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Topic: Sinus node

Related Topics

Atrioventricular node

Heart rate

Bradycardia

Sick sinus syndrome

Vagus nerve

Autoimmune

Idiopathic

Premature ventricular contraction

	Re: Tachycardia
		The diagnosis of inappropriate sinus tachycardia is one of exclusion.
		The region of the sinus node was identified as the region of earliest atrial activation in sinus rhythm during electrophysiological study.
		Sinus node modification was successfully achieved in all 12 patients in whom it was attempted and was characterized by a 25% reduction in the sinus heart rate.
	www.medhelp.org /forums/cardio/archive/5916.html (1821 words)

	Sick Sinus Syndrome (Site not responding. Last check: 2007-10-26)
		Sick sinus syndrome (SSS) is a type of bradycardia in which the sinoatrial (SA), or sinus node is not working as it should.
		From the AV node, the signal is conducted along pathways that spread into the ventricles, causing them to contract and pump blood into the lungs and throughout the body.
		Sinus "pauses," or gaps between signals from the SA node, that indicate the heart is not being paced at the normal, steady rate.
	www.naspe-patients.org /patients/heart_disorders/sick_sinus (876 words)

	Sinus node definition - Medical Dictionary definitions of popular medical terms (Site not responding. Last check: 2007-10-26)
		The sinus node consists of a cluster of cells that are situated in the upper part of the wall of the right atrium (the right upper chamber of the heart).
		The electrical signal generated by the sinus node moves from cell to cell down through the heart until it reaches the atrioventricular node (AV node), a cluster of cells situated in the center of the heart between the atria and ventricles.
		The AV node serves as a gate that slows the electrical current before the signal is permitted to pass down through to the ventricles.
	www.medterms.com /script/main/art.asp?articlekey=8448 (458 words)

	Conduction system
		The artery to the sinus node is a branch of the initial course of the right coronary artery in just over half of all cases and of the start of the left circumflex coronary artery in the majority of the remaining cases.
		This landmark is delineated by the tendon of Todaro, the septal attachment of the tricuspid valve, and the mouth of the coronary sinus.
		The atrioventricular node and bundle of His are located within the triangle of Koch, which is formed by 1) the origin of the septal leaf of the tricuspid valve, the Thebesian valve, and the Eustachian valve of the vena cava and its anterior extension, known as the tendon of Todaro.
	www.pediheart.org /practitioners/anatomy/conduction.htm (1125 words)

	Arrythmia
		A sinus tachycardia is usually an appropriate response to a precipitating factor (e.g., exercise, fever, hypotension), although on occasion it may be inappropriate, as in the presence of a sympathetic dysautonomia (inappropriate sinus tachycardia).
		Sinus bradycardia may be due to an intrinsic abnormality of pacemaker cells, a parasympathetic dysautonomia (inappropriate sinus bradycardia), or an extrinsic factor such as suppression of automaticity by drug therapy (e.g., a beta blocker, a Ca2~ channel blocker, or an antiarrhythmic agent).
		Marked beat-to-beat variations in cycle length of the sinus rhythm, which are due virtually always to the influence of vagal tone on the pacemaker cells of the sinus node, also is considered an arrhythmia (sinus arrhythmia) even if the overall sinus rate is normal.
	www.rjmatthewsmd.com /Definitions/arrythmia.htm (714 words)

	Sinoatrial node -- Facts, Info, and Encyclopedia article (Site not responding. Last check: 2007-10-26)
		The sinoatrial node (abbreviated SA node, also called the sinus node) is the impulse generating (pacemaker) tissue located in the right atrium of the (The hollow muscular organ located behind the sternum and between the lungs; its rhythmic contractions pump blood through the body) heart.
		The sinoatrial node (SA node) is a group of cells positioned on the wall of the right atrium, near the entrance of the superior vena cava.
		Because the sinoatrial node is responsible for the rest of the heart's electrical activity, it is sometimes called the primary pacemaker.
	www.absoluteastronomy.com /encyclopedia/S/Si/Sinoatrial_node.htm (357 words)

