Christina Caron, Woman in Minnesota Helped Save Her Husband's Life, Then She Had a Baby. New York Times, Oct 26, 2018 https://www.nytimes.com/2018/10/ ... band-cpr-birth.html
("Ashley Goette of West St Paul, Minn * * * It all began last Tuesday [Ocr 23], around 5 am, when Ms Goette was awakened by her husband, Andrew. He seemed to be snoring. She nudged him and asked him to roll over. He didn't respond. Then she realized he wasn’t snoring at all: He was gasping for air. [Then the husband went into cardiac arrest.] * * * The hospital sedated Mr Goette and began lowering his body temperature in what would be a daylong procedure to induce mild [defined as below 35 degree C] hypothermia and reduce damage to the brain [procedure: induced or therapeutic hypothermia]. 'While they were doing that, it was the most terrifying thing to see,' Ms Goette said. 'His body was just convulsing [this is hyperbole; medical literature says 'quivering'].' The doctors administered a muscle relaxant to prevent involuntary movements. * * * Mr Goette later learned that he had Wolff-Parkinson-White syndrome, a rare condition also shared by his uncle [disease is not heritable] not that creates abnormal heart rhythms. It is even more rare for patients with this syndrome to go into cardiac arrest * * * The condition is caused by an extra electrical pathway between the heart’s upper and lower chambers that is present from birth. Mr Goette needed a procedure [radiofrequency catheter ablation: inserting a catheter into a heart chamber, whose tip generate heat to ablate the so-called Kent bundle] to destroy the tissue in his heart that was creating the improper pathways")
Note: There is no need to read the rest in any of the following references.
(a)
(i) WPW stands for cardiologists Louis Wolff (1898–1972; American), John Parkinson (1885–1976; English; not to be confused with namesake of Parkinson's disease, James Parkinson -- an English surgeon whose 1817 publication described the disease) and Paul Dudley White (1886–1973; American), due to their publication: Wolff L, Parkinson J and White PD, Bundle-Branch Block with Short P-R Interval in Healthy Young People Prone to Paroxysmal Tachycardia. American Heart Journal, 1930, 5: 685.
(b) WPW demonstrate a unique ECG.
(i) A heartbeat or contraction starts with depolarization of sinoatrial (SA) node, then of heart muscle cells constituting atrial wall to reach atrioventricular (AV) node. From the latter, the depolarization travel down special conductive pathway called Bundle of His. https://en.wikipedia.org/wiki/Bundle_of_His
(section 3 Etymology)
(ii) electrocardiography https://en.wikipedia.org/wiki/Electrocardiography
(section 5 Interpretation, section 5.1 Theory: read only the first two bullet points about depolarization (not repolarization in the next two) )
, or ECG for short, has P wave, QRS complex and T wave. Ignore T wave for the purpose of this posting. P wave represents (small) depolarization vector of atria (plural of atrium), whereas QRS complex (large) depolarization vector of ventricles (dominated by left ventricle, as it is much bigger than the right ventricle).
(A) PR interval (from the end of P wave to the start of Q) reflects the time interval that depolarization traverses atrial wall between SA node and Av node.
(B) For the purpose of understanding this NYT report, you need not know the electrophysiology underlying the components of QRS complex (Q-, R- and S-waves). In case you are curious, here it is:
ECG Interpretation Part I: definitions, criteria and characteristics of the normal ECG (EKG) Waves, Intervals, Durations & Rhythm. ECGwabes.com (non-profit; a "online nook and course"), undated. https://ecgwaves.com/ecg-normal- ... ent-t-wave-j-point/
(c)
(i) "When you have WPW, along with your normal conduction pathway, you have an extra pathway called an accessory pathway. They are normal heart muscle [but in the wrong place; given a misnomer Bundle of Kent or Kent bundle, as if being specialized electric tissue], not specialized electric tissue, and they ma * * * [c]onduct impulses in both directions
The impulses travel through the extra pathway (short cut) as well as the normal AV-HIS Purkinje system. The impulses can travel around the heart very quickly, in a circular pattern, causing the heart to beat unusually fast. This is called re-entry tachycardia or SVT (supraventricular tachycardia). Re-entry arrhythmias occur in about 50 percent of people with WPW; some patients may also have atrial fibrillation (a common irregular heart rhythm distinguished by disorganized, rapid, and irregular heart rhythm). Although rare, the greatest concern for people with WPW is the possibility of having atrial fibrillation with a fast ventricular response that worsens to ventricular fibrillation, a life-threatening arrhythmia."
