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PubMed1976

[Use of beta-stimulators in chronic ischemic heart disease with complete atrioventricular block complicated by congestive circulatory insufficiency].

In 23 patients with full atrioventricular block and congestive heart failure developing against the background of chronic ischaemic heart disease Isuprel was injected intravenously at a speed of 1 to 3 muG/min. A positive chronotropic effect of the drug was observed and attributed to the dose employed. Isuprel produced a positive dynamics in the structure of the cardiac cycle in the treated patients. A course of such therapy resulted in a reduction, or even disappearance of the circulatory insufficiency signs in the majority of patients, but sinus rhythm could not be restored in either of them. The noted side effects were typical of beta-stimulators. Two patients developed anginal pains in the zone of the heart when the drug was given intravenously.

Adrenergic beta-Agonists↗
PubMed1992

[Dual-cavity pacing for maximal work capacity in patients with a chronic high-grade atrioventricular block].

Twenty-eight patients with a grade 2 and 3 atrioventricular block and an implanted DDD pacemaker were repeatedly subjected to a bicycle ergometric test with a maximum load of the AV block (VV30), ventricular stimulation (VVI70) and DDD stimulation. The maximum work capacity and maximum heart rate achieved on VVI30 were 92 + xi 38 W and 61 +/- 27/min. The maximum work capacity increased on DDD by 49% while on VVI70 only by 22% (p < 0.00001) and the maximum heart rate increased on DDD by 185%, while on VVI70 only by 41% (p < 0.00001). The authors found a significant correlation between the increment of the maximum work capacity on DDD, as compared with that on VVI70 (d maximum work capacity) and maximum work capacity at VVI70 (r = -0.53, p < 0.01), maximum work capacity on VVI30 (r = -0.437, p > 0.03), maximum heart rate at VVI70 (r = -0.415, p < 0.004) and age (r = 0.56, p < 0.005). The d maximum work capacity was significantly higher in patients without their own ventricular activity during the load on VVI70 (28 +/- 24% vs. 13 +/- 8%, p < 0.05 (in patients who did not attain the upper frequency limit of DDD stimulation (30 +/- 25% vs. 14 +/- 9%, p < 0.004) and in patients above 60 years of age (37 +/- 26% vs. 14 +/- 10%, p < 0.002).

Adolescent↗
PubMed1977

Echocardiographic features of second degree atrioventricular block.

Echocardiographic studies demonstrated abnormalities of motion of the pulmonary valve, the aortic root and valve, the mitral and tricuspid valves, the left ventricle, and the left atrium in two patients with second-degree atrioventricular block. During Wenckebach 3:2 atrioventricular conduction, ventricular beats exhibited alternately long and short periods of systolic opening of the pulmonary and aortic valves and alternately large and small left ventricular stroke volumes. During 4:3 and 3:2 Wenckebach atrioventricular conduction, the left ventricular stroke volume was directly proportional to the preceding end-diastolic volume. During 2:1 atrioventricular conduction, the blocked atrial contractions may produce movements of the left atrial wall, thereby revealing the true atrial rate when the blocked P waves are obscured in the electrocardiogram by their superimposition on preceding T waves.

Adolescent↗
PubMed2002

Transient complete atrioventricular block occurring 1 week after radiofrequency ablation for the treatment of atrioventricular nodal re-entrant tachycardia.

Atrioventricular (AV) block following radiofrequency (RF) ablation for the treatment of AV nodal re-entrant tachycardia (AVNRT) is a rare but serious complication of this procedure. Almost all such cases occur during or immediately after radiofrequencey (RF) energy application, followed by prompt recovery. The present report describes a 22-year-old woman with first-degree AV block on electrocardiography, who developed complete AV block 1 week after RF ablation for the treatment of the uncommon form of AVNRT (slow/slow). The patient's complete AV block persisted for another 1 week before she recovered.

Adult↗
PubMed2006

Cardiac arrhythmias and atrioventricular block in a cohort of asymptomatic individuals without heart disease.