	BestDoctors.com: Condition Summary: Bradycardia (Site not responding. Last check: 2007-10-26)
		The AV node, with the attached bundle of His, is the only route for electrical communication between the atria (containing the sinus node) and the ventricles.
		Intrinsic sinus node disease is increasingly common with advancing age and appears to be a manifestation of degenerative processes within the sinus node itself.
		The AV node and the conduction system which connect it electrically to the ventricles (the His bundle and bundle branches and the His-Purkinje system) are the only electrical pathway for transmission of the impulse generated by the sinus node to the ventricles.
	www.bestdoctors.com /en/conditions/b/bradycardia/bradycardia_120600.htm (2541 words)

	American Family Physician: Diagnosis and treatment of sick sinus syndrome
		Sick sinus syndrome is a generalized abnormality of cardiac impulse formation that may be caused by an intrinsic disease of the sinus node that makes it unable to perform its pacemaking function, or by extrinsic causes.
		It is unclear whether inflammation, sinus node ischemia, or local autonomic neural effects lead to the development of sick sinus syndrome in patients with myocardial infarction.
		The diagnosis of sick sinus syndrome may be difficult because of the slow and erratic course of the syndrome.
	www.findarticles.com /p/articles/mi_m3225/is_8_67/ai_100572096 (1336 words)

	Re: tachycardia
		Sinus tachycardia is defined as a heart rate of greater than 100 beats per minute originating from the sinus node.
		It is not clear what causes inappropriate sinus tachycardia but possible etiologies are an increase in the rate at which the sinus node depolarizes and an increased sensitivity to adrenaline.
		Inappropriate sinus tachycardia is an ill-defined clinical syndrome characterized by an increased resting heart rate accompanied by an exaggerated response to exercise or stress.
	www.medhelp.org /forums/cardio/archive/8049.html (1598 words)

	Nursing: Identifying inappropriate sinus tachycardia
		Inappropriate sinus tachycardia is characterized by an increased resting heart rate, or an increase in apparent sinus node rate disproportionate to the level of physical activity or emotional stress (100 beats/minute or more, or an increase to 100 beats/minute or more with minimal exertion).
		Sinus node function is within normal limits as evaluated by automaticity of the sinus node: The clinician uses overdrive pacing to suppress the sinus node, then records the recovery time following atrial pacing at high rates.
		The goal of modification is to salvage sinus node function while eliminating the high rates of sinus tachycardia that produce symptoms.
	www.findarticles.com /p/articles/mi_qa3689/is_200107/ai_n8979994 (1351 words)

	Children's Heart Institute \| How the Heart Works: The Heart Electric System
		The Sinus Node is considered to be the main switch of the heart which inititates the electric impulse of the heart and terminates it.
		The Sinus node is known as the pacemaker of the heart.
		The AV Node is responsible for transmitting the impulse from the atria to the ventricles.
	www.childrensheartinstitute.org /educate/heartwrk/elechhse.htm (1693 words)

	U-M CVC - Sick Sinus Syndrome (Site not responding. Last check: 2007-10-26)
		Sick sinus syndrome is rare in young people except when there is a history of heart surgery involving the heart’s upper chambers — the atria.
		The sinus node speeds up the heart rate when the body is active and slows it down when the body is at rest.
		In sick sinus syndrome, the sinus node is not able to adjust the heart rate to the level of activity.
	www.med.umich.edu /cvc/mchc/parsick.htm (498 words)

	Electrical System: Anatomy and Function - Children's Hospital Boston
		An electrical stimulus is generated by the sinus node (also called the sinoatrial node, or SA node), which is a small area of specialized tissue located in the right atrium (right upper chamber) of the heart.
		Under normal conditions, the sinus node generates an electrical stimulus every time the heart beats (60 to 190 times per minute, depending on the age of the child and his/her activity level).
		The electrical impulse then travels from the sinus node to the atrioventricular (AV) node, where it stops for a very short period, and continues down the conduction pathways via the bundle of His into the ventricles.
	www.childrenshospital.org /az/Site567/mainpageS567P0.html (341 words)

