Long-term effects of frequent maximal breath-holding on the cardiac health of elite freedivers.

Cardiac arrhythmias are commonly reported in freedivers during maximal voluntary breath-holds, but their influence on the cardiological status and their long-term effects on the cardiac health of these athletes have not been investigated. Here we present the results of a study on 32 healthy young men (mean age 32.6 ± 1.3 years) who were divided into two groups of 16 subjects. One group included 16 continuously training freedivers at the "high achievers in sports" level (DIVERS group). The CONTROL group included 16 healthy young men not involved in sports. The subjects were monitored using 24-h electrocardiogram (ECG), and echocardiological study (EchoCG) for all the subjects was performed. The mean heart rate in the DIVERS group was 69.5 ± 1.7 bpm compared with 70.9 ± 1.5 bpm in the CONTROL group. The minimal heart rate was 42.3 ± 1.0 bpm in the DIVERS group and 48.8 ± 1.7 bpm in the CONTROL group (P < 0.005). The maximal heart rate was 132.8 ± 4.6 bpm in the DIVERS group and 132.1 ± 2.9 bpm in the CONTROL group. ECG analysis revealed supraventricular arrhythmias in the DIVERS group: four of the DIVERS (25%) exhibited supraventricular couplets and triplets, three (19%) exhibited transient first- and second-degree AV blocks (Mobitz type 1) at night, and one (6%) exhibited a second-degree sinoatrial block at night. According to the echocardiogram, the DIVERS had slightly larger left ventricles (5.1 ± 1.33, P < 0.05) and left atriums (41.1 ± 12.7) compared with the CONTROL group without exceeding the normal values. The right ventricle volume (3.6 ± 0.69, P < 0.05) was somewhat above the upper normal value (up to 3.5 cm). In conclusion, freediving athletes exhibited changes in their cardiac status, most likely due to the regular exercise, that were not associated with regular maximal voluntary breath-holds. These changes are within the normal physiological values and do not limit their freediving practice.

Confirmation of the prevalence and importance of a 12-lead investigation for diagnosis of interatrial block [corrected].

We investigated 500 consecutive, unselected electrocardiograms of outpatients for interatrial block (IAB) using all 12 leads rather than the usual recommendation in the literature, which is lead II, sometimes with another lead. IAB had been reported in 2 widely separated large general hospitals in >40% of 1,000 patients in sinus rhythm in each. Because the P waves in IAB (duration > or =110 ms) generally have low amplitude despite their excessive width, we used magnifying graticules and, for greater specificity, a minimal duration of > or =120 ms. Four hundred sixty-nine patients remained after excluding those with atrial arrhythmias or technically poor tracing. Two hundred three of these patients (40.6%) had IAB. Had we used lead II alone, only 110 cases would have been identified, which would have meant overlooking almost 1/2 the cases with this lesion, which is important (1) as a predictor of atrial fibrillation and other arrhythmias, and (2) represents a large, dysfunctional left atrium. Leads V3 and V4 yielded larger numbers of IAB than lead II. (The slightly smaller prevalence than in the 2 cited studies may be due to our using 1/2 the number of patients.) Electrocardiographic interpreters should seek IAB in all 12 leads and consider its anatomic functional and predictive correlates.

Early atrial arrhythmias in acute myocardial infarction. Role of the sinus node artery.

We studied atrial arrhythmias during the first 12 h of admission to the hospital in 266 consecutive patients with acute myocardial infarction who subsequently underwent coronary angiography. Ten patients developed atrial fibrillation, one atrial flutter, and one supraventricular tachycardia. Another five developed sinus dysrhythmias. All of the above patients had an acute inferior myocardial infarction, and in 10 of the 12 patients with supraventricular arrhythmias and in four of five with sinus dysrhythmias, the origin of the sinus node artery started just after an occluded right coronary or left circumflex artery or was involved in the occlusion. Thus, ischemia of the sinus node due to coronary occlusion proximal to the origin of the sinus node artery was a likely cause of these arrhythmias.

Infants with apparent life threatening events. Cardiac rhythm and conduction.

The role of cardiac dysrhythmias in the pathogenesis of Sudden Infant Death Syndrome (SIDS) is uncertain, but there have been several reports of infants with Apparent Life Threatening Events (ALTE) due to significant dysrhythmias. To further characterize the cardiac rhythm and conduction of these "at-risk for SIDS" infants, we performed 24-hour continuous (Holter) electrocardiograms on 100 full term, healthy infants with ALTE. Sixty-two patients (62%) had one or more dysrhythmias on Holter monitor. Twenty-five patients (25%) had premature ventricular depolarizations (PVD), including five with couplets. Thirty (30%) had QTc greater than 2 SD above the mean, and, of these, 40 percent had PVD's. Fifteen (15%) had premature atrial depolarizations and 39 (39%) had evidence of moderate or marked sinus node irregularity. There was no prexcitation, supraventricular tachycardia, ventricular tachycardia, or atrioventricular block. Two patients with marked sinus node dysfunction were treated with propantheline and did well. All patients were monitored at home, with no deaths or clinically significant dysrhythmias on follow-up (1-32 months (mean = 18]. In summary, when Holter monitoring was performed, a high incidence of dysrhythmia was found in infants with ALTE. Most dysrhythmias were clinically insignificant. The incidence of ventricular dysrhythmias and long QTc are consistent with previously advanced theories of cardiac electrical instability in some of these patients, but no patient with ventricular dysrhythmias required therapy. The incidence of sinus node dysfunction requiring therapy was 2 percent. Although Holter monitoring of infants with ALTE only infrequently determines therapy, it may provide data linking theories of cardiac etiology of SIDS with actual clinical events.

