Artificial pacing in management of complete heart block complicating acute myocaerdial infarction

Refractory hypertensive emergency associated with complete heart block resolved after permanent pacemaker implantation: A case report

Severe hypertension sometimes improves with treatment of bradycardia but this phenomenon is under‐reported. Here, an elderly gentleman with complete heart block and a hypertensive emergency was refractory to medical therapies and blood pressure only improved following pacemaker implantation. We discuss the possible mechanisms relating to heart rate and artificial pacing.

Prognosis of acute myocardial infarction complicated by complete heart block (the Worcester Heart Attack Study)

As part of a community-based study of patients hospitalized with acute myocardial infarction (AMI) in the Worcester, Massachusetts, metropolitan area, changes over time in the incidence rates of complete heart block (CHB) complicating AMI, and the prognostic impact of CHB on the in-hospital and long-term survival of these patients were examined. In all, 4,762 patients with validated AMI hospitalized at 16 hospitals in the Worcester metropolitan area during 1975, 1978, 1981, 1984, 1986 and 1988 constituted the study sample. The incidence rates of CHB complicating AMI remained relatively stable at 5.8% over the 13-year (1975 to 1988) period studied. The incidence rates of CHB were approximately twice as high in patients with inferior/posterior wall AMI (7.7%) as in those with anterior wall AMI (3.9%). Use of a multivariate regression analysis to control for factors affecting the incidence rates of CHB revealed that patients were at highest risk for developing CHB during the latter 2 study years (1986 and 1988). Patients with AMI developing CHB had higher in-hospital case fatality rates than did those without CHB overall, as well as during each of the 6 periods studied. The in-hospital survival associated with CHB did not improve over time. After use of a multivariate regression analysis to control for additional prognostic factors, the independent effect of CHB on in-hospital prognosis remained (adjusted risk of dying = 2.10; 95% confidence intervals = 1.37, 3.21). Patients with inferior wall AMI complicated by CHB were at significantly increased risk of dying during hospitalization compared with those without CHB (adjusted risk of dying = 2.71; 95% confidence intervals = 1.60, 4.59).(ABSTRACT TRUNCATED AT 250 WORDS)

Hemodynamic effects of different temporary pacing modes for the management of bradycardias complicating acute myocardial infarction

Twelve patients requiring temporary pacing following acute myocardial infarction (AMI) (10 heart block, 2 junctional bradycardia) had hemodynamic measurements taken with ventricular demand pacing at 80 ppm (VVI80), ventricular demand pacing at the atrial rate (VVIa), physiological pacing (DDD), and spontaneous (intrinsic) rhythm. VVI80 mode did not improve any hemodynamic parameter compared with spontaneous rhythm. VVIa mode improved diastolic and mean arterial pressures only. DDD mode improved most hemodynamic parameters compared with spontaneous rhythm (cardiac output by 29% [P less than 0.0001]; blood pressure: diastolic by 24% [P less than 0.01], systolic by 19% [P less than 0.01], mean by 21% [P less than 0.005]; pulmonary wedge pressure by 10% [P = 0.057] and right atrial pressure by 24% [P less than 0.005]) and also significantly improved some parameters compared with VVIa (cardiac output by 20% [P less than 0.001], systolic blood pressure by 11% [P less than 0.01] and right atrial pressure by 15% [P less than 0.01]). Physiological pacing is hemodynamically superior both to ventricular pacing and spontaneous rhythm for patients requiring temporary pacing following AMI. Ventricular pacing at 80 ppm has little hemodynamic advantage over spontaneous rhythm.

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.

