Wide Complex Tachyarrhythmias Research Articles

Neonatal Near Fatal Flecainide Toxicity

Background: Flecainide is an anti-arrhythmic medication with a narrow therapeutic index and a high mortality rate, when overdosed. Few cases of flecainide toxicity in neonates and children due to medication error have been reported in the literature. A case of an accidental flecainide overdose in a neonate in Oman was presented. Case Presentation: A 19-day-old newborn girl developed persistent supra ventricular tachycardia (SVT) after receiving nebulized albuterol for acute bronchitis. After unsuccessful treatment with adenosine, she was given flecainide 5.6 mg orally every 24 hours for resolution of the SVT. On day four of admission, the child inadvertently received 100 mg of flecainide orally due to a dose calculation error. The child developed wide complex tachyarrhythmia followed by pulseless ventricular tachycardia (VT) requiring cardiopulmonary resuscitation. Sodium bicarbonate IV bolus followed by an infusion was administered. The patient developed two additional episodes of pulseless VT that coincided temporally with two interruptions of the sodium bicarbonate infusion, and required high dose of inotropic support. The patient developed convulsions but her brain ultrasound was normal. Her condition stabilized on day three after the toxicity occurred. Repeated echo showed a normal EF. The patient was discharged on propranolol and levetiracetam and was doing well on outpatient follow up. Conclusion: Flecainide is a potentially lethal medication in overdose due to its sodium channel blocking properties. Sodium bicarbonate remains an essential component of treatment.

Understanding the modern-era management of cardiac tachyarrhythmias

Diagnosis and treatment modalities of supraventricular arrhythmias have been changed over the past decade. This article mainly outlines advances in diagnosis and modern-day management of supraventricular tachycardia as well as an overview of the management of wide complex tachyarrhythmias. The role of cardiac electrophysiology study and radiofrequency catheter ablation in the diagnosis and management of a wide variety of supraventricular arrhythmias is also discussed. This article also emphasizes the current evidence-based management of atrial-origin tachyarrhythmias such as atrial flutter and fibrillation.The management of cardiac arrhythmias has changed over the past decade, which is mainly due to improvements in catheter ablation including 3D mapping catheter ablation, improvements in device therapy such as implantable cardioverter defibrillator (ICD) and biventricular pacing therapy (CRT) which have evolved to treat many conditions. Catheter ablation has moved from being a treatment considered only for patients with refractory arrhythmias to a first-line treatment. In the new era, catheter ablation is also used to treat atrial origin tachyarrhythmias such as atrial fibrillation (AF) and atrial flutter as well as ventricular tachycardia (epicardial VT ablation). Improvement of imaging modalities such as 2D/3D echocardiogram and cardiac MRI also play a vital role in the prognosis of ablation particularly in AF and epicardial VT ablation. Improvement in device implantation such as ICD and biventricular pacing also helpful in managing tachyarrhythmia. Modern advancements in cardiac electrophysiology help patients to improve their quality of life and prevent sudden cardiac deaths due to cardiac arrhythmia.

678 WIDE COMPLEX TACHYCARDIA IN A PATIENT TREATED WITH PERMANENT HIS BUNDLE PACING: A CASE REPORT

Abstract Introduction Differential diagnosis of wide complex tachycardias based only on ECG analysis remains a challenging exercise. But, when intracardiac tracings are available (i.e., pacemaker EGM), electrophysiologists may consider several tricks to make a correct diagnosis. Case Presentation A 73-years-old sporty male was admitted to our hospital for palpitations and dizziness. ECG monitoring revealed AF, typical atrial flutter and asystolic pauses following spontaneous cardioversion of atrial arrhythmias. We diagnosed sick sinus syndrome and implanted a dual-chamber pacemaker with an atrial lead in the right appendage and a stylet-directed active fixation lead in the His region, obtaining non-selective narrow paced QRS. The day after PM implantation, during a new episode of AF, two runs of regular wide-complex tachycardia (LBBB morphology, cycle length of 270 ms) occurred (Fig 1A, B). LBBB morphology, patient's history, and AF favored aberrancy, but couldn't exclude VT or preexcitation (by atrio-fascicular AP). Our diagnostic strategy consisted in adding atrial and His intracardiac electrograms registered by pacemaker to analysis of ECG traces. The device interrogation showed AV dissociation at the time of the wide complex tachyarrhythmia and a negative HV interval (Fig. 2A). These findings ruled out aberrant ventricular conduction and bundle branch reentrant tachycardia, because both these arrhythmias are characterized by HV ≥ HV in sinus rhythm. We performed incremental atrial pacing maneuver, during SR, obtaining decremental AH conduction with constant HV interval (60 ms), excluding atrio-fascicular, nodo-fascicular and nodo-ventricular AP. His bundle activity was identified just after the ventricular activation, producing a relatively short VH interval, suggesting the presence of a retrograde activation of the His bundle, therefore it was possible to hypothesize that the site of origin of the ventricular arrhythmia was within/or very close to RBB (Fig 2B, C). Just in few beats His bundle deflection was missing, probably because of recovery of functional LBBB (Fig 2D). Discussion Our final diagnosis was RBB VT. Patient was treated with Verapamil 80 mg t.i.d., with no further recurrence. This case highlights the diagnostic value of device interrogation in patients with permanent His bundle pacing, for the evaluation of wide complex tachycardias.

