Pseudo 2:1 atrioventricular block and T wave alternans in the long QT syndromes

The extreme prolongation of ventricular action potential duration that occurs in some of the long QT syndromes may result in two forms of alternating activity of the heart: a "pseudo" 2:1 atrioventricular (AV) block and a T wave alternation, both of which are rate dependent. The pseudo 2:1 AV block relates to the extreme prolongation of ventricular refractoriness. The T wave alternation reflects the fact that the rate dependence of action potential duration differs in degree or magnitude in the subendocardial and subepicardial layers of the ventricular wall. Examples of two cases previously reported in the Journal by Weintraub et al. are used to illustrate and discuss these manifestations.     

Bedside recognition,incidence and clinical course of right ventricular infarction

To evaluate the incidence, clinical characteristics and course of right ventricular infarction, 96 patients with an established diagnosis of acute myocardial infarction were evaluated during a 10 month study period. Of the 44 patients with acute inferior wall myocardial infarction, 16 had bedside evidence of right ventricular dysfunction. All had a positive Kussmaul's sign, and 12 had either a right ventricular third or fourth heart sound. Inspiratory elevation of right atrial and right ventricular end-diastolic pressures was documented in nine patients. Ventricular fibrillation developed in one patient and advanced atrioventricular block in three. All 16 patients survived and were alive 3 months after infarction. The hospital course and 3 month survival rate were not different from those of the usual patient with inferior wall infarction. Approximately one third of the patients with inferior wall myocardial infarction have bedside evidence of right ventricular infarction, which usually does not alter short-term prognosis.     

Right ventricular involvement with acute inferior wall myocardial infarction identifies high risk of developing atrioventricular nodal conduction disturbances

In 67 consecutive patients with inferior wall acute myocardial infarction (AMI), 99m-technetium pyrophosphate scintigraphy was performed 36 to 72 hours after the onset of chest pain to detect right ventricular (RV) involvement. All patients were continuously monitored during at least 3 days to detect rhythm and conduction disturbances. In 29 patients RV involvement was diagnosed by scintigraphy. None of these 29 patients showed clinical signs of right-sided heart failure. Fourteen of the 19 patients showing atrioventricular (AV) nodal condution disturbances in the setting of inferior AMI also had RV involvement. Therefore, the incidence of high-degree AV nodal block in patients with RV involvement (14 of 29 patients) was 48% compared to only 13% (5 of 38) in patients with inferior AMI without RV involvement.     

Prognostic significance of complete atrioventricular block in patients with acute inferior myocardial infarction with and without right ventricular involvement

Data were obtained and analyzed in 243 patients with acute inferior myocardial infarction who were admitted to the coronary care unit during the years 1987 and 1988. One hundred and ninety-eight patients had no signs of right ventricular involvement (group I), whereas 45 patients had inferior myocardial infarction with right ventricular infarction (group II). Patients were divided into groups depending on the presence or absence of complete atrioventricular block during hospital stay (groups Ia and IIa without block and groups Ib and IIb with block). Selected clinical and laboratory variables were compared for each group. We found that patients with inferior myocardial infarction and complete atrioventricular block had significantly higher mortality rates only in the presence of right ventricular infarction: 41% mortality rate in group IIb versus 11% mortality rate in group Ib (p less than 0.05). Patients with right ventricular infarction but without complete atrioventricular block (group IIa) had a mortality rate similar to that found in patients with inferior myocardial infarction and no atrioventricular block (group Ia): 14% versus 11% (p = NS). In patients with inferior myocardial infarction without right ventricular involvement (group I), complete atrioventricular block did not influence survival: 14% mortality rate in group Ib versus 11% mortality rate in group Ia (p = NS). The excessively high mortality rate in patients who have inferior myocardial infarction with right ventricular involvement and complete atrioventricular block could be the consequence of greater infarct size, but the synergistic influence of right ventricular infarction and complete atrioventricular block could be the other factor that influences outcome.     