	MedlinePlus Medical Encyclopedia: Sick sinus syndrome
		Sick sinus syndrome usually occurs in people older than 50, where the cause is often a non-specific, scar-like degeneration of the heart's conduction system.
		In children, a common cause of sick sinus syndrome is heart surgery, especially to the atria (upper chambers).
		Holter monitoring is a sensitive tool to diagnose sick sinus syndrome because of the episodic nature of the disorder.
	www.nlm.nih.gov /medlineplus/ency/article/000161.htm (679 words)

	Sick sinus syndrome
		Sick sinus syndrome is a disorder of the sinus node of the heart, which regulates heartbeat.
		The sinus node in the heart functions as the heart's pacemaker, or beat regulator.
		A sick sinus node may be responsible for starting beats too slowly, pausing too long between initiation of heartbeats, or not producing heartbeats at all.
	www.healthatoz.com /healthatoz/Atoz/ency/sick_sinus_syndrome.jsp (830 words)

	eMedicine - Sinus Node Dysfunction : Article by Adrian W Messerli, MD
		Pathophysiology: SND is characterized by delayed or failed conduction between the sinus node and the atria, either due to inadequate sinus node pacemaking or because of intrinsic or extrinsic conduction disturbance.
		Autonomic dysfunction may be caused by vagal stimulation slowing the sinus rate and lengthening the refractory period of the sinus node.
		Inappropriate sinus bradycardia: Refractory sinus bradycardia, defined as bradycardia that does not increase with exertion, usually is the earliest manifestation of SND.
	www.emedicine.com /med/topic2132.htm (2732 words)

	New Page
		The heart is being paced by atrial tissue somewhere outside the sinus node.
		AV node premature beats may also be seen with an inverted P wave immediately in front of the QRS with an impossibly-short PR interval.
		After the PVC, the sinus beat is blocked, and the pause occurs as the ventricle “waits” for the next sinus beat.
	www.madsci.com /manu/ekg_rhy.htm (2011 words)

	Sinus dysrhythmia - MayoClinic.com (Site not responding. Last check: 2007-10-26)
		Sinus dysrhythmia refers to a malfunction of the sinus node, the heart's natural pacemaker.
		Located in the upper-right chamber (atrium) of your heart, the sinus node produces regular electrical impulses that spread to the lower chambers (ventricles) of the heart and initiate heart contractions.
		If the sinus node doesn't generate and send its impulses properly, your heart rate may speed up (tachycardia) and slow down (bradycardia) intermittently.
	www.mayoclinic.com /health/sinus-dysrhythmia/AN00787 (232 words)

	UpToDate Electrophysiologic evaluation of the sick sinus syndrome
		The abnormal responses in patients with sinus node dysfunction are listed in the accompanying table (show table 2).
		The atria are driven rapidly: a normal SA node will have a recovery time within certain limits, while recovery will be delayed in a depressed or sick sinus node.
		The SNRT may be corrected by subtracting the sinus cycle length from the SNRT (SNRTc) or by expressing it as a function of the cycle length, that is, SNRT/sinus cycle length.
	patients.uptodate.com /topic.asp?file=carrhyth/10795 (549 words)

	The clinical anatomy of the sinus node artery -- Berdajs et al. 76 (3): 732 -- The Annals of Thoracic Surgery (Site not responding. Last check: 2007-10-26)
		The clinical anatomy of the sinus node artery -- Berdajs et al.
		The clinical anatomy of the sinus node artery
		the sinus node artery and the superior posterior border of the
	ats.ctsnetjournals.org /cgi/content/abstract/76/3/732 (341 words)

	Ekg Abnormal Sinus Rhythm Results (Site not responding. Last check: 2007-10-26)
		a term used when the sinus node slows down or fails to initiate...
		Cardiac arrhythmia (dysrhythmia) is an abnormal heart rhythm resulting from any change, deviation or malfunction in the heart's conduction system -- the system through which normal electrical impulses travel through the heart.
		the heart's natural pacemaker (the sinus node) develops an abnormal rate or rhythm.
	www.ekg-machines.net /directory/ekg-abnormal-sinus-rhythm.html (504 words)

