Left bundle branch block (LBBB) is a conduction abnormality in the heart that can be seen on an electrocardiogram (ECG). In this condition, activation of the left ventricle of the heart is delayed, which causes the left ventricle to contract later than the right ventricle. Causes
Among the causes of LBBB are:
Aortic stenosis
Dilated cardiomyopathy
Acute myocardial infarction
Extensive coronary artery disease
Primary disease of the cardiac electrical conduction system
Long standing hypertension leading to aortic root dilatation and subsequent aortic regurgitation
Lyme disease

Mechanisms
Slow or absent conduction through the left bundle branch means that it takes longer than normal for the left ventricle to fully depolarise. This can be due to a damaged bundle branch that is completely unable to conduct, but may represent intact conduction that is slower than normal. LBBB may be fixed, present at all times, but may be intermittent for example occurring only during rapid heart rates. This may be due to the bundle having a longer refractory period than usual. Diagnosis
LBBB is diagnosed on a 12-lead ECG. In adults, it is seen as wide QRS complexes lasting ≥120ms with characteristic QRS shapes in the precordial leads, although narrower complexes are seen in children. In lead V1, the QRS complex is often entirely negative (QS morphology), although a small initial R wave may be seen (rS morphology). In the lateral leads (I, aVL, V5-V6) the QRS complexes are usually predominantly positive with a slow upstroke last >60ms to the R-wave peak. Notching may be seen in these leads but this is not universal.
A cerebrospinal fluid leak (CSF leak or CSFL) is a medical condition where the cerebrospinal fluid (CSF) surrounding the brain or spinal cord leaks out of one or more holes or tears in the dura mater. A cerebrospinal fluid leak can be either cranial or spinal, and these are two different disorders. A spinal CSF leak can be caused by one or more meningeal diverticula or CSF-venous fistulas not associated with an epidural leak.A CSF leak is either caused by trauma including that arising from medical interventions or spontaneously sometimes in those with predisposing conditions (known as a spontaneous cerebrospinal fluid leak or sCSF leak). Traumatic causes include a lumbar puncture noted by a post-dural-puncture headache, or a fall or other accident. Spontaneous CSF leaks are associated with heritable connective tissue disorders including Marfan syndrome and Ehlers–Danlos syndromes.A loss of CSF greater than its rate of production leads to a decreased volume inside the skull known as intracranial hypotension. Any CSF leak is most often characterized by orthostatic headaches, which worsen when standing, and improve when lying down. Other symptoms can include neck pain or stiffness, nausea, vomiting, dizziness, fatigue, and a metallic taste in the mouth. A CT myelography scan can identify the site of a cerebrospinal fluid leakage. Once identified, the leak can often be repaired by an epidural blood patch, an injection of the patients own blood at the site of the leak, a fibrin glue injection, or surgery.