patients suggeststhat support devicesmay be associated with an increased morbidity and mortality.7 This study demonstratesthat angioplasty of LMCA stenosiscan be performed with a high successrate and suggeststhat angioplasty of unprotected LMCA is a viable option for patients with prohibitive surgical risk. However, the data should be interpreted cautiously, since selection bias and a relatively small number of patients may have contributed to thesefavorable results.Furthermore, closefollow-up is essentialbecausea high restenosis rate may occur in these patients,’ and a significant proportion of these patients require additional revascularization proceduresduring the ensuing years. 1. O’Keefe JH, Hartzler GO, Rutherford BD, McConahay DR, JohnsonWL, Giorgi LV, Ligon RW. Left main coronary angioplasty:early and late resultsof 127 acute and elective procedures.Am J Cardiol 1989;64:144-147.
Symmetry, Broken Symmetry, Pure Ventricular Parasystole
2. Ryan TJ, Faxon DP, Gunnar RM, Kennedy JW, King SB III, Loop FD, PetersonKL, ReevesTJ, Williams DO, Winters WL, Jr, Fisch C, D&an&is RW, Dodge HT, ReevesTJ, WeinbergSL. Guidelinesfor percutaneoustransluminal coronary angioplasty.A report of the American Collegeof Cardiology/American Heart Associationtask force on assessmentof diagnosticand therapeuticcardiovascular procedures(subcommitteeon percutaneoustransluminal coronary angioplasty). Circulation 1988;78:486-502. 3. Stertzer SH, Wallsh E, Bruno MS. Evaluation of transluminal coronary angioplasty in left main coronary artery stenosis (abstr). Am J Cardiol 1981;47:396. 4. Shani J, Gelbfish J, Rivera M, Hollander G, Greengart A, Lichstein E. Percutaneoustransluminal coronary angioplasty:relationship betweenrestenosis and inflation times (abstr). J Ant Coil Cardiol 1987;964A. 5. Kaltenbach M, Beyer J, Walter S, Klepzig H, Shmidt SL. Prolongedapplication of pressurein transluminal coronary angioplasty. C&et Curdiouasc Diagn 1984;10:213-219. 6. DiSciascio G, V&row GW, Lewis SA, Nath A, Cole SK, Edwards VL. Clinica! and angiographic recurrence following PTCA for nonacute total occlusions: comparison of one- versus five-minute inflations. Am Hearr J 1990;120:529-532. 7. Herz I, Fried G, Feld H, Lichstein E, GreengartA, Hollander G, Shani J. High risk PTCA without cardiopulmonarysupport (abstr). Circuhztion 1990;82(suppl III):III-654.
and Restored Symmetry
of Apparent
Agustin Castellanos, MD, Pedro Fernandez, MD, Federicd Moleiro, MD, Albert0 Interian, Jr., MD, and Robert J. Myerburg, MD revious reports dealing with the dynamics of “pure” parasystole using mathematic and electronic (pacing-induced) models, respectively, showedthat a number of predictions emergednaturally from mathematic analysis.1,2Therefore, it appearedof interest to determine whether they would also apply to a seriesof patients with clinical (apparently) “pure” ventricular parasystole who were monitored for relatively long periodsof time. In contrast to previousstudies,Glass et al’ had the ingenious idea of analyzing the number of sinus beats interposed between 2 consecutivemanifest parasytolic beats. They observed that, with the rates being practically constant, a detailed mathematic description could be made using 2 parameters:the ratio of ectopic cycle length to sinus cycle length and the ratio of ventricular refractory period to sinus cycle length. From a correlation of these parameters3 basic rules emerged: ( 1) There are at most 3 different valuesfor the number of sinus beats in between parasystolic beats. (2) Only 1 of thesevaluesis odd. (3) The sum of the 2 lesservaluesis 1 less than the larger value.
P
From the Division of Cardiology, Department of Medicine, University of Miami School of Medicine, P.O. Box 016960, Miami, Florida 33101. This study was supported in part by research grant HL-28 130 from the National Heart, Lung, and Blood Institute, Bethesda, Maryland. Manuscript received January 28, 1991; revised manuscript received March 15,1991, and accepted March 18.
