Molecular technique identifies the pathogen responsible for culture negative infective endocarditis

A case of culture negative endocarditis complicated by immune complex glomerulonephritis and severe aortic regurgitation necessitated aortic valve replacement. Empirical treatment with penicillin and gentamicin according to UK guidelines was started. The pathogen, Streptococcus sanguis, was later identified by polymerase chain reaction amplification and sequencing of bacterial 16S ribosomal RNA. This molecular technique is likely to be of increasing importance in determining the aetiology of culture negative infective endocarditis, thus providing essential treatment and epidemiological information.

The role of echocardiography in the diagnosis of aortic dissection

Echocardiography is now an integral part of the assessment of patients before, during and after cardiac surgery. For example, mitral valve repair or myectomy would rarely now be contemplated without echocardiography. Echocardiography is essential for the correct diagnosis of valve disease and to plan the appropriate timing of valve surgery, for the assessment of left ventricular function, for the detection of many postoperative complications, and for the follow up after valve surgery or repair of aortic dissection. Although surgeons are increasingly well trained in echocardiography, a specialist in the technique is still required in order to keep abreast of the dramatic advances in technology and interpretation which have occurred over the past five years and which continue unabated.

Value of physical signs in the diagnosis of ventricular tachycardia

BACKGROUND

Although the use of physical signs for the diagnosis of ventricular tachycardia (VT) was described in the early 1900s, their value in this role has never been systematically assessed.

METHODS AND RESULTS

Using a blinded, randomized protocol, we examined the ability of 26 clinicians to detect ventriculoatrial (VA) dissociation during cardiac pacing in 21 patients with both atrial and ventricular pacing wires in situ after successful ablation of accessory pathways. In protocol 1 (10 patients), pacing was randomized to either ventricular pacing alone (simulating VT) or to atrioventricular sequential pacing (simulating supraventricular tachycardia or VT with intact VA conduction) at rates of 150 or 180 beats per minute. Each patients was examined by four clinicians blinded to the pacing mode. Clinicians were asked to make a diagnosis of "VA association" or "VA dissociation" after examining the patient for variability of the arterial pulse, jugular venous pulse (JVP), and first heart sound. In protocol 2 (11 patients), randomization of pacing mode was performed between examination of each of the three physical signs so that the value of each sign was assessed individually. In protocol 1, a diagnosis of VA dissociation (VT) was made in 21 of 40 observations, with a specificity of 75%, sensitivity of 70%, and a positive predictive value (PPV) of 71%. In protocol 2, from a total of 132 observations (44 for each sign), the sensitivity, specificity, and PPV for a diagnosis of VT were as follows: arterial pulse, 61%, 71%, 70%; JVP, 96%, 75%, 82%; and first heart sound, 58%, 100%, 100%.

CONCLUSIONS

It is concluded that, in patients with a regular tachycardia of uncertain origin, clinically detectable variations in the first heart sound and JVP are highly specific and sensitive indicators, respectively, of a diagnosis of VT. Assessment of the arterial pulse is of little value in this role.