[Chronic idiopathic binodal block. Occurrence, course and pathogenesis]. / Le bloc binodal chronique idiopathique. Fréquence, aspects évolutifs et hypothèses pathogéniques.

The incidence of binodal, sinoatrial (SA) and atrioventricular (AV), block was determined in a series of 362 patients, 90 of whom had chronic sinoatrial block (group I), 162 suprahisian, infrahisian or diffuse AV block (group II), 38 with paroxysmal supraventricular tachycardia (group III), and 70 with slow atrial fibrillation, 54 of whom were studied in sinus rhythm (group IV). Electrophysiological investigation revealed: overt or latent AV block in 71% of group I, 48% of group III, and 100% of group IV; overt or latent SA block in 40 to 61% of group II, 87% of group III and 78% of group IV; paroxysmal atrial fibrillation in 61% of group I, 25% of group II and 50% of group IV; intra-atrial block in 26% of group I, 20% of group II, 16% of group III and 31% group IV. An ECG syndrome associating binodal block and disturbances or atrial conduction and excitability is suggested. The pathogenesis and anatomical basis are discussed, the prime lesion of which may be fibrosis of the atrial tissues which may ultimately result in partial or total atrial standstill.

Prevalence of interatrial block in patients with Friedreich's ataxia.

UNLABELLED: Interatrial block is a predictor of atrial arrhythmias. Aim of the present study was to estimate the prevalence of interatrial block (IAB) in Friedreich's Ataxia (FA) compared to controls and correlate it with echocardiographic and genetic features. METHODS: IAB, defined as an electrocardiographic (ECG) derived P-wave duration >120 ms, echocardiographic variables and genetic markers were evaluated in 23 FA patients with no manifestation of cardiac involvement and were compared to 23 sex- and age-matched controls. RESULTS: IAB was significantly more frequent among FA patients compared to controls (11/23 vs 1/23, p<0.005 respectively). However, no correlations with echocardiographic parameters or Guanine-Adenine-Adenine (GAA) trinucleotide repeat lengths could be established. CONCLUSION: Early recognition of IAB could allow the identification of asymptomatic FA patients who are prone to develop potentially life-threatening arrhythmias.

The scoring of cardiac events during sleep.

Standardized guidelines for polysomnography (PSG) have not specified methods for acquiring or interpreting electrocardiographic (ECG) data. The practice of single lead ECG monitoring during PSG may allow identification of simple measures of cardiac rhythm but reduces the ability to detect myocardial ischemia and to define cardiac intervals. Although simple measures of cardiac rhythm such as heart rate and cardiac pauses are inherently reliable, there is limited data regarding outcome measures relative to sleep related heart rates and cardiac events during sleep. Several observational and cross-sectional studies demonstrate that average heart rate drops nearly 50% from infancy through young adulthood and that the average heart rate slows during sleep compared with wakefulness; the definitions of sinus bradycardia and sinus tachycardia should therefore be lower during sleep than wakefulness. Asystoles of up to 2 seconds are seen in normal populations during sleep. Although there may be an increased risk of certain arrhythmias at night, particularly in sleep disordered breathing, there is no evidence that supports different definitions for these arrhythmias during sleep compared with wakefulness. When the quality of tracings permits, the standard definitions of narrow- and wide-complex tachycardias and atrial fibrillation may be employed. In the future, expansion to multiple ECG leads and the use of alternative tools may provide better definition of heart rates and cardiac events during sleep.

[Early invasive strategy in acute coronary syndromes without persistent ST-segment elevation. Baseline characteristics and in-hospital outcome: Zabrze Registry]. / Obserwacja wewnatrzszpitalna i wyniki leczenia pacjentów z ostrymi zespolami wiencowymi bez przetrwalego uniesienia odcinka ST w osrodku dysponujacym mozliwosciami calodobowego leczenia inwazyjnego. Rejestr Zabrze.

Acute coronary syndromes (ACS) without ST elevation (which include unstable angina [UA] and non ST elevation MI [NSTEMI]) are caused by dynamic changes in the atherosclerotic plaque and coronary blood flow. To determine characteristics, in-hospital outcome and management of patients with ACS without ST elevation. The total of 502 patients were enrolled. Inclusion criteria were: rest angina within the last 24 hours, ST-segment deviation (>0,05 mV), T-wave inversion (>0,1 mV) in at least two leads, positive serum cardiac markers. There were 63,3% of patients with Braunwald's IIIB UA and 6,8% with IIIC UA, 29,9% of patients were diagnosed with NSTEMI. All patients were diagnosed invasively with subsequent revascularization (PCI-73,1% or CABG-16,7%) if apprioppriate. 1,6% of patients underwent PCI and elective CABG and 16,7% of patients were treated conservatively. Overall mortality was 2,98%--PCI subgroup (N = 367) 1,36%, CABG subgroup (N = 84) 8,33% and conservative subgroup (N = 43) 6,07%. Non-fatal myocardial infarction (MI) complicated the hospital course in 0,99%, 0,27%, 3,57%, and 2,32% of patients respectively. 1,4%, 0,54%, 6% and 0% of patients respectively had fatal MI. Early invasive strategy in patients with ACS without ST elevation is efficacious method of treatment.