AIMS: To evaluate cardiac arrhythmias and rhythm disturbances on 24 h ambulatory electrocardiographic monitoring in a cohort of asymptomatic healthy individuals with normal clinical examination. METHODS AND RESULTS: 625 asymptomatic healthy individuals, in the age range 15-83 (mean 42, SD 11.9) years; 276 (44.2%) men and 349 (55.8%) women were submitted to 24-hour ambulatory electrocardiographic monitoring. Statistical analysis was performed with likelihood ratio test and automatic backward logistic regression. The frequency of atrial arrhythmias (p < 0.0001; OR 1.059; 95% CI 1.050-1068) and of ventricular arrhythmias (p < 0.0001; OR 1.023; 95% CI 1.017-1.029) increased for each age increase of 1 year; neither atrial nor ventricular arrhythmias demonstrated a statistically significant difference relative to gender. Transient second-degree atrioventricular block (Mobitz I) was observed in 14 (2.2%) individuals and was more frequent in individuals with resting heart rate <60 bpm (p = 0.006; OR 6.7, 95% CI 1.7-25.5). CONCLUSION: The frequency of atrial and ventricular arrhythmias increased with age and did not demonstrate a significant difference relative to gender. Transient atrioventricular block was more frequent in individuals with lower resting heart rate.

Adolescent↗
PubMed2005

Congenital complete atrioventricular block and preexcitation syndrome: a well-matched partner.

A patient who had been previously diagnosed with congenital complete atrioventricular block (CCAVB) twenty years ago developed atrioventricular (AV) conduction through an accessory pathway (AP). With enhanced sympathetic tone (exercise, isoproterenol), 1:1 conduction down the AP occurred. An electrophysiologic study confirmed a suprahissian AV block and the presence of an AP. The AP was located on the left side and posterior. The absence of retrograde conduction through the AP and also a long conduction time were demonstrated.

Adult↗
PubMed1986

Atrioventricular block in low potassium and K dependence of the nodal resting potential.

A progressive conduction block leading to atrioventricular dissociation develops in perfused rabbit hearts within 20-30 min of exposure to Krebs containing 0.5 mM potassium (low K). A decrease in potassium permeability resulting in membrane depolarization (as seen in Purkinje fibers) could be responsible for the loss of excitability in nodal cells. We investigated the K dependence of the resting potential and the long-term effects of low K perfusion on the resting and action potentials of nodal cells in rabbit hearts. The resting potential of atrial, atrionodal, and nodal cells varied by 52, 41, and 34 mV per decade of change in Ko within the range of 5-50 mM K. Hyperpolarization of the resting membrane, a progressive decline in action potential amplitude, and a decrease in maximum rate of rise were observed in nodal fibers when exposed to low K. Loss of propagated activity occurred in the middle node within 20-30 min while the cells remained hyperpolarized. There was no evidence of electrogenic Na extrusion and it seems that the low nodal resting potential results from a high resting PNa/PK permeability ratio. The early decrease in rate of rise in low K probably reflects an increase in K-dependent outward currents, whereas the progressive deterioration and final loss of conducted electrical activity may result from an accumulation of internal Na and Ca overload produced by low K inhibition of the Na pump.

Action Potentials↗
PubMed1998

The signal averaged P wave in atrioventricular block--evidence for abnormal atrial conduction?

The incidence of atrial fibrillation in patients with atrioventricular block (AVB) appears increased over that for the unpaced population even if atrioventricular synchrony is maintained by dual chamber pacing. To assess whether atrial fibrillation in these patients might be due to concurrent abnormality in atrial activation we performed signal averaged P wave (SAPW) recordings in 15 patients with dual chamber pacemakers implanted for AVB and compared the results to those from 21 unpaced controls. The median (range) age was 69 (53-89) years for patients and 60 (51-78) years for controls. Eleven patients and 12 controls were male. All patients were pacing in VDD mode at the time of study. SAPW recordings were obtained using our previously reported selective P wave averaging system. We measured P wave duration after high pass filtering at 40 Hz, the rate of change of P wave voltage over time (spatial velocity) and low and high frequency spectral energy after Fourier transformation of the P wave signal. We found increased P wave duration, mean spatial velocity and lower frequency energy in patients with AVB compared to controls [duration, 144 (5) vs. 134 (2) ms, p<0.05; mean spatial velocity, 5.6 (0.4) vs. 4.6 (0.1) mV/s, p<0.05; energy 20-150 Hz, 57.4 (8.2) vs. 36.3 (2.8) muV2.s, p<0.01. All values mean (SEM)]. These results suggest that the increased incidence of atrial fibrillation in patients paced for AVB may be related to intrinsic abnormalities of atrial activation and not solely to the pacing mode. Ensuring sequential atrioventricular pacing in these patients may not completely abolish the increased incidence of atrial fibrillation.