Combined bipolar dual chamber pacing and automatic implantable cardioverter/defibrillator

A 67 year old man with recurrent hypotensive ventricular tachycardia, amiodarone-induced bradyarrhythmias and severe cardiac dysfunction underwent simultaneous implantation of an automatic cardioverter/defibrillator and bipolar atrioventricular (AV) pacemaker. The pacing electrodes were placed epicardially near the right atrial appendage and on the lateral right ventricular wall. The rate detector of the automatic defibrillator was placed epicardially on the posterobasal left ventricular wall. Effective bipolar AV pacing produced no false counting of the heart rate by the automatic cardioverter/defibrillator, and ventricular tachycardia properly inhibited the pacemaker. Long-term follow-up study confirmed the safety of this treatment. With proper precautions, bipolar AV pacing can be safely combined with an automatic cardioverter/defibrillator.     

Left and right ventricular function in inferior acute myocardial infarction and significance of advanced atrioventricular block

Of 139 consecutive patients with a first inferior acute myocardial infarction, 26 (19%) had advanced atrioventricular (AV) block and 113 (81%) did not. All were evaluated by 2-dimensional echocardiography (2-D echo) and radionuclide angiography. Patients with advanced AV block had lower radionuclide left ventricular (LV) ejection fraction (51 +/- 10 vs 58 +/- 11%, p less than 0.01), higher LV wall motion score on 2-D echo (5.6 +/- 2.6 vs 3.1 +/- 2.7, p less than 0.001), lower radionuclide right ventricular (RV) ejection fraction (32 +/- 15 vs 39 +/- 16%, p less than 0.001) and higher RV wall motion score on 2-D echo (3.4 +/- 1.7 vs 1.5 +/- 2, p less than 0.002) than did patients without AV block. The incidence rate of RV dysfunction was higher in patients with advanced AV block (78 vs 40%, p less than 0.02), and the mortality rate was also higher (although not significantly) in patients with advanced AV block (15 vs 6%). In conclusion, patients with inferior acute myocardial infarction and advanced AV block have larger infarct sizes (as seen on radionuclide angiography and 2-D echo) and lower RV and LV function than patients without AV block. This finding may explain the higher mortality rate observed in this group.     

RIGHT VENTRICULAR INFARCTION, BRADYARRHYTHMIAS, AND CARDIOGENIC SHOCK: IMPORTANCE OF ATRIAL OR ATRIOVENTRICULAR SEQUENTIAL PACING

Abstract: :We report two patients with inferior myocardial infarction, complicated by bradyarrhythmia, hypotension, and clinical evidence of right ventricular infarction. Conventional therapy of volume expansion and inotropic support was insufficient to maintain an adequate blood pressure. Sequential atrioventricular (AV) pacing for AV block (Case 1) or atrial pacing for junctional bradycardia (Case 2) resulted in immediate and sustained improvement in blood pressure and clinical indices of perfusion. We recommend consideration of these pacing modes in patients with inferior infarction with evidence of right ventricular infarction, bradyarrhythmia, and cardiogenic shock. The likely mechanism of improvement is by restoration of atrial transport with consequent improvement in ventricular function.     

Idiopathic recurrent sustained ventricular tachycardia responsive to verapamil

The role of i.v. verapamil in the management of atrioventricular (AV) nodal reentrant tachycardias is well established (Schamroth et al., 1980). Generally however the drug is not very effective in recurrent ventricular tachycardia (VT) (Singh et al., 1983). Verapamil was recently demonstrated to be successful in terminating VT induced by programmed stimulation in only 1 out of 8 patients tested (Wellens et al., 1980). Conversely a few recent cases of verapamil responsive VT, mostly occurring in young people without obvious organic heart disease, have been reported (Belhassen, 1984; Klein, 1984; Delise, 1985; Ward, 1984; Lin 1983; German, 1983; Mason, 1983; Wu, 1981). We describe 3 clinical examples of idiopathic recurrent sustained VT responsive to verapamil. A careful analysis of our cases support the hypothesis of different pathophysiologic mechanism involved in the genesis of this unique arrhythmic entity.     