Temporary transvenous cardiac pacing: 6 years experience in one coronary care unit

The role of temporary percutaneous endocardial pacing has been examined in a retrospective analysis of all paced patients admitted to one coronary care unit over a 6 year period. The majority of 162 cases (84.6%) were paced for complete heart block complicating acute myocardial infarction. These patients had a higher incidence of previous hypertension, myocardial infarction and diabetes, compared to matched controls (P less than 0.05, less than 0.02 and less than 0.001, respectively). Admission blood glucose levels were also higher (P less than 0.05). The in-hospital mortality was high (46.7%), especially for those with anterior myocardial infarction (74.5%). Twenty-five (15.4%) patients without recent myocardial infarction were paced for symptomatic brady-dysrhythmias, usually due to chronic complete heart block (Lenegre's disease) or sick sinus syndrome. Most later required permanent pacing. Complications of temporary pacing were more frequent in those who died, the most common being dysrhythmias during pacemaker insertion. Review of our cases suggests that whilst facilities for temporary pacing were extremely valuable, many cases treated were not haemodynamically compromised and probably did not require pacing. Guidelines should be established on coronary care units to prevent the unnecessary morbidity, mortality and expense of the procedure.

Long-term outcome in patients with inferior myocardial infarction and complete atrioventricular block

Some studies have reported increased short-term mortality and higher incidence of multivessel coronary artery disease in patients with inferior myocardial infarction and complete heart block, but information is lacking on clinical outcome after hospital discharge. Therefore, data were obtained and analyzed in 749 patients who were admitted with inferior myocardial infarction to four different centers and followed up for 1 year. Six hundred fifty-four patients (Group 1) did not have complete heart block and 95 (Group 2) had complete heart block during their hospital stay (incidence rate 12.8%). Compared with Group 1, Group 2 patients were older (66 versus 61 years, p less than 0.01), more often had signs of left ventricular failure (p less than 0.001) and had higher peak creatine kinase values (1,840 versus 1,322 IU/liter, p less than 0.001). The in-hospital mortality rate was higher in Group 2 than in Group 1 (24.2 versus 6.3%, p less than 0.001). However, at discharge there was no difference between Group 1 and Group 2 in clinical characteristics, left ventricular ejection fraction (0.52 +/- 0.12 versus 0.52 +/- 0.11) or incidence of complex ventricular arrhythmias on ambulatory electrocardiographic monitoring. Furthermore, during the year after hospital discharge, patients in Groups 1 and 2 did not have significantly different mortality rates (6.4 versus 10.1%, p = NS). The incidence rate of reinfarction (4%) was the same in Groups 1 and 2. The incidence of coronary artery bypass surgery was slightly but not significantly higher in Group 1 compared with Group 2 (11 versus 4%).(ABSTRACT TRUNCATED AT 250 WORDS)

Placement accuracy of percutaneous transthoracic pacemakers

Experience has shown that the frequency of electrical capture of the heart with percutaneous transthoracic pacemakers is disappointingly low. The authors sought to determine whether the accuracy of ventricular placement could help to explain this observation. Six approaches were used in each of twenty adult patients who were examined at autopsy. Three parasternal approaches used the fifth intercostal space (5ICS). One pacing wire was inserted immediately to the left of the sternum along the parasternal line (5ICS-PS), one wire was inserted 4.0 cm to the left of the midsternal line (5ICS-4), and the third wire was inserted 6.0 cm to the left of the midsternal line (5ICS-6). All parasternal needle insertions were directed medially, dorsally, and cephalad toward the second right costrochondral junction at an angle of 30 degrees to the skin. Three subxiphoid approaches were performed through the left xyphocostal notch at an angle of 30 degrees to the skin. One pacing wire was directed toward the right shoulder (SXRS), one toward the sternal notch (SXSN) and one toward the left shoulder (SXLS). Accuracy of ventricular placement was assessed at autopsy. The success rates for the three parasternal approaches were as follows: 5ICS-PS = 0.85; 5ICS-4 = 0.80; 5ICS-6 = 0.90. For the three subxiphoid approaches success rates were as follows: SXRS = 0.25; SXSN = 0.50; SXLS = 0.65. All three parasternal approaches had higher success rates than the SXRS approach (P less than 0.05). In addition, the 5ICS-PS and 5ICS-6 approaches were more successful than the SXSN approach (P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Injuries associated with percutaneous placement of transthoracic pacemakers

