Case Discussion <Brief History>      A 52-year-old man was admitted to our hospital because of increased frequency of syncope for 3 months.     He suffered from first attack of syncope about 10 years ago, which was noted by his family at home. No convulsion or myoclonus was noted and his consciousness recovered spontaneously about several minutes later. In the following years, he got syncope attacked once every year. He did not pay attention to it and did not take any medications. Unfortunately, the frequency of syncope attack increased up to twice per week since 3 months ago. He often experienced palpitation, air hunger, cold sweating and then awoke from sleep at midnight. He would go to bathroom for defecation and would have a sudden loss of consciousness if the duration of defecation was too long. His consciousness recovered in several minutes without confusion or memory loss. He visited another hospital, where 24 hours Holter-ECG revealed frequent VPCs. Amiodarone and beta-blocker were given, but the patient still had frequent syncope attacks and developed progressive exercise intolerance. So he visited the clinic and admitted for further evaluation.      He was a business man and denied smoking or alcohol drinking. Hypertension was told by the doctor in the local hospital 3 months ago, but he did not receive any medical treatment. He had no other systemic disease, operation or related family history. No orthopnea or paroxysmal nocturnal dyspnea was noted. Exercise intolerance developed after taking amiodarone and beta-blocker, but resolved if discontinued those drugs.      His consciousness was clear and oriented. The temperature was 36°C, the pulse was 64, the respiratory rate was 20 and the blood pressure was 130/80 mmHg. The conjunctivae were pink and the sclerae were anicteric. The neck was supple without jugular vein engorgement. The chest wall was symmetrical expansion with clear breath sound. The point of maximal impulse was localized at fifth intercostal space and left middle clavicular line. No thrill or heave was noted by palpation. The auscultation disclosed a grade II/VI pansystolic murmur over apex area without radiation. No S3, S4 gallop was noted. The abdomen was soft and flat, neither tenderness nor rebounding pain was complained. The liver and spleen were impalpable with a liver span of 8 cm along the right middle clavicular line. The bowel sound was normoactive. The extremities were freely movable without pitting edema or cyanosis. The other physical examinations were unremarkable. <Laboratory data> 1. CBC   WBC RBC Hb  HCT MCV MCHC PLT Date K/μL M/μL g/dl % fL g/dL K/μL 890314 5.56 6.03 13.2 41.1 68.2 32.1 198 2. BCS+Electrolyte   Alb Glo T-Bil D-Bil AST ALT ALP GGT  LDH Date g/dl g/dl mg/dl mg/dl U/l U/l U/l U/l U/l 890314 4.4 4.1 0.5 0.2 32 41 148 47 229   BUN CRE UA Na K Cl Ca P Mg Date mg/dl  mg/dl mg/dl mmol/l mmol/l  mmol/l mmol/l mg/dl mmol/l 890314 13.2 1.0 5.1 138 4.4 103 2.61 3.8 0.89   TG  T-CHO LDL  HDL Date  mg/dl mg/dl mg/dl mg/dl 890314 35 135 84 44   3. Coagulation    PT PTT Date Sec sec  890314 14.5/12.2 54.7/37.6  4. Urine    Outlook PH Sp Gr Pro Bil Sugar OB Uro K.B. WBC RBC Epith Date       mg/dl   g/dl   EU/dl         890314 Y;C 5.5 1.018 - - - - 0.1 - 0-1 - -  5. Stool Date Outlook Occult blood Pus cell 890314 YB;F - -   <CXR>       No cardiomegaly, clear lung field <ECG>(Figure 1)      NSR      Left anterior fascicular hemiblock     <Echocardiography & color duplex>          AO  37mm IVS 11 mm LVET    LVEF M-mode 70% AV 21 mm LVPW 10 mm M-EPSS        LA 35 mm LVEDD 50 mm   LV mass 228gm RV   LVESD 30 mm EF slope 59 cm/S     Ao flow(peak): 159 cm/S (PG:10mmHg) MV flow-E: 91cm/S, A-62cm/S TR flow(peak): 213cm/S (PG:18mmHg) PA flow-peak V: 109cm/S, Acc. T:165mS Mild AR,TR,PR Normal LA & LV size Good LV contractility   <Exercise ECG>89/3/16 Am 9:00    Indeterminate      Reason for terminate: dyspnea      Exercise duration: 9min      Maximal heart rate: 131 bpm (78% of predicted) <Holter ECG> Basically sinus rhythm Rare VPCs and SVEs Mild chest pain without significant ST depression <Ventricular late potential>       Total QRS duration: 119ms (<120ms)      Duration of HFLA signal: 36ms (<37ms)      RMS voltage: 20uV (>25uV)       →Negative <Carotid duplex>      Mild atherosclerosis over right bulb <EEG>      Normal chloral hydrate induced sleep EEG with basal lead study <Brain MRI>      No structural lesions <Electrophysiology Study> SA nodal function      No SNRT prolongation AV nodal function      AVW at S1S1 520ms      VAW at S1S1 650ms Carotid sinus massage      Ventricular pause> 2000msec during both carotid massage      Longest pause: 2999msec Ventricular extra-stimulation test      VEST performed at RVOT & RV apex      Single double triple extra-stimulation      Baseline & Isuprel 3 mg/min