Duration of complete atrioventricular block complicating inferior wall infarction treated with fibrinolysis

INTRODUCTION AND OBJECTIVES: The aim of this study was to determine the duration of complete atrioventricular block complicating inferior wall acute myocardial infarction after the administration of fibrinolytic therapy. PATIENTS AND METHOD: From 1 January 1992 to 31 January 2002 a total of 449 patients were admitted directly to our hospital with inferior wall acute myocardial infarction in the first 6 hours; 282 of them (64%) received fibrinolytic therapy. Complete atrioventricular block appeared in 39 of these 282 patients (13.8%, group A). Of the 167 patients who did not receive thrombolytic therapy, complete atrioventricular block appeared in 13 (8%, control group). We compared the two groups by analyzing the duration of heart block, time to appearance, hemodynamic repercussion, and treatment required. RESULTS: On admission, 38% of the patients in group A and 61% (P=NS) of those in the control group had complete atrioventricular block. Median duration of the block was 75 minutes (10 minutes to 48 hours) in group A and 24 hours (15 minutes to 9 days) in the control group (P=.004). After fibrinolytic therapy was administered, median duration of the block was 45 minutes (5 minutes to 48 hours). A temporary pacemaker was implanted in 43% of the group A patients and 84.6% of the control group patients (P=.01). CONCLUSION: Complete atrioventricular block appears as a complication of inferior myocardial infarction within the first hours after the event. Duration of the block seems to be shorter in patients treated with fibrinolytic therapy.     

Advanced early and late atrioventricular block in acute inferior wall myocardial infarction

Seventy-six patients with acute inferior acute myocardial infarction (AMI) and advanced atrioventricular (AV) block are described. According to pre-established ECG criteria and time of appearance of the advanced AV block, patients were divided into two groups. The early block group consisted of 31 patients who developed advanced AV block during the hyperacute ECG stage of AMI. Advanced AV block in these patients was characterized by early appearance, short duration, third-degree type block, poor response to atropine, and increased need for pacemaker therapy. The late block group consisted of 45 patients who developed advanced AV block during subsequent ECG stages of AMI. Advanced AV block in these patients was characterized by late appearance, longer duration, second-degree type block, positive response to atropine, and diminished need for pacemaker therapy. Morbidity and mortality also differed between both groups. Patients with early block had more syncope (32% vs 2%, p < 0.0001), more left heart failure (36 vs 7%, p < 0.005), and more cardiogenic shock (39% vs 2%, p < 0.001) than patients with late block. The mortality rate in the early block group was high (23%) and similar to that reported in the literature, whereas the mortality rate in the late block group was low (7%, p < 0.05) and similar to the mortality rate reported for acute inferior AMI without advanced AV block. These data identify a subgroup of patients with acute inferior AMI and advanced AV block, which accounts for the high mortality rate reported in this group of patients.     

Right bundle-branch block and left axis deviation in acute myocardial infarction

Of 114 patients with acute myocardial infarction admitted consecutively to a coronary care unit, 10 had recent antero-septal myocardial infarction associated with right bundle-branch block and obvious left axis deviation, and I had recent antero-septal myocardial infarction with right bundle-branch block and right axis deviation. Attention is drawn to the high mortality (7 out of 11 patients), due mainly to cardiogenic shock. Frequent complications were sudden complete heart block (5 patients) and ventricular asystole (4 patients) without previous lengthening of the atrioventricular conduction time. An external on-demand pacemaker was inserted in 10 patients, and no patient died of complete heart block or ventricular asystole.     

Native QRS complex duration predicts paced QRS width in patients with normal left ventricular function and right ventricular pacing for atrioventricular block

Introduction

Prolonged paced QRS duration is a predictor of development of heart failure during chronic right ventricular pacing. One determinant of paced QRS width might be His-Purkinje system dysfunction, manifested in wide native (escape or conducted beat) QRS complexes in patients with atrioventricular (AV) block.

Methods

Fifty patients with normal left ventricular function who are undergoing implantation of a pacemaker for AV block were enrolled. The duration of the QRS complex was measured on the surface electrocardiogram during escape rhythm in 28 patients with total AV block and during conducted beats in 22 patients with second-degree, fixed ratio (2:1 or 3:1) AV block, as well as during ventricular paced rhythm after pacemaker implantation in all patients.

Results

A close, positive correlation was found between native and paced QRS duration in the second-degree AV block group (R = 0.74, P < .001). This association was also significant but less pronounced in the total AV block group (R = 0.46, P = .014).

Conclusion

Native QRS width, especially in case of fixed ratio (2:1 or 3:1) second-degree AV block, is a predictor of paced QRS duration in patients with AV block and normal left ventricular function. Wide QRS complex before implantation may carry a higher risk of developing heart failure with right ventricular pacing.     

