Diversity of electrical systole cardiac (página 2)

METHODS

• Exhaustive valuation of all cardiac symptoms-signs. (anamnesis and physical exploration)
• The electrocardiographically measures of waves, intervals and segments have been done through: Manual technological with Rule in millimetres. Technical in pixels with Miotool ® and Cardiosliper ®.
• Bazett’s and Fridericia’s Formulae.
• Valuation of normal dates: PQ interval ≥ 0.12 s and ≤ 0.20 s; QRS complex ≥ 0.06 s and ≤ 0.12 s; Q-Tc interval ≥ 0.350 s and ≤ 0.450 s

RESULTS (Table I)

Brother with an electrocardiography pattern of short PQ (≤ 0.12 seconds) and short Q-Tc value (≤ 0,350 seconds), has 37 years. Brother with an electrocardiography pattern of short PQ (≤ 0.12 seconds) and long Q-Tc value (≥ 0,450 seconds), has 35 years. Brother with an electrocardiography pattern of long PQ (≥ 0.20 seconds) and long Q-Tc value (≥ 0,450 seconds), has 33 years.

TABLE I

Two brothers have a punctuation of 4.5 in relation with Schwartz (Q-Tc interval > 0.460 s (two points); syncope in relation with physical effort (two points) and direct familiar history of sudden cardiac death. (0.5 points). One brother has short PQ and Q-Tc intervals.

DISCUSION (INTERPRETING THE RESULTS)

Here, we present the outlines electrocardiographic three brothers with a clear diversity of alterations in the electrical system heart. It is well established that the myocardium is more unstable and more vulnerable when there are variations in the duration of electrical systole. These disturbances can cause serious arrhythmias and even sudden cardiac death.

The electrical systole cardiac comprises:

• PQ interval or depolarization atrial complete.
• QRS complex or ventricular depolarization complete.
• T wave or ventricular repolarization complete.

The duration of the electrical systole cardiac (PQ-QRS-end T wave) has been considering within normal limits if still subject in a range between 40-45% of the total cardiac cycle (RR interval. Any alteration of these entities is likely to increase the vulnerability of the myocardium and the resultant myocardial electrical instability and the subsequent production of symptoms in the field myocardial with sudden changes in heart rate (tachycardia-bradycardia) occurrence of events of syncope (in relation or not with physical or emotional effort) and even sudden cardiac death. The vast majority of authors regard as limit values of the QTc interval (Bazett) between 0.44 seconds (maximum value) and 0.35 seconds (minimum value). (1, 2, 3.). Both a prolonged QT interval and decreased PQ and QT interval have been proposed as surface EKG markers of vulnerability to ventricular arrhythmias and potential predictors of mortality. (4, 6, 7). If we add to this the presence of a Short PQ interval with a Short QT interval, the probabilities of occurrence of serious developments related, could grow up exponentially.

The QT interval, in its basic form, is a seemingly simple concept. Defined as the interval from the beginning of the QRS complex to the end of the T wave on a surface EKG, the QT interval represents the period of global ventricular depolarization and subsequent repolarization. Prolongation of the QT interval due to inherited ion channel abnormalities or due to drugs or metabolic abnormalities has been associated with an increased incidence of ventricular arrhythmias.

In addition, experimental studies have demonstrated that regional differences in repolarization facilitate re-entry and the development of ventricular arrhythmias. Heterogeneous ventricular repolarization was recognized from surface EKGs as early as 1934. Over a decade ago, the difference between the longest and shortest QT intervals on a standard 12-lead EKG (QT dispersion) was forwarded as a simply measured marker for vulnerability to ventricular arrhythmias and risk for sudden cardiac death. However, the exact physiologic mechanism and true clinical utility of QT dispersion has been the subject of intense debate over the past several years.

In general, interobserver and intraobserver variability of PQ and QTc intervals measurements can be as much as 30 to 40% (7). Recent studies suggest that using a specific combination of "quasiorthogonal" leads (aVF, V1, and V4; I, aVF, V2, and V4) may provide sufficient Q-Tc interval data for analysis. Other authors (including us) consider V4-V5-V6 as the derivations with better predictive value (they are "looking directly at the left ventricle"). (3, 4, 5.). However, at this time no standardized method for acquiring Q-Tc interval exists.

CONCLUSIONS

Clinicians would be vigilant in screening and monitoring for electrocardiographic measurements in patients with symptoms cardiac (7). All doctors would make a comprehensive assessment of the values of the different duration of electrocardiographic intervals, segments and waves for the purpose of avoiding underdiagnosis in patients with cardiac symptoms. On many occasions we can see that the signal is slight, anecdotal and without compromise vital, but in many others – such as the work exposed- the signal is serious, with high risk of sudden cardiac death according the scale of Schwarzt (the most commonly used in the present times for risk stratification). Two brothers have a punctuation of 4.5 in relation with Schwartz: Q-Tc interval > 0.460 s (two points); syncope in relation with physical effort (two points) and direct familiar history of sudden cardiac death. (0.5 points). In other words, High Risk of Sudden Cardiac Death. [Table I]

BIBLIOGRAPHY

1. Cowan JC, Yusoff K, Moore, M, et al. Importance of lead selection in QT interval measurement. Am J Cardiol .1988; 62, 83-87.
2. Zabel M, Franz MR, Klingenheben T, et al. Rate-dependence of QT dispersion and the QT interval: comparison of atrial pacing and exercise testing. J Am Coll Cardiol .2000; 36, 1654-1658.
3. Glancy JM, Garratt CJ, Woods KL, et al. Three-lead measurement of QTc dispersion. J Cardiovasc Electrophysiol .1995; 6,987-992.
4. Behrens S, Li C, Knollmann BC, et al. Dispersion of ventricular repolarization in the voltage domain. Pacing Clin Electrophysiol .1998; 21,100-107.
5. DeBruyne, MC, Hoes, AW, Kors JA, et al. QTc dispersion predicts cardiac mortality in the elderly: the Rotterdam Study. Circulation 1998; 97,467-472.
6. Gussak I, Brugada P, Brugada J, et al. Idiopathic short QT interval: a new clinical

Syndrome? Cardiology. 2000; 94: 99–102.

7. Recommendations for the Standardization and Interpretation of the Electrocardiogram Part I: The Electrocardiogram and Its Technology: A Scientific statement From the American Heart Association Electrocardiography and Arrhythmias Committee, Council on Clinical Cardiology; the American College of Cardiology Foundation; and the Heart Rhythm Society Endorsed by the International Society for Computerized Electrocardiology. Circulation. 2007; 115:1306-1324.

Figure 1.

Images with outline electrocardiographic of the three brothers.

Outline A: Brother of 33 Years; Outline B: Brother to 35 years. Outline C: Brother to 37 years.

Table II

Mixed images.

Figure 2.

Complete layouts electrocardiographic all three brothers

Autor:

Francisco Ramón Breijo Márquez