Aged↗
PubMed1991

[Mycotic aneurysm of the sinus of Valsalva and complete atrioventricular block complicating infectious endocarditis with aortic regurgitation: a case report].

A patient with a mycotic aneurysm of the sinus of Valsalva and heart block secondary to infectious endocarditis was described. This 46-year-old man was admitted to our hospital on May 9, 1990, because of fever and progressive general malaise after extraction of a tooth. Physical examination on admission revealed blood pressure of 98/62 mmHg, pulse rate 96 per min, temperature 37.7 degrees C and respiration 35 per min. Auscultation of the heart revealed a grade 3/6 systolic murmur and a grade 2/6 diastolic murmur at the third left intercostal space. Chest radiograph showed mild cardiomegaly with moderate lung congestion. Electrocardiography revealed the first grade atrioventricular block. Echocardiography demonstrated vegetations on the aortic valve, and perforation of the non-coronary sinus of Valsalva. The prolapsed non-coronary sinus of Valsalva extended into the right atrium. Doppler echocardiography revealed a severe aortic regurgitant jet in the diastolic phase. We diagnosed the patient as having aortic regurgitation with a mycotic aneurysm of the non-coronary sinus of Valsalva due to infectious endocarditis. His condition remained severely ill despite intensive medical treatment. On May 14, 1990, aortic valve replacement and excision of the mycotic aneurysm were performed. The commissural portions of the aortic cusps were heavily thickened and calcified. The mycotic aneurysm was very fragile. During manipulating the mycotic aneurysm, the sinus accidentally perforated into the right atrium. The cardioaortic fistula was closed with a goretex patch. A demand pacemaker was implanted because of postoperative complete atrioventricular block.(ABSTRACT TRUNCATED AT 250 WORDS)

Aneurysm, Infected↗
PubMed2006

Ablation for atrioventricular nodal reentrant tachycardia with a prolonged PR interval during sinus rhythm: the risk of delayed higher-degree atrioventricular block.

INTRODUCTION: Delayed higher-degree atrioventricular (AV) block can develop after slow pathway ablation for AV nodal reentrant tachycardia with a preexisting first-degree AV block. Retrograde fast pathway ablation is considered as an alternative approach for patients with a markedly prolonged PR interval and no demonstrable anterograde fast pathway function at baseline. This study aimed to determine the long-term reliability of AV conduction after retrograde fast pathway ablation in comparison to slow pathway ablation in patients with AV nodal reentrant tachycardia and a first-degree AV block at baseline. METHODS AND RESULTS: Among 43 patients with AV nodal reentrant tachycardia and a prolonged PR interval (defined as >or=200 msec), 10 patients without demonstrable dual pathway physiology underwent ablation of the retrograde fast pathway, and 33 patients with dual pathway physiology underwent slow pathway ablation. Persisting intraprocedural second- or third-degree AV block requiring pacemaker implantation occurred in one patient (10%) after retrograde fast pathway ablation and in one patient (3%) after slow pathway ablation. During the long-term follow-up of 61 +/- 39 months after retrograde fast pathway ablation, no delayed second- or third-degree AV block occurred, and the PR interval remained unchanged (308 +/- 60 msec vs 304 +/- 52 msec). During the follow-up of 37 +/- 25 months after slow pathway ablation, a delayed complete heart block developed in two patients, and a second-degree AV block developed in two patients. Three patients aged 66, 75, and 76 years died suddenly of unknown cause 4, 16, and 48 months following slow pathway ablation, respectively. CONCLUSIONS: Slow pathway ablation was associated with a significant risk of a delayed higher-degree AV block in patients with AV nodal reentrant tachycardia and a prolonged PR interval at baseline. Retrograde fast pathway ablation for patients with a first-degree AV block and no demonstrable dual pathway physiology was associated with a higher intraprocedural risk of complete AV block but did not result in the development of higher-degree AV block during the long-term follow-up of up to 9 years.

Aged↗
PubMed1997

Left ventricular mechanics and geometry in patients with congenital complete atrioventricular block.