infusion            → Only 2 ventricular echo beats inducible                No sustained or non-sustained VT/VF inducible Procaimamide test      HV time: 28msec→ 51 msec      RBBB developed      ST-T change seemed secondary to RBBB Occasional multiform VPCs, during Isuprel infusion     Post-EPS diagnosis Hypersensitive carotid sinus Normal SA nodal function VPCs occasional, multiform No inducible VT/VF <Carotid sinus massage>     Protocol: Carotid massage for 5 minutes with BP, ECG monitor     Baseline: BP: 130/70, HR=60/min           HR drop to <40/min, BP drop to 70/42 mmHg           Longest RR interval= 3540 ms           Dizziness during carotid sinus massage <Head-up tilt table test>( Figure  2)     Protocol : Stage I :Upright 70o for 30 minutes                      Stage II:IV Isopreterenol 4 μg/min to increase HR 25%                     Endpoint: Syncope, Pre-syncope <Clinical course and treatment>       During hospitalization, 24-hr Holter ECG was negative. Echocardiography revealed a normal heart structure and normal flow of blood through the heart chambers and heart valves. LV contractility was good with an LVEF of 70%. Exercise ECG was stopped prematurely because of dyspnea. Ventricular late potential ECG was negative. MRI & EEG, which were arranged to evaluate neurological disease,were both negative. Carotid duplex disclosed only mild arteriosclerosis. EPS was performed and hypersensitive carotid sinus was suspected. Carotid sinus massage was repeated and showed a longest RR interval of 3540 ms, without associated symptoms. A head-up tilting table test, which has been reported to be a promising provovative procedure in evaluatingcardiovascular stability, was arranged and could induce a near-syncope in this patient. Vasovagal syncope was impressed and because of drug intolerance, DDDR pacemaker with rate drop response mode was implanted. He was discharged and was followed up at our OPD for 4 months without any more attacks of syncope. <Discussion>      Syncope is a sudden transient loss of consciousness and postural tone with spontaneous recovery. Loss of consciousness results from a reduction of blood flow to the reticular activating system located in the brain stem and does not require electrical or chemical therapy for reversal. Consequently, cessation of cerebral blood flow leads to loss of consciousness within approximately 10 seconds. Syncope is an important clinical problem because it is common, is costly, is often disabling, may cause injury, and may be the only warning sign before sudden cardiac death. Elderly persons have a 6 percent annual incidence of syncope. The cause of syncope remains unknown in about 50 percent of patients even after a careful history, physical examination, and 12-lead ECG are performed. Cardiovascular causes are associated with a 1-year mortality of 19 to 30 percent as compared to a 1-year mortality of about 6 percent in those patients with an unknown cause of syncope. The 1-year mortality in patients with syncope due to noncardiovascular causes is 1 to 12 percent. Sinus node dysfunction, tachyarrhythmias, and AV block are the three most common arrhythmic causes of syncope.      Two types of carotid sinus hypersensitivity have been described: cardioinhibitory and vasodepressor. The mechanism responsible for carotid sinus hypersensitivity is not known; possibilities include abnormalities of acetylcholine release or responsiveness, inadequate cholinesterase activity, high levels of resting vagal tone, or baroreflex hypersensitivity. In the cardioinhibitory type, a period of ventricular asystole exceeding 3 seconds is produced by carotid sinus stimulation. The vasodepressor type is defined as a decrease in systolic blood pressure of 50 mm Hg or more without slowing of the heart rate, or a decrease in systolic blood pressure of 30 mm Hg or more with reproduction of the patient's symptoms. Acutely, cardioinhibitory carotid sinus hypersensitivity can be prevented by atropine. Long-term therapy generally requires placement of a permanent pacemaker. Because of the associated AV-block in these patients, ventricular pacing (with or without atrial pacing) is usually required.      Orthostatic hypotension is most common in tall, asthenic individuals with poorly developed musculature. Some patients may prevent orthostatic hypotension by rising slowly from a recumbent position. Venous pooling occurs in many situations, some of which are dehydration, prolonged be rest, and blood loss. Patients with the idiopathic form of orthostatic hypotension also have a relatively fixed heart rate, anhidrosis, nocturnal polyuria, urinary and anal sphincter dysfunction, and impotency. Cardiac abnormalities, especially tachyarrhythmias and bradyarrhythmias, represent the second most common causes of syncope, accounting for 10 to 20 percent of episodes. Ventricular tachycardia is the rhythm disorder that most frequently causes loss of consciousness. Bradyarrhythmias such as sick sinus syndrome and advanced AV blocks can also result in syncope, but less commonly. 