The Concertina Effect in Preexcitation

FIGURE l. Sections clipped from a continuous tracing of lead VI, demonstrating the concertina effect during inhalation of amyl nitrite. As the heart rate increases and cycle length shortens, the QRS complexes progressively narrow (the concertina effect). Concomitantly, the PR interval lengthens while PJ remains constant. Preexcitation disappeared af\er 40 s of inhalation at a heart rate of 111/min, calculated as the reciprocal of the RR interval. An example of the concertina effect is shown in Figure l. The patient was a 33-year-old white man with the WPW syndrome.• Progressive cardiac acceleration was induced by inhalation of amyl nitrite, while a continuous ECG rhythm strip of lead V, was recorded (segments of which are shown in Fig 1). At the initial heart rate of 60/min, there was obvious preexcitation with a classic delta wave and a wide QRS complex of0.11-s duration. As the heart rate increased and cycle length decreased, the QRS complexes moved closer to one another and became progressively narrower. At a heart rate of 111/min, the duration of QRS was only 0.06 s, and no apparent preexcitation remained (also shown by the limb leads). Two other ancillary ECG features are worthy of notation. As the heart rate increased and the degree of preexcitation decreased, there was the expected lengthening of the PR interval, while PJ remained essentially constant. Also, the secondary ST-T wave changes accompanying preexcitation evolved, as anticipated by the concept of the ventricular electrical gradient, namely, the signed algebraic area of ST-T moves opposite to that of QRS, so that the total algebraic area for the entire QT interval remains unchanged. The analogy of the concertina effect is graphically and visually succinct. Therefore, its metaphoric beauty is worthy of preservation in its precise, original form. jowph Grayzel, M.D. Engkwood,New]ersey

REFERENCES 1 Oreto G, Donato A, Carerj S. Pseudo pre-excitation with concertina effect in idioventricular tachycardia. Chest 1991; 99:514-15 2 Ohnell RF. Pre-excitation cardiac abnormality: pathophysiological, patho-anatomical and clinical studies of excitatory spread phenomenon-bearing upon problem ofWPW electrocardiogram and paroxysmal tachycardia. Acta Med Scand [Suppl] 1944; 152:1-167 3 Grayzel J. Electrocardiographic criteria in the difl'erential diagnosis of pre-excitation (WPW syndrome) and arteriosclerotic heart disease. N Engl J Med 19.58; 259:369-74

'lb the Editor: W, thank Dr Grayzel for his thoughtful comments about the metaphoric concept of the concertina effect and for having further clarified the precise mechanism governing the movements of the concertina or accordion. On the basis of the definition reported by Dr Grayzel, it appears to us that our tracing may still be defined as an example of the concertina effect. This is because in our observation the progressive widening of the QRS complexes manifested during prolongation of the cardiac cycle, while the heart rate

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increase resulted in narrowing of the ventricular complexes. In other words, the longer the PP interval, the wider the QRS complex, and vice versa. This conforms to the definition of the concertina effect quoted by Dr Grayzel. Although in our tracing the cardiac cycle length variations are slight, they can still be appreciated (see our Fig 1). A bias inherent in the use of the term "concertina effect" could be the fact that such an effect is associated with preexcitation, a condition that was absent in our case. \\\l should, therefore, have stated that the tracing is an example of pseudo-preexcitation associated with pseudo-concertina effect. Regardless ofthe presence of true concertina effect, our presentation was focused on the fact that idioventricular tachycardia may mimic the WPW syndrome with variable degrees of preexcitation.

Giuaeppe Ofl!to, M.D., Antonino Donato, M.D., F.C.C.P. and Scipione Carerj, M.D.,

Univeraity of Memna, Mesaina, ltal11

Unrecognized Em bolus

Central Venous Catheter

'lb the F..dUor:

Catheter and guide-wire fragment embolization is an infrequent complication of central venous access procedures. The serious morbidity and mortality of approximately 45 percent directly attributable to the foreign body may be due to endocarditis, chamber perforation, dysrhythmias, pulmonary thrombosis, and/or embolism.'.. Complications are minimized by early recognition and prompt removal of the fragment by transvenous techniques. •.s A 69-ye&N>ld man with emphysema and stable angina had a respiratory arrest. During resuscitation, a single-lumen central venous catheter was placed in the right subclavian vein without complication. A triple-lumen catheter was exchanged over a guide wire. However, during removal of the single-lumen catheter, a 20.5cm fragment was accidentally lost into the central circulation. For 17 days the fragment was not recognized on portable chest radiographs. During cardiac catheterization, the fragment was discovered with one end in the right atrium and the other in the hepatic vein. It was retrieved via percutaneous basket catheter. Retrospective viewing of the radiographs showed the fragment (Fig 1). Fragments that do not cause immediate complications and that are not Immediately retrieved cause a significant amount of morbidity and mortality. In three different series, the mortality was 24 percent,• 22 percent,• and 60 percent.' Many series report delays of days to years prior to removal of fragments but do not explain Conmuricatlons to the EdlDr