Complete atrioventricular block complicating inferior wall acute myocardial infarction treated with reperfusion therapy. TAMI Study Group

Previous studies report larger myocardial infarcts and increased in-hospital mortality rates in patients with inferior wall acute myocardial infarction (AMI) and complete atrioventricular block (AV), but the clinical implications of these complications in patients treated with reperfusion therapy have not been addressed. The clinical course of 373 patients--50 (13%) of whom developed complete AV block--admitted with inferior wall AMI and given thrombolytic therapy within 6 hours of symptom onset was studied. Acute patency rates of the infarct artery after thrombolytic therapy were similar in patients with or without AV block. Ventricular function measured at baseline and before discharge in patients with complete AV block showed a decrement in median ejection fraction (-3.5 vs -0.4%, p = 0.03) and in median regional wall motion (-0.14 vs +0.24 standard deviations/chord, p = 0.05). The reocclusion rate was higher in patients with complete AV block (29 vs 16%, p = 0.03). Patients with complete AV block had more episodes of ventricular fibrillation or tachycardia (36 vs 14%, p less than 0.001), sustained hypotension (36 vs 10%, p less than 0.001), pulmonary edema (12 vs 4%, p = 0.02) and a higher in-hospital mortality rate (20 vs 4%, p less than 0.001), although the mortality rate after hospital discharge was identical (2%) in the 2 groups. Multivariable logistic regression analysis revealed that complete AV block was a strong independent predictor of in-hospital mortality (p = 0.0006). Thus, despite initial successful reperfusion, patients with inferior wall AMI and complete AV block have higher rates of in-hospital complications and mortality.     

Right bundle-branch block and left axis deviation in acute myocardial infarction.

Of 114 patients with acute myocardial infarction admitted consecutively to a coronary care unit, 10 had recent antero-septal myocardial infarction associated with right bundle-branch block and obvious left axis deviation, and I had recent antero-septal myocardial infarction with right bundle-branch block and right axis deviation. Attention is drawn to the high mortality (7 out of 11 patients), due mainly to cardiogenic shock. Frequent complications were sudden complete heart block (5 patients) and ventricular asystole (4 patients) without previous lengthening of the atrioventricular conduction time. An external on-demand pacemaker was inserted in 10 patients, and no patient died of complete heart block or ventricular asystole.     

External cardiac pacing in right ventricular infarction

A patient with acute inferior wall myocardial infarction presented with clinical evidence of right ventricular infarction complicated by bradycardia and cardiogenic shock. Pharmacologic interventions produced no change in heart rate or blood pressure, and a transvenous pacemaker failed to capture the infarcting right ventricle. An external transthoracic pacemaker immediately increased the heart rate with a marked hemodynamic improvement. In the setting of right ventricular infarction, external pacing may be more effective than transvenous pacing, perhaps due to its ability to pace the left ventricle.     

Prognostic significance of second and third degree atrioventricular block in acute inferior wall myocardial infarction

High degree atrioventricular block complicates inferior wall acute myocardial infarction in 10 to 15% of cases. Its significance is still controversial. In this study, we have analysed 152 observations of acute inferior wall myocardial infarction during hospitalisation period. The mean age of our patients is 60 years, 48.7% of them have received fibrinolytic treatment. Second or third degree atrioventricular block was detected in 33 cases (21.7%). Mortality is higher in inferior wall myocardial infarctions with atrioventricular block than in those without atrioventricular block (12% versus 2.5%, p < 0.05). Hemodynamic complications like cardiogenic shock due to the extension of the infarction to the right ventricle and left ventricle insufficiency are more frequent (18% versus 3.4%, p < 0.01 and 12% versus 3.5%, p < 0.01 respectively). It appears that the infracted mass of myocardium is larger in case of atrioventricular block, this is assessed by comparing the average value of the peak of creatine Kinase in the two groups with and without atrioventricular block (1534 IU versus 1096 IU, p < 0.02) and by considering the rate of low ejection fraction (EF < 40%) in each group (44.6% versus 16%, p < 0.01). In our study, we note that thrombolysis does not affect the incidence of atrioventricular block (19% and 24% in thrombolyed and not thrombolyzed patients respectively) but it seems that thrombolysis improves the outcome of these patients. The occurrence of atrioventricular block in acute inferior wall myocardial infarction is related to the presence of an important right coronary artery that is occluded, the recanalisation of this vessel leads often to rapid regression of the block that is no longer pejorative.     