Stereotactic Arrhythmia Radioablation (STAR)

Ventricular tachycardia(VT) is a wide complex tachyarrhythmia which could be potentially life-threatening. Standard treatment options include catheter ablation, anti-arrhythmic drugs and ICDs (Implantable cardioverter defibrillator). In patients refractory to the above treatments, limited options are available. Stereotactic arrhythmia radio-ablation (STAR) is a novel non-invasive method of ablating the arrhythmogenic substrate using high dose of highly focused radiotherapy. This technique requires a multi-disciplinary team consisting of Cardiologist, Electrophysiologist, Radiation oncologist and Radiologist to integrate pre-treatment imaging and electro-physiological data to generate a target that can be radiated. Studies show excellent control of VT, 6–12 weeks post-treatment with no major toxicities. This article attempts to provide a practical step by step approach to stereotactic arrhythmia radioablation.

THE FORGOTTEN TRUTH ABOUT COMMON COLD FORMULATIONS’ POTENTIAL TO CAUSE WIDE COMPLEX TACHYCARDIA AND SEIZURES

SESSION TITLE: Medical Student/Resident Cardiovascular Disease Posters SESSION TYPE: Med Student/Res Case Rep Postr PRESENTED ON: October 18-21, 2020 INTRODUCTION: First-generation antihistamines: diphenhydramine and doxylamine are readily available over the counter medications. These drugs are commonly used as sleep aids, cold, and allergy medications due to their anticholinergic and anti-histamine effects. Here we present a 19-year-old female, who presented to the hospital after an intentional overdose of over the counter cold medications. This case serves to remind us of the potential for life-threatening arrhythmias associated with these medications. CASE PRESENTATION: We present a 19-year-old-year-old female with a past medical history of depression, dissociative identity disorder, and multiple suicide attempts who called EMS after reporting an intentional overdose of unknown quantities of Nyquil, Unisom, and Benadryl. Daily Ativan was her only home medication. En route to the hospital, she had two witnessed tonic-clonic seizures, which resolved after two doses of Ativan. On admission, she was alert but irritable, easily startled, and confused. She had no cardiac or respiratory symptoms. Vital signs were stable except for heart rates in the 160s. Initial EKG showed a wide complex tachycardia, a left bundle branch block and left axis deviation. Troponins were negative. She was given a dose of physostigmine, several bicarbonate pushes, and eventually started on a sodium bicarbonate infusion. Due to worsening mental status and upper extremity myoclonic jerks concerning for ongoing seizures, she was intubated for airway protection. After 5 hours of sodium bicarbonate infusion, the wide complex tachycardia resolved. During her 10-day hospital stay, she developed hypokalemia and metabolic alkalosis, which resolved after potassium supplementation and cessation of bicarbonate infusion respectively. In addition, she developed rhabdomyolysis and lactic acidosis both of which resolved after fluid resuscitation. The patient continued to have intermittent myoclonic jerks and new vertical nystagmus. EEG did not show seizure activity. Her mental status returned to baseline. EKG remained in normal sinus rhythm and she was finally discharged with close psychiatry follow up. DISCUSSION: We present a patient who overdosed on first-generation anti-histamines resulting in a wide complex tachyarrhythmia and seizures. Cardiac arrhythmias develop due to increased excitability, slowed conduction of the fast inward sodium current as well as QT interval prolongation. Antagonism at the H1 receptor mediates seizure activity. Management should be focused on early pattern recognition, sodium bicarbonate, and anti-epileptic therapy. CONCLUSIONS: Although widely used and easily available, over the counter formulations are an increasingly rare but possible cause of life-threatening arrhythmias and seizures if taken in large amounts. It is imperative that patients be educated on the potential side effects of these commonly prescribed medications. Reference #1: Joshi, Ajay K., et al. “Case of Polymorphic Ventricular Tachycardia in Diphenhydramine Poisoning.” Journal of Cardiovascular Electrophysiology, vol. 15, no. 5, 2004, pp. 591–593., doi:10.1046/j.1540-8167.2004.03173.x Reference #2: Su, Mark, and Matthew Goldman . “Anticholinergic Poisoning.” UpToDate, 2019, www.uptodate.com/contents/tricyclic-antidepressant-poisoning?topicRef=305&source=see_link#H15. DISCLOSURES: No relevant relationships by Andre Gabriel, source=Web Response No relevant relationships by Jasmin Hundal, source=Web Response No relevant relationships by Brenda Nyatanga, source=Web Response