Injuries associated with the percutaneous placement of transthoracic pacemakers are poorly documented. We prospectively sought to determine any injuries associated with various placement routes. Six different approaches were used in each of 20 adult patients examined at autopsy. Three parasternal approaches utilized the fifth intercostal space (5ICS). One pacing wire was inserted immediately to the left of the sternum along the parasternal line (5ICS-PS), one pacing wire was inserted 4 cm to the left of the midsternal line (5ICS-4), and the third wire was inserted 6 cm from the midsternal line (5ICS-6). All parasternal needle insertions were directed medially, dorsally, and cephalad toward the right second costochondral junction at an angle of 30 degrees to the skin. Three subxiphoid approaches were inserted through the left xyphocostal notch at an angle of 30 degrees to the skin. One pacing wire was directed toward the right shoulder, one toward the sternal notch, and one toward the left shoulder (SXLS). Injuries were assessed by autopsy, postmortem coronary angiography, and stereoscopic radiography. The 5ICS-PS approach resulted in fewer injuries when compared to all other approaches. Because previous work has demonstrated that the 5ICS-PS, 5ICS-6, and SXLS approaches are more accurate than the other approaches for transthoracic pacemaker insertion, the 5ICS-PS represents an approach that combines reasonable accuracy with the least likelihood for injury in the placement of percutaneous transthoracic pacing wires.

Immediate transthoracic pacing for cardiac asystole in an emergency department setting

This study was conducted to prospectively evaluate immediate transthoracic pacing in the emergency department for cardiac arrest patients presenting with asystole. All adult patients presenting over an 11-month period to a university teaching hospital with asystole following nontraumatic cardiopulmonary arrest received immediate transthoracic cardiac pacing. In these 48 patients, electrical capture was achieved in 23% and mechanical capture in 17%. With subsequent intraventricular administration of epinephrine and sodium bicarbonate, the percentage of responders increased to 48% and 33%, respectively. This is a statistically significant improvement in both electrical and mechanical capture rates (P less than 0.001) as compared with historical controls in whom transthoracic pacemakers were employed several minutes into the resuscitation. In mechanical responders, blood pressure never exceeded 50 mm Hg and could not be sustained for over 2 minutes. Immediate transthoracic pacing was temporarily effective at restoring myocardial electrical and mechanical activity in a substantial number of asystolic patients. Although there were no survivors, the improved electrical and mechanical capture rates with early use of transthoracic pacing is encouraging. Future studies of transthoracic pacing in the prehospital setting appear warranted.

Developments in transcutaneous and transthoracic pacing during bradyasystolic arrest

Transthoracic cardiac pacing historically has been relegated to the role of the technique of last resort in treating cardiac arrest. Recent studies have shown that this technique has a high rate of successful electrical capture, but often without mechanical activity. Survival rates have been shown to be dismal when the technique is used late in cardiac arrest. Results of several recent studies of patients paced by the transcutaneous technique have suggested that electrical capture can often be rapidly obtained in asystolic or pulseless bradycardic patients. Even though electrical capture can occur late in a cardiac arrest, the development of mechanical activity with survival is rare. Survivors generally have been treated early in their arrest and have had hemodynamically ineffective bradycardias. These findings suggest that rapid initiation of transcutaneous pacing in patients with Stokes-Adams attacks, increasing heart block associated with myocardial ischemia, postdefibrillation asystole, or pulseless bradycardia may improve survival. However, victims of a prolonged cardiac arrest whose myocardium has irreversibly ceased to function mechanically are unlikely to benefit from any pacing technique.

Experience of temporary cardiac pacing in a district general hospital

Temporary cardiac pacing is widely used in the management of dysrhythmias; increasingly it is being employed in district general hospitals without specialist cardiology facilities. A retrospective study of 117 pacing procedures in a district hospital has shown that temporary pacing is both safe and effective and supports its more widespread use.