Atrial dissociation. A case of unilateral slow atrial rhythm

Atrial dissociation is a very rare, transient arrhythmia frequently associated with intractable congestive heart failure. A case of atrial dissociation in a 48-year-old woman was observed in the first 72 hours of her recent inferolateral and probably atrial infarction. The slow unilateral rhythm was registered in the presence of sinus rhythm, 2:1 AV block, advanced AV block and ventricular pacemaker stimulation, respectively. The simultaneous right atrial electrogram indicated the origin of the isolated slow rhythm as left atrial. After temporary pacemaker therapy the atrial dissociation disappeared within three days; on the fifth day the normal sinus rhythm was restored spontaneously.     

Subcostal M-mode echocardiography of the right atrial wall in the diagnosis of cardiac arrhythmias

The M-mode echocardiogram of the right atrial (RA) wall can be easily recorded in each person from the subcostal location. In a normal RA wall motion pattern, atrial contraction is represented by a markedly prominent posterior motion. The presence or absence of atrial contractions in the subcostal RA wall echocardiogram, their amplitude, and their timing may help in the diagnosis of cardiac arrhythmias with the simultaneously recorded non-diagnostic electrocardiogram. Flat and hidden P waves can be accurately identified throughout the cardiac cycle. It is possible to distinguish between atrial, ventricular, and nodal premature beats and to recognize atrial fibrillation, atrial flutter, paroxysmal atrial tachycardia, paroxysmal atrial tachycardia with block, atrioventricular (AV) nodal tachycardia, and supraventricular tachycardias with aberrant ventricular conduction. The diagnosis of wandering pacemaker, AV dissociation, sinoatrial block, and AV block is facilitated. On the basis of study of 60 patients with various rhythm disturbances, it was concluded that analysis of the subcostal RA wall echocardiogram is a new, helpful noninvasive approach in the diagnosis of cardiac arrhythmias.     

Quand implanter un stimulateur cardiaque après remplacement valvulaire aortique percutané ? Revue de littérature

Transcatheter aortic valve implantation (TAVI) is nowadays a worldwide technique in the field of treating aortic stenosis. One of the main side effects linked to the technique are mostly attached to rhythm disturbances, such as atrioventricular (AV) and intraventricular blocks. Consequently, a pacemaker implantation is often required. That implantation rate is estimated between 8 and 30%, depending on the valve chosen. Thanks to main meta analysis on the subject, it has been managed to isolate the following risks factors for AV block development: preoperative right bundle branch block (RBBB: the most powerful element), complete AV block during the procedure, male gender, a so-called porcelain aorta, the absence of previous valvular surgery, the aortic annulus size (i.e when that size is inferior to the valve's one) and the QRS duration after the procedure (the superior threshold has been set at 128 ms for the Corevalve). The currently recommendations advice to implant a pacemaker are as followed: high grade AV block (in the main studies, the implantation occurs within the 5 days after the TAVI), complete and transient AV block during the TAVI, second degree AV block and RBBB associated with first degree AV block. Our article aims to review the arrhythmic issues of TAVI.     

心电图J／R比值对下壁心肌梗死并发房室阻滞的预测价值

目的探讨急性下壁心肌梗死早期心电图表现对高度房室阻滞的预测价值以及与冠状动脉病变的关系。方法分析97例急性下壁心肌梗死患者早期心电图（下壁导联）J／R≥0．5的发生情况，部分病例结合冠脉造影结果，探讨其对房室阻滞的预测价值。结果27例（21．6％）在心肌梗死急性期发生二度以上房室阻滞。有房室阻滞者，心电图下壁导联J／R≥0．5多于无房室阻滞者（69．56％vs30．44％，p〈0．01）。冠状动脉造影显示，有房室阻滞者，右冠状动脉近中段的高度狭窄明显多于无房室阻滞者（100％vs58．33％）。结论急性下壁心肌梗死伴房室阻滞者的病损冠脉以右冠状动脉多见，下壁导联心电图J／R≥0．5对下壁心肌梗死合并房室阻滞的发生有一定的预测价值。