	THE MERCK MANUAL, Sec. 16, Ch. 205, Arrhythmias
		Sick sinus syndrome includes persistent sinus bradycardia, sinoatrial block manifested as sinoatrial Wenckebach, complete sinoatrial block, and sinus arrest (sinus impulse fails to activate the atria).
		Sick sinus syndrome is considered to be an intrinsic defect of the sinus node.
		However, many patients have features that suggest that abnormalities are not merely confined to the sinus node; coexisting atrioventricular nodal abnormalities are common.
	www.merck.com /mrkshared/mmanual/section16/chapter205/205o.jsp (257 words)

	eMedicine - Sinus Node Dysfunction : Article by M Silvana Horenstein, MD (Site not responding. Last check: 2007-10-26)
		Sinus pause or absence of an expected P wave for more than 3 seconds, which may be due to sinus arrest (failure of the SN pacemaker cells to depolarize) or due to sinoatrial exit block (depolarization of the SN but failure to conduct to the atria)
		The bradycardia may originate in the sinus, atria, atrioventricular junction, or ventricle, whereas the tachycardia is usually caused by atrial flutter or fibrillation and is less commonly caused by reentrant supraventricular tachycardia (SVT) in the SN or atrial muscle.
		The PR interval is 104 milliseconds, and the QRS is narrow at 86 milliseconds, with a normal axis of 64°.
	www.emedicine.com /ped/topic2533.htm (5305 words)

	Sick Sinus Syndrome: What You Should Know -- familydoctor.org (Site not responding. Last check: 2007-10-26)
		Sick sinus syndrome is the name for several conditions in which the sinus node does not work the right way.
		The sinus node is a natural pacemaker in your heart that helps your heart beat steadily.
		If you have sick sinus syndrome, your heart rate may be too slow or too fast to meet the needs of your body.
	familydoctor.org /767.xml (552 words)

	AllRefer Health - Sick Sinus Syndrome (Bradycardia-Tachycardia Syndrome)
		Sick sinus syndrome is a group of abnormal heartbeats (arrhythmias) presumably caused by a malfunction of the sinus node, the heart's "natural" pacemaker.
		Sick sinus syndrome is a relatively uncommon syndrome.
		Sick sinus syndrome may also be associated with tachycardias (fast heart rate) such as PSVT and atrial fibrillation.
	health.allrefer.com /health/sick-sinus-syndrome-info.html (443 words)

	Clinical Trial: Mode Selection Trial in Sinus Node Dysfunction (MOST)
		The underlying mechanisms by which dual chamber pacing is purported to improve outcome is straightforward; in patients with normal sinus rhythm, cardiac output is improved by 15 to 30 percent.
		Adverse effect of ventricular pacing on heart failure and atrial fibrillation among patients with normal baseline QRS duration in a clinical trial of pacemaker therapy for sinus node dysfunction.
		Association of prolonged QRS duration with death in a clinical trial of pacemaker therapy for sinus node dysfunction.
	clinicaltrials.gov /show/NCT00000561 (1073 words)

	Symptoms of Sinus node disease - WrongDiagnosis.com
		This signs and symptom information for Sinus node disease has been gathered from various sources, may not be fully accurate, and may not be the full list of Sinus node disease signs or Sinus node disease symptoms.
		Furthermore, signs and symptoms of Sinus node disease may vary on an individual basis for each patient.
		Note that Sinus node disease symptoms usually refers to various symptoms known to a patient, but the phrase Sinus node disease signs may refer to those signs only noticable by a doctor:
	www.wrongdiagnosis.com /s/sinus_node_disease/symptoms.htm (289 words)

	Sick Sinus Syndrome - Page 1 - HeartCenterOnline:
		Sick sinus syndrome (SSS) is a group of signs and symptoms that, when they occur together, are an indication that the
		The sinus node is a bundle of tissue, located in the upper right chamber of the heart (right
		The primary symptom of SSS is sinus bradycardia, a heart rhythm that is slower that 60 beats per minute.
	heart.healthcentersonline.com /arrhythmia/sicksinussyndrome.cfm (336 words)

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