Ventricular fibrillation complicating temporary ventricular pacing in acute myocardial infarction: significance of right ventricular infarction

Five patients with acute myocardial infarction had ventricular fibrillation as a complication of indicated temporary pacing. All five patients had evidence of right ventricular infarction (three patients with postmortem confirmation). The presence of right ventricular infarction seems to be a contributing mechanism involved in the induction of ventricular fibrillation during temporary pacing for bradyarrhythmia complicating acute myocardial infarction.

Complete heart block complicating acute myocardial infarction

Complete heart block (CHB) developed in 10.3% of patients with acute myocardial infarction (MI). It was more frequent among patients with inferior myocardial infarction compared to anterior myocardial infarction, but the mortality was significantly high among patients with anterior MI who developed CHB. A new classification into primary (P) and secondary (S) CHB is suggested by the sequence of events. The incidence and mortality of SCHB was significantly high when compared to the incidence and mortality of PCHB. Wide QRS complexes, a heart rate of less than 60/min, and syncopal attacks were the grave prognostic signs. Progression from a lesser degree of AV block and regression of CHB to a lesser degree of AV Block were both observed in 25.8% cases. Circulatory failure in the form of shock, hypotension, congestive heart failure, and left ventricular failure, alone or in combination was a factor in 17 of the 22 patients who died. Four of 5 patients who underwent transvenous pacing also died.

The clinical significance of bundle branch block complicating acute myocardial infarction. 2. Indications for temporary and permanent pacemaker insertion

The indication for prophylactic temporary and permanent pacing during acute myocardial infarction (MI) complicated by bundle branch block is high risk of progression via a Type II pattern to second or third degree (high degree) AV block during hospitalization or follow-up. In this study, determinants of high degree AV block during hospitalization and sudden death or recurrent high degree block during the first year of follow-up were examined in 432 patients with MI and bundle branch block. Timing of onset of bundle branch block, the involved fascicles, and the PR interval were examined as determinants of risk of progression to high degree AV block during MI. At highest risk were 186 patients with blocks involving the right bundle and at least one fascicle of the left bundle which were not documented on prior electrocardiograms. Risk was similar with (38%) or without (31%) accompanying first degree AV block. Patients with transient high degree AV block during MI had a 28% incidence of sudden death or recurrent high degree block during the first year of follow-up. Patients not continuously paced had a higher incidence of sudden death or recurrent high degree block than patients continuously paced (65% vs 10%, P less than 0.001). Sudden death during follow-up also occurred in 13% of patients without high degree block during MI. A subgroup with 1) documented prior MI, 2) anterior or indeterminant acute MI, and 3) no symptoms of cardiac failure had a 35% risk of sudden death. The role of permanent pacing in this group is unknown. Thus, patients at high risk of high degree AV block should receive prophylactic temporary pacing. Patients who survive high degree block with MI should receive temporary and then permanent pacing. Patients without high degree AV block during MI who nervertheless have a high risk of sudden death may benefit from permanent pacing.

Heart block complicating acute inferior wall myocardial infarction

Heart block was noted in 60 (35 complete and 25 second-degree) of 410 patients with acute inferior wall myocardial infarction. This group with heart block was compared to a control group of 30 patients with acute inferior wall infarction without heart block. The incidences of prior myocardial infarction and hypertension, in addition to the highest level of serum creatine phosphokinase and a maximum degree of ST-segment elevation in the inferior leads, were all greater in patients with heart block, as compared to the controls. The incidences of various complications, including dizziness and syncope, transient hypotension, cardiogenic shock, and congestive heart failure, were also higher in the group with heart block, while sinus nodal distrubances and atrial arrhythmias occurred with equal frequency. The mortality in those with heart block was 28 percent compared to 13 percent for the control. It is concluded that patients with heart block complicating acute inferior myocardial infarction have a greater amount of myocardial necrosis, a higher incidence of complications, and a higher mortality. Insertion of a temporary pacemaker should be considered when specific indications are present and not routinely.

