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