Atrioventricular block types

Atrioventricular block type II, second or third degree Cardiac pacemaker... 

Verapamil, diltiazem Nonselective block of L-type calcium channels in vessels and heart Reduced vascular resistance, cardiac rate, and cardiac force results in decreased oxygen demand Prophylaxis of angina, hypertension, others Oral, IV, duration 4-8 h Toxicity Atrioventricular block, acute heart failure constipation, edema Interactions Additive with other cardiac depressants and hypotensive drugs... 

Paroxysmal atrial tachycardia with Wenckebach (Mobitz type I) atrioventricular block has been reported in a patient with a serum digoxin concentration of 3.2 ng/ml (39) and in a patient who in error took three times the recommended dose (40). 

Atrioventricular block. There are many types of AV block, such as a first-degree block in which atrial impulses are delayed in the AV conduction to the ventricle. This is shown on the ECG as a prolongation of the PR interval. Digitalis toxicity or excessive K+ levels can be causative. 

Several cases of American hellebore poisoning have been reported in persons who mistook the plant for ramps Allium tricoccum), a type of wild edible leek. Cases typically involved vomiting, slowed heart rate, and reduced blood pressure. Some cases include first- and second-degree atrioventricular block (Crummett et al. 1985 Jaffe et al. 1990 Prince and Stork 2000). 

Connelly DT, Steinhaus DM. Mobitz type I atrioventricular block an indication for permanent pacing PACE 1996 19 261-264. 

Shaw DB, Gowers JI, Kekwick CA, New KH, Whistance AW. Is Mobitz type I atrioventricular block benign in adults Heart 2004 90 169-174. 

Barold SS. Lingering misconceptions about type I second-degree atrioventricular block. Am J Cardiol 2001 88 1018-1020. 

Barold SS. Narrow QRS Mobitz type II second-degree atrioventricular block in acute myocardial infarction true or false Am J Cardiol 1991 67 1291-1294. 

Massie B, Scheinman MM, Peters R, Desai J, Hirschfield D, O Young J. Clinical and electrophysiologic findings in patients with paroxysmal slowing of the sinus rate and apparent Mobitz type B atrioventricular block. Circulation 1978 58 305-314. 

Cardiovascular Chronic aluminium exposure associated with cardiotoxic manifestations is rather rarely reported. A recent case study reported Mobitz type I second-degree atrioventricular block and nonsustained ventricular tachycardia (VT) following chronic occupational aluminium exposure [4 ]. 

An isolated nonconducted P wave (a P wave not followed by a QRS complex, as shown in the shaded areas below) may result from second-degree atrioventricular (AV) block type 11 or a nonconducted premature atrial contraction (RAQ. Thinking a patient has nonconducted PACs when he really has AV block can have serious consequences. The former is usually benign, but the latter can be life-threatening. 

Verapamil blocks both activated and inactivated L-type calcium channels. Thus, its effect is more marked in tissues that fire frequently, those that are less completely polarized at rest, and those in which activation depends exclusively on the calcium current, such as the sinoatrial and atrioventricular nodes. Atrioventricular nodal conduction time and effective refractory period are invariably prolonged by therapeutic concentrations. Verapamil usually slows the sinoatrial node by its direct action, but its hypotensive action may occasionally result in a small reflex increase of sinoatrial nodal rate. 

Calcium channel blockers inhibit L-type calcium channels in cardiac and smooth muscle. As a result, inhibition of calcium influx into cells occurs, causing a decrease in myocardial contractility and rate, resulting in reduced oxygen demand. Cardiac rate is slowed by the ability of calcium channel blockers to block electrical conduction through the atrioventricular (AV) node. In addition, calcium channel blockers can reduce systemic arterial pressure by relaxing arterial smooth muscle and decreasing systemic vascular resistance. 

ADVERSE EEEECTS AND PRECAUTIONS The /3 adrenergic blocking agents should be avoided in patients with asthma, with sinoatrial or atrioventricular (AV) nodal dysfunction, or in combination with other drugs that inhibit AV conduction, such as verapamil. Patients with type 1 diabetes mellitus also are better treated with other drugs e.g., ACE inhibitors). 

A dual chamber pacemaker (with one lead In the atrium and another in the ventricle) provides versatile programming functions and can sense and pace In both the atrium and ventricle. This type of pacemaker mimics the normal cardiac cycle and maintains atrioventricular (AV) synchrony. It may be used for patients with chronic or intermittent AV block and for those who need atrial pacing or have delayed AV conduction or an increased risk of heart block. 

Wolff-Parkinson-White (WPW) syndrome is a common type of preexcitation syndrome, an abnormal condition in which electrical impulses enter the ventricles from the atria using an accessory pathway that bypasses the atrioventricular (AV) junction. This results in a short PR intenral and a wide QRS complex with an initial slurring of the upward slope of the QRS complex, called a delta wave. Because the delta wave prolongs the QRS complex, it may be confused with a bundle-branch block. 

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