Preterm babies born near 37 weeks often have no problems relating to prematurity if their lungs have developed adequate surfactant, which allows the lungs to remain expanded between breaths. Sequelae of prematurity can be reduced to a small extent by using drugs to accelerate maturation of the fetus, and to a greater extent by preventing preterm birth. Prevention
Historically efforts have been primarily aimed to improve survival and health of preterm infants (tertiary intervention). Such efforts, however, have not reduced the incidence of preterm birth. Increasingly primary interventions that are directed at all women, and secondary intervention that reduce existing risks are looked upon as measures that need to be developed and implemented to prevent the health problems of premature infants and children. Smoking bans are effective in decreasing preterm births. Different strategies are used in the administration of prenatal care, and future studies need to determine if the focus can be on screening for high-risk women, or widened support for low-risk women, or to what degree these approaches can be merged. Before pregnancy
Adoption of specific professional policies can immediately reduce risk of preterm birth as the experience in assisted reproduction has shown when the number of embryos during embryo transfer was limited. Many countries have established specific programs to protect pregnant women from hazardous or night-shift work and to provide them with time for prenatal visits and paid pregnancy-leave.
The small Q-waves that are usually seen in the lateral leads are absent in LBBB. T-waves usually point in the opposite direction to the terminal portion of the preceding QRS - positive QRS complexes have negative T-waves while negative QRS complexes have positive T-waves. The ST segments typically slur into the T-wave and often appear elevated in leads with negative QRS complexes. The axis may be normal but may be deviated to the left or right.There are also partial blocks of the left bundle branch: "left anterior fascicular block" (LAFB) and a "left posterior fascicular block" (LPFB). This refers to the block after the bifurcation of the left bundle branch. Diagnostic consequences
The presence of LBBB results in that electrocardiography (ECG) cannot be used to diagnose left ventricular hypertrophy or Q wave infarction, because LBBB in itself results in widened QRS complex, and changes in the ST segment consistent with ischemia or injury. Treatment
Patients with LBBB require complete cardiac evaluation, and those with LBBB and syncope or near-syncope may require a pacemaker. Some patients with LBBB, a markedly prolonged QRS (usually > 150 ms), and systolic heart failure may benefit from a biventricular pacemaker, which allows for better synchrony of heart contractions. See also
Bundle branch block
Right bundle branch block
Sgarbossas criteria

References


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