Robust Detection of Wide Complex Tachyarrhythmias Using Mobile Cardiac Telemetry Monitors

Introduction Wide Complex Tachyarrhythmias (WCT) are commonly observed arrhythmias in patients with heart failure. Automatic identification of WCT using mobile cardiac telemetry (MCT) monitors is critical for high-quality patient care due to their potentially lethal nature. There is very limited literature on validating an algorithm's ability in detecting WCTs in near real-time in the outpatient setting. This study demonstrates the efficacy of the ZywieAI® algorithm in detecting episodes of sustained and/or non-sustained WCTs like ventricular tachycardia, ventricular flutter, and ventricular fibrillation. Method We propose a three-pronged approach to identify WCT episodes in ECG recordings where the heart rate is ≥100 bpm for ≥3 consecutive beats. Firstly, the ECG frequency spectrum is analyzed to identify the time instants of QRS onset-offset and fiducial points in the signal. Secondly, four novel discrete features are extracted from the fiducial points and ectopic beats to get a beat-level assessment. Lastly, a rule-based decision classifier interprets input features to identify a true WCT episode. Results The ZywieAI® algorithm was evaluated by analyzing 299 WCT episodes in three public PhysioNet databases: MIT-BIH Arrhythmia (MITBA), MIT-BIH Malignant Ventricular Arrhythmia (MITMVA), and CU Ventricular Tachyarrhythmia (CUVT). These annotated databases contain ECG recordings with a wide variety of PQRST morphologies and arrhythmias contaminated with noise, which make the WCT detection a challenging problem. The proposed algorithm identified patients who experienced WCT with 100% accuracy in all three databases. At the individual episode-level, the algorithm had an average gross sensitivity (Se) and specificity (Sp) of 94.8% and 97.6% for MITBA and 94.1% and 89.1% for MITMVA databases, respectively. The episode-level Se for CUVT database was 100%. Furthermore, the Se of the algorithm in identifying any WCT episode with ≥ 10 beats was 100%, 99.8%, and 100% for the respective databases. Conclusion The results suggest that the ZywieAI® algorithm can robustly identify WCT episodes as short as 0.46 seconds. The proposed algorithm can be used to evaluate real-time ECG signals in remote cardiac monitoring studies, assisting clinicians in the timely diagnosis of patients with most lethal wide complex arrhythmias.