Long-term survival of patients with incomplete bundle-branch block complicating acute myocardial infarction

Electrocardiograms and His bundle electrograms were reviewed in 28 patients with incomplete bilateral bundle-branch block complicating acute myocardial infarction. All had a His bundle electrogram at the time of pacemaker insertion; 10 had a second one. Of 23 patients with an initially abnormal HV interval (55 ms or greater), 15 died (65%), while only one died (20%) in the group of 5 with a normal HV interval. This difference is not statistically significant. Sequential His bundle electrograms were done in 6 of the 8 survivors with an initially abnormal HV interval, and 4 showed 10 to 15 ms decrease in HV interval. The disappearance of incomplete bilateral bundle-branch block occurred significantly more often in patients who survived (7 of 12) when compared with those who did not survive (2 of 16) (P less than 0.05). It is concluded that long-term survival is po-sible after incomplete bilateral bundle-branch block complicating acute myocardial infarction. The characteristics of the survivors include an initially normal HV interval, transient incomplete belateral bundle-branch block and a decreasing HV interval if it were initially abnormal.

His bundle electrogram in patients with acute myocardial infarction complicated by atrioventricular or intraventricular conduction disturbances

Seventy-two patients with acute myocardial infarction complicated by atrioventricular or bundle-branch block or a combination of both had His bundle electrogram studies performed during their stay in the coronary care unit. In 19 of the 72 patients a repeat His bundle electrogram was performed before discharge from hospital. These studies demonstrated that 30 of the 32 patients with atrioventricular block and narrow QRS complexes had a block above the origin othe His spike (proximal block). Eleven patients in this group had repeat His bundle electrograms performed before discharge and in 3 patients there was evidence of residual atrioventricular nodal dysfunction. Both the hospital and follow-up mortality in this group was low and there was no evidence to suggest that permanent pacing would benefit these patients. Of the 18 patients with bundle-branch block and a normal PR interval, 9 had prolongation of the HV interval, but there was no difference in mortality in patients with normal or prolonged HV intervals. Twenty-two patients with bundle-branch block also developed atrioventricular block. In 5 of these patients the site of the AV block was proximal and in 14 it was distal, while 3 patients had both proximal and distal block. The hospital mortality in those patients who progressed to second- or third-degree atrioventricular block was considerably higher than in those patients who remained in first-degree atrioventricular block.

Premonitory sign of heart block in acute posterior myocardial infarction

The appearance of the ARS complex in leads V3R and V4R was analysed in a series of 94 patients with acute posterior myocardial infarction. The cases of posterior myocardial infarction with direct signs of injury (ST segment elevation with a rise of 0.5 mm or more of point F and/or QS pattern) in leads V3R and/or V4R were complicated three times as often by atrioventricular block as those in which such signs were absent (66% and 22%, respectively; P smaller than 0.001). When one of these signs was present in leads V3R and/or V4R, the disorder of conduction was "severe" (complete atrioventricular block or sinotrial block with pauses) in half the cases and "unstable" (bradycardia below 50 beats/min; ventricular pause with or without syncope; widening of QRS complex; ventricular hyperexcitability) in one-third, justifying the introduction of a stimulating catheter. Such disorders were found, respectively, only 1 in 7 (14%), and less than 1 in 10 (8%) when these signs were absent (P smaller than 0.001). The association of ST segment elevation and QS pattern was rarer (15 cases) than the isolated finding of either sign. It was found in the most severe disorders of atrioventricular conduction. The changes observed in leads V3R and/or V4R before the appearance of atrioventricular block enable one to predict which patients with posterior myocardial infarction are the most likely to develop atrioventricular block. These electrocardiographic features seem to indicate septal involvement.