BACKGROUND: Radiographic evidence of cardiomegaly is common in patients with congenital complete atrioventricular block (CCAVB). It has been speculated that left ventricular (LV) remodeling and increased stroke volume counteract the bradycardia, but the effects of slow heart rate and atrioventricular asynchrony on LV dimensions, geometry, wall stress, and function have not been examined in detail. METHODS AND RESULTS: Thirty patients with CCAVB without associated congenital heart disease (mean age, 8.5+/-5.3 years; range, 0.2 to 20 years) were included in a cross-sectional two-institution study. Thirty-five echocardiograms were performed using standard techniques. ECG and 24-hour ECG recordings were reviewed. Seven patients did not receive a pacemaker, whereas 23 patients underwent pacemaker implantation after the echocardiogram. Compared with normal control subjects, LV volume (Z score=1.5+/-1.3) and LV mass (Z=1.2+/-1.5) were significantly increased, whereas LV mass-to-volume ratio (1.1+/-0.3) and geometry (short-axis diameter/length ratio=0.65+/-0.09) were normal. LV end-systolic stress (ESS) (a measure of afterload) was normal (Z score=0.2+/-2.3), whereas shortening fraction (Z=3+/-2.9) and velocity of circumferential fiber shortening (VCF) (Z=3+/-3.1) were increased. The relationship between VCF and ESS (a preload-insensitive and afterload-adjusted index of contractility) was increased (Z=2.2+/-2) with only small increase in preload (Z=1.02+/-1.1). Regression analyses showed no significant change over age in LV mass, volume, geometry, loading conditions, or systolic function. Patients who ultimately met criteria for pacemaker implantation did not differ from those who did not in terms of heart rate or LV function but did have increased LV volume (Z score=1.8+/-1.4 versus 0.4+/-0.9, P=.03) and LV mass (Z score=1.7+/-1.2 versus 0.2+/-1.7, P=.001) compared to the unpaced group. CONCLUSIONS: In most patients with CCAVB, the LV was enlarged with normal geometry and enhanced systolic function during the first two decades of life. The degree of LV dilation and enhanced function did not significantly change with age. In patients who ultimately underwent pacemaker implantation LV function did not differ from those who remained unpaced, but evidence of a slightly increased load manifested as increased end-diastolic volume and mass.

Adolescent↗
PubMedDate not supplied

Improvement of left ventricular function after changing the pacing site in a child with isolated congenital complete atrioventricular block and dilated cardiomyopathy.

We report a case of isolated congenital complete atrioventricular block with left ventricular dysfunction after pacemaker implantation that improved after the pacing site was changed. During the neonatal period, a pacemaker wire was implanted on the right ventricular epicardium and pacing was initiated. Decreased ejection fraction and a perfusion defect around the septum on myocardial scintigraphy were observed during follow-up. Induced left bundle branch block was thought to be causing interventricular asynchrony, and the pacing site was change to the left ventricular epicardium. Ejection fraction improved and the perfusion defect resolved. Lead relocation may be useful for left ventricular dysfunction that develops during right ventricular pacing.

Cardiac Pacing, Artificial↗
PubMed2005

Transient complete atrioventricular block associated with herb intake.

We report a case of transient complete atrioventricular block in a 38-year-old man, after intake of a mixture of herbs, intended to aid cigarette smoking cessation. Since all other causes of conduction disturbances were excluded, a side-effect of the herbal remedy was identified as the most likely diagnosis. Given that most patients are unaware of the potential risks of the intake of various herbs, we would urge that their usage be regulated.

Heart Block↗
PubMed1993

Comparison between patients with and without reliable ventricular escape rhythm in the presence of long standing complete atrioventricular block.

The underlying heart rhythm was evaluated in 74 patients with complete atrioventricular block and had a permanent pacemaker implantation. The pacing was inhibited for 10 seconds or until the patient developed symptoms of presyncope or syncope. Fifty-six patients (74%) had a reliable escape with a mean cycle length of 2010 +/- 596 msec and a mean escape interval of 2335 +/- 971 msec. In 93% of these patients the escape interval was < 4 seconds. The patients without reliable escape (24%), developed symptoms only after a mean of 7153 +/- 1875 msec. The duration of the conduction disorder was longer in the patients without escape and the intraventricular conduction was slower. More patients without escape were treated and antiarrhythmic agents. Forty-eight patients were followed for 1 year and underwent at least two different studies and 13% had different results at different tests. In conclusion, patients without reliable escape have a longer history of conduction disorder, a slower intraventricular conduction, and are frequently treated with antiarrhythmic agents. Even patients with reliable escape occasionally may show a greater pacemaker dependence; therefore, they should also be considered as pacemaker dependent.