繼續教育考題 1. (D) All of the following statements regarding syncope are true except: A The cause of syncope is not identified in up to 50 percent of patients B One-year mortality in patients with syncope due to noncardiovascular causes in less than 15% C One-year mortality in patients with syncope due to cardiovascular causes is 19 to 30% D The diagnostic yield of an electrophysiological study in patients with unexplained syncope and structurally normal hearts is about 70% 2. (D) All of the following statements regarding syncope are true except: A Ten to 20 % of syncopal episodes are of cardiac origin B Syncope of cardiac origin is associated with a 30% 1 year mortality C The most common causes of syncope are vascular in origin, including reflex-mediated syncope and orthostatic hypotension D Supraventricular tachycardia is the most common tachyarrhythmia that leads to syncope 3. (D) All of the following statements regarding the hypersensitive carotid sinus syndrome are true except: A Atropine abolishes the cardioinhibitory form of this syndrome B During carotid sinus stimulation, a decrease in systolic blood pressure>30mmHg and reproduction of the patient's symptoms in consistent with the vasodepressor form of this syndrome. C The hypersensitive carotid sinus reflex is commonly associated with coronary artery disease D Single-chamber atrial pacing is sufficient therapy for most patients with carotid sinus hypersensitivity 4. (A) Which of following statement about the definition of orthostatic hypotension is true? A 20mm Hg drop in systolic or a 10 mm Hg drop in diastolic blood pressure within 3 minutes of standing B 30mm Hg drop in systolic or a 10 mm Hg drop in diastolic blood pressure within 3 minutes of standing C 20mm Hg drop in systolic or a 5 mm Hg drop in diastolic blood pressure within 3 minutes of standing D 20mm Hg drop in systolic or a 10 mm Hg drop in diastolic blood pressure within 5 minutes of standing 5. (C) A 30-year-old female in her third trimester of pregnancy has witness syncopal episode while lying supine on a couch. Physical examination reveals a systolic flow murmur and third heart sound. What is the most likely diagnosis? A Peripartum cardiomyopathy B Postprandial syncope C Neurocardiogenic syncope D Hyperventilation syndrome 6. (D) Which of following situations may bring on a neurocardiogenic syncopal episode? A Increased sodium intake B Exertion in a cool environment C Prolonged time in a supine position D A stressful or emotional situation 7. (B) Which of the following statements regarding orthostatic hypotension is true? A It is most common in short, overweight individuals B Slowly rising from a recumbent position may prevent orthostatic hypotension in some individuals C A large decrease in heart rate is associated with the idiopathic form of orthostatic hypotension D Orthostatic hypotension lasts for several seconds and then returns to normal 8. (D) A 20-year-old female presents with syncope following exertion. Physical examination reveals no murmurs. What is the most likely diagnosis? A Aortic stenosis B Cardiac tamponade C Hypertrophic cardiomyopathy D Primary pulmonary hypertension 9. (C) Which of following arrhythmias is the most frequently causes of loss of consciousness in patients diagnosed syncope? A Sinus bradycardia B Complete atrioventricular block C Ventricular tachycardia D Sick sinus syndrome 10. (A) What is the definition of duration of ventricular asystole exceeding produced by the carotid sinus stimulation in the cardioinhibitory type of carotid sinus hypersensitivity? A 3 seconds B 5 seconds C 10 seconds D 20 seconds 答案解說  The cause of syncope remains unknown in about 50 percent of patients even after a careful history, physical examination, and 12-lead ECG are performed. Cardiovascular causes are associated with a 1-year mortality of 19 to 30 percent as compared to a 1-year mortality of about 6 percent in those patients with an unknown cause of syncope. The 1-year mortality in patients with syncope due to noncardiovascular causes is 1 to 12 percent. Sinus node dysfunction, tachyarrhythmias, and AV block are the three most common arrhythmic causes of syncope. The diagnostic yield of EPS in a patient with an unknown cause of syncope and a structurally normal heart is about 12 percent, compared to a diagnostic yield of ~70 percent in patients with structurally abnormal hearts. Syncope may result from vascular, cardiac, neurological, and metabolic etiologies. Vascular causes of syncope are by far the most common, accounting for about one-third of all episodes. Vascular causes