Significance of high degree atrioventricular block in acute posterior myocardial infarction. The importance of clinical setting and mechanism of block

This report evaluates the morbidity and mortality, during hospitalization and follow-up, of a subgroup of patients with posterior or diaphragmatic myocardial infarction (PDMI) who developed high degree A-V block via a type I mechanism and in the absence of power failure (pulmonary edema or cardiogenic shock). This subgroup was not at any higher risk of hospital morbidity, hospital mortality, or 1-year mortality than three other groups: (a) patients with PDMI but neither high degree A-V block nor initial power failure; (b) patients with other infarct sites who developed high degree A-V block in the absence of power failure; and (c) patients with other infarct sites but neither high degree A-V block nor initial power failure. The significance of subgrouping patients with high degree A-V block by the quantity of clinical heart failure is exemplified by a review of the literature and the present study.

Results of early mobilization and discharge after myocardial infarction

A total of 342 patients with acute myocardial infarction who were admitted to a coronary care unit are reviewed to assess the results of early mobilization and discharge. The mean duration of admission was 8.4 days and 89% of the survivors were discharged from hospital by the tenth day. The inpatient mortality was 15.5%. An additional 6.7% died during the six weeks' follow-up period, giving a total mortality of 22.2%. Altogether, 7.6% of patients were readmitted. Venous thromboembolic phenomena occurred in 3.5% during the inpatient period. Of patients who were eligible 62% were back at work five months after their myocardial infarction. We think the results justify a short hospital admission period for acute myocardial infarction.

Implanted-pacemaker-induced dysrhythmia and its management

Five cases of implanted-pacemaker-induced dysrhythmia are described and factors precipitating such dysrhythmias are discussed.

The efficacy of practolol in the treatment of such dysrhythmias is shown and its use as a prophylactic antidysrhythmic agent has been suggested.

Normal blood supply to the human His bundle and proximal bundle branches

The three major coronary arteries of 10 normal human hearts were injected with differentially colored gelatin mass for histologic determination of the blood supply to the His bundle and proximal bundle branches. The His bundle was dually supplied by the A-V node artery and the first septal branch of the left anterior descending artery in nine hearts, but entirely by the A-V node artery in one. The proximal right bundle branch was supplied by both the A-V node artery and septal branch in five hearts, only the septal branch in four, and the A-V node artery alone in one. The anterior half of the left bundle branch was dually supplied by the A-V node artery and septal branch in four hearts, entirely by the septal branch in five, and the A-V node artery alone in one. The posterior half of the left bundle branch was supplied by the A-V node artery alone in five hearts, dually by the A-V node artery and septal branch in four, and by the septal branch alone in one. The blood supply to most of the human His bundle and its proximal branches is thus dual in origin, with anastomosis principally within the His bundle.

Glucagon in heart failure and in cardiogenic shock. Experience in 50 patients

Intravenous glucagon, in doses of 2.5-15 mg/hour, was administered to 50 patients for periods of 1-7 days. Forty patients had either intractable heart failure or cardiogenic shock or both; the remaining 10 had less severe heart disease. In all patients glucagon was added to conventional therapy. Twenty-two of the 40 with very severe heart failure showed a clinical improvement, and 18 were discharged from the hospital; 16 of the 18 patients who did not respond died in the hospital. Only two of the 10 with less severe heart disease improved with glucagon but all could be discharged from the hospital. Glucagon did not initiate or aggravate a tendency to arrhythmias in any of the 17 patients with acute myocardial infarction. In two patients with bradycardia and cardiac failure due to beta-adrenergic blocking drugs, glucagon increased heart rate and there was clinical improvement in heart failure. However, there was no effect in two patients with digitalis-induced nodal bradycardia and heart failure. Nausea was the most troublesome side effect and this could usually be controlled by intramuscular prochlorperazine (Stemetil) which was given routinely before the infusion in all except postoperative patients and repeated as required during the infusion. The results show that glucagon has a definite place in the management of patients with severe heart failure when used as an adjunct to conventional therapy.