256
THE AMERICAN JOURNAL OF CARDIOLOGY VOLUME 68
We attempted to determine whether symmetry (a term extrapolated from Kaku and Trainer,l’ here meaning that sinus andparasystolic rhythms could be linked by the aforementioned mathematic rules) was present in 10 cases in whom continuous ventricular parasystole had been reprospectively identified. In 9 patients, the diagnosis was made by 24-hour Holter recordings and in I the diagnosis was made by long ( 1 to 3 minutes) rhythm strips obtained at frequent intervals from a coronary care unit monitoring device. Table I lists the pertinent information. In the manwe defined the refractory period ner of Glass et a1,1a234 as the shortest interval betweena sinus-induced QRS complex and a parasystolic beat. We attempted to identify symmetry once the diagnosis of parasystole had been made, when sinus cycle length and ectopic cycle length were first found to be “‘constant” (i.e., with variations of
Symmetry, Broken Symmetry, Pure Ventricular Parasystole
2. Ryan TJ, Faxon DP, Gunnar RM, Kennedy JW, King SB III, Loop FD, PetersonKL, ReevesTJ, Williams DO, Winters WL, Jr, Fisch C, D&an&is RW, Dodge HT, ReevesTJ, WeinbergSL. Guidelinesfor percutaneoustransluminal coronary angioplasty.A report of the American Collegeof Cardiology/American Heart Associationtask force on assessmentof diagnosticand therapeuticcardiovascular procedures(subcommitteeon percutaneoustransluminal coronary angioplasty). Circulation 1988;78:486-502. 3. Stertzer SH, Wallsh E, Bruno MS. Evaluation of transluminal coronary angioplasty in left main coronary artery stenosis (abstr). Am J Cardiol 1981;47:396. 4. Shani J, Gelbfish J, Rivera M, Hollander G, Greengart A, Lichstein E. Percutaneoustransluminal coronary angioplasty:relationship betweenrestenosis and inflation times (abstr). J Ant Coil Cardiol 1987;964A. 5. Kaltenbach M, Beyer J, Walter S, Klepzig H, Shmidt SL. Prolongedapplication of pressurein transluminal coronary angioplasty. C&et Curdiouasc Diagn 1984;10:213-219. 6. DiSciascio G, V&row GW, Lewis SA, Nath A, Cole SK, Edwards VL. Clinica! and angiographic recurrence following PTCA for nonacute total occlusions: comparison of one- versus five-minute inflations. Am Hearr J 1990;120:529-532. 7. Herz I, Fried G, Feld H, Lichstein E, GreengartA, Hollander G, Shani J. High risk PTCA without cardiopulmonarysupport (abstr). Circuhztion 1990;82(suppl III):III-654.
and Restored Symmetry
of Apparent
Agustin Castellanos, MD, Pedro Fernandez, MD, Federicd Moleiro, MD, Albert0 Interian, Jr., MD, and Robert J. Myerburg, MD revious reports dealing with the dynamics of “pure” parasystole using mathematic and electronic (pacing-induced) models, respectively, showedthat a number of predictions emergednaturally from mathematic analysis.1,2Therefore, it appearedof interest to determine whether they would also apply to a seriesof patients with clinical (apparently) “pure” ventricular parasystole who were monitored for relatively long periodsof time. In contrast to previousstudies,Glass et al’ had the ingenious idea of analyzing the number of sinus beats interposed between 2 consecutivemanifest parasytolic beats. They observed that, with the rates being practically constant, a detailed mathematic description could be made using 2 parameters:the ratio of ectopic cycle length to sinus cycle length and the ratio of ventricular refractory period to sinus cycle length. From a correlation of these parameters3 basic rules emerged: ( 1) There are at most 3 different valuesfor the number of sinus beats in between parasystolic beats. (2) Only 1 of thesevaluesis odd. (3) The sum of the 2 lesservaluesis 1 less than the larger value.
P
From the Division of Cardiology, Department of Medicine, University of Miami School of Medicine, P.O. Box 016960, Miami, Florida 33101. This study was supported in part by research grant HL-28 130 from the National Heart, Lung, and Blood Institute, Bethesda, Maryland. Manuscript received January 28, 1991; revised manuscript received March 15,1991, and accepted March 18.
256
THE AMERICAN JOURNAL OF CARDIOLOGY VOLUME 68
We attempted to determine whether symmetry (a term extrapolated from Kaku and Trainer,l’ here meaning that sinus andparasystolic rhythms could be linked by the aforementioned mathematic rules) was present in 10 cases in whom continuous ventricular parasystole had been reprospectively identified. In 9 patients, the diagnosis was made by 24-hour Holter recordings and in I the diagnosis was made by long ( 1 to 3 minutes) rhythm strips obtained at frequent intervals from a coronary care unit monitoring device. Table I lists the pertinent information. In the manwe defined the refractory period ner of Glass et a1,1a234 as the shortest interval betweena sinus-induced QRS complex and a parasystolic beat. We attempted to identify symmetry once the diagnosis of parasystole had been made, when sinus cycle length and ectopic cycle length were first found to be “‘constant” (i.e., with variations of