Fascicular Tachycardia: The Great Masquerader

SESSION TITLE: Cardiovascular Disease SESSION TYPE: Affiliate Case Report Poster PRESENTED ON: Tuesday, October 31, 2017 at 01:30 PM - 02:30 PM INTRODUCTION: Hemodynamically stable tachycardia in a young seemingly healthy individual is generally assumed to be supraventricular in origin. However there is a type of ventricular tachycardia (VT) that has a relatively narrow complex that presents in young healthy individuals and is frequently misdiagnosed as supraventricular ventricular tachycardia (SVT). We present such a case and demonstrate the consequence of delayed diagnosis. CASE PRESENTATION: Our case is a 39 year old male with no past medical history who presented to our emergency department with one day of palpitations and diaphoresis. He first noted these symptoms in adolescence, which were of shorter duration and therefore medical attention was never sought. On arrival to our institution the patient was hemodynamically stable on presentation with an unremarkable physical exam other than a pulse rate of 200 bpm with an EKG showing wide complex tachycardia (figure 1). In addition his blood chemistries were all within normal limits. Despite receiving multiple rounds of adenosine (6mg, 12mg, 12mg) followed by electrical cardioversion, patient remained in wide complex tachycardia. Patient was then given Diltiazem 20mg IVP, which resulted in conversion to normal sinus rhythm (figure 2). Closer investigation of the presenting ECG revealed a leftward (northwest) axis and an incomplete RBBB pattern with RSR’ complexes, a finding highly specific for ventricular tachycardia (VT). An Echocardiogram at our institution revealed no structural heart disease with normal ventricular systolic function. Patient was taken for further electrophysiological testing which confirmed Left Fascicular VT. Patient underwent radiofrequency catheter ablation without any complications. DISCUSSION: Fascicular tachycardia typically originates in the region of the left posterior fascicle and has a RBBB, left superior axis morphology and AV disassociation. In most, a resting EKG is normal and there is no evidence of structural heart disease evidenced by echocardiography and coronary angiography. The narrow QRS complex (typically 0.12 to 0.14 sec) morphology distinguishes fascicular VT from most VTs, but it also resembles SVT frequently leading to misdiagnosis. CONCLUSIONS: Our goal is to help clinicians, especially those who first encounter patients’ with this presentation, be cognizant about the subtle important features of fascicular tachycardia. When it comes to wide complex tachyarrhythmias’ clinicians often have a sense of uneasiness, further clouding their clinical judgment. It is therefore imperative to recognize cases of Idiopathic VT, precisely fascicular tachycardia so they can be differentiated from svt and treated appropriately. Reference #1: Brooks R, Burgess JH. Idiopathic ventricular tachycardia. A review. Medicine (Baltimore) 1988; 67:271. Reference #2: Belhassen B, Viskin S. Idiopathic ventricular tachycardia and fibrillation. J Cardiovasc Electrophysiol 1993; 4:356. DISCLOSURE: The following authors have nothing to disclose: Shahab Khan, Ravi Mann, Fawzi Ameer, David Slotwiner No Product/Research Disclosure Information

Wide complex tachycardia – diagnostic and therapeutic challenges

Dilated cardiomyopathy is associated with ventricular arrhythmias and with an increased risk of sudden cardiac death. In these cases, wide complex tachyarrhythmias are frequently a diagnostic challenge. The efficiency of antiarrhythmic drug therapy is limited and often the implantation of a cardiac defibrillator is required. We hereby present the case of a 68 year old male patient known with dilated cardiomyopathy, who experienced a syncopal episode as the clinical expression of a wide complex tachycardia. The recorded electrocardiogram identified ventricular tachycardia originated in the right ventricle or in the interventricular septum. The electrocardiograms recorded before and after the syncopal episode showed a major left bundle-branch block and a first degree atrioventricular block. 24-hour Holter ECG monitoring detected ventricular tachycardia originating in the left ventricle. The etiology of the dilated cardiomyopathy, arrhythmias and conduction abnormalities could not be identified. During the electrophysiological study, no sustained supraventricular or ventricular tachyarrhythmias were triggered. The pharmacological treatment has been optimized and a cardiac defibrillator was implanted. The particularity of this case consists in the presence of multiple rhythm disturbances originating both in the left and right ventricle, in a patient with idiopathic dilated cardiomyopathy and conduction disturbances at several levels.

P473Subsequent 12-lead electrocardiograms help differentiate wide-complex tachyarrhythmia events

P473Subsequent 12-lead electrocardiograms help differentiate wide-complex tachyarrhythmia events

This Is the Year to Listen to Yourself.

This Is the Year to Listen to Yourself.

