antiarrhythmic therapy.