Role of myocardial interstitial edema in conduction disturbances in acute myocarditis

Abstract

The presence of myocardial interstitial edema in acute myocarditis (AM) leads to thickening of the ventricular wall, and conduction disturbances, such as complete atrioventricular block (CAV), also frequently develop. This study was undertaken in order to clarify the relationship between conduction disturbances and myocardial interstitial edema in AM. The subjects comprised 50 patients with acute lymphocytic myocarditis. Based on the results of echocardiographic examinations during the acute stage, the patients were divided into a hypertrophy group (n = 29) in which the sum of the thickness of the interventricular septum and left ventricular (LV) posterior wall was >or=24 mm, and a non-hypertrophy group (n = 21) in which the sum of these parameters was <24 mm. Right ventricular endomyocardial biopsies were performed in the acute stage and the degree of interstitial edema was scored histologically. Left ventricular wall thickness and QRS duration in the acute stage were 27.7 +/- 3.6 mm and 124.1 +/- 29.6 ms, respectively, in the hypertrophy group, and 19.9 +/- 2.4 mm (P < 0.001) and 98.6 +/- 21.7 ms (P < 0.01) in the non-hypertrophy group. Complete atrioventricular block was found in 13 of 29 cases (45%) in the hypertrophy group and two of 21 cases (10%) in the non-hypertrophy group (P < 0.01). Myocardial interstitial edema was scored at 1.3 +/- 0.8 points in the hypertrophy group and 0.8 +/- 0.6 points in the non-hypertrophy group (P < 0.05). Left ventricular wall thickness and QRS duration in the convalescent stage decreased to 21.1 +/- 2.6 mm (P < 0.0001) and 97.1 +/- 17.4 ms (P < 0.01) in the hypertrophy group, respectively. Only one case (4%) in the hypertrophy group continued to show CAV during the convalescent stage (P < 0.05). The results of this study suggest that myocardial interstitial edema is implicated in the conduction disturbances that occur in AM.

Cardiac Magnetic Resonance Assessment of Myocarditis

“…With respect to myocarditis, however, typically echocardiography findings do not allow for diagnosing myocarditis. 5 The scant published evidence for echocardiography findings in myocarditis includes increased wall thickness and hyperechogenicity, often accompanied by conduction abnormalities 6 ; yet, both are not frequently observed in clinical routine. This may be, in part, related to technical factors (such as the acoustic window) and physician-related factors (experience, low index of suspicion).…”

Seizures and Syncope Due to Complete Atrioventricular Block in a Patient with Acute Myocarditis with a Normal Left Ventricular Systolic Function

“…However, their patient had fulminant myocarditis, persistent complete AV block and a recurrence of myocarditis. Previous studies on the clinical and experimental histopathology of myocarditis suggest that myocardial interstitial edema and neural tissue damage are implicated in the transient conduction disturbances of acute myocarditis (20,21). This suggests that transient complete AV block occurring in patients with acute myocarditis, as in our case, can develop even in the absence of severe myocarditis and has the potential to cause direct damage to the AV conduction system.…”

Cardiogenic Shock due to Left Ventricular Outflow Obstruction and Complete Atrioventricular Block in a Patient with Hypertrophic Cardiomyopathy with Acute Myocarditis

“…Histopathological studies in previous cases suggested that myocardial edema is mainly responsible for the transient complete AV block in acute myocarditis (14). Although transient complete AV block was often seen in patients with acute myocarditis in previous reports, persistent AV block occurs in only 22-28% of patients with acute myocarditis with complete AV block (15,16).…”