Successful Cryoablation of Mahaim Tachycardia in a Child With Ebstein’s Anomaly

Mahaim fibers with decremental atrioventricular (AV) node-like conduction properties comprise less than 3 % of accessory pathways. Radiofrequency ablation of right atriofascicular pathways guided by a distinct Mahaim potential detected at the anterolateral to posterolateral tricuspid annulus or in the right ventricular free wall is a safe and highly effective treatment method. The case report presents a 16-year-old boy with Ebstein's anomaly and symptomatic wide complex tachyarrhythmia. The electrophysiologic study and the entire ablation procedure were performed using a three-dimensional mapping system (EnSite Velocity; St. Jude Medical Inc., St. Paul, MN, USA). No fluoroscopy was used during the procedure. Electrophysiologic evaluation demonstrated typical atrioventricular nodal reentrant tachycardia and Mahaim tachycardia with a wide QRS and a left bundle branch block pattern. After Mahaim potential was located at the lateral tricuspid annulus, successful cryoablation was performed with an 8-mm-tip catheter followed by slow pathway ablation to eliminate typical atrioventricular nodal reentrant tachycardia. Cryoablation with an 8-mm-tip catheter can be an alternative treatment option for children with Mahaim tachycardia.

Bidirectional fascicular tachycardia with alternating axis deviation following acute myocardial infarction

A 46-year-old male without past medical history presented to the emergency department complaining of severe chest pain. Blood pressure was 100/70 mm Hg, heart rate was 66 bpm, and the oxygen saturation was normal. The 12-lead ECG showed ST segment elevation in leads I, avL and throughout the precordial leads (Fig. 1A). Urgent coronary angiography was performed and demonstrated a complete thrombotic occlusion of the mid left anterior descending artery (LAD) as well as a more proximal 70% luminal narrowing of the LAD. Percutaneous transluminal coronary angioplasty and stent implantation of the mid LAD was successfully performed with restoration of grade TIMI 3 flow in the LAD. The patient was admitted to the cardiac intensive care unit after successful stent implantation. ECG performed 1 h after reperfusion (Fig. 1B) showed a wide complex tachyarrhythmia with right bundle branch block (RBBB) morphology and alternating axis deviation. This arrhythmia spontaneously resolved to normal sinus rhythm (Fig. 1C). The patient was discharged with medical therapy including a beta blocker and without any complications. The 12-lead ECG recording demonstrates a bidirectional tachycardia in which all the beats have features of RBBB and the QRS axis in the frontal plane alternates between right and left axis deviations (Fig. 1B). The width of the QRS complex is only 110 ms, thus corresponding to a tachycardia originating within the left bundle branch (LBB) or its fascicles. The illustration (Fig. 2) is based on the assumption that the focus of the tachycardia was situated in the left bundle just above the division into the left posterior fascicle (LPF) and the left anterior fascicle (LAF) with impulses conducting to the myocardium using the LAF and LPF alternately, hence the alternating axis. Even though His bundle potentials were not recorded during the bidirectional tachycardia, the relatively narrow width of the QRS and the alternating axis together with RBB leaves no doubt regarding the location of the automatic focus in the territory of the LBB. This concept was documented by His bundle recordings by Massumi back as 1973 [1] and by clinical observations since 1977 [2]. The QRS morphology and rate of arrhythmia corresponds to the majority of the cases of reperfusion arrhythmias also known as accelerated idioventricular rhythm (AIVR) [3]. However, the unique feature is the alternation of the QRS axis in the frontal plane suggesting functional block in the two fascicles. As is usually the case, the tachycardiawas self-limited and resolved spontaneously. The majority of the AIVR cases have rates under 120/min and do not cause hemodynamic deterioration. However, it is important to distinguish the reperfusion AIVR from the more dangerous type of bidirectional ventricular tachycardia (VT) seen in the course of digitalis intoxication [4] and severe myocardial damage such as myocarditis [5]. This patient had no history of digitalis use and the arrhythmia occurred during the reperfusion period making bidirectional VT very unlikely. Bidirectional VT has not been reported in the setting of acute myocardial infarction. It should also be noted that the early publication of cases of AIVR emphasized the point that the occurrence of AIVR usually indicated restoration of flow to the infarcted region [3]. In recent publications, it has been reported that AIVR also appears in several drug intoxications [3], post-resuscitation [6] and idiopathic dilated cardiomyopathy [7]. There is general agreement that the electrophysiological mechanism of AIVR is enhanced automaticity of the His bundle and/or its divisions. To the best of our knowledge, this is the first report of alternating LAF and LPF block in the setting of the RBBB and fascicular rhythm in a patient with acute anterior myocardial infarction. The authors of this manuscript have certified that they comply with the Principles of Ethical Publishing in the International Journal of Cardiology [8].