Aged↗
PubMed1978

Intermittent atrioventricular block: procainamide administration as a provocative test.

Twelve patients with clinical features suggesting possible intermittent high degree atrioventricular block were studied. All 12 patients had basic 1:1 atrioventricular conduction but nine had an electrocardiographic pattern of bifascicular distal conduction disease (right bundle branch block with left anterior or posterior hemiblock, or left bundle branch block). Intracardiac conduction was assessed by recording of the His bundle electrocardiogram and atrial pacing techniques, before and 20 minutes after intravenous administration of procainamide, in a dose of up to 10 mg/kg. Before procainamide administration, seven of the 12 patients had a prolonged H-V interval (greater than 55 ms). Procainamide administration lengthened the H-V interval in all 12 patients by 5--40 ms. In five patients, procainamide induced second or third degree AV block below the level of the bundle of His. It was concluded that the administration of procainamide may be a useful provocative test of distal conduction in patients with possible intermittent AV block.

Aged↗
PubMed1992

Atrioventricular block during adenosine thallium imaging.

Transient atrioventricular (AV) block has been reported during adenosine thallium imaging. This study examined the predictors and hemodynamic implications in 55 patients who had second- or third-degree AV block (group 1) and compared the results with those in 803 patients who did not have AV block (group 2). There were no significant differences in age, sex, or heart rate at baseline between the two groups. ST segment depression was observed in 25% of patients in group 1 and 16% in group 2 (p = NS). Chest pain occurred in 56% in group 1 and 44% in group 2 (p = NS). Preexisting conduction abnormalities (17% vs 16%) and treatment with digitalis (15% vs 15%) and beta-blockers (31% vs 36%) were similar in the two groups. The results of thallium imaging were abnormal in 66% in group 1 and 67% in group 2 (p = NS). Reversible thallium defects were seen in 51% in group 1 and 52% in group 2 (p = NS). The AV block appeared during the first 2 minutes of infusion in 40 patients (73%) and disappeared despite continuation of infusion in 43 (78%). The heart rate during AV block was 79 +/- 18 beats/min, and the systolic blood pressure was 127 +/- 27 mm Hg. Premature termination of adenosine infusion was required in one patient (2%). Aminophylline was used in 5% in group 1 and 2% in group 2 (p = NS). Thus AV block is transient, occurs during the early minutes of infusion, is not aggravated by digitalis or beta-blocker therapy, can be seen in patients with normal perfusion images, and is often well tolerated.

Adenosine↗
PubMed1978

Electrophysiologic observations in a patient with bradycardia-dependent atrioventricular block.

In a patient with atrioventricular (A-V) block distal to the His bundle (H), 1:1 A-V conduction with right bundle branch block and H-V interval of 70 msec was established with atrial pacing at rates of 120 to 150/min, suggesting that the A-V block was bradycardia-dependent. Advanced second degree A-V block distal to the H deflection occurred with atrial pacing at 160/min after completion of A-V nodal Wenckebach periodicity proximal to the H deflection because of the long H-H encompassing the blocked P wave. Atrial extrastimulus testing coupled with sinus rhythm (with A-V block) demonstrated that critical H1-H2 intervals of less than 545 msec allowed conduction to the ventricles. The H2-V2 interval shortened progressively from 290 to 70 msec with shortening of these critical H1-H2 intervals. Atrial extrastimulus testing coupled with an atrial driven cycle lenght of 500 mesc (with intact A-V conduction) revealed block of the H2 deflection with an H1-H2 interval longer than 540 msec. In conclusion, at critical diastolic intervals, impulses were blocked, creating a state of decreased responsiveness. If a cycle length of subsequent impulses was shorter than the critical diastolic blocking interval, membrane responsiveness gradually improved and conduction resumed. If a cycle length of subsequent impulses was longer than the critical blocking diastolic interval, A-V block was sustained. Blocked impulses continually penetrated to the site of block and reset the state of membrane responsiveness.

Atrioventricular Node↗