include orthostatic hypotension and reflex-mediated syncope, such as carotid sinus hypersensitivity and neurocardiogenic (vasovagal) syncope. It results from a defect in the normal blood pressure control mechanisms that are called into action when venous return to the heart is decreased upon standing upright (e.g., abnormalities of the reflex increase in heart rate, contractility, and systemic vascular resistance). Supraventricular tachycardias are much more likely to present with less severe symptoms, such as palpitations or lightheadedness rather than loss of consciousness. Two types of carotid sinus hypersensitivity have been described: cardioinhibitory and vasodepressor. The mechanism responsible for carotid sinus hypersensitivity is not known; possibilities include abnormalities of acetylcholine release or responsiveness, inadequate cholinesterase activity, high levels of resting vagal tone, or baroreflex hypersensitivity. There is a common association with coronary artery disease. Acutely, cardioinhibitory carotid sinus hypersensitivity can be prevented by atropine. Long-term therapy generally requires placement of a permanent pacemaker. Because of the associated AV-block in these patients, ventricular pacing (with or without atrial pacing) is usually required. Atropine and electronic pacing are not sufficient to prevent the fall in the blood pressure in patients with the vasodepressor type of carotid sinus hypersensitivity, which may result from inhibition of sympathetic vasoconstrictor activity. In such individuals, sodium-retaining drugs, elastic support hose, and avoidance of intravascular volume depletion may be beneficial. Drugs that enhance the response to carotid sinus massage, such as digitalis, clonidine, and beta-blockers, should be avoided. Orthostatic hypotension is defined as a 20 mm Hg drop in systolic or a 10 mm Hg drop in diastolic blood pressure within 3 minutes of standing. Neurocardiogenic syncope of an unusual type may be seen in pregnancy. The syncope may, in part, may be related to inferior vena caval compression by the gravid uterus when the patient is supine and is usually relieved by moving to the lateral decubitus position. Peripartum cardiomyopathy is a very uncommon disorder of unknown etiology. It would most likely present with symptoms of heart failure, although syncope from ventricular arrhythmias is possible. The physical examination findings are related to the normal physiology of pregnancy. Syncope from cardiac arrhythmias in patients with mitral valve prolapse is rare. Exertion in a warm environment, prolonged upright posture, sodium restriction, and stressful situations are important triggers for a neurocardiogenic syncopal episode. In pregnancy, the postural relationships are reversed, in that syncope in more likely to occur in the supine position than with upright posture. Orthostatic hypotension is most common in tall, asthenic individuals with poorly developed musculature. Some patients may prevent orthostatic hypotension by rising slowly from a recumbent position. Venous pooling occurs in many situations, some of which are dehydration, prolonged be rest, and blood loss. Patients with the idiopathic form of orthostatic hypotension also have a relatively fixed heart rate, anhidrosis, nocturnal polyuria, urinary and anal sphincter dysfunction, and impotency. The hypotension is progressive over a period of seconds to minutes, depending on the degree of loss of adaptation in that patients. There is usually a cardiac murmur to be notified in patients with aortic stenosis, mitral stenosis, and hypertrophy cardiomyopathy. The mostly presentation of cardiac tamponade is dyspnea, not syncope. The young female patient who presents with syncope during or shortly following exertion and has no cardiac murmur should be considered to have primary pulmonary hypertension until proven otherwise. While the prognosis of patients with noncardiac causes of syncope tends to be benign, those who have syncope of cardiac origin have a 30 percent mortality rate over the next year. Cardiac abnormalities, especially tachyarrhythmias and bradyarrhythmias, represent the second most common causes of syncope, accounting for 10 to 20 percent of episodes. Ventricular tachycardia is the rhythm disorder that most frequently causes loss of consciousness. Bradyarrhythmias such as sick sinus syndrome and advanced AV blocks can also result in syncope, but less commonly. In the cardioinhibitory type, a period of ventricular asystole exceeding 3 seconds is produced by carotid sinus stimulation. The vasodepressor type is defined as a decrease in systolic blood pressure of 50 mm Hg or more without slowing of the heart rate, or a decrease in systolic blood pressure of 30 mm Hg or more with reproduction of the patient's symptoms. Top of Page