Electroanatomic localization of a slowly conducting atrioventricular (Mahaim) accessory pathway

We present a case of a 34-year-old female with Ebstein's anomaly and symptomatic wide complex tachyarrhythmia. Electrophysiologic evaluation demonstrated antidromic tachycardia utilizing a right-sided decremental, slowly conducting atrioventricular pathway. Distinct accessory pathway potentials along the length of the bypass tract were sequentially recorded to define the anatomic course of the pathway, as uniquely represented on a three-dimensional electroanatomic map, and to successfully guide catheter ablation.

The clinical utility of adenosine in difficult to diagnose tachyarrhythmias.

The use of intravenous adenosine to help differentiate the origin of tachyarrhythmias has been suggested to be beneficial. However, the benefit of this intervention to physicians with different levels of training in electrocardiographic (ECG) interpretation is unknown. The purpose of the study was to determine whether intravenous adenosine improved the diagnostic accuracy of difficult to diagnose tachyarrhythmias when used by physicians with different levels of training in ECG interpretation. We studied 28 consecutive patients presenting with wide and narrow complex tachyarrhythmias, in whom adenosine was given specifically for diagnostic purposes. Two groups of physicians, attending (n = 14) and housestaff (n = 10), reviewed each ECG before and after the administration of adenosine. For narrow complex tachyarrhythmias, neither physician group derived diagnostic benefit from the use of adenosine. However, for wide complex tachyarrhythmias, the diagnostic accuracy of the housestaff group significantly improved with the use of adenosine (pre = 54%, post = 70%, p < 0.01), while the attending physician group had no significant improvement (pre = 61%, post = 71%, p = NS). This study suggests that adenosine provides useful diagnostic information to physicians less experienced in ECG interpretation when presented with patients having wide complex tachyarrhythmias of uncertain origin.

Role of adenosine in the diagnosis and treatment of tachyarrhythmias in pediatric patients.

Tachyarrhythmias are common rhythm disturbances in infants and children. Despite the availability of diagnostic criteria arrhythmias are sometimes commonly misdiagnosed. Recent reports suggest that an endogenous purine nucleoside, adenosine, has a diagnostic effect in narrow QRS complex tachycardias, in addition to terminating supraventricular tachycardia involving the atrioventricular node. This report reviews the authors' experience with the use of adenosine for diagnosis of narrow and wide complex tachyarrhythmias in children. Adenosine was administered to 43 patients with several types of tachyarrhythmias (mean age, 8.3 +/- 5.24 years). Nineteen patients had structural or acquired heart disease. Of the 43 patients there were 28 (65%) several different types of narrow QRS complex tachycardia and 14 (33%) ventricular arrhythmias. One patient (2%) had long QT. Adenosine terminated supraventricular tachycardia, in 11 of 12 patients (92%), ventricular tachycardia in five of eight patients (63%), and transiently terminated premature ventricular contractions in two of six patients (33%). The diagnostic ability of adenosine was perfect in eight supraventricular tachycardia. In these eight cases the tachycardia mechanism was unclear before the administration of adenosine, which demonstrated three cases of sinus tachycardia, three of atrial flutter, one of atrial fibrillation and one of atrial fibrilloflutter. Confirmation of the primary diagnosis by adenosine was perfect in five tachyarrhythmias including three cases of atrial flutter, one of atrial fibrillation and one of ectopic atrial tachycardia. The average effective dose of adenosine was 212 micrograms/kg (range, 100-400 micrograms/kg). There were no serious side-effects except transient dyspnea, chest pain and flushing. These findings demonstrate adenosine to be helpful and safe in the diagnosis of tachyarrhythmias.

Case 9-1992

Presentation of CaseA 65-year-old woman was admitted to the hospital for electrophysiologic studies because of ventricular tachycardia.There was a long history of a bipolar affective disorder that was managed with haloperidol and benztropine. The patient was well in other respects until 10 days earlier, when vomiting and diarrhea developed in her and several of her relatives.Four days later the patient entered another hospital because of increasing fatigue, dyspnea, and epigastric pain. On physical examination the blood pressure was 87/54 mm Hg and the heart rate was 220. An electrocardiogram showed a wide-complex tachyarrhythmia with a morphologic pattern . . .