Pulse Deficit During Ventricular Tachycardia

To the Editor: Standard orders requiring both apical and radial pulse rate measurements are physiologically sound in patients with atrial fibrillation. The marked variability of cycle length, with attendant changes in diastolic filling and left ventricular stroke output, results in discrepancies between the timed apical beat and peripheral pulse, thereby effecting the “pulse deficit.” We describe here such a pulse deficit in a subject with ventricular tachycardia, a 47-year-old man suffering from coronary artery disease. An unusual feature in this case was the slow and regular cadence of the radial pulse, which resulted in a “peripheral bradycardia.” Figure 1 shows the simultaneously recorded mitral area (MA) and tricuspid area (TA) phonocardiograms, external carotid pulse tracing (CT) and lead 2 (L2) of the patients electrocardiogram. This demonstrates QRS complexes occurring at a rate of 150/minute, compatible with either of the following diagnoses: 1) ventricular tachycardia, or 2) A-V junctional tachycardia with aberrant ventricular conduction. Interestingly, according to the ECG (Fig 1), every third QRS complex resulted in a large deflection on the carotid pulse recording (pulses numbered 1–6). Palpation of the radial pulses revealed a regular rhythm and effective rate of 50/minute. Since the peak pulse amplitudes of the effective pulsations of our subject were almost equal in degree, the peripheral findings were consistent with a bradycardia. Palpation of the apex beat revealed a heart rate of 150/minute. Examination of Figure 1 further indicates that only those QRS complexes preceded by identifiable P waves resulted in appreciable pulses. It can be surmised that the properly timed atrial contribution to left ventricular stroke output1Linden RJ Mitchell JH Relation between left ventricular diastolic pressure and myocardial segment length and observations on the contribution of atrial systole.Circ Res. 1960; 8: 1092Crossref PubMed Scopus (42) Google Scholar was operative in this subject. In addition, synchronization of the effective atrial contractions with those of the ventricles for every third beat resulted in a regular cadence to the pulse. Since ventricular tachycardia usually occurs in association with atrioventricular dissociation, jugular venous2Tavel ME Clinical Phonocardiography and External Pulse Recording. Year Book Medical Publishers, Chicago1967: 192Google Scholar and arterial pulses3Wilson WS Judge RD Siegel JH A simple diagnostic sign in ventricular tachycardia.N Engl J Med. 1964; 270: 446Crossref PubMed Scopus (13) Google Scholar will vary with changing P-R intervals. The findings described in this report are rarely encountered but suggest that apical rates be routinely obtained in all cardiac patients. The technical assistance of Carole Crevier, Jeanette R. Goff, Carol Graves, R.N., Bettie Jo Massey, Nancy Moffatt, R.N., and Sydney Peebles is gratefully acknowledged.