Wolff-Parkinson-White Syndrome (WPW). Cleveland Clinic, reviewed in May 2017. https://my.clevelandclinic.org/h ... -white-syndrome-wpw
The hallmark is muscle in heart chambers (either atria or ventricular -- hence the name atrial or ventricular fibrillation) twitching but NOT contracting (so no blood is pumped).
(ii) Accessory pathway, Bundle of Kent and Wolff-Parkinson-White Syndrome. Cardiocases, undated http://www.cardiocases.com/en/ec ... ndle-kent-and-wolff
Quote:
"Patient[:] Young man 21 years of age applying for a professional firefighter's position, referred for identification of an abnormal [ECG] tracing; presented some episodes of tachycardia with sudden onset and end;
"A bundle of Kent is a muscle structure that pierces the atrioventricular fibrous skeleton and provides a direct accessory connection between the atria and the ventricles. In the majority of cases, the heart is devoid of other lesions * * * Its incidence decreases after the age of 50, mainly in conjunction with the involution of the accessory bundle.
"The diagnosis is initially electrocardiographic with evidencing of:
- a P wave most often normal * * *
- a short PR interval less than 120 ms [millisecond] * * *
- a delta wave; the delta wave denomination is derived from the triangular pattern of the beginning of the QRS complex; the premature ventricular activation begins at the ventricular insertion of the accessory pathway * * *"
Do view the two graphic at the bottom of the Web page, including the clicking of the ECG to see the delta wave. The "short PR interval" comes from "premature ventricular activation." third quotation 3.
(iii) "The surgical technique used in the first successful division of the bundle of Kent for treatment of the tachyarrhythmias associated with Wolff-Parkinson-White syndrome was reported in this journal in 1969 [by Seally himself]. The success of this and subsequent operations furnished the final proof that the bundle of Kent, an anomalous pathway between the atrium and ventricle, is the cause of this disorder. * * * The Kent bundles are microscopic in size and may occur in various locations around the right and left annulus fibrosus." (citations omitted).
Seally WC et al, The Surgical Treatment of Wolff-Parkinson-White Syndrome: Evolution of Improved Methods for Identification and Interruption of the Kent Bundle. Annals of Thoracic Surgery, 22: 443, 443 (1976) https://www.annalsthoracicsurgery.org/article/S0003-4975(10)64453-0/pdf
(iv) For histology 组织学 of the so-called Kent bundle, see
Dolinak D et al, Forensic Pathology; Principles and practice. Elsevier, 2005, at pages 03-94 and Image 4.73 https://books.google.com/books?i ... cardium&f=false
("A 46-year-old female, with a history of hypertension and ECG evidence of Wolff-Parkinson-White Syndrome (WPW), was found dead in her bedroom. Previous ECGs suggested that an accessory pathway was located somewhere around the right atrioventicular ring. The ring was serially sectioned, and a single thin accessory bundle of cardiac muscle (a so-called bundle of Kent) was found extending through the epicardial soft tissues between the right atrium and ventricle (Image 4.73). This provided anatomic confirmation of clinical diagnosis")
(A) In Image 4.73, heart muscle is stained pink, while fibrous tissue in atrioventricular ring, not stained, is transparent (due to thin sectioning 切片).
(B) You see, normally the boundary between atria and ventricles is atrioventicular ring, which